Cotton is bleached using the oxidizing power of hydrogen peroxide to remove the primary contaminants such as pigment originally contained in the fiber, decompose and decolorize, and obtain the required whiteness.
At that time, the stabilizer for hydrogen peroxide bleaching is used to prevent uneven bleaching, to reduce fiber embrittlement, and to effectively use hydrogen peroxide for bleaching.
As stabilizers for hydrogen peroxide bleaching, there are types such as silicates, polycarboxylic acids, aminocarboxylic acids, optimal chemicals are selected in consideration of required whiteness, processing conditions, cost, etc.
(1) Without bleaching stabilizer
(2) With bleaching stabilizer
The decomposition of hydrogen peroxide is said to have the following two.
1. H2O2 → H+ + HOO-
2. 2H2O2 → 2H2O + O2
The combination of alkali is essential to promote decomposition.
It is the decomposition reaction of 1 that works effectively for bleaching, and the presence of metals such as iron and copper or their ions accelerates the decomposition reaction of 2.
The decomposition reaction of 2 causes oxidative degradation of cotton, which leads to strength reduction and pinholes.
Stabilizer for hydrogen peroxide bleaching achieves uniform bleaching by suppressing rapid decomposition of hydrogen peroxide.
It prevents degradation of strength and pinholes by suppressing decomposition of 2, and plays an important role to obtain high quality bleached products.