Preparation of Cationic Polyurethane Dispersion and Its Effectiveness as Denim Dye Fixing Agent

The issue encountered by the textile industry is that the colours are fading off, particularly in denim fabric, by constant washing, so fixing agent is needed to enhance the colour fastness of the denim fabric. Polyurethane is one of the promising types of nonformaldehyde dye fixing agents. It has good film covering properties and allows air permeability. In this study, cationic polyurethane dispersions (CPU) were syntheses and applied as fixing agent for sulphur dye denim fabric. Different formulation of CPU were synthesized using isophorone diisocyanate, different molecular weight of polyols, and tertiary amine. Formulated CPU were then analysed using FTIR, zeta potential analyser and viscometer. Zeta potential obtained was in the range of +8.1 mV to +41.7 mV indicates that some of the CPU particles tend to agglomerate and some are stable. After fixing treatment, colour fastness to crocking of the treated fabric has improved. Surface morphology changes were determined by SEM and it shows that smooth finishing fibre surface was obtained in treated black denim fabric.