| abstract |
Provided are an aliphatic polyester resin having a high molecular weight and, in the preferred state, a high melting point and excellent thermal stability and hue, and an effective method for the production of same. The method for producing the aliphatic polyester includes a melt polymerization process and a subsequent solid phase polymerization process, with a sulfonic-acid-group-containing compound as catalyst, and the amount of sulfonic-acid-group-containing compound added during the melt polymerization process, calculated as sulfur atoms, is from 300 to 3,000 ppm with respect to the raw material monomer, the sulfonic-acid-group-containing compound content after the solid phase polymerization, calculated as sulfur atoms, is from 300 to 3,000 ppm with respect to the product polymer, and more than 50% of the sulfonic-acid-group-containing compound remains after the solid phase polymerization. The aliphatic polyester resin composition contains in the aliphatic polyester resin an amount, calculated as sulfur atoms, of from 300 to 3,000 ppm with respect to the product polymer of a sulfonic-acid-group-containing compound having two or more sulfonic acid groups in one molecule. |