Modification of epoxy resins with urethane prepolymer for electronic encapsulation

摘要

A modified epoxy resin is prepared by mixing an isocyanate terminated urethane prepolymer with an epoxy resin in reactive conditions. The modified epoxy resin has a low internal stress when it is cured due to the flexible backbone of the urethane prepolymer incorporated therein, and has a high glass transition temperature due to a rigid oxazolidone structure formed via the epoxy ring opening with the isocyanate groups, and thus is useful as an electronic encapsulant.