METHOD FOR PRODUCING ALIPHATIC POLYESTER RESIN, AND AN ALIPHATIC POLYESTER RESIN COMPOSITION

摘要

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 a method for effectively producing the same are provided. A method for producing an aliphatic polyester resin including a melt polymerization step and a subsequent solid phase polymerization step, using a sulfonic acid group-containing compound as a catalyst, wherein the addition amount of the sulfonic acid group-containing compound during melt polymerization is 300 to 3000 ppm with respect to a raw material monomer calculated as sulfer atoms, the content of the sulfonic acid group-containing compound during melt polymerization is 300 to 3000 ppm with respect to a produced polymer calculated as sulfer atoms, and a residual rate of the sulfonic acid group-containing compound after solid phase at polymerization is more than 50%. Further, an aliphatic polyester resin composition containing a sulfonic acid group-containing compound having 2 or more sulfonic acid groups in one molecule in an aliphatic polyester resin, in a content of 300 to 3000 ppm with respect to a produced polymer calculated as sulfur atoms.