Padding Process

One Bath Pad-batch Process :

This process can be used for all Cellulisics fabric. The process consists of

Padding	Here is picked up by the fabric.
Batching	Dye is fixed.
After-treatment	To remove unfixed dyestuffs.

Preparation of Padding Liquor :

The Dye is dissolved by pouring small quantity of boiling water under stirring. This is then diluted with cold water. Urea is added 40°C.

Quantity of Urea to be added :

Strength of Dye Solution	Upto 20 gms/lit.	20 to 35 gms/lit.
Urea	100 gms/lit.	200 gms/lit.)

Required quantity of Sodium Silicate and Caustic Soda are added to the padding solution in dilute form just prior to entering the fabric. The quantity of caustic required for various grades of Sodium Silicates are tabulated below :

Sodium Silicate		Caustic Soda 32%, ml/lit.
°Be	Weight   Ratio Na2O : SiO2	Gms/lit.	Upto 25 gms/lit. Dye Solution	Above 25 gms/lit. Dye Solution
37 — 40 40 — 42 48 — 50 58 — 60	1 : 3.3 1 : 3.3 1 : 2.6 1 : 2.1	135 120 100 85	13 11 5 —	18 16 10 4

Padding :

Well prepared fabric is padded at 20-30°C. Smaller capacity through is batter as it would entail faster liquor replenishment at higher fabric speed. The liquor pickup should be 60-70% for cotton and 90-100% for viscose fabrics. Kindly note that the dye solution is not stable under alkaline condition and as such the desired alkali is to be added just prior to dyeing. Further, the speed of operation should be such that the dye liquor prepared in a lot is consumed within 20-30 minutes.

Fixation :

If fixation is done at 25-30°C, then the padded cloth roll is covered with plastic film and allowed to batch for 24 hours. No significant damage is seen upto 48 hours of batching.

Behaviour of 'VS' based Dyestuffs during one-bath Pad-batch Process using Sodium Silicate.

Solubility in presence of Alkali
'VS' based Dyestuffs	Without Urea	100 gms/l Urea	100 gms/l Urea	Stability at 30°C
	gms/l	gms/l	gms/l	in munutes
Brill. Yellow	75			30
Yellow FG	100			30
Yellow GR	100			60
Yellow RTN	100			60
Brill. Red 5B	60			120
Brill. Violet	75			60
Blue 3R	100			60
Brill. Blue R	100	150	150	60
Turq. Blue G	75	-	-	120
Brown GR	100	-	-	120
Black B	100	-	-	45

Note:
Following dyes are not suitable for this purpose due to either insufficient solubility or stability of the padding liquor.
- Golden Yellow G Brill.
- Orange 3R.

Short time Pad-batch Process :

The dyestuff solution and the Alkali solution are prepared separately and passed through metering and mixing device into the pad through. The ration of the dyes solution and Alkali mixtures is kept as 4:1, (Since majority of the dye Alkali mixing machine should be started just before beginning of the dyeing.)

Dissolving of the Dyestuffs :

The procedure for dissolution of the dyestuffs is same as given in the one-bath pad-batch process.

Padding :

Pre-scoured, cold goods are padded at the temperature between 25 to 30°C. The liquor pick-up should be 60 70% in case of cotton and 90-110% with rayon staple fiber fabrics.

Fixation :

After padding, the goods are batched. Care should be taken that selvedges are perfectly aligned on the roller. Afterwards, the roller is completely enclosed by a plastic sheet which should be tied firmly to the roller close to the selvedges. The minimum fixation time can be seen from the table given below. Even if the batching time is exceeded by few hours, except for few dyestuffs, it does not influence the final shade. If the running time in the batching operation is more than 45 minutes, it is recommended that the goods are batched for longer time than actually necessary (about 12 hours or overnight).

After-treatments :

The after-treatments is same as given in one-bath pad-batch process. Properties of 'VS' based Reactive Dyestuffs in short time Pad-batch Process using Sodium Silicate and Caustic Soda mixture.

Properties of 'VS' based Reactive Dyestuffs in short time Pad-batch
Process using Sodium Silicate and Caustic Soda mixture

Feed the dye powder steadily into the vortex created by a high-speed stirrer running in water at a temperature not higher than 50°C for ICHOFIX^® 'M" Dyes, 80°C for ICHOFIX^® 'H' & 'HE' Dyes, or

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 Discharge Printing with 'VS' based Dyes

General :

'VS' Dyes are suitable for discharge printing. Cotton fabrics discharge is better than Spun Viscose fabrics. Prior to discharge printing, the dyed fabric should be treated with Resist Salt-0 solution containing a little Lactic or Glycolic Acid. This will protect the ground shade from Alkali and reductive effect of printing paste.

Preparation of Printing Past (Typical) :

	I - gms	II - gms
Rengolite-C	20	20
Titanium Dioxide (1:1)	10	10
Leucotrope-W/Discharge Salt-W	8	-
Thickening Agent	40	50
30°Be'	Caustic20	5
Water	2	15
Total	100	100

Suitable thickening agents are Starch, British Gum, Cystal, Tragacanth as well as their mixtures.

After printing it is dried at 90°C and steamed for 5 to 10 minutes. The fabrics is then rinsed in open width soaper, first cold, then warm. Subsequently it is washed with a neutral detergent at 90°C, rinsed with cold water and dried.

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 Cold Dwell Method — Silicate Method

After printing with ICHOFIX^® "H" Brand and ICHOZOL^® Dyes by screen the printed cloth is dried. The cloth is padded with 98 parts Sodium Silicate of 102 to 104°Tw and 2 parts Caustic Soda applying 100% to 125% expression and piled in rope from in an iron drum with polythene bag inside. When the drum is full with piled cloth it is covered with a plastic sheet and allowed to remain in that position for 10 hours or say overnight. Next day this cloth is given harsh cold wash to remove silicate from the cloth. Beating is given to make sure that silicate is completely removed. This is followed by soaping at boil, washing etc. While washing silicate from printed cloth addition of small amount of polyphosphate to the hot washing bath is useful.

Key to Abbreviations :

Y	= Yellower	Str	Stronger
G	= Greener	W	Weaker
H	= Redder	L	Low
Br	= Brighter	M	Medium*
D	= Duller	H	High*
Light : 1 to 8 in increasing order
Washing & other : 1 to 5 in increasing order

* Substantivity or reactivity on unmercerised cotton