| 摘要 |
PROBLEM TO BE SOLVED: To provide a self-precipitation type coating composition which can achieve equivalent coat precipitation properties and film quality for multi-metal materials through the same self-precipitation type coating composition and a resin coating method using the composition.SOLUTION: A method of producing a self-precipitation type coating composition for multi-metal materials includes a step of adding a water-dispersible or water-soluble anionic organic resin, a soluble trivalent iron source, a soluble fluorine source and an organic ingredient having at least one carboxyl group or salt thereof in a molecule, to a water-based solvent. In the step, the molar ratio of the soluble fluorine to the soluble trivalent iron dissolved in the water-based solvent, ([mol number of soluble fluorine])/([mol number of soluble trivalent iron]) and, in cases where the organic ingredient is an organic acid metal salt, ([mol number of soluble fluorine])/([mol number of soluble trivalent iron]+[mol number of metal cation ingredient originated from the organic acid metal salt]), is 1.0-3.2. |
