4.6.1. Cellulose dyeing. Batch methods of dyeing

Batch methods are used for fiber, yarn, fabric and knitwear dyeing with any type of dyeing equipment. It is recommended to carry out the dyeing process on low bath modulus equipment in the presence of electrolyte and alkaline agent, the amount of which depends on color intensity and bath modulus.

Table 4.1. Dyes Bath Composition and Dyeing Conditions

Solution components	Reactive dyes
	with ,,Kh" index	without any index
Dye, % based on material to be dyed	up to 5	up to 5
Common Sail, g/ 1	50	40—80
Soda Ash, g/1	5—0	12 — 25
or Caustic Soda (32,5%), g/1	-	3—5,5
Temperature, ^oС	25—40	70—80
Bath Modulus	1:5—1:20	1:5—1:20
Time, min.	40—60	60

Common salt and alkaline agent are added into the dyeing bath twice with a ten minutes interval. When using non-indexed dyes the dyeing process begins at 40 °C. After half of the necessary amount of the common salt is added the dye bath is heated up to 70—80 °C for 10 minutes and the rest of common salt is added and then the alkaline agent is added twice with a 10 minutes interval.

4.6.2. Continuous dyeing

Continuous dyeings may follow different technologies depending on equipment available and the properties of the dyes used. The commonest method allowing the usage of all the reactive dyes and yielding any color intensity is the padding and steaming method with intervening drying.

Table 4.2. Padding Solutions Composition and Fixation Conditions

Solution Components, g/1 and Dyeing Conditions	Reactive Dyes
	with „Kh” index	non-indexed
Dye	x	x
Wetting Agent	1—2	1—2
Urea	100—150	50—100
Ludigol	10—15	5—10
Sodium Bicarbonate	5—10	-
Soda Ash	-	10—20
Padding Solution Temperature, °C	20—25	20—25
Fixation Conditions Steaming Temperature, °C	102—105	102—105
Steaming Time	20 sec.	3—10 min.

Dyeing of wool by reactive dyes

Composition of dyeing bath, %:

Dye . . . . . . . . . . . . . . . . . . . . . . .X

Syntegal V-7 or Albegal D . . . .0,75-1,0

Ammonium Sulphate . . . . . . . .2,0

Sodium sulphate . . . . . . . . . . . 5-10

Acetic acid (30%) . . . . . . . . . . . 3-5

Ammonia (25%) . . . . . . till рН=8,0-8,5

Water. . . . . . . . . . . . . . . . . . . . . .Y

Procedure of dyeing

Dyeing bath with all auxiliary substances and dyes should be heated for 60 min. up to boiling and dye under boiling for 45-60 min. At the end of dyeing the above bath cool down till 80°C, solution of ammonia is added till pH=8,0-8,5 and treat at this temperature for 15 min. Then washing out is followed in warm and cold running water.