| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject polymer having excellent heat resistance, decomposability and toughness by performing a reaction in a reaction system containing a specific hydroxycarboxylic acid and/or lactones, a polyfunctional carboxylic acid compound and/or its acid anhydride, a polyhydric alcohol and a catalyst. SOLUTION: This polymer is obtained by performing a polymerization in a reaction system containing (A) a cyclic dimer of a hydroxycarboxylic acid and/or lactones (preferably L-lactide), (B) a polyfunctional carboxylic acid compound having more than three carboxyl groups and/or its acid anhydride (e.g. 1,2,3,4-cyclopentanetetracarboxylic acid), (C) a polyhydric alcohol having more than two hydroxyl groups (e.g. ethylene glycol) and (D) a metal of I to V group in the periodic table, its oxide or its salt, etc., (e.g. zinc dust) as a catalyst. Preferably, the component B is 0.01-0.5 wt.% based on the polymer and an equivalent ratio of carboxyl group in the component B to hydroxyl group in the component C is (100/90)-(100/110). |
