Impact modifier and polyester composition containing the modifier

摘要

A lactic acid polyester (III), having a lactic acid unit (I) and a polyester unit (II) at a weight ratio within the range of 10:90 to 90:10, a weight average molecular weight of 10,000 or more, and a glass transition temperature of 60° C. or below, imparts superior impact resistance to polyhydroxy carboxylic acids while maintaining superior flexibility and transparency and with minimal occurrence of bleedout.