Nowadays, sulfur powder is a powdery substance made from sulfur. So what are the methods used to produce sulfur dyes?
The baking method of sulfur powder involves baking amines, phenols or nitro compounds of aromatic hydrocarbons with sulfur or sodium polysulfide at high temperatures to produce yellow, orange and brown sulfur dyes. In the boiling method, amines, phenols or nitro compounds of aromatic hydrocarbons and sodium polysulfide are heated and boiled in water or organic solvents to prepare black, blue and green sulfur dyes. Similar to direct dyes, salt can be used to promote dyeing. Cationic color-fixing agents and metal salt color-fixing agents are used to improve fastness.
Sulfur powder is similar to vat dyes. The dye needs to be restored to leuco body with a reducing agent before it can be dyed on the fiber and oxidized on the fiber. It’s just that the strong reducing agent insurance powder is not used, but the weak reducing agent sodium sulfide is used. However, the directness of the reduced leucobody to the fiber is lower than that of the vat dye, and the dye has a greater tendency to aggregate. When reacting with acid, sulfur powder can generate hydrogen sulfide gas, and when reacting with aluminum acetate, it can produce black aluminum sulfide accumulation. Sulfur tablets can use higher temperatures to increase the diffusion rate of the dye and improve the degree of dyeing.