continous dyeing project

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Continous dyeingContinous dyeingContinous dyeingContinous dyeing 1111

PRESTON UNIVERSITY

MILL REPORT

Submitted By:

NAME Registration No

AAMIR SHABBIR 1617-304003

SALMAN MANZOOR 1617-304009

PrefacePrefacePrefacePreface

In line with recent trends toward high-quality production and diversification in the textile

processing , much efforts is being exerted to improve the performance of mixed fabrics of

natural and synthetic fibres and to introduce the new product with new values.

This technical information presents a detailed description of the standard working procedure

adopted under normal practice for continous dyeing of polyester/cellulosic blended fabrics,a

and series of important suggestions over the selection of dye sftuff.

As continous dyeing polyester /cellulosic blended fabrics involves a large variety of fibre

substrates, processing methods and recommendable dye stuffs, in this information two

possible dye stuffs are described—one is disperse vat combination and second is disperse

reactive combination .

AcknowledgmentAcknowledgmentAcknowledgmentAcknowledgment

All thanks are due to Almighty “ALLAH” most beneficial and merciful who enable us to

complete this project.

The completion of this project is perceived as the fruitful result of and incredible effort,

devotion and hardwork. It can be stated without any hesitation that this subject is the

outcome of the joint effort of all concerned by successfully negotiating the various tedious

problems and hurdles.

We are particularly thankful of S.M Qutab ,our project advisor for the guidance and

valuable cooperation render by him at any stage regarding this project. He full indulged

himself to facilitate our job whenever approached him to seek guidance regarding this

study.

Finally we acknowledge a debt of gratitude to our parents and other encouragement, who led

us to complete this project work.

Authors


COTTON

Cotton is a natural fibre. It has cellulose as its major constituent.

COTTON IN PAKISTAN: -

Cotton is cultivating in Pakistan on 40 to 50 lack acres

and gives about 30 to 40 million bales of cotton per year. Since, cotton is cultivated

under different conditions, and its quality various from area to area, field to field,

variety to variety, plant to plant, ball to ball. Butt in industries we want cotton of

uniform quality and also fixing of price depended on quality of cotton.

PROPERTIES OF COTTON

o Cotton consist of pure cellulose (C6H10O5)n

o Cotton fibres have a flat, twisted and ribbon like appearance.

o It absorbs water and does not dry quickly. (SMR = 8.5%)

o It is not damage by alkali

o It is damaged by acids.

o Cotton may be dyed with variety of dyes.

o It is highly flammable fibre.

Cotton crop is ready in July. It is cut and come into ginning mills. In Pakistan, over

1200 ginning factories are working that are producing 10 million bales of cotton.

Standard weight of cotton bale is 170 kg / bale. These bales used in spinning mills to

produce the yarn. Every year almost 137050 ton cotton is consumed bales of raw

cotton are come into spinning unit & after long process this raw cotton is converted

into the yarn.

Large scale spinning mills = 503

Yarn is converted into fabric in weaving mills.

In Pakistan, 16800 organized weaving mills are working


Production of cloth

o Cotton cloth 39402000 square meters

o Blended cloth 4903000 square meters

o Total cloth 44305000 square meters

USES:

Curtain, garments, household things etc

These Greige fabric go to garment industry where after processing it is

converted into garments.

Garment Industry

No of unit over 2500

Sewing machines 305000

END USES OF COTTON

Cotton is also widely used in blends with polyester for an extensive

range of use.


Greige Department

INTRODUCTION:

Greige fabric that buys from different weaving units comes in

this department. In this department inspection of fabric is done. Accepted fabric is

send to next department. There are two inspection systems that are mostly used, one

in 10 point American system and other is 4 points Japanese system is used.

I- Inspection / Grading

II- Lot making

III- Mending

I-Inspection / Grading: -

The main purpose of the inspection is to check the Greige fabric for identify the

faults.

Weaving Faults: -

Double Ends, Loose Ends, Broken Ends, Wrong Dent/Draw,

Loose Selvedge, Double Pick, Miss Pick, Design Cut, Knots,

Hanging Threads, Float,

Mechanical Faults: -

Starting Marks, Rapping Marks, Mending Marks, Hole /Cuts, Oil

Stain

Yarn Faults: -

Cockled Yarn, Weft Slub, Slubby Weft, CEP, Count Variation,

Hair, Jute, P Proplyene, Black Ends.

Others: -

Oily Weft, Sizing Stain, Hard Size.

Minor Faults: -

The faults can be removed easily in further processing such as in

scouring, bleaching and mercerizing etc.


Major Faults: -

Those faults that can not be removed in further processing are major

faults such as starting mark, rapping mark, whole etc.

4 Point Penalty System

PENALTY POINT

1 2 3 4

Defects along the

warp except holes

and torn

Up to 3

3-6

6-9

9-36

Weft defects except

cracks holes and torn

Up to 3

3-6

6-9

9-12

Cutting Faults � Holes and tears ¼ and over

� Cracks / open set marks ¼ and over

Holes or Torn

=

=

=

¼

inches

Points per 100 square yds = Total Penalty Point * 100 *36

Length (Yard) * Width (yards) to supplier Approved Rejected

II-LOT MAKING: -

Lot making is the process which is done before Pretreatment.

Lot making is done for easy handling, transportation and dyeing facilities.

Considerations for the lot making are: -

1. Fibre types

2. Constructions

3. Greige width


4. Greige lot

5. Convenience of processing and transportations.

6. Source

7. Customer needs

This process is done after see the greige fabric from weaving (lots) then applies the

above factors. Normally 2100 meter fabric easily handling. When fabric come from

weaving then one number is write on the fabric by weavers in order to different

looms, different firm yarns etc. but in the dyeing factories. They had done lot making

under 7 factors.

III-MENDING: -

The correction of the mendable class is called mending. It is also called

repairing of faults. Mending is done by physically and chemically.

I-PHYSICALLY MENDING: -

In the physical mending these faults are removed broken

ends, broken picks, knots, contaminations.

Ii-CHEMICALLY MENDING: -

In the chemical mending these faults are removed stains,

oils, waxes, rust, soils, sighting colours.

TYPES OF OIL AND STAINS

Water Soluble Inorganic salts, urea, sugar

Pigments Carbon Black, Silicates, and Metal oxides.

Fats and Oils Animals, Vegetables and minerals

Proteins Blood, milk

Bleachable dyes Fruits, vegetables etc.

STITCHING SECTION

In stitching section we stitch the no of small lots to make a lot of

required.


This is divided into three parts

1. Plate form

2. Unfolding machine

3. Stitching machine

1-PLATE FORM: -

This contain unstitch fabric in the form of rollers, bails, and

pallets.

3-UNF OLDING MACHINE: -

By using this machine fabric is unfold and plaid in

trolleys.

4- Stitching machine: -

Now stitching machine is used to stitch the fabric width wise

and store in trolleys.

INTRODUCTION: -

• Stitch should be straight.

• Selvage of one lot is stitch on the selvedge of other lot.

NOTE: -

The fabric come from grey store, are sent in the bleaching department. The

lot depends upon many rolls of fabric. In a bleaching department theses rolls are

opened, unwind so that the fabric rolls could be stretched with each other for further

process. The selvedge of a fabric of roll is stretched the selvedge of opened roll of

fabric. Now the fabric is kept in trolleys. The numbers of trolleys are different with

each other. A single trolley have unique number 1,2,3,4,5,6,7,-----------315, 316 so on,

so that the fabric lot should be identified by trolley fabric is kept 1500 to 2100 meters

according to the quality of the fabric. We can not keep fabric more then 2100 meter.

After keeping fabric in a trolley a separate job card is allotted to a single trolley.

There are following information mentioned on a job card e.g. date, contract, customer,

ContinoContinoContinoContinous dyeingus dyeingus dyeingus dyeing 9999

constructions, shade, process department, grey Lot #, fabric type, proc Lt #, quality,

fabric source, sub-batch #, sub-batch # Qty, grey width, M/c code, date, shift, start,

End, Meters, trolley No, signature operator and comments.

First of all write starting process Date, 01-08-2005, marketing persons allots separate

Contract No # NDF/OG.3688. There are many lots may be in a single contract,

Customer Name, Mian Textile Ltd etc. Construction, 20.16 / 118.63 etc. Shade,

what is a shade required black, blue, navy blue. Process Departments Bleaching,

Mercerizing. Grey Lt #, the persons of grey store allot separate No# 16067 etc.

SINGING AND DESIZING PROCESS

SINGING: -

When the cloth comes from the loom it has small fibres which are called

fuzz. It must be removed by singing process. Mostly common used

method is gas singing by the help of gas burners.


IMPORTANCE OF SINGING: -

Singing helps us to minimize or reduce the pilling

effect. Pilling give harsh or bed look to fabric. It

must remove from fabric to get good quality

DESIZING: -

Starch remove from the fabric is called desizing. Desizing is reverse of

sizing and is also called steeping. Its main objective is to degrade size

into soluble product so that after washing sizes remove from fabric and

ready for subsequent process.

BRUSH SINGING

The fabrics pass through Electromagnetic and Nomatic rollers, in

Nomatic rollers air pressure and in electromagnetic rollers electricity

these rollers control the width of the fabric the brushing rollers are

moving by motor. Now the fabric pass through six brushing rollers

three are move in clockwise direction and three are move in anti

clockwise direction below brushing portion of machine present Dust

Collector which is collecting the dust . Now the fabric pass through the

Draw Rollers, these rollers are plastic coated the function of this rollers

give grip to the fabric so that the fabric do not slip and full the fabric.

Draw Rollers are also moved by motor. The fabric come on a guide

roller then fabric pass through the Dancer roller, the function of the

dancer roller keep tight the fabric should be come tight next part of

machine


GAS SINGING

In gas singing cloth is passed over gas flames. Now the fabric come in

gas singing portion, there are seven rollers in gas singing portion which

have cold water inner portion so that the fabric do not burn. In this

portion of machine there are four burners which are removing the fuzz,

four gas burners are used and are arranged so that first the face and then

back side of the cloth singed in a single passage, above this machine

Dust collector which is collecting the dust. Four rollers are driven by the

four motors. Flame length can be controlled by proper setting of air

pressure and its width should be adjusted according to the width of the

fabric. Back side of gas singing machine pipes are present yellow pipes

are giving gas to burners and white pipes are giving air to burners.

COMMON FAULTS: -

Uneven singing effect

• Across the width

• Across the length

These effects appear in the form of horizontal and vertical strips. These faults of

singing detect the dyeing and these faults are unremovable.

NOTE: -

A suitable guiding principle for singing is the shouter flame fabric contact.

KYOTO GAS SINGING MACHINE: -

The speed of machine is 120meter/minute.

The total capacity of machine is 82meter fabric. Machine 120000 – 135000 meter

fabric singed and desized in 24 hours.

In continuous process the machine used for singing and desizing.

In this machine singing and desizing is done same time after one another.


MACHINE PARTS AND FUNCTIONS

Enterence

* Electromagnetic rollers

* Nomatic rollers

* Brushing rollers

* Dust collector

* Draw rollers

* Dancer roller

* Gas burners

* Rotary filter

* Saturators

* Expenders

* Padders

* Winding roller

ENTERENCE : -

From trolley the fabric enter in the machine by the help of tension roller.

There are four pair of cloth guider in this section which help to

minimize the crease.

BRUSHING ROLLERS: -

There are six brushing rollers in brushing

portion of machine. Three are move clock wise direction and three are

move anti clock wise direction. The main purpose of these brushing

rollers is to remove fluff from fabric surface. It contains suction pump

that sucks fluff and with the help of showers fluff is removed from

suction pomp.


DUST COLLECTORS: -

There are two dust collectors in machine,

which are collect dust from machine. First dust collector present below

brushing portion of machine and second is present above gas singing

portion of machine.

DRAW ROLLERS:-

These rollers are plastic coated. These rollers

provide grip to the fabric so that fabric do not slip, pull the fabric.

DANCER ROLLERS: -

The function of these rollers keeps tight to the

fabric. There are three dancer rollers are present in machine. 1st dancer

roller is present between brushing and gas singing portion of machine

above draw rollers. 2nd dancer roller is present between two saturator

along above padder. 3rd

is present along above solution tank.

GAS BURNERS: -

There are four gas burner are present in machine. In

these burners gas and air is present. Yellow pipes back side of gas

singing machine are providing gas to the burners and white pipes are

providing air. Regulator distributes the air. With the help of two drawers

and one dancer, the fabric from brushing section enter into singing

section. it contains four burners. Water flow through the burners so that

fabric remain safe from burning. The maximum temperature of the

burner is 750Co and the pressure of the gas is 4.1 – 40-.7 kpa, while air

is 6.1 – 6.9 kpa. Blue flame is touched with surface of the fabric.

Burners are controlled by control panel. The flame touch with fabric at


45 angle. It can be change according to the quality of the fabric. Flame

size normally use is 5” for Lycra quality both lower burner are not used.

ROTARY FILTER: -

Rotary filter is present along with first saturator.

Saturators are connected with each other by pipes for solution way.

Rotary filter take solution from saturator and filter it, dirty solution is

drained and clean solution is supplied to the saturator. Small motor

revolve the rotary filter.

SAURATORS: -

There are two saturators are present in machine.

Saturator has seven guide rollers are up an eight are down. Saturator

solution capacity 1250 liter, temperature of saturator 75Co fabric

capacity of saturator is 17 – 20 meters, desizing is done with the help of

the enzyme desizing which is applicable at 7 PH.

EXPENDERS: -

There are three expenders are present in machine. The

shape of expender is like banana. The function of expender, expend the

width of the fabric. 1st expender is present between two saturator and 2

nd

is present after second saturator and 3rd

is present along winding roller.

PADDERS: -

The functions of Padders squeeze the extra desizing

solution from fabric. There are two Padders in machine. 1st is present

between two saturator. 2nd

saturator is present after second saturator.

The weight is 1 ton.

WINDING ROLLER: -

Winding roller is present in the last of machine.

This is winding the fabric on batcher. The quantity of the fabric on one


batcher according to the quality of the fabric. Winder is a main roller in

winding zone. After completing or rotating time fabric is ready for

bleaching.

DESIZING

It is a process in which we remove starch from the fabric in order to get good

dyeing results. Following types of desizing are carried out,

Rot steeping

Acid steeping

Enzyme desizing

Commonly used desizing is enzymatic /bio desizing.

History of enzymes

The history of modern enzyme technology really began in 1874 when the Danish chemist

Christian Hansen produced the first specimen of rennet by extracting dried calves' stomachs

with saline solution. Apparently this was the first enzyme preparation of relatively high

purity used for industrial purposes.

This significant event had been preceded by a lengthy evolution. Enzymes have been used by

man throughout the ages, either in the form of vegetables rich in enzymes, or in the form of

microorganisms used for a variety of purposes, for instance in brewing processes, in baking,

and in the production of alcohol. It is generally known that enzymes were already used in the

production of cheese since old times.

Even though the action of enzymes has been recognised and enzymes have been used

throughout history, it was quite recently that their importance were realised. Enzymatic

processes, particularly fermentation, were the focus of numerous studies in the 19th century

and many valuable discoveries in this field were made. A particularly important experiment

was the isolation of the enzyme complex from malt by Payen and Persoz in 1833. This

extract, like malt itself, converts gelatinised starch into sugars, primarily into maltose, and

was termed 'diastase'.

Development progressed during the following decades, particularly in the field of

fermentation where the achievements by Schwann, Liebig, Pasteur and Kuhne were of the


greatest importance. The dispute between Liebig and Pasteur concerning the fermentation

process caused much heated debate. Liebig claimed that fermentation resulted from chemical

process and that yeast was a nonviable substance continuously in the process of breaking

down. Pasteur, on the other hand, argued that fermentation did not occur unless viable

organisms were present.

The dispute was finally settled in 1897, after the death of both adversaries, when the Buchner

brothers demonstrated that cell free yeast extract could convert glucose into ethanol and

carbon dioxide just like viable yeast cells. In other words, the conversion was not ascribable

to yeast cells as such, but to their nonviable enzymes.

In 1876, William Kuhne proposed that the name 'enzyme' be used as the new term to denote

phenomena previously known as 'unorganised ferments', that is, ferments isolated from the

viable organisms in which they were formed. The word itself means 'in yeast' and is derived

from the Greek 'en' meaning 'in', and 'zyme' meaning 'yeast' or 'leaven'.

Early developments in Japan

During the early part of this century, enzyme technology was also developing slowly but

surely outside Europe. In the Far East, an age-old tradition prevailed where mould fungi, the

so-called koji, were (and still are) used in the production of certain foodstuffs and flavour

additives based on soya protein (shoyu, miso, tempeh) and fermented beverages (sake,

alcohol). Koji is prepared from steamed rice into which a mixture of mould fungi is

inoculated, the composition of the mixture being passed down from generation to generation.

This formed the basis which the Japanese scientist Takamine developed a fermentation

process for the industrial production of fungal amylase; the process included the culture of

Aspergillus oryzae on moist rice or wheat bran. The product was called 'Takadiastase' and it

is still used as a digestive aid. The method of fermentation suggested by Takamine, the

'surface culture' or 'semisolid culture’ is still actively used in the production of various

enzymes.

Textile Desizing

At about the same time as Takamine was developing his novel fermentation technique,

another field was being opened up for the use of enzymes - the desizing of textiles.

Previously, textiles were treated with acid, alkali or oxidising agents, or soaked in water for

several days so that naturally occurring microorganisms could break down the starch.

However, both of these methods were difficult to control and sometimes damaged or

discoloured the material. It represented great progress, therefore, when crude enzyme extracts

in the form of malt extract, or later, in the form of pancreas extract, were first used to carry

out desizing.

Bacterial amylase derived from Bacillus subtilis was used for desizing, the first time by

Boidin and Effront as early as 1917.


Leather Bating

Investigations carried out by the German chemist and industrial magnate Otto Rohm before

World War I were of great importance for the further development of the industrial use of

enzymes. Among other things, he studied the so called 'bating' process, a step in the

preparation of hides and skins prior to tanning.

According to tradition, bating required the excrement of dogs and pigeons, a fact that did not

improve the image of tanning which was considered a stinking and unpleasant activity.

Rohm's theory was that these excrements exerted their effect because they contained residual

amounts of the animals' digestive enzymes. If this was so, it might be possible to use extracts

of the pancreas directly for bating. Such extracts were tried and produced the expected

positive results. Naturally, Rohm accepted this as confirmation of the correctness of his

theory, but later experiments showed that it was not the animals' enzymes that were active,

but rather enzymes of bacteria growing in the intestinal tract.

The first detergent enzyme

Parallel to his studies of the problems involved in tanning, Rohm investigated other processes

where enzymes would prove even more valuable. Nevertheless, his efforts were not to score

a success until 50 years later. Rohm actually developed the first method for washing protein

stained cloth in detergents containing enzymes and manufactured the first detergent

preparation containing enzymes.

The enzyme preparation used was pancreatin (extracted from pancreatic glands), which

contains the protein degrading enzyme trypsin.

Breakthrough in detergents was made in 1959, when a Swiss chemist Dr. Jaag, developed a

new product called Bio 40 containing a bacterial protease instead of trypsin.

Sugars from starch

A very important field in which enzymes have proved to be of great value over the last 15-20

years is the starch industry. In 1950s, fungal amylase was used in the manufacture of specific

types of syrup, i.e., those containing a range of sugars, which could not be produced by

conventional acid hydrolysis. The real turning point was reached early in the 1960s when an

enzyme glucoamylase, was launched for the first time, which could completely break down

starch into glucose. Within a few years, almost all glucose production was reorganised and

enzyme hydrolysis was used instead of acid hydrolysis because of the more benefits such as

greater yield, higher degree of purity and easier crystallisation.

The process was further improved by the introduction of a new technique used for the

enzymatic pre-treatment (liquefaction) of starch by using a heat-stable alpha amylase.

Years of research in biochemistry and biotechnology have boosted knowledge of enzymes

for industries as well as research. Many new techniques have been established to modify


enzymes or increase their yields. New techniques for purification of enzymes are constantly

developing and so are being discovered new application of enzymes in medicine, research

and industries

How are Enzymes made?

The starting point for enzyme production is a vial of a selected strain of microorganisms.

They will be nurtured and fed until they multiply many thousand times. Then the desired

end-product is recovered from the fermentation broth and sold as a standardised product.

A single bacteria or fungus is able to produce only a very small portion of the enzyme, but

billions microorganisms, however, can produce large amounts of enzyme. The process of

multiplying microorganisms by millions is called fermentation. Fermentation to produce

industrial enzymes starts with a vial of dried or frozen microorganisms called a production

strain.

One very important aspect of fermentation is sterilisation. In order to cultivate a particular

production strain, it is first necessary to eliminate all the native microorganisms present in

the raw materials and equipment. If proper sterilisation is not done, other wild organisms will

quickly outnumber the production strain and no production will occur.

The production strain is first cultivated in a small flask containing nutrients. The flask is

placed in an incubator, which provides the optimal temperature for the microorganism cells

to germinate. Once the flask is ready, the cells are transferred to a seed fermenter, which is a

large tank containing previously sterilised raw materials and water known as the medium.

Seed fermentation allows the cells to reproduce and adapt to the environment and nutrients

that will be encountered later on.

After the seed fermentation, the cells are transferred to a larger tank, the main fermenter,

where fermentation time, temperature, pH and air are controlled to optimise growth. When

this fermentation is complete, the mixture of cells, nutrients and enzymes, called the broth, is

ready for filtration and purification.

Filtration and purification termed as downstream processing is done after enzyme

fermentation. The enzymes are extracted from the fermentation broth by various chemical

treatments to ensure efficient extraction, followed by removal of the broth using either

centrifugation or filtration. Followed by a series of other filtration processes, the enzymes are

finally separated from the water using an evaporation process.

After this the enzymes are formulated and standardised in form of powder, liquid or granules.


There are two saturators from which desized the fabric. Now the fabric

comes in 1st saturator there are seven guide rollers are up and there are

eight guide rollers are below. First saturator have three, motors 2nd

4th

6th

rollers are driven by three motors, at the top of 1st saturator

exhauster present which exhaust the heat. After this the fabric passes

through the Padder which are squeeze the extra desizing solution from

fabric then fabric pass through the Dancer roller. Now fabric comes in

2nd

saturator, 2nd

saturator similar to first saturator. These saturators are

connected by pipe. Desizing is done with the help of the Enzyme

Desizing which is application at 7 PH

Advantage of singing come desizing

• Short process

• Cheap process

• High production

• Less labor cost

• More impurities are removed

PREPARATION OF DESIZING SOLUTION

a. First of all wash the tank

b. The tank fills by 400 liter water and then staring

c. First of all salt is added as a (catalyst) then S.E is

added then K.D (detergent) is added and then L100

(desizer) is added

d. Tank fills by 1000 liter water. Measure 1000 liter

water by rod.

e. Start the chemical feed pump and open flow meter

according to the using of chemical.

f. Make a record how much is using.


RECIPE: -

For heavy quality of cotton

L100 (Enzyme desizer) 14gm/l

KD (Detergent) =

6gm/l

SE (sequesting agent) = 4gm/l

NaCl = 5gm/l

For heavy quality of cotton

L100 (Enzyme desizer) 10gm/l

KD (Detergent) =

5gm/l

SE (sequesting agent) = 4gm/l

NaCl = 5gm/l

Note: After desizing the fabric batcher is kept for 6-8 hours in rotation to keep the desizer

within the fabric. It is so because bacterias produced by enzymes take some time to eat

starch. If we will keep it for longer time than a limit then bacterias will start eating fabric

after finishing the starch, and if it will keep for a shorter time then starch could not be eat

completely by the baterias. The PH is maintained from 7-8 and the RPM is usually keep 100.


SCOURING

Scouring is a process of removing natural as well as synthetic impurities. In this

process maximum cleaning c effect is produced with minimum effect on cellulose

natural fibres contains oils, fats, waxes, minerals, leafy matters and notes as impurities

that interfere with dyeing and finishing. Synthetic fibres contain producer “spin

finishes” coning oils and knitting oils. Mill grease uses to lubricate processing

equipment shift on the processing fabric and contaminate it. “The process of

removing these impurities is called scouring” even through these impurities are not

soluble in water and can be removed by extraction, dissolving.

The impurities in inorganic solvent, emulsification, forming stable suspension of the

impurities in water and sponification converting contaminates into water soluble

compounds.

CHEMISTRY OF OILS, FATS AND WAXES

Many of contaminates removed in scouring both natural and man made are fats, oils

or waxes. Many useful products, some used in scouring are derived from them.

FATS: -

Chemistry fats and waxes are esters of fatty acids: fats also known as

triglyceride, are abundantly produces by natural s vegetable oils (corn, olive, coconut,

linseed and soy bean oil) and as fatty deposit in animal ( mutton, pork and fish

another source of waxes is vegetable matter, predominantly the hard shing outer

coated tropic leaves.

TRIGLYCERIDE: -

Regardless of weather it is of vegetable or animal origins, a fat can

be either liquid or semi solid. A major factor in determining the physical nature of the

fat in the make up of fatty acid compounds.


FATTY ACIDS: -

Fatty acids are long chain alkyl – carboxylic acid. The alkyl radical

can be either completely saturated (saturated fatty acid) or (UN saturated fatty acid)

most common chain length in nature is C18.

1-Scouring section of L-Box: -

In the opening of the machine the fabric

passes through two Draw rollers are plastic coated. They grip the fabric

otherwise pull the fabric now fabric passes through the dancer roller, dancer

roller keep tight the fabric. Then fabric pass through the Nomatic rollers, there

are four Nomatic rollers opening of the machine. These rollers control the

width of fabric. These rollers have air pressure. Now fabric comes in washing

portion of machine, there are six washers opening of the machine. The

remaining desizing chemical present on the fabric, that is removed in washers.

The temperature of water in washers depends upon the quality of the fabric.

Mostly the temperature of water in fist washer is kept 92Co and the

temperature of other washer are kept 95Co. the temperature of water in fist

washer is kept 92Co so that do not become creases or shrinkage. A single

washer has 21 guide rollers. There are 10 guide rollers are above and 11 are

below. Five motors are present on a single washer, which are revolving the

guide rollers. Heat exchange filter take water from washers and drain. Heat

exchange pump take this cool water and gives to heat exchanger. Heat

exchanger warms the water at 60 and gives to washers. Sensors valve sense

the temperature of water in washers if temperature of water is not according to

the requirement then auto valve automatically opened after automatically are

closed. Steam pipes along with the washers. Booster pump is also connected

with heat exchanger, it gives fresh water to heat exchanger so that the pressure


of water in heat exchanger maintain. Now the fabric comes in scouring

saturators. There are two saturators, in which scouring solution is present.

PREPARATION OF SCOURING SOLUTION

• 400 liter water takes in a tank and stirring it.

• Soda ash added in water

• KEB dissolved in water

• After dissolving there are mentioned thinks, stop stirring.

• Now added caustic and measured by scale.

• Further take water in a tank and tank fill by 1000 liter water.

• The concentration of caustic soda checked according to gm/liter.

• Start the chemical feed pump.

• Flow meter opened according to the uses of chemical.

• Checking the concentration of caustic from saturator after 5 or 10 minutes.

• Make a record of uses chemical and how much concentration of caustic in

saturator.

CHECKING CONCENTRATION OF CAUSTIC FROM SATURATORS

First of all we take scouring solution from saturators. 100 ml water takes in a beaker

and then two or three drops of indicators added. Now we added 1 ml scouring solution

by pipette in this beaker and we will start to added 0.1 concentration of HCl by

burette. We will be added the drops of HCl, at that point the colour of beaker solution

will be changed. It will be noted.

NOTE: -

The concentration of caustic is kept in saturator according to the quality of the

fabric. If concentration of caustic is increased according to the quality of the


fabric then flow meter is decreased. If concentration of caustic is lower

according to the quality of the fabric then flow meter is decreased.

Recipe codes

Chemicals

S1

S2

S3

S4

NaOH 55gm/l 45gm/l 35gm/l 20gm/l

KD 8gm/l 8gm/l 5gm/l 5gm/l

Soda ash 5gm/l 5gm/l 3gm/l 3gm/l

KEB 2gm/l 2gm/l 2gm/l 2gm/l


The length of the machine is 120m

Draw roller

Dancer roller

Stray

Nomatic roller

Padders

Washers

Heat exchanger

Exhaust

Scouring and Bleaching saturator

Steamers

Heat exchange filter

Heat exchange pump

Booster pump

Air compressors

Liquid feed pump

Feeding pump

Dryer


DRAW ROLLER: -

Draw rollers are plastic coated. The functions of these rollers are

grip the fabric and pull out the fabric.

DANCER ROLLER: -

The functions of dancer rollers are keep tight the fabric.

SCRAY: -

The function of scray is when small quantity of fabric remains on the

batcher, we are used stray so that the edge of fabric on batcher do not mistake. The

fabric is felled on the stray slowly – slowly so that the edge of batcher fabric could be

caught.

NOMATIC ROLLER: -

Nomatic rollers have air pressure. The function of Nomatic

rollers are control the width of fabric. There are four Nomatic rollers at the opening of

the L-Box.

PADDERS: -

The function of Padders are squeeze he extra solution from the fabric

WASHERS: -

When fabric come from desizing machine, at that time it has enough

quantity of desizing solution it is removed in washers. There are six washers at the

opening of the machine. There are 21 rollers in a washer. There are 10 are above and

11 are below 2,4,6,8,10 rollers are driven by motors. There are 378 (Three Hundred

Seventy Eight) rollers in 18 washers. The temperatures of washers are kept according

to the quality of the fabric. The washers are connected with each other with pipes.


HEAT EXCHANGER: -

The function of heat exchanger, re-warm the water. The heat

exchanger pump takes cool water and supply to the heat exchanger. The heat

exchanger after taking cool water and after re-warm gives to the washers by pipe.

Heat exchanger warms water temperature 60Co. second heat exchanger present after

first steamer. This heat exchanger is also supply warm water to others 12 washers.

EXHAUSTS: -

The function of exhaust is exhausts the heat. There are 10 exhausts

present in L-Box.

SCOURING AND BLEACHING SATURATORS: -

There are two scouring

saturators. In these saturators fabric is treated with scouring solution. Liquid feed

pump supply scouring solution to the saturators from solution tank by piping. After

five or ten minutes, we check concentration of caustic. Bleaching saturators presents

after 7, 8, 9, 10, 11, 12 washers. There are also two saturators. In which fabric is also

treated with bleaching solution. In these saturators we are also check the

concentration of caustic and H2O2.

STEAMERS: -

First steamer in L-Box has 64 rollers. At upper portion of steamer 13

Plaiter rollers. The running of fabric among these rollers in Zigzag form, fabric

comes on conveyer. The conveyer is perforated from bottom, at the top of conveyer

gaseous phase the temperature of these gaseous is 102Co. Liquid Phase, water

temperature is 100 Co. Water change into steam and convey to the fabric. After

conveyer tension rod is present which give tension to the fabric, the function of

expender in steamer spread the fabric, control the width of fabric. The shapes of


steamer expender like a spring. Now fabric comes in Mini Washing, present Padders,

expender and steel rollers. We supply the hot and cold water to Mini Washing.

Second steamer in L-Box has 17 rollers, other function similar to first steamer. If the

speed of machine is running 90 meter/minute then fabric present in fist steamer and

second steamer.

90 meter/minute * 50 steamer time = 4500 meter

Fabric in First Steamer 4500 meter

90 meter/minute * 30 steamer time = 2700 meter

Fabric in First Steamer 2700 meter

HEAT EXCHANGE FILTER: -

Heat exchange filter is taking fluff water from

washers. It is connected by motor. It is separate the fluff from water and through

water below, from this place heat exchanger pump take water and supply to heat

exchanger.

HEAT EXCHANGER PUMP: -

The function of heat exchanger pump takes cool water

and supply to heat exchanger.

BOOSTER PUMP: -

The function of Booster pump supplies fresh water to heat

exchanger so that the pressure of water maintain in heat exchanger.


AIR COMPRESSOR: -

The functions of air compressor maintain temperature in

panel so that the working of panel do not disturb. For example: -

Inner panel temperature 28.7Co

Outer panel temperature 45.5Co

LIQUID FEED PUMP: -

Liquid feed pump supply scouring solution to the saturators

from solution tanks by piping.

FEEDING PUMP: -

Mostly after maintenance of machine, a lot of solution is required

in saturators in a single passage. Therefore for supply of solution from solution tank

we use feeding pump it is also called a direct feeding.

DRYERS: -

There are 48 (Forty Eight) dryers are present at the end of the machine.

These dryers arrange in 4 columns. Each column contains 8 dryers and a tension

roller lie b/w two consecutive column to maintain the tension. After passing through

44 hot dryers then fabric pass through 4 cool dryers. In last four dryers cool water is

present so that temperature maintains pressure in dryers 0.35 MPa.

TYPES OF ROLLERS

FEED ROLLERS: -

Feed rollers used to control the speed of cloth in the machine.


DANCER: -

It is use to maintain the tension in fabric. It is also adjust according to the

quality of the fabric.

SEQUEEZ ROLLERS: -

It is use to maintain the pickup of fabric. The pickup also

adjusts according to the quality of the fabric.

SPREAD ROLLERS: -

It prevent the fabric from creasing


MERCERIZING

OBJECTIVES

� To increase luster.

� To increase the affinity for dyes.

� To increase the tensile strength.

� To give dimensional stability

� Use of dye after mercerizing is less

� Width control

After mercerizing increase cost of fabric Rs 2.70 per meter

In this process cotton is dipped in a solution of NaOH so that NaOH penetrated in to

the fibre and then NaOH is washed out completely by neutralizing by dilute acid like

sulphuric acid. When mercerizing fibre are examined under microscope. It is seen that

each fibres in twisted ribbon like form. After mercerizing fibres become cylindrical

and free from twists.

To increase the luster cotton must be prevented from shrinkage. This can be achieved

by stretching the yarn or fabric. Shrinkage of the fabric can also controlled by

mercerization.

INSTRUCTION FOR CHILLER OPERATOR

1-How much Be are required according to this Be prepared but for 28 Be, 26 Be or 20

Be prepared according to program.

2-In order to grey fabric 12, 18, 15 caustic Be prepared according to program]


PREPARATION OF CAUSTIC

1- For preparation of 26 Be caustic, take 1200, 1200 liters 32 Be caustic in both

tanks.

2- For preparation of 26 Be caustic in PIT, open the caustic valve and along with

the water valve. When 26 Be should be prepared, circulation of caustic start so

that caustic should be cool.

3- For preparation of 26 Be caustic, take 35 Be caustic and for preparation of 35

Be caustic, 300 liters 48 Be caustic take in to 32 Be caustic.

4- CHANGE OF Be : - when Be of caustic is changed, for change 20 Be from 26

Be, take 48 Be caustic and down the PIT and open the supply of water.

Similarly 26 Be caustic should be prepared.

5- For preparation of 2o Be caustic, down the PIT and open the supply of water.

Similarly 26 Be caustic should be prepared.

6- When operate the machine, clean the filters at caustic supply.

7- After each half hour note the Be of saturators, Titration and Temperature.

8- During operation check the there is no problem in compressor and condenser

and which is coming water from cooling tower, it is cool.

CHECKING Be:-

Take water into TIP from PIT and keep Be meter into TIP. Now

reading noted.

9- Temperature of chiller should be 25Co.

10- After every week wash out the Heat Exchanger.


METHOD OF CHILLER OPERATING

1- First of all operate the cooling tower

2- After this operate the brine pump

3- After this operate the compressor during this check the all valve of operation.

WORKING OF MACHINE

There are two saturators of mercerizing machine. The solution capacity of each

saturator is 700 liter. The solution comes from TIP. When solution above a limit again

come into TIP. NaOH pump take solution from TIP and supply to the heat exchanger.

Brine pump take water from chiller and supply to the Heat Exchanger, from heat

exchange again solution come in to saturators by piping.

When we required change the Be, take solution from TIP and give to third tank and

again solution is prepared. When solution come from saturators Rotary Filters clean

the solution. Fluff is drained and solution comes in to TIP. Similarly this circulation

continues. After passing fabric from 2nd

saturator come on stenter, at the beginning of

the stenter Selvedge Guider, which are maintain the width of the fabric. Scale is

present on chain, on this scale mentioned the width of the fabric according to the

chain. There are Seven Shower Pump, these shower pump are supplying solution to

the fabric. There are Seven Suction Pump, these pump suck the solution. Stenter

wheel are revolving the chain. These are driven by motor. After this 11 (Eleven)

washers are present. The temperature of washers is 95Co after these 48 Dryers are

present. Last four dryers have cool water so that the temperature maintain.


NOTE: -

The capacity of machine is 480 meter fabric

TYPES OF MACHINARY:

There are two types of mercerizing machines.

1-Chain type mercerizing machine

2-Chain less type mercerizing machine.

Chain type KOTO JAPAN MACHINE parts and their function are following


Enterence

Saturators

NaOH Pump

Be control valve

Brine Pump

Brine control valve

Recovery pumps

Rotary Filter

Chain Wheel

Selvedge Guider

Shower Pumps

Suction Pumps

Washers

Dryers

Heat Exchanger


ENTERENCE: -

After bleaching of the fabric is ready for mercerizing. Enterence section

contains guider tension rollers and spreaders. Fabric passes all these

rollers so that fabric contains no crease. Fabric passes through 4

selvedge rollers so that stretch the fabric in order to remove selvedge

crease. This zone also has a scray. It is also very important part of

Enterence. It is used when there is need to change batch of fabric. When

fabric of J- Scray runs the tension of cloth guider is increase because

there is more chance of crease.

1- SATURATORS: -

There are two saturators. The capacity of solution of each

saturator

is 700 liter. it contains caustic solution of required bombe. It

contains three

squeezing rollers and 2 spreaders and 8 Padders.

2- NaOH PUMP: -

NaOH Pump is taking solution from TIP and supply to the Heat

Exchanger, give solution by piping to the saturators.

3- BE CONTROL VALVE: -

How much quantity of Be is required? It is taken in a TIP

from mixers by operating Be control valve. It is being

operated from panel


4- BRINE PUMP: -

The function of brine pump is circulation of water. Brine pump

supply water to the heat exchanger.

5- BRINE CONTROL VALVE: -

Brine control valve control the quantity of water. The

working of Brine control valve is automatically. It is

being operated from panel.

6- RECOVERY PUMPS: -

When we changed the Be of TIP, we take solution from

TIP by first recovery pump and through into third tank.

The second recovery pump is present below showers. This

pump takes solution and give to the Recovery Pump.

7- ROTARY FILTER: -

Rotary filter, filter the dirty water. It drains the fluff and again

supplies water to the washers.

8- CHAIN WHEELS: -

These wheels give direction to the revolving chain. The length of

the chain section is 30 meter and total chain on one side is 60

meters the chain having no of clips. At the start of clips of chain

there is a circular plate that is also moving with the speed of

chain or clips. The function of the circular plate is to open and

closed the clips; in start we keep the width of the chain according

to the width f the fabric. When fabric run some meter width of

the chain is set to the required width of the fabric. Open the chain


width wise very slowly because there is a large chance of fabric tear. After some

distance chain contains 7 showers that shower caustic solution almost 8 bombe on

fabric. This is come from 1st and 2nd washer of mercerizing machine. The purpose of

these showers of caustic is to make sure the well penetration of caustic solution in

fabric.

9- SELVEDGE GUIDER: -

Selvedge Guider, control the selvedge of the fabric.

11- SHOWER PUMPS: -

There are seven Shower Pumps are present. The function of

shower pumps supply solution to the fabric.

12- SUCTION PUMPS: -

There are seven suction pumps. The functions of suction pumps

are sucking the solution.

13- WASHERS: -

There are 11 (Eleven) suction pumps are present. There is

difference between first 3 and remaining 8. There difference is

their construction is change and their capacity of water is

changed. First 3 having 5 rollers up and 6 down and other washer

having 10 up and 11 down. The capacity of water in first three

washers 1000 liter and other washer having capacity of water

1500 liter. The temperatures of all washers are 90Co for cotton

and for cotton Lycra quality is 95Co. 25 meter fabric in single

washer.


14-DRYERS: -

. There are 48 (Forty Eight) dryers are present at the end of the

machine. The function of dryer is dry the fabric. These dryers

arrange in 4 columns. Each column contains 8 dryers and a

tension roller lie b/w two consecutive column to maintain the

tension. After passing through 44 hot dryers then fabric pass

through 4 cool dryers. In last four dryers cool water is present so

that temperature maintains pressure in dryers. The dryer

pressures are 0.35MPa.

15- HEAT EXCHANGER: -

The function of Heat Exchanger, exchange the heat of the NaOH.

IDENTIFICATION OF MERCERIZED COTTON

Mercerized cotton can be identified by its microscopic view. Cotton fabric naturally

flat and twisted (ribbon like) after mercerizing fibre swell, untwist and their cross

section change in to round form.

CONDITIONS

• Cotton should be free from sizes and other impurities. If these are present then

mercerized solution should not well penetrate completely in fabric.

• Temperature required for caustic solution is 25 – 30 Co.

• NaOH is used for this purpose because it is cheap. KOH is also used but it is

expensive.


PRECAUTIONS

• Concentration of NaOH

• Machine temperature

• Extraction of alkali

• Steaming time

• Time

• Proper cleaning of machine

• Same lot of fabric should run at same speed.

• Concentration of alkali should be same for al lot of fabric.

FAULTS

1. If a thread remain in a clip then clip disable to grip properly.

2. If alkali remain in fabric for long time then fabric will weak also white

sport appear on fabric

NOTE: -

If want to cure fabric before dyeing then we do mercerizing after curing

because if we do mercerizing before curing then due to presence of alkali give

yellowness to fabric.


NaOH Be G / L

Be G / L

6.7 48.9

12 86.7

18.8 157.9

19.8 169

20.9 181

22 194

23 206

24 219

25 231.8

26 244.9

26.9 258

27.9 271

28.8 285.2

29.7 299

30.6 312

38 450

50 772


History of Continous Dyeing This invention relates to the dyeing of textile fabrics, and in particular to a continuous

process for dyeing textile fabrics formed at least partially of polyester fibers.

It is known from the technical literature (for example, W. Bernard Praxis des Bleichens und

Faerbens von Textilien [Bleaching and Dyeing Practice of Textiles], Springer Verlag, 1966)

and from pertinent publications that textile fabrics of polyester fibers and/or their blends with

cellulosic fibers can be continuously dyed by the so-called "Thermosol Process." In applying

this method, the fabric is impregnated with a cold to warm, aqueous dispersion of suitable

dyestuffs and auxiliary agents to a defined weight increase, dried, subsequently "thermally

fixed" at temperatures of 180.degree. to 220.degree. C., and again liberated from excessive

dyestuff by washing. During the thermal fixation, the dyestuffs diffuse into the polyester

fiber in a finely dispersed or monomolecular form, and are dissolved in the fiber. The

advantage of this method is the possibility of simultaneously fixing the polyester fibers and

obtaining very fast colors within a short period of time ranging from 40 to 120 seconds at

180.degree. to 220.degree. C.

A prerequisite for the success of the process is that the dyestuffs are already uniformly

distributed in the textile product after the impregnation and intermediate drying. If not,

nonuniform coloration will result. Another prerequisite is that the product is dried before the

thermal fixation, since otherwise the temperatures for the Thermosol Process will not be

reached because of evaporation of the dyebaths.

However, the Thermosol method has been found disadvantageous in practice, in that not all

textile fabrics of polyester fibers can be dyed by this process, and that it is absolutely

necessary to dry the product following the padding. In particular, it is not possible to dye pile

fabrics by this method, since the dyebath migrates to the pile tips and bases during the

intermediate drying, and thus, the product is dyed unevenly. Furthermore, the process is

uneconomical, since the fabric needs to be dried twice during the dyeing process. Even

though attempts have been made to overcome these disadvantages by the use of so-called

migration inhibitors and special padding assistants, they have been unsuccessful in the case

of the pile fabrics, such as, plushes, velvets and velours. A further problem with the pile

fabrics, due to their high bulk and insulating characteristics, is that it is not possible to

achieve Thermosol temperatures throughout the fabric in a reasonably short duration without

overheating and fusing the tips of the pile yarns or leaving inner portions of the fabric

insufficiently heated.

It is, therefore, an object of the present invention to develop a method for continuously

dyeing polyester fibers and filaments and/or their blends with cellulosic fibers, which

overcomes the aforementioned disadvantages and by which also pile fabrics can be

satisfactorily dyed.


SUMMARY OF THE INVENTION

Surprisingly, it has now been found that it is possible to continuously dye textile fabrics of

polyester fibers and filaments and/or their blends without having the aforementioned

disadvantages, when the fabrics are impregnated in an aqueous dyebath, containing

(a) 0 to 5.0 g/l of a thickener;

(b) commercially available disperse dyestuffs in an amount sufficient to dye the fibers to the

desired depth of color;

(c) 2 to 100 g/l of a partially sulfated adduct of ethylene oxide with an alkyl phenol or

C.sub.8 to C.sub.16 fatty alcohols, preferably nonylphenol or C.sub.12 fatty alcohol with 1 to

6 mols ethylene oxide;

(d) 0 to 60 g/l of nonionic or anionic surfactants; and

(e) 5 to 50 g/l of at least one organic compound selected from the group consisting of

aromatic nitrile ethers and ethoxylated chlorophenols.

The fabric is impregnated by any suitable method, such as by padding, up to a weight

increase of 60 to 250%, preferably, 80 to 160%, and is subsequently heated to a temperature

and for a time sufficient to fix the dyestuffs. For example, the fabric may be steamed in the

wet condition for 1 to 20 minutes in a saturated vapor atmosphere of 96.degree.-105.degree.

C., preferably 98.degree.-102.degree. C., then continuously washed at 20.degree. to

60.degree. C. in one to six baths, mechanically drained to a residual moisture of 50 to 90%,

and finally dried for 1 to 10 minutes, preferably 2 to 6 minutes, at temperatures of

140.degree.-210.degree. C., preferably, 170.degree. to 200.degree. C.

DETAILED DESCRIPTION OF THE INVENTION

The method of the present invention is characterized in that it is applicable to all fabric

constructions, and that intermediate drying is not needed. Based on the special composition

of the dyebath, it has thus been made possible to dye polyester fibers, which could not be

dyed by steaming in a continuous process under the aforesaid conditions. Such a method has

been so far unknown, and is both a considerable technical and economical advance over the

prior art (Thermosol Process).

The method of the present invention is applicable to both conventional polyester

(polyethyleneglycolterephthalate) fibers and other polyesters which are known to the person

skilled in the art under the term "easy dyeable" or "carrier-free dyeable" polyester fibers, as

well as flame-resistant modified polyester fibers. This has so far been only possible for light

shades. "Carrier-free dyeable" is here understood that no carriers, i.e., components, which are

used to accelerate diffusion, are added to the dyebath. The "carrier-free dyeable polyester

fibers" are modified conventional polyester fibers, which are produced by condensing

polyethyleneglycols.


This method is also particularly suitable for dyeing woven blends of polyester and cellulosic

fibers. Cellulosic fibers include both natural fibers, such as, for example, cotton or linen, and

regenerated fibers, such as, for example, rayon or viscose, as well as esterified cellulosic

fibers, such as, for example, diacetate or triacetate.

This method permits dyeing of the aforesaid fibers in their composition as textile fabrics,

such as, for examples, fleeces, tricots or knits, but, in particular, woven fabrics. The textile

fabrics may be both flat fabrics and, particularly, pile fabrics, such as, for example, velvet,

plush or velours. The method is especially suited for dyeing polyester pile fabrics, which

heretofore could not be successfully dyed in a continuous process.

Of essential importance for the invention is the composition of the dyebath. The individual

operations for application of the dyebath, such as immersion, padding, spraying, scraping on,

application of foam, impregnation; and the subsequent treatments, such as steaming,

washing, and drying are per se conventional steps and employ known types of apparatus, as

are described for example in M. Peter, "Grundlagen der Textilveredelung" [Basics of Textile

Finishing], 11th edition, Deutscher Fachverlag, Frankfurt, pp. 43-47 and pp. 233-237.

According to the invention, the textile fabrics are impregnated in an aqueous dyebath by

suitable application methods, such as immersion, padding, spraying, scraping on, or by the

application of foam, up to a weight increase (wet pickup) of 60 to 250%, preferably 80 to

200%, and, in particular, 80 to 160%, then directly steamed in their wet condition for 1 to 20

minutes, at 96.degree.-105.degree. C., preferably 98.degree.-102.degree. C., then again

washed several times at 20.degree. to 60.degree. C., mechanically drained and finally dried at

140.degree. to 210.degree. C., preferably 170.degree. to 200.degree. C., for 1 to 10 minutes,

preferably 2 to 8 minutes, and in particular 2 to 6 minutes.

The impregnation bath is composed of:

(a) 0 to 5 g/l (preferably 0.5 to 3.0 g/l) of a thickener;

(b) up to 150 g/l (preferably 0.05 to 150 g/l and particularly 2 to 50 g/l) commercially

available disperse dyestuffs;

(b') up to 100 g/l (preferably 0.05 to 50 g/l, and particularly 2 to 50 g/l) commercially

available direct dyestuffs;

(c) 2 to 100 g/l (preferably 5 to 60 g/l) of a partially sulfated adduct of ethylene oxide with an

alkyl phenol or C.sub.8 to C.sub.16 fatty alcohols, preferably nonylphenol or C.sub.12 fatty

alcohol with 1 to 6 mols of ethylene oxide;

(d) 0 to 60 g/l (preferably 2 to 30 g/l) nonionic or anionic surfactants, which may, for

example, comprise at least one member selected from the group consisting of alkane

sulfonates, alkylaryl sulfonates, sulfonated carboxylic acid esters, sulfonated carboxylic acid

amides, or C.sub.12 to C.sub.25 fatty acids; and preferably C.sub.12 to C.sub.14 alkane

mono-sulfonate or sodium dioctylsulfosuccinate; and


(e) 5 to 50 g/l (preferably 5 to 20 g/l) of at least one organic compound selected from the

group consisting of aromatic nitrile ethers or ethoxylated chlorophenols in emulsified form.

The dyestuffs under (b') may be used in addition to the disperse dyestuffs of (b) when the

fabric contains cellulosic fibers or yarns in addition to the polyester fibers or yarns.

Suitable thickeners may include nonionic and/or anionic products as can be derived from the

addition of ethylene oxide, from the oxidative or thermal decomposition or, respectively,

carboxymethylation of guar or locust bean powder; or cellulose, starch or algin derivatives.

Suitable thickeners include carboxymethylcellulose, carboxymethylstarch, alginates, such as

the sodium, potassium or ammonium salts of algin. Particularly suitable are products derived

from the addition of ethylene oxide as well as products with a 0.3 to 0.7 degree of

substitution.

The method of the present invention may employ any of the usual commercially available

disperse dyestuffs generally recognized as suitable for polyester. They may be used both as

dispersed powders and aqueous dispersions. Particularly suitable are disperse dyestuffs with

a relatively large molecule and of a particularly high lightfastness. The disperse dyestuffs

may be used both alone and in combination with direct dyestuffs. From a chemical

viewpoint, the disperse dyestuffs belong to the class of the azo or anthraquinone dyestuffs.

Likewise, the usual commercially available direct dyestuffs conventionally used for

cellulosic fibers may be employed in this process. They are water soluble and can belong to

the various chemical classes of dyestuffs, such as, for example, azo dyestuffs, anthraquinone

dyestuffs or metallized dyestuffs. The dyestuffs particularly suitable for the method of the

present invention, are selected by their solubility, high color absorption and high

lightfastness. Both the disperse and direct dyestuffs may contain the usual dispersing and

pulverizing assistants as well as diluent substances or salts.

Also of importance for the present method is the use of partially sulfated adducts of ethylene

oxide with alkylphenols or C.sub.8 to C.sub.16 fatty alcohols, identified above as component

(c). Preferred are partially sulfated adducts of nonylphenol or C.sub.12 fatty alcohols with 1

to 6 mols ethylene oxide. Specific examples include: the ammonium salt of a partially

sulfated adducts of nonylphenol with 5.5 mols ethylene oxide, the sodium salt of a partially

sulfated adduct of nonylphenol with 4 mols ethylene oxide, the sodium salt of a partially

sulfated adduct of a C.sub.12 fatty alcohol with 2 mols ethylene oxide, the ammonium salt of

a partially sulfated adduct of nonylphenol with 2.5 mols ethylene oxide, and the ammonium

salt of a partially sulfated adduct of octylphenol with 6 mols ethylene oxide.

These products are obtained by the partial sulfation of the adducts from ethylene oxide with

alkyl phenols or fatty alcohols respectively. The degree of the ethoxylation and sulfation may

widely vary, and the products are obtained in the form of their ammonium or alkali, in

particular sodium, salts. The component (c) acts as an emulsifier and dispersant for the dyes

and can be directly added to the dyebath.


The dyebath also desirably includes anionic and nonionic surfactants, identified above as

component (d). Suitable surfactants may be selected from ammonium or alkali metal salts of

alkane sulfonates, sulfonated carboxylic acid esters, or sulfonated carboxylic acid amides.

Preferred are C.sub.12 to C.sub.14 alkane monosulfonates or sodium dioctylsulfosuccinate.

Specific examples include: the sodium salt of sulfosuccinic acid 2-ethylhexylester, the

sodium salt of C.sub.12 to C.sub.16 alkanesulfonate, and the sodium salt of sulfosuccinic

acid C.sub.12 hemi-amide.

These, in general, are wetting agents which are known to the person skilled in the art under

the description of rapid wetting agents. In the method of this invention, these agents serve as

wetting agents during the application stage and also serve to generate foam in the steaming

stage to promote level and even dyeing, especially of pile fabrics. Chemically, they are

C.sub.12 to C.sub.16 alkane sulfonates, monoesters and diesters of sulfosuccinic acid, or

monoamides or diamides of sulfosuccinic acid. The component (d) can be directly added to

the dyebath. Also suitable are ammonium or alkali metal salts of alkylarylsulfonates, such as

sodium dodecyl benzenesulfonate; ammonium or alkali metal salts of lauryl sulfonate, such

as sodium lauryl sulfonate; ammonium or alkali metal salts of ethylene oxide adducts of

lauryl sulfonate, such as the sodium salt of the addition of 1 to 6 mols of ethylene oxide to

lauryl sulfonate; and ammonium or alkali metal salts of ethylene oxide adducts of C.sub.12 to

C.sub.25 fatty acids, an example of which is the adduct of 9 to 50 mols of ethylene oxide to

octadecanoic acid.

Component (e) as described above may comprise accelerators based on aromatic nitrile

ethers or ethoxylated chlorophenols in emulsified form, in particular, benzyloxypropionitrile,

chlorobenzyloxypropionitrile and methylbenzyloxypropionitrile, as well as di- and

triethylene glycol monochlorophenyl ether. Preferably the nitrile ethers have a molecular

weight of 100 to 250, in particular, 150 to 200, and that of the ethoxylated chlorophenols

ranges from 150 to 400, in particular from 200 to 300.

These products are water insoluble, high-boiling liquids, which are capable of softening the

polyester fibers under the conditions of the method according to the invention. Therefore,

they make possible and accelerate the diffusion of the disperse dyes into the polyester fibers.

Commercially available products of component (e) are either pure substances or contain

emulsifiers. Pure substances are added with the aforesaid assistants to the padding liquors in

emulsified form. Particularly suitable components (e) for the present method are di- and

triethyleneglycol monochlorophenyl ethers and benzyloxypropionitrile. Preferred emulsifiers

for the component (e) are ethoxylated C.sub.16 to C.sub.18 fatty alcohols with 10 to 25 mols

ethylene oxide.

The described assistants (c), (d), and (e) can be used both alone and combined with each

other, and the sum of the quantities used can vary from about 2 to about 200 g/l of the

dyebath.

Aside from the aforesaid ingredients, the dyebath may contain additional assistants, such as

dispersing agents, wetting agents, antistatic agents and defoamers.


The following examples are intended to describe the invention in more detail, but not to limit

it.

EXAMPLE 1

A raschel plush product of polyester (Trevira 220) was impregnated in a bath containing:

2.0 g/l modified guar powder (modified by thermal decomposition)

2.3 g/l Polyester Yellow LS (trade name)

0.59 g/l Polyester Brilliant Red BS (trade name)

0.3 g/l Polyester Violet 2RB (trade name)

1.23 g/l Polyester Blue 6102 (trade name)

25.0 g/l Ammonium salt of a partially sulfated adduct of nonylphenol with 5.5 mols ethylene

oxide;

10.0 g/l Sodium salt of the sulfosuccinic acid 2-ethylhexyl ester;

15.0 g/l Benzyloxypropionitrile.

The material was impregnated on a padder with a 95% absorption of the bath. The product

was then steamed for 10 minutes at 99.degree. C. in a saturated vapor atmosphere, and

subsequently washed five times in 30.degree. C. water.

The material was then drained by squeezing to 75% residual moisture, and finally dried for 3

minutes on a tenter at 180.degree. C. A grey, very uniform pile fabric was obtained with

suitable lightfastness and good general fastnesses to rubbing (crocking) and washing.

EXAMPLE 2

A pile fabric consisting of (55%) polyethyleneglycoltherephthalate fibers in the pile and

(45%) cotton in the backing was preset for 40 seconds at 190.degree. C. Then, the fabric was

impregnated by padding with a liquor consisting of:

2.5 g/l locust bean powder ethoxylated with 1.5 mols ethylene oxide per OH group.


12.0 g/l Polyester Yellow 7102 (trade name)



8.0 g/l Polyester Rubin GL (trade name)


3.64 g/l Sirus Light Orange GGL (trade name)

4.55 g/l Direct Bordeaux BS (trade name)

3.18 g/l Solamin Blue VGRL 167% (trade name)

40.0 g/l Sodium salt of a partially sulfated adduct of nonylphenol with 4 mols ethylene oxide

18.0 g/l Sodium salt of sulfosuccinic acid 2-ethylhexyl ester

30.0 g/l Benzyloxypropionitrile.

The absorption of the bath amounted to 98%.

The fabric was then steamed for 15 minutes at 98.degree. C. in a saturated vapor atmosphere,

then washed three times in 50.degree. C. water, mechanically drained to 75% residual

moisture, and dried for 2.5 minutes on a tenter at 190.degree. C. The result was a dark red,

uniformly dyed pile fabric with good fastnesses and a lightfastness of 7. The lightfastness

was determined in all examples according to both the Opel Standards GME 60292 of 11/77

and by the FAKRA test.

EXAMPLE 3

A woven velour of 55% polyester, 35% cotton and 10% rayon was impregnated by applying

foam from a bath with the following ingredients (80% absorption of the bath):

3.5 g/l water soluble guar derivative (1.0 mol ethylene oxide per OH group)




1.05 g/l Polyester Blue BGL (trade name)

2.5 g/l Superlightfast Yellow EFC (trade name)

1.5 g/l Sirius Red F3B 200% (trade name)

1.25 g/l Sirius Light Grey CGLL 167% (trade name)

20.0 g/l Sodium salt of a partially sulfated adduct of a C.sub.12 fatty alcohol with 2 mols


ethylene oxide

5.0 g/l Sodium salt of a C.sub.12 to C.sub.16 alkane sulfonate

15.0 g/l3-chlorophenol triethyleneglycol ether.

Following its impregnation, the material was steamed for 8 minutes in a saturated vapor at

100.degree. C., washed four times in 50.degree. C. water, mechanically drained to 80%

residual moisture and dried for 2 minutes at 200.degree. C. The result was a light brown,

completely uniformly dyed product with excellent fastnesses.

EXAMPLE 4

A plush fabric with polyester pile and a cotton and triacetate blend in the backing was

impregnated in the following bath:

1.5 g/l Anionically modified guar powder (degree of carboxylation 0.53)




2.6 g/l Solamin Blue VGRL 167% (trade name)

1.8 g/l Sirius Light Blue BRR 182% (trade name)

0.49 g/l Sirius Light Orange GGL (trade name)

0.77 g/l Sirius Light Brown R (trade name)

60.0 g/l NH.sub.4 salt of a partially sulfated adduct of nonylphenol with 2.5 mols ethylene

oxide

20.0 g/l Sodium salt of sulfosuccinic acid C.sub.12 hemi-amide

30.0 g/l emulsifier-containing methylbenzyloxypropionitrile.

Impregnation was done on a two-roller padder with 100% absorption of the bath. Then the

material was steamed in its wet condition for 14 minutes in a 98.degree. C. saturated vapor

atmosphere, subsequently continuously washed in 5 baths at 45.degree. C., and drained by

squeezing to 65% residual moisture, and finally dried for 4 minutes on a 6-section tenter at

185.degree. C. The result was a medium to dark blue, uniform coloration with a lightfastness

of 7 and very good general fastnesses.


EXAMPLE 5

A liquor consisting of

4.5 g/l carboxylated guar derivative (degree of carboxylation 0.40)




1.05 g/l Polyester Blue BGL (trade name)

2.5 g/l Superlightfast Yellow EFC (trade name)

1.5 g/l Sirius Red F3B 200% (trade name)

1.25 g/l Sirius Light Grey CGLL 167% (trade name)

35.0 g/l NH.sub.4 salt of a partially sulfated adduct of octylphenol with 6 mols ethylene

oxide

10.0 g/l Chlorobenzyloxypropionitrile

was scraped with a 200% absorption of the bath on a tricot of 70% carrier-free dyeable

polyester, 20% cotton, and 10% rayon, which was then steamed for 15 minutes at 98.degree.

C. It was then washed three times at 45.degree. C. and drained to 80% residual moisture, and

finally dried for 8 minutes at 160.degree. C. The result was a blue grey, uniform coloration

with excellent fastnesses. The lightfastness according to the so-called "Opel Test" ranged

from 6 to 7.

EXAMPLE 6

A tricot product of 100 percent polyester was preset for 45 seconds at 180.degree. C. Then

the fabric was impregnated by padding with a liquor consisting of:

2 g/l Locust bean powder

15 g/l Polyester Brilliant Red BS (trade name)

4 g/l Polyester Rubin GL (trade name)


50 g/l Sodium salt of a partially sulfated adduct of nonylphenol with 4 mols ethylene oxide

25 g/l Sodium salt of sulfosuccinic acid 2-ethylhexyl ester

ContinouContinouContinouContinous dyeings dyeings dyeings dyeing 53535353

25 g/l Benzyloxypropionitrile

The absorption of the bath amounts to 86%. The fabric was steamed for 9 minutes at

99.degree. C. in a saturated vapor atmosphere and then washed three times in 50.degree. C.

water, mechanically drained to 80% residual moisture, and dried for 2 minutes on a tenter at

180.degree. C. The result was a dark red, uniformly dyed fabric with good fastness.


Pad-thermosol

It is a machine which is used to pad, dry and cure to all kinds of fabrics. This machine is

categorized under continuous process of dyeing.

Machine details of pad-thermosol:

Pad-thermosol consists of following parts that dye and guide the fabric during dyeing,

• Batcher

• Guide rollers

• Screy

• Cooling drum

• Cooling jacket

• Trough

• Squeezing rollers

• Padder

• VTG rollers

• IR-dryers

• Drying chambers

• Radiator

• Heat exchanger

• Curing chamber

• Piller

Now we will see these parts individually by using figures.

Batcher: When the fabric is taken to dye , it is in the form of batcher that is taken after

mercerizing as shown in the following fig.


The fabric width depends on the size of the batcher and the fabric of different length is

winded on it . This length may vary from 100 to 70,000 meters.

Guide rollers: These are the rollers which are used to guide the fabric from different paths. Their

function is only to direct the fabric toward it’s outlet. Guide rollers are shown in the

following fig.

Cooling drums: When the fabric is taken from the mercerization then it’s temperature is more

than the limit. In this state the fabric cannot be react properly with dye in the trough. So we

use cooling drums in which water is circulating and the temperature of fabric is decreasing

gradually. Their diameter is large as cpare to other rollers that is ranges from 26’’ to 30’’.

Cooling jacket: This jacket has very important role in cooling the dye bath. It is necessary

because in hot form dye cannot react with the fabric. Cool water circulate within this jacket


Trough: It is the first main part of this machine. This part is filled with liquor which is filled

with dyes and chemicals . it’s capacity is nearly 1400lilres. It is dozed manually as well as

automatically. The dozing structure is shown in the following fig.

The temperature of this bath is room temp. the fabric capacity is 1-1.5m within this dye bath

or trough.following recipe is used in this trough,

• Dyes

• Urea (moisturizing agent)

• Soda ash( for reactive dyes)

• Sodium bicarbonate(for pigments)

• Primazol FFAM (anti-migrating agent)

• NF

Cooling jacket: It is a jacket that is used in outer side of the trough. This jacket is used to make

the temperature of liquor cool down , because if it will not cool down then the dye liquor

will not react properly.

Squeezing rollers; These rollers have function just to squeeze the fabric which is dipped in dye

bath. In this way dye can react completely with the fabric. It is a pair of roller that moves in

opposite direction and squeeze the dyed fabric. They are rubber coated and have diameter

8’’.


Padder This is the main part of the machine. All the pick-up of dye depends upon the padder.

It is a pair of two rollers. Two rollers move in opposite direction to each other. These rollers

are also rubber coated but have special type. L-C-R (left-center-right). This is the most

sensitive factor that require more concentration than any other part. Basically L-C-R fault

means that the fabric dye is varying from left,right and center. The structure of padder is

shown in the following fig.

We can say that there are three parts of padder on which pressure is adjusted to avoid L-C-R

fault. This pressure varies according to the width of the fabric and pickup of dye. Usually

pick-up is 60%.


VTG-rollers:

These are called vertical tentioner guide rollers . These are the rollers that give

tension and rest to the dyed fabric and fabric contact with air. There are 9 rollers that are used

for this purpose,5 above(driver) and 4 down (driven). The structural diagram is shown in the

following fig.

These rollers contain 9-10 m fabric within their area. The time taken by the fabric on these

rollers is 10-12seconds.

IR dryers:

These are called infra red dryers. IR-dryers are also called pre-dryers. 30% of fabric is dry

in this section. The temperature of these dryers vary from 1000-1300C. these dryers have

very important role in dyeing the fabric uniformly. The fig. of IR is shown as follows,

When the fabric is passed from the padder then there is an uneven dyeing that cause the face-

back problem on the fabric. The structural diagrame of the dye particles shown in the figure

after padding as


Two IR are used for heavy quality and one is used for light quality.And when the fabric is

passed through the IR dryers the dye par2ticles migrate from surface to the core of the fabric

with help of infra red rays. After passing through IR the the dye particles are shown bellow

on the fabric surface,

Drying chambers:

There are two drying chambers used for thermosoling .These are the

chambers where thermosoling is done. The fabric passes through the rollers in the chamber

and thermoil react with fabric in these chambers. The diagram is shown in the following fig.

The thermoil is given to the chambers in pipes attatched to the radiator and it circulates

within the chamber with the help of circulating fans. The fig. of heat exchanger is shown in

the following fig


The temperature of these dryers vary with quality of the fabric and dye stuff used because

different dye stuff have different range of temperature for it’s fixation , 20% fabric is dry in

these chambers. The temperatures of some quality and dye stuff are given bellow.

For four chambers,

Shade sea isle

Quality 16*12/84*26

Speed 40m/min

Temperature 110C 125C

Dye stuff Vat (cibanon)

Quality 18*18/60*60

Speed 40m/min


Dye stuff Vat

Quality 20*10/72*28

Speed 40m/min


Dye stuff Reactive (remazol)

For three chambers,

Quality 16*16/60*60

Speed 30m/min



ContiContiContiContinous dyeingnous dyeingnous dyeingnous dyeing 61616161

Curing chambers

There are two chambers that are responsible for the curing process. Curing

chambers are used for the fixation of the dye into the fibre.These are the chambers where

remaining fabric is dry i.e 50%. As there is more temperature within these chambers so we

need moisturizing agent that produce the humidity within the chambers and the fixation

process is carried out. For producing the moisture we use urea as a moisturizing agent. This

chemical is mixed with the dye recipe in the trough. The curing chambers are shown as

follows,

Like drying chambers these chambers also have different temperature according to the dye

stuff and quality of the fabric. Some temperatures are shown as,

For four chambers,

Shade sea isle

Quality 16*12/84*26

Speed 40m/min


Dye stuff Vat (cibanon)

Quality 18*18/60*60

Speed 40m/min


Dye stuff Vat

Quality 20*10/72*28

Speed 40m/min




For three chambers,

Quality 16*16/60*60

Speed 30m/min

Temperature 165C


Pillers :

This is a device that convert the straight fabric into pile form. It is used for he trolly

outlet. If there is batcher at delivery then it is not used, but usually trolly is used after screy.

Light box:

When the fabric is delivering then it is checked in a light box after 500m or 700m

depends on the requirement. L-C-R (left-center-right) of the fabric is checked in this box to

avoid shade variation from all sides. There are few kinds of lights under which fabric is

checked ,it is also depends on the requirement of the customer.

Day light

D-65

Sun light

Ultra voilet

Flouricent light


Pad-steam

It is a machine that can dye ,steam and wash the fabric. It is an omportant part of continous

dyeing . when the fabric is dyed then washing is required so we use pad-steam after

thermosol range. In case of polyester/ cellulose blended fabrics we use this machine for

developing,steaming and washing of the fabric.

Parts of machine

There are following parts of machine that are responsible to handle the fabric during pad-

steam processing,

• Screy

• Cooling cylinders

• Padder

• Trough

• Steamer

• Washing boxes

• Drying cylinders

Some parts are studied in pad-thermosol topic remainings are given as follows,

Steamer:

It comes right after padder It is a main part of the machine which is used for steam the

dyed fabric. The temperature of this section is 100°C. the fabric remains here according to

the dye stuff given as follows

Direct dyes 60sec

Vat dyes 30-40sec.(103-105 °C)

Pigment dyes not required

Reactive dyes 40-6-sec (102-110°C)

Sulpher dyes 30-45sec (102-110°C)

Combination of 30-40sec.(102-105 °C)

disperse and

vat dyes

Combination of 30-40sec.(102-105 °C)

disperse and

reactive dyes


Washers:

There different amount of boxes in different machines prepared by the companies. These

washers are suitable for

Washing

Rinsing

Soaping

Oxidation

Soaping is necessary to remove unfix dye particles from the fabric and then it is washed.

Oxidation is the process in which the vat dyes are developed. In first padder reduction is

done and in second padder of pad-steam oxidation is carried out to resize the dye particle of

vat dyes. That is why vat dyes have very good washing fastness.

The temperature of these washres are set according to the process and dye stuff. It will

discuss in last topic.

Objectives of the washing concept and recycling systems The most important objectives during the realisation of the new washing concept are

reduction of the wastewater load (COD) and simultaneously lowering washing water and

steam consumption. Referred to here is the water consumption of the entire system and not

that of the washing machine alone. In spite of the latest washing machine technology and

already extremely low water consumption values, further significant reduction of the

effective water consumption can be still achieved by wastewater circulation. Recycling the

wastewater is therefore an important derivative of the main objectives. A further objective of

this project, originating from the fact that re-using the wastewater requires the impurities to

be separated from the water, was to produce concentrates. Concentrates can be produced

either directly at the place of origin (washing machine) or indirectly on the membrane plant.

The concentrate quantities formed should be small and thermal disposal should be possible.

Large quantities of effluent sludge are undesirable.

The machine concept The installation referred to is a BENNINGER high-efficiency washing machine, operating

with the counter flow principle. This means that the fabric and the washing water flow in

opposite directions. The machine concept includes the following standard modules:

· High humidity impregnation (with variable liquor application)

· Bi-functional Reacta roller-steamer, used as either a washing compartment for pre-washing

the dyed fabric or as a steamer for pre-treatment processes

· 6 vertical roller vat washing compartments with Extracta lay-on rollers

· 2 Hydrovac vacuum suction stations

The special features of this technology lie in the combination and operation of the

components and the design of the washing liquor guidance


The BENNINGER EXTRACTA roller vat high-efficiency washing machine is especially

suitable for counter flow washing since each washing compartment contains up to 7

additional washing chambers (fig. 2). The fabric is squeezed through pneumatically loaded

lay-on rollers situated between each washing chamber. The washing liquor meanders within

the compartment according to the counter flow principle, meaning that the liquor flow is

guided in the opposite direction to the fabric run. This method of processing results in a high

concentration of wastewater ingredients accumulating contrary to the fabric run. Other well

known washing system such as horizontal or diagonal washing machines, which circulate the

liquor, are not suitable for this application because there are only a max. of 2 chambers per

washing compartment. The concentration variations in the washing water are therefore

considerably less.

Fig. 1: High-efficiency washing machine with bi-functional steamer

The parameters of the washing machine can be set at will and are maintained thanks to the

modern control system. This enables the various tasks in respect of water, counter flow and

process guidance to be realised.

Process concepts The following process steps occur:

· Continuous desizing taking into account the aspects of the separation

and utilisation of highly concentrated partial flows e.g. sizing agent

recovery

· Continuous and/or semi-continuous bleaching and scouring with the

premise of the partial flow separation and efficient utilisation and

recovery of wastewater

· Extremely low water consumption when washing out dyes,

separating concentrates and re-introducing washing water into

circulation.


Pre-treatment process The last three washing compartments in the pre-treatment process are operated in the

classical form. The washing water flows through these three compartments in counter flow.

A defined partial flow is taken from the overflow and fed into the washing compartments in

the front area of the installation. This partial flow serves to re-concentrate and determines the

amount of sizing concentrate produced during the pre-treatment. A counter flow of washing

water passes through the front washing compartments again. Another part of this highly

concentrated washing water is applied to the fabric at the intake of the machine using a high

pick up application aggregate.

The fabric then reaches the steamer. The sizing agent swells in the steamer and the viscosity

of the swollen sizing agent is reduced. Immediately after leaving the steamer, the fabric

passes over the first suction bars where the size concentrate is extracted. The concentrate is

fed into the water seal of the steamer, which operates on the overflow principle. The

concentrate accumulated via the overflow represents the volume available for recycling or for

re-use.

The amount is determined and controlled according to the portion taken out of the last three

washing compartments. This ensures that the process conditions and parameters are

maintained. The pre-treatment or de-sizing can be carried out in two different processes:

· Cold store bleaching with oxidative de-sizing.

· De-sizing with water soluble sizing agent: De-sizing takes place directly in the washing

machine. The advantages of this process lie in the fact that the fabric is dry when it enters the

machine and wet when it leaves the washing machine. This moisture is removed from the

process and therefore reduces the accumulation of wastewater. In addition, the sizing agent

has not been modified or degraded and can therefore be recycled.

The concentrate that accumulates during the pre-treatment is collected in a separate container

and then fed into a specially developed evaporator The concentrate is evaporated and the

residual solids then removed. This is, in principle, a two-step roller dryer. A small part of a

heated roller is immersed in the liquid and coated with a film of concentrate. The first step is

to increase the concentration of the sizing concentrate. The second step is the complete

evaporation of the water and the subsequent removal of the dried residual solids with a

scraper. Thermal disposal is carried out on the residual solids.

Washing out reactive dyes During the washing out process all compartments, as well as the steamer, operate as a

washing compartment. The steamer operates with cold water flowing in counterflow in order

to wash out the bulk of the unfixed dyes and residual alkalis from the fabric. The fabric is

then passed over the first suction bars, extracting as much moisture as possible, in order to

achieve a good bath separation. A second suction bar, situated after the first washing

compartment, boosts this effect. The subsequent washing compartments operate with hot

water.


The use of the Hydrovac vacuum results in a reduced water consumption because the highly

concentrated hydrolyzates have already been extracted from the fibre core and removed in

the pre-rinsing process.

The wastewater from the washing out process passes

through the multistage membrane plant and is purified

making it fit to re-introduce into the system.

The coloured wastewater is collected in a container and

then pumped to the membrane plant. The concentration

of impurities (dyes, salts, fibre accompanying substance

etc.) is increased in the multistage membrane plant and

the washing water recycled. The clean water is

reintroduced into the production as warm process water.

This saves both time and energy. The liquid dye

concentrate is evaporated to form a solid and recycled

in a thermal process.

Roller evaporator (source: photo ex-works Van Clewe) for the

recovery of solids in pre-treatment wastewater

Another option is a new electrochemical process in which the dye concentrate is decolourised

and subsequently released into the communal sewage.

Results

De-sizing / Pre-treatment

Thanks to the partial liquor flow

guidance on the BENNINGER

washing machine, only 0.5 - 0.7 l of

effluent per kg of textile is

generated. This partial effluent flow

contains up to 90% of the COD load

from the pre-treatment process. An

even higher 95% COD retention

was attained using water-soluble

sizing agents.

The small volume facilitates evaporation directly at the place of origin. This suits VAN

CLEWE, from an economical and ecological point of view, because it is cheaper than

treatment at the

municipal sewage plant. Van Clewe increases the solvent concentration in the roller

evaporator, as described above, and then recycles the residual solids in a thermal disposal.

Table 1 lists the material balances and liquor flows.

Continous dyeinContinous dyeinContinous dyeinContinous dyeingggg 66668888

The possibility of disposing of concentrate in a liquid form or reducing it to solids depends

on the regional circumstances. Official regulations or the capacity and suitability of

municipal sewage plants are of vital importance

The regional environmental circumstances are taken into account early in the project phase.

Only a specific adaptation of the concept and machine guarantees the expected success.

Washing out dyes

The BENNINGER high-efficiency washing machine EXTRACTA, with integrated Hydrovac

vacuum system, has been successful in washing light nuances with only 1, 5 l/kg (0,5 l/kg

cold; 1,0 l/kg hot) instead of the previous 7 l/kg used in a conventional washing machine.

Today, medium shades require 3,0 (1,0 + 2,0) l/kg and dark shade fabrics 4,5 (1,5 + 3,0) l/kg

instead of 8 - 10 l/kg. Very dark shades, such as black and dark blue, which normally

required 12 l/kg, are today washed with only 6 l/kg.

The water quantities were optimised by visually inspecting the washing water in each

compartment . Simultaneously, extracted samples of the textile were analysed and a

correlation of the fastness level established.

The impurities in the equation remain the same, however the considerably lower amount of

washing water results in significant energy savings in the form of steam required for the

washing process.

The washing water is fed into a multistage membrane plant. The smaller quantities of water

also allow the utilisation of a smaller plant compared to that found in conventional washing

systems. The result is a greatly reduced investment and a drop in electrical energy

consumption of the membrane plant, leading to lower running costs of the entire processing

system.

The multistage membrane plant consists primarily of an

ultra-filtration ( with an ensuing nanofiltration and/or reverse

osmosis. The ultra-filtration is fitted with a special ceramic

membrane. This membrane filters out particles and long-

chain organic molecules from the wastewater up to a

temperature 95°C. The ensuing nanofiltration and/or reverse

osmosis remove almost all the dissolved dyes and salts from

the water. The purified process wastewater can be

reintroduced into all areas of textile finishing without

negatively affecting the end product.

The membrane plant has been in continuous, near to failure-

free, operation with practically no personnel expenditure for

more than 5 years.

Sampling at the EXTRACTA open

width washing machine (source: photo ex-works Van

Clewe)

Using a combination of ultra-filtration and reversed osmosis can result in a recycling rate of

more than 80% of the wastewater. The recycled process wastewater is decolourised after


treatment with the membrane plant, has a COD value of approx. 100 to 300 mg/l and a

conductibility of approx. 100 µS/cm.

Future prospects The extent of the successful reduction of the flow volumes during pre-treatment and washing

out dyes is impressive. The COD load in the wastewater has been reduced by 90 - 95 %. All

the water from the washing out process can be re-introduced into circulation. This has

allowed the effective water consumption needed to process one kg of fabric to be reduced to

1/7 of what is conventionally required.

Further economical and ecological optimisation accomplished was:

· Recycling the sizing agent

· Decolourising of dye concentrate from the padder chassis and the membrane plant

The recycling of the sizing agent is dependent upon the manner in

which the company produces. Experience has shown that it is only

viable for vertical companies (own weaving and textile finishing) to

recycle the sizing agent. This is due to the fact that the sizing recipes of

external weavers is not always known to remunerated finishers,

whereas Van Clewe supplies weaving mills with sized warps.

Recycling the sizing agent is therefore possible. Van Clewe is

presently examining the circumstances with regard to their feasibility

and cost. Initial trials have shown that in such cases, processing can be

carried out with almost no wastewater.

In one article, the accumulated sizing concentrate is increased by

adding 10 % of fresh sizing agent and then re-introduced directly into

their own sizing department.

Today, decolourising dye concentrate from the dye liquor and the

membrane plant by way of electrochemical reduction is a fully

developed

Fig. 6: Ultra-filtration installation (Q = 10

m3/h)

and economically interesting process. The costs are approx. € 2.50,-- per m3 concentrate.

Decolourising the concentrate can, depending on the dye combination, constitute 70 - 90 %

of the initial dye value (DFZ). When considering a medium-sized textile finishing company

with 2 CPB dye stations, which today accumulates between 0.8 - 1.0 m3 of concentrate from

the padder chassis and the membrane plant each day, one finds that the decolourising costs

are virtually negligible. This technology has been developed by the Textile Institute in

Dornbirn (Austria), Dystar and BENNINGER Ltd as a solution to decolourise dye

concentrate without producing any additional by-products such as effluent sludge and

chlorine.


Dyeing processes

There are three types of processes in dyeing given as,

• Exhaust dyeing

• Semi-continous dyeing

• Continous dyeing

Exhaust dyeing:

In this type of process the dye move from the dye bath liquor onto the fibre in a

set time. During that time , it diffuses or migrates into the structure of the fibre, and is fixed.

Exhaust dyeing is used for loose stock (fibres), yarns , fabrics and garments. The method of

dyeing may include the following machines,

Jet dyeing

Jigger dyeing machine

Beam dyeing

And small to medium sized batches can be processed using this method.

Semi-continous dyeing:

In this type of dyeing the material may be padded with the dye solution on

mangle and finished off on a jigg.

Continous dyeing:

In this method the material may be passed through a trough of dye liquor .

After passing it through liquor then it is passed through a pair of squeezing rollers that

squeeze the excess liquor from the material. The lower the percentage pick-up , the higher

the concentration if the liquor can be achieved. For this purpose pad-thermosol and pad

steam is used to dye the material in continous dyeing range.


Difference between Batchwise Dyeing and Continous

Dyeing

There are different advantages and disadvantages both methods have. Following is the

difference between them.

Batch-wise dyeing continous dyeing

Method of applyeing dyes and in same bath in separate baths

Chemicals

Liquor ratio long short

______________________________________________________________________

Reaction of fibre or rate of slow rate higher rate

Absorbtion

______________________________________________________________________

Ratio of contact exchange better to be higher better no to exchange

b/w fibre and dye

______________________________________________________________________

Padding solution gradually change constant

______________________________________________________________________

Mechanical and physical stepwise change in temp. all conditions kept constant

solution

______________________________________________________________________

Equipment required for each one machine for all special equipments

Process processes for each process

______________________________________________________________________

Costs of equipment relatively cheap expensive

______________________________________________________________________

Processing efficiency low high

______________________________________________________________________

Irregular performance of possible to cover in impossible

Equipments certain degree

______________________________________________________________________

Quality of dyeing excellent slightly inferior

______________________________________________________________________


Dye stuff used for continous dyeing

There are different types of dye stuff used in continous dyeing. Each dye stuff has it’s own

reaction and behavior with fabric . Some have good washing fastness and some has low

washing fastness, some has high priced value and some are cheaper.

Dyes for cotton and other cellulosic fibres

� Direct dyes

� Azoic dyes

� Reactive dyes

� Vat dyes

� Sulphur dyes

Dyes for protein fibres

� Acid dyes

� Reactive dyes

� Metal complex

� Mordant(chrome)

Dyes for synthetic fibres

� Disperse dyes

� Basic dyes

� Acid dyes


Details of some dye stuff

Dye class name manufacturers

1-VAT DYES Indanthrene DK-blue 5508 dyes star

Grey 5607 dyes star

Red FBB dyes star

Yellow 3R dyes star

Brown BR dyes star

Olive MW dyes star

Cibanon olive S (784/kg) ciba

Brown BR(1104/kg) ciba

Yellow 3R(1651/kg) ciba

Green BF ciba

China olive T china Olive R china

Olive MW china

Olive green B china

2-PIGMENTS imperon yellow K-R dye star

RedK-B(914/kg) dye star

Green K-G dye star

Blue K-B dye star

DK-Brown dye star

Black RT BASF

3-SULPHER DYES Sulpher Black BR

Khaki

Green

Yellow GR

Brown

4- DISPERSE Foron yellow SRLP clarient

Navy S2GRL

Black S2BLS

Rubine S3GFL

Dianex black ccR dye star

Royal blue

Rubine cc

Yellow brown ser


Navy cc

Navy SG

Terq SBG

Yellow S4G

5- REACTIVE DYES Rem terq blue G dye star

Red RB

Blue BB

Yellow 3RS (276/KG)

Black N

Black B

Orange 3R

Cibacron grey GE(1249/kg) ciba

Brown P6R

Yellow P2RN

Navy C-R

Blue PB

Blue P6B

Red C-2BL

Terq P-GR

Jakazol black N ind

Drim. Navy KGRL clarient

Yellow K2R

Orange KGL

Yellow 3G


CHEMICALS

NAME PURPOSE

Burst 100 (ciba speciality chem..) use as an anti foam

Formic acid use to maintain the PH

Oxalic acid fluff cleaning

Acetic acid use to maintain the PH and neutralization

Albegin A to strip the dyes

Glosperse N 330 soap, washing

Sod. Suphide reduction of sulpher dyes

Sod. Bicarbonate PH controle, for exaution of dyes

H2O2 oxidation of VAT dyes

NAHCO3 bleaching agent

Sirrex 2ud buffering agent

Algenate anti-migrating agent

Sitamol BL dispersing agent (87/kg)

Primazol FFAM Anti migrating agent(46.5/kg)

Irgazol VAT dispersing agent

Primazol NF wetting agent(192/kg)

Hydro N

Hydro B

NaCl for dye exaution on pad steam

Glauber salt control bleaching of dyes

Kola sol. Ind D. agent

Per anti foam AF150 anti foam

Mera pan DPE D. agent

Ultra print RG mild oxidizing agent

Urea NH2CONH2 PH maintain, also for fixation of dyes

Soda ash fixation of dyes

RD-13 srtipping agent

Helizarin binder CEO for binding pigments

K2Cr2O7 oxidation of sulpher dyes

Colla sol. Anti dusting agent


Cellulose fibres can be dyed with a wide range of dyestuffs, namely:

· Reactive

· Direct

· Vat

· Sulphur

· Azoic (naphtol).

Reactive dyes

Vinyl Sulfone dyes, also known as Remazol® dyes after the trademarked name under which

they were first introduced, are a type of fiber reactive dye that is often used in silk painting.

Although silk paintings made with vinyl sulfone dyes are usually steamed to set the dye, the

dyes can also be "batch cured" at warm room temperatures.

Unlike some fiber reactive dyes, vinyl sulfones can be used as true reactive dyes on cotton,

silk, AND wool. Of course, wool must never be subjected to the high pHs used in dyeing

cotton, and it requires high heat, unlike cotton. Like all dyes that work on cotton, vinyl

sulfones can also be used on linen, hemp, and other cellulose (plant) fibers.

Vinyl sulfone dyes are a type of fiber reactive dye that is less reactive than, for example,

Procion MX dyes, and thus they both last longer in solution in water, and require more heat

for the reaction with the fiber. This means that they can actually be purchased already

dissolved in water, unlike Procion MX or Cibacron F dyes, eliminating the one slightly

hazardous step of working with powdered dyes.

The lower reactivity of Vinyl sulfones is not the whole story, however. Unlike Drimarene K

and Cibacron F dye, Vinyl sulfones contain a 'masking' group, on the reactive part of the

molecule, which prevents them from reacting with the dye water until it is removed. This

makes the dyes much longer lasting in water! The masking group of at least some of the

Remazols can be removed at high pH (i.e, with soda ash or pot ash or sodium silicate), which

is suitable for cotton, or, if the dye solution is heated to a high enough temperature, at mildly

acid pH, which is suitable for wool. The latter is a slower process.


About the Chemistry of the Vinyl Sulfone dyes

Here is a quote from Cellulosics Dyeing (ed. John Shore, 1995, Society of Dyers and

Colourists), p 200:

The Remazol (Hoesht) vinylsulfone dyes, containing the characteristic 2-

suphatoethylsulphonyl precursor grouping, are intermediate in reactivity between the high-

reactivity heterocyclic systems, such as dichlorotriazone [Procion MX type] or

difluropyrimidine, and the low-reactivity ranges, such as aminochlorotriazine [Procion H] or

trichloropyrimidine. Exhaust dyeing temperatures between 40 and 60 degrees C may be

chosen, depending on pH, since caustic soda [NaOH?] is often selected to bring about

alkaline hydrolysis of the precursor sulphate ester. [Use "ph"s if you're British, "f"s if

American.] These dyes are applicable by a wide variety of batchwise and continuous

processes. The substantivity [tendency to cling to the fiber even when unreacted] of many of

these dyes is markedly lower than that of typical haloheterocycloic dyes [eg Procion MX or

Cibacron F]. Not only has the vinylsulphone group, unlike the heterocyclic ring systems,

little if any inherent affinity for cellulose, but the terminal sulphato group enhances the

aqueous solubility of the precursor form before 1,2-elimination to the vinylsulphone. In

contrast to the haloheterocyclic systems, the dye-fibre bonds formed by the vinylsulphone

dyes are at their weakest under alkaline conditions.

I.e., use temperatures between 40 and 60 C (104 and 140 F), and use alkaline conditions

(high pH, as usual with fiber reactive dyes). High pH *might* work for discharging. Should

resist acid perspiration better than Procion MX or Cibacron F dyes, if that's a problem for

you. Should be vastly easier to wash out of the fabric than Procion MX or Cibacron F dyes.

One third of dyes used for cellulose fibres today are reactive dyes. They are mostly applied

according to the pad-batch and continuous processes for woven fabric, while batch processes

are the most common for knitted fabric, loose stock and yarn.

In batch dyeing, dye, alkali (sodium hydroxide or sodium carbonate or bicarbonate) and salt

are added to the dye bath in one step, at the start of the process, or stepwise. In the stepwise

process the alkali is added only after the dye has absorbed to the fibre. Its amount is

determined by the reactivity of the system and the desired depth of shade (cold dyers are

applied at lower pH compared to warm and hot dyers). Salt is added to improve bath

exhaustion: the concentration employed depends on the substantivity of the dye and on the

intensity of the shade. Higher concentrations are required for deep shades and low-affinity

dyes, as shown in the table below.

Shade High-affinity dyes Low-affinity dyes

<0.5 %

>4 %

10 - 30 g/l NaCl

~50 g/l NaCl

Up to 60 g/l NaCl

Up to 80 - 100 g/l NaCl

Source: [186, Ullmann's, 2000], [11, US EPA, 1995]


Salt concentration required for reactive dyes

After dyeing, the liquor is drained off and the material is rinsed and then washed off with the

addition of auxiliaries.

In pad dyeing processes dye and alkali can be added together to the dye liquor or in separate

steps into two separate padders (or other types of application systems). When all the

chemicals are applied in one step, the stability of the pad liquor is important. In fact with

increasing reactivity of the dye there is a risk that the dye, after a long dwell time in the pad

box, is hydrolysed by the alkali, before reacting with the fibre. For this reason dye and alkali

are commonly metered separately into the padder. In addition, pad boxes are now constructed

so that the liquor volume is as low as possible, so that it is replaced on average within 5

minutes [186, Ullmann's, 2000].

Among semi-continuous processes the cold pad-batch is by far the most important one for

reactive dyes. After the textile has been padded with dye and alkali, it is rolled up into

batches. Fixing takes place during storage.

In continuous processes, padding, fixing, washing-off and drying are carried out in the same

process line. Fixation is commonly achieved either by dry-heating or by steaming. The

following processes are commonly used:

· pad-steam processes (one common method is the pad-dry-pad-steam process which includes

dye application by padding - intermediate drying - alkali application by padding - dye

fixation with saturated steam - washing - drying)

· pad-dry thermofix processes (dye and alkali are padded at the same time; then the material

can be dried and fixed in a single step or it can be thermofixed after an intermediate drying

stage).

In all cases, after fixation the material is always carefully washed off in open width or in a

rope washing machine to remove completely the hydrolysed colourant and is then dried.

In pad-dry thermofix processes, urea is usually added to the padding liquor to act as a solvent

for the dye during fixation. Urea melts at 115°C and binds water above 100 °C. It can

therefore be used as solvent for the dye in dry heat. A recently developed dyeing process is

now available that does not require the addition of urea.

Urea is also sometimes used in pad-batch processes as dyeing solvent to increase the

solubility of the dye. As early as 1992 the use of urea as dyeing solvent was already in

decline [61, L. Bettens, 1999]. New highly soluble reactive dyes have been introduced in the

market which do not need urea even for deep dyeing in highly concentrated dye liquor.

-N= N-

-NH2NaO S-3

-NaHCO-

OH

Direct red 14 (-N= N-) = Azo group


Direct dyes

Direct dyes are also quite important in cellulose fibres dyeing: 75 % of the total consumption

of these colourants is used, in fact, to dye cotton or viscose substrates Direct dyes are applied

directly from the dye bath together with salt (sodium chloride or sodium sulphate) and

auxiliary agents, which ensure a thorough wetting and dispersing effect. Mixtures of non-

ionic and anionic surfactants are used for this purpose.

In the batch process the dye is made into paste, then dissolved in hot water and added to the

dye bath. The electrolyte is then added to the dye bath. After the dye bath has been drained,

the fabric is washed with cold water and generally subjected to after-treatment.

Pad processes encompass the following techniques:

· pad-steam

· pad-roll

· cold pad-batch

· pad-jig process (the material is padded with the dye and then passed through a salt liquor in

a jigger).

In all processes the material is rinsed at the end with cold water.

With increasing depth of colour the wet fastness can decrease to such an extent that after-

treatment must generally be carried out [186, Ullmann's, 2000]. Two methods exist:

1. removing the unfixed dye by washing with complexing agents or surfactants with a

dispersing effect

2. reducing the solubility of the dye by blocking the hydrophilic groups («enlargement of the

molecule»).

Various techniques can be applied to achieve this enlargement of the molecule. Namely, the

dyed textile can be treated with:

· fixative cationic agents: these are complex substances that form with the anionic dye a salt-

like compound less soluble than the original dye. Quaternary ammonium compounds with


long hydrocarbon chains, polyamines and polyethyleneimine derivatives can be used for this

purpose

· metal salts: copper sulphate and potassium dichromate can form with certain azo dyes

metal-complex with higher light fastness

· agents based on formaldehyde condensation products with amines, polynuclear aromatic

phenols, cyanamide or dicyandiamide (the use of these condensation products leads to the

formation of sparingly soluble adducts with the dye molecules)

· diazotised bases: after dyeing, the material is submitted to diazotisation and is then coupled

with aromatic amines or phenols that must not contain hydrosolubilising groups [186,

Ullmann's, 2000].

Environmental concerns arise when after-treating with formaldehyde condensation products

or metal salts. The method using fixative cationic agents is, therefore, the most frequently

applied. However, quaternary ammonium compounds are often non-biodegradable, fish-toxic

and contain nitrogen.


Light fast direct dyes.

• 1. YELLOW 4RL 200% YELLOW 106

• 1. YELLOW NRL 150% YELLOW 86

• 2. ORANGE 7GL 143% ORANGE 34

• 2. ORANGE 7GL conc ORANGE 46

• 2. ORANGE GGL 143% ORANGE 39

• 3. SCARLET BNL 200% RED 89

• d. BORDEAUX BL 150% RED 99

• d. RED 3B 200% RED 80

• d. RED 6BL 167% RED 79

• d. RED MB 100% RED 243

• d. RUBIS 3BLN 200% RED -

• d. RUBIS KC-BL RED 83.1

• e. BROWN 3R 133% RED 111

• e. BROWN BL BROWN 103

• e. BROWN BRK BROWN -

• f. BLUE 2RL 200% BLUE 80

• f. BLUE 4GL 300% BLUE 78

• f. BLUE 7GL 330% BLUE 218

• f. BLUE BRR 182% BLUE 71

• f. BLUE FGL 200% BLUE 85

• f. BLUE NGL 200% BLUE 200

• g. NAVY BRN 230% BLUE -

• g. NAVY KC-B2R 300% BLUE 222

• h. TURQ. BLUE FBL 330%

BLUE 199

• i. GREEN BL 100% GREEN 26

• j. GREY 4GLN 200% BLACK 62

• j. GREY BGL 167% BLACK 112

• j. GREY KC-LR 165% BLACK 117

• k. VIOLET 5 BL 250% VIOLET 66

• k. VIOLET RL VIOLET 47

• l. VISCOSE BLACK G 250% BLACK 19

• l. BLACK ABV 500% BLACK 22

C

O

C

O

Anthraquinoid Sulphurised

NH

C

O

Indegoid

CO

S

O


Vat dyes

Vat dyes have excellent fastness properties when properly selected and are often used for

fabrics that will be subjected to severe washing and bleaching conditions (towelling,

industrial and military uniforms, etc.).

Vat dyes are normally insoluble in water, but they become water-soluble and substantive for

the fibre after reduction in alkaline conditions (vatting). They are then converted again to the

original insoluble form by oxidation and in this way they remain fixed into the fibre.

When applying vat dyes in batch processes the textile is dyed very rapidly and unevenly due

to the high affinity of the dye. Nevertheless, level dyeing can be achieved by:

· adding levelling agents

· increase of the temperature under a controlled profile ("High Temperature" process and

"Semi-pigmention" method)

· impregnation of the textile with the dye as water-insoluble dispersion, followed by addition

of the reductive agent in a subsequent step (pre-pigmentation process).

In all cases, oxidation and after-treatment follow. After-treatment consists in washing the

material in a weakly alkaline bath with a detergent at boiling temperature.

Continuous processes are used almost exclusively for dyeing woven fabrics and to only a

small extent for knitwear. The most commonly applied continuous process is the pad-steam

process. The textile is padded with the aqueous dye dispersion in the presence of anti-migrant

(polyacrylates, alginates, etc.) and dispersing/wetting agents, if required. After drying, the

fabric is passed through a chemical padder, which contains the required amount of alkali and

reducing agent and is fed immediately to a steamer. The material is finally rinsed, oxidised

and soaped in an open-width washing machine.

A more rapid, one-step process is also possible ,but only for pastel to pale shades.

Voluminous open fabrics can be dyed according to a wet-steam process. Unlike the pad-

steam process, this process does not require intermediate drying before steaming.


The following chemicals and auxiliaries are applied in vat dyeing:

· reducing agents: mainly sodium dithionite (hydrosulphite) and sulphoxylic acid derivatives

(Zn-sulphoxylate). The latter, in particular, is used when the pad-steam process is applied.

Sulphur-free organic reducing agents such as hydroxyacetone are also now available for

some applications

· oxidising agents, such as hydrogen peroxide, perborate, or 3-nitrobenzenesulphonic acid

· alkali (caustic soda)

· salt

· dispersing agents: they are already present in the dye formulation and are further added in

the subsequent steps of the dyeing process

· levelling agents: they form adducts with the dye, thus retarding its absorption onto the fibre.


Vat dyes.

• 1. YELLOW 3GLS YELLOW 33

• 1. YELLOW 3RT ORANGE 11

• 1. YELLOW GCN YELLOW 2

• 1. GOLDEN YELLOW RK ORANGE 1

• 2. BRILL. ORANGE GR gran ORANGE 7

• 2. GOLDEN ORANGE 3GN 80% ORANGE -

• 2. ORANGE RR-N ORANGE 13

• 2. ORANGE RRTS ORANGE 2

• 3. BRILL. RED GGN RED 32

• 3. RED F3B SD RED 31

• 3. RED FBB SD RED 10

• 3. ROSE R RED 1

• 3. RUBIS RB 150% gran RED 13

• 3. SCARLET GG RED 14

• 4. BRILL. VIOLET 3B VIOLET 9

• 4. BRILL. VIOLET RR VIOLET 1

• 5. BLUE BC BLUE 6

• 5. BLUE RS-N BLUE 4

• 5. BRILL. BLUE 3GN BLUE 12:1

• 5. BRILL. BLUE RCL BLUE 6:1

• 5. NAVY AR-N gran BLUE 18

• 5. NAVY BLUE BOA BLUE 20

• 5. NAVY DB BLUE -

• 6. BROWN BR BROWN 1

• 6. BROWN G BROWN -

• 6. BROWN GG BROWN -

• 6. BROWN R-KN BROWN -

• 6. BROWN RN BROWN 3

• 7. BRILL. GREEN FFBN GREEN 1

• 7. BRILL. GREEN GG GREEN 2

• 7. OLIVE GREEN B 150% gran. GREEN 3

• 7. OLIVE MWN GREEN 13

• 7. OLIVE R BLACK 27

• 7. OLIVE T 150% gran BLACK 25

• 8. GREY CL-N BLACK 57

• 8. GREY MG BLACK 8:1

• 8. GREY RBF BLACK 65

• 9. DIRECT BLACK 1188 BLACK -

• 9. DIRECT BLACK R-BN BLACK 9

• 9. DIRECT BLACK RN BLACK -

• 9. BLACK AF gran. BLACK -


Sulphur dyes

Sulphur dyes are used in piece dyeing (cellulose and cellulose-polyester blends), yarn dyeing

(sewing thread, warp yarn for denim fabric, yarn for coloured woven goods), dyeing of flock,

card sliver (wool-man-made fibres blends) [186, Ullmann's, 2000].

Like vat dyes, sulphur dyes are insoluble in water, and, under alkaline conditions, are

converted into the leuco-form, which is water-soluble and has a high affinity for the fibre.

After adsorption into the fibre the colourant is oxidised and converted to the original

insoluble state. The reducing agent, salts, alkali and unfixed dye are finally removed from the

fibre by rinsing and washing.

Mostly continuous dyeing methods are applied, although batch dyeing (in jigger, jet, and

winch beck) is also possible.

In continuous processes the material is impregnated with dye, reducing agent and wetting

agent through a one-bath or a two-bath procedure. With the one-bath procedure (pad-steam

process) the reducing agent and the dye are added at the same time. With the two-bath

procedure (pad-dry/pad-steam) the material is padded in the liquor containing the dye and the

wetting agent, while the reducing agent is applied, if necessary, in a second step, after

intermediate drying. The material is then submitted to air-free steaming. After that, rinsing,

oxidation and re-rinsing are carried out.

Because the exhaustion is not too high, it is possible to re-use dyeing baths in continuous

processes.

Chemicals and auxiliaries applied to the substrate during the dyeing process are:

· reducing agents: sodium sulphide, sodium hydrogensulphide and thiourea dioxide are the

most commonly employed (although their use has decreased over the past decade [281,

Belgium, 2002]). Binary systems made of glucose and sodium dithionite, hydroxyacetone

and glucose or formamidine sulphinic acid and glucose are also used as alternative reducing

agents .

· alkali (caustic soda)

· salt

· dispersing agents (they are necessary in the process steps in which the pigment has not yet

been reduced or has been re-formed by oxidation)

· complexing agents: EDTA or polyphosphates are used in some cases, especially in

circulating-liquor dyeing to avoid the negative effects of alkaline-earth ions on dyeing


· oxidising agents: mainly hydrogen peroxide and halogen-containing compounds such as

bromate, iodate and chlorite.

Azoic dyes (naphthol dyes)

Naphthol AS dyes allow colours with outstanding fastness, but their popularity has declined

because of application costs and the complexity of the process for the preparation of the

colourant [77, EURATEX, 2000].

Dyeing with azoic colourants is a complex process which involves a number of delicate

steps:

· preparation of the naphtholate solution by the hot solution process (the naphthol is dissolved

by boiling with caustic soda) or by the cold solution process (the naphthol is solubilised with

alcohol or cellosolve, caustic soda and cold water). For certain naphthols the addition of

formaldehyde is also necessary to prevent the formation of free naphthol

· application of the naphtholate to the fibre by batch or padding techniques

· preparation of the diazotized base by reaction with sodium nitrite and hydrochloric acid

(this step can be avoided when using fast colour salts)

· formation of the azoic dye into the fibre, by passing the textile, previously impregnated with

the naphtholate solution, through a bath containing the diazotized base or the fast colour salt

(addition of buffering agents is necessary to control the pH, in order to increase the coupling

capacity)

· after-treatment by rinsing the material to remove the excess naphthol from the fibre.


Synthetic fibres dyeing

Polyamide fibres

Polyamide fibres (PA 6 and PA 6,6) are easily dyed with various types of dyes. Due to their

hydrophobic characteristics, they can be dyed with disperse dyes (non-ionic), whereas thanks

to the presence of the groups NH-CO- and NH2- in the polymer chain, acid, basic, reactive

and 1:2 metal-complex dyes (ionic) can also be used. However, in practice acid levelling

dyes are increasingly used.

Before dyeing, fabrics must generally be pre-fixed to compensate for material-related

differences in affinity and to reduce the sensitivity to creasing during the dyeing process. Pre-

fixing can be performed in a stenter frame.

Disperse dyes

Disperse dyes used for polyamide fibres are mainly azo compounds and anthraquinones.

They are applied especially for lighter shades.

The material is dyed in acidic conditions (pH 5) by acetic acid. A dispersing agent is always

added to the liquor.

Acid dyes

As with acid dyeing of wool, with increasing dye affinity, the hydrophobic interaction in the

initial phase must be repressed to achieve uniform absorption. This means that for high-

affinity dyes the liquor must be sufficiently alkaline at the start and then slowly decreased to

optimise exhaustion. The level of acidity of the liquor is regulated either by dosing with acids

during dyeing or by adding acid-donors (e.g. ammonium sulphate, sodium pyrophosphate or

esters of organic acids) at the start of the process .Optimal exhaustion and uniform dyeing

can also be achieved by controlling the temperature profile.

Auxiliary agents (anionic, cationic, non-ionic surfactants) are normally used to improve the

levelling effect.

The wet-fastness of dyeing with acid dyes on polyamide fibres is often unsatisfactory. After-

treatment with syntans (synthetic tanning agents) is often necessary. The syntans are added to

the exhausted bath or to fresh liquor at pH 4.5 by formic or acetic acid. The material is

treated at 70 - 80 °C and is then rinsed.


Metal-complex dyes

Among 1:2 metal-complex dyes, molecules containing sulphonic groups are the most suitable

for polyamide fibres.

The absorption of the dye increases with decreasing pH. Dyeing conditions vary from weakly

acidic by addition of ammonium sulphate and acetic acid to neutral or moderately alkaline

for high-affinity dyes. For high-affinity dyes amphoteric or non-ionic levelling agents are

usually added.

Reactive

In principle, the reactive dyes used for wool are also suitable for polyamide. The dyeing

process is carried out in weakly acidic conditions (pH 4.5 - 5). The process is started at 20 -

45 °C and then temperature is increased near to boiling. Non-ionic surfactants and sodium

bicarbonate or ammonia are used in the after-treatment step.

Dyestuff Chemicals and auxiliaries/ typical application conditions Technique

Disperse - PH 5 by acetic acid

- dispersing agents (sulphoaromatic condensation products or

non-ionic surfactants)

- dyeing is conducted at near-boiling temperature

Batch

Acid dyes - pH conditions from acid to neutral depending on the affinity of

the dye

- optimal bath exhaustion and level dyeing are achieved by

either pH or temperature control methods (levelling agents are

also used)

- in the acidic range, electrolytes retard the exhaustion

- with levelling dyes, wet-fastness is often unsatisfactory and

after-treatment with synthanes can be necessary

Batch

1:2 metal-

complex dyes

- dyes containing sulphonic groups are preferred because they

are more water-soluble and produce better wet-fastness

- to improve absorption of low-affinity dyes (especially for

disulphonic) dyeing is carried out in weakly acidic conditions

using acetic acid

- high-affinity dyes are applied in neutral or weakly alkaline

medium using amphoteric or non-ionic levelling agents

Batch

Reactive dyes - in principle the reactive dyes used for wool are also suitable for

PA

- dyeing is conducted at near-boiling temperature in weakly

acidic conditions

Batch

- after-treatment is performed at 95 °C using a non-ionic

surfactant and sodium bicarbonate or ammonia


Polyester fibres

Articles made of pure PES are dyed almost exclusively using batch dyeing techniques and

among these, dyeing under high-temperature conditions is the most commonly applied.

Dyeing polyester fibres under atmospheric conditions (below 100 °C) was also frequently

done in the past with the aid of carriers. Since these substances are ecologically harmful,

dyeing below 100 °C is no longer in use today for pure PES fibres, unless carrier-free

dyeable fibres are employed.

Concerning high-temperature dyeing, the process is usually carried out in acidic conditions

(pH 4 - 5) with addition of acetic acid under pressure at 125 - 135 °C. In these conditions

levelling agents are necessary to prevent excessively rapid absorption.

Provided that alkali-stable dyes are used, dyeing in alkaline medium (pH 9 - 9.5) is also

possible. This technique has been developed in order to counteract the migration and

deposition of oligomers typical of PES fibres.In fact, oligomeric components (cyclic trimers

of ethylene terephthalate are especially harmful) tend to migrate out of the fibre during

dyeing, thus forming with the dye agglomerates that can deposit on the textile or on the

dyeing equipment. To achieve level effects, ethoxylated products are used as levelling

agents.

The thermosol process is another applied technique, although it is primarily used for

PES/cellulose blends. The dye is padded on the textile together with an anti-migration agent.

A drying step at 100 - 140 °C is carried out. Then the dye is fixed (200 - 225 °C for 12 -

25 seconds).

For light shades, the material needs only to be rinsed or soaped after dyeing. For dark shades,

in order to ensure high light fastness, an after-clearing step is normally necessary. This

usually consists of an alkaline reductive treatment followed by post-rinsing in weakly acidic

conditions.

PES fibres can be dyed with cationic dyestuffs, provided that acidic components (e.g.

sulphated aromatic polycarboxylic acid) are used as co-monomers during the manufacturing

of the fibre (creation of anionic sites).


Dyestuff Chemicals and auxiliaries/ typical application

conditions

Technique

- pH 4 - 5 by acetic acid

- levelling agents (aliphatic carboxylic esters, ethoxylated

products, combinations of alcohols, esters or ketones

with emulsifying agents)

- possible addition of complexing agents (EDTA) for

dyes sensitive to heavy metals

Batch dyeing at 125 -

135 °C under pressure

(HT)

- this techniques requires the use of carriers unless

modified polyester fibres are employed

Batch dyeing below

100 °C

Disperse

- pH 4 - 5 by acetic acid

- thickeners such as polyacrylates and alginates are added

to the padding liquor in order to prevent migration of the

dye during drying

- after-treatment with a solution containing sodium

hydrosulphite and sodium hydroxide (dispersing agents

are added to the last washing bath)

Thermosol process

Acrylic fibres

So called PAC fibres are hydrophobic and contain anionic groups in the molecule. As a

result, they can be dyed with disperse and cationic dyes. With the introduction of cationic co-

monomers in the polymer, the fibre can also be dyed with acid dyes.

Batch dyeing is commonly applied for cable or stock (package dyeing), yarn in hank form or

packages and for fabric. Piece dyeing can be performed on beam, overflow, paddle (for

knitwear, ready-made bath sets), or drum (socks).

Stock, cable and top can be also dyed on special machine, using the pad-steam process,

preferably with pressurised steam to obtain short fixing times. Piece goods, especially

upholstery material (velour), are also dyed according to the pad-steam process, but in this

case fixing is carried out with saturated steam. This implies longer fixing times, which means

that rapidly diffusing cationic dyes and dye solvents are required.

Disperse dyes

Disperse dyes are used to produce light to medium-deep shades. The dyeing techniques

correspond to those used on polyester fibres. However, dyeing can be performed at

temperatures <100 °C without carriers. Furthermore, due to the good migration properties of

disperse dyes, levelling agents are not required.


Cationic dyes

Typical recipes used in batch dyeing include an electrolyte (sodium acetate or sodium

sulphate), acetic acid, a non-ionic dispersant and a retarding agent. Dyeing is conducted by

controlling the temperature in the optimum range for the treated fibre. Finally the bath is

cooled down and the material is rinsed and submitted to after-treatment.

Continuous processes commonly applied are:

· pad-steam process (fixation with pressurised steam at more than 100 °C) - this process has

the advantage of reducing fixing time. Pad liquor typically contains a steam-resistant cationic

dye, acetic acid and a dye solvent

· pad-steam process (fixation with saturated steam at 100 - 102 °C) - this process requires a

longer fixing time. Rapidly diffusing cationic dyes and dye solvents, which exhibit a carrier

effect, are required.

When dyeing with basic dyes, special levelling agents (also called retarding agents) are

widely used to control the absorption rate of the colourant on the fibre, thus improving level

dyeing.

Dyestuff Chemicals and auxiliaries/ typical application

conditions

Technique

Disperse - dyeing conditions correspond to those used for

polyester

- addition of carriers is not required

- Acetic acid (pH 3.6 - 4.5)

- Salt (sodium sulphate or sodium acetate)

- Retardant auxiliaries (usually cationic agents)

- Non-ionic dispersing agents

Batch

- Acetic acid (pH 4.5)

- Dye solvent

- Steam-resistant, readily-soluble dyes (usually

liquid) are required

Pad-steam process with

pressurised steam

Cationic

- Dye solvent Pad-steam process with

- Rapidly diffusing dyes are required saturated steam

Summary of the most common dyestuffs and dyeing techniques for polyacrylic fibres

Cellulose acetate (CA) and cellulose triacetate (CT)


In contrast to the other regenerated cellulose fibres, CA and CT are hydrophobic and

therefore they can be dyed with disperse dyes under conditions which are very similar to

those applying to PES fibres.

Cellulose acetate is dyed by the exhaustion method with disperse dyes in the presence of

non-ionic or anionic dispersing agents in weakly acidic conditions (pH 5 - 6). Dyeing is

normally done at 80 - 85 °C. However, a series of less wetfast dyes already absorb onto the

fibre at 50 - 60 °C, whereas more wetfast dyes require temperatures up to 90 °C.

Compared to CA, CT dyeing and finishing characteristics are more similar to purely

synthetic fibres. CT, like CA, is dyed with disperse dyes in a weakly acidic medium in the

presence of levelling auxiliaries. Applied dyeing techniques for CT are:

· batch dyeing process, usually at 120 °C, but if these conditions are not possible a dyeing

accelerant (based on butyl benzoate or butyl salicylate) is required

· thermosol process.

Fibre blends dyeing

Natural/synthetic fibre blends are becoming more and more important in the textile industry

because this allows combining the favourable technological properties of synthetic fibres

with the pleasant feel of natural fibres.

Of the worldwide consumption of PES fibres, 55 - 60 % is used in blends with cellulose

fibres or wool. About 40 % of polyamide is used in blends, while 50 % of polyacrylic fibres

is used especially in blends with wool for knitwear [186, Ullmann's, 2000].

Fibre blends can be produced according to three different methods:

· fibres of different types in the form of staple fibres are mixed at the yarn manufacturing

stage, during spinning

· fibres of different types are separately spun and the resulting yarns are wound together to

give a mixed yarn

· fibres of different types are separately spun and combined together only at the weaving

stage where one or more fibre yarns are used as warp and the other ones as weft.

Dyeing of blend fibres is always longer and more difficult as an operation compared to pure

fibre dyeing. Despite these disadvantages, dyeing tends to be placed as close as possible

towards the end of the finishing process. In fact this enables the dyer to satisfy the requests of

the market without the need to store large amounts of material already dyed in flock or yarn

form in all available shades.


When dyeing blend fibres, the following methods can be applied:

· the two fibres are dyed in the same tone ("tone on tone") or in two different shades using the

same dyes

· only one fibre is dyed (the colourant is not absorbed by the other ones)

· the different fibres are dyed in different tones.

For "tone on tone" dyeing, it is sometimes possible to use the same dye for the different

fibres. When dyes of different classes have to be employed, the dyeing process is easier to

control when the selected colourants have affinity only for one fibre and not for the other

one. In reality, however, this situation is exceptional and the dyeing of fibre blends remains a

complex operation.

Blend fibres dyeing can be done in batch, semi-continuous and continuous processes. Batch

processes include:

· dyeing in one bath and one step (all dyes are added in the same bath in one single step)

· dyeing in one bath and in two steps (dyes are added to the same bath in subsequent steps)

· dyeing in two baths (dyes are applied in two steps in two different baths).

The most common fibre blends will be discussed in the following sections.

Polyester-cellulose blends

A large part of the entire production of PES (ca. 45 %) is used to make this mixture.

Polyester-cellulose blends are used for all types of clothing and for bed linen. The cellulose

component is usually cotton, but viscose staple fibres and occasionally linen are also used.

The preferred mixing ratio is 67:33 PES: cellulose (for textiles worn close to the skin), 50:50

and 20:80 [186, Ullmann's, 2000].

In dyeing PES-cellulose mixtures, disperse dyes are used for the polyester component, while

the cellulose portion is usually dyed with reactive, vat and direct dyes. Pigment dyeing is also

commonly used for light shades.

Disperse dyes stain cellulose fibres only slightly and they can easily be removed by

subsequent washing or, if necessary, by reductive aftertreatment. Most of the dyes used for

cellulose stain PES only slightly or not at all.


PES-cellulose blends are commonly dyed in continuous processes. Nevertheless, for yarn and

knitwear, batch dyeing is of major importance.

In batch dyeing, the application of dyes can be done in one or two steps in one bath or in two

different baths in subsequent stages. The disperse dye is generally applied at high-

temperature (HT) conditions without the use of carriers.

In the one-bath/ one-step procedure, special auxiliaries, so-called acid donors, are used,

which lower the pH when the temperature is increased. In this way, it is possible to fix the

reactive dyes in alkaline conditions and then reach the optimal dyeing conditions (pH 5 - 6)

for disperse dyes by increasing the temperature. Alternatively, it is advantageous to operate

at pH 8 - 10 using alkali-stable disperse dyestuffs, which also avoid oligomer problems.

The one-bath/ one-step procedures are preferred, being more economic, but present more

difficulties. For example, the presence of salt increases the tendency of disperse dyes to stain

the cotton fibre of the blend. Recently developed low-salt reactive dyes are claimed to show

good performance and high reproducibility in this application.

In continuous processes the dyes are usually applied in one bath. The fabric is subsequently

dried and disperse dye is fixed to the PES component by the thermosol process. Afterwards,

the second dye is developed according to the procedure typical of each class, using in general

pad-steam, pad-jig or pad-batch processes. Dyes are applied according to application

conditions typical of their class. For more details regarding a given class of colourant, see the

specific section.


Technique Disperse/vat Disperse/reactive Disperse/direct Pigment

One-bath process Y K W (1)

Two-bath process Y K

Batch

One-bath two-step

process

Y K Y K Y K

I stage II stage

Thermosol

+ pad-jig

W

Thermosol

+ pad-

batch

W

Continuous

Application

of all dyes

in one

bath by

padding +

drying

followed

by:

Thermosol

+pad-

steam

W W W

Y = yarn

W = woven fabric

K = knitted fabric

(1) Pigment dyeing includes padding with the pigment, a binder and auxiliaries, drying and

polymerisation at 140 °C for 5 min.

Polyester-wool blends

Polyester-wool blends are widely used, especially for woven goods and knitwear. The most

frequently found ratio is 55:45 PES: wool.

Wool cannot be dyed at the high temperatures typical of the HT dyeing process for PES

fibres and PES-cellulose blends. The dyeing time should also be as short as possible so that

the wool is not damaged. For large productions it is therefore preferable to dye wool and PES

separately in top, blending the two fibres at the yarn manufacturing stage. However, quick

changes in fashion and short-term planning frequently do not allow separate dyeing.

When dyeing polyester-wool blends, disperse dyes are used for polyester and anionic (acid

and metal-complex dyes) for wool.

Only disperse dyes that stain wool as slightly as possible or are easily removed by washing

can be used for dyeing wool-polyester blends. Disperse dyes, in fact, tend to stain wool and a

reductive after-treatment is not always possible (appropriately stable dyes are required).


PES-wool blends are typically dyed according to the following batch processes:

· at boiling temperature with carriers

· at 103 - 106 °C with little carrier

· at 110 - 120 °C with the addition of formaldehyde as a wool protective agent and with low

amounts of carriers or none at all (HT conditions).

The one-bath process method is preferred in practice; the two-bath process is applied when

deep shades and high fastness are required. The material is first dyed with disperse dyes. A

reductive intermediate treatment may be applied before dyeing the wool part. In both dyeing

methods, after dyeing, an after-treatment is applied to remove any disperse dye attached to

the wool, if the dye used for wool can withstand it. The material is treated with ethoxylated

fatty amine in weakly acid liquor at 60 °C.

Polyamide-cellulose blends

Since PA fibres have an affinity for almost all dyes used for cellulose, different possibilities

are available for dyeing this blend:

· direct and disperse dyes (pH 8)

· acid or 1:2 metal-complex dyes (pH 5 - 8)

· vat dyes (exhaust and pad-steam process are used)

· reactive dyes.

Application conditions are those typical of each class of dye. They have already been

described in the specific sections.

Polyamide-wool blends

Blends with polyamide/ wool ratios varying from 20:80 to 60:40 are used. This blend is

particularly important in the carpet sector. More detailed information is therefore reported in

the specific section dedicated to this sector (see Section 2.14.5).

As general information about the dyeing processes suitable for this type of blend, both fibres

have affinity for acid and 1:2 metal-complex dyes. However, since PA is more accessible to

the dye than wool, it is dyed more deeply, particularly in the case of light colours. To

counteract this effect, special levelling agents (also called PA reserving/ blocking agents) are

used (mainly aromatic sulphonates). These auxiliaries have a relatively high affinity for the

PA fibre and retard the absorption of the colourant on this part of the blend.

Dyeing is performed in the presence of acetic acid and sodium sulphate. Due to limited

fastness of acid dyes, 1:2 metal-complex dyes are required for dark shades [186, Ullmann's,

2000].


Acrylic-cellulose blends

PAC-cellulose blends are used for household textiles (drapery and table linen) and imitation

fur ("peluche", in which the pile consists of PAC fibres and the back is made of cotton). The

percentage of PAC in the mixtures varies between 30 and 80 %.

PAC can be dyed with cationic or disperse dyes, while direct, vat or reactive dyes can be

used for the cellulose component.

The following methods are the most commonly used for dyeing this blend:

· continuous dyeing with cationic and direct dyes according to the pad-steam process (to

avoid precipitation of cationic and anionic dyes present in the pad liquor at relatively high

concentration, combination of anionic and non-ionic surfactants are added to the solution)

· batch dyeing (usually according to the one-bath, two-steps method) with cationic and vat

dyes or with cationic and reactive dyes.

Acrylic-wool blends

Among synthetic fibres, PAC fibres are the most suitable for obtaining blends with wool that

keep a wool-like character. This makes this blend widely used, especially for knitwear and

household textiles. The blending ratio of PAC to wool varies from 20:80 to 80:20.

Metal-complex, acid and reactive dyes are the dyestuffs typically used for the wool part,

while PAC is dyed with cationic dyes.

Cationic dyes stain wool fibre. As a matter of fact cationic dyes attach first to wool and then

migrate to PAC fibre at higher temperature. Even if well-reserving dyes are selected, dyeing

must be conducted for a sufficiently long time (from 60 to 90 minutes) in order to obtain

good wool reserve [186, Ullmann's, 2000].

PAC-wool blends can be dyed using the following exhaustion methods:

· one-bath one-step

· one-bath two-step

· two-bath.

The first one allows shorter dyeing times and lower consumption of water. However, it is not

always applicable because the simultaneous presence in the dye bath of anionic and cationic


compounds can produce the precipitation of the formed adducts on the fibre. Precipitation

can be prevented using dispersing agents and selecting adequate dyes.

When dyeing with the one-bath, two-step method the use of reserve agents is not necessary.

In fact, wool absorbs the cationic dye and slowly releases it, acting as a retarding agent

(exerting a retardant effect on PAC).


Physical problems in continous dyeing

PROBLEMS IN DYEING

1. General Problems / Non Technical Problems

2. Process Dependent / Technical Problems

1-General Problems / Non Technical Problems: -

These problems occur due to wring

calculation, wrong recipe, not good stirring, tint and water marks etc.

Stains: -

o Due to aggregation

o Due to dirty machine

o Chemical and dye solution aggregation.

o Improper dye dissolution

o Non uniform dispersion

Tint: -

Tint occur due to dirty machine

2-Process Dependent / Technical Problems

CONTINUOUS METHOD: -

LISTING: -

This is (L.C.R) left centre right problem. Shade different from left to

right reason may be migration, uneven squeezing.

BACK FACE: -

I. Mechanical Problem: -

o I.R pre-drying not well

o Pick up should be 65%

o Should be control air circulation


II. Chemical Problem: -

o Antimigrating agents

o Thickners

TAILING: -

This is major problem shade difference from start to end.

I. Tone Tailing: -

When fabric run on a machine after some meters there is a

tone difference from start and after some running. Reason is

affinity difference.

II Depth Tailing: -

This is a depth (light or dark) shade variation is a fabric.

Affinity Dyes

Depth Tailing

Non-affinity Dyes Reactive dyes are affinity dyes and vat dyes are non-affinity dyes.

NOTR: -

Yellow more affinity then blue, yellow rush to fabric. There is more yellow

% age in solution. To avoid this same class of dye like Ramazol is use.

PENETRATION PROBLEM: -

For good penetration Moisture Content, pressure,

temperature, time should be same. If penetration is

good washing, rubbing and light fastness is good.

Normally (40 – 60 sec) 105Co is required. It is

controlled in steamer.

FIXATION FAILURE: -

o Not required chemical concentration if we get.

o Not proper temperature


o Not proper pressure

UN – EVEN DYEING: -

o Shade variation occurs if dry chamber temperature is not well.

o Speed variation

o Error of dye weight

o Not proper colour mixing

o Wrong chemical formulation

o Temperature of chemical solution not maintained

o If washing is not done with proper soap concentration

In continous dyeing there are so many chemical and physical problems occurs during

continous dyeing. Continous dyeing is divided into following parts .Some of physical

problems are given in details in the following,

1. Padding process

2. the drying process

3. fixation process

4. washing process for unfixed dye particles

1-Padding process

In this process the fabric is passed from padder after passing through trough containing dyes

and chemicals. There are four rollers in the trough. There is one pair of squeezing roller.

Padder is shown as,

Vertical padder for lab

Following are the problems that occur in this process,


A-Condition of fabric to be dried

• Evenly dried fabric;uniform moisture over the length and width of the fabric .

• Uniformly cooled to room temperature to prevent increasing temperature in

padding solution.

• Pretreatments should be applied uniformly as singeing,desizing, scouring,

bleaching and mercerization.

• The fabric to be dyed should be free of creases , other wise the padding will

be un even.

• Adequate relaxation of fabric to be dyed in padding.

The padding mangles are shown in the following fig.

Vertical padder horizontal padder

B-Notes for padding equipments and operation:

• In continous dyeing of woven textiles, the two nip and dip of padding has

practically no effect on improvement of penetration.

• The rubber squeeze rollers should be adjusted to the proper pick-up for

uniform pressure from side to side and side to center . in short it is called L-C-

R (left-center-right).

• The pick-up should be determined by the diameter and hardness of rubber

rollers . Although the pick-up depends on the type and construction of the

fabric.

For polyester/cotton blended fabrics 50-65%

For polyester/rayon blended fabrics 55-70%

• Since the rollers are designed so that they exert uniform pressure on the

whole width of the fabric because this pressure usually vary from edges to

center. The special designed rollers are slightly different in diameter which

is technically called as crowning.


2-Drying process

The padded fabric should be immediately applied “drying” to satisfy the next fixation

treatment of the padded fabric.

Since dye stuffs have not yet fixed with the fibres in this process , the migration phenomenon

is occurred where by dyes tend to move along side

Moisture evaporating during drying not only from the in side of fabric to the surface but also

from center to the both sides.

Even if dye is applied to the fabric uniformly in a padding

process,migration during drying process is liable to create such problems as unlevelness

listing and poor appearance. It is necessary to formulate padding racipies and drying

conditions that will minimize the migration as much as possible.

Drying machines: There are two drying machines that are used for drying purpose

• Hot flue dryer

• Infrared dryer

Hotflue dryers are generally work on jet system . hot air is fall uniformaly over the fabric

through jet. They are also called drying chambers their digram is shown as follows,

Where as infrared dryers are basically rays that across the fabric from both sides and it is

vary usefull in migration of the dye particles from the core to surface of the fibre. Although

they have no high efficiecy as the movement of the water particles over the fabric surface is

rather slow. The infrared dryers are shown as follows,


So for having high efficiency we use hot flue and infrared dryers

combined .

2- Phenomenon of migration:

Migration is the process by which a dye move around the fibre or level

itself. The migration process comprises adsorbtion of dye onto the fibre

sureface,migration through the dye liquor,re-adsorbtion onto the fibre structure.

Migration itself is also heavily influenced by temperature.

The phenomenon of dye migration on polyester/cellulose blended

fabric is classified into two phenomenon

1- The movement of dye particles to the surface of fibre during drying process.

2- The movement of individual dye molecules into the interior of fibre during

thermosoling process.

Relation b/w drying mechanism after padding of dye solution and phenomenon of

migration of dye molecules to the surface of the fabric is considered as follows.

First the water evaporates from the surface of the fabric by the thermal energy

from heat source and the water content decreases on the surface of the fabric.

The difference of water content b/e the surface of fabric and the interior causes

the water movement from the interior of the fabric to the surface by capillary

action.

The water begins to evaporates when reaching the surface but the dye particles

moving alongwith remain and accumulate on the surface.

Some of the vapors produce near the surface of fabric begin to evaporate as

result of the difference in vapor pressure.the rest of thje vapors move into the

interior of fabric and transmission of heat happens quickly inside of the fabric.

The vapors move into the interior of fabric are recondenced to liquid and move

again to the surface of fabric.

After consistant drying are repeated , the movement of water from the interior

of fabric to the surface eventually ends.

3-Factors affecting migration:

Air speed

In hot air drying, air speed provide the most prominent influence on the rate of

drying and simultaneously influences upon migration.


Temperature :

The temperature of hot air for drying is not so effective on migration as

air speed. In general the affect of temperature difference on migration decreases

considerably at temperatures higher than 100C.

Humidity:

Humidity has no effect on migration practically. On the other hand, the

moisture in the hot air is liable to lower drying efficiency by slowing the drying speed

and simultaneously create a difference in concentration between the surface and the

backside of the dyeings. Consequently dyeing should be carried out under low humidity

as much as possible.

Infra red dryer:

In hot flue drying , the temperature of padded fabric cannot reach

over 50-60C on wet bulb until the water completely evaporates from the padded fabric. In

infra-red drying,on the other hand, the temperature of the padded fabric can be increase

to boiling point. The mterial is swelled and the dye penetration into the structure if the

fibre is improved., more over since the bound water in cellulosic fibre become larger by

increasing temperature. The volume of free water In the fibre decreases and the

migration become smaller. However an exesive radiation of infrared ray will result in

drying under boiling conditions , by which the drying is accelerated and simiultaneously

migration become larger , therefore the proper radiation of infra red ray should be

applied.

The most effective drying method generally follow this sequence , 20-30%

water of pick-up ratio of the padded fabric is generally dried by the radiation of infrared

rays.

Test method:

Two pieces of fabric sewn one over the other are padded with the dye padding

solution , sqeezed ,dried and developed.

The dyeing strength of the out side and inside of above dyeing are measured .

M= (K/S)0__________

[ (K/S)0 +(K/S)1] *1/2

(K/S)0 =dyeing strength of out side

(K/S)1=dyeing strength of inside.


Relation between water contents and migration:

In this stage , free water constantly moves from interior of

fabric to the surface and the dyes migrate to the surface with water on fabric. When the

drying enters into the falling drying-rate period , only the bound water remains inside of

fabric , there for the diffusion of water to the surface decreases.

Relation between pick-up and migration property:

However, if the percentage of pick-up is lowered

too much, the water retained mechanically in the fibre structure may notb diffuse

sufficiently through out the interior of fabric and cause irregular distribution, thus

resulting in poor appearance of dyeing.

Consequently , besides adding migration inhibitor

to the padding solution , it is necessary to determine the optimum condition for pick-up

according to the sort of fibre.

Migration inhibitors: The migration property of dyes is largely influenced by the

type of migration inhibitors and by the amount applied. As common migration inhibitors ,

sodium alginate and synthetic thickening type agents of venyl acetate or acrylic acid types

are used.

Of these migration inhibitors, synthetic thickening type agents

are inferior to sodium alginate in migration inhibiting effects but, on the other hand, they

generally show favorable results in appearance of dyeing because of their better adhesive

effect of dyes on polyester.

Sodium algenate synthetic thickening type agent

Thin fabric 0.4-0.6g/l 5-10g/l

Thick fabric 0.8-1.0g/l 15-20g/l

Particle size of dyes: In case of water insoluble dyes such as disperse dyes and vat

dyes, the degree of migration varies according to the particle size of dye as shown in the

following table,


Size of dye particle migration index(M)

Without thickening agent

Over 2micron 1.47

Ca.1micron 1.71

0.4-0.6micron 1.86

0.1-0.3 micron 1.88

0.03-0.07 micron 1.91

Under o.o3 micron 1.93

Fixation process: The following processes are applied fro fixing disperse dyes on

polyester fibres,

1. Thermosol method

2. High pressure steaming method

3. High temperature (HT)steaming method

Thermosol method This method , applying drying heating to fix disperse dyes on polyester

fibres,is generally used for fixation in continous dyeing of polyester /cellulosic blended

fabric.

High pressure steaming method: This method applies the continous high pressure to fix disperse dyes onto

the polyester fibre.

In comparison with thermosoling method and high temperature steaming method, this

method has advantages of high fixation and less staining on cellulosic fibres , but on the

other hand is liable to show poor reproducibility unless water contents and pH controlled

accurately.

High temperature steaming method: This method , applies super heated steam to fix the disperse dyes on

polyester fibres, is gaining popularity , epecially recently , for fixation of print on polyester

woven fabric.


Continous dyeing of polyester/ cellulosic

fabrics with disperse dyes and vat dyes

Method: pad-developing

For continous dyeing of polyester /cellulosic blends with disperse dyes and vat dyes.two

methods are usually adopted,

One bath method

Two bath method

One bath method

In one bath method , blends is padded through the solution containing

disperse dyes and dispersed type vat dyes,after drying ,disperse dyes are developed on

polyester fibres by thermosolingand vat dyes are developed on cellulosic fibres.

Two bath process:

In two bath method ,disperse dyes are first applied on polyester fibre by

thermosol dyeing and then vat dyes are applied on cellulosic fibres in a separate process.

Procedure of disperse dyes in continous dyeing

There are so many combinations of blended fabrics. Each blended fabric has it’s own

process to dye. Disperse dye is purely used for polyester fabric and vat for cotton. Now we

will study about the process and behavior of these dyes during process.

1. Behaviour of disperse dyes in padding process:

The padding pocess is very important in

continous dyeing . in order to obtain dyed fabrics of superior quality and good

reproduceability , it is necessary to pad dye solution evenly on fabric in padding process. To

meet these requirements there are many perameters that should be taken into account.

• Tailing :

The phenomina called tailing will vary depending upon the kinds of fibres

and substantivity, particle size and dispersibility of dyes.

On the good hydrophilic fibres like cellulosic fibres , water vis primarily

absorbed on fibres. As shown in the curve[1] of fig., the concentration of padding solution

increases as time elapses , and eventually reaches equilibrium at level of concentration about

20% higher than that of original padding solution. In contrast on hydrophobic fibres suchas

CCCContinous dyeingontinous dyeingontinous dyeingontinous dyeing 111109090909

polyester, the hydrophobic dyes is absorbed primarily as shown in curve [2] , the

concentration of padding solution increases as time elapses , and eventually reaches

equilibrium at level of concentration about 20% higher than that of original padding solution

Concentration of padding solution

Pdding time

This behaviour to minimize tailing in blends, though depending upon blending ratio, may be

attributed to the mutual reaction between the hydrophobic of cellulosic fibres, and also to use

of thickening agent with a high degree of hydration as migration inhibitor in practical

padding solution.

• Speck: The formation of speck during padding is largely influenced by particle of size of

dyes, the compatibility of these dyes with migration inhibitors and penetrating agents etc.

though depending upon the structure and density of woven fabric, the dye particle which will

be larger than 3 micron causes formation of specks in case of polyester / cellulosic blended

poplin fabric.

If dye dispersability caused by poor compatibility between dyes and auxilaries

remarkably deteriorates, it leads not only formation of specks on the fabric but also tailing

problem.further more , dispersion solution ar sometimes applied or stored for a longer time

after preparation untill padding finished, and dispersed dyes which stain the wall of pad

trough are dried and then drop back into the padding solution., the redispersibility of dyes is

one of the important factor for the formation of speck on fabric.

• Listing:

The phenomenon called listing refers to differences in color strength and shades

on the dyed fabrics as a result of unlevel dyeing from selvedge to selvedge and from

selvedge to center , the following are points reasoning the listing.

� Uneven drying of fabric prepared from padding from selvedge to center to delvedge.

� Uneven temperature of material.

� Uneven pressure of squeezing.

� Uneven temperature of padding solution.

� Uneven feeding of padding solution.


� Difference in dye migration due to air viscosity.

� Difference of temperature dependency of disperse dyes during their thermosoling.

2-Behaviour of disperse dyes during drying:

Problems during IR drying and ho lfue drying include the

migration of disperse dyes and the influence on the chemical structure of disperse dyes by

oxidation gases.

Concerning migration of dyes , this problem should be

comperetively easy to solve when one dye will be used alone. There for it is important to

select similar dyes inn migration properties in order to avoid listing, shade difference of

between surface and backside of fabric. Regarding the chemical change caused by oxidizing

gases,partially no problem ever occurs when steam or elasticity is applied. In contrast, the

major problem occur when IR dryers or hot flue dryers directly heated with gas is applied.

3-Behaviour of disperse dyes during thermosoling process :

In padding of polyester /cellulosic blended fabric with

disperse dye solution because of difference between hydrophobic and hydrophilic property of

the blend,distribution of disperse dyes tends to be more on cellulosic fibres than on polyester

fibres. To obtain good levelness and appearance of the dyed fabric ,however, disperse dyes

should be distributed as uniformly as possible on both polyester and cellulosic fibre in

padding solution.

In thermosol process , the disperse dye particle on both fibres

are vaporized into molecular form by heating, and ,the molecular movement of polyester

fibre arev simultaneously stimulated by this heat, and then disperse dyes which is meanwhile

vaporized into molecules are dissolved an exausted into amorphous region of polyester , of

which inter molecular linkage was already loosed.

On the other side, disperse dyes on cellulosic fibres also

vaporized and migrate onto polyester fibres,but in this case , the color yield ratio lower than

that of disperse dyes on polyester fibres. Consequently , in thermosol dyeing of polyester

/cellulose blended fabric (65/35) with disperse dyes , a fixation ratio is only 70-80% and rest

of 20-30% either sublimate and diffuse into atmosphere or else remain on the cellulose

fibres are also called staining on cellulose.


Procedure of vat dyes in continous dyeing

The process of vat dye in continous dyeing show the following behaviors during dyeing

process.

1-Behaviour of vat dyes in padding solution:

The behaviour of vat dye is similar to disperse dye . there are

following precautions that should be taken into account,

Precautions during padding

The following precautions are necessary to get uniform padding

with dye solution on blended fabrics.

--dispersibility of dyes and stability of dispersion.

--compatibility of dye dispersion (including compatibility of disperse dyes)

Precaution during drying process:

The most important point to keep mind during drying is to

avoid problems such as listing, color difference from back to face, and poor surface

appearance , caused by dye migration.

2-Behaviour of vat dyes during thermosoling of process

In one bath dyeing of blended fabric ,disperse dyes

are developed by thermosol treatment . in this thermosol process vat dyes are not chemically

influenced , but a certain type of vat dye iss is stained polyester fibre. When the degree of

staining of vat dyes on polyester fibre becomes high,dyeing strength and shade of polyester

fibre portion and light fastness are liable to be influenced.

This property depends upon not only the

chemically constitution of vat dyes but also impurities contained in these dyes. Due to the

difficulty to prevent staining on polyester by vat dyes through using auxiliary and

modification of dyeing procedure . it is necessary to select vat dyes which have the leasty

staining on polyester fibres.

Further more staining on polyester by vat

dyes in themosoling become higher ratio in paler shade. In contrast , the ratio of staining

indeep shdes , does not increase therefore it is necessary to be mind in pale dyeing.

3-Behaviour of vat dyes during in chemical padding process:

The chemical padding process in the proper application

of pcaustic soda and hydro sulphate that rae necessary for reducing dyeing of vat dyes . the


proper amount of then is required depending on kinds of vat dyes and dyeing depth. When

formulation of chemical solution is not properly prepared and /or temperature of it increases.

The vat dyes padded on the fabric are liable to drop and thus lead to such problems as tailing

and high level dyeings.

The temperature of chemical bath should therefore

be kept in around 20C or preferably bellow 15C. Further more , it is possibly dangerous that

temperature of chemical solution in creases by excess steam of if the chemical tank is

mounted too close to the steamer. To avoid this risk ,therefore, the tank should be equipped

with cooling system.

Beside above mentioned controlof temperature of a chemical bath . an other preventive to

avoid bleeding of vay dyes into a chemical bath are (a) an increase of the amount of

migration inhibitors. Vat dyes are padded to minimize migration of dyes to the fabric surface

and (b) not strong nip pressure during chemical padding the pick-up of chemical padding

should be recommended from 15-20% more than the pick-up of padding at any rate. It is

necessary that should be strength chemical solution for developing of vat dyes are padded

and also that appropeiate adjustment of padding solution should be made not to flow out to

surface of fabric during susiquent steaming.

In continous dyeing of polyester/cellulose blends will desperse dyes

and avt dyes.

4-Behaviour of vat dyes during in steaming process:

Immediately after chemical padding the afbtrci is

padded into a steamer and steamed under saturated steam. In the steaming process the vat

dyes immediately form water soluble leuco salt which has strong affinity to cellulosic fibres

and then immediately dye cellulosic fibres.

In case it takes longer time to introduce the fabric into a

steamer of a chemical padding or if air accidently enter into a steamer ,H2S on the fabric is

liable to be consumed much and normal reduction and dyeing of vat dyes cannot be obtained.

In addition in case of super heated steam in a steamer or if pi-up ratio of chemical padding is

lower . the moisture retained in fabrics is liable to acurate ,and reduction and dissolution of

vat dys become insufficient and result in insufficient dyeing . the most recommendable

steaming time is 30-40 sec. a steaming for more than 40 sec. will cause over rduction of vat

dyes, and th normal dyeing will not be obtain. A shorter steaming is also resulted in

insufficient dyeing.

The reduction and dyeing mechanism of vat dyes , behaviour of leuco salt and kinds of vat

dyes will be described in the following,


1-Basic reaction of reduction and dyeing of vat dyes are shown in the following table,

Oxide leuco acid leuco salt oxide

Solubility In insoluble insoluble soluble insoluble

water

Dye ability on non non excellent non

cellulosic fibres

dye ability onto trace trace non trace

polyester fibre

Vat dyes, in general, require a reduction potential between -650mv and -1,000mV to convert

into leuco acid. To reduce all kinds of vat dyes , a reducing agent which has a reduction

potential of lower than -1,000 mV is necessary . from this point of view hydrosulphite is the

most suitable reducing agent.

2-Chemical change of leuco salt:

As stability of leuco salt of vat dyes is poor , when application temperature

amount of caustic soda and hydrosulphite,or quality of water are improper. The following

chemical changeare are liable to occure thus causing color change ,decreasing of color value

and poor reproducability

• Over reduction

When temperature is too high or concentration of hydrosulphite is abnormally high, over

reduction is liable to occur.

• Hydrolysis

When temperature is too high or concentration of caustic soda is abnormally high, over

reduction is liable to occur.


• Dehalogination

When temperature is too high or concentration of caustic soda and hydrosulphite is

abnormally high, dehalogination is liable to occur.

5-Behaviour of vat dyes in oxidizing and washing process

After steaming , the fabric moves into washers through a water seal ,but, the temperature of

water in water seal tends to increase and easily to be different in temperature distribution.

As they may cause unlevel dyeing ,it is necessary to keep overflow in a water seal.

H2O2 is the most common oxidizing agent ,when potassium dichromate

is applied as oxidizing agent ,chrome ions are liable to be absorbed onto the fabric , and these

ions cannot be eliminated completely during washing.

Since soaping time in an open width washer is generally short, it is

necessary to apply higher temperature as possible to eliminate impurities and dispersing

agents from fabric.


Continuous dyeing of polyester/cellulose blended

fabrics with disperse and reactive dyes.

Method: pad-dry-pad-steam

One bath method

Two bath method

In one bath process, both disperse and reactive dyes are padded in the same bath and

developed either together or separately onto the respective fibres. The former is called one

bath one step dyeing method and the later is called one bath two step dyeing method.

In two bath method ,disperse dyes and reactive dyes are applied onto polyester fibres and

cellulosic fibres respectively.

2We have studied the procedure of disperse dyes in last topic so now we will study about the

procedure and behavior of reactive dyes during continuous dyeing.

1- Reactivity of reactive dyes:

The reactivity of reactive dyes mainly depends upon the reactive

group. For example, dichlorotiazine dyes which exhibit high reactivity (procion MX) are said

to be 1000-100000 times than that of trichloropyrimidine dyes which are low reactive.

Reactivity of the reactive dyes which contains the same reactive

group vary depending upon the structure of dye chromophore .

A -Affinity of reactive dyes

Since continuous dyeing is carried out at remarkably shorter liquor

ratio than exaust dyeing, deep shades can be obtained with low affinity dyes.

The simple washing can be only applied in continuous dyeing. After dyeing.

B -Diffusion of reactive dyes into inside of the finre.

Due to their relatively low molecular weight , reactive dyes generally

show good diffusion properties. When the affinity is almost same as others, the dyes with

higher diffusion show higher color yield onto fibre.


Problems in continuous dyeing of polyester / blended fabrics with reactive dyes:

In continous dyeing , any sort of trouble during the process is liable to fail large volume of

fabric.

Various dyeing method are available for dyeing the cellulosic portion of polyester / cellulosic

blended fabricwith recative dyes but these common problems can be summarized by process

wise as given,

Process problems

1-Property of dye solubility

Preparation of 2-Compatibility of dyes and auxilaries

Solution. 3-Stability of dye solution

4-pH of dye solution

Padding 1-Tailing

2-Listing

Intermediate drying Migration of dyes

Storage of unfixed fabric Influence of gas

Alkali padding 1-Alkali,auxialri and color yeild

2-Bleeding

Steaming 1-Steaming conditions and color yield

2-Decomposition of dyes

Thermosoling 1-Thermosoling conditions and color yield

2-Decompositions of dyes


Problems in preparing of padding solution:

1-Dissolution of dyes:

Sumifix®, Sumifix® H, and Sumifix® supra dyesare generally made paste with a small

amount of hot water of 40C by kneading and then are dissolved adding hot water and stirring.

Disperse dyes, on the other hand , need to be dissolved and dispersed separately from

reactive dyes since dispersability is liable to to deteriorate by hot water, and eventually lead

to speck. When high concentration solution if reactive dyes are required , solubility can be

improved by addition of urea and dissolving agent.

Addition of urea not only influence solubility but also color yield of dyes.

2-Water to use :

Reactive dyes are generally effected by metallic ions existing in water to use , result in flate

shade. Soft water should be used for dyeing. However if water containing metallic ions is

obliged to be used.addition of 0.5-3g/l of sequestering agent is recommended.

3-Relation between pH of padding solution and stability of reactive dyes:

As the presence of alkali in dye padding solution in one bath one step method is liable to

activate and hydrolyze the reactive dyes. The temperature of dye padding solution should be

kept at 20-25°C.

Since no alkali is added to one bath two step dyeing method Sumifix H dyes can be applied

in this process. More over as there is no need to consider influence of alkali for disperase

dyes during pad-dry-thermosol process.

In one bath one step method as well as one bath two step method, the stability of dyes might

possibly decrease either by adding auxiliaries in padding solution or the quality of water to

be used.

Problems during padding process

1-Tailing

As the phenomenon of tailing has already been described In detail. Although various factors

affecting selective absorbtion of dyes are extremely complicated , the following factors might

be considered.

A-Dyes:

Affinity of dyes to fibre

Rate of penetration

Dye concentration

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B -fibres:

Kinds of fibres

Structure of weaving

Grade of pretreatment

Residual chemical

C- water to be used:

Contaminents such as metallic ions

D- additives:

Urea

Thickner

Alkali

Salts

Penetrating agnets

E- padding conditions :

Immersing

Immersing temperature

Pick-up style of squeezing

Size of padding bath.

Problems during drying process

After padding the fabric enters into a dryer and is dried. Unless temperature distribution , air

flow and air velocity are even adjusted inside of a dryer. In this process the major problem is

face-back , it is resulted in poor drying of IRs and if there is any fault in this dryer then the

dye particles cannot migrate properly and there is a shade fault. To avoid these problems

the dryer should be control precisely.

In comparison with other types of dyes,reactive dyes have a high hydrophilic property in

general and they are low affinity towards cellulosic fibres. Recative dyes have property to

migrate easily to the surface during drying. Further more ,as the surface of the fabrics are

liable to be dyed deeper whilst the inner part of the fabric become pale,it resulted in poor

dyeing due to the poor penetration and low quality of dye.

To avoid this a thickner like sodium algenate is added to the padding solution.


4-Problems during fixation process:

In continous dyeing of polester/cellulosic blended fabrics, fixation of disperse dyes on

polyester portion is mainly carried out by thermosoling process.

For fixation of reactive dyes on cellulosic portion of blends,on the other hand,various

fixation processes are available

Typical alkali solution Characteristics

Caustic soda (40Be) 10-15ml/l Suitable for pale shades

Glauber’s salt the more the salt is, the less the

Bleeding is

Caustic soda (40Be) 10-15ml/l Suitable for medium deep shades

Soda ash 20-40g/l Better reproducibility

Glauber’s salt anhydrous 200-300g/l

Caustic soda (40Be) 0-5ml/l Suitable for medium deep shades

Sodium silicate (50Be)200-400g/l Good reproducibility

Glauber’s salt anhydrous 200g/l

The higher the specific gravity is, the

less the bleeding

Sodium silicate (above 40Be) Suitable for medium deep shades

Good reproducibility


One bath pad dry thermofix method

Padding drying thermosoling washing Disperse dyes

Reactive dyes

Alkali

Conditions

Urea 50-100g/l

Migration inhibitors 0.5-1.0g/l

Penetrating agent 1-3ml/l

Sodium bicarbonate 10-20g/l

Padding 20-25°C

Pick-up 50-70%

Drying 110-130°C

Thermosoling 190-220°C

Time 60-120sec.

Washing open width soaper

Pad-steam

Box Process conditions

1 cold rinsing 20-30°C with over flow

2 warm rinsing 40-50°C with over flow

3 hot rinsing 60-70°C with over flow

4 boiled rinsing 80-100°C

5 6 soaping 95°C, 1-3g/l surfactant

7 8 warm rinsing 50-80°C

9 cold rinsing 20-30°C with over flow


One bath-two step pad thermosol alkali pad steam meth2od

Padding drying thermosoling padding steaming washing Disperse dyes

Reactive dyes

Conditions

Migration inhibitors 0.5-1g/l


Mono sodium phosphate(pH adjustment) 1g/l

Padding 20-25°C

Pick-up 50-70%

Drying 110-130°C


Time 60-120sec.

Glauber’s salt 250g/l

Caustic soda 10-20ml/l

Soda ash 0-20g/l

Reduction inhibitors 10g/l

Steaming 100-105°C

Time 20-30sec.2



One bath two step pad thermosol alkali pad cold fix method

Padding drying thermosoling padding cold fixation washing Disperse Alkali

Reactive

Conditions



Mono sodium phosphate(pH adjustment) 1g/l

Padding 20-25°C

Pick-up 50-70%

Drying 110-130°C


Time 60-120sec.

Alkali padding solution caustic soda (26-30Be)

Alkali padding temperature as indicated bellow

Pick-up 70-90%

Fixation 20-30°C , 45-90sec.

Or 40°C , 20-30 sec.

Or 50°C , 10-20sec.



One bath two step pad thermosol alkali shock method

Padding Drying Thermosoling Alkali Steaming Washing Disperse dyes

Reactive dyes

Conditions



Mono sodium phosphate(pH adjustment) 0.5-1g/l

Padding 20-25°C

Pick-up 50-70%

Drying 110-130°C


Time 60-120sec.

1-Glauber’s salt 250g/l

when fixation is carried out in a heating tank for 10-20 sec. at 95°C.

Caustic soda 50ml/l

Soda ash 0-50g/l

2-Sodium silicate 40-50Be

When fixation is carried out in the first and second boxes of open width soaper for 3-5 sec.

at 95°C.

Caustic soda 70ml/l

Soda ash 0-50g/l

Glauber’s salt 250g/l

Washing

It is the same as one bath pad dry thermosol method.


Problems caused by poor water quality

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