AQUEOUS MID-COAT PAINT COMPOSITION

摘要

To provide an aqueous mid-coat paint composition with which paint films which have excellent painting operability (and especially sag resistance) and which are smooth and of good appearance can be formed. [Means of Resolution] An aqueous mid-coat paint composition which is characterized in that it contains (A) water-soluble or water- dispersible polyester resin, this being a polyester resin where, within the resin, there are included from 2 to 10 mass% of linear chain or branched chain polyethylene glycol groups or polyethylene glycol ether groups of number average molecular weight from 300 to 600, and in which there are also included carboxylic acid secondary or tertiary amine salt groups which have been obtained by neutralizing at least some of the carboxylic acid groups in the resin, and in which there are a total number of from 0.8 to 1.2 of said polyethylene glycol groups or polyethylene glycol ether groups and said carboxylic acid secondary or tertiary amine salt groups per number average molecular weight of the resin, and where the acid value of the polyester resin before said carboxylic acid groups are neutralized with said secondary or tertiary amine is not more than 30 mgKOH/g, the hydroxyl group value is from 90 to 160 mgKOH/g and the number average molecular weight is from 1,300 to 1,900, and (B) melamine resin as curing agent, and the ratio by mass of the resin solid fractions of the (A) component and the (B) component is from 75/25 to 90/10.