UV-curing behavior of unsaturated cyclohexanone formaldehyde resins with thiols

Numerous researches about the modification and application of cyclohexanone formaldehyde resins (CFR) have been conducted, few of them involve in the UV-curing of unsaturated CFR with thiols. Thus, CFR are synthesized using the rehydrated magnesium-aluminum hydrotalcite as the catalyst and double bonds are introduced by capping the chain ends with 5-norbornene-2,3-dicarboxylic anhydride. Through monitoring the conversion of double bonds with FTIR, the UV-curing behavior of unsaturated CFR in the presence of pentaerythritol tetra (3-mercaptopropionate) is studied. The results show that the conversion of double bonds can reach to 64.1% at 0.66 mW cm(-2) of UV light intensity when the molar ratio of double bonds to sulfhydryl groups is 1:1 in the presence of benzoin dimethyl ether (1% of molar amount of double bonds). Considering the similarity between UV-curing of thiols-double bonds and thermo-curing of amine-epoxy, one diffusion controlled kinetics model is derived and it shows good fitness. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48420.