One component photo-curing agent for epoxy resins based on multifunctional photobase generators containing oxime-urethane groups

In order to develop a one-component photo-curing system for epoxy resin, the photo-crosslinking reactions of the diglycidyl ether of bisphenol A (DGEBA) in the presence of a multifunctional photobase generator (PBG) containing oxime-urethane groups were studied. The cross-linking of DGEBA films and adhesion properties of DGEBA formulations containing the PBG and benzophenone increased with irradiation dose, post-exposure baking (PEB) time, PEB temperature, and the number of oxime-urethane groups in the PBG. A synergistic effect was observed between the PBG and a base amplifier on the film cross-linking of DGEBA. A trifunctional PBG containing oxime-urethane groups was found to be the most efficient PBG in terms of the photo-crosslinking and adhesion properties of the DGEBA-based formulations. Moreover, the devised formulations, including the PBG and benzophenone, were stable for at least 1 month at room temperature. The photocuring system developed in this study appears to offer a one-pack epoxy resin curing system with practical useful properties. Copyright (C) 2009 John Wiley & Sons, Ltd.