| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a waterborne middle coating material composition excellent in coating workability (in particular sag resistance) for obtaining a coated film giving flat and superior appearance. <P>SOLUTION: This waterborne middle coating material composition includes (A) a water-soluble or water-dispersible polyester resin, (B) a melamine resin and (C) polypropylene glycol as essential components. The component (A) is a polyester resin obtained by adding glycol monoalkylether (a) containing a 1C-3C alkoxy group to a polyester resin with a resin acid number of 25-35 mgKOH/g, in an amount of 7-20 mass% to the mass of resin solid content of the component (A), and further neutralizing with a secondary amine and/or tertiary amine to be aqueous. The component (B) is a methylated melamine resin and a methyl/butyl mixed-alkylated melamine resin. The solid content mass ratio of the methylated melamine resin to the methyl/butyl-mixed alkylated melamine resin is 50/50 to 90/10. The content mass ratio of resin solid content of the component (A) to that of the component (B) is 70/30 to 90/10; the number-average molecular weight of the component (C) is 400-1,200; and the content mass ratio of the component (C) is 1-10 mass% to the total mass of resin solid content of the component (A) and the component (B). <P>COPYRIGHT: (C)2013,JPO&INPIT |
