POLYETHYLENE TEREPHTHALATE FOR MOLDING AND PROCESS FOR PRODUCING THE SAME

摘要

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.