To moreover improve the coating suitability of a thick film and the smoothness of a coating film by controlling the temp. of a bath for a coating material in which the content of an organic solvent is controlled to the value equal to or below a specified one to a specified range, dipping the electrically conductive material to be coated therein and executing electro-deposition coating.
The temp. of a bath for a coating material in which the content of an organic solvent is ≤0.5 wt.% is controlled to about 30 to 45°C. As a cationic electro- deposition coating material, the one consisting essentially of a water dispersed soln. or an aq. soln. oaf a resin for a cationic electro-deposition coating material and contg., at need, a crosslinkable agent, a colored pigment, a rust preventive pigment, or the like is cited. As the resin for the cationic electro-deposition coating material, an epoxy resin in which a crosslinkable functional group such as hydroxyl group and a cationic group are jointly present in the same molecule is used, and a polyamine resin obtd. by adding this resin with an amine compd. is suitable because of its good corrosion preventability. In the epoxy resin to be added with the amine, the numeric average molecular weight is desirably controlled to ≥200, particularly to 400 to 4000, and it is obtd. by the reaction of a polyphenol compd. and epichlorhydrin.
SOGA TOSHIHARU
TOMINAGA AKIRA
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