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Dyeing and Finishing-1
Dyeing and Finishing-2
Industry Information New Additions
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Reactive Dyes on CelluloseVinylsulphone 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.
The Dyeing Procedures: The application part of Vinyl-Sulphone, is purely dependent on the construction of fabric, the type of machinery available and the difficultly of the shade to obtain. All these things are to be taken care of by a qualified Dyeing Master. We can see the various types of procedures in the application. 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 COLD PROCESS – SALT SODA REQUIREMENTS: The above recommendations are for un-mercerized cotton in the Material Liquor Ratio (MLR) 1:7 to 1:15.
PRECONDITIONING METHOD:
A – Add ½ the qty of Salt + ½ the qty of Soda + ¼ qty of Caustic Run 10 minutes B-- Add ½ the qty of Salt + ½ the qty of Soda + ¼ qty of Caustic Run 10 minutes C-- Add ½ the qty of pre-dissolved and filtered dye Run 10 minutes D-- Add ½ the qty of pre-dissolved and filtered dye Raise the temperature to 40 to 45°C on the fabric Run 30 minutes – Check the shade and tone it if necessary. E--Add ¼ the qty of Caustic Soda Run 10 minutes F--Add ¼ the qty of Caustic Soda G--Run at 45°C for 90 minutes. Drain --- Cold Running Wash – Neutralize – Hot wash – Hot Wash -Cold Wash – Soap at Boil – Fix and do softening as required. (All hot washes should be done at min 60°C with good quality water). This method is suitable for light to medium density fabrics and for medium to heavy depth of shades. This method not only yields uniform shade but also gives around 20 to 30% more color yield, higher rubbing and wash fastness results, which are mainly due to the full exhaustion and fixation of the dye. The above method has been followed continuously in reputed dye houses in South India, for jigger and winch dyeing. HOT PROCESS – CHEMICAL REQUIREMENTS:
ALL IN ONE METHOD :
This is a general method suitable for light to dark shades up to medium density fabrics. ISO THERMAL METHOD:
This is a versatile method suitable for all kinds of well absorbent fabrics. TEMPERATURE INCREASING METHOD:
This method gives better levelness in very difficult shades as well. COOLING METHOD :
This method is effective for retarding initial dye adsorption, improving dye migration and also for swelling the fiber, to improve dye penetration. This method is therefore suitable for dyeing densely loaded materials, high GSM fabrics and mercerized cotton/viscose materials. A special note on Soft-Flow Dyeing : For soft-flow type of machines, under controlled conditions of water quality and pH maintenance, amore precise Chemical table as given below will be of much use.
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