Abstract:  In order to improve the mechanical and chemical properties, especially the solvent resistance of the cast films formed from normal waterborne polyurethane (PU) dispersions, a novel ultraviolet (UV)-curable epoxy and acrylate-modified waterborne polyurethane dispersion (UV-EP-AC-WPUD) and its film with high crosslinking density and excellent film properties were prepared and studied.4% epoxy resin E-20 was introduced in PU chain by grafting reaction between epoxy resin and polyurethane prepolymer terminated with the –N=C=O group.The C=C bond was introduced in PU chain by the chain-extending reaction of —NCO in polyurethane prepolymer with two hydroxyl vinyl monomers PEDA and single-hydroxyl vinyl monomers PETA, and the obtained maximum C=C content was up to 4.65 meq·g-1. 3% photoinitiator Irgacure 2959 was used to initiate the polymerization of C=C bond in cast films, and the gel content of the UV-EP-AC-WPUD films could reach up to 91% after 12 s UV-radiation, which meant the polymerization rate and crosslinking rate of C=C bond was high, and the obtained UV-EP-AC-WPUD film was highly-crosslinked and insoluble in solvent.The water absorption, solvent resistance, gel content, pendulum hardness and tensile strength of the cured film were studied, and Fourier transform infrared spectroscopy (FTIR) analysis and film study results showed that the UV-cured EP-AC-WPUD films including epoxy resins and hydroxyl-containing vinyl monomers had excellent mechanical and chemical properties. Thermo gravimetric analysis (TGA) also indicated that the thermal stability of the film was improved significantly.

Key words: UV-curable, waterborne polyurethane, epoxy, crosslinking density, photoinitiator

摘要： 合成了一种新型的具有高交联密度和优异涂膜性能的环氧树脂和丙烯酸酯同时改性的紫外线（UV）固化水性聚氨酯（UV-EP-AC-WPUD）。通过环氧基团与以异氰酸酯基团（-N=C=O）封端的聚氨酯预聚体之间的反应引入质量分数为4%的环氧树脂E-20。同时，通过聚氨酯链的-N=C=O与二元丙烯酸酯（PEDA）以及季戊四醇三丙烯酸酯（PETA）的羟基之间的反应引入碳碳双键（C=C），C=C的含量达到4.65 meq·g-1。 质量分数为3%的光引发剂Irgacure 2959被用于引发涂膜中C=C的聚合，涂膜的凝胶含量在12 s UV辐射之后达到91%，意味着C=C的聚合和交联速度快，同时所得到的涂膜的交联度非常高，不溶于溶剂丙酮，测试表明环氧树脂和两种丙烯酸酯单体已经成功嵌入聚氨酯链中，涂膜具有优异的力学性能和化学性能。

关键词: 紫外线固化, 水性聚氨酯, 环氧树脂, 交联密度, 光引发剂