Electrocoat composition and process replacing phosphate pretreatment

Abstract

An aqueous coating composition comprises a metal oxide selected from the group consisting of bismuth oxide, vanadium oxide, manganese oxide, cobalt oxide, zinc oxide, strontium oxide, yttrium oxide, molybdenum oxide, zirconium oxide, lanthanum oxide, oxides of the lanthanide series of elements and combinations thereof and an electrodepositable binder, the binder comprising (a) a phosphorous-containing group in which X is a hydrogen, a monovalent hydrocarbon, an alkyl group such as an aminoalkyl group, or an oxygen atom having a single covalent bond to the phosphorous atom, and each oxygen atom has a covalent bond to a hydrogen atom, an alkyl group, an aryl group, an alkylaryl group, an arylalkyl group, or the resin, with the caveat that at least one oxygen atom has a covalent bond to resin; (b) a carboxylate group separated by from 2 to 4 carbons from an ester group; and (c) a tridentate amine ligand. The coating composition can be electrodeposited on a metal substrate to provide superior corrosion resistance.

Dependencies are inferred from the claim text.