Dyeing Techniques for Cotton and Its Blends

WHY BLENDING? The variety of natural and manmade fabrics available today, offers a wide selection of fibres for use. But all fabrics are not perfect in one way or other. They all have some good, fair and poor characteristics. Blending of cellulosic fibres with manmade fibres to produce fabrics with improved characteristics has long been accepted throughout the world. The price structure and multi fibre policy of government have increased the use of cellulosic blended fabrics. The properties of the fibres blended are combined and made into a modified state in blended fabric. If blending is done carefully the good qualities of the fibres are emphasized minimising the poor qualities. REASONS WHY FABRICS ARE BLENDED 1. The important reason for blending fibres is to produce better performance. By blending we can improve the characteristics that are poor in one fibre, by blending it with another type of fabrics that excel in those characteristics For example polyester when blended with cotton, the resultant fabric has moderate absorbency which is almost nil in polyester.

2. To improve the texture, hand or feel and appearance of fabrics Blending of wool fibres with polyester produces the desired texture for suiting materials. Viscose when blended with cotton improves it's lustre and softness and there by enhances it's appearance.

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3. To reduce the cost this is sometimes one of the important reasons for blending of fibres. The cost of a very expensive fabric can often be reduced by blending with another cheap fibre. For example expensive wool is blended with cheaper polyester to reduce the cost.

4. To produce cross dyed effects Fibres with unlike dye affinity are combined and dyed together so that it produce interesting cross dyes effects as one fibres take up the colour and the other retains its original colour.

5. To improve the spinning, weaving and finishing efficiency for example the spinning efficiency of polyester is improved by blending with cotton to produce spun yarns. Blending may be done before or during spinning. It can be done at the opening and blending stage. Though it facilitates perfect blending it poses problems and so it is not in much use. Even at the sliver stage over drawing or roving or spinning frames blending can be done. Blending over drawing frame is most commonly used today. Slivers of different fibres are combined over drawing frame depending on blend ratio. They are drawn to get a single silver which is later processed into yarn.

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PROBLEMS IN DYEING WITH BLENDS: Cotton being the natural fibre is easy to dye being hydrophilic in nature. This hydrophilic nature of cotton helps in dyeing with water soluble dyes like direct dyes, reactive dyes, sulphur dyes, vat dyes etc. But with hydrophobic fibres like polyester, nylon etc are not easy to dye with these water soluble dyes due to very less affinity towards dye molecule. These are dyed with forcefully inserted into fibre surface with mean of temperature, pressure. For the specific characteristics natural and manmade fibres are combined together or blended this makes the dyeing of the following composition much more typical emphasizing the feel and aesthetics of natural fibres and also not affecting the properties of manmade fibres too. Compatibility of dyes from different application categories with one another. Blended fiber or Blend textile requires particular and fiber specific dyes to be properly dyed. It is seen that; if you use usual dyestuff to make a blended fiber or blended fabic dyed, then some parts of that fabric has been dyed and some other parts haven’t been dyed.

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SELECTION OF DYES FOR DYEING OF DIFFERENT FIBRES:

Fibre’s name

Source

Commonly used dyes

Cotton

Seeds of cotton plants

Vat Dyes and Azonine Dyes (Direct Dyes)

Linen

Stalk of the flax plants Reactive Dyes

Hemp

Stems of the Cannibissativa plants

Fiber Reactive Dyes

Ramie

Bast of plant fibers

Vinyl Sulphone Fiber Reactive Dyes, Fiber Reactive Dyes

Jute

Stems of Jute plants

Vat Dyes

Source: http://dyes-pigments.standardcon.com/dyes-cellulose-fibers.html

Name of fibres

Name of common dyes that are used

Polyester

Disperse Dyes

Acetate (Cellulose acetate)

Doesn't take dyes ordinarily. It requires cross dyeing.

Acrylic

Disperse dyes

Modacrylic

Fiber Reactive Dyes

Modal

Fiber Reactive Dyes

Nylon

Cationic Dyes, Acid Dyes, Disperse Dyes

Orlon

Disperse Dye

Rayon

Acetate Rayon Dyes

Saron

RIT Dyes

Spandex

Disperse Dyes

Vinalon

Doesn't take Dyes (in normal condition)

Vinyon

Doesn't take Dyes (in normal condition) Source: http://dyes-pigments.standardcon.com/dyes-synthetic-fibers.html

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Cellulosic fibres are generally dyed in jigger machine or winch dyeing machine. These machines can be open or closed as required to maintain temperature and pressure. For the continuous dyeing of materials, usage of j-boxes, padding mangles and IR heating is common now a days. Cellulosic materials are generally obtained from natural resources and are hydrophilic in nature due to presence of oxygen molecule in cellulose molecular structure. On wetting of fabric with water, cellulose molecule produce anionic sites. These anionic sites help in building the bondages with dye molecule for beer stability. Dyes have affinity for both water as well as fabric this decides the rate of absorption of dye molecule in fibre structure.

Dyeing cellulose with direct dyes: Direct dyes are soluble in water and have substantive affinity to water and fabric too. These dye molecules are sodium salt of sulphoinic acid when dissolved in water produce anionic sites which have repulsion with fabric surface having negative sites on it too. These negative sites on fabric surface are reduced with the help of sodium chloride or glauber salt as exhausting agent. Direct dyes shows poor washing fastness and light fastness which can be improved inn after treatments with potassium dichromate and copper sulphate respectively.

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Dyeing cellulose with reactive dyes: Cellulosic materials have better affinity for reactive dyes. These dye molecules contain tri azine ring which help in attachment with cellulose molecule with help of covalent bond. This provide a stronger attachment which leads to better fastness properties. Dyeing is carried in presence of common salt and sodium carbonate. Reactive dyes react chemically with fibre cellulose molecule

Source: https://en.wikipedia.org/wiki/Reactive_dye

Steps of dyeing on cellulosic materials with reactive dyes: (1) The initial exhaustion phase. Dyeing is started in neutral solution so that there is little likelihood of the dye reacting with the cellulose. During this stage of dyeing, some reactive dye will be absorbed by the fibres, the amount depending upon its substantivity. Sodium chloride or sulphate will often be present initially or be added gradually to the dyebath during this phase to promote exhaustion. The temperature of the dyebath may also be gradually increased to aid penetration of dye into the fibres and to assist migration (2) The fixation phase. After the initial exhaustion phase, the pH of the dyebath is increased by complete or gradual 6

addition of the appropriate type and amount of alkali. This causes dissociation of some of the hydroxyl groups in the cellulose and the nucleophilic cellulosate ions begin to react with the dye. The fixation process then results in additional dye absorption, to re-establish the dyeing equilibrium. Dye absorption from solution and reaction with the fibre then progress until no further dye is taken up. (3) The post-dyeing washing. The rinsed dyeing contains dye bonded to the cellulose, absorbed but unreacted dye, as well as hydrolysed dye. There will also be residual alkali and salt. The latter are relatively easy to remove by successive rinsing in cold and then warm water. As much unfixed dye as possible must be washed out of the dyeing. If this is not done, desorption of this dye during washing by the consumer can cause staining of other materials in the wash. Some unfixed dye is eliminated during the initial rinsing that removes salt and alkali. Thorough washing of the dyeing using a boiling detergent solution (soaping) eliminates the remainder. The dyeing is then finally rinsed in warm water. Soaping must often be repeated for deep dyeings or the residual unfixed dye must be complexed with a cationic agent.

Dyeing cellulose with vat dyes: Vat dyes are water-insoluble pigments. They are called dyes because chemical reduction in alkaline solution converts the pigment into a water-soluble leuco form with substantivity for cotton. The vat pigment and the leuco compound often have quite different colours – blue and pale yellow in the case of Indigo – so the progress of the reduction is often easy to observe. After dyeing with the leuco compound, the pigment is regenerated in the dyed cotton by oxidation. The overall process therefore involves three key steps: (1) Reduction of the pigment to the soluble leuco compound, a process called vatting; (2) Absorption of the leuco compound by the cotton during dyeing; (3) Oxidation of the absorbed leuco compound in the cotton, reforming the insoluble pigment inside the fibres. 7

Source: https://image.slidesharecdn.com/vatdyes-160603174040/95/vatdyes-8638.jpg?cb=1464975744

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Dyeing of cotton/polyester blends: Commercially polyester/cotton blended fabrics are dyed by twobath or one-bath two-step dyeing method employing suitable dyes and chemicals for each fiber. Two bath dyeing methods are relatively long and complicated. The one-bath two-step dyeing procedure is shorter as compared to twobath method, but the drawbacks are lower dyeability and poor reproducibility. Dyeing of cotton by conventional reactive dyes is carried out under alkaline conditions at 80°C, but this is entirely different condition from that of polyester dyeing, which is carried out at acidic conditions over 120°C by using dispersed dyes. Many research works have been carried out to dye polyester/cotton blends in one-bath dyeing method using conventional dispersed dyes and newly developed reactive dyes which can be dyed at acidic or neutral conditions around 100–130°C and are added simultaneously to the same bath. One-bath method for dyeing of polyester/cotton blends with reactive disperse dyes using supercritical carbon dioxide as a solvent at 393 K and 20 MPa. the process of dyeing polyester/cotton fabrics using disperse/reactive dyestuff in onebath dyeing process after coating the fabric with chitin biopolymer and then dyed with sulphato ethyl sulphonyl disperse/reactive dyes. Exhaust dyeing method or batch dyeing methodThis is again classified in the following three groups1. Two bath dyeing 2. One bath one step dyeing 3. One bath two step dyeing method Thermosol Dyeing method It is again classified in to two groups1. Continuous dyeing2. Pad batch process (semi-continuous)

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EXHAUST DYEING: Two bath dyeing 1. This is the process in which we have to dyed first polyester part in the HTHP beam dyeing machine or HTHP jet dyeing machine and the cotton part is dyed in the jigger machine. 2. Batch process 3. Machine used for dyeing of polyester partHTHP Beam dyeing machine( First commercialized HTHP machine)  HTHP jet dyeing machine 3. Machine used for dyeing of cotton part- Jigger dyeing 

Source : https://www.slideshare.net/ashisdua/dyeing-of-polyester-and-cotton-blends

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PROCESS ROUTE P/C BLEND DYEING:

Source : https://www.slideshare.net/ashisdua/dyeing-of-polyester-and-cotton-blends

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One bath two step dyeingOne-bath dyeing processes, using both the dyes such as following in the same dye bath. 1. Disperse and vat dyes. 2. Disperse and reactive dyes. 3. Disperse and direct dyes.

DISPERSE/REACTIVE DYEING SYSTEM:

Source : https://www.slideshare.net/ashisdua/dyeing-of-polyester-and-cotton-blends

Disperse/vat dyeing system: Typical dyeing recipe     

Disperse dye-X% Vat dye-Y% Dispersing agent-.5-1% wetting agent-.5-1% pH 4-5 with acetic acid (30%) 12

Procedure Prepare the bath with dispersing agent, wetting agent and acetic acid + treatment for 10-15min at 50-60°c then + disperse and vat + dye for 10-15min + raise temp up to 130°c in 60-90 min. After PET part dyeing cool to 80c for proper levelling then add NaOH & Na2S2O 4 + dyeing 15min + cooling to 60°c + dyeing for 30 min. for better exhaustion Rinse with cold water + oxidation with H2O2 for 15min at 50°c + Rinsing with cold water + Soap at 95° C for 25 min using 2 g/l Lissapol D + Hot and cold rinse and then final wash off. Only vat dyes (Ik vat dyes) which are stable up to 130°c can be used for this process. One bath two step dyeing methodAll vat dyes may be used for the one –bath high temperature process provided that the dyes are finely divided enough. The IK vat dyes are not preferred because the dye liquor requires to be cooled to about 30°c in order to obtain full colour yield. Therefore when IK dyes are to be used it is preferable to dye by the twobath process. Typical dyeing recipe Disperse dye-X%  Vat dye-Y%  Dispersing agent-0.5-1%  Wetting agent-0.5-1%  Ph 4-5 (attained with 1-2 ml/l of 30% acetic acid) Oxidation and soaping: Oxidation and soaping can be achieved simultaneously using the following recipe:   

Hydrogen peroxide(35%) 1-2 ml Anionic detergent -.5-1g/l Ph-9-10

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First treat the material for 10-15 min. at 50°c with hydrogen peroxide. Then the anionic detergent and raise the temperature to 95°c. Soap for 10-15 min.   

Method is used when selected vat dyes severely. It stain PET component during high temp dyeing. Vat dye is added at 80°c after PET part dyeing rather than adding at the start with disperse dye. Except it the whole process is same as the dyeing in one bath one step.

DISPERSE/REACTIVE SYSTEM Same as one step dyeing except the addition of reactive dye at 80°c. This process is used for the reactive dyes which are not stable up to 130°c, due to which they cannot be used in one step process. Thermosol Dyeing method:  Continuous dyeing.  Pad batch process. Advantages of Thermosol dyeing       

Continuous process so it gives higher production. Dye utilization is excellent. Dye can be used afterward. No carrier is required. Fabric is processed in open width form so natural feel of fabric do not get disturbed. No crease formation. Lower energy is required than batch. No extra heat setting is required

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Disperse/vat dye system- PDPS method (Continious method)

Source : http://textilelearner.blogspot.com/2013/06/dyeing-of-polyester-and-cottonblend.html

ONE BATH ONE STEP THERMOSOL DYEING WITH DISPERSE AND REACTIVE DYES:

Source : http://2.bp.blogspot.com/owOsdEtpysQ/UcVDhX3V2tI/AAAAAAAAH3k/jAwOciC71ZE/s1600/Untvitled.jpg

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CHEMICAL RECIPE & PROCEDURE: Chemical recipe     

Disperse dye-x g/l Reactive dye-y g/l Sodium bicarbonate or soda ash-5-20g/l Urea-100-200g/l Migration inhibitor-10-20 g/l Wetting agent- 1-2g/l

PROCESS-pad-dry-thermosol-cool-wash: 1. PADDING  Padding Temp-20-300 c  Liquor pick up-60-80% 2. DRYING  First partial drying in infrared pre dryer and then fully drying.  Partial drying is done to avoid migration of dyes.  Drying is done at 120°c. 3. THERMOFIXATION  It is done at 180-220°c, 30-45sec  It is the fixation step. 4. PADDING  Padding bath contain NaOH + Na2S2O4 5. STEAMING  During this vat dye penetrated inside the cotton part. Then oxidation, soaping and finally washing. One bath one step dyeing process-Disperse/Reactive dyes:    

Padding in the second step is done using NaCl + NaOH H- Brand reactive dye is used. Fixation is done during steaming with saturated steam (102°c) for 30-60 sec. Then washing, soaping and again washing.

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Recipe Disperse dye-x g/l  Reactive dye-yg/l  Sodium bicarbonate or soda ash-5-20g/l  Urea-100-200g/l  Migration inhibitor-10-20 g/l  Wetting agent- 1-2g/l.

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   

Dyeing with Reactive Disperse Dyes in Supercritical carbon oxide. Dyeing of 80/20 PET/COTTON blend by using azeotropic solvent. Polyester/cotton blend fabric with sulphatoethyl sulphone disperse /reactive dye treatment. One-bath dyeing PET/COTTON blend with azohydroxypyridone disperse dye containing a fuluorosulfonyl.

Dyeing with Reactive Disperse Dyes in Supercritical carbon oxide: What is supercritical CO2 ?  

 

It is a naturally occurring that is chemically inert, physiologically compatible, and relatively inexpensive. It is nonflammable, it is supplied either from combustion process or volcanic process without the need of producing new gas & it is recycled in a closed system. No disposal problem. Easy to handle.

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Source : http://www.tst.tw/en/technology-more.php?Key=1

Source : http://tamulabo.w3.kanazawa-u.ac.jp/english/index.html

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Hydrophobicity of CO2 is useful in dyeing of polyester fibre or fabrics with disperse dyes as disperse dyes are also hydrophobic in nature and can dissolve in super critical CO2 and can easily penetrate in polyester fibre or fabrics.    

SC- CO2 act as a solvent in the range of 353-393°k temp, and 10-20 M Pa pressure For dyeing hydrophilic fibres like nylon, cotton- disperse dyes are not suitable for SC- CO2 dyeing. Cotton can be dyed with fluoro triaziynyl disperse reactive dyes at 120°c in SC-. CO2 For efficient dyeing in SC- CO2P/C blend fabric is immersed in the aqueous solution including 10% NMP ( N-methyl-2pyrrolidinone) which act as a solvent for pretreatment .

Pre-treatment1. 1% Na2CO3 + 10% NMP at room temperature for one hour + squeeze and dry at 373°K. 2. When dyeing with this dye small amount of hydrogen fluoride may be formed In the reaction but Na2CO3 present in the bath does not allow hydrogen fluoride corrosion. 3. This HF from dyeing solution is passed to the calcium hydroxide and recovered as calcium fluoride which is stable and harmless and present in the nature in fluorite form. 4. If the same dye is uses in thermosol dyeing than5. Homogenious dyeing is achieved in the SC-CO2 method compare to thermosol dyeing. 6. L/F was better in SC-CO2 7. In thermosol dye is sublime or dissolved by heating and penetrated in the fibres so the fibre is selectively dyed while in SC-CO2 dye is dissolved in the CO2 which is dissolve in the swollen fibre.

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CONVENTIONAL DYEING

DYEING IN SUPERCRITICAL CO2

High volumes of waste water with the residual dye chemicals, etc.

No waste water at all. Dye remains as powder. No need for dispersing, leveling agents

High-energy requirements

Only 20% energy requirement

Dyeing/washing, drying times is 3-4 hrs per batch.

Only 2 hours.

DYEING OF 80/20 PET/ COTTON BLEND BY USING AZEOTROPIC SOLVENT: The blended fabric is pre-treated with the azeotropic solvent. This solvent is directly apply with pad-squeeze-dry technique.

Source : http://textilelearner.blogspot.in/2013/06/dyeing-of-polyester-and-cottonblend.html

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DYEING RECIPE:         

Disperse dye-2% Reactive dye-2% Glauber’s salt-5 gpl Soda ash-3 gpl Borax-5gpl Ph-10 to 11 MLR-1:50 Temp-80,95,1100c Time-30,45,60 min.

SULPHONYL DISPERSE/REACTIVE DYES TREATMENT BY CHITIN –BIOPOLYMERS:    

Pre-treated the fabric NAOH solution. The washing & rubbing fastness properties improved. The dyed sample show good rubbing within the range of colour. The colour strength of the dyed sample of the dyed sample increased with increase deposition of chitin on fabric.

DYEING:

Source : http://textilelearner.blogspot.in/2013/06/dyeing-of-polyester-and-cottonblend.html

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Dyeing with Azohydroxypyridone Disperse dyes containing a fluorosulfonyl group- Advantages:   

  

It is a one-bath dyeing of PET/ cotton blends . alkali-clearable azohydroxypyridone disperse dyes. alkali-clearable azohydroxypyridone disperse dyes .containing the fluorosulfonyl group under hightemperature dyeing conditions is feasible. Better fastnesss properties. These dyes saves a lot of chemical energy. Excellent levelness properties.

DYEING:

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1. One bath dyeing of Polyester/cotton blend fabrics with reactive disperse dyes in successful with SC-CO2 .The optimum dyeing temperature and pressure are about 393 K and 20 Mpa respectively . The dyeing behavior of Polyester/cotton blends is strongly affected by the dyeing characteristics of the cotton side.The colour fastness of dyed fabric is almost satisfactory ,but colour fastness become weak with a decrease in the dyeing temperature. In addition ,the colour fastness of fabric dyed in SC-CO2 is better than that with that the thermosol dyeing. 2. Treatment with chitin pretreatment give the good dry rubbing and washing fastness . The alkaline pretreatment affects the greater adhesion of chitin to the surface of polyester fibres, which is manifested by the greater colour strength .Pretreatment in an alkaline solution containing 10 g/l NAOH is permitted .The greater amount of chitin used ,the worse affects are observed . 3. The same effect is observed in case of azeeotropic mixture on the dyeing behaviour of 80/20 cotton blends .As the pretreatment time increased dye uptake was found increase . The slight improvement in fastness properties was also found. 4. Dyeing of PET/COTTON blend with disperse dye containing the fluorosulfonyl group under high temp. dyeing conditions are feasible .Its decrease our labour cost, chemicals, energy.

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HTHP beam dyeing machineAdvantages & features: 1. Loading and unloading of the fabric is easy and time of dyeing is short. 2. Dyeing in open width form. 3. Most suitable for those fabrics that might crease, extend or abrade when dyed in machines where the fabric is in motion. 4. Not appropriate for compact fabrics 5. De-aeration is essential to avoid paler dyed spots. 6. A wetting agent helps to eliminate air bubbles within the fabric roll. Recipe used HTHP dyeing:       

Disperse dye- X%(depends upon the shade) Dispersing agent-1g/l Sequestering agent-1-2g/l(If required) Defoamers -.5 to 1g/l Levelling agent-.5 to 1 g/l Wetting agent- .5g/l Acetic acid-enough to get Ph=5-6

Flow of the liquor usually in the in-to-out direction, but it can be reversed. Out-to-in flow can compress the material causing flattening and glazing, particularly on the inner layers.    

Material stationary and liquor is moving. Batching is very important, during batching tension should be uniform and optimum. M:Lratio is 1:10 Both cloth and yarn can be dyed on this machine

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HTHP BEAM DYEING MACHINE:

Sectional diagram of a high-temperature beam dyeing machine Disadvantages of beam dyeing machine:   

Fabric of different width can not be dyed together on a single beam. The dyed fabric may be display moiré effect if it is tightly due to shrinkage. Uneven dyeing may occur if the beam is fully loaded ,as the dye liquor has penetrate several layers of fabric.

JET DYEING MACHINE:

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HTHP jet dyeing machine: The jet dyeing machine is an extension of the HPHT winch dyeing machine. Jet dyeing machine developed by BURLINGTON Industries and first machine developed in 1963 by Gaston country Machine co. of U.S.A Features:    

Both material and liquor is moving. Dyeing in rope form. Fabric speed usually 200-250mt/min The jet dyeing can usually operated up to 1400c under high pressure and having capacity capable of dyeing 100 to 150 kg of fabric at a time

Chemicals added      

Acids Buffers Sequestering agent Anticrease agent Defoamers Levelling agent

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Advantages of jet dyeing machine: 1. Fabric of two different width can be dyed at a time so that two lots can be combined together for dyeing. 2. No special batching device is required for winding the fabric as in beam dyeing. 3. There is no flattening effect or uneven dyeing on the fabric as in beam dyeing Disadvantages: 1. There is possibility of entanglement of light-weight fabric during dyeing. 2. Loose fibres removed from the fabric may get redeposited on the fabric surface as well as on the interior of the jet dyeing vessel, this problem does not arise in beam dyeing. 3. Yarn can not be dyed in a jet dyeing machine whereas it can be dyed in a beam dyeing machine. PROBLEMS1. Foaming problem 2. Oligomers problem 3. Rope marks

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WINCH DYEING MACHINE: A dyeing machine consisting essentially of a dye vessel fitted with a driven winch (usually above the liquor level) which rotates and draws a length of fabric, normally joined end to end, through the liquor. Winch dyeing machine is a rather old dyeing machine for fabrics in rope form with stationary liquor and moving material. The machine operates at a maximum temperature of 95-98°C. The liquor ratio is generally quite high (1:20-1:40). Winch dyeing machines are a low cost design that is simple to operate and maintain, yet versatile in application proving invaluable for preparation, washing or after treatments as well as the dyeing stage itself. In all winch dyeing machines a series of fabric ropes of equal length are immersed in the dye bath but part of each rope is taken over two reels or the winch itself. The rope of fabric is circulated through the dye bath being hauled up and over the winch throughout the course of the dyeing operation. Dyestuff and auxiliaries may be dosed manually or automatically in accordance with the recipe method.

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Description and Dyeing Method on Winch Dyeing Machine: The basic principle of all winch dyeing machines is to have a number of loops or ropes of the fabric in the dye bath, these ropes are of equal length, which are mostly immersed in the liquor in the bath. The upper part of each rope runs over two reels which are mounted over dye bath. At the front of the machine, above the top of the dye liquor, is a smaller reel, which is called jockey or fly roller. The fly roller remain free wheeling along with fabric rope. At the back of winch tank is the winch wheel, which pulls the fabric rope from the dye bath over the jockey reel for dropping in the dye bath for immersion. From the dropped location, the fabric rope travels back. to be lifted and fed to winch wheel. The dyeing process on winch dyeing machines is based on higher M:L as compared with other dyeing machines. The process is conducted with very little tension . The total dyeing time is lengthier as compared to other machines. 30

Advantages of Winch Dyeing Machine : 1. Construction and operation of winch are very simple. 2. The winch dyeing machines are suitable for types of wet processing operations from desizing to softening. 3. The winch dyeing machine is suitable for practically all types of fabrics, which can withstand creasing in rope form processing. 4. The tension exerted on winch is less than machine, the material thus dyed is with fuller hand. 5. The appearance of the dyed goods is clean and smooth on winch dyeing machines.

Limitations of Winch Dyeing Machine : 1. Batch dyeing operations needs trimming, sewing, and opening out the rope, loading and unloading for individual lots separately. 2. Since several lengths of fabric are run over the winch reel into the liquor and sewn end to end, Continuous length processing is not possible in a single batch. 3. Fabric is processed in rope form which may lead to crease marks, particularly in heavy, woven, thin and light synthetics. 4. Most of the machine work under atmospheric conditions

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JIGGER DYEING MACHINE: Jigg or jigger dyeing machine is one of the oldest dyeing machine used for cloth dyeing operations. Jigger machine is suitable for dyeing of woven fabrics, up to boiling temperature without any creasing. Jigs exert considerable lengthwise tension on the fabric and are more suitable for the dyeing of woven than knitted fabrics. Since the fabric is handled in open-width, a jig is very suitable for fabrics which crease when dyed in rope form.

Source : http://textilelearner.blogspot.in/2011/03/working-process-of-jiggerdyeing_5465.html

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Dyeing Process by Jigger Dyeing Machine:

Source : http://textilelearner.blogspot.in/2011/03/working-process-of-jiggerdyeing_5465.html

The dyeing process on jigger is regarded as a series of intermittent padding operation followed by dwelling periods on the main roller, during which the dyeing action and diffusion takes place. The factors controlling the rate of dye absorption are: 1. The amount of interstitial dye liquor retained in the interstices of the fabric weave. 2. The exhaustion of the interstitial liquor in the dwell period between successive immersions. 3. The degree of interchange of liquor during one immersion (interchange factor). In the dyeing on jigger machines the cloth revolves on two main rollers, The open-width fabric passes from one roller through the 33

dyebath at the bottom of the machine and then onto a driven takeup roller on the other side. When all the fabric has passed through the bath, the direction is reversed. Each passage is called an end. Dyeing always involves an even number of ends. The dye bath has one or more guide rollers, around which the cloth travels, and during this immersion achieves the desired contact with the dye liquor. During this passage the fabric picks up adequate quantity of dye liquor, excess of which is drained out but still a good quantity is held in the fabric. During rotation of rollers this dye penetrates and diffuse into the fabric. The real dyeing takes place not in the dye liquor but when the cloth is on the rollers, since only a very small length of fabric is in the dyebath and major part is on the rollers. Therefore the speed of cloth during immersion in dye liquor has a very little effect on percentage of shade produced. Some critical problems related to the conventional jigger dyeing machines (which are minimized in the modern day machines) The major problems are side-to-centre color variations, called listing, and lengthways color variations, called ending. Other problems are 

Temperature control from side-to-side and end-to-end of the roll



Tension control from end-to-end



Constant speed control from end-to-end



Prevention of creases



Prevention of air

Limitations of Jigger Dyeing 1. Jigs exert considerable lengthwise tension on the fabric and are more suitable for the dyeing of woven than knitted fabrics. 2. In textile preparation due to the swelling and dissolution of size, which makes the fabric slippery and unstable in roll form. 3. The low liquor ratio makes washing-off difficult. 34

4. There is little mechanical action in a jig machine and it is less suitable where vigorous scouring is required before dying. 5. Moiré effects or water marks may arise on some acetate and nylon fabrics because of pressure flattening the structure of the rolled fabric.

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REFERENCES 1. Technology of dyeing , V.A. SHENAI (VOL-4) 2. Basic Principles of Textile Coloration by Arthur D Broadbent -Professor, Université de Sherbrooke, Département de génie chimique, Faculté de génie, Sherbrooke, QC, J1K 2R1, Canada

3. Dyeing of polester/cotton blends by R.B.Chavan Department of textile technology IIT Delhi 4. Chemical processing of textiles-1,NCUTE

5. http://textilelearner.blogspot.in 6. http://textilelearner.blogspot.in/2015/12/types-ofdyeing-machine.html

7. https://www.slideshare.net

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