Process for the preparation of high molecular lactic copolymer polyester

Abstract

A novel process for the preparation of a high molecular lactic copolymer polyester is provided, which includes allowing a lactide (A), a polyester terminated by hydroxyl group at both ends (B1), a polyvalent carboxylic acid having 3 or more functionalities and/or acid anhydride thereof (C) to undergo ring opening copolymerization in the presence of a ring opening polymerization catalyst (D). A novel process is also provided which includes allowing the lactide (A) and the polyester (B1) to undergo ring opening copolymerization in the presence of the catalyst (D) to prepare a polyester, and then reacting the polyester with the component (C). A novel process is further provided which includes reacting the polyester (B1) with the polyvalent carboxylic acid component (C) to obtain a polyester terminated by hydroxyl group at both ends having a weight-average molecular weight of from 10,000 to 300,000 (B2), and then allowing the polyester (B2) and the lactide (A) to undergo ring opening copolymerization in the presence of the catalyst (D). Another novel process is provided which includes allowing a dicarboxylic acid, a diol and the polyvalent carboxylic acid component (C) to undergo dehydration reaction and/or deglycolation reaction to obtain a polyester having a weight-average molecular weight of from 10,000 to 300,000 (B3), and then allowing the polyester (B3) and the lactide (A) to undergo ring opening copolymerization in the presence of the catalyst (D).