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Vinylsulphone dyestuffs may be applied on cellulose with
different dyeing procedures. One such process is the ambient temperature (room
temperature) method of dyeing.
In this method there are advantages and disadvantages.
- Slow and safe dyeing
- No fuel cost
- Good repeatability of shade
- Tightly woven or fine quality of yarn may not get uniform
impregnation and hence there may be some shade variation within the batch.
- Shades with Turquoise Blues in ambient temperature
produce poor exhaustion and fastness properties.
- Difficult shades and big batch dyeing are not
possible.
Method of dyeing:
- Make ready the dye bath with sharpening chemicals and auxiliaries.
- Add the dyestuff in to the bath slowly over a period of
time ( may 20 minutes).
- After addition of dyestuff, add the required amount of
salt in two portions or slowly ( 20 minutes).
- The add Soda ash to the dye bath in 2 portions or over a
period of 20 minutes.
- Continue dyeing for 40 minutes.
- Take sample. If the shade is slightly lighter (10% ~15%),
add the dissolved caustic soda in two portions.
- Continue dyeing for 30 minutes, drain the bath, two hot
washes followed by neutralization, soaping and cationic fixing/softening
treatments.
- On the other hand, if the shade or tone is very much
difference from the standard and you want to make more than 10% dyestuff,
you can make addition of pre-dissolved and filtered dyestuff in to the dye
bath in many portions or 20 minutes. Continue step 7.
Salt and Soda requirement:
| Depth of Shade (%) |
Salt gms/liter |
Soda ash gms/liter |
Solid caustic gms/liter |
| up to 1 |
50 |
5.0 |
0.75 |
| 1 ~ 2 |
50 |
5.0 |
1.50 |
| 2 ~ 3 |
70 |
7.5 |
2.00 |
| 3 ~ 4 |
80 |
10.0 |
3.00 |
| 4 ~ 5 |
80 |
10.0 |
3.50 |
| 8% |
80 |
10.0 |
4.00 |
The above recipes
would work from liquor ratio 1:4 to 1:12 very well. For very high liquor ratio
machines the caustic soda amount may be reduced by 20 to 30% from the above
values.
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