Sulphur dyes have been in existence for more than one hundred years. The first sulphur dyes were produced by Croissant and Bretonniere in 1873. They used materials containing organic fibers, such as wood chips, humus, bran, waste cotton, and waste Paper etc., obtained by heating alkali sulfide and polysulfide alkali. This dark-colored and foul-smelling hygroscopic dye has an unfixed composition in the alkali bath and is easily soluble in water. When cotton is dyed in an alkali bath and a sulfur bath, green dyes can be obtained. When exposed to the air or chemically oxidized with a dichromate solution for color fixation, the cotton cloth can turn brown. Because these dyes have excellent dyeing properties and low prices, they can be used in the cotton dyeing industry.
In 1893, R. Vikal melted p-aminophenol with sodium sulfide and sulfur to produce sulphur black dyes. He also discovered that eutectic of certain benzene and naphthalene derivatives with sulfur and sodium sulfide can produce a variety of sulphur black dyes. Since then, people have developed sulphur blue dyes, Sulphur red dyes and sulphur green dyes on this basis. At the same time, the preparation method and dyeing process have also been greatly improved. Water-soluble sulphur dyes, liquid sulphur dyes and environmentally friendly sulphur dyes have appeared one after another, making sulphur dyes be vigorously developed.
Sulphur dyes are one of the most widely used dyes. According to reports, the world’s output of sulphur dyes reaches hundreds of thousands of tons, and the most important variety is sulphur black. The output of sulphur black accounts for 75%-85% of the total output of sulphur dyes. Because of its simple synthesis, low cost, good fastness, and non-carcinogenicity, it is favored by various printing and dyeing manufacturers. It is widely used in the dyeing of cotton and other cellulose fibers, with black and blue series being the most widely used.