HDI/IPDI对水性聚氨酯及胶膜性能的影响

采用预聚体分散法制备了一系列固含量为50%的水性聚氨酯(WPU)，并通过傅里叶红外光谱(FT-IR)、粒径分析仪、X射线衍射(XRD)、差示扫描量热分析(DSC)、拉力试验机等仪器进行表征，研究了HDI/IPDI摩尔比对WPU的乳液性能和胶膜结晶性能、力学性能、耐水性能，以及基材EVA/PVC粘接性能的影响，分析了不同摩尔比的HDI/IPDI和粘接时间与WPU胶黏剂对EVA/PVC粘接性能的关系。研究发现，随着HDI/IPDI摩尔比增加，水性聚氨酯的乳液性能、软硬段的结晶性都得到提高，而胶膜拉伸强度呈先增大后减小的趋势，断裂伸长率则先减小后增大。所有WPU胶膜都有很好耐水性，胶膜吸水率都在5.0%（质量）以下。粘接实验结果表明，WPU胶黏剂对EVA/PVC具有优异的粘接性能，24 h后可对基材产生界面破坏，随着HDI/IPDI摩尔比增加，胶黏剂的粘接强度增大。当HDI/IPDI=7∶1时，水性聚氨酯的综合性能最好。

Effect of HDI/IPDI mole ratio on properties of waterborne polyurethane and its film

A series of waterborne polyurethanes(WPUs)with 50% solid content were prepared through a prepolymer process.The properties of the dispersion and its film were characterized by Fourier transform infrared spectroscopy(FT-IR),particle size analyzer,X-ray diffraction(XRD),differential scanning calorimetry(DSC)and tensile test machine.The influence of HDI/IPDI mole ratio on the properties of waterborne polyurethane dispersion,its film and the adhesive strength to EVA/PVC substrate were studied.The relationship between adhesive strength and time was analyzed.The results indicated that the WPU dispersion,crystallinities of soft segment and hard segment were improved with increasing HDI/IPDI mole ratio,while tensile strength of films significantly increased and then showed a small decrease,and the elongation at break increased first,then decreased.WPU films exhibited excellent waterproof performance,and the amount of water absorption was as low as 5.0%(mass).The test result showed that all WPUs prepared exhibited outstanding adhesive strength to EVA/PVC substrate,and the joint failure of EVA/PVC substrates was all caused by the failure of interface after 24 h.With increasing mole ratio of HDI/IPDI,the adhesive strength of adhesive to EVA/PVC substrate increased,and when the mole ratio of HDI/IPDI was 7∶1,the performance of WPU adhesive was the best.