In textile processing, stripping agents are used to remove color from dyed fabric. There are generally two types of stripping.
Back Stripping: This method is used to reduce the depth of color. It involves the selective extraction of dye molecules from the textile substrate without causing significant damage to the fabric. Back stripping relies on chemicals, solvents, or detergents, often in conjunction with controlled temperature and pH conditions.
Destructive Stripping: This is a more aggressive approach used to completely remove the dye. It may involve harsh chemicals or strong acids, especially when the fabric is to be completely re-dyed. Common stripping agents include Salts of Sulfinic Acid derivatives, which are leading agents in the industry for this purpose. The choice of stripping agent depends on factors like the type of dye, fiber material, and the desired outcome of the stripping process.
Polyester, a synthetic fiber, is known for its durability, resistance to stretching and shrinking, and its ability to retain its shape. However, these same properties can make dyeing polyester a challenge. This is where auxiliaries come into play, particularly when it comes to stripping or retarding the dyeing process.
The use of auxiliaries in polyester dyeing is an intricate science that requires a deep understanding of both the materials and the chemicals involved. Stripping and retarding agents, along with other auxiliaries, ensure that the dyeing process produces the desired results with the highest quality.
The Role of Stripping Agents and Retarding Auxiliaries
Stripping agents are essential when correcting dyeing mistakes or removing color from polyester fabrics. These agents work by breaking down the dye molecules, allowing them to be washed away from the fabric. The effective class of stripping agents includes compounds with long-chain alkyl groups, such as quaternary ammonium compounds. These reduce the surface tension between the dye bath and the polyester fibers, improving the wettability of the fabric. Retarding agents slow down the rate at which dye molecules attach to the polyester fibers. This ensures a more level and even dyeing process, preventing patchiness and uneven coloration. The use of retarding agents is crucial in achieving uniform color distribution.
Nestor Industries manufactures a special auxiliary for stripping called Nestogen PLA. It is a Non-ionic levelling, stripping and synchronising agent for disperse dyes on polyester.
* Nestogen PLA is an excellent leveling agent for disperse dyeing of polyester.
* Nestogen PLA strips disperse dye from polyester and hence can be used for faulty dyeing correction.
* It can be used as reduction clearing assistant as it removes superficial dyes and improves fastness propertie
* It can be used in the application of optical brighteners.
* Nestogen PLA is non -toxic.
Type Non-ionic
Constitution Ethylene oxide condensate of Veg. oil
Appearance Lemon yellow to brown clear viscous liquid
Solubility Easily soluble in water, organic solvents, liquid fatty
acids, common vegetable oils and mineral oils.
Compatibility Compatible with weak alkalies and acids particularly
at lower temperature.
- Storage Stable under normal conditions.
Application
1. As Dye Leveling agent
Set the dyebath at 60oC with
Nestogen DAN 0.5-1.0 g/l
Nestogen PLA 0.25-0.5 g/l
Acetic acid/buffer to pH = 4.5 to 5.0
Carry out normal dyeing cycle
2. As Stripping agent for repair of faulty dyeing
For 20-30% reduction in depth
Acetic acid to pH = 4.5-5.5
For 60-70% reduction
Caustic soda to pH = 9.5-10.5
Nestogen PLA 2.0-4.0 g/l
Treat for 30 minutes at 130oC.
3. As Reduction clearing assistant
Nestogen PLA 2 g/l
In the reduction clearing bath with sodium hydrosulphite and caustic soda and treat for 30 mins at 70oC.
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