What dye is used to dye cotton cloth?

Cotton cloth is dyed with vat dyes or reactive dyes.

Vat dyes are bright in color, safe in chromatography, washable and light-resistant, and are important dyes for cotton and other cellulose fibers. The vat dyes are insoluble in water, reduced to soluble leuco sodium salt in alkaline solution, adsorbed on the fabric to be dyed, and then oxidized and reduced to insoluble dyes, thus being fixed on the fabric.

Reactive dyes have the characteristics of bright color, good dyeing uniformity, simple dyeing method, high dyeing fastness, complete chromatography and low cost, and are mainly used for dyeing and printing cotton, hemp, viscose, silk, wool and other fibers and their blended fabrics.

Extended data:

After vat dyes are reduced and dissolved into colorless sodium salts by sodium hydrosulfite and caustic soda, they have a direct effect on cellulose fibers, first adsorbed on the fiber surface, and then diffused into the fiber to complete the dyeing of the fiber.

Because the dye solution contains a lot of electrolytes, it has a more direct effect on the fiber, so the dyeing speed of the fiber is faster, the dye transfer performance is poor, and it is often difficult to dye evenly. Therefore, a small amount of retarding agents can be added in the dyeing process, such as peregal 0 and Niu Pijiao.

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