粉末PET固相缩聚的研究

Study on solid-state polycondensation of PET particles

系统地研究了粉末聚酯(PET)固相缩聚,得到了有效的干燥结晶条件:140℃干燥120 min,180℃再结晶45 min,切片含水率低于30μg／g;研究了反应温度,粉末粒径和N2流量对PET固相缩聚的影响,分析粉末固相缩聚存在N2流量阈值的机理。结果表明:反应温度越高,颗粒越小,固相缩聚反应速度越快;粉末 PET预聚体在一定温度下固相缩聚,存在N2流量阈值。在此流量下,达到该温度下的该粒径粉末的最大界面扩散速率和固相缩聚的最大反应速度。相同反应温度下,粉末粒径越小,阈值N2流量越大。

The solid-state polycondensation of PET particles was studied systematically. The drying and crystallization conditions were optimized as drying temperature 140℃ and time 120 min, crystallization temperature 180℃ and time 45 min, chips water content lower than 30μg/g. The effects of reaction temperature, particle size and N2 flow rate on the solid-state polycondensation of PET were studied. The mechanism of the threshold N2 flow rate was analyzed during the process of solid-state polycondensation. The results showed that the higher the reaction temperature, the smaller the particle, the faster the solid-state polycondensation. The PET prepolymer particles were supposed to solid-state polycondensation at a certain temperature, during which the threshold N2 flow rate can be observed. The interface diffusion rate of PET particles and the reaction rate of the solid-state polycondensation can be maximized under the threshold N2 flow rate at the specified temperature. The smaller the particles, the higher the threshold N2 flow rate.