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DYEING
PROCEDURE
DYEING
METHOD WITH BI-FUNCTIONAL DYES
Bi-functional dyes are applicable by both exhaust dyeing method
as well as pad-dyeing method.
i) Exhaust dyeing methods
Bi-functional dyes
are applicable by exhaust dyeing methods in following different
ways.
(a) Increase temperature method
Procedure:
Set the
dye-bath 25 deg c with dye solution and carry out dyeing for 10
minutes. Then add half amount of salt and continue dyeing by
raising temperature to 45 deg c in 10 minutes. Add remaining
half the amount of salt at 45 deg c and raise the temperature to
60 deg. C in 10 minutes with continued dyeing. Continue dyeing
60 deg. C for further 5 minutes and then add half amount of soda
ash and dyeing is continued for further 50 minutes at 60 deg. C.
The goods are then washed off.
Salt & Alkali Requirements:
|
% Shade * |
Glaubers Salt gms/l |
Soda Ash gms/l |
1.0 to 2.0
2.0 to above |
35 to 50
50 |
15
15-20 |
* For light shades of less than 1%, quantity
of Glauber's salt and soda ash to be reduced appropriately.
Temperature increasing method.
This method
gives better levelness when it is difficult to obtain level
dyeing.
(b) Constant temperature method.
Procedure
Set the dye-bath at 60 deg. C with the dye
solution. Carry out dyeing at 60 deg. C for 10 minutes. Then add
salt at 60 deg. C and continue dyeing for 25 minutes. Add half
the amount of soda ash and continue dyeing for 10 minutes. Then
add remaining half amount of soda ash and continue dyeing for
further 50 minutes at 60 deg.
C. the goods are then washed off.
Salt & Alkali requirements: same as (8)
(c) All-in Method
This method is particularly suitable for
unmercerised cotton produce deep shades. Moreover this method is
applicable to vinylsulfone dyes and hence combination of
vinylsulfone dyes is possible.
Process
Set the dye-bath at 20-30 deg. C. Add salt
and continue dyeing for 5 to 10 minutes. Then dye solution and
continue for 15-20 minutes. Now add half amount of alkali and
dye for 5-10 minutes. Add remaining 1/2 amount of alkali and
continue for further 5 to 10 minutes. Then raise temperature to
50 - 60 deg. C in 20 minutes.(1.5 deg. C rise/minute) and
continue dyeing at 50 - 60 deg. C for 45 - 60 minutes.
"New all-in" Method
The "new all-in" method with Bi-functional
dyes gives an ideal rate of dyeing in terms of levelness and
reproducibility even after the addition of alkali, but it is
necessary to take into account the type of dyeing machines and
the form of materials to be dyed.
Suitability for cheese dyeing
The suitability
for cheese dyeing was measured as follows:
|
Dyeing depth
Glauber's salt anhydrous
Soda ash
Goods : Liquor ratio
Temperature and time
|
: 3.0% o.w.f.
: 50 g/l
: 20 g/l
: 1:20
: 60oC, 60 minutes
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ii) Pad dyeing method
(a) Pad batch method
|
Padding liquor |
Dyestuff |
x parts |
|
|
Urea |
50 parts |
|
|
Water
Sodium Silicate
(134-142oTw
Na2O : SiO2 1:2.1 |
remaining
85 parts |
|
|
Caustic Soda 33% |
4 parts |
|
|
Total |
1000 parts |
Procedure
The goods are padded in the
above padding liquor and batched on a plastic sheet and kept for
about 20 hours and then washed. However, all dyes are not
suitable by this method. Hence proper selection is to be carried
out.
It is also applicable by using Caustic Soda plus Glauber's salt
in place of Sodium Silicate + caustic soda as alkali agent in
above padding liquor. This is particularly important when dyeing
thick fabric such as corduroy because removal of silicate is
very difficult.
Caustic Soda (40oBe)
+
Glauber's Salt |
- 12 cc/litre
- 30 gms/litre |
Alkali Agent
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(b) Printing Methods
Bi-functional dyes are
applicable by various printing methods on cellulosic material
with the following advantages:
-
Suitable for various
method of printing with a high fixation degree.
-
Print paste containing
alkali has superior storage stability.
-
A smaller amount of
alkali is sufficient for dye fixation.
(a) Print - Dry - Steam - Wash - Dry (Bi-functional
dye + alkali).
|
Printing recipe |
Dyestuff |
20
parts |
| Urea |
50
parts |
Water
|
300
parts |
| Sodium
Alginate Paste |
400
parts |
| Soda
Ash |
10
parts |
| Resist
Salt |
10
parts |
Water
|
remaining |
| Total |
1000
parts |
Procedure
The goods are
printed with above print paste and dried.
The dried goods are then steamed for 7 to 10 minutes at 100 -
103 deg. C in saturated steam and washed.
(b) Print - Dry - Pad - Batch - Wash
(Bi-functional dye without alkali (Sodium Silicate)
The goods are printed with paste containing no alkali and dried.
The dried goods are then padded in a sodium silicate solution
covered with a plastic sheet and kept for 20 to 24 hours and
washed.
Washing off:
To obtain
optimum fastness properties a thorough and complete wash off
should be given to printed goods. The goods are first washed
thoroughly in cold water and then in hot water. Then boil it for
about 5 minutes to anionic detergent 1-2 parts/liter. Finally
rinse in cold water and dry. Wherever necessary a treatment with
dye-fixing agent may be given with 2-5 parts/liter of final wash
liquor.
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