| 摘要 |
PROBLEM TO BE SOLVED: To provide a preparation process of a polyester which easily yields a polymer having a high degree of polymerization with a little amount of catalyst without employing any high-boiling solvents or dehydration operations such as depressurization, etc. SOLUTION: In the presence of a distannoxane catalyst of the formula (wherein R1, R2, R3 and R4 are identical to or different from each other and are each an alkyl group; and X and Y are identical to or different from each other and are each an isothiocyanate group, halogen atom, hydroxy group, alkoxy group or acyloxy group), a diol is polycondensed with a dicarboxylic acid to obtain a corresponding polyester. Here, the amount of diol used is about from 1.0 to 1.20 mol against 1 mol dicarboxylic acid. The polymer generated through polymerization is isolated through precipitation or re-precipitation in an alcohol such as methanol.
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