Study On Preparation Of Aqueous Polyurethane Dispersion And Application On Shrink-resisting Of Wool

Aqueous reactive polyurethane is optimum agent used in shrink-resisting of wool as a non-chlorine finishing agent. When it was applied, the heat can free the NCO group to react with the functional group of the wool, forming crosslinking structure on the surface and achieving the anti-felt effect. This process is simple and environmental but restricted in the application because of the stiff handle of the fabric after treatment. The anionic self-emulsified polyurethane compounded with aqueous reactive polyurethane is used as a shrink-resisting finishing agent to improve the handle.Prepolymer mixing process was one of the common methods to prepare the polyurethane used with polyester and aromatic isocyanate. In this paper, aliphatic isocyante-isophorone diisocynate (IPDI) and polyether with large molecular weight, by incorporating dimethylol propionc acid (DMPA) into the prepolymer backbone were used to synthesis aqueous polyurethane.The aqueous polyurethane formulating system is complicated for water is used as a medium. The ratio of NCO/OH, the content of DMPA, neutralization and chain extension all impact dispersion particle size, viscosity, molecular weights, tensile-strength, elongation and water resistance of film. A series of recipes were studied and all factors have their optimal value. DSC analyses of polyurethane film with different chain extension present that the transition temperatures increase with the higher degree of chain extension. TGA analyses of polyurethane film with different chain extension show that the initial decomposition temperature of the film increases slightly with increase of degree of chain extension. GPC analysis is also applied to show the increase of molecular weight with the chain extension. All these factors were taken into consideration, so the optimal recipe was that the ratio of NCO/OH was 1.5, the content of DMPA 7%, neutralization 100% and the degree of chain extension 90%.The synthesized anionic self-emulsified aqueous polyurethane compounded with the reactive polyurethane was used as shrink-resisting agent of wool. The anti-felt performance of the finished wool achieved the "Machine Wash" criterion which was established by IWS (International Wool Secretary), and the handle of fabric was improved, the yellowing was decreased. The compounded agent was used in factory and the best recipe was confirmed. The finished fabrics were tested by ITS, and all targets achieved the AATCC 150-2003, Test No. (1) IIB criterion.