DIRECT DYES Usage And Synthesis

Uses

Direct dyes are water-soluble anionic dyes, but are not classified as acid dyes because the acid groups are not the means of attachment to the fiber.

Uses

They are used for the direct dyeing of cotton and regenerated cellulose, paper, and leather. They are also used to dye union goods (mixed cotton, and wool or silk) and to a lesser extent nylon fiber. Most of the dyes in this class are polyazo compounds, along with some stilbenes, phthalocyanines, and oxazines. The solubility of the dye in the dye bath is often reduced by adding common salt or Glauber's salt. The presence of excess sodium ions favors establishment of equilibrium with a minimum of dye remaining in the dye bath.

Definition

A group of dyes that are mostly azo-compounds derived from benzidene or benzidene derivatives. They are used to dye cotton, viscose rayon, and other cellulose fibers directly, using a neutral bath containing sodium chloride or sodium sulfate as a mordant.