| UV-curable coatings as an environmentally friendly coating have been developed rapidly owing to its characteristics of high efficiency, energy saving, and low VOC in recent years. Epoxy acrylate has so excellent characteristics, such as curing speed, high hardness, and good adhesion that it become the most widely used oligomer in UV-curable coatings. But bisphenol A epoxy acrylate has some disadvantages such as high viscosity and poor flexibility. In order to improve its comprehensive performance, this paper, based on the nonisocyanate polyurethane (NIPU) reaction technology, studied the modified epoxy acrylates respectively from NIPU-230 modified epoxy acrylate and silane modified waterborne epoxy acrylate.(1) UV-curable epoxy acrylate modified by NIPU-230 was synthesized via the nonisocyanate polyurethane (NIPU) reaction with Jeffamine D-230 and ethylene carbonate generating aliphatic dihydroxyl compound (NIPU-230), subsequent esterification reaction partly with epoxy resin (E-51) and acrylated termination with acrylic acid (AA). The structure of NIPU-230 was characterized by Fourier transform infrared spectroscopy (FT-IR) and (nuclear magnetic spectroscopy)’H NMR. Effects of temperature, kinds and dosages of catalyst and time on the process of the reaction about NIPU-230 with E-51 were investigated. And the dosage of NIPU-230 on the oligomer coating performance impact was investigated. The results showed that the optimal synthesis conditions of NIPU-230 with E-51were as follows:Reaction temperature was 115℃, catalyst was tetra butyl ammonium bromide (TBAB), and the dosage of TBAB was 0.5%, reaction time was 3h. In comparison with unmodified epoxy acrylate, when n (NIPU-230):n (E-51) is 0.2, the viscosity of oligomer is as low as 4900 mpa.s (60℃), moreover, coating flexibility can be up to lmm. At this case, comprehensive performance of coating is the best.(2) A reactive silane that can be used for UV-curable system was synthesized via the nonisocyanate polyurethane (NIPU) reaction with ethylene carbonate and (3-Aminopropyl) triethoxysilane, and the esterification reaction with maleic anhydride (MA). UV-curable waterborne epoxy acrylate modified with silane was synthesized by introducing the silane into the resin structure and maleic anhydride into the resin branched chain. The structure of reactive silane was characterized by FT-IR and 1H NMR. Effects of the dosage of maleic anhydride, the neutralizing agent, the neutralization degree, and the reactive silane with different concentrations (1%, 3%,5%) on water-soluble and stability waterborne epoxy acrylate were investigated. Then water resistance and heat resistance of coating were further studied. The results showed that in these conditions that the maleic anhydride and epoxy mole ratio was 0.7, neutralizer was trimethylamine, neutralization degree was 100%, the reactive silane dosage was 3%, the waterborne epoxy acrylate modified with silane has good water solubility and stability. It concluded that the coating of waterborne epoxy acrylate modified with silane has several advantages as the hardness of 4H, the flexibility of 1mm. With the increase of silane, water contact angle of coating was rising and the water absorption was falling. The result of TGA showed that the thermal stability rose with the increase of silane... |
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