| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polymerization catalyst for polyesters excellent in moldability and processability, in which problems such as stain of spinneret, increase of filtering pressure and yarn breakage are solved in production of a molding product for fibers, films and bottles, and provide a method for producing a polyester using the catalyst. SOLUTION: A main metal element as a polycondensation catalyst is a binuelear oxide composed of aluminum and silicon and the molar ratio of Al:Si of the composition is (90:10) to (10:90), in a method for producing a polyester by polycondensing a product obtained by esterification or transesterification of an aromatic dicarboxylic acid or its ester-forming derivative with a diol or its ester-forming derivative.
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