Method for making amine-modified epoxy resin and cationic electrodeposition coating composition

摘要

The present invention provides a cationic electrodeposition coating composition having good appearance of coated film and high throwing power, and a method for making an amine-modified epoxy resin used for the cationic electrodeposition coating composition. The present invention relates to a method for making an amine-modified epoxy resin comprised in a cationic electrodeposition coating composition comprising the steps of: providing a half blocked isocyanate by reaction of an isocyanate compound with a blocking agent, preparing a blocked prepolymer by reaction of the half blocked isocyanate with a polyol, forming an epoxy resin containing oxazolidone ring by reaction of the blocked prepolymer with a diglycidyl ether type epoxy resin, chain-extending the epoxy resin containing oxazolidone ring with at least saturated or non-saturated hydrocarbon group containing dicarboxylic acid, and modifying the chain-extended epoxy resin with an amine.