Patent ID: 7645852

Claim:
An aliphatic polyester copolymer comprising an aliphatic polycarbonate unit (a) represented by the general formula (1): wherein X 1 and X 2 are O, N—R7 or S, and may be the same or different, R1 and R2 are an alkylene chain having from 1 to 10 carbon atoms, and may be linear or branched, and R3 to R7 are a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, a cycloalkyl group or a phenyl group, wherein the alkyl group may be linear or branched, and the cycloalkyl group and phenyl group may have a substituent, and an aliphatic polyester unit (b), wherein the aliphatic polyester unit (b) is a structure derived from lactic acid.