Dispersant-free Dyeing of Poly(lactic acid) Knitted Fabric with Temporarily Solubilized Azo Disperse Dyes

Poly(lactic acid) (PLA) is known for environmentally friendly material as it is derived from annually renewable crops and biodegradable. Dispersant-free dyeing of PLA fabric with three temporarily solubilized azo disperse dyes which contain beta-sulfatoethylsulfonyl group was investigated and their dyeing and fastness properties were compared with those of commercial disperse dyes. The temporarily solubilized azo disperse dyes were successfully applied to PLA fabric without the use of dispersant. The color yield on PLA fabric was dependent on dyebath pH and dyeing temperature as well. The optimum results were obtained at pH 7-8 and 110 degrees C. The dyes showed markedly higher color yield on PLA fabric when compared to commercial disperse dyes. Wash fastness was very poor to poor but light fastness was good. The COD levels of the dyeing effluent from the temporarily solubilized disperse dyes were considerably lower than those from commercial disperse dyes.