球型氯化镁负载型单茂钛催化乙烯与1-己烯共聚

以球型MgCl2为载体的Ziegler-Natta催化剂与含有茂配体的硅烷化合物反应,制备了一种球型MgCl2负载型单茂钛催化剂。利用该类催化剂进行了乙烯与1-己烯共聚,并考察了配体种类、聚合温度、助催化剂与球型MgCl2负载型单茂钛催化剂的摩尔比(n(Al)∶n(Ti))、1-己烯浓度等对乙烯与1-己烯共聚的影响,并用核磁共振(13C NMR)技术对乙烯与1-己烯共聚物进行表征。实验结果表明,该类催化剂表现出明显的共单体效应;茂金属配体影响催化剂活性的高低顺序为Me4Ind>Ind>Cp>Me4Cp(其中Me表示甲基、Ind表示茚基、Cp表示环戊二烯基);聚合温度50℃、n(Al)∶n(Ti)=500时,催化剂的活性较高;1-己烯的浓度对催化剂活性的影响较大。13C NMR表征结果显示,该共聚物为无规共聚物,其分布序列为单个的1-己烯镶嵌在大段的乙烯分子链中。

Application of Spherical MgCl2 Supported Mono-Titanocene Catalysts in Copolymerization of Ethylene and 1-Hexene

Novel spherical MgCl2 supported mono-titanocene catalysts were prepared by reaction of spherical MgCl2 supported Ziegler-Natta catalyst with silicane compounds.The catalysts were used in copolymerization of ethylene and 1-hexene.The obtained copolymers were characterized by means of 13C NMR.Catalysts with different ligands exhibit obvious comonomer effect in copolymerization.Effects of metallocene ligands on activity of the catalyst in copolymerization are in order as follows: Me4Ind>Ind>Cp>Me4Cp(where Me4Ind:2,3,4,7-tetramethyl indenyl;Cp: cyclopentadienyl;Me4Cp: 2,3,4,5-tetramethyl cyclopentadienyl).Under optimal copolymerization conditions: reaction temperature 50 ℃ and n(Al) ∶n(Ti) 500,copolymerization activity of catalyst is the highest.Concentration of 1-hexene is also an important factor affecting the copolymerization.13C NMR spectrum of the copolymer shows that average sequence length of 1-hexene in copolymer molecule is approximately 1 and the copolymer is atactic.