Epoxy resin with dibasic acid (methyl ester)/ethyleneurea modifier

Acyl-ethyleneurea terminated compounds based on the reaction of ethyleneurea with dibasic acids or methyl esters of dibasic acids or cyclic anhydrides are useful as modifying agents, cure accelerators and blocking agents with tertiary amine catalysts for epoxy resins. As epoxy modifiers, they react with epoxy resins at 120 degrees C. without a catalyst to produce modified epoxies having increased viscosity and increased reactivity and solvent power. When combined with a suitable tertiary amine catalyst, they are useful as cure accelerators at a low cure temperature of about 80 degrees C. When combined with a tertiary amine, they form complexes which provide superior latency of the epoxy-hardener mixture at 20 degrees C. Heat-curable epoxy-based compositions treated with the materials of the invention and processes whereby the various novel compositions of the invention are made, are also described.