| 摘要 |
PROBLEM TO BE SOLVED: To provide a coated object having excellent weatherability, whiteness, adhesion and die mark hiding properties with respect to aluminum or an aluminum alloy. SOLUTION: The multilayer film forming method comprises: a stage where aluminum or an aluminum alloy is subjected to anode oxidation treatment; a stage where the aluminum or an aluminum alloy is dipped into a sulfuric acid aqueous solution or a phosphoric acid aqueous solution, and is thereafter water-washed; a stage where the aluminum or aluminum alloy is electrodeposition-coated with an anionic electrodeposition coating material containing a carboxyl group-containing resin, a cross-linking agent and pigment; and a stage where the aluminum or aluminum alloy is heated and dried, so as to form a hardened film thereon. The concentration of the pigment in the anionic electrodeposition coating material lies in the range of 6 to 18 mass% of the resin solid content, also, the pigment in the anionic electrodeposition coating material is obtained, to the total mass of (a) pigment-dispersed paste in which pigment with the average particle diameter in the range of 1 to 3μm is dispersed and (b) pigment-dispersed paste in which pigment with the average particle diameter in the range of >3 to 10μm is dispersed, by mixing the (a) in the ratio of 5 to 50 mass%, and lightness (L* value) based on an L*a*b* color system prescribed by JIS Z 8729 in the formed multilayer film lies in the range of 85 to 95. COPYRIGHT: (C)2007,JPO&INPIT
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