A PROCESS FOR THE POLYMERIZATION OF POLYESTER RESINS IN THE SOLID STATE, IN PARTICULAR OF POLYETHYLENE TEREPHTHALATE, AND APPARATUS OPERATING IN ACCORDANCE WITH THE PROCESS

摘要

A process for the polymerization of polyester resins in the solid state comprises the step of exposing the resin to a gas-flow for a predefined period of time and at a predefined temperature in order to increase the degree of polymerization of the resin. The gas used has an oxygen fraction of between 0.1% and a maximum permissible oxygen fraction which is determined in dependence on the moisture content of the gas.