| 摘要 |
PROBLEM TO BE SOLVED: To provide a coating method which is capable of eliminating environmental problems, such as waste liquid treatment, and is capable of improving the corrosion resistance of a metallic material coated with an aqueous coating. SOLUTION: The metallic material is subjected to ordinary pretreatment, such as degreasing, then to chemical conversion treatment by a phosphate chemical conversion treatment liquid of a pH 2.5 to 3.5 containing phosphate ions, chlorate ions, sulfate ions and bromate ions and zirconium hexafluoride ions of 200 to 800 ppm in content (chemical conversion treatment process step). The metallic material is then subjected to film forming treatment, etc., prior to coating and is manufactured from raw materials containing 10 to 70 mass% monofunctional monomer having 6 to 18C alkyl chains without undergoing the film forming treatment, etc. In addition, the thermosetting type aqueous coating composition containing a water-soluble polyester resin of 1,000 to 10,000 in number average molecular weight, 20 to 80 in acid value and 50 to 200 in hydroxy value and a hardener is applied on the film formed by the chemical conversion treatment (coating process step).
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