Syntheses and dyeing properties of novel water‐soluble reactive sulphur black dyes

Abstract

AbstractThe practical application of a sulphur black dye relies on its ability to dye cotton fibres with pure black colour and maintain the colour with high light fastness. Here, we report a synthesis method to prepare a novel water‐soluble reactive sulphur black dye. The approach involves the reduction of CI Sulphur Black 1 to its leuco form and subsequent reaction with a water‐soluble intermediate containing reactive groups synthesised from amino acid and cyanuric chloride. The optimal carboxyl and reactive group content of the water‐soluble reactive sulphur black dye is 141 mmol/100 g, and the water solubility can reach 92 g/L. The fixation of the reactive sulphur black dye on cotton reaches 89% in a pad dyeing process without using sodium sulphate. The reactive sulphur black dye can achieve a light fastness of grade 6‐7, a dry rub fastness of grade 4 and a wet rub fastness of grade 2, comparable or higher than the conventional CI Sulphur Black 1. The dyeing results showed that the novel water‐soluble reactive sulphur black dye has excellent performance and good application prospects.