Radical induced Cationic Frontal Polymerization

Epoxy resins are widely used in coatings, adhesives and casting compounds. Common curing techniques for epoxy resins involve the addition of anhydride or amine based hardeners and thermal curing of the formulation. A different approach is the so called radical induced cationic frontal polymerization (RICFP) in which a cationic photoinitiator (photoacid generator) is added to the epoxy resin, which produces acid upon radiation with UV light. Additionally a thermal, radical initiator is mixed in the formulation that provides the shadow curing abilities. The big advantages of RICFP are the very low energy consumption of the curing process and the short curing times. In this paper we present the first bubble-free system on the base of bisphenol-A-diglycidylether (BADGE), a very common epoxy resin in industrial applications. Also a proof of concept for the usage as adhesive for electrical insulating mica sheets will be given.