Patent ID: 8658758

Claim:
A process for producing an aliphatic polyester with a reduced content of residual cyclic ester, comprising: producing an aliphatic polyester by ring-opening polymerization of a cyclic ester comprising glycolide or a mixture of glycolide and lactide containing 70 wt. % or more of the glycolide, wherein the polymerization proceeds in the presence of a metallic catalyst selected from the group consisting of oxides, chlorides, carboxylates and alkoxides of tin (Sn), titanium (Ti), aluminum (Al), antimony (Sb), zirconium (Zr) and zinc (Zn), and a latter period of the polymerization proceeds by solid-phase polymerization, pelletizing the aliphatic polyester after the polymerization together with a thermal stabilizer, and then contacting the pelletized aliphatic polyester containing the thermal stabilizer with a flowing heated dry gas at 150-220° C. for 2-24 hours under normal pressure while retaining the pelletized aliphatic polyester in its solid state, thereby entraining residual cyclic ester with the gas and reducing the content of residual cyclic ester in the aliphatic polyester down to 0.02-0.13 wt. % below 0.2 wt. %.