Internal anticratering agent for cathodic electrocoating compositions

摘要

An improved aqueous cathodic electrocoating composition having a binder of an epoxy-amine adduct and a blocked polyisocyanate crosslinking agent; wherein the improvement is the incorporation of an anticrater agent which is a polyoxyalkylene diamine having a number average molecular weight of about 700-5,000 by reacting it with the epoxy resin of the epoxy-amine adduct; wherein the amine to epoxy equivalence ratio of amine groups of the polyoxyalkylene diamine to epoxy groups of the epoxy resin of the epoxy amine adduct is within the range of 0.01-0. 90 to 1 and the resulting epoxy amine adduct has a number average molecular weight of about 1,500-20,000; where the above molecular weights are determined by Gel Permeation Chromatography (GPC) using polystyrene as the standard.