Rust preventive coating and method for forming the same

Abstract

(1) An undercoat layer is formed on a surface of a substrate mainly composed of iron by coating the substrate with at least one metal selected from the group consisting of zinc, tin, lead, aluminum, chromium, nickel and copper by hot dipping, electroplating, penetration plating, thermal spraying or chemical plating, or a paint containing at least one rust preventive pigment selected from the group consisting of zinc dust, zinc chromate, minium, basic lead chromate, strontium chromate and lead chromate, and then, (2) the undercoat layer is coated with a paint composition mainly composed of (a) 100 parts by weight of an inorganic filler, (b) 5 to 30 parts by weight of a binder in terms of solid content, and (c) 10 to 100 parts by weight of water and/or a hydrophilic organic solvent, and the composition is hardened by drying at ordinary temperature or heat drying at low temperature to form an overcoat layer, thereby obtaining a rust preventive coating good in hydrophilic properties, air permeability and drying properties, and excellent in corrosion resistance.

Dependencies are inferred from the claim text.