Abstract
Recently, phosphoric ester compounds have been used as non-halogen flame retardants for epoxy resins. This results in a problem that the phosphoric esters often inhibit the thermosetting of epoxy resins. In this study, to solve this problem, the thermosetting inhibition mechanism was clarified by 1H-NMR and GC-MASS analysis of products obtained from the reaction of epoxy compound/imidazol/phosphoric ester. As a result, it was found that phosphoric ester was first decomposed by a trace amount of hydroxyl group to generate free hydroxyl groups. Then the free hydroxyl group reacts with epoxy compound to generate alcohol, which decomposes phosphoric ester again. In this way, thermosetting of epoxy resin is probably inhibited.
