What is the difference between Sulphur Black BR and sodium sulfide?

Sulphur Black BR is also called vulcanizate or green sulfide. It is the most consumed sulfur dyes. The dye Sulphur Black BR has appearance of shinning black cristal or black power. It is not soluble in water. Soluble in sodium sulfide solution to form a dark green leuco. Soluble in hot concentrated sulphuric acid is green-blue, diluted to form black precipitation.

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Sulphur Black 1 is mainly used for dyeing cotton and hemp fibers. 2,4-dinitrophenol sodium salt was prepared by hydrolysis of 2,4-dinitrochlorobenzene, sulfurization with sodium polysulfide and air oxidation. Obviously, Sulphur Black 1 structure belongs to organic sodium sulfide salt, which is totally different from inorganic sodium sulfide. Its structure and properties are distinctly different. But one thing is related, that is, Sulphur Black can be dissolved in sodium sulfide solution and then dyed.

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Sulfur black dyes are water-insoluble dyes, so sulfur dyes themselves do not have dyeing ability for cotton. However, it has good dyeing properties for cotton when the dye is reduced to leuco in the aqueous solution of sodium sulfide (Na2S). So the dyeing of sulfur dyes should be carried out in sodium sulfide solution, and a variety of auxiliaries such as soda, sodium bicarbonate and other additives should be added.


Post time: Jun-26-2019