COPOLYESTER, AQUEOUS DISPERSION, AND AQUEOUS PAINT USING SAME

The present invention aims to provide a copolymerized polyester which is effective as a binder ingredient for aqueous paint, and a copolymerized polyester aqueous dispersion. In an aqueous paint composition using said copolymerized polyester resin, the present invention also aims to provide an aqueous paint, a copolymerized polyester and a resin composition which are excellent in storage stability, surface hardness, flexibility and water resistance. According to the present invention, there is provided a copolymerized polyester (A) containing a polyvalent carboxylic acid ingredient and a polyhydric alcohol ingredient as copolymerization ingredients, wherein, when a total content of the polyvalent carboxylic acid ingredient is taken as 100% by mol, a sum of a content of an aromatic polyvalent carboxylic acid ingredient and a content of an alicyclic polyvalent carboxylic acid ingredient is 100% by mol and, when a total content of the polyhydric alcohol ingredient is taken as 100% by mol, a content of a glycol ingredient (a) is 10 to 40% by mol, wherein the glycol ingredient (a) has such a structure that two hydroxyl groups are bonded by an alkylene group having a number of carbon atoms of 5 or less, wherein the alkylene group has, as a side chain thereof, an alkyl group having a number of carbon atoms of 2 or more, and wherein the copolymerized polyester has a glass transition temperature of -10 to 20°C and an acid value of 150 to 400 equivalents/ton.