The dyeing of silk Part 4 heterobifunctional dyes

The exhaustion and fixation of three commercial aminochlorotriazine/masked vinylsulfone dyes were both pH- and temperature-dependent Optimum dye fixation was obtained at pH 8 as a corollary of a high number of nucleophilic -NH2 groups in the fibre high conversion of the masked form of the dye to the reactive VS variant as well as reaction with OH-containing amino acid residues The marked temperature-dependence of dye fixation achieved in the pH range 3 to 9 demonstrated the importance of kinetic factors in dye fibre reaction The wash-off method used was very effective in removing unfixed/hydrolysed dye from the silk fabric and as a result the dyeings displayed very good fastness to washing at 40 degrees C (C) 2010 Elsevier Ltd All rights reserved