Electrodeposition baths containing organic phosphorous-based compounds

摘要

Disclosed is an improved electrodeposition bath composition which is comprised of a resinous phase dispersed in an aqueous medium, the resinous phase comprising an active hydrogen group-containing cationic electrodepositable resin and a curing agent having functional groups reactive with the active hydrogen groups of the resin. The improvement comprises the inclusion in the electrodeposition bath composition of an organic phosphorous-based compound of specific structures. The electrodeposition bath compositions provide excellent corrosion resistance to electrocoated substrates, particularly untreated steel, and reduced corrosivity of the acidic cationic electrodeposition bath to steel equipment and pipes. Also disclosed is a method of electrocoating a conductive substrate using the improved electrodeposition bath compositions of the invention. Metallic substrates coated by this method are also disclosed.