茂金属催化剂负载对丙烯间规聚合的影响

茂金属催化剂具有活性高、定向性好的特点 .采用茂金属催化剂 ,Ｅｗｅｎ1] 首次在常温、常压下实现了丙烯的间规聚合 ,得到了高间规度 (ｒｒｒｒ >80 % )的间规聚丙烯 (ｓＰＰ) .ｓＰＰ因其透明性好、耐冲击及耐辐射 ,室温韧性、热密封性及透气性好等特性 ,作为共混材料 ,在医疗产品、包装、纤维、薄膜和汽车配件等方面显示了广阔的应用前景 .国内外许多公司都投入大量人力、物力进行研究 .其中 ,Ｆｉｎａ公司处于技术领先地位 .Ｆｉｎａ公司继 1 987年开发出间规选择性茂金属催化剂后 ,成功地进行了中试聚合实验 ,得到了商用ｓＰＰ .1 994…

THE STUDY OF SYNDIOSPECIFIC POLYMERIZATION OF PROPYLENE WITH SUPPORTED METALLOCENE CATALYST

The syndiotactic polypropylene ( s PP) with high bulk density and sphere like was prepared in bulk process by syndiospecific metallocene catalyst,which was synthesized and supported on silica by ourself.To avoid the active center of the metallocene catalyst leaching from silica surface that would foul reactor in polymerization,the blend of methylaluminoxane (MAO) and metallocene catalyst was deposited on silica treated by MAO first,then washing three times at least by hexane.The polymerization was carried out in 5 L reactor.The results verified that the high polymerization activity and syndiospecification of the metallocene catalyst were preserved after being supported.The polymerization activity and the pentad concentration of s PP are more than 10 6 g s PP/molZr\5h and 75%,respectively.The morphology and distribution of s PP particles were modified remarkably.Through studying the polymerization process,the effects of the polymerization temperature and the catalyst concentration on the polymerization results were inspected including polymerization activity,polymer morphology and the bulk density of polymer.When polymerization activity is in the range of 3～4×10 6g s PP/molZr\5h,the sphere like s PP with weight average molecular weight ( M w) between 15～45×10 4 and the bulk density between 0 35～0 45?g/cm 3 was obtained.