| 摘要 |
PROBLEM TO BE SOLVED: To improve press workability and corrosion resistance of worked part by forming a dry coating film of an organic resin in a specified thickness on one side of an Al-based-plating processed steel plate with a specific treatment liquid in which silica sol of a specified amount and a chromate of a specified amount are added. SOLUTION: Urethane-resin film is applied on at least one side of an Al- based-plating processed steel plate by a known application method such as a roll-coating method, by using a dispersion of an aqueous urethane resin in which silica sol and a chromate are added, in this case, amount of silica sol/(aqueous urethane resin non-volatilable content + amount of silica sol) = 0.10-0.14, and amount of chromate/(aqueous urethane resin non-volatilable content + amount of silica sol) = 0.001-0.10, and the film thickness is set to be 0.5-2.0μm.
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