| 摘要 |
PROBLEM TO BE SOLVED: To reduce the base treatment process for a surface to be coated, to prevent rusting and to keep the adhesive property of a rust preventive coating material over a long period by forming a chemical coating film on the surface to be coated and after that, applying an alkali group containing coating material. SOLUTION: A chemical coating film is formed by applying a chemical coating film forming agent prepared by blending a fluorine compound, an oxalate and the like in a tannic acid aq. solution on a steel structure base-treated with sand blast or the like and drying. As the alkaline coating material applied on the chemical coating film, a rust preventive coating composition prepared by blending 10-300 pts.wt. slag containing 30-70% CaO with 100 pts.wt. resin solid matter composed of an epoxide resin having an average molecular weight of 300-300 and an epoxide equivalent of 180-2200 and a hardening agent is used. As the alkali group-containing slag, blast furnace granulate slag having 0.1-100μm particle diameter or the like is used. The surface of the chemical coating film is previously neutralized or alkalified by applying a liquid prepared by eluting a slag component before the coating material is applied and in such a case, it is unnecessary to use the alkaline coating material.
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