Analyse of Various Chemical Processing Steps in Term

8/7/2019 Analyse of Various Chemical Processing Steps in Term

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DIFFERENT CHEMICAL

PROCESSES

Kapil

Dyeing

Finishing

Namit

Pretreatment

Printing


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DYEINGy Dyeing is the process of imparting colours to a textile material in fibre,

yarn, cloth or garment form by treatment with a dye.

y Adye can generally be described as a colored substance that has anaffinity towards the substrate to which it is being applied. It is appliedto different substrate by using a different kind of machines.

y Different types of machines:- Pad Mangles

High Speed Beam Dyeing Machine

Jet Dyeing Machine

Jigger Dyeing Machine


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PAD-MANGLEy Introduction:- In this machine, DIP-NIP method is followed. The

main purpose of the mangle is to impregnate the material evenly with

dye liquor.


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FACTORS NEEDS TO BE

CONTROLLED:-S. No. Factors Guidelines Controlled by/

Observed by

1. Hardening of rubber

of bowls

75-85 Shore

Durometer

Hardness Meter

2. Time available forsaturation withliquor

Sufficient forthorough saturation

Speed

3. Methods of feedingthe fabric to the nip

Perpendicular to thenip

Threading arrangement

4. Tension on the fabric Just sufficient toensure smooth entry

Threading arrangement

5. Pressure on themangle rolls

Equal on both sides &sufficient for reqd.pick-up

Pressure gauges


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DRYING EQUIPMENTS:-y Many a sequence in cloth dyeing requires intermediate drying, i.e.

drying after padding but before fixation. Three types of machines areused for this purpose:-

Cylinder drying range

Hot flue Float dryer

PRECAUTIONS FOR GOOD RESULTS:- Use multi cylinder drying range and keep low steam pressure in first to

avoid shock drying.

In hot flue and float dryer use low speed fans in first chamber.

Add a suitable migration inhibitor to the padding solution(say, 1 g/l forthick cloth to 0.5 g/l for thin cloth).

Keep the wet pick-up at the mangle as low as possible.


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TO CHECK MIGRATION INDEX:-

y Take two pieces of cloth,(stitch one side),pad through thesolution, dry, develop. Compare these visually or measurethe reflectance of both the sides of these pieces. The

migration index is calculated as follow:-

M = 2k/(k+k)

Where, M= Migration index

k= k/s value of outside surfacek= k/s value of inside surface

In this test M=1 indicates no migration and M=2 indicates

complete migration.


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MIGRATION BECOME LARGE IF:-

y Pick-up is high

y Thickness of material is more

y Drying rate is high

y Polyester content in the blend is high

y Cloth is densely woven

y Proportion of finer particles in the pad-liquor is high.


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STEAMING/THERMOSOLING:-

y Some dyes can be fixed by steaming or thermosolingoperation.

Parameters Involved In Steaming:-y Temperaturey Speed

y Absence of air(for vat dyes)

Parameters Involved In THERMOSOL

ING:- Even distribution of temperature is necessary. Regular cleaning of the filters & airflow passage is

necessary to prevent blockage.


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AFTERTREATMENT:-y It involves Oxidation(for vat dye), Soaping & Final

rinsing.

Parameters To Be Controlled:- Conc. OfChemicals.

TemperatureAccording To Dye.

Time Of Treatment.

Flow Of Water In Rinsing & Efficiency Of Rinsing.


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HIGH TEMPERATURE BEAM DYEING

MACHINE:-y Polyester component of polyester containing fabrics is dyed

with High Temp. Beam Dyeing or Jet dyeing machine.


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CONDITIONS:- Fabric should be Properly heat set.

The selvedge should be plain & should not be dented orfolded.

Fabric tension must remain constant. There should be sufficient layers of cotton cloth wound on

the perforated beam before winding batch. This will avoidpossibility of perforation marks.

Batch size should be acc. To the cover factor, 20 cm foropen weave & 10 cm for closed weave fabric.

Liquor flow should be in one direction say inside-out.


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PRECAUTIONS:-

S. No. Parameters Precautions

1. Beam batching Ensure wrapping with filter fabricCloth should cover perforation length equally onboth sidesWinding under satisfactory tension

2. Rate of circulation Ensure good working of injector & main pumpDo not allow foam formation

3. Preparation of dyeliquor & additionto dye bath

Check for clear solution Or good dispersion bychromatography

4. Rate of heating Use automatic control, periodically checking

5. Pressure Record pressure periodically

6. Conditions of dyebath during dyeing

Notice deviation(check pH)

7. After treatment Follow suitable sequence


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JET DYEING MACHINE:-y In this machine, we can perform pretreatment and dyeing

of any fabric.

y It can perform high temperature dyeing(at 125c) at MLR of12:1.


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FACTORS NEED TO BE CONTROLED:-y Batch size

y Jet type

y Cloth speed

y Jet pressurey Liquor circulation

y Rate of heating/cooling

y Concentration Of auxiliaries

y Choice of compatible dye


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METHOD FOR CHECKING

OPTIMISATION OF COLOUR FEEDING:-

y Load machine with water and full fabric length.

y Prepare dye stock and auxiliary solution.

y Heat water in dye vessel and dye stock to 60c.

y Feed the stock solution to the dye vessel.y Continue to run the machine after adding dye stock for 2

min.

y Now stop the machine.

y

Open it and take out the fabric and cut about 1 meter ofit.

y Give one stroke to it, hang it warp way and allow it to dryat room temperature.

y Inspect the fabric for dye distribution.


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JIGGER DYEING MACHINE:-y This machine is used for dyeing woven fabrics.


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PRECAUTIONS:-

S. NO. PARAMETERS PRECAUTIONS

1. Batch size Weigh or measure the length accurately

2. Loading of jiggerStitch the fabric carefullyAvoid crease formation during loading

3. Colours/chemicals Weigh or measure accurately

4.Preparation ofDye-bath Dissolve the dyestuff as per standard procedure

5. Liquor ratio Maintain the MLR

6. TemperatureAutomatic temperature control is essentialOr Provide thermometer for manual control

7. After treatmentFollow suitable sequenceControl time, temp & pH

8. Drying Dry as soon as possible


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FINISHINGy Any operation for improving the appearance and

usefulness of a fabric after it leaves the loom or

knitting machine.


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FINISHING ON STENTER/FELT CALENDER

(CELLULOSE & PC BLEND FABRICS):-S. No. ITEMS PARAMETERS

TO CHECK

METHODSOF

CHECKING

STANDARDS ACTIONNECESSARY

1. Finish pastepreparation

Weighing Ofauxiliaries

Cooking time

Visual

Clock

At least one

hour

-----

2. Storage of paste

TemperatureViscosity

ThermometerStarchrefractometer

>80c Adjust thesteam flow

3. Applicationof finishingpaste

Moisturecontent offabric beforefinishingViscosity offinishing pastein pad-mangles

Feel orlaboratory test

Measurementof time reqd.for flow ofpaste throughATIRA

viscosity cup

About 6%

10%

around thestandard

To look intopreviousdryingprocessAdjust thetemperatureAdjust thesqueeze

pressure


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S. No. ITEMS PARAMETERS

TO CONTROL

METHODS OF

CHECKING

STANDARDS ACTION

NECESSARY

TemperaturePressure atpad-mangles

Wet pick-up

Thermometer

Pressure gauge

Weigh thefabric, dip inwater & passthroughmangle, weighagain andcalculateNoteconsumptionagainst lengthfinished

>85c

As per

standard

65 to 75% or

as per

standard for

the lot

Adjust thesteam flowAnalyserecord

Adjustpressure onsqueeze rolls


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S. No. ITEMS PARMETERS

TO CHECK

METHODS

OF

CHECKING

STANDARDS ACTION

NECESSARY

Moisturecontent of driedfabric

Moisturemeter orlaboratorytest

Around 6% Note steampressure &temp. in diff.chambersAdjust speedof steam flow

4. Expanders Before paddingmangles orbefore

stenter/feltcalendar

Visual No creaseformation

Adjustment ofexpanders orfabric

5. Fabricwidth

Delivery end ofthe machine

Measurementby tape

As fixed bythe mill

Adjust thewidth offabric onstretching

device


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ANTICREASE FINISHING:-S. No. ITEMS PARAMETERS

TO CHECK

METHODSOF

CHECKING

STANDARDS ACTIONNECESSARY

1. pH of clothforfinishing

-----Universalindicator

Neutral orslightly acidic -----

2. Finishing

pastepreparation

Mode of

addition ofchemicalsFinal volume

pH

-----

Measureheight ofsolutionpH paper or

meter

Add thermo-

setting resin& catalyst last

-----

-----

3. Applicationof resinfinishingsolution

Moisturecontent of f/cbefore finishingWet pick-upMangle

pressure

Feel orlaboratory test

Pressure

gauge

----- -----


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S. No. ITEMS PARAMETERS

TO CHECK

METHODS TOCHECK

STANDARD ACTIONNECESSARY

4.C

uring Temperature

Time

ThermometerThermo paper

Stop watchSpeedindicator

A

s fixed bythe mill 5%

As decidedby the mill

A

djust theworking ofheatersAdjust thespeed of themachine

The fabric is padded through the resin finishing solution, dried on the stenterand cured in the polymeriser.

The efficiency of curing can be checked as follow:-

Efficiency(%)= Nitrogen content in sample ANitrogen content in sample B

Sample A:- Sample of fabric after padding and drying.

Sample B:- Sample of fabric after padding ,drying ,curing and washing.


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CARBONISATION:-y This process involves the treatment of PC blend fabric with

70% sulphuric acid at room temperature. After treatmentfabric was rinsed with water, neutralised with soda ash andthen washed with water.

y Important process control during carbonization:-Quality of the acid:- Sulphuric acid should be checked for

presence of oxidising impurities by titrating with standardalkali.

Conc. And Temperature of Sulphuric acid:- The loss infibre bundle strength is higher with increase inconcentration And temperature of sulphuric acid.

Atwaddle meter and thermometer should be provided tomeasure concentration And temperature.


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WEIGHT REDUCTION:-y This process involves the use ofCAUSTIC SODAon

polyester & polyester containing blends to impart specialaesthetic properties to the material. 10% loss in weight isallowed.

yThree variables to control:-Temperature:- Rate of weight reduction increases with

increase in temperature. So, temperature should becarefully controlled.

PercentCaustic Soda:- The recipe is based on volumebasis. Hence amount of chemicals and volume of bathmust be controlled accurately.

Time:- This parameter is biased on first two parametersand weight loss level desired.


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REFERENCE:-y Process and quality control in chemical processing of

textiles byATIRA.

y

Internet source.


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BY:-

KAPIL SINGLA

Analyse of Various Chemical Processing Steps in Term

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