Soft segment-containing modified epoxy resin and cathodic electrodeposition paints containing same

摘要

A diglycidyl ether epoxy resin is reacted with a blocked prepolymer having a soft segment and an asymmetric bisurethane having a first urethane group with a lower alkanol and a second urethane group with a monohydroxyl compound capable of enhancing thermoflowability. The product is then reacted with a cationic active hydrogen compound such as amines to open the remaining epoxy rings. The modified epoxy resin thus produced is dispersed in an aqueous medium containing a neutralizing agent together with a blocked polyisocyanate crosslinker to give a cathodic electrodeposition paint having improved impact strength and thermoflowability.