Method for the production of hot-formed and essentially single-material recyclable plastic parts made from germ-forming-free, amorphous polyethylene terephthalate

Abstract

A process for producing hot-formed and essentially single-material recyclable plastic parts from germ-forming-free amorphous polyethylene terephthalate is described. According to the invention, in a feeding step, a semi-finished product is fed to a processing section of a production plant and heated in at least one preheating step to a drawing temperature of 80–100°C. In at least one drawing step, it is actively drawn exclusively in the machine direction to a degree of drawing of 1.2–12.0. Following the at least one drawing step, a relaxation step is performed, in which the semi-finished product undergoes a relaxation of at most 20% in the machine direction. Simultaneously with or immediately following the relaxation step, at least one post-heating step is performed, in which the semi-finished product is heated to a temperature in the range of 120–235°C.wherein the temperature of successive post-heating steps increases stepwise and wherein a forming step takes place after at least one post-heating step, wherein semi-finished products are formed and thereby quenched to a temperature of at least 30 °C below the glass transition temperature of the polyethylene terephthalate used.