关键词: 水性聚氨酯, 结晶性能, 力学性能, 粘接性能

Abstract: 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.

Key words: waterborne polyurethane, crystallinity, mechanical property, adhesive property