Preparation and photochemical properties of PEG based alpha-hydroxyalkylphenone photoinitiator

A novel emulsified photoinitiator (named as OP10-IPDI-2959) was prepared by the reaction of isophorone diisocyanate (IPDI) with 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Ir-2959) and nonylphenol polyoxyethylene ether (OP-10). The structure of OP10-IPDI-2959 was characterized by FT-IR, 1H NMR, UV–vis and high-resolution mass spectrometry. The photochemical behavior of OP10-IPDI-2959 was investigated through the photolysis and polymerization of neopentyl glycol diacrylate (NPGDA), mixture of epoxy acrylate resin and 1,6-hexanediol diacrylate (HDDA). Under irradiation of UV light, the OP10-IPDI-2959 has similar photochemical properties with the Ir-2959. Combined with benzophenone, the photoinitiated rate of OP10-IPDI-2959 is higher than that of Ir-2959. The polyoxyethylene fragment of OP10-IPDI-2959 is not only an alternative to toxic amine as hydrogen donor, but also a hydrophilic unit for interface between oil and water. The OP10-IPDI-2959 can effectively emulsify the epoxy acrylate resin and 1,6-hexanediol diacrylate mixture to form low viscosity emulsion. Compared with Ir-2959, OP10-IPDI-2959 has good photoinitiation activity, lower migration and good water emulsification performance.