[C:1]([OH:6])(=[O:5])[CH:2]([CH3:4])[OH:3].[C:7]([OH:11])(=[O:10])[CH2:8][OH:9]>>[C:1]([OH:6])(=[O:5])[CH:2]([CH3:4])[OH:3].[C:7]([OH:11])(=[O:10])[CH2:8][OH:9]To 160 g (1.5 mol) of 85% lactic acid aqueous solution was added 38 g (0.5 mol) of glycolic acid and the mixture was subjected to heating under reduced pressure in nitrogen gas stream at 100° to 150° C./350 to 30 mmHg stepwise for 6 hours with removing distilled water, and then the resultant was subjected to a condensation reaction at 175° C./6 to 5 mmHg for 36 hours to give lactic acid-glycolic acid copolymer [monomer ratio: 75/25 (on a weight basis), average molecular weight: 14000, glass transition temperature: about 40 to 45° C⟧
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