| 摘要 |
PURPOSE:To eliminate the peeling of a coating film and the lowering of corrosion resistance of the obtained titled steel plate during processing, by a method wherein coating type chromate with excellent close adhesiveness is applied to a cold rolled steel plate or a zinc plated steel plate to form a primer coating and a specific zinc rich coating film is formed on said primer coating. CONSTITUTION:A solution type composition consisting of chromic anhydride, an org. reducing agent, water soluble acrylic resin and water or an emulsion type composition consisting chromic anhydride, an org. reducing agent, water dispersible acrylic resin and water is applied to a cold rolled steel plate or a zinc plated steel plate as primer coating. In this case, said composition is coated in an amount of 50-500mg/m<2> as a total chromium amount and dried. In the next step, a top coat composition containing telephthalic acid in an amount of 30-70mol% on the basis of a total org. polyester resin with average number M.W. of 2,000-30,000, melamine resin or blocked isocyanate as a curing agent, a zinc powder and a solvent is applied to the formed primer layer. In this case, the top coat composition is coated in a dry film thickness of 3-20mum and baked and dried. |
