Study on the Synthesis and Properties of Acrylated Epoxy Prepolymer Used for the UV Curable Coating

Abstract: UV梒urable epoxy acrylates were prepared by reacting epoxy resin with acrylic acid in the presence of onium salt. The effects of synthesis condition, such as the kinds and concentration of catalyst, the reactive temperature and time, the feeding ratio, etc.on synthesis reaction and product properties have been discussed. And the observe active energy of reaction has been calculated. The photocuring process was monitored by measuring the variation in double bond content with IR spectrometry. We also used chemical titration to mea- sure the double bond conversion rate. The initiating efficiency of different pho- toinitiators was examined. When radiation curable coatings was exposed to UV in air, the curing rate increases approximately linearly as the concentration of photoinitiator increases at first, but increases sharply at a certain concentra- tion. In this paper, it can be interpreted as being due to the diffusing and ex- hausting of oxygen in UV coating. The effects of crosslinking agent on gela- tion extent~ attaching strength,.strike resistance have also been studied. We found that the crossliking degree is mainly depended on the ratio of prepolymer to crosslinking agent. We also found the distance from UV lamp to sample and the thickness of sample have great effects on curing rate, and the speed of pho- tocuring reaction and the final conversion rate of coatings can be increased with raising temperature…
Key words: UV curing; acrylated epoxy prepolymer; onium salt; photoinitia- tor; free radical polymerization; infrared spectrometry

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