cationic resin and treating agent for a polyisocyanate suitable block electrodeposition.

AVAILABLE electrodepositable composition comprising: (A) an ungelled cationic resin THIS DERIVED FROM A polyepoxide and which contains in the resin molecule cationic salt groups and active hydrogen groups selected from hydroxyl and amino ALIPHATIC PRIMARY AND SECONDARY; And present as a separate component; (B) a curing agent polyisocyanate completely covered CONTAINING ISOCYANATE GROUP SUBSTANTIALLY FREE NO. COMPOSITION ELETRODEPOSITABLE contains from about 0.02 milliequivalents 1.0 PHENOLIC HYDROXYL GROUPS per gram of solid RESIN, and from about 0.1 to 2.0 milliequivalents of ester groups per gram of solid BETAHIDROXIDO RESIN. The composition provides excellent resistance to corrosion when ES electrodeposited steel substrates, and requires LEAD IN THE DESIGN OR THE USE OF CONVENTIONAL rinsing CHROME FOR pretreating the steel substrate prior to electroplating.