Dyeing on Polyester fabric with Disperse dyes

Introduction:

Dyes are coloured, 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. 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:

• Disperse dyes are nonionic dyes. So they are free from ionizing group.
• They are ready made dyes and are insoluble in water or have very low water solubility.
• They are organic colouring substances which are suitable for dyeing hydrophobic fibres.
• Disperse dyes are used for dyeing man made cellulose ester and synthetic fibres specially acetate and polyester fibres and sometimes nylon and acrylic fibres.
• Carrier or dispersing agents are required for dyeing with disperse dyes.
• Disperse dyes have fair to good light fastness with rating about 4-5.

Classification of Disperse Dyes:

According to Chemical Structure:

1. Nitro Dyes
2. Amino Ketone dyes
3. Anthraquinonoid dyes
4. Mono azo dyes
5. Di- azo dyes

Application Methods of Disperse Dyes:

1. Method N: Normal dyeing method. Dyeing temperature is 80-100°C.
2. Normal NC method: Method of dyeing at normal temperature with carriers. Dyeing temperature 80-100°C.
3. Method HT: High temperature dyeing method. Dyeing temperature 105-140°C.
4. Method T: Thermasol dyeing method. Dyeing temperature 180-220°C, continuous method of dyeing.
5. Pad roll method: Semi continuous dyeing method.
6. Pad steam method: Continuous dyeing method.

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.

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 Waal's 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

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. If it is kept for more time, then dye sublimation and loss of fabric strength may occur.

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 usedAt this pH dye exhaustion is satisfactory. During colour development, correct pH should be maintained otherwise fastness will be inferior and colour will be unstable.

CARRIER DYEING METHOD:

PROCEDURE:

• At first, a paste of dye and dispersing agent is prepared and then water is added to it.
• 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.
• pH of bath is controlled by acetic acid at 4-5.5.
• Now temperature of dye bath is raised to 90°C and at that temperature the bath is kept for 60 min.
• 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.
• Material is again rinsed well after reduction cleaning and then dried.

HIGH TEMPERATURE DYEING METHOD:

PROCEDURE:

• At first a paste of dye and dispersing agent is prepared and water is added to it.
• PH is controlled by adding acetic acid.
• This condition is kept for 15 minutes at temperature 60°C.
• 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.
• The dye bath is cooled as early as possible after dyeing at 60°C.
• The fabric is hot rinsed and reduction cleaning is done if required.
• Then the fabric is finally rinsed and dried.
Dyeing Curve

THERMASOL DYEING METHOD:

Dyeing of Polyester Fabric in Thermasol Dyeing Method

Thermasol 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:

Procedure:

• At first the fabric is padded with dye solution using above recipe in a three bowl padding mangle.
• 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.
• 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.
• After thermo fixing the unfixed dyes are washed off along with thickener and other chemicals by warm water.
• Then soap wash or reduction cleaning is done if required. And finally the fabric is washed and dryed.

Conclusion :

By this experiment we have acquired so much knowledge about disperse dye.we have known too much end uses of disperse dye.

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Textile Manufacturing Proces/Process Flow Chart of Textile Manufacturing

                           Textile Manufacturing Process

               Process Flow Chart of Textile Manufacturing

                                                 Spinning
                                                        ↓
                                                   Weaving
                                                        ↓
                                    Dyeing +Printing+ Finishing
                                                        ↓
                                     Garments Manufacturing
 

                                       Flow Chart of Spinning

                                                 Blowroom
                                                        ↓
                                                   Carding
                                                        ↓
                                                  Drawing
                                                        ↓
                                                  Combing
                                                        ↓
                                                  Drawing
                                                        ↓
                                     Roving Manufacturing
                                                        ↓
                                             Ring Spinning 

                                     Flow Chart of Weaving

                                  Yarn from spinning section
                                                       ↓
                                     Doubling and Twisting
                                                       ↓
                                                 Winding
                                                       ↓
                                                 Creeling
                                                       ↓
                                                Warping
                                                       ↓
                                                  Sizing
                                                       ↓
                                 Winding on weavers beam
                                                       ↓
                                                Weaving

                                      Flow Chart of Dyeing

                                     Inspection of grey cloth
                                                      ↓
                                               Stitching
                                                      ↓
                                              Cropping
                                                      ↓
                                               Brushing
                                                      ↓
                                               Singeing
                                                      ↓
                                               Desizing
                                                      ↓
                                               Scouring
                                                      ↓
                                               Bleaching
                                                      ↓
                                                 Souring
                                                      ↓
                                                Washing
                                                      ↓
                                                 Drying
                                                      ↓
                                             Mercerizing
                                                      ↓
                                                 Dyeing
                                                      ↓
                                           Aftertreatment
                                                      ↓
                                                Finishing
                                                      ↓
                                                Inspection
                                                      ↓
                                                 Packing
                                                      ↓
                                                 Baling

                                

                                                             Flow Chart of Printing

       

 Inspection of grey cloth
↓
Stitching
↓
Cropping
↓
Brushing
↓
Singeing
↓
Desizing
↓
Scouring
↓
Bleaching
↓
Souring
↓
Washing
↓
Drying
↓
Mercerizing
↓
Printing 
↓
Aftertreatment
↓
Finishing
↓
Inspection
↓
Packing
↓
Baling

Flow Chart of  Garment Manufacturing

Design / Sketch

↓

Pattern Design

↓

Sample Making

↓

Production Patter

↓
Grading

↓
Marker Making

↓

Spreading

↓

Cutting

↓

Sorting/Bundling

↓

Sewing/Assembling

↓

Inspection

↓

Pressing/ Finishing

↓

Final Inspection

                                                                                ↓

                                                                         Packing

                                                                                ↓

                                                                          Dispatch

          

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Textile fibre

Fibers used for production of yarn and fabric are called textile fibers. A unit of matter, either natural or manufactured, that forms the basic element of fabrics and other textile structures. A fiber is characterized by having a length at least 100 times its diameter or width. The term refers to units that can be spun into a yarn or made into a fabric by various methods including weaving, knitting, braiding, felting, and twisting.

Textile fiber characteristics

There are many fibers looks like textile fiber but all fiber are not textile fibers. Textile fiber must have some essential characteristics e.g.
a. Minimum length to insert twist e.g. a length of at least 5 millimeters.
b. Strength
c. Fineness
d. Pliability or Flexibility
e. Cohesiveness
f. Rigidity or stiffness
g. Elongation & Elasticity
h. Moisture Absorbency etc.

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definition of fabric

Fabric Manufacturing

Textile fabrics can be produced directly from webs of fibres by bonding, fusing or interlocking to make non-woven fabrics and felts, but their physical properties tend to restrict their potential end-usage. The mechanical manipulation of yarn into fabric is the most versatile method of manufacturing textile fabrics for a wide range of end-uses.

principal Methods of fabric manufacturing

There are three principal methods of mechanically manipulating yarn into textile fabrics:

1. interweaving
2. intertwining
3. interlooping

1.Interweaving

Interweaving or weaving is the intersection of two sets of straight threads, warp and weft, which cross and interweave at right angles to each other.Weaving is by far the oldest and most common method of producing continuous lengths of straight-edged fabric.

2.Intertwining and twisting

Intertwining and twisting includes a number of techniques, such as braiding and knotting, where threads are caused to intertwine with each other at right angles or some other angle. These techniques tend to produce special constructions whose uses are limited to very specific purposes.

3.Interlooping

Interlooping consists of forming yarn(s) into loops, each of which is typically only released after a succeeding loop has been formed and intermeshed with it so that a secure ground loop structure is achieved.The loops are also held together by the yarn passing from one to the next. Knitting is the most common method of interlooping and is second only to weaving as a method of manufacturing textile products.

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Dyeing of cotton fabric with reactive dyes

Introduction:

A dye, which is capable of reacting chemically with a substrate to form a covalent dye substrate linkage, is known as reactive dye.
Here the dye contains a reactive group and this reactive group makes covalent bond with the fibre polymer and act as an integral part of fibre. This covalent bond is formed between the dye molecules and the terminal –OH (hydroxyl) group of cellulosic fibres on between the dye molecules and the terminal –NH2 (amino) group of polyamide or wool fibres.

History:

Reactive dyes first appeared commercially in 1956, after their invention in1954 by Rattee & Stepheness at the Imperial chemical Industry (ICI). Dyestuffs Divion site in Bleckley, Manchetor. UK.

Usages:

By reactive dyes the following fibres can be dyed successfully:

1. Cotton, rayon, flax and other cellulosic fibres.
2. Polyamide and wool fibres.
3. Silk and acetate fibres.

Trade names:

Some trade names of this dye are mentioned:

Trade name	Manufacturer	Country
Procion	I.C.I	U.K
Cibacron	Ciba	Switzerland
Remazol	Hoechst	Germany
Levafix	Bayer	Germany
Reactone	Geigy	Switzerland
Primazin	BASF	Germany
Drimarine	Sandoz	Switzerland

Properties of reactive dye:

1. Reactive dyes are cationic dyes, which are used for dyeing cellulose, protein and polyamide fibres.
2. Reactive dyes are found in power, liquid and print paste form.
3. During dyeing the reactive group of this dye forms covalent bond with fibre polymer and becomes an integral parts of the fibre.
4. Reactive dyes are soluble in water.
5. They have very good light fastness with rating about 6. The dyes have very stable electron arrangement and can protect the degrading effect of ultra-violet ray.
6. Textile materials dyed with reactive dyes have very good wash fastness with rating Reactive dye gives brighter shades and has moderate rubbing fastness.
7. Dyeing method of reactive dyes is easy. It requires less time and low temperature for dyeing.
8. Reactive dyes are comparatively cheap.
9. Reactive dyes have good perspiration fastness with rating 4-5.
10. Reactive dyes have good perspiration fastness.

General structure of reactive dyes:

The general structure of reactive dye is: D-B-G-X.

Here,
D= dye part or chromogen (color producing part)
Dyes may be direct, acid, disperse, premetallised dye etc.
B = bridging part.
Bridging part may be –NH- group or –NR- group.
G = reactive group bearing part.
X= reactive group.

Classification of reactive dyes:

Reactive dyes may be classified in various ways as below:

1. On the basis of reactive group:
1. Halogen (commonly chlorine) derivatives of nitrogen containing heterocycle, like 3 types-
• Triazine group
• Pyridimine group
• Quinoxaline dyes
Example:
Triazine derivatives: procion, cibacron.
Pyridimine derivatives: reactone
Quinoxaline derivatives: levafix.

2. Activated vinyl compound:
• Vinyl sulphone
• Vinyl acrylamide
• Vinyl sulphonamide.
Example:
Vinyl sulphone: remazol
Vinyl acrylamide: primazine
Vinyl sulphonamide: levafix.


2. On the basis of reactivity:
1. Lower reactive dye:
Medium reactive dye: here pH is maintained 11-12 by using Na2CO3 in dye bath.

2. Higher reactive dye: here pH is maintained 10-11 by using NaHCO3 in dye bath.
3. On the basis of dyeing temperature:
1. Cold brand:
These types of dyes contain reactive group of high reactivity. So dyeing can be done in lower temperature i.e. 320-600C.
For example: PROCION M, LIVAFIX E.
2. Medium brand:
This type of dyes contains reactive groups of moderate reactivity. So dyeing is done in higher temperature than that of cold brand dyes i.e. in between 600-710C temperatures.
For example, Remazol, Livafix are medium brand dyes.

3. Hot brand:
This type of dye contains reactive groups of least reactivity. So high temperature is required for dyeing i.e. 720-930 C temperature is required for dyeing. For example PRICION H, CIBACRON are hot brand dyes.


Dyeing mechanism of reactive dye:

The dyeing mechanism of material with reactive dye takes place in 3 stages:-

1. 1. Exhaustion of dye in presence of electrolyte or dye absorption.
2. 2. Fixation under the influence of alkali.
3. 3. wash-off the unfixed dye from material surface.

Now they are mentioned below:

1. Dye absorption:
When fibre is immersed in dye liquor, an electrolyte is added to assist the exhaustion of dye. Here NaCl is used as the electrolyte. This electrolyte neutralize absorption. So when the textile material is introduces to dye liquor the dye is exhausted on to the fibre.
2. Fixation:
Fixation of dye means the reaction of reactive group of dye with terminal –OH or-NH2 group of fibre and thus forming strong covalent bond with the fibre and thus forming strong covalent bond with the fibre. This is an important phase, which is controlled by maintaining proper pH by adding alkali. The alkali used for this create proper pH in dye bath and do as the dye-fixing agent. The reaction takes place in this stage is shown below: -
3. Wash-off:
As the dyeing is completed, a good wash must be applied to the material to remove extra and unfixed dyes from material surface. This is necessary for level dyeing and good wash-fastness. It is done by a series of hot wash, cold wash and soap solution wash.


Application method:

These are 3 application procedures available:

1. Discontinuous method-
• Conventional method
• Exhaust or constant temperature method
• High temperature method
• Hot critical method.
2. Cotinuous method-
• Pad-steam method
• Pad dry method
• Pad thermofix method
3. Semi continuous method-
• Pad roll method
• Pad jig method
• Pad batch method.

Stripping of reactive dye:

The reactive dye cannot be satisfactory stripped from fibre due to covalent bond between dye molecule and fibre. Stripping becomes necessary when uneven dyeing occurs.
Partial stripping:
Partial stripping is obtained by treating the dyed fabric with dilute acetic acid or formic acid. Here temperature is raised to 70-100°C and treatment is continued until shade is product of hydrolysis. The amount of acid used is as below:
Glacial acetic acid : 5-10 parts
With water :1000 parts
Or
Formic acid :2.5 to 10 parts
With water :1000 parts
Temperature : 70 - 100°C
Time : until desired shade is obtained.



Different methods of reactive dye application:

1. Pad-batch method.
Pad batch processes are of two types-

1. Pad (alkali)-batch (cold) process.
2. Pad (alkali)-batch (warm or hot) process.
2. Pad dry method
3. Pad steam method.

Conclusion:

By this experiment we came to know the reactive dyes are of the least reactivity because they take more temperature and more time for dyeing.

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