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AssigneeToyo Seikan Kaisha, Ltd.
InventorsKazuhiko NAKAMURA, Yoshihiro KITANO, Atsushi KIKUCHI
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Ethylene terephthalate polyester resin for forming containers, having intrinsic viscosity of 0.65 to 0.85 dL/g, a 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 an 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 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 problems metal mold fouling in forming containers or a decrease in productivity.
An ethylene terephthalate type polyester resin for forming heat-resistant containers, having an intrinsic viscosity in a range of 0.65 to 0.80 dL/g, a total content of a monohydroxyethyl terephthalate and a bishydroxyethyl terephthalate of less than 0.005% by weight, an acetaldehyde concentration of 2 to 10 ppm, and satisfying at least either one of:
A process for producing an ethylene terephthalate type polyester resin by heat-treating an ethylene terephthalate type polyester resin, which is obtained by the melt state polymerization, at a temperature of 160 to 220° C. for not less than 1 hour but less than 5 hours.
Dependencies are inferred from the claim text.