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Abstract

An ethylene terephthalate type polyester resin for forming containers, having an intrinsic viscosity in a range of 0.65 to 0.85 dL/g, a total content of a monohydroxyethyl terephthalate and a bishydroxyethyl terephthalate of less than 0.005% by weight, (a) a heat of fusion of not more than 50 J/g, a end temperature of melting peak of not higher than 270° C. and a crystallinity of less than 0.48, or (b) an acetaldehyde concentration of 2 to 10 ppm, and satisfying at least either one of (i) a peak time of crystallization is not longer than 360 seconds and the crystallization energy (ΔH) is not less than 30 J/g in the isothermal crystallization at 210° C., or (ii) components having molecular weights of not larger than 10000 are contained in not less than 8%. The polyester resin effectively prevents the problems such as a fouling of the metal mold in forming containers or a decrease in the productivity. A decreased acetaldehyde concentration provides excellent flavor-retaining property. Further, the heat-setting and mouth portion crystallization can be efficiently conducted making it possible to produce heat-resistant containers maintaining good productivity.

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