| 摘要 |
PROBLEM TO BE SOLVED: To provide a heavy corrosion protection coated-steel high in reliability by providing substrate treatment excellent in cathode peeling resistance required in a high temperature region. SOLUTION: As chromate treatment as substrate treatment for heavy corrosion protection coating, electrolytic chromate treatment 2 and dry silica- containing coating chromate treatment 3 are applied. After that, a resin primer layer 4, a modified polyolefin resin 5 and a polyolefin resin layer 6 are successively laminated and applied thereon. The electrolytic chromate treatment supplements the defects of steel adhesion and the coating ratio in the film crcked part in the coating chromate treatment, so that, in the case cathode corrosion protection is performed to heavy corrosion protection-coated steel, its cathode peeling resistance at high temperature can be suppressed. In this way, corrosion protection coating high in reliability can be obtained.
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