New Cocatalyst for Alkene Polymerization Reactions with Transition Metal Catalysts

摘要

The effect of a cocatalyst in alkene homo- and copolymerizations with transition metal catalysts of different types was studied. The results of studies of polymerizations of ethylene, propylene, and higher linear 1-alkenes and copolymerizations of ethylene with linear 1-alkenes using catalysts of different types in combination with a binary cocatalyst Al(C_2H_5)_2Cl/Mg(C_4H_9)_2 at [Al] : [Mg] > 2.5 were summarized. The traditional Ziegler-Natta catalysts (TiCl_4, Ti(Oi-C_3H_7)_4, and TiCl_3 ) and titanium postmetallocene complexes with various organic ligands were studied. The binary cocatalyst significantly increased the activity of the traditional catalysts compared with that of Al(C_2H_5)_2Cl and the activity of postmetallocene complexes compared with that of polymethylaluminoxane (MAO). The active centers of these catalytic systems differ in their kinetic parameters, stereospecificity, and copolymerization ability. The efficiency of the Al(C_3H_5)_2Cl/Mg(C_4H_9)_2 cocatalyst can be explained by the in situ formation of finely dispersed MgCl_2 and immobilization of the cationic active centers on its surface.