| 摘要 |
PROBLEM TO BE SOLVED: To obtain a coating material which, in spite of containing no lead compound, can form a coating film excellent in low-temperature curability, anticorrosiveness, solvent resistance, mechanical properties, etc., by using a basic zinc silicate having a specified composition. SOLUTION: The basic zinc silicate is one having a zinc/silicon ratio of 1.1/1 to 2.5/1 by mole and is exemplified by Zn(OH)2.ZnSiO3 (the so-called basic zinc metasilicate). The basic zinc silicate is desirably one that has a zinc elution level of at least 1,000 ppm as measured according to the boiling elution method described in JIS K-5101, 25 in an acidic aqueous solution at a pH of 3 or below and a zinc elution level of at most 100 ppm in an aqueous solution at a pH of 5 or above. It is desirable that the amount of the basic zinc silicate used is 0.5-5 pts.wt. per 100 pts.wt. resin solid content. It is desirable in order to improve the anticorrosiveness that the coating material contains in addition to the basic zinc silicate at least one member selected from bismuth-containing compound and a zirconium-containing compound.
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