Preparation And Performance Of Waterborne Polyurethane For Road Casting And Glove Coating

Traditional polyurethane runway is dominated by toluene diisocyanate(TDI)type,which often contain free TDI and volatile organic solvents.These residues not only do harm to health but destroy the environment also.Therefore,in order to solve this problem,this article uses low toxicity isophorone diisocyanate(IPDI)and polytetrahydrofuran(PTMG)as the main raw materials.By adjusting the raw material ratio and introducing functional monomers,a WPU system with high mechanical properties is prepared for road casting.Based on this,its water and alcohol resistance properties are further improved for use in the coating of medical gloves,thereby replacing the powder lubricant used in traditional medical gloves to increase the wearability of the gloves.The specific research contents and conclusions are as follows:(1)One component WPU emulsion with PTMG and IPDI as main raw materials was prepared by acetone method.The synthesis of the target product was confirmed by fourier transform infrared(FT-IR)and ultraviolet visible spectrophotometer(UV).The effects of initial R value,the amount of hydrophilic chain extender 2,2-dimethylolpropionic acid(DMPA),the type and amount of crosslinking agent on the mechanical properties of film were investigated.It was found that when the initial R value was kept at 2.4,the amount of DMPA was 5%,and the amount of epoxy resin E51 was 9%,the film had the best mechanical properties,its tensile strength was 19.4MPa and breaking elongation was 1203%.Diethylene glycol amine modified E51(DGA@E51)It has more excellent aging resistance.When its level was 9%,the tensile strength and breaking elongation were 10.3 MPa and 1215%respectively.(2)Two different molecular weight dihydroxy silicone oils(DHS)were used to modify the emulsion to introduce hydrophobic siloxane segments to improve the water and alcohol resistance of the coating.FT-IR and nuclear magnetic resonance spectroscopy(NMR)confirmed that DHS had been successfully connected to the molecular chain of WPU.Scanning electron microscopy(SEM)showed that DHS affected the degree of microphase separation of WPU.It was found that the addition of two molecular weight DHS can improve the mechanical properties,heat resistance,and water contact angle of the coating.When the molecular weight of DHS was 850(DHS-850),the molar ratio of DHS-850 and PTMG was 1:4,and the amount of epoxy resin HEP was 3%,the water contact angle was 87.3°,the water absorption rate was 7.4%,and the water and alcohol resistance of coating was Grade 3.The comprehensive performance of the paint film was good.(3)The solvent resistance of the coating was improved after the WPU was slightly crosslinked by the introduction of macromolecular trihydroxy propylene oxide(N-330).After controling the amount of N-330,small molecular crosslinking agents glycerol(GI),pentaerythritol(PER),and silicone monomer DHS-850 were added to prepare a second order crosslinked silicone modified WPU.When the molar ratio of BDO and PER was 1:2,and the molar ratio of DHS-850 and PTMG was 1:6,the water contact angle of the coating was 94.5°,and the water and alcohol resistance properties reached Grade 1.The smoothness and feel of the coating are the best.The tensile strength of film reaches 7.39 MPa,and breaking elongation was 1178%.