新型聚酯液相增黏工艺技术浅析

Analysis of a novel liquid-state polycondensation technology for polyester

介绍了一种新型聚酯液相增黏工艺技术及其应用。新型液相增黏工艺技术的核心是在传统聚酯装置上重新设计后缩聚反应器、真空系统和熔体输送系统。后缩聚反应器使用三段式气相空间结构的卧式圆盘反应器,成膜性能好、界面更新速率快、小分子脱挥空间大,能有效防止熔体的滞留;真空系统使用四级乙二醇喷射泵和干式螺杆真空泵,并采用较低的乙二醇喷淋温度(35~40℃)和合适的液气比(1 500~2 000),使聚合体系压力达到50 kPa以下;熔体输送系统中控制熔体输送温度(287~296℃)和流速(0.1~0.2 m/s),防止高黏熔体在输送过程中降解。与传统液相增黏工艺相比,新型液相增黏工艺不需要新增加液相增黏反应器、脱醛设备及真空系统。在100 kt/a聚酯装置上,传统聚酯工艺生产的产品特性黏数为0.636 dL/g,而应用新型液相增黏工艺可获得特性黏数为0.805 dL/g的高黏度聚酯产品。

A novel liquid-state polycondensation technology for polyester and its application were introduced. The key of the novel liquid-state polycondensation technology is to redesign the post-polycondensation reactor, vacuum system and melt conveying system based on the traditional polyester plant. The post-polycondensation reactor uses a horizontal disk reactor with three-stage gas-phase space structure, which can effectively prevent the melt retention due to its good film-forming performance, high surface renewal rate and large devolatilization space of small molecules. The vacuum system uses four-stage ethylene glycol jet pump and dry screw vacuum pump and adopts relatively low ethylene glycol spray temperature(35-40 ℃) and appropriate liquid-gas ratio(1 500-2 000) to ensure the polymerization system pressure below 50 kPa. The melt conveying temperature and flow rate should be controlled as 287-296 ℃ and 0.1-0.2 m/s, respectively, in the melt conveying system to prevent the degradation of high-viscosity melt during the conveying process. Compared with the traditional liquid-state polycondensation process, the novel liquid-state polycondensation process does not need an additional liquid-state polycondensation reactor, dealdehyde equipment and vacuum system. On a 100 kt/a polyester plant, the product produced by the traditional polyester process has an intrinsic viscosity of 0.636 dL/g, while the high-viscosity polyester product can be obtained with an intrinsic viscosity of 0.805 dL/g by using the novel liquid-state polycondensation process.