The Research Of Novel Non-Metallocene Catalysts With Phenoxy-Imine Ligands For Ethylene Polymerization And Ethylene/Acrylonitrile Copolymerization

Phthaldialdehyde (ketone) was treated with substituted phenol to obtain ligands(L1-L4) which were then treated with transition metal halide, and obtained a series of novel non-metallocene catalysts(Cat.1-Cat.12). The structures of the ligands(L1-L4) were characterized by 1H-NMR and Elemental Analysis. These catalysts(Cat.1-Cat.12) were used to promote ethylene polymerization and ethylene/acrylonitrile copolymerization. The effects of the ligand structures and the metal center atoms(Ti, Zr) of these catalysts, polymetization temperature, Al/M molar ratio and concentration of catalyst on polymerization performance were investigated in detail. The structures and properties of polyethylene and ethylene/acrylonitrile copolymer obtained were characterized by WAXD, DSC,13C NMR, FT-IR and GPC. The main work in this thesis is composed of non-metallocene catalysts(Cat.1-Cat.12) synthesis, ethylene polymerization catalyzed by catalysts(Cat.1-Cat.12)/MAO and ethylene/acrylontrile copolymerization catalyzed by catalysts(Cat.4-Cat.12)/MAO. Firstly, Phthaldialdehyde(ketone) was treated with substituted phenol (2-amino-4-methylphenol,2-amino-5-methylphenol,2-amino-4-tert-butyl-Phenol) to obtain a series of ligands(L1-L4) which were then treated with transition metal halide(TiCl4, ZrCl4, YCl3), so that the novel non-metallocene catalysts(Cat.1-Cat.12) with phenoxy-imine ligands were obtained.Secondly, the catalysts(Cat.1-Cat.12)/MAO were employed in study on ethylene polymerization. The results indicated that the catalytic activity was greatly affected by the structures, metal center atoms of catalysts and reaction conditions. Besides, the catalytic activity of the catalyst(Cat.10) is the highest, up to 2.93×106 g PE/mol.Y.h, and the weight-average molecular weight of the polyethylene obtained was relative high, and its molecular weight distribution narrow(Mw=3.35×105 g/mol, MWD=1.84). It was also found that the catalytic activity of catalysts increased with enhancing temperature in the range of 40-60℃, peaking at 50℃. It also at first increased with the increasing of Al/M molar ratio and catalysts concentration and then decreaced, reaching the maximum value when Al/M molar ratio was 300, catalysts concentration 1.0×10-4mol/L. The results of 13C NMR and WAXD confirmed the linear structure of polyethylene obtained.Thirdly, ethylene/acrylonitrile copolymerization was catalyzed by the catalysts(Cat.4-Cat.12)/MAO. It was found that the catalyst(Cat.6) with early transition metal Ti as active centre had the strong capability of resistance to hetero atoms, so its catalytic activity was up to 1.77×104 g P/mol.Ti.h. WAXD, DSC results indicated that acrylonitrile incorporation content in copolymer increased with increasing of the acrylonitrile concentration of reaction system. The stereoregularity of polyethylene chain was demaged to some extent by the introduction of acrylonitrile unit, so the crystallinity, melting point(Tm) of copolymer were decreased.13C NMR and FT-IR results revealed that acrylonitrile content in molar of copolymer was up to 2.29%, acrylontrile unit was isolated in the copolymer chain homogeneously and there was no long sequence units which were good for performance homogenization of the whole copolymer molecular chain. GPC results showed that the Mw of copolymer was as high as 36500 g/mol, MWD less than 2, showing a single distribution.