CATIONIC RESIN AND CAPPED POLYISOCYANATE CURING AGENT SUITABLE FOR USE IN ELECTRODEPOSITION

摘要

PROBLEM TO BE SOLVED: To obtain a curable composition capable of carrying out electrodeposition without requiring a lead or a chrome rinse and having excellent resistance to corrosion by including a specified cationic resin and a specific curing agent and moreover including a specified amount of phenolic hydroxyl groups andβ-hydroxy ester groups. SOLUTION: This curable composition comprises (A) a cationic resin derived from a polyepoxide and containing cationic salt groups and active hydrogen groups selected from aliphatic hydroxyl, primary amino and secondary amino groups therein and (B) a fully capped polyisocyanate curing agent without containing free isocyanate groups. Moreover, the composition comprises phenolic hydroxyl groups in an amount of 0.02-1.0 milliequivalent based on 1 g of the resin solid andβ-hydroxy ester groups in an amount of 0.1-2.0 milliequivalents based on 1 g of the resin solid.