用负载型Z-N催化剂制备形貌规则的空心球形聚乙烯粒子
发布时间：2018-08-23 08:22
【摘要】：采用一种含二酯类内给电子体的氯化镁负载Ziegler-Natta催化剂和三异丁基铝(TIBA)助催化剂,在同一反应器中经常压丙烯预聚和加压下的乙烯与少量丙烯淤浆共聚合两步反应,高效地合成了外径为0.4~3 mm的中空球形聚乙烯粒子,其球形粒子的外表面和内部空腔的内表面均较为平滑,壳层厚度均匀.聚合反应的催化剂效率最高达到7.49 kg/g Ti·h·MPa(6.5 kg PE/g Cat.).研究了助催化剂种类、助催化剂浓度(Al/Ti摩尔比)和乙烯聚合阶段的丙烯共单体添加量对聚合物粒子形貌的影响,发现采用三乙基铝(TEA)或TEA/TIBA混合物为助催化剂时,虽然聚合物粒子仍呈中空球形形态,但其内部空腔的形状极不规则.以TIBA为助催化剂时,在一定范围内提高Al/Ti比和丙烯添加量均可显著提高催化效率,聚合反应动力学曲线由衰减型变为增长型,但聚合物粒子的中空形貌得以保持.对比丙烯预聚产物的粒子形貌发现,助催化剂含TEA时所得预聚物粒子结构较松散,内部有较多孔隙和裂纹,而改为TIBA后预聚物粒子内部相对致密.
[Abstract]:A magnesium chloride supported Ziegler-Natta catalyst and triisobutyl aluminum (TIBA) co-catalyst were used in the two-step copolymerization of ethylene with a small amount of propylene slurry in the same reactor. Hollow spherical polyethylene particles with an outer diameter of 0.4 ~ 3 mm were synthesized efficiently. The outer surface of the spherical particles and the inner surface of the inner cavity were smooth and the shell thickness was uniform. The catalyst efficiency of polymerization is up to 7.49 kg/g Ti h MPa (6.5 kg PE/g Cat.). The effects of the type of co-catalyst, the concentration of co-catalyst (Al/Ti molar ratio) and the amount of propylene monomer in ethylene polymerization on the morphology of polymer particles were studied. It was found that when the mixture of triethylaluminum (TEA) or TEA/TIBA was used as co-catalyst, Although the polymer particles are still hollow spherical, the shape of the inner cavity is extremely irregular. When TIBA was used as the co-catalyst, the catalytic efficiency could be significantly improved by increasing the ratio of Al/Ti and the amount of propylene in a certain range. The kinetics curve of polymerization changed from attenuated type to growth type, but the hollow morphology of polymer particles was maintained. Comparing with the morphology of propene prepolymer, it was found that the structure of the prepolymer was looser, and there were more pores and cracks in the prepolymer when the catalyst contained TEA, but the prepolymer particle was relatively dense after the change to TIBA.
【作者单位】： 浙江大学高分子科学与工程学系高分子合成与功能构造教育部重点实验室;
【基金】：国家自然科学基金(基金号21374094) 国家高技术研究发展计划(863计划,项目号2012AA040305)资助项目
【分类号】：O643.36;TQ325.12
本文编号：2198472
[Abstract]:A magnesium chloride supported Ziegler-Natta catalyst and triisobutyl aluminum (TIBA) co-catalyst were used in the two-step copolymerization of ethylene with a small amount of propylene slurry in the same reactor. Hollow spherical polyethylene particles with an outer diameter of 0.4 ~ 3 mm were synthesized efficiently. The outer surface of the spherical particles and the inner surface of the inner cavity were smooth and the shell thickness was uniform. The catalyst efficiency of polymerization is up to 7.49 kg/g Ti h MPa (6.5 kg PE/g Cat.). The effects of the type of co-catalyst, the concentration of co-catalyst (Al/Ti molar ratio) and the amount of propylene monomer in ethylene polymerization on the morphology of polymer particles were studied. It was found that when the mixture of triethylaluminum (TEA) or TEA/TIBA was used as co-catalyst, Although the polymer particles are still hollow spherical, the shape of the inner cavity is extremely irregular. When TIBA was used as the co-catalyst, the catalytic efficiency could be significantly improved by increasing the ratio of Al/Ti and the amount of propylene in a certain range. The kinetics curve of polymerization changed from attenuated type to growth type, but the hollow morphology of polymer particles was maintained. Comparing with the morphology of propene prepolymer, it was found that the structure of the prepolymer was looser, and there were more pores and cracks in the prepolymer when the catalyst contained TEA, but the prepolymer particle was relatively dense after the change to TIBA.
【作者单位】： 浙江大学高分子科学与工程学系高分子合成与功能构造教育部重点实验室;
【基金】：国家自然科学基金(基金号21374094) 国家高技术研究发展计划(863计划,项目号2012AA040305)资助项目
【分类号】：O643.36;TQ325.12
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