| 摘要 |
PROBLEM TO BE SOLVED: To obtain a polyester useful as a material for a hollow molding product such as a bottle for drinking, etc., for a molding product such as a sheetlike material, an oriented film, etc., by making the rate of change of dimension of a molding product prepared by melt molding of polyester in a specific range. SOLUTION: This polyester is obtained by making the rate of change of dimension (by thermomechanical analysis) of a molding product prepared by the melt molding of a polyester comprising ethylene terephthalate as a main repeating unit <=4.0%. Preferably the polyester has 0.55-0.90 deciliter/g intrinsic viscosity, 1.0-5.0 mol% based on a glycol component of content of diethylene glycol copolymerized with the polyester, >=1.37 g/cm3 density, <=10 ppm acetaldehyde content and <=0.5 wt.% cyclic trimer content. The polyester can be produced by adding 0.1-1,000 ppm of a polyacetal to a polyester.
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