Aliphatic polyester and process for the production thereof

摘要

A process of producing a polyester or copolyester, wherein at least one cyclic lactone of the following formula (I):wherein n is an integer of 1-4 provided that n is not 2 when only one cyclic lactone is used, is polymerized under a pressure of at least 200 MPa in the absence of any catalyst or in the presence of a metal-free polyesterification catalyst.