Cationic electrodeposition coating composition

摘要

A cationic electrodeposition coating composition comprising an amino-containing epoxy resin, a blocked polyisocyanate curing agent and a pigment; wherein the amino-containing epoxy resin is obtained by reacting an epoxy resin, a polyphenol compound, a dimer acid diglycidyl ester and an amine compound. Preferably the dimer acid diglycidyl ester contains linear, branched and/or cyclic hydrocarbon groups that altogether contain 10-150 carbon atoms. The dimer acid diglycidyl ester may be present in an amount of 0.1-50% by mass based on the solids content in the amino-containing epoxy resin. Preferably the composition further comprises an amine-added resin for pigment dispersion, being obtained by reacting an epoxy resin with an amine compound. Also disclosed is a coating method comprising immersing a metal article in a bath of said cationic electrodeposition coating composition to coat the metal article by electrodeposition. A coated article obtained by the coating method is also disclosed. The coating composition has improved throwing power, anti-GA gas pinhole properties and anti-corrosion properties.