The principle of color extraction agent

Color pulling, also known as color stripping, generally uses chemical reactions to destroy the combination of dyes on fibers and fibers, destroy the structure of dyes on fibers, and make dyes peel off fibers and cannot develop color.

There are two main types of commonly used color removal agents: reducing color removal agents and oxidative color removal agents.

1. Restore color stripping agent

Commonly used are hydrosulfite and carving white powder. They achieve the purpose of fading and decolorizing by destroying the chromogenic system in the molecular structure of the dye. For dyes with an azo structure, the azo group can be reduced to an amino group without color development. However, the damage of the reducing agent to the color-forming system of some structural dyes is reversible, such as the color-forming system of anthraquinone structure, so its fading is recoverable.

2. Oxidation color stripping agent

Commonly used are hydrogen peroxide and sodium hypochlorite. Under certain conditions, the oxidizing agent can destroy some groups that make up the chromogenic system of dye molecules, such as decomposing azo groups, ammoxidation, hydroxymethylation, and detachment of complexed metal ions. These irreversible structural changes can lead to fading and decolorization of dyes. Therefore, in theory, oxidative color extraction agents can achieve complete color extraction, and the use of such color extraction agents for dyes with anthraquinone structure has a particularly good effect.

3. Exhaustion rate

E represents the exhaustion rate of dyeing, which is characterized by the final color depth and dosage ratio.