Rust preventive composition and method of preventing zinc or zinc alloys from rusting

摘要

A rust preventive composition is provided. The composition includes an epoxy resin, a hardener, an aromatic amine-based condensation product, and a compound selected from the group consisting of a silicic acid compound and a polyvinyl butyral resin. The composition is used to form a coating film on a metallic base which liable to rust, preferably on a coating film of phosphate which is previously formed on the base. The composition imparts a good corrosion resistance comparable to chromate treatment to metals, especially Zn and Zn-alloys, but is free from any sanitary anxiety such as carcinogenesis. The surface of metal treated therewith is black. Therefore, the composition is suited for primary rust-preventive treatment.