| 摘要 |
PURPOSE:To obtain a precoated metallic plate which has excellent corrosion resistance, workability and resistance to contamination, by subjecting the metallic plate to a chemical conversion with a prescribed component then using undercoating paint and top coating paint in combination. CONSTITUTION:A coating type chromate treating soln. contg. 10-200g/l (in terms of CrO3) Cr<6+>, 30-70wt% (based on the total weight of Cr) Cr<3+> and >=1 kind among silica, phosphoric acid and malonic acid is prepd. A corrosion preventive film is formed on the surface of the metallic plate with such treating soln. so as to contain 20-100mg/m<2> Cr in the dry film. Undercoating paint is coated and baked thereon to 5-20mu thickness and top coating paint is coated thereon to 5-30mu dry paint film thickness and is then baked. The above-described undercoating paint consists of 100 parts a copolymerized polyester resin of 10,000-20,000mol.wt., 5-43 parts a hardener, etc. The top coating paint consists essentially of 100 parts a copolymerized polyester of 2,000-5,000mol.wt., 0.1-3 parts a fluorine surfactant, 5-43 parts a hardener, etc. |
