Preparation And Characterization Of IPDI Hydrophilic Polyisocyanate

Currently people draw much attention to the two-component waterborne polyurethane because of its excellent performance and low volatile organic compound(VOC),especially in the study of water dispersible polyisocyanates.The chemical hydrophilic modification of polyisocyanates were proceeded by non-ionic modifiers.This method promoted the development of the modification of polyisocyanates by polyether polyols.But the polyisocyanates synthesized by this method has low average functionality,and the thin film received by polyisocyanates and aqueous polyurethane polyol dispersion has low cross-linking degree and chemical resistance,so the final performances of the materials are not satisfied.Based on the current preparation methods,the water dispersible polyisocyanates were synthesized by isophorone diisocyanate(IPDI)trimer and 3-hexanaphthene amino-1-propane sulfonic acid(CAPS)as the main raw materials in this paper.The hydroxyl component,which were prepared by polyester polyols,isophorone diisocyanate(IPDI)and dimethylolbutanoicacid(DMBA),and the water dispersible polyisocyanates were used to synthesize the polyurethane hard thin film with water-tolerance,solvent resistance and excellent mechanical properties.he chemical structures of the hard thin film were characterized with the infrared spectroscopy(FI-IR)and nuclear magnetic resonance(1H-NMR).The influences of percentages of CAPS composition on the performances of the water dispersible polyisocyanates,solid content,-NCO-OH equivalent ratio and the percentages of DMBA composition on the performances of aqueous polyurethane polyol dispersion were studied.The universal mechanical testing machine were used to characterize tensile properties.The results show that:the hydrophilic sulfonic groups of CAPS are successfully introduced into the molecular chains of polyisocyanates,and when the IPDI trimer/CAPS is 4:1,the product has an excellent solubility and stability.When solid content is 35%and the percentages of DMBA composition is 4.5%,aqueous polyurethane polyol dispersion has an excellent comprehensive performances.When the-NCO/-OH molar ratio increases,film-forming property becomes better,the cross-linking density increases,the water resistance property increases,the tensile strength increases,and the elongation at break decreases.When-NCO/-OH equivalent ratio is 2:1,the tensile strength of the thin film is 12.72MPa and the elongation was 130.6%,meanwhile has a lowest water absorption.