Disperse Dyes: Properties, Classification, Dyeing and Printing Method

Introduction
Dyes are colored, unsaturated organic chemical compounds capable of giving colour to a substrate (a textile), i.e. colouring or dyeing it.

The term “disperse dye” have been applied to the organic colouring substances which are free from ionizing groups, are of low water solubility and are suitable for dyeing hydrophobic fibres. The dye has derived its name for its insoluble aqueous properties and the need to apply it from an aqueous dispersion. Of all the dyes, they are of the smallest molecular size.

disperse dyes

Disperse dyes have substantivity for one or more hydrophobic fibres e.g. cellulose acetate, nylon, polyester, acrylic and other synthetic fibres.

The negative charge on the surface of hydrophobic fibres like polyester can not be reduced by any means, so non-ionic dyes like disperse dyes are used which are not influenced by that surface charge.

History
In 1922, Green and Saunders made one type of coloured azo compound, in which a solubilizing group (for example- methyl sulphate, -CH2-SO3H) is attached to amino group. In dye bath, they are slowly hydrolyzed and produce azo compound and formaldehyde bi sulphate. This free azo compound was capable of dyeing cellulose acetate fibres. This dye was named “ionamine”. But this ion amine did not give satisfactory result in dyeing.

Later in 1924, Baddiley and Ellis produced sulpho ricinoleic acid (SRA) for dyeing acetate fibres. This SRA was used as dispersing agent. Later it was seen that SRA was capable of dyeing Nylon, polyester, acrylic etc. In 1953 this dye was named as “Disperse Dye”.

Properties of Disperse Dyes

  1. Disperse dyes are nonionic dyes. So they are free from ionizing group.
  2. They are ready made dyes and are insoluble in water or have very low water solubility.
  3. They are organic colouring substances which are suitable for dyeing hydrophobic fibres.
  4. Disperse dyes are used for dyeing man made cellulose ester and synthetic fibres specially acetate and polyester fibres and sometimes nylon and acrylic fibres.
  5. Carrier or dispersing agents are required for dyeing with disperse dyes.
  6. Disperse dyes have fair to good light fastness with rating about 4-5.
  7. The wash fastness of these dyes is moderate to good with rating about 3-4.
  8. Of all dyestuffs disperse dyes are of smallest molecular size.
  9. Generally disperse dyes are derivatives of azo, anthroquinone, nitro and quinine groups.
  10. They do not undergo any chemical change during dyeing.
  11. In presence of nitrous oxide, textile materials dyed with certain blue and violet disperse dyes with an anthraquinone structure will fade. This is called gas fading of disperse dyes which is a defect of this dye.

Classification of Disperse Dyes

A. According to Chemical Structure:
According to chemical structure there are following types of disperse dyes:

  • Nitro Dyes
  • Amino Ketone dyes
  • Anthraquinonoid dyes
  • Mono azo dyes
  • Di- azo dyes

B. According to Fastness Property:
According to fastness property there are following 4 types of disperse dyes:

  • Group A: These dyes have excellent dyeing properties and good fastness properties.
  • Group B: These dyes are excellent in high temperature and for carrier dyeing with moderate fastness.
  • Group C: These dyes are moderate for carrier and high temperature dyeing with higher fastness property than group B dyes.
  • Group D: These dyes are of excellent fastness to heat but for dyeing properties on carrier method.

C. According to Energy Requirement:
According to energy required for dyeing there are following 3 types of disperse dyes:

  • Low energy dyes: These dyes are used to dye with carrier. For dyeing 77°C temperature is required. They have extremely poor resistance to sublimation.
  • Medium energy dyes: These dyes are used to dye mostly in between temperature 104°C-110°C which provides better sublimation fastness than that of low energy dyes.
  • High energy dyes: These dyes are used to dye at temperature above 129°C and are suitable for continuous dyeing. They provide all round fastness properties.

Chemical Groups in Disperse Dyes
The percentage of chemical groups present in disperse dyes are as below:

  • Mono azo dyes:                       50%
  • Anthraquinonoid dyes:           25%
  • Diazo dyes:                              10%
  • Methyne dyes:                         03%
  • Styryl dyes:                              03%
  • Acrylene benzimidazol:          03%
  • Quinonaphthalon dyes:          03%
  • Amino naphthyl amide:          01%
  • Napthoquinone imine:            01%
  • Nitro disperse dyes:                01%

Commercial Names of Disperse Dyes

Name of dye Manufacturer Origin
Foron Sandoz Switzerland
Terasil Ciba-Geigy Switzerland
Dispersol ICI UK
Samaron Hoechst Germany
SRA British Celanese Ltd. UK
Setile ACNA Italy

Application Methods of Disperse Dyes

  • Method N: Normal dyeing method. Dyeing temperature is 80-100°C.
  • Normal NC method: Method of dyeing at normal temperature with carriers. Dyeing temperature 80-100°C.
  • Method HT: High temperature dyeing method. Dyeing temperature 105-140°C.
  • Method T: Thermosol dyeing method. Dyeing temperature 180-220°C, continuous method of dyeing.
  • Pad roll method: Semi continuous dyeing method.
  • Pad steam method: Continuous dyeing method.

Factors Considered for Selection of a Method

  1. Availability of dyeing machine.
  2. Required colour effect (dark/medium/light).
  3. Required colour fastness.
  4. Type of material to be dyed.
  5. Cost of dye, chemicals and auxiliaries.
  6. Overall economy of the system.
  7. Dyeing temperature.

Dyeing Mechanism of Disperse Dye
The dyeing of hydrophobic fibres like polyester fibres with disperse dyes may be considered as a process of dye transfer from liquid solvent (water) to a solid organic solvent (fibre).

Disperse dyes are added to water with a surface active agent to form an aqueous dispersion. The insolubility of disperse dyes enables them to leave the dye liquor as they are more substantive to the organic fibre than to the inorganic dye liquor. The application of heat to the dye liquor increases the energy of dye molecules and accelerates the dyeing of textile fibres.

Dyeing Mechanism of Disperse Dye

Heating of dye liquor swells the fibre to some extent and assists the dye to penetrate the fibre polymer system. Thus the dye molecule takes its place in the amorphous regions of the fibre. Once taking place within the fibre polymer system, the dye molecules are held by hydrogen bonds and Van Der Waals’ force.

The dyeing is considered to take place in the following simultaneous steps:

  1. Diffusion of dye in solid phase into water by breaking up into individual molecules. This diffusion depends on dispersibility and solubility of dyestuff and is aided by the presence of dispersing agents and increasing temperature.
  2. Adsorption of the dissolved dye from the solution onto the fibre surface. This dyestuff adsorption by fibre surface is influenced by the solubility of the dye in the dye bath and that in the fibre.
  3. Diffusion of the adsorbed dye from the fibre surface into the interior of the fibre substance towards the centre. In normal condition, the adsorption rate is always higher than the diffusion rate. And this is the governing step of dyeing.

When equilibrium dyeing is reached, the following equilibria are also established:

  1. Dye dispersed in the bath              ↔             Dye dissolved in the bath
  2. Dye dissolved in the bath               ↔             Dye adsorbed on the fibre
  3. Dye adsorbed on the fibre              ↔             Dye diffused in the fibre

Dispersing Agent
Disperse dyes are insoluble in water and form aqueous dispersion in water. At first these dye molecules are formed as large particles and they are made smaller particles by grinding. But as they are water insoluble, they will give uneven dyeing if they are directly used in dye bath. So to ensure uniform and trouble free dyeing the dye should be present in dye bath in an uniform and very fine form and should give an stable dispersion. This is the reason for which a special chemical is used in dye bath named dispersing agent. They should be effective under dyeing conditions, stable to hard water, high temperature and other dyeing assistants.

For example, soap powder, Turkey Red oil, alkali sulphates, alkyl aryl sulphonates etc. are some surface active agents which are recommended as dispersing agents in disperse dyeing.

Functions of Dispersing Agent

  1. It assists in the process of particle size reduction of dye.
  2. It enables the dye to be formed in powder form.
  3. It facilitates the recon version of the powder into a dispersion which is required for dyeing.
  4. It maintains the dispersion in a fine form in the dye bath through out the process.
  5. It increases the solubility of disperse dyes in water.
  6. It affects on the art of dyeing.

Effect of Various Conditions on Disperse Dyeing

Effect of Temperature:
In case of dyeing with disperse dye, temperature plays an important role. For the swelling of fibre, temperature above 100°C is required if high temperature dyeing method is applied. Again in case of carrier dyeing method, this swelling occurs at 85-90°C. In case of thermosol dyeing method, if temperature is kept more, fabric is kept for less time in thermosol unit. Because in higher temperature, less time is enough for thermo fixation of dye. If it is kept for more time, then dye sublimation and loss of fabric strength may occur. Again though disperse dye is a water insoluble dye, its solubility increases with increasing temperature.

Effect of pH:
For disperse dyeing the dye bath should be acidic and pH should be in between 4.5-5.5. For maintaining this pH, generally acetic acid is used. We may also use any mineral acid like H3PO4. But those are strong and costly. So mild acid like acetic acid is used for controlling pH of the bath. At this pH dye exhaustion is satisfactory. During colour development, correct pH should be maintained otherwise fastness will be inferior and colour will be unstable.

Heat Setting Procedure of Polyester Fabric
The process of heat setting is used to stabilize yarn twist, remove residual shrinkage, increase wrinkle resistance and obtain durable pleat. Polyester may shrink 7% at boil and even more at higher temperature.

The importance of heat setting is as below:

  1. To modify crystalline structure.
  2. To improve dimensional stability.
  3. To resist wet creasing during washing.
  4. To increase safe ironing temperature.
  5. To avoid shade variation.
  6. Affect water inhibition.

The disadvantages of heat setting are:

  • Some dyes sublime at high temperature.
  • Pre setting reduces dye uptake.

Heat setting can be done before or after dyeing. If the fabric is heat set before dyeing, the absorbency of fabric goes down and if it is done before scouring and bleaching then the dirt dust may permanently deposit on the fabric. If heat setting is done after dyeing then some dye may sublime at high temperature and thus cause shade variation.

The time of heat setting depends on the fabric state i.e. grey, scoured, bleached etc. It also depends on count of yarn in fabric. For heat setting hot air, hot roller or radiant machine can be used.

Reduction Cleaning
In case of dark shade dyeing, we have to use more amounts of dye and chemicals. But these chemicals should be removed from fabric after dyeing. For this reason, a special process is used in case of disperse dyeing. This cleaning process is called reduction cleaning.

A typical recipe for reduction cleaning is given below:

  • 1 gm/lit:                        Tingal W
  • 2 gm/lit:                        Hydrosulphite
  • 2-3 ml/lit:                     NaOH (56.5° Tw)

By reduction cleaning, surface dye molecules or unfixed dye molecules are stripped and this in turn results in level dyeing. Reduction cleaning also improves wash fastness property of textile material.

CARRIER DYEING METHOD

Carriers
It has been established that certain hydrocarbons, phenols, amino acids, amides, alcohols, esters, ketones, nitriles etc. accelerate the rate of dyeing polyester fibre with disperse dyes from aqueous medium at temperature up to 100°C. These dyeing assistants alter the dispersing properties of the dyes and the physical characteristics of the fibre so that more dye can be transferred from the dye bath to the fibre. These are called carriers and are necessary for dyeing polyester fibres at the normal pressure and temperature below 100°C to increase the dyeing rate and to permit dye migration within the fibre. Level dyeing of disperse dyes depend on the migration power of the dye which is affected by nature and amount of carrier, dyeing time, temperature and the shade.

Some Commercial Carriers

Commercial Name Manufacturer Chemical Class
Solvent OP Franco O-phenyl phenol
Tumescal D ICI Diphenyl
Palanil Carrier A BASF Aromatic Ether
Carrier PDC TCC Emulsifiable solvents
Dilatin TCR Sandoz Chlorinated aromatic compound
Butyl oleate HAR Ester

Factors Considered for Selecting a Carrier

  1. High carrier efficiency.
  2. Availability at low cost.
  3. Little or no effect on light fastness of final dyeing.
  4. Absence of unpleasant odor.
  5. Non toxicity.
  6. No degradation or discolouration of fibre.
  7. Ease of removal after dyeing.
  8. High stability under dyeing conditions.
  9. Compatibility with dyestuffs.
  10. Ease of dispersion in the dye bath.
  11. Low volatility of the carrier including low volatility in the steam.
  12. Uniform absorption by the fibre.

Mechanism of Carrier Action
In carrier method of polyester dyeing, carrier is used. Carriers swell the fibre and ultimately cause relaxation. They may operate by opening up the internal fibre structure and allow the dye molecules to diffuse more rapidly. They act as molecular lubricants reducing inter-molecular forces operating in the fibre, thereby following the dye molecule to force its way in. Its action may be described as below:

  • It creates dye film on fibre surface.
  • Carrier takes dye inside the fibre from dye carrier association.
  • It increases the solubility of dye in the dye bath.
  • Carriers penetrate inside the fibre polymer chain and thereby reduce inter-chain attraction. Thus polymer chains become movable and so dye molecules may enter the polymer system of fibre.
  • It increases fibre swelling.
  • The absorbed carrier increases the rate of dye uptake by creating liquid co-fibre.
  • It increases the absorbency power of fibre.
  • It lubricates the thermally agitated fibre molecules.
  • 2-10 gm/lit carrier is used depending on material and liquor ratio and depth of shade.
  • The automatic portion of carrier is postulated to have Van Der Waal’s force and attraction for hydrophobic group of it attracts water.
  • With increasing molecular weight the carrier efficiency also increases up to a certain limit.

Dyeing of Polyester Fabric with Disperse Dye in Carrier Method
The extreme crystalline nature of polyester fibres creates problems in obtaining dark shades by conventional dyeing methods even at high temperature. The carriers are found to assist the disperse dyes to enter the polyester polymer, enabling dark shades to be produced. The carriers swell the polyester fibres, increase inter polymer space and let the dye molecules to enter the polymer system easily.

RECIPE:

  • Dye
    – For light shade<0.5%
    – For medium shade 0.5-1.5%
    – For deep shade>1.5%
  • Carrier (phenol)           : 3gm/lit
  • Acetic acid                  : 1gm/lit
  • Dispersing agent         : 2gm/lit
  • Salt (NH4)2SO4         : 1-2gm/lit
  • pH                               : 4-5.5
  • M:L                             : 1:10
  • Time                            : 60 min
  • Temperature                : 90°C

PROCEDURE:

  1. At first, a paste of dye and dispersing agent is prepared and then water is added to it.
  2. Dye bath is kept at 60°C temperature and all the chemicals along with the material are added to it. Then the bath is kept for 15 min without raising the temperature.
  3. pH of bath is controlled by acetic acid at 4-5.5.
  4. Now temperature of dye bath is raised to 90°C and at that temperature the bath is kept for 60 min.
  5. Then temperature is lowered to 60°C and resist and reduction cleaning is done if required. Reduction cleaning is done only to improve the wash fastness.
  6. Material is again rinsed well after reduction cleaning and then dried.
dyeing curve
Fig: Dyeing curve

Advantages of Carrier Dyeing

  1. In conventional dyeing method, the extremely crystalline polyester fibres can not be dyed in deep shade. But by using carrier we can get medium to dark shade in boiling temperature.
  2. Materials can be dyed with simple equipments at atmospheric pressure and temperature below 100°C.
  3. Moderate level dyeing of polyester fabric can be done.
  4. Some carriers reduce the staining of wool while dyeing polyester-wool blends.
  5. Rate of dyeing can be increased by using carriers.
  6. Can be dyed quickly by using carriers.
  7. Improves fastness properties of fabric except light fastness.

Disadvantages of Carrier Dyeing

  1. Carriers add to production cost of dyeing. Firstly, for dyeing it is used which is costly and secondly for its removal alkali is required.
  2. Carriers are unhygienic and toxic. It creates skin diseases.
  3. Some dyeing machines may create carrier spot.
  4. Carriers affect the light fastness property of dyed material. This effect may be reduced by treating the material with hot air for 30 min.
  5. Some carriers are dyed specific. They posses different efficiencies with different dyes; others have compatibility with certain dyes.

HIGH TEMPERATURE DYEING METHOD

Dyeing of Polyester Fabric in High Temp Dyeing Method
In high temperature dyeing method either material or liquor should circulate. Otherwise dye molecules will not penetrate inside the material. They will stay on surface only.

In this method, temperature is kept in between 105-140°C and pressure is kept from 0 to 170 kPa. This method is also known as pressure dyeing which is used for highly crystalline synthetic fibres and their blends. This technique causes the fibre to swell even more than which achieved at 100°C temperature. So that dye molecules penetrate the fibre polymer system. It eliminates the need of carriers.

RECIPE:

  • Dye                              : 3%
  • Dispersing agent        : 1gm/lit
  • Acetic acid                  : 1gm/lit
  • Time                            : 60 min
  • Temperature               : 130°C
  • pH                               : 4-5.5
  • M:L                             : 1:10

PROCEDURE:

  1. At first a paste of dye and dispersing agent is prepared and water is added to it.
  2. PH is controlled by adding acetic acid.
  3. This condition is kept for 15 minutes at temperature 60°C.
  4. Then the dye bath temperature is raised to 130°C and this temperature is maintained for 1 hour. Within this time, dye is diffused in dye bath, adsorbed by the fibre and thus required shade is obtained.
  5. The dye bath is cooled as early as possible after dyeing at 60°C.
  6. The fabric is hot rinsed and reduction cleaning is done if required.
  7. Then the fabric is finally rinsed and dried.
dyeing curve
Fig: Dyeing curve

Thermosol Dyeing Method

Dyeing of Polyester Fabric in Thermosol Dyeing Method
Thermosol method is continuous methods of dyeing with disperse dye. Here dyeing is performed at high temperature like 180-220°C in a close vessel. Here time of dyeing should be maintained very carefully to get required shade and to retain required fabric strength.

Sequence:
This dyeing process is developed by Du Pont Corporation in 1949. here at sufficient temperature the fibres are soften and their internal structure is opened, polymer macromolecules vibrates vigorously and dye molecules diffuse in in fibre. It requires only a few seconds to 1 min and temperature about 200-230°C. The sequence of operation is:

Pading—-→Drying—-→Thermo fixing—-→After treatment

Procedure:

  1. At first the fabric is padded with dye solution using above recipe in a three bowl padding mangle.
  2. Then the fabric is dried at 100°C temperature in dryer. For dyeing, infra red drying method is an ideal method by which water is evaporated from fabric in vapor form. This eliminates the migration of dye particles.
  3. Then the fabric is passed through thermasol unit where thermo fixing is done at about 205°C temp for 60-90 seconds depending on type of fibre, dye and depth of shade. In thermasol process about 75-90% dye is fixed on fabric.
  4. After thermo fixing the unfixed dyes are washed off along with thickener and other chemicals by warm water.
  5. Then soap wash or reduction cleaning is done if required. And finally the fabric is washed and dried.

Comparison among high temperature, carrier & Thermosol method

Carrier Method High Temperature Method Thermasol Method
Carrier is used, no thickener used Neither carrier nor thickener used thickener is used, no Carrier used
Not used now a days Used now Method is in use
Lower dyeing temp(800-1000C) Higher temp dyeing (1050-1400C) Very high dyeing temp(1800-2200C)
Production less More carefulness required Very much carefulness required
Costly as carrier is used Not costly Costly as special m/c used
Less bright shade More bright shade Very bright shade
Batch wise process Batch wise process Continuous Process
Toxic & unhygienic process Non-Toxic & hygienic process Non-Toxic & hygienic process
More Shrinkage Less Shrinkage Less Shrinkage
Less Production Less Production Higher production
Carrier Removal is difficult & alkali is used Not Applicable Not Applicable
No change in shade No change in shade Change in shade may occur due to sublimation

Printing with Disperse Dye

Introduction:
Disperse dyes are the most suitable dyes for printing polyester fabrics. Selected dyes with good steaming & thermofixation fastness are suitable for printing . The washing fastness of disperse dyes on polyester are much higher than acetate, triacetate or nylon Disperse dyes have a high degree of dispersibility and the disperse dyes marketed in liquid form are easy to make in to stock thickening without predispersing. The printing paste should contain a dispersing agent.

Thickener used in printing with disperse dyes:
Proper selection of thickener is important in printing polyester fabrics with disperse dyes. It depends on method of printing (i.e. – Roller printing, screen printing) and method of fixation of dye. The kind of fabric to be printed also influences the thickener choice. Suitable thickener should adhere well to the fabric and should produce an elastic film to prevent cracking. The thickener should be easily removal in the after treatments.

Thickening with a high solid content bring less water on hydrophobic fabric and produce sulpher and more level prints than those with low solid content. But the thickening with low solid content behave better with respect to cracking and in thermosol process for better colour yeild. But its sharpness in prints is not as good as with high solid contents thickenings.

The most commonly used thickeners used in printing with disperse dyes are mentioned below:

  1. Starch ethers (best)
  2. Natural Gums
  3. Locust Bean Gum
  4. Meyprogum
  5. CMC (car boxy methyl cellulose)

Printing on polyester fabrics with disperse dye:
For printing on polyester fabric with disperse dye the selection of thickener is very important. The print paste should adhere on the fabric surface and penetrate in to it. During fixation of the dye at high temperature, the fabric is in a paste state and the dye in a volatile state, so that it “dissolves” in the fabric & the colour becomes very fast. The penetration becomes so deep that it is difficult to distinguish between the printed fabric side & back side.

The fabric is printed with the following recipe:

  • 5 Parts             :           Na- Acetate
  • 20 Parts           :           Citric Acid / (NH4)2SO4
  • 100 Parts         :           Disperse Dye (liquid form)
  • 175 Parts         :           Water
  • 700 Parts         :           Myeprogum / Locust Bean Thickener.

––––––––––––––––––––––––––––––––––––––––––––––––––
……..1000 Parts

In the paste citric acid adjusts pH between 5.5-6 Na-Chlorate protects the brightness of prints & prevents reduction during steaming.

After printing the fabric is dried carefully & the dye is fixed by one of the following methods.

After thermo fixation of dye, the fabric is washed & reduction cleaning is then carried out. Reduction cleaning is carried out to obtain deep shades. (>5-15%).

Fixation Methods After Printing:
After printing with disperse dyes the dyes is fixed on the fabric by one of the following dye- fixation methods, namely-

  1. Thermo fixation
  2. Super Heated Steaming
  3. High Pressure Steaming

Now they are mentioned below:-

Thermofixation:
The features of this method of dye fixation are mentioned below:-

  • No steam is used.
  • Dye is fixed by subjecting the print to hot air at 2100C for 1 minute.
  • The fixation is carried out in a backing oven or in a stenter where heat setting can also be done simultaneously.
  • The process productivity is high.
  • The dye which have good sublimation fastness are subjected to this thermofixation process.
  • There is 10-15% loss of colour in thermofixation, so the shade becomes dull.
  • It is a continuous process of dye fixation which gives high production.

Super Heated Steaming:
The features of this method of dye fixation are mentioned below:-

  • It is a continuous process of dye fixation.
  • This method is the best of the three methods.
  • Dye is fixed at 1000-1800C for 2-1 minutes by radiators.
  • Higher productivity.
  • No loss of colour.
  • Dyes with medium sublimation fastness can be applied.
  • The fabric handle is very soft.

High Pressure Steaming:
The features of this method of dye fixation are mentioned below:-

  • Discontinuous process of dye fixation
  • Low productivity.
  • Dye fixation is done by high pressure steam.
  • Low production so costly process.
  • Dyes with low sublimation fastness can be applied.
  • It gives good Colour yield and bright print & smoothness.

Reduction Cleaning:
After the fabric is applied dye fixation method it is subjected to reduction cleaning process. Reduction cleaning process is carried out for obtaining deep shade (>5%-15%)

For reduction cleaning a bath is prepared containing:-

  • Caustic Soda                :           2 gm/litre
  • Hydrosulphite              :           2 gm/litre
  • Na-ionic Datergent       :           2 gm/litre
  • M : L Ratio                     :           1:5
  • Time                            :           30 Minutes

In the bath caustic soda and Hyd- rosulphite are taken for the stripping of dye and non-ionic detergents is taken for washing off. After passing the printed fabric through this bath then the fabric is washed off, by hot air & then with cold water.

Printing by White discharge style on unfixed ground:
In this method the cloth is firstly padded with a disperson of dye containing 2 gm/ litre Na- alginate to reduce the viscosity of the solution & tartaric acid to keep the pH between 5-6. The fabric is squeezed (70% pickup) dried up at 900-1000C.

Then it is printed with a paste containing:

  • Citric Acid                     :           30 Parts
  • Thio-diethylene glycol :           50 Parts
  • Water                             :           70 Parts
  • Safolin                            :           200 Parts
  • Locust Bean Gum         :           650 Parts

–––––––––––––––––––––––––––––––––––––––
……….Total                              :          1000 Parts

Here safolin is a reducing or discharging agent, and thio- dietylene glycol is used as a solvent as well as softeners and hygroscopic agents. The fixation is thermofixation process.

Color resist style of printing
At first the polyester fabric is padded in a disperson containing:-

  • Citric Acid                  :           5 Parts
  • Dispersol PC Dye       :           50 Parts
  • Water                         :           845 Parts
  • Na- Alginate              :           100 Parts
    –––––––––––––––––––––––––––––––––––
    ……………………………………1000 Parts

Here citric acid controls the pH of the liquor, Na-Alginate act as a binder and water as a solvent.

After padding the fabric is dried at 1000C & printed with the following recipe:

  • Alkali resist Disperse Dye         :           50 Parts
  • Caustic Soda/Soda Ash            :           50 Parts
  • Glycerine                                 :           100 Parts
  • Polyetylene Glycol                    :           102 Parts
  • Water                                      :           18 Parts
  •  Mey Progum                          :           600 Parts
    ––––––––––––––––––––––––––––––––––––––––––––––
    ………………………………………………..1000 Parts

After printing, the fabric is dried at 1100C and steamed for 5 minutes at 1800C with super heated steam.

Dyeing of Polyester Fabric with Carrier Method:

Standard Recipe:

  • TerasilBlue                                                     = 0.1 %
  • Terasil RedW-4BS                                          = 0.2%
  • Terasil G.Yellow-3.R                                      = 0.4%
  • Dispersing agent                                             = 1-3 g/l
  • Carrier                                                             = 2-3 g/l
  • Acetic Acid                                                     = 1-2 g/l
  • pH                                                                   = 4-6
  • Temperature                                                    = 90±5ºC
  • Time                                                                = 30-40 minutes

Procedure

  1. At first, a paste of dye and dispersing agent is prepared and then water is added to it.
  2. Dye bath is kept at 60°C temperature and all the chemicals along with the material are added to it. Then the bath is kept for 15 min without raising the temperature.
  3. PH of bath is controlled by acetic acid at 4-5.5.
  4. Now temperature of dye bath is raised to 90°C and at that temperature the bath is kept for 60 min.
  5. Then temperature is lowered to 60°C and resist and reduction cleaning is done if required. Reduction cleaning is done only to improve the wash fastness.
  6. Material is again rinsed well after reduction cleaning and then dried.

Dyeing of Polyester fabric with disperse dye in HT/HP method:

Standard Recipe:

  • TerasilBlue                                                   = 0.1 %
  • Terasil RedW-4BS                                          = 0.2%
  • Terasil G.Yellow-3.R                                      = 0.4%
  • Dispersing agent                                             = 1-3 g/l
  • Acetic Acid                                                     = 1-2 g/l
  • pH                                                                   = 4-6
  • Temperature                                                    = 1250±5ºC
  • Time                                                                = 30-40 minutes

Procedure

  1. At first a paste of dye and dispersing agent is prepared and water is added to it.
  2. pH is controlled by adding acetic acid.
  3. This condition is kept for 15 minutes at temperature 60°C.
  4. Then the dye bath temperature is raised to 130°C and this temperature is maintained for 1 hour. Within this time, dye is diffused in dye bath, adsorbed by the fibre and thus required shade is obtained.
  5. The dye bath is cooled as early as possible after dyeing at 60°C.
  6. The fabric is hot rinsed and reduction cleaning is done if required.
  7. Then the fabric is finally rinsed and dried.

Dyeing of Polyester Fabric with Disperse Dye in Pad Thermosol Method:

Standard Recipe:

  • Terasil RedW-4BS                                         = 1.5%
  • Terasil G.Yellow-3.R                                     = 0.5%
  • Dispersing agent                                            = 1-2 g/l
  • Acetic Acid                                                     = 1-2 g/l
  • pH                                                                   = 4-6
  • Temperature                                                  = 1800 – 200ºC
  • Time                                                                = 40 sec- 1 minutes
  • M:L                                                                 = 1:5

Procedure

  1. At first the fabric is padded with dye solution using above recipe in a three bowl padding mangle.
  2. Then the fabric is dried at 100°C temperature in dryer. For dyeing, infra red drying method is an ideal method by which water is evaporated from fabric in vapor form. This eliminates the migration of dye particles.
  3. Then the fabric is passed through thermosol unit where thermo fixing is done at about 205°C temp for 60-90 seconds depending on type of fibre, dye and depth of shade. In thermosol process about 75-90% dye is fixed on fabric.
  4. After thermo fixing the unfixed dyes are washed off along with thickener and other chemicals by warm water.
  5. Then soap wash or reduction cleaning is done if required. And finally the fabric is washed and dried.

Printing of Polyester Fabric with Disperse Dyes:

Standard Recipe:

  • Dyes                                                   = 2 parts
  • Thickener (Na-alginate)                    = 70 parts
  • (NH4)2SO4                                        = 0.7 parts
  • Dispersing Agent                                = 2 parts
  • NaClO3                                               = 0.2 parts
  • Water                                                  = as required

Procedure

  1. At first a thickener paste is prepared according to the recipe.
  2. Then dye and dispersing agent is mixed together.
  3. After that ammonium sulphate and sodium chlorate solution is prepared and added together.
  4. Then all the solution is added with the thickener.
  5. Thus print paste is prepared.
  6. The fabric is prepared for printing.
  7. Then the fabric is printed with block and screen method.
  8. After printing the fabric is washed well.

You may also like:

  1. Dyeing of Polyester Fabric with Disperse Dyes
  2. Printing of Polyester Fabric with Disperse Dyes
  3. Dyeing Process of Cotton Fabric with Azoic Dyes
  4. Printing of Cotton Fabric with Reactive Dyes
  5. Dyeing of Cotton Fabric with Reactive Dyes
  6. Different Types of Reactive Dyes: Properties, Structures and Factors
  7. Dyeing of Cotton Fabric with Sulphur Dyes
  8. Chrome Dyes: Features and Chemical Classification
  9. Different Types of Dyes with Chemical Structure

Share this Article!

Leave a Comment