C.I. Sulphur Blue 7

PHYSICAL DESCRIPTION: Black crystalline solid. (NTP, 1992)

Using o-toluidine and phenol as raw materials, firstly nitrosate phenol, then dissolve o-toluidine in sulfuric acid and condense with p-nitrosophenol to obtain intermediate 3-methyl-4-amino-4'-hydroxydiphenylamine (I), then vulcanize (I) with sodium polysulfide, oxidize, filter, and dry to obtain the finished product (II). 1 part of phenol, 1.36 parts of sodium nitrite, 0.86 parts of sulfuric acid, and 4.5t of water are subjected to nitrosation reaction at 12°C to obtain p-nitrosophenol. Dissolve 1 part of o-toluidine in 4.3675 parts of sulfuric acid, then add 1.0149 parts of p-nitrosophenol, heat up to 30°C, condense for 1h to obtain intermediate (I). Heat the above-mentioned intermediate (I) with 1 part of sodium sulfide, 2.75 parts of sulfur, and water to 110-111°C for 30 hours to carry out vulcanization. Then add water to dilute, heat up to 88-90℃, oxidize with air for 14h to obtain the product (different proportion of sulfur content in sodium polysulfide, different curing temperature, different color and light of the obtained product. The proportion of sulfur content increases, the temperature rises, and the product color is better Red and bright, so there are different trade names. For example, sulfur blue BN with cyan light, sulfur blue BRN with cyan red light, sulfur blue RN with red light, etc.).

Sulfide blue BRN is mainly used for dyeing cotton, hemp, viscose fiber, vinylon and its fabrics. It is the main color dye for navy blue and has a bright color. It can also be dyed with yellow dye in dark gray.