New Catalysts for Ethylene Polymerization and Copolymerization Based on Ti(IV) Complexes with a Tetradentate Piperazine Ligand

Abstract

Two new catalyst systems for the synthesis of high molecular weight polyethylene and ethylene copolymers with linear 1-alkenes (1-hexene, 1-octene, 1-decene and 3-methyl-1-butene) are described. The catalysts are based on Ti(IV) complexes of the LTiX₂ type with a tetradentate bis(phenolate)- piperazine ligand L and with X = Cl or Oi-Pr. The complexes are activated with a bicomponent cocatalyst, a combination of Al(C₂H₅)₂Cl and Mg(C₄H₉)₂ at an [Al]/[Mg] molar ratio of ~3. The catalysts afford the synthesis of UHMW resins, both polyethylene and ethylene/1-alkene copolymers with a low 1-alkene content, as well as the synthesis of high molecular weight ethylene/1-alkene copolymers with the 1-alkene content of over 10 mol %.