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

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