Polyethylene terephthalate for molding and production the same

Details Polyethylene terephthalate for molding and production the same Polyethylene terephthalate for molding and production the same

2007-06-26

2007-06-26

Boykin, Terressa (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From carboxylic acid or derivative thereof

C525S437000, C528S271000, C528S308600, C528S50200C, C528S503000

Reexamination Certificate

active

10550916

ABSTRACT:
There is provided a method for producing a polyethylene terephthalate for molding which has a low content of cyclic trimer. The present invention is a method for producing a polyethylene terephthalate for molding which comprises (1) a condensation step of condensing bis(2-hydroxyethyl)terephthalate having an ion content of 10 ppm or less and an acid value of 30 mgKOH/g or less to produce an oligomer having an average polymerization degree of 4 to 10, (2) a melt-polymerization step of melt-polymerizing the oligomer to produce a prepolymer having an intrinsic viscosity of 0.50 to 0.65, and (3) a solid-state polymerization step of crystallizing pellets of the prepolymer and then solid-state polymerizing the prepolymer at a temperature of 190 to 230° C. to produce a polyethylene terephthalate having an intrinsic viscosity of not lower than 0.65; and a polyethylene terephthalate for molding which is obtained by the method and has specific properties.

REFERENCES:
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