Sulfur Blue BRN CAS No.: 1327-57-7 C.I. Number: 53440 (Sulfur Blue 7)

· CAS No.: 1327-57-7

· EINECS No.: 215-483-5

· C.I. Number: 53440 (Sulfur Blue 7)

· Molecular Formula: C₁₃H₁₄N₂O (or as sulfur complex)

· Appearance: Blue-violet powder, insoluble in water, soluble in sodium sulfide solution producing a green-gray color

Product Overview

Sulfur Blue BRN is a synthetic sulfur dye primarily used for dyeing cellulosic fibers such as cotton, linen, viscose, and vinylon. The "BRN" designation indicates a bluish-red shade with violet undertones, positioned between the BN (greenish-blue) and RN (reddish-blue) variants.

Dyeing Mechanism

The dye is insoluble in water but becomes soluble after reduction in an alkaline sodium sulfide (Na₂S) bath, forming a leuco compound that penetrates the fiber. Subsequent oxidation (by air or oxidizing agents) reverts the dye to its insoluble form, locking it within the fiber structure. This process provides excellent wash fastness.

Applications

Sulfur Blue BRN is widely used for producing navy blue and deep grey shades on cotton yarns, denim, workwear, and industrial textiles. It can be combined with yellow dyes to achieve dark grey hues.

Typical Specifications

· Strength: 150% (typical commercial grade)

· Moisture content: ≤6.0%

· Insoluble impurities in Na₂S: ≤2.0%

· Free sulfur content: ≤1.0%

Packaging

Standard packaging is 25 kg per iron drum, kraft bag, or fiber drum.

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