Direct dye is a dye that can directly dyes cellulose fibers in a neutral or weakly alkaline medium, usually without the use of mordants. Direct dyes are widely used in the dyeing of cotton, viscose, silk and linen, and sometimes in the dyeing of nylon and wool. In addition, it is used in large quantities for paper and leather coloring, especially on paper, about 60% of paper dyes are direct dyes.
In recent years, direct dyes have developed rapidly in China. In the development of new direct dye varieties, direct research on direct dyes, direct light fasteners, and the elimination of dye substitutes in paper dyeing. The development of new varieties of direct dyes has attracted a lot of domestic attention.