Kathodische Elektrotauchlackierungszusammensetzung die ein mit primärem Amin kettenverlängertes Epoxydharz enthält

摘要

An improved aqueous cathodic electrocoating composition of an aqueous carrier having dispersed therein a film forming binder of (1) an epoxy-resin amine adduct and (2) a blocked polyisocyanate crosslinking agent; wherein the improvement is an epoxy resin amine adduct which is a reaction product of an epoxy resin and a polyhydric phenol which is chain extended with a primary amine to form a chain extended epoxy resin having epoxy end groups and an equivalent amine to epoxy ratio is 1-10 to 4-10 and wherein the epoxy end groups of the resin are reacted with a ketimine and/or a diamine and the resulting chain extended epoxy resin has an epoxy equivalent weight of about 700 - 2,000 and is neutralized with an organic or inorganic acid; wherein the electrocoating composition has improved throw power and forms coatings that have improved corrosion resistance in comparison to conventional electrocoating compositions formed from epoxy resins extended with conventional diamines or polyols.