Sulfur dyes are a kind of sulfur-containing dyes. The molecule contains sulfur bonds composed of two or more sulfur atoms. When applied, it is reduced to a leuco body, dissolved in water, and dyed fibers. The dyeing characteristics of sulfur dyes vary depending on the type of dye. Sulfur dyes have high washing fastness and strong applicability. Although rubbing fastness and vividness are not as good as reactive dyes, their color fastness and light fastness are better than reactive dyes. Sulfur dyes use less salt and consume less water when dyeing. less. Sulfur dyes are organic compounds containing nitro and amino groups, most of which are formed by reacting with sulfur and sodium sulfide at high temperatures. Many sulfur dyes do not have a certain chemical formula. The dyeing principle of sulfur dyes is similar to that of vat dyes. They form a water-soluble leuco body dyeing fiber with affinity through chemical reduction reaction, and then bind tightly to the fiber through an oxidation process.
Sulfur dyes are insoluble in water. Sodium sulfide or other reducing agents are required to reduce the dyes to soluble leucos. It has affinity for fibers and dyes the fibers, and then restores its insoluble state after oxidation and color development and is fixed on the fibers. So sulfur dyes are also a kind of vat dyes. Sulfur dyes can be used for dyeing cotton, linen, viscose and other fibers. Its manufacturing process is simple and low in cost. It can be dyed in single colors and can also be color-matched. It has good fastness to light and poor fastness to abrasion. The color spectrum lacks red and purple, and the color is dark, suitable for dyeing deep colors.