HISTROY OF DENIM

In fashion history, jeans and denim history continues to baffle. No one truly knows the perfect answer to where jeans began. As so often happens fashions often emerge together in various parts of the world and are the result of the sudden availability of a new fabric, cloth, dye or technique.

But we do know that the phrase denim jeans are thought to derive from several sources. No one is totally certain where the words come from. A majority of source books suggest that denim derives from the English translation of the South of France French phrase' serge de Nimes'. Denim fashion history is thus associated with Serge de Nimes.

It may well be that the fabric which was made in France also had a version made locally in England and was called by the same name of denim in the same way that Cheddar cheese is called cheddar all over the world. The Serge de Nîmes was originally a wool silk mix, twill weave. Certainly by the 19th century in England denim had a white warp and a navy woof (weft). Denim was considered a hard wearing sturdy fabric, ideal for heavy laboring.

When talking about denim the name Levi s is one of the first to be mentioned. Levi switch stands for Levi Strauss is normally called the forefather of jeans.

INTRODUCTION TO DENIM FABRIC

The structure of deim is a twill woven fabric, characterized by indigo dyed warp yarns, alternating with un-dyed cotton fill (weft) yarns. By looking closely at a pair of jeans, the pattern of diagonal lines created from the weave of the fabric can be seen. The warp runs along the length of the garment, while the fill (weft) yarns cross the width.

Most denim is still 100 percent cotton; a relatively small volume of polyester/cotton denim is produced and traded worldwide. It was originally a protective clothing fabric but now it has become accepted for leisurewear. More recently, other weaves have be3en used in lighter constructions. It is stiff and unyielding but softens in wear, and is very strong and hardwearing, but fades to whitish patches at creases or points of strain, hem edges, end, and creases easily. Used for causal style clothing, such as jeans, skirts, lightweight jackets and suits, shorts, children’s clothes, and for proactive clothing. Some denims made for dresses and less casual clothes contain more polyester; the colors are different, the fabric sometimes thinner, and it may fray slightly but will crease less.

There are different types of denim such as stretched denim, chinos, polyester blends, tinted denim, rain denim, Slub denim and crosshatch denim.

STRETCH DENIM:-

These denims assume the shape of the body, provide a perfect fit and adapt to your every move. They can be clubbed with different textures and finished to make them a category that stands out. The core spun yarns are used with blastomeric filaments from Lycra in the core, and with open-end cotton yarns on the cover.

Nevertheless, the classic comfortable pair of jeans in various shades of blue are still popular.

REVERSE DENIM:-

Reverse denim or Chameleon denim is known for its two-color effect. In this, the warp yarns on the face of the cloth are not dyed, but the filling yarns are colored. This effect is achieved by applying cross-linking finish to the raised warp yarn in the face of the fabric. After cross-linking, the fabric is piece dyed to get the reverse denim appearance.

SLUB DENIM:-

This trendy denim is woven with uneven yarns, giving your jeans a textured look. In this extra yarns are running in the warp direction. Due to the additional yarns running in the warp direction, you can see the lines running on the denim in the longitudinal direction.

CORDED DENIM:-

This is the result of crossing jeans with corduroys. It is a mixture of polyester and cotton fibers, and creases less than all cotton. Used for casual jackets, trousers, skirts, and children’s clothes.

POLYESTER BLENDS:-

Normally, denim is 100% cotton but now poly cotton blends are also widely used in denim for achieving various properties in the denim fabric such as for less creases and some wearing comfort.

Denim Manufactures in Pakistan

Company Name

 Business Address Tel No. Fax No.

 Name of Authorized CNIC No.

Representative

Siddiqsons Denim Mills

D-53, Textile Ave, S.I.T.E, Karachi

021-2577480

021-2569591 Mr. Tariq Rafi 42000-8453226-9

Pak Denim F-225, Street 5, Textile Ave S.I.T.E, Karachi

021-2566411

021-2566417  Dr. Mirza Ikhtiar Baig

42301-0393741-1

Al-Ameen Denim Mills Limited

A-4, Mangopir Rd, S.I.T.E, Karachi 

021-2578871

021-2562450  Amin Bandukda

42301-3905668-1

Artistics Denim Mills Limited

7,8 Sector 16, K.I.A, Karachi

021-5054629

021-5054652 Faisal Ahmed 42201-9731021-9

Mekotex Pvt Ltd 495, deh Landhi, National Highway, Karachi

021-5016649

021-5018298 Khalid A. Majeed

42201-8763789-9

X Pertex Denim C-45, S.I.T.E, Karachi

021-2573001

021-2564421 Ibrahim Weldon

42201-8324433-3

Kassim Textile Plot No. 63, Main National Highway, Karachi

021-5021161

021-5015261 Amanullah Kasim

42201-2037616-5

Baig Spinning Mills Limited

F-225, Street 5, Textile Ave S.I.T.E, Karachi 

021-2566411

021-2566417 Ishtiaq Baig 42301-51184347

S.M. Denim Mills D-11, South Avenue S.I.T.E, Karachi 

021-2562310

021-2562312 Shaheen Merchant

42301-2186211-5

Naveena Exports (Pvt.)

B21 Block 7/8 Banglore town main shara-e-faisal, Karachi

021-4310630

021-4310632 Asif Riaz Tata 42301-3765743-1

Abbas Spinning & Weaving

Plot St-1 Sector 18, K.I.A, Karachi 

111-111-279 021-5053449 Altaf Hussain Agha

42201-1089134-7

Rana Textile Mills Limited

Rafhan Mills Rd, Faisalabad

041-8717419

041-8711318 Rana Zahid Tauseef 

33100-0672286-7

Marfani Denim Plot 26 Sec 15 K.I.A, Karachi 

021-5070371

021-5058091 Mubeen Marfani

42301-9236972-7

InternationalPlot 48 Sec 28, K.I.A, Karachi 

021-5046045

021-5046044 Iqbal H. Agha 42301-0954658-3

Rajby Industries Plot 20 Sec 19, K.I.A, Karachi 

021-5064853

021-5060110 Nafees Sultan 42201-8220534-3

Classic Denim House 14 Sec 20, K.I.A, Karachi

021-5031794

021-5046109 Shazad Haroon

42301-105237-5

Azgard 9 Ltd Ismail Aiwan-e-Sci Ferozpur Lhr

111-786-645 111-786-645 Ahmed Humayun Sheikh

35201-8953938-7

PDL Fashion (Garments)

F-225, Street 5, Textile Ave S.I.T.E, Karachi 

021-2566411

021-2566417 Noreen Baig 42301-3042526-2

Indus Denim A/4A, Mangopir Rd S.I.T.E, Karachi 

021-2578030

021-2564950 Shabana Majeed

42201-4812646-4

Crescent Bahuman (Garments)

40/A Off Zafar Ali Rd Gulberg V LHR

042-5717651

042-5717652 Tariq Shafi 35201-5345709-9

Artistic Millener Pvt (Garments)

39 A Bl 6 P.e.c.h.s. Sh-e-Faisal, Karachi 

111-016-016 021-4547991 Yaqoob Ahmed

42201-4651073-5

Artistic Fabric mills (Garments)

39 A Bl 6 P.e.c.h.s. Sh-e-Faisal,

111-016-016 021-4547991 Iqbal Ahmed 42201-7565255-1

Karachi Soorty Denim Plot 26 Sec 23

K.I.A, Karachi 021-

5061912021-5061053 Shahid Soorty 42301-785025-

7Siddiqsons

(Garments)

D 54 Textile Avenue S.I.T.E, Karachi 

021-2566718

021-2588764 Abdullah Rafi 42201-1585507-1

International (Garments)

F-152, Hub River Rd S.I.T.E, Karachi 

021-2572735

021-2564582 Khalid A. Majeed

42201-8763789-9

7-A Ahmed Bl Garden Twn Lhr

042-5838782

042-5863623 Usman Tauseef

35201-2067895-4

Rana Textile Mills (Garments)

7-A Ahmed Bl Garden Twn Lhr

042-5838782

042-5863623 Rana Zahid 35201-0897064-4

Noor Fashion (Garments)

D 53 Textile Avenue S.I.T.E, Karachi 

021-2577480

021-2569591 Shahid Jameel

42301-8776093-4

Naveena Denim B21 Block 7/8 Banglore tw pechs, Karachi 

021-4310630

021-4310632 Masood Riaz Tata

42201-1896604-1

Naveena Denim B21 Block 7/8 Banglore tw pechs, Karachi 

021-4310630

021-4310632 Saquib Riaz tata

42201-5376605-2

U.S. Apperal Pvt 26 M Gulberg III Lhr

042-5340034

042-5832528 Mr. Siddiq Bhatti

35202-2836138-3

U.S. Apperal & Tex (Garments)

26 M Gulberg III Lhr

042-5340034

042-5832528 Mian Mohammad Ahsan

35202-2424092-3

U.S. Emporio (Garments)

Suit 30 leets Center Gul 3, Lhr

042-5783978

042-5783980 Muzammil Shahzad

35202-6921692-3

S.M. Traders (Garments)

D-11, South Avenue S.I.T.E, Karachi 

021-2562310

021-2562312 Iran Merchant 42301-2176616-5

Rajwani Apperal Ltd (Garments)

LA AC 2/1 Block 22 F.B Area, Karachi 

021-6344738

021-6344738 Farhan Rajwani

42301-3614712-7

Industries (Garments)

Plot 4 Sec B5 Khi Export Processing Zone Landhi Industrial Area, Karachi.

021-5082306

021-5082310 Amanullah Qasim

42201-6073983-3

Hantex Textile Plot 63 National Highway Landhi

021-5021161

021-5015261 Hanif Machera

42201-3930712-5

Mr. Denim Ltd 53 F M/s. Denim Industries Small Industrial Estate Lhr

042-5119032

042-5119033 Muneer Bhatti 35202-9316192-7

Karim Denim F-251 S.I.T.E, Karachi

021-2560568

021-2560569 Yousuf Karim 42201-1213609-9

AGI Casual 39-A Block 6, PECHS, Karachi.

111-016-016 021-4547991 Yaqoob Ahmed

42201-4651073-5

DENIM CONSTRUCTION

The actual definition of denim is merely. “A heavy-weight, twill, warps faced fabric”. Denim is defined as a 3/1 warp-faced twill fabric made from cotton open-end yarn.

The range of counts used in denim warp is 6s to 16s, and in the filling the range is 10s to 20s. The range of construction is 60-72 ppi and 32-44 epi. Denim is a heavy fabric and its weight ranges from 10 to 15 oz/sq yd; the most popular form being 14.5 oz/sq yd.

YARN FORMATION:-

Yarns may be formed using a ring, simulated ring or open end spinning system. Yarns themselves can be made in the following two ways.

Ring-spun Denim:

Ring-spun denim is the original denim fabric, made by using ring-spun yarns. It is the oldest of the three techniques and produces a tighter yarn core the tighter core makes it easier to ring-dye and thereby easier to produce abrasion on the final fabric.

This denim contains unique surface characteristics referred to as slubs, giving jeans a nice, authentic, vintage look. Mercerization can help to compact the yarn and improve ring-dyeing.

Open-end Denim:-

This is faster and less expensive to produce than the original ring-spun denims. Open-end denims create denim with a coarser look and feel. It is not nearly as cool as the original ring-spun denim. True authentic denim is a yarn dyed fabric.

YARN PREPARATION:-

The main consideration here in the yarn preparation step is whether or not cotton yarns will be mercerized. Mercerizing is a treatment that involves “Padding the yarn though a solution of caustic soda”. Mercerization causes the cotton fiber to swell and thus reduces the depth of penetration of the dyestuff into the fiber. This leads to a “ring-dyed” effect which will be advantageous if the fabric is to be stone or enzyme-washed.

In traditional denim, the filling yarns (weft yarns) are not prepared. Special styles may call for scouring, bleaching or yarn-dyeing prior to weaving.

WEAVING SYSTEM

There are three basic weaves in woven fabric design. These are plain weave, twill weave and satin weave.

Denim is a twill weave and a steep twill is produced by setting the wrap yarns closer tighter that the weft. Coarse yarns are used to construct both the warp and weft face in denim. However, denim weaves can be coarse (3/1), broken twill (3/1, staggered), find (2/1) or chambray (1/1). Denim is always a diagonal weave, rising to the right (most often) or to the left. Other weaves, notably the canvas weave, have also been used for jeans wear.

In a twill weave (used in denim) the fabric is constructed by interfacing warp and filing yarns in a progressive alternation, which creates a diagonal effect on the face or the right side of the fabric. It has a surface of diagonal, parallel ridges. In some twill weave fabric, the diagonal effect may also be seen clearly on the reverse of the fabric.

The twill is donated by using numbers above and below a line (such as 2/1). These numbers represent the position of the first en throughout the number of picks in the weave.

The numbers above and below the in also give a clue as to which yarn, the warp or the filling, will be seen more on the face of the fabric. If the number above the line is greater, the warp will predominate and the design is called warp face twill. If the numb are below the in is the greater, the filling yarn will predominate and the design is called a filling face twill. If both numbers are the same, the twill is can to be balanced.

We have either right-hand twill or left-hand twill depending on the direction of the weave.

Right-hand Twill: In a right-hand twill weave, the twill line or blue threads rise to the right hand twill line runs from lower left to upper right. This was the way denim was first woven.

Left-hand Twill: In the case of left-hand twill, the twill line rises to the left i.e. the twill runs from lower right to upper let, which creates softer-felling denim after washing. In general, left-hand twill denim will have softer hand than right-hand twill. This is due to the relaxation of twist in the yarn itself.

Broken Twill: In this type of weave, the diagonal twill line does not run in a straight line, it changes direction. Denim is made by weaving dyed yarns (called warp yarns) with undyed or filling yarns.

WEAVES

Various pattern of interlacing yarns for fabric woven on a loom. Denim weaves can be coarse (3/1), broken twill (3/1, staggered), fine (2/1) or chambray (1/1). Denim is always a

diagonal weave, rising to the right (most often) or to the left. Other waves have been used for jean wear, notably the canvas weave. 3 * 1 “Z” twill.

3 * 1 “Z” twill is the weave most commonly used for denim. It is a warp faced weave where each warp thread interlaces over 3 weft picks and under one the point of intersection move one to the right and one upward on succeeding picks. This causes a diagonal line to be formed in cloth, in this case from bottom left to top right which is way this twill is some time called 3*1 left to right twill instead of “Z” twill.

The angle of the twill line is the result of the relationship between the warp and the weft threads per cm. And because in twill denim there are always more ends than picks per cm the twill is steeper than 45 degree which enhances fabric appearance. All 3*1 weave “Z” twill must be pre-skewed.

3*1 “S” twill

In the past, 3*1”S” twill has been quite commonly used for denim but recently, especially for the more fashionable end uses, where 3*1 twill is required, it is being replaced by 3*1 “Z” twill.

The interlacing of 3*1 “S” twill is similar to 3*1 “Z” twill but in case the point intersection move one to the left and one upward on succeeding picks. The causes the diagonal line to be in the cloth from bottom right to top left which is way this twill is some time called 3*1 right to left twill instead of “S” twill.

TEXTILE FIBERS

The spelling fiber is used in common wealth countries and is some time used in United State as well is a class of materials that are continuous filament or are in discrete elongated pieces, similar to plants and animals, holding tissues together. Human uses for fibers are diverse. They can be spun into filaments, thread, string and rope. They can be used as a component of composite material. They can also be matted into sheets to make product such as paper are felt. Fibers are often used in the manufacturing of other materials.

TYPES OF TEXRILE FIBRES

A. Natural Fibers:-

I. Vegetable fibers

. Bamboo Fibers

. Coir from coconuts

. Cotton

. Hemp (mostly used in tope making)

. Jute

. Kapok

. Linen (made from flex)

. Ramie

. Seaweed

. Sisal

II. Animal fibers

. Alpaca

. Angora rabbit hair

. Camel hair

. Cashmere

. Silk

. Mohair

. Marino sheep

III. Mineral fibers

Mineral fibers comprise Asbestos. Asbestos is the only naturally occurring mineral fiber.

B. Manmade fibers:-

Manmade fiber may some from natural raw material or from synthetic chemicals. Many types of fibers are manufacture from natural cellulose including rayon, model and the more recently developed Lyocell. Fiber glass and optical fibers, which are made from purified natural quartz, or also manmade fibers that comes from natural raw materials. Synthetic fibers are a subset of manmade fibers which are based on synthetic chemicals (often from petrochemicals sources) rather than arising from natural materials by a purely physical process. Such fibers are quite often made from nylon polyester or acrylic polymers, although pure polycrylonitrile fibers are used to make carbon fibers. More exotic fibers have strong bonding between polymers chain (e.g. aramids).

TYPES OF FABRIC

a) Woven Fabrics :-

The fabric which is produced by the interlacement of two set of yarn called woven fabric. Yarn which is running along length wise called warp yarn and the yarn which is running width wise called weft yarn and the angle of interlacement between warp and weft is 90 degree.

b) Knitted Fabrics:-

A fabric produced by the process of knitting. Its structure is produced by the interloping of two yarn or more end of yarn.

c) Non-Woven Or Felted Fabrics:-

Non-woven sheet of matted materials of wool, hair, fur, some time in combination with certain manufactured fibers, made by combination of mechanical and chemical action, pressure, moisture and heat.

d) Blended Fabrics:-

A fabric that contain blended yarn (of the some fiber content) in the warp and weft filling.

TERMS RELATED TO FABRIC

1. Warp: -

I. The set of yarn in all woven fabrics, which run length wise and parallel to the selvedges and is interwoven with the filling.

II. The sheet of yarn would together on a beam for the purpose of weaving or warp knitting.

2. Weft:-

In a woven fabric, the yarn running from selvedges at right angle to the warp. Each crosswise length is called a pick.

3. Count:-

Count shows the coarseness and fineness of yarn it expresses in Ne, Tex, and denier. In the production denim fabric coarse yarn is used normally the count range is 6 to 30 Ne.

4. End:-

An individual warp yarn single or ply or cord.

5. Pick:-

An individual filling yarn.

6. Weight:-

As used with fabric, mass per unit area.

7. Strength:-

It is ability of fabric to resist being pulled or torn when subjected to stress or tension.

8. Elongation:-

When a fabric is subjected to a force it will stretch a certain degree. This stretching is described as the elongation of yarn in terms of %age of the yarn’s original length.

9. Abrasion:-

The wearing away of any part of the fabric by rubbing against another surface of fabric.

YARN USED FOR DENIM

Yarn specifications for production of Denim fabric are;

1) Minimum staple length: 2.7cm2) Proportion of short fibers (less than 12mm long): 40%3) Usual count range of denim warp yarn is 50-90 Tex4) And for weft yarn is 75-120 tex; finer yarn as fine as 25 tex in twill or plain

weaves are often used in denim shirts. 5) Twist factor; 4.5-5.0 for warp yarn, 4.2 for weft yarn

Manufacturing Process (Denim Plant)

Yarn Store

Warping

Indigo Dyeing Weft cum Sizing

Drawing In

Weaving

Singeing Shrinkage & Finishing

Inspection

Finished Cloth Store

WARPING

Warping is transferring many yarns form creel of single-end package. Forming parallel sheet of yarn wound on the a beam or section beam. Warping machines can process all types of materials including coarse and fine filament and staple yarns, monofilament, textured and smooth yarns, silk and other synthetic yarn such as glass.

A warn beam that is installed on weaving machine is known as weaver beam. A weaver beam contain thousand of ends, but in denim production a beam obtain from warping is known as section beam because denim is made from dyed yarn that’s why first section beam can be obtained and then these section beam are combined on the stage dyeing and sizing to get required number of ends for weaving process. In denim production initially the yarns are first dyed and then weaving process is carried out.

Rope dyeing.

Warping method used for both method of dyeing is different. The process used for roe dyeing is known as “BALL WARPING” and for slasher dyeing “DIRECT WARPING” method is used.

BALL WARPING SYSTEM

In this system of warping the yarns are wound on a large cylindrical roll in the form of twist less roe. The balls are used for dyeing of denim fabrics. After dyeing process the roll ends are separated and wound another warp beam usually the leasing comb and a collecting reed is used to achieve tangle free lease section. The warp beams so produced are then combined on sizing for applying the size past and making the weave beam.

BALL WARPING

Ball warping involves creeling multiple ends of yarns (normally 350 to 500) and collecting them into a untwisted rope for dyeing. This rope is wound onto a long cylinder called a long on a machine developed specifically for this purpose (the ball wrapper). Packager of warp yarn brought into the warping area one or two days prior to warping and allowed to condition to the ambient temperature and humidity of the area. They warp much easier if allowed to pre-condition in this manner.

All of the packages are then loaded into a creel. The packages are placed onto adapters which are located on steel support pins throughout the creel. These adapters support the packages of yarn and insured that the package is remains aligned to the tensioning devices. The most common type in use is the Wooden plug Adapter with a Rubber Friction Ring. One of the largest mills in USA did a study on all of different type of adapters and found the Wooden Plug to be the most effective, with the best ergonomic design of all of them. It is a relatively simple process to put a yarn package onto an adapter, it can be a quite difficult to remove the empty package. The next step involves threading the tensioners each having distinct advantages.

MACHINE SPECIFICATION OF BENNINGER’S WARPING MACHINE

Machine specifications of this warping machine are as under;

Model AGCH 9240 (year 2003).

Max. Creel Capacity 640. (V-Creel used).

Min. Creel Capacity 334.

Speed 20m/min to 1200m/min.

Pressure 200dalN to 600daN.

Tensioners Type Electronic.

I- Pressure set on the basis of fines and coarseness of the yarn count, i.e. more coarse more pressure is required to make the compact warping beam.

II- In warping process humidity factor plays an important role because if humidity is less then 80% than yarn breakage is more. For obtaining the required humidity humidification duct are installed.

III- To maintain the tension steel rods are used. Tension value is giving according to the yarn count.

IV- Electronic sensors are used to sense the yarn breakages.

Rope Dyeing Department

(Indigo Textile Mill)

MORRISON ROPE DYEING MACHINE

This is a manual machine. The rope dyeing machine is one of the finest in Pakistan; in fact it is the best.Two rope-dye ranges enable to produce pure indigo, sulfur bottom, sulfur top, and colored denim yarn. The yarn goes through scour/sulfur dye, wash boxes, indigo dye vats, over a skying device (to allow oxidation to occur), through additional wash boxes, over drying cans and then is coiled into tubes which are transferred to the long chain Beaming process.

There are 14 tanks in this machine starting from mercerization till Lubrication. The speed range of this machine is 0-30m/min with the production capacity of 2 sets in same time, hence the production per day become 36000x2=72000m at the speed of 25m/min. Normally the count range in Ne use in rope dyeing is (16s-6/s) OE and Slub both. The detailed description regarding each box will be presented on 25m/min to set a standard calculation. The complete detail is as under.

INDIGO DYES :

Indigo is the primary color of blue jeans, it is an important dyestuff with unique shade of blue color. The dye gives a brilliant and eye catching blue color to the fabric. Indigo has a low affinity for cotton, therefore deep blue dyeing is only possible when and oxidation is done several times. The color partially penetrates the yarn, and imparts the surface blue color. The dye then fades gradually fades from the surface of the fabric naturally.For manufacturing process of Indigo.

NATURAL INDIGO:

Indigo dye is an important dyestuff with a distinctive blue color. The natural dye comes from several species of plants. A variety of plants have provided indigo throughout history, but most natural indigo is obtained from plants in the genus Indigo era, which are native to the tropics. In temperate climates indigo can be obtained from wood (Isanti’s tinctoria) and dyer's knotweed (Polygonum tinctorum), although the Indigo era species yield more dye. The primary commercial indigo species in Asia was true indigo (Indigo era tinctoria, also known as Indigo era sumatrana). In Central and South America the two species Indigo era suifruticosa and Indigo era arrecta (Natal indigo) were the most important.

PROPERTIES OF INDIGO:Indigo is an insoluble dye, a dark blue crystalline powder, which has to be reduced with suitable reducing agents to make it soluble in water, Indigo works by a chemical reaction called oxidation reduction. Indigo does not dissolve in water. It must be reduced — i.e. the oxygen must be removed— in the presence of alkali by a reducing agent such as theorem dioxide (thiox), sodium hydrosulfite, Zinc, or bacteria. Upon reduction, indigo becomes colorless and water soluble. In this state, indigo has a high affinity for cellulosic fibers and enters the open spaces of the fiber. The dyed fibers are then exposed to air, which oxidizes the dye molecule back to its insoluble form. The insoluble dye particles are trapped inside the fiber, coloring them permanently blue. Unlike most dyes, indigo forms a mechanical, not chemical, bond.

A. Indigo is a dark blue crystalline powder that melts at 390°–392°C.B. It is insoluble in water, alcohol, or ether but soluble in chloroform, nitrobenzene, or concentrated sulfuric acid.

C. The chemical structure of indigo corresponds to the formula C16H10N2O2.

  Complete Chemistry of Indigo

C. The naturally occurring substance is indicant, which is colorless and soluble in water.

Indicant can easily be hydrolyzed to glucose and indoxyl.E. Mild oxidation, such as exposure to air, converts indoxyl to indigo. 

F. Indigo is a frequency range of visible light, from 440 to 420 nanometers in wavelength, placing it between blue and violet.

Creel for Rope Dyeing

After warping 24-Balls on creel are put to start dyeing. 12-Balls = one set, 24-Balls = two sets.

Pretreatment Box:-

The capacity of this box is 2800lit. Mostly Pre-wetting/Mercerizing with 1Be-20Be range by using 50Be caustic soda liquid is done here. In addition to increase wet ability wetting/ mercerizing agent are used but as a facility to set sensor on over flow, this tank can use on 2000lit, 1800lit, 1500lit and 1136lit. This box is also serving for Sulfur Bottoming at any of the above mentioned set levels. At full volume the Airing time and Dipping time is 48.4sec respectively.

Wash Boxes (After Pretreatment) :-

There are 3 wash boxes in arrow after the pretreatment box, with the workable volume of 1325lit each. In this area use any chemical is not used. The first 2 washes can be set on temperature to 60oC or less but last box works only on RT. The Airing Time and Dipping Time at this point is 22.88sec each and 31.68sec for the last wash box to first dye box.

Dye Boxes:-

There are 6 dye boxes having capacity of 3650lit each at full volume hence full capacity becomes 21900lit. Normally full volume is used in all dye boxes when pure indigo is dyed.

For Sulfur Bottoming, Topping and Pure Black, first and sixth (last) dye bath are used where we have steam coiler to raise the temperature which is normally required in case for sulfur dyeing; here we the capacity to us adjustable volume on over flow is used. The Airing Timing for first 5 dye boxes are 105.6sec each and for 6th dye box is 160.16sec and Dipping Time for all dye boxes is 24.64sec.The type of dyes use in dyeing are indigo and sulfur dyes, caustic soda liquid 50% dispersing agent, antifoaming agent, wetting/mercerizing agent, etc.

Wash Boxes (After Dye Boxes):-

After dyeing again 3 washes with exactly same pattern and parameters mentioned above in wash boxes before dyeing are installed. The 2nd wash box in this sequence also can

be used for chemical fixation when we dye pure black. In this box we use formic acid with the combination of hydrogen peroxide to control pH and increase fixation chemically.

Lubrication Tank:-

In continuation, last box is for lubrication of 1325litre volume. The Dipping Time is 26.4sec and Airing Time is 12sec. In this box, non-ionic softener with formic acid and urea to regain moisture are used.

After that, there 36 drying canes through which ropes are passed and then they are reside in coiler canes for further treatment.

Other then that in this machine, Pneumatic Actuators, steam in let and out-lets in several boxes and other places on machine, and in the last but not least Padder pressure sequences and of course Tension parameters to set machine in every dimension are equipped.

In Support of all those boxes in machine, there is complete color kitchen having every chemical. For supporting mercerization, 4 feeding tanks, each having feeding capacity of 757lit are equipped. For Sulfur dyes, 2 tanks of 1323lit each having steam coiler facility and for Indigo, 2 feeding tanks having 757lit capacity of each tank are equipped. For softener and fixation, 2 tanks for each purpose with the capacity of 947lit each tank and for chemical springing, 2 tanks with 100lit each capacity are equipped. Other then that since there is very large capacity of liquor therefore also 2 very huge storage tanks having the capacity of 25000lit each for indigo and contaminated indigo

Separately are equipped. In small storage tanks there is 1 tank of 5000lit for Black, I tank for premixing of indigo feeding.For all dye and chemical feed, PULSA FEEDER PUMPS are used. For other chemical supplies pH control system is used to maintain their feeds.

Drying:-

In the rope dyeing, the drying is carried out by cylinder dryers, on which the set of ropes are passed over these.

The lists of chemical use in dyeing are:

Chemical Name Description Company

Mercerol QWLF Mercerizing Agent ClarinetALkapol ASD Wetting Agent Alka Traders Caustic soda 50% Liquid - Sitara Group Premasol NF Anti Foaming Agent BASFSetamol BL Dispersing Agent BASFIndigo Dye Stuff ChinaSodium Hydro Sulfide Reducer for indigo BASFSulfur Black BR-200% Dye Stuff ChinaSodium Sulfide Reducer for S. Black ChinaFormic Acid for pH control Tufail Hydrogen peroxide for Oxidation LocalImmacol-C Lubrication ClarinetAlkasoft 5200 Paste Softener Alka TradersUrea Moisture regains Local

TECHNICAL CONSIDERATIONS IN ROPE DYEING FOR

INDIGO DYED DENIM

The passage of yarn in rope dyeing is as follows:

Pre-scouring –>hot wash–>cold wash –> Dye baths–> hot wash–>cold wash–> application of softener

Let’s discuss these processes one by one:

PER-SCOURING:

1. The objectives of pre-scouring are the removal of wax content from cotton, removal of trapped air from cotton yarn and Making yarn wet

2. This is done at 90 o C

3. We use the following ingredients at pre-scouring stage:

4. CAUSTIC SODA :

Its quantity depends upon the quality of cotton fibres used in the mixing. Generally we take 2-4% of caustic soda. It removes the wax by the action of soapanification.

WETTING AGENT:

It is anionic in nature

SEQUESTING AGENT:

Even with the use of water softening, it is very difficult to find the desired softness in water (about 2-3 ppm). So we use the agent to make the water soft.

HOT WASH:

As some caustic is carried by the yarn after pre-scouring, so hot water is given at 70-80C. If this is not done, this yarn will go into the dye-bath which will change the pH of the dye-bath.

COLD WASH:

After hot wash, yarn temperature is more. To bring it back to its room temperature, cold wash is given to it.

INDIGO DYEING

1. Indigo is not a perfect vat color. It may be called a trash vat color. The constant of substantively for other colors is 30, for indigo it is only 2.7. So there is a need of 5 to 6 dye baths and make the use of multi-dip and multi-nip facility to increase the penetration. 2. The dyeing is done at room temperature as indigo belongs to Ik class of vat dyes, where dyeing is done at room temperature and oxidation is done by air only and not by chemicals. If oxidizing agents are used, they will cause stripping of colors. 3. Indigo is not soluble in water. So it is reduced with Sodium Hydrosulphide. Then caustic soda is added to make sodium salt of vat colors to make it soluble. To reduce 1 kg of Indigo, 700 gms of sodium hydrosulphide is required. However some extra SHS needs to be taken to avoid some decomposition of SHS. Practically it is prepared in the following sequence Take indigo -Add caustic -Then reducing agent 4. When caustic is added to indigo, it is an exothermic reaction. It is allowed to cool down, then before sending it to feeder; sodium hydro-supplied is added. Reducing agent is not added first as it will be decomposed first, so consumption of it will increase. It is also not advisable to take solubalised vat, as offered by some companies due to the following reasons: a. If it is used after 6 months, there will be a decomposition of sod. Hydrosulphide. It will become partially soluble. Then to make it soluble again, more SHS has to be added. b. Transportation is difficult c. Cost is more 5. Feeding System Rat of flow of yarn is given by ((No of ropes x no of ends x speed of machine)/ count x 1.693 x 1000) in kg of yarn / minute So we can determine the rate of feed of indigo. It is very important that replenishment of indigo is there as any variation will result in the change of shade and also if level is more, there is a problem of over-flow. 6. If total capacity of dye bath for example is 15000 liters, then circulation must be 3 times the volume. If it is less then there are 100% chances of getting a lighter shade. 7. Core and ring dyeing effect. This effect is obtained by multidip-multinip facility. 8. PH of the Dye bath should be kept in between 10.5-11.5. At this pH, sodium salt of Indigo is mono phenolic form. At this form, the strike rate of dye is very high. So after washing, there will be a better dye effect. At pH 11.5 to 11.7, at this affinity is less, so dye effect will be less prominent. PH is controlled by the addition of caustic soda. 9. Testing of Hydro.

TOTAL HYDRO:

We take 10 ml of indigo with SHS in 30-35 ml of water. It is set for one minute and shaken. As air will decompose SHS. So vacuum created will fetch the water from above. If 3 ml of water is required, then concentration of hydro is 3 gpl. As a thumb rule, concentration of total hydro should be min. 1.5 gpl.

REDUCED HYDRO:

It is the hydro that is used for the reduction of Indigo. It should be around 0.7 (1000 kg of Indigo needs 700 kg of hydro to reduce it). For testing we take 10 ml of dye solution and 30 ml of water and 5-6 drops of 40% formaldehyde and shake it for one minute. The water that goes gives the readings of the reduced hydro. Total Hydro- Reduced Hydro = free hydro If Total hydro is min. 1.5 gm/lit. Then free hydro must be min. 0.5 gms/ liter which act as buffer 10. Also hydro reduction capacity is measured by mV meter which measures the Redox Potential. It should be around 760-800 through the day, the redox potential should be +- 20 mV of the norm. If it is more then the process control is a failure. Caustic–> It is around 0.4 to 0.5 times the hydro used.

WASHING:

Rubbing fastness of indigo is very important. On a scale of (1-4), it is 2. Washing is done to improve the rubbing fastness. Wash at 60 deg.–> Wash at 60 deg.–> Wash at room temperature–> wash with softener

WHY SOFTNER:

1. The rope is going to be opened at Long Chain Beamer. It the softener is not used, opening will be hampered. 2. It is generally 1.2% of the weight of the yarn. It is a cationic softener. It is always having pH in the range of 4 to 55. Softening is done at room temperature. If high temperature is used there is always some chance of tendering of yarn. 3. Concept of Buffer pH is given by Virkler USA, they say by addition of this, there is 40% less consumption of Indigo for same shade depth. 4. Metering Consumption If solution is of 900 liters 10% Indigo–>90 liters Hydro–> 90*.7 = 63 kg Caustic–> 63*0.445= 28 kg.

It belongs to a VAT class of dyes. It has a dark blue color wit a bronze luster. It belongs to KI class of dyes. In this class, dyeing is done at cold and air oxidation is done to reoxidise the dye. It can be applied on both cellulosic and protein fibres. For protein fibres, a weaker

alkaline solution is used. It can be reduced by NaOH and Na2SO4 in water to give monophenolate and biphenolate ions as complete solution. Reduced form of Indigo is called leuco indigo. Leuco has got low affinity for cellulosic fibres. Dye take up can be improved by: 1. Either mercerization of cellulosic fibres before by dyeing 2. Or by adopting multidip, squeeze and airing process, so that dye is coated on the fibre layer by layer Indigo can be further developed into Halogenated derivatives and sulphonated derivatives. Halogenated derivatives give better fastness properties and brighter shades, whereas sulphonated derivatives gives a soluble blue dye, good dye and is applicable on protein fibres.

reaction : Image 1 Although indigo is a vat dye, it can be regarded as a ‘trash’ dye, the dyeing and fastness properties are in no way comparable to other class of vat dyes. It is due to these properties that make it an excellent dye for denim. The on tone fading and the bleach down properties of indigo blue has generated a lot of denim jeans fashions like stone, ice faded looks, etc. These special effects cannot be simulated by the other classes of dyes. During Preparatiuon of stock vat, the following points must be remembered: 1. Vatting temperature should be as close to room temperature as possible. 2. Stirring should be minimum, unnecessary stirring affects the stability of reduced vat. 3. Volume of the reduced vat should be kept constant for every stock vat batch, as the constant volume will ensure a constant replenishing amount. For rope dyeing system, with chemical replenishment with Stock replenishment Indigo: NaOH: Na2SO4: 1:0.8:0.8 without stock replenishment indigo: NaOH: Na2SO4: 1:1:1.2

CHEMICAL FEEDING:

NaOH: Na2SO4: : 1: 1.2-1.6 i.e. for approximately 60 gpl of NaOH–> 120 gpl of hydro is required

INDIGO DYEING PROCESS CONTROL

Concentration of Hydrosulphite:

It is measured by vatometer. It should be from 1.5 gpl to 2.5gpl, or by redox potential of dye bath which should be from -730 mV to -860 mV.

Caustic Soda or pH value:

Should be from 11.5-12.5

Dye concentration in Dye bath:

It is measured by spectrophotometer. It should be in g/l

Guidelines:

High Indigo Concentration –> Shade is greener and lighter Low Indigo Concentration –> Shade is dull and Red. High pH or Caustic Concentration –> Redder and lighter Low pH or caustic concentration –> greener and darker

Dipping Time:

Longer the dipping time, better will be the penetration and lesser will be the ring dyeing effect. It varies from 15-22 seconds.

Squeeze Pressure:

High pressure will lead to lower wet pick up and result in lesser color and better penetration. At rope dyeing, squeeze pressure is 5-10 tones, i.e. wet pick up is as low as 60%. Hardness of squeeze roller is about 70-75 deg. shores. It squeeze rolls are too hard then there are chances of slippage and uneven yarn tension.. If squeeze rollers are too soft then shading will occur. Surface of the squeeze rolls should be ground twice a year.

Airing Time:

It should be 60-75 seconds. Longer airing time results in high tension on the yarn and subsequent processes will become difficult.

Drying:

Insufficient or unevenly dried yarns will result in poor Rebeaming Calculation of Replenishing Dye feed/min Conc. of stock vat is g/l= 90 range speed in yards/min=25 count = 7s total ends = 4100

Wt of yarn dyed /min= (4100*25*1000)/ (7*840*202) = 7924 gms shade desired = 2% Amount of dye to be replenished/min= 158.5 gms

Effect of pH:

At pH of 10.5 to 11.5, there will be formation of more monophenolate ions, which lead to higher color yield, as strike rate of the dye to the yarn bundle is very high, and wash down activities will be very good. At pH higher than this, dye penetration will be less and wash down characteristics are also poor.

Testing:

1. Alkalinity in Dye Bath Liquor Pipet 10.0 ml of vat liquor into 100ml of distilled water in a 150 ml beaker. place under continuous agitation and insert the electrodes of a pH meter calibrated at pH 7.0 with standard buffer solution. Titrate with tenth normal HCl (0.1 HCl) to pH 7.0 (ml = A) calculate g/l of NaOH = A *0.40

2. Hydro in Dye bath Liquor Add 2 ml of 37% HCHO to 150 ml beaker. Add 2 ml of dye range liquor. Add 6 ml of 25% glacial acetic acid solution prepared by diluting 1 part acid with 3 parts water. Add 2 ml of starch/KI indicator. Add ml of water. Titrate with 0.046 N (prepared by diluting 460 ml of 0.1 N Iodine to one liter) solution until the color changes from emerald green to bluish purple. G/l of hydro= mo of 0.046N of Iodine

Importance of High Concentration of Free Hydrosulphite

The clearest shades with minimum reddish streaks are observed at by relatively high conc. of hydrosulphite. On the other side, with lack of hydrosulphite, the leuco indigo is less dissolved and thereby adheres to a greater extent to the fibres. With lack of hydrosulphite furthermore, the amount of unreduced dyestuff by oxidation at the upper level of the liquor and through activation of unfixed dyestuff, gets separated from the fibrous material would constantly rise as the reducing agent for creating leucoform would be missing. Under these circumstances a reddish bronze like shade results due to dispersion of not reduced dyestuff in the yarn. The min. proportion of hydrosulphite should be around 1.3 to 1.5 gpl in case of rope dyeing and 3-4 gpl in case of sheet dyeing. Also to avoid the lack of hydrosulphite or Indigo at certain places in the immersion, vat, the whole quantity of the liquor should be circulated 2-3 times every hour.

RE-BEAMING DEPARTMENT

After long detail of Rope Dyeing, the 3rd dept. known as Re-Beaming Dept. Here they re-open the rope and winds it on beam so what they can be sized on next step. They have 8 Re-Beaming machines with the comb capacity of 380-429 ends. And there daily production is ~50,000m.

(RE-BBEAMING MACHINE)

WARP SIZING

In the production of woven fabrics, warp yarns are sized with a protective coating to improve waving efficiency. Movement of the warp yarn through the heddles and mechanical actions during insertion of filling creates a great deal of abrasive stresses on these yarns. Unprotected, the warp yarn cannot withstand the rigors of weaving. They will break causing machine to stop and thus be responsible for loss of productivity. Weaving efficiencies are vastly improved when the warp is properly sized. Size or sizing is defined as the warp yarn for weaving protection. Size usually consists of water soluble, film forming macromolecule and a lubricant.

Requirement of a Good Size

The quality required of a good size depends, in the main, on what type of yarn is in the warp. For example, fine count spun yarns require more protection than do plied yarns of course spun yarns.

a. Spun Yarns:-

Spun yarns require that size contribute to yarn strength and that the protruding fiber ends be glued to make its less hairy. To do this, the sizing solution must have a high prevent penetration into the yarn. Optimum protection is afforded when most of the size remains on the yarn surface to coat the yarn and glue down the protruding hairs.

b. Continuous Filament Yarns:-

These yarns are strong to being with. The main purpose of the size is to tie all of the filaments together. Stray filaments are easily broken; however, as part of a single, large bundle, the yarn is strong and abrasion resistant. Viscosity needs to be low so that solution penetrates into the yarn bundle. Also the better the adhesion between the size and the fiber, the better is the protection.

c. General Requirements of a Good Size:-

The general requirements of a good size paste are as follows:

Tensile Strength Abrasion Resistant Inexpensive Good adhesion Flexible Extensible Not support bacteria Easily removed

Sources of Sizing Compounds:-

The following list summarizes the materials that can be used as warp sizes. Some of the base materials are used either alone or as additives to impart desirable properties to other bases. When designing the desizing step, it is important to know what base size was used. Each film-former has its own optimum conditions for effective removal. Knowledge of the chemistry of the film-formers will make it easier for one to grasp how to best desize specific fabrics. Starches Flours Polyvinyl alcohol Dextrin Gums Polyacrylic Acid Glue Gelatins Carboxymethyl Cellulose Synthetic Polymers and Co-polymers

Of the bases listed above, starch and polyvinyl alcohol are the polymers most often used when sizing spun yarns. Synthetic polymers work best on filaments yarns. These polymers at times are blended with starch to improve starch’s adhesion fibers.

STRACH

Historically, starches and flours have been the film-formers of choice for textile sizing. The key difference between flours and starches is the gummy substance gluten; starches are flours which have had the gluten removed. Nature produces a wide variety of starches as a white granular substance found in seeds, roots and stem piths of growing plants. Flours or meal is leached with water (to remove the gluten) leaving the white, free-flowing granule which has limited solubility in cold water.

A. Sources of Starches Used as Textile Size:-

Listed below are the natural sources of starches of starch as textile size:

Corn (maize) Potato (farina) Tapioca (cassava) Sago Wheat Rice Sweet Potato Yucca

B. Chemical Constitution:-

Starch polymers are carbohydrates composed of repeating anhydroglucose units linked together by an alpha glucosidal linkage. The structure contains two secondary hydroxyls at the -2, 3-positions and a primary hydroxyl at the -6- position. The alpha linkage is an acetyl formed by the linkage of the hydroxyl at the -1- position with the -4- position of another. This gives rise to a linear polymer called Amylose. Branching can occur when an acetyl linkage between the -1- positions of one ring forms with the -6- position of another. Highly branched polymers are called Amyl pectin. The differences between amylose and amyl pectin are: Amylose is a linear polymer, molecular weight range 100,000 to 300,000, found in the interior of the starch granule and accounts for 19 to 26% of the weight. It is soluble in hot water; however, when the solution is cooled, it will form strong hydrogen bond between adjacent chains making if difficult to re-solubalised. Amyl pectin is the major component of starch and comprises the outer sheath of the granule. A highly branched, high MW polymer (1.6M), less water soluble than amylose.

Creel Loading:

The warper beam should be loaded on the creel so that these are parallel to order and evenly tensioned. Otherwise loose and tight ends will be wound on the beam which afterwards create problems in working of warp stop motion and dye streaks after dyeing.

Squeeze roller dressing:

The occupation of threads on squeeze roller should be 4-60% for proper penetration of size paste.

Teflon coating:

First few drying cylinders should Teflon coated, otherwise the yarn sheet will stick on cylinders and the ends will break.

Denting the expending comb:

The threads should be evenly distributed and dented in the comb properly to get the uniformly distributed sheet on the beam and therefore, the crossing will be minimized.

Beam density:

The pressure of lorry should be adjusted to get the beam with density value 60. When checked by hardness tester manual observation is that it should be hard to press (60 cu. In/lbs).

Carboxymethyl Cellulose (CMC):

Carboxymethyl cellulose in made by the reaction of sodium chloroacetate with cellulose. Lumbering by-productions, namely stumps, limbs etc. are ground-up, soaked with alkali and made to react with sodium chloroacetate. The degree of substitution can be controlled up to a maximum of 3 Carboxymethyl groups per anhydroglouce unit. For textile sizes, the DNS in usually 1.5.

Advantage and disadvantages over starch:

CMC is soluble in clod water and does not require a cooking step. Solutions remain fluid at room temperature and don’t retrograde. They can be reheated and cooled repeated, it is easy to remove and rediscover CMC size in warm water. CMC like starch supports mildew on strong of fabrics. It is more expensive than starch.

POLYVIYL ALCOHOL (PVA):

POLYVIYL ALCOHOL comes in several grades, differing in molecular weight and solution viscosity. Polyvinyl alcohol is manufactured by hydrolyzing polyvinyl acetate. The reason is because vinyl alcohol does not exist as a monomer, tautomerization favors the more stable acetaldehyde. Polyvinyl acetate, however, can be hydrolyzed into polyvinyl alcohol under acidic or basic conditions. Either method leaves undesirable salts that are difficult to remove.

The preferred commercial method of hydrolyzing polyvinyl acetate is use catalytic amounts of sodium meth oxide in methanol. The reaction proceeds, through trans-etherification where by product, methyl acetate, is easy to remove by distillation. The parent polyvinyl acetate from branches during polymerization by a chain transfer mechanism at the methyl group of the ester. However, the corresponding polyvinyl alcohol is lower in molecular weight and virtually linear. The branch points are ester linkages which are broken molecular weight fragments.

GRADES OF PVA AVAILABLE AAS TEXTILE SIZE:

Commercial PVA in grades which effect the molecular weight and degree of hydrolysis. For textile size application three grades are mainly used. These are summarized below:

Hydrolyzed Solution TemperatureFully Hydrolyzed 99 boiling waterIntermediate Hydrolyzed 95 160oFPartially Hydrolyzed 88 120oFSolution viscosities are mainly a function of molecular weight. Low viscosities are produced with low molecular weight polymers in the 25-to 35,000 range whereas polymers in the 250-to 300,000 range give high viscosity solutions.

FILM PROPERTIES:

Dried film properties area a function of both molecular weight and the degree of hydrolysis. Super tough films are formed from high molecular weight, fully hydrolyzed polymers, as a textile size, the adhesiveness and toughness of the dried film are advantages which have been responsible for its growing usage, especially on spun yarns. Added pluses area easy handling and the ability to cool and reheat (doesn’t retrograde). Because of the film properties, less add-on required to produce a good weaving warp.

SIZING DEPARTMENT

There are automatic computerized machines (Benniger). Here they can load 2 sets at a time. In this machine, 2 sizing boxes having capacity of 400x2lit in which warp sheet passes through in such a way that 6 beams (half sheet) pass through 1st side combine together for weave able beams. The avg. maximum workable speed is 45 to 60m/min. The avg, production of this dept. per day is 50,000m. Folling chemical are currently using in sizing are:

Chemical name Description CompanyTexo-film maize starch Starch RafhanArca base Acrylic Binder FFD BrothersSize-o-Bond Sizing Softener FFD Brothers

CHECKING AND MONITORING THE SIZING PROCESS

Programming the machine:

The easy to follow visualization and recipe management, in which all the machine and textile parameters are strode, permit fast and simple programming.

Sizing Monitoring:

The sizing process is automatically monitored. All set point are specified with upper and lower tolerance limits. Deviations from the programmed value are displayed at once and instructions for their rectification are explained in the language of the operator.

Controlled Tension:

The special arrangement of the roller in the 3-roller set prevents threads from slipping through and keeps the thread constant in the dry split section when changing beams.

Reproducible size cooking:

The SIZEMIX cooker, equipped with a high powered agitator ensures homogeneous liquor. The cooker is programmed via the size recipe at the machine PC. In this way, cooking temperature, water quantity and cooking time are optionally from the PC or directly at the cooker.Proposed numbers of end/inch in size box.The table describes the numbers of end/inch of ring spun an open end yarn in size box according to count.

MAXIMUM ENDS/INCH IN SIZE BOX

Yarn count Ring spun Open end

10 35 31

20 50 45

25 56 50

30 62 56

35 66 60

40 71 64

50 80 72

Viscosity of size paste:

Viscosity of size paste should not decimate from required value. Less viscose paste makes adhesion of size material well but coating on the surface of the yarn is not done properly.

While paste with higher viscosity coats the yarn very well but adhesion of paste into the core of yarn in terms of increasing its strength is not done properly.Viscosity can be checked by using simple VISCO CUP. It should be of copper or stainless steel for good size mix, its duration to be fully drained in 15-20 sec hourly checking I the size box is practiced. Viscous cup so easy to use. A very sophisticated and expensive viscosity meter is not only unnecessary but rather inconvenient for the industry.

Size box temperature control:

The degree of size penetration and coating depends not only on the nature of yarn and the size solution but also upon the viscosity which in turn largely depends on the temperature. It should be about 200 FO- 206Fo. Fluctuation should be 3 FO. The temperature gauge should be installed on the size box. Perforated copper pipe lining is laid in the bottom of size box to supply the stream for keeping the paste warm up to the above mentioned temperature. Low temperature will make gelling of paste which will not penetrate through the yarn and higher temperature create thinning of the size paste which is also unsuitable to be used as stickly paste. So to maintain the temperature with rich PVA or CMC then temperature of 75CO TO 80Coin sufficient.

Stretch percentage:

Cotton yarns have 6-7 elongation at break. So at slasher, the elongation of sized cotton yarn should not be below 4-5% at any cost, in other words, the stretch should be applied to the yarn 12%in different zones during sizing process. This stretch should be checked randomly; otherwise its variation will increases warp breaks on weaving machines. Other quality control parameters which are also very important area as under.

(Sizing Box)

WEAVING

Weaving is the interlacing of warp filling yarns perpendicular to each other at 90 degree. These are practically an endless number of ways of interlacing warp and filing yarn. WEAVING MACHINES (LOOMS):

The weaving machines are named after their filling insertion system. Schematics of the filling insertion systems that are used in the market are;

I- Shuttle II- ProjectileIII- Rigid rapier

IV- Flexible rapierV- Air jetVI- Water jet

Based on the filling insertion system, the weaving machine can be classified as shuttle and shuttle less weaving machines. Shuttle looms have been used for centuries to make woven fabrics. LOOM MOTIONS:

There are three types of loom motion which are given below;

I- Primary Loom Motions

Shedding Picking Beating Take-up motion Let-off motion

II- Secondary Motion

Warp stop motion Weft stop motion Warp protector motion Weft replenishing motion

III- Auxiliary Motion

Terry motion Selvedge motion Weft petering motion Temples Brake

TYPES OF LOOMS

Hand Loom Power Loom

Shuttle Shuttle less

Non-automatic Automatic

Projectile Rapier

Air Jet

Water Jet

Weaving Department (Indigo Textile Mill)

During our internship in Indigo Textile Pvt. Ltd. we found that there are only Air Jet looms are installed.

In weaving dept., 98 looms, in which 95 looms are in production. The loom details are as under: Air jet delta Picanol 48 500RPM 70inchAir jet Tsudokama za205i 45 5000RPM 70inchAir jet Zex-e 50 8000RPM 70inch The average production per day is ~ 45000m at 48 avg. fills/picks.

Air Jet Looms Or Air Jet Weft Insertion System

This system is most improved form of weft insertion. In this system, the mechanism and machine parts have been totally eliminated used to drive the weft insertion source. This facilitate to increase the insertion rate up to 2500 ppm this type of machine is firstly commercialized by Swedish engineer Max Paabo in 1951. Weft thread is propelled using compressed air. It is simple operation with reduced mechanical parts and hence the maintenance cost is very low.

The working principles of air jet weaving machines are based on carrying the yarn by the friction of the air jet. During the yarn’s forward movement by the air in the sheds, the velocity of the weft yarn decreases because of the decreasing pressure and the disturbance on the air flow direction [3-5]. The air jet must provide a constant speed to the weft yarn along the weaving wideness. However, weft yarn of a certain mass is carried by a single jet at a limited distance. That is way the relay nozzles are installed at certain distance, in order to prevent a decrease in yarn velocity. The relay nozzle system and the general characteristics of the weft yarn speed in shed are show in figures 2 and 3 respectively. These are implemented on a movable hollow-needle or slay system. The basic function of the main jet is to load the nozzle at a certain speed. The weft yarn suddenly reaches high velocity by means of the main jet. To preserve weaving defects and asynchronous beat-up movement, the weft yarn position and the instant velocity of the weft yarn must be fully controlled during the weaving process. A schematic view of the air jet and its control system is shown in figures

Advantages of Air-Jet Weaving Machine:

High productivity High filling insertion system Reduced hazard because of new moving parts Low noise and vibration Low spare parts requirements To increase the production of loom by increasing the speed and by increasing the

width of loom Machines are versatile and roust to produces light to heavy value added fabric Almost all loom motions are being controlled electronically These looms can be operated up to 40 looms per operated Fully automatic lubrication system Produce 100% export quality goods

Role of controlled humidification in the reduction of yarn breakages

The effect of proper temperature and humidity conditions has long been recognized as an important factor in the processing of textile fibers, both cotton and the man made fibers. Since humidity has an effect on the strength of the fibers, quality and the rate at which processing may take place, its control is becoming increasingly important. With nearly all textile fibers being hydroscopic the amount of moisture present in an atmosphere to which they are exposed has a direct bearing on the moisture content of the fibers themselves. In understating the function of air conditioning and its effect on textile manufacturing, a review

of terms relating to temperature, humidity, and moisture content of fibers is necessary. Dry bulb temperature is that indicated by the ordinary room thermometer. Wet bulb temperature is the temperature to which air may be cooled by evaporating water into it with out change in the total heat and is indicated by the wet bulb temperature without changing dew-point. Adding moisture to the air at room temperature raises dew-point and lowers dry bulb temperature, giving a cooling effect. Relative humidity is the ratio between actual vapour density (or pressure) and the maximum which could exist at the same temperature to which air may be cooled without change in pressure of the contained water vapour. Any added attempt at cooling will only result in condensing of the moisture. Effective temperature is a measure of the feeling of warmth produce by a combination of temperature, humidity and air movement. A change of any one of those conditions will affect the relative humidity, changing the moisture content of the fiber. Moisture content, expressed as percentage of the total weight is the weight of the moisture expressed as percentage of the oven dry weight of the material. In specifying moisture content or regain, since most fibers contain some moisture in a natural state, it is not implied that the material has been completely drying by prescribed methods the allowing the sample to take up or regain its normal amount of moisture. Moisture content is generally measured in a laboratory where exact conditions are maintained, taking into consideration other factors, including conditions of the sample, twist, density of package, and length of exposure. Air conditioning which includes temperature and humidity control of conditioned air, functions as a production tool in maintaining desired conditions within the manufacturing area. Regulation of proper temperature and humidity in all departments eliminated many variables attributable to the influence of outside weather conditions. It also contributes to better efficiency of personnel and equipment. In determining the level at which temperature and humidity are to be maintained a combination of experience, recommendation of the manufacture of the man-made fiber type of manufacturing process, machinery used, and impact on operating personnel is considered. Conditionings are usually maintained at 80o dry bulb with the installation of complete air conditioning, including refrigeration until the relative humidity is 45% or below. It is generally agreed that with a lower humidity, a somewhat higher temperature is desirable owing to the effect on the operating machinery.

R.H= 98.6- (dry bulb temperature-wet bulb temperature) x Dry bulb temperature 300

Recommended relative Humidities Process Cotton Man-made fibers

Warping 55-70% 50-65%

Weaving 70-85% 55-70%

After determining temperatures and humidities for a given application consideration must be given to the type of system desired.

Advantage of controlled Humidification:-

Decreases expansion and contraction of shuttle, boxes, leathers and all hydroscopic parts

Improves texture and feel of cloth Holds cloth weights constant Diminishes warp shedding Increases strength of both filling and warp yarns Minimizes loom adjustment

WARPING MACHINE

(CREEL SECTION)

TYPES OF CREEL:-

Most common types of creels are

Parallel standard creel with fixed package frame. Parallel creel with package truck. Parallel creel with swiveling packages frame sections. Parallel creel with reverse package. Parallel creel with unrolling draw-off for polypropylene, monofilaments. V-Creel with reversible frame. V-Creel with reversible frames and automatic knotter. V-Creel with traveling packages.

Generally now a days parallel creel are used for section warping and direct warping system while the v-creel are used for the direct warping system.

In single creel, there is an only package for each warp end. Since creeling time is considerably high, the package size should be such that a manner of beam cans be from one creel. In this case more than one creel is used such that one a creel is exhausted and the next one would be readily available to continue to warping. Depending on the space available, this is done either by moving the head stock or by moving the creels.

In magazine creels usually two packages are used for each end. The tail end of running package is attached to the leading end of the reserve package. This allows spliced yarn the undesirable effects of the knots can avoided. In traveling package creel the creel is like a continuous belt. Usually tow creel form a V-Creel. When the full packages are used for the warping on the out side position, the empty or inner side can be filled by packages. When the full packages are empted the side with the full packages is brought to the warping area by the rotation and the warping is continued without much interruption except for threading of warp ends in the comb.

Advantages of V-Creel

No need of yarn guide. Uniform tension across the whole beam. Free yarn run from the creel to warping machine. Low tension on the yarn.

Essential Parts of Creel Section

Main frame consist of or hold the following parts.

Cone Holder Rod:-

Cone holder rods are used to hold the cone holders and the numbers of these rods are varying according to the desired packages.

Cone Holder:-

The cone holders are attached with the cone holder rods and these holders are used to carry the yarn packages. Usually these cone holders are eight in numbers.

Supply Package:-

Supply package is either cone or cheese from which contain yarn according to required length, weight and count. Each package are depending upon the requirement.

Guide Eye:-

Guide eye guide the yarn which is coming from the supply package.

Tensioners:-

It provides tension on yarn which is generally depending upon the count and quality of yarn.

Types of Tensioners

Following are the some of important types of tensioners

1- The post and disk tensioners. 2- The driven disk tensioners.3- Electronic tensioners.4- Spring loaded tensioners.

Basic purpose of tensioners in creel section is to provide the tension on yarn to avoid the slackness in warping beam. Commonly ion ball warping “THE POST AND DISK TENSIONER” is used because its use is very simple and cheap.The post and disk tensioners has been around for decades. As its name implies, this unit has two (some time three) post mounted on to a flat base. Two round dicks are placed onto each post. The yarn is threaded between the disk and warp around the posts. One of the post is moveable so that the angle of warp can be varied, thus applying different level of tension to the yarn (depending upon the angle of warp). Even more tension can be added to the yarn by the adding around weight on to the top disk, thus exerting more pressure on to the yarn between the disks. Advantages of the post and disk tensioners, it is very inexpensive, it dose a marginally adequate job for maintain yarn tension, it is simple to thread up and it has a fairly low maintance requirement. The disadvantages, the yarn has a tendency to jump out from between the disk at the near of creel, it is labors intensive when different tension level are required (weight have to added or removed on each tensioners in the creel), they have to cleaned often to prevent lint from building up between the disk and they don’t control tension well as higher speed.

Stop Motion:-

Basic purpose of stop motion is to stop the machine when the yarn breaks.

A stop motion device of some sort is also required in order to prevent a broken end from getting lost in the rope. There are several of these devices available.Types of stop motion are given bellow1- The drop wire system.2- Photo electric system.3- Electronic motion sensor.

During our intern ship in “Naveena Exporter Pvt ltd” and in “Indigo Textile Pvt Ltd” drop wire stop motions are being used.

This is simplest type available it works like this,

A drop wire is placed on to each yarn end in creel. Normally, this drop wire system is located on each vertical row at the front of creel bank. Beneath the drop wire is exposed to electric contact bar which in normally operation maintains and open electric circuit to the warped. When an end breaks, the drop wire falls on the contact bar an essentially, shot out the circuit. The reaction and response time for this system is very inexpensive, it is fact reacting, it can be used with many types of yarn and is easy to thread up. The disadvantages, it is common to have the expose the contact bar get covered with lint, fish and dust. When an end breaks, the drop wire will not make a solid contact with the bar and the system remains open. Also, if the end should break at or near the warper, these may be enough residual tension on the yarn, holding it up and preventing the drop wire from failing. Finally, not all size of yarn can be processed with the same weight of drop wire.

Revolving Fan:-

It is used to remove the suspended fibers of fluff from creeling section.

FINISHING

INTRODUTION:-

Textile finishing is a term commonly applied to different processes that the textile materials under go after pretreatments, dyeing or printing for final embellishment to enhance their attractiveness and sale appeal as well as comfort and usefulness. The term has been used in the past for all the treatments that the fabrics may undergo after weaving and knitting but this significance is now conveyed with the phrase “Wet Processing”. The finishing treatments are basically meant to give the textile materials certain desirable properties like softness, luster, pleasant handle, drape, dimensional stability, crease recovery, anti static, non-slip, soil-release etc However these also include finishes that have to meet certain specific end uses such as water-repellency, flame-retardancy, mildew proofing etc, just to name a few common ones. In addition to these, some finishing processes that may not be considered as exactly as ethical are sometimes given to cover either the faults of the fabric or to give a feel of heavy density to an otherwise lightweight material. This is done by binding clays on the fabric with the help of adhesives like starches or polyvinyl acetate.

The types of finishes required and their methods of application depend upon the nature of the fibrous substrate and their arrangement in yarn or fabric. The properties of fibers such as swelling capacity, chemical reactivity, response to heat-treatment etc determine the type of the finish suitable for a particular product. The cotton fabrics, for example, are given crease-recovery or crease-shedding finish that is not always necessary for the wool fabrics. The woolen materials, on the other hand, require non-felting or machine washable finish and moth-proofing. The synthetic fabrics need heat-setting to stabilize their structure and soil-release treatments to make this acceptable to customers. Choice and degree of the finish and its equipment are further governed by factors such as structure of yarn, type of weave and construction of fabric i.e. whether woven, knitted, or non-woven.

FUNCTIONS OF THE FINISHINING PROCESSES

The main purpose of applying various finishes may be summarized as under.

1- HIGH SALES APPLAL: To impart properties of attractive appearance, supple handle, softness and good drape.

2- HIGH WEAR QULITY: This refers to adequate tensile and abrasion strengths, dimensional stability, crease recovery and freedom from pilling.

3- BODY PROTECTION AND COMFORT: This relates to proper heat insulation, moisture absorption and air permeability.

4- SPECIAL EFFECTS: These include water-repellency, reduced flammability, mildew and moth-proofing, anti-static behavior and soil release property.

FINISHING OF CELLULOSIC MATERIALS:-

Cellulosic fibers especially cotton is a robust textile material and has many attractive properties like pleasant handle, good moisture absorption, strength durability, and easy laundering. However it lacks luster of wool, silk and man-made fibers. It also has poor dimensional stability and unlike wool and synthetic fibers cannot be heat-set to stabilize its structure. Again, in contrast to the keratin and some synthetic fibers, cotton is deficient in chemical reactivity and is not very amenable to chemical modifications. In view of these shortcomings, cellulosic materials require some special physical and chemical finishes so as to make these more attractive and serviceable.

CLASSIFICATION OF FINISHES:-

Considering the existence of a large number and a great variety of the finishes for the cellulosic fibers, it is understandable that a completely satisfactory classification is not possible to make. The finishes are often sub-divided as physical and chemical, permanent and temporary, deposition and reactive etc. Sometimes the finishes are classified according to the effects obtained like appearance, wearing qualities, weighting etc. To complicate the matter further, the final folding and packing of the materials is sometime included in the list. However the following description, through not perfect, is fairly rational and does justice to the topic.

Physical/Mechanical Finishes:-

(a)TEMPORARY/NON PERMANENT

i). Calendaring: Swizzing, Friction, Chasing, Schreiner, Embossing and Felt

ii). Beetling

(b)DURABLE

i). Raising, Sueding, (Emerising or Peach Finish)

Chemical Finishes:-

(a)TEMPORARY/NON PERMANENT

i) For handle and Appearance: Softening, Stiffening, Weighting, Lustering (other than Mercerizing)

ii) Special Effects: Water-Repellency, Flame-Retardancy, Mildew proofing

(b)PERMANENT

i) Crease Recovery, Softeningii) Water-Repellency, Flame-Retardancy, Mildew-Proofing

FINISHING RANGE FOR DENIM

Singing

Washing/ Softener Application

Sanforizing

Batch Formation

Singing:-

Normally the denim singing is done at 110 to 120 degree for 30 second with a flame pressure of 10 to 12 bar.

Washing:-

In washing fabric is treated with a softener and wetting agent, commonly used softener is silligent and wetting agent is J.V. Due to wetting agent desizing is done.

Sanforizing:-

The term Sanforizing is used for shrinkage purpose.Comprehencesive shrinkage machines are used for Sanforizing purpose.

Finishing Department (Indigo Textile Mill)

In finishing dept. there are 2 finishing ranges having production capacity of 45000m per day. They have capacity to finish regular as well as flat. Machines #01 has 05 boxes and Machine #02 has only 2 boxes which is normally used for normal-regular finish…

Details are as under:

For flat Finish Function Volume pH

Causticization to improve absorbency 1800lit 13+ Hot Wash to reduce contamination 1800lit 9-11 from Fabric Acid Wash to neutralize the Fabric 1800lit 4-6Cold Wash to remove acidity from Fabric 1800lit 5-7Softener to soften 1500lit 6.5-7.5

In support there are 2 feeding tanks, for caustic and for Softener. Each has maximum volume of 1500lit. For acid feed there is a purging of acid dosage.

For Normal Finish Function Volume pH

Washing to wash out fabric with 1800lit 9-11 Detergent Softener to soften and neutralization 1500lit 6.5-7.5

On machine 32 De-sizing and Normal Finish is performed.

For De-Sizing Function Volume pH

De-Size to remove size form Fabric 1800lit 8-10Softener to soften and neutralization 1500lit 6.5-7.5

For Normal Finish Function Volume pH

Washing to wash out fabric with detergent 1800lit 8-10Softener to soften and neutralization 1500lit 6.5-7.5

Both machines are of course having J-tray, Brushing, Singing, Dips and dry canes, Rubber Belt (max. temp-90Co), Palmer and Batcher.

The chemical used in this dept. are as under:

Chemical Name Description Brand

Caustic Soda 50% Liquid for Flat Finish localMercerol QWLF for mercerization ClarientCMS-900 detergent localAlka soft 5200 paste non-ionic softener localAlkasoft HT-100 nano silicon softener localAlkazyime HSM concentrated de-sizer localFormic Acid for neutralization local

INSPECTION/FOLDING

I. The fabric made on loom is in roll form, there for to unwarp roll and then fold it again called folding.

II. In folding department firstly they inspect the fabric giving a certain grade, secondly they fold and finally dispatch as per required

III. During inspection different types of fault are caught which some of them re following

Double picks Miss pick End out Cone change Starting marks Wrong denting Broken end Double end Loose end Tight end Knot mark Oil spot Float Hole tears Balls Hard size Sizing stain Dyeing stain Miss dyeing Slub in weft Coarse pick Slub in warp Coarse end Count variation Loose weft

These are the faults that occur during production and are inspected in folding department on inspection machine.

CONCLUSION

In Pakistan, textile industry is back boon of the economy of the country. Its contribution to export trade is about 67%. Thus it has export potential; Pakistan has not yet tapped the market for denim as the industry of Pakistan has the capacity to manufacture world class (i.e. export quality) denim fabric & goods made from denim.

An analysis shows that the demand of denim goods is higher than the demand of other textile goods made from other fabrics. There is a large export market for denim. Our textile industry can capture large share of export market by exporting its export quality denim.

While doing this project we observed that there is an acute shortage of trained professionals & labors in the field of denim manufacturing.

In our opinion, at the present time most of the institution are focusing on imparting conventional textile processing know how of the manufacturing of denim. This problem needs to be addressed by revising the syllabuses of the institution; no institutions are well equipped to impart knowledge regarding denim manufacturing process.