Patent ID: 7153587

Claim:
A polyester resin (A) comprising (a-1) 45 to 99% by mole of an oxycarboxylic acid unit having 5 carbon atoms or less, (a-2) 0.5 to 27.5% by mole of an aromatic dicarboxylic acid unit, (a-3) 0.5 to 27.5% by mole of an aliphatic diol unit having 4 carbon atoms or less, based on 100% by mole of the total constituent units, and containing the oxycarboxylic acid unit having 5 carbon atoms or less (a-1), the aromatic dicarboxylic acid unit (a-2) and the aliphatic diol unit having 4 carbon atoms or less (a-3) in a total amount of 95% by mole or greater, wherein the relationship between the content of the oxycarboxylic acid unit, expressed as M % by mole, and the density of the polyester resin, expressed as ρ (kg/m 3 ), satisfies the following Formula 1: ρ≧1349 +M ×0.85. [Formula 1]