Study On Synthesis And Performance Of Waterborne Polyurethane Containing Silicane Chain-Segment

With the great development of waterborne polyurethane (WPU) industry, the researchers give more and more attention to the modification of WPU in order to improve its performance. Our group has engaged in the research and development of WPU for several years. We used it as a finishing agent to improve the crocking fastness (especially the wet-crocking fastness) of pure-cotton fabrics dyeing with reactive dyes in deep-shade. But the handle of the finished fabrics was stiffer. So in this paper we modified WPU with the silicane chain-segment. We hope that the agent would improve the wet-crocking fastness and the handle of the finished fabrics at the same time.In this paper, we synthesized WPU by the method of self-emulsification. Firstly, the pre-polymer was prepared with polyethylene glycol (PEG) and toluene dissocyanate (TDI). Then the chain-extending reaction occurred with mixed chain-extending agents containing the tertiary amine chain-extending agent, the silicane chain-extending agent and the hard chain-segments regulator. We obtained a series of products by changing the silicane chain-segment contents in the mixed chain-extender. It was found that along with the increasing in the molecular weights and contents of silicane chain-segment, the viscosity of products and particle size of aqueous dispersion were increased and the stability was decreased. The pH would influence the aqueous dispersion performance. Along with the drop of pH, the particle size decreased and the stability increased.The products were used as finishing agents to finish three kinds of pure-cotton fabrics (plain cloth, sanding cloth and corduroy cloth) dyeing with three colour (red, blue ang black) reactive dyes in order to improve the crocking fastness. One kind of WPU products was chosed according to the finishing effect. The influencing factors were analyzed in the using time and the reasonable process conditions were confirmed including padding or impregnation method. The treated fabrics featured good ranking of wet-crocking fastness, and the effect wasn’t reatricted with different kinds of reactive dyes and pure-cotton fabrics. Meanwhile, the influence of the finishing agent to other fastnesses, such as color change, color fastness to washing, perspiration, water, etc., was small. The breaking strength and elongation rate were decreased, and the tearing strength and wrinkle recovery angle were increased.In the part of handle, the treated fabrics finished by the agent containing silicane chain-segment had droping bending stiffness and lower surface friction properties comparing with the fabrics treated by the agent without silicane chain-segment. It proved that the finishing agent used in this paper could improve the handle of treated fabrics remarkably.