| 摘要 |
<p>The invention concerns a new procedure for the manufacture of poly-(ethylene terephthalate) (PET) by raising the molecular in the liquid phase to 68,000 to 86,000 g/mol, during the step of liquid phase polycondensation and subsequently pelletizing the amorphous product, followed by a crystallization over a period of 15-60 min, at temperatures of 160-185 °C, in air, whereby the pellet temperature reach 25-180 °C. In a subsequent procedural step the pellets remain for 2-10 h at temperatures of 120 °C to 220 °C ('preheater') in an air stream, followed by treating the polyester resin thus obtained with polyols or other blocking agents at concentrations of 100 and 10,000 ppm, relative to the polyester resin.</p> |
