| abstract |
(57) [Problem] To provide a method for forming a rust-preventive coating film having high corrosion resistance and being unaffected by organic impregnating agents on the surface of an aluminum die-cast member constituting a drive unit for an outboard motor and the like. To provide. SOLUTION: The surface of an aluminum die-cast member is pre-treated, a rust-preventive primer coating is applied to the surface to form a rust-preventive primer coating, and then subjected to an organic impregnation treatment. In the method for forming a film, the rust-preventive primer contains (1) a urethane-modified epoxy resin, (2) a melamine resin, (3) a blocked isocyanate resin, and (4) a rust-free pigment containing no lead and chromium. A method for forming a rust-preventive coating film on an aluminum die-cast member surface. |