Reactive dyeing systems for wool fibres based on hetero-bifunctional reactive dyes. Part 3: Application of specially prepared hetero-bifunctional and related model dyes on wool

Six model dyes and two colourless compounds having different functionality were prepared, and their dyeing properties and the effect on inhibiting wool set and fabric hygral expansion were investigated. It was found that hetero-bifunctional reactive dyes are more efficiently able to bond to wool fibre regardless of dyebath pH than mono-functional (monochlorotriazine) reactive dyes. Also, dyeing wool fabrics with hetero-bifunctional dyes and colourless compounds containing vinylsulphone residues clearly decreased the hygral expansion and inhibited permanent set, when compared to dyeings produced with mono-functional reactive and non-reactive dyes. The improvements in the two physical properties were found to increase with increased reactive dye or reactive compound concentration. Dyes containing a beta-sulphatoethylsulphone group diffused more evenly than dyes containing a preactivated vinylsulphone group. It was also shown that the number of sulphonate groups in a dye molecule affected migration properties.