| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to keep the suitability for electrostatic coating and the staining resistance of a coating film by adjusting to a specified or lower value the humidity in a tank for circulating a topcoating material prepared by mixing a thermosetting organic resin with a partial hydrolytic condensate of an organosilicate cornpound in a process for electrostatic coating with the topcoating material. SOLUTION: A topcoating material is prepared by mixing 100 pts.wt. (in terms of the solid content) thermosetting coating composition with 1-70 pts.wt. (in terms of the solid content) partial hydrolytic condensate of an organosilicate compound represented by the formula: (R1O)4-a-Si-R2a (e.g. tetraalkyl silicate). Electrostatic coating with this topcoating material is performed while the overhead space of a circulation tank for circulating the material is adjusted at a humidity of 5,000 g/m3 or below. The thermosetting organic resin is desirably a mixture being one of 90-40 wt.% hydroxyl-containing acrylic resin and 10-60 wt.% amino resin and having a number-average molecular weight of 1,000-500,000. In the formula, R1 is hydrogen, a 1-10C alkyl, or the like; R2 is a 6-10C aryl, or the like; and (a) is 0 or 1.
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