Composition and process for multi-purpose treatment of metal surfaces

摘要

A multipurpose treatment composition for metal surfaces comprises phosphate ions, fluorometallate ions, water soluble polymers containing substituted aminomethylene moieties bonded to benzene rings which also have an oxygen atom bonded to another carbon atom in the same ring, and a distinct kind of film-forming polymer. The compositions are free from chromium and other heavy metals that cause serious pollution problems in some prior art treatment compositions. Coating layers formed in a process according to the invention are effective for at least three different purposes: increasing adhesion of and corrosion protection from subsequently applied paints or other protective coatings with a largely organic matrix; without any subsequently applied protective coating, providing at least temporary protection against staining and development of white rust on zinc or zinc alloy surfaces treated in a process according to the invention, and providing sufficient lubricity to permit roll forming of sheet metals treated in a process according to the invention without the need for additional liquid lubricants such as oil.