To furnish dust-proof property and chemical resistance even with a moist undercoat by coating with a coating compsn. comprising a hydrolyzable silyl group-contg. polymer, a curing agent or a curing catalyst, and a pigment or a solvent, to provide a coating film formed from the compsn. with a specific steam permeability and a specific pigment vol. content.
This coating compsn. contains a polymer having a hydrolyzable silyl group, a curing catalyst comprising an organotin compd. such as dibutyltin dilaurate, and an amine, a piment or an org. solvent, and, optionally, a dehydrating agent or an alkyl alcohol. A coating film formed from this coating has a steam permeability of 40-200 g/m2.24 hr, and a pigment vol. content of 5-30%. The hydrolyzable silyl group-contg. polymer is an acrylic/silicone resin represented by the formula, having a hydrolyzable silyl group, and with a wt. average mol.wt. of 10,000-60,000. The total SiO2-converted content of the silyl groups of the silyl group-contg. polymer and of the silane coupling agent is 1.0-6.0 wt.%. In the formula, R1 represents 1-10C alkyl; R2 represents hydrogen, 1-10C alkyl or the like; and a represents 0, 1, or 2.
YOSHIOKA NORIHIKO
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