双功能催化剂体系作用下乙烯二聚和共聚合的研究

用乙烯为原料在双功能催化剂体系的作用下通过二聚和共聚合反应，直接合成线性低密度聚乙烯（ＬＬＤＰＥ）．所用二聚反应催化剂为钛酸正丁酯（Ｔｉ（ＯＢｕ）_４），共聚催化剂为ＴｉＣｌ_４／ＭｇＣｌ_２（ＺＭ－１催化剂）．研究了二聚反应动力学行为及影响双功能催化剂体系动力学过程的一些因素．结果表明利用这两种催化剂组成双功能催化剂体系能够很方便地制得密度范围在０．９０－０．９３，Ｅｔ／１０００Ｃ在１０－４０的ＬＬＤＰＥ．

A STUDY OF DUAL CATALYST SYSTEM FOR ETHYLENE DIMERIZATION AND COPOLYMERIZATION

A process for ethylene dimerization to butene-1 and copolymerization of the in situ-formed olefin with ethylene using the dual catalyst systems, which consist of a dimerization catalyst Ti (OBu)_4 and a copolymerization catalyst TiCl_4/MgCl_2, has been developed . Such catalytic Systems allowed the synthesis of the linear low density polyethylene(LLDPE) from a single monomer source. The kinetic behaviours of ethylene dimerization were studied .Variations in the molar ratio of two catalysts and the pre-run time of the dimerization provide flexibility for changing the degree of branching of polyethylene and,as a consequence ,its physical properties such as crystallinity,density and melting point. The results show that the dual catalyat system used could easily produce LLDPE (D= 0.91 - 0. 93)with levels of 10 - 40 branches per 1000 carbon atoms.