1. Exhaustion of the reactive dye from an aqueous bath containing common salt or Glauber’s salt normally used in neutral condition.
2. Addition of alkali to promote to further reactive dye uptake and chemical reaction of absorbed reactive dye with the fibers.
3. Dyed material with reactive dye is then rinsed and soaped to remove electrolyte, alkali and unfixed reactive dyes.
This is the first dyeing phase, that takes place in the same way as cellulose fibre dyeing with non reactive soluble dyes; in this phase the reactive dye does not decompose, but only diffuses towards the interior of the fibre, where it is absorbed by the cellulosic chains by secondary type forces.
The following dyeing parameters influence the absorption:
(b) Liquor ratio of reactive dye bath
(c) Electrolyte concentration in side the dye bath
(d) PH of the liquor
(e) Temperature of the reactive dye bath
(f) Type of the fiber to be dyed with reactive dye
(g) Reactive Dyeing time
(h) Alkali concentration in the liquor
Dyeing method for Reactive dyes:
2.Semi continuous method of reactive dyeing
a) Pad jig reactive dye method
b) Pad batch reactive dye method
3.Continuoues method of reactive dyeing
a) Pad steam reactive dye method
b) Pad thermofixation reactive dye method
Reactive Dyeing Process of Pad steam method:
This method is suitable for all types of reactive dyes. Recipe is given below:
Shade
|
Dyestuff g/l
|
Migration inhibitor
|
Soda ash g/l
|
Salt g/l
|
Urea g/l
|
Light
|
0-10
|
Small quantity of Na-alginate
|
5
|
40-60
|
150
|
Medium
|
10-20
|
Same
|
5-10
|
60-80
|
150
|
Heavy
|
>20
|
Same
|
10-20
|
80
|
150
|
Reactive Dyeing Process of pad steam method:
In pad steam method of reactive dyeing in the 1st bowl padding is done with reactive dye solution and urea at a temp of 60-800C. Here urea helps to dissolve the reactive dye completely in water and also to penetrate the reactive dye within the fiber. In some industries Na-alginate is used which act as a migration inhibitor may be add in the 1st bowl and other industries used Na-alginate in a separate bath just after padding with reactive dyes and urea. After padding with reactive dyes, urea and migration inhibitor, the fabric is then added with soda ash and salt at 600C which is known as chemical padding. Then the fabric is passed through the steam chamber at a temp of 100-1020C where it takes 30-60 sec for fixing the reactive dye with the fabric. Then the fabric is subsequently rinsed, soaped at boil and finally washed and dried to complete the dying operation.
Recipe:
Dye – 2% on the weight of material
Soda ash – 1% on the weight of material
Salt – 8% on the weight of material
Urea – 15% on the weight of material
Na-alginate – Little amount
In this method reactive dyestuff, alkali(soda ash), salt, urea and Na-alginate are mixed in the dyebath. The fabric is padded in the padding bath at room temperature. Then the padded fabric is dried in the drying unit. After drying the fabric is treated for 5 minutes at 1600C in a heating chamber for thermofixation. After thermofixation the fabric is rinsed, soaped and rinsed. This method is suitable for moderate reactivity dye.
Semi continuous method of reactive Dyeing:
Pad batch reactive dyeing method:
Recipe:
Dye – 3% on the weight of material
Soda ash – 15 g/l
Salt - 60 g/l
Urea – 150 g/l
Na-alginate – Little amount
Process of reactive dyeing:
Pad-Jig method of reactive dyeing:
Process of dyeing:
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Wish you good luck......................................................