摘要
综述了单茂金属化合物催化烯烃聚合的机理及研究进展。指出ⅣB族元素钛、锆、铪的单茂金属化合物催化烯烃及α-烯烃的均聚和共聚的活性很好,并通过改变配体结构及聚合条件可得到立构规整性的聚合物;桥联的单茂金属化合物催化乙烯、丙烯聚合的活性相当高,可得到高间规度的聚丙烯和支化的超低密度聚乙烯,但催化苯乙烯的活性很低;VB族元素钒、铌、钽的单茂金属化合物作为烯烃催化剂可得到分子量分布相当窄(1.05)的聚烯烃;另外,单茂铬化合物在很低的Al/Cr(45~100)下具有相当高的催化活性,单茂镍化合物由于其亲氧性小,可催化极性单体(如甲基丙烯酸甲酯等)聚合。
This paper reviewed the latest progresses in the studies on the mechanism of olefin polymerization and the half-metallocene catalysts thereof. The half-metallocene catalyst of the element Ti, Zr and Hf in IVB group possessed high activity in the homo- and co-polymerization of ethylene and a-olefins. The polymers with stereospecificity could be synthesized by changing the structure of ligand and the polymerization conditions. The bridged half-metallocene exhibited a pretty high catalytic activity in the polymerization of ethylene and propylene due to its structural feature; polypropylene with high syndiotacticity and branched polyethylene with ultra-low density could be prepared with the catalyst. However, the catalyst suffered a low activity in the polymerization of styrene. The half-metallocene of the elements V, Nb and Ta in VB group could be used in the polymerization of olefin to prepare polymer with rather narrow molecular weight distribution (1.05). In addition, the half-metallocene showed a high catalytic activity in case of using a very low ratio of Al to Cr (45 - 100). The half-metallocene of nickel was able to catalyze polar monomers such as methyl methacrylate due to its low oxyphility.
出处
《合成树脂及塑料》
CAS
2003年第1期67-71,共5页
China Synthetic Resin and Plastics