| abstract |
(57) [Abstract] [Problem] There are few environmental problems such as waste liquid treatment. Provided is a coating method capable of improving the corrosion resistance of a metal material coated with a water-based paint. SOLUTION: After performing a normal pretreatment such as degreasing, pH 2.5 to 3.0 containing phosphate ion, chlorate ion, nitrate ion, bromate ion and zirconium hexafluoride ion having a content of 200 to 800 ppm. The metal material is subjected to a chemical conversion treatment with the phosphate chemical conversion treatment liquid of No. 5 (chemical conversion treatment step). Then It is produced from a raw material containing 10 to 70% by mass of a monofunctional monomer having an alkyl chain having 6 to 18 carbon atoms without performing a film forming treatment or the like before coating, or without performing a film forming treatment or the like. And the number average molecular weight is 10 A thermosetting aqueous coating composition containing a water-soluble polyester resin having a value of 00 to 10,000, an acid value of 20 to 80, and a hydroxyl value of 50 to 200 and a curing agent is applied on the film formed by the chemical conversion treatment ( Painting process). |