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Reactive Dyeing Process: Vinylsulphone or Vinyl Sulfones:
These reactive groups are normally transients, and are masked by water solubilizing leaving groups and their name is abbreviated to VS. The Vinyl sulfone groups are actually written as -SO2-CH=CH2,
but we cannot find this group in actual dye-bath. What we may see is: -SO2-CH2-CH2-OSO3-(H+ or Na+), depending up on the pH.
This VS group has the following disadvantages against its new counter parts such bifunctional dyes, HE dyes etc.
- Low efficiency of fixation to the fiber (40 to 50%)
- Highly colored effluent discharge
- High dosages of salt and alkali
The Dyeing Procedures:
Vinyl sulphone dyes may be applied using any one
of the following methods according to the substrate quality machinery available
and final quality requirements of the dyed material. In some cases, even a difficult
shade like purple, olives, grays and metameric browns require special process
sequences.
For any one of the application, we have to set
the dye bath with suitable auxiliary chemicals as may be required for the
purpose of maintaining the dyeing conditions throughout the length of the
process.
The following recipe suggests a sharpening dye
bath, which you may alter according to your conditions.
Dye bath Sharpening Recipe:
a. Acetic Acid 0.30 to 0.50 gram/liter
b. Sequestering Agent 0.5 to 1.00 gram/liter
c. Leveling Agent 0.5 to 0.75 gram/liter
d. De-foaming Agent * 0.1 to 0.3 gram/liter
e. Lubricating Agent 0.25 to 0.4 gram/liter
f. Mono sodium Phosphate ** 0.20 to 0.25 gram/liter
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on Reactive Dyeing:
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