| 摘要 |
PROBLEM TO BE SOLVED: To obtain a coating composition that can be uniformly dispersed in an electrodeposition coating bath and can give an electrodeposition coating film excellent in finish and corrosion resistance without using a lead compound or the like by adding an aqueous solution of a copper aliphatic hydroxycarboxylate to an electrodeposition coating material. SOLUTION: The aliphatic hydroxycarboxylic acids useful in the production of the aqueous solution of the copper aliphatic hydroxycarboxylate are monocarboxylic acids, among which lactic acid, dimethylolpropionic acid, and dimethylolbutyric acid are desirable. The copper compound used in the production of the aqueous solution of the copper aliphatic hydroxycarboxylate is desirably a copper hydroxide. The aqueous copper hydroxycarboxylate solution is obtained by reacting 1 mol of copper hydroxide with 1.2-2.7 mol of a hydroxycarboxylic acid. The amount of the aqueous copper hydroxycarboxylate solution added may widely vary according to the requirements for an electrodeposition coating material and usually corresponds to a copper content of 0.01-10 pts.wt. per 100 pts.wt. resin solids of the electrodeposition coating material.
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