The investigation of novel non‐metallocene catalysts with phenoxy‐imine ligands for ethylene (co‐)polymerization

Phthaldialdehyde and phthaldiketone were treated with substituted phenols of 2‐amino‐4‐methylphenol, 2‐amino‐5‐methylphenol and 2‐amino‐4‐t‐butylphenol, respectively, and then treated with transition metal halides of TiCl₄, ZrCl₄ and YCl₃. A series of novel non‐metallocene catalysts (1–12) with phenoxy‐imine ligands was obtained. The structures and properties of the catalysts were characterized by ¹H NMR and elemental analysis. The catalysts (1–12) were used to promote ethylene (co‐)polymerization after activation by methylaluminoxane. The effects of the structures and center atoms (Ti, Zr and Y) of these catalysts, polymerization temperature, Al/M (M = Ti, Zr and Y) molar ratio, concentration of the catalysts and solvents on the polymerization performance were investigated. The results showed that the catalysts were favorable for ethylene homopolymerization and copolymerization of ethylene with 1‐hexene. Catalyst 10 is most favorable for catalyzing ethylene homopolymerization and copolymerization of ethylene with 1‐hexene, with catalytic activity up to 2.93 × 10⁶ gPE (mol Y)^?1 h^?1 for polyethylene (PE) and 2.96 × 10⁶ gPE (mol Y)^?1 h^?1 for copolymerization of ethylene with 1‐hexene under the following conditions: polymerization temperature 50 °C, Al/Y molar ratio 300, concentration of catalyst 1.0 × 10^?4 L^?1 and toluene as solvent. The structures and properties of the polymers obtained were characterized by Fourier transform infrared spectroscopy, ¹³C NMR, wide‐angle X‐ray diffraction, gel permeation chromatography and DSC. The results indicated that the obtained PE catalyzed by 4 had the highest melting point of 134.8 °C and the highest weight‐average molecular weight of 7.48 × 10⁵ g mol^?1. The copolymer catalyzed by 4 had the highest incorporation of 1‐hexene, up to 5.26 mol%, into the copolymer chain. © 2012 Society of Chemical Industry