Sulfur Black

Sulfur Black (C.I. Sulfur Black 1, CAS No. 1326-82-5) is a sulfur-containing macromolecular dye, appearing as black scaly solid or powder. Its chemical structure contains unstable disulfide bonds and polysulfide bonds, which are prone to oxidation to generate sulfuric acid, causing fiber embrittlement. Anti-embritlement treatment is necessary after dyeing.

Core Properties

- Physical and Chemical Properties: Insoluble in water and ethanol, soluble in sodium sulfide solution to show dark green. Its melting point is about 114.8℃, density is 1.68g/cm³. It presents yellowish olive color in alkaline sodium hydrosulfite solution, and can restore the original color after oxidation, while it fades completely in sodium hypochlorite solution.

- Anti-embritlement Feature: Traditional sulfur black is easy to oxidize due to sulfur bonds, so anti-embritlement treatment with urea, sodium carbonate, etc. is required. Anti-embritlement sulfur black adds formaldehyde and chloroacetic acid during production, which can stabilize the sulfur atom structure and avoid fiber embrittlement.

Application Fields

It is mainly used for dyeing cotton, linen, viscose fiber and viscose/cotton blended fabrics, and is the core dye for black denim fabrics. It can also be used for dyeing leather and paper. The suitable dyeing temperature is 90-95℃, the pH value of the dye bath is controlled at 9.5-10, and it supports dyeing processes such as dip dyeing, jigger dyeing and pad dyeing.

Product Types and Advantages

- Traditional Powdered Sulfur Black: Requires sodium sulfide for material dissolving, with more impurities, easy to cause dyeing cylinder difference, and prone to oxidation during transportation and storage.

- Environmentally Friendly Liquid Sulfur Black: No need for sodium sulfide for material dissolving, almost no impurities, higher absorption rate, and dry-wet rubbing fastness 0.5 grade higher than powdered products. It is suitable for dyeing denim yarns and gray fabrics, and has been widely used in Western industrial countries.

Production Process

Taking 2,4-dinitrochlorobenzene as raw material, it is hydrolyzed to sodium 2,4-dinitrophenolate under alkaline conditions, then vulcanized with sodium polysulfide solution, and finally prepared into finished products through oxidation, filtration and drying.

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