Method of multistage solid-phase polycondensation of polyethylene terephthalate

摘要

A method of producing a polyethylene terephthalate, comprising performing a heat treatment of a polyethylene terephthalate prepolymer having an intrinsic viscosity of 0.18 dL/g or more and 0.40 dL/g or less in a solid state to provide an intrinsic viscosity of 0.70 dL/g or more,
wherein the heat treatment in the solid state comprises a first-stage solid-phase polycondensation step, a temperature increase step, and a second-stage solid-phase polycondensation step in the stated order