Verfahren zur Herstellung eines zusammengesetzten Films auf einem metallischen Substrat

摘要

A film forming process which imparts excellent formability, corrosion resistance and paintability to the surface of aluminum or aluminum alloy plates or aluminum-plated sheet steel. A process for forming composite film on the surface of aluminum or aluminum alloy plates which comprises preliminarily treating the surface with a chromating liquid to form a chromate film on the surface, and then coating on the chromate film an organic macromolecular resin composition comprising urethane resin and at least one kind of resin selected from polyester resin and epoxy resin, a wax as a lubricating additive and further a silica sol, followed by drying, to form a film layer.