Aftertreatment of polyester fabric dyed with temporarily solubilised disperse dyes

Temporarily solubilised disperse dyes derived from aminophenyl-4-(beta -sulphatoethylsulphone) are exhausted on the polyester fibre mostly in the vinylsulphone form and to a lesser extent as their hydroxyethylsulphone analogues. After dyeing, to remove the unexhausted dyes on the polyester fibre, sulphite anions were added to the dyebath. The vinylsulphone residue of the dye was attacked by the sulphite anion via an addition reaction converting the dye into a soluble derivative, which then had little affinity for the polyester fibre. The effect of sodium sulphite on the conversion of the dye was investigated using HPLC. The wash and rub fastness properties of the dyed fabric aftertreated with sodium sulphite were similar to those obtained with reduction clearing.