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What Is Direct Dyes
Sep 18, 2018

Direct dyes are dyes that can be heated and boiled in neutral and weak bond media without the aid of mordants. Direct dyes are formed by the combination of direct dyes and cotton fibers with hydrogen bonding van der Waals forces. Mainly used in fiber, silk, cotton spinning, leather and other industries, and also in the paper and other industries. The direct dye can be classified into azo, stilbene or the like according to its structure. According to their application, there are mainly common direct dyes, direct fast dyes and direct azo dyes.

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The direct dye has a molecular structure in which a water-soluble group such as a sulfonic acid group (-SO3H) or a carboxyl group (-COOH) is linearly arranged. The aromatic ring structure is in the same plane,

Therefore, the direct dye has a large affinity for the cellulose fiber, and is directly dyed in a neutral medium, and the dye can be dyed by dissolving the dye in dry water.

The dye is adsorbed to the surface by the fiber in the solution and then continuously diffuses into the amorphous region of the fiber to form a combination of hydrogen bonding and van der Waals force with the fiber macromolecule.

Its derived dyes are direct fast dyes and direct copper salt dyes.