Synthesis Of Phenoxy-ester Ligated Titanium Complex And Their Catalytic Properties

Ethylene propylene rubber(EPR) is a type of synthetic elastomer of ethylene-propylene copolymer and ethylene-propylene-diene-terpolymer rubber. EPR is the fastest growing synthetic rubber since the 1980 s. Its output and consumption ranks the third of the world’s seven big synthetic rubber varieties after styrene-butadiene rubber and polybutadiene rubber. It is no surprise that EPR is widely used in automobile industry, construction and other fields due to its excellent aging resistance(ozone resistance, heat resistance, and weather resistance), chemical attack resistance, good electrical insulating properties and low density.The key of ethylene propylene copolymerization technology lies in the catalysts. Based on the new concept of “ligand-oriented catalyst design”, series of ligands were prepared by introduction of substituents with different space steric hindrance and electronic effect to phenoxy-ester(a kind of electron donor) matrix. The novel non-metallocene single-site catalysts--[O, O] bidentate coordination compounds were then obtained by the reaction of these ligands and TiCl4. Finally catalytic activities of as-prepared catalysts for ethylene propylene(co) polymerization were studied. The structures of polyolefins were also characterized.Firstly, 2, 6-dibromo-4-methyl phenol was used as a starting material and treated with silane in the first step to prepare phenoxy silane compounds(precursors) with the yield of above 95%. Then precursors were reacted with chloro-carbonic ester to obtain 6 kinds of phenoxy-ester ligands(L1~L6) containing different substituents with the yield of about 40%. The structures of precursors and ligands were characterized using infrared spectrometer(FT-IR), nuclear magnetic resonance and mass spectrum(MS).Secondly, the ligands of L1~L6 were reacted with titanium tetrachloride respectively in the presence of n-butyl lithium in order to obtain six phenoxy-ester ligated titanium complexes of C1~C6. The structures of the complexes were characterized by FT-IR and MS.Finally, titanium complexs were used as the catalysts for ethylene propylene(co)polymerization together with iBu3A1/Ph3CB(C6F5)4 as the cocatalyst in n-hexane. It was found that the as-prepared catalysts could catalyze polymerization and copolymerization of ethylene and propylene. The C5 showed the highest catalytic activity of 7221.06 g EPC/(g Ti·h) when the volume flow ratio of ethylene/propylene was 1/3. As-obtained polypropylene and ethylene propylene copolymer were random copolymers, and the glass transition temperatures of the copolymers were-14.3 and-46.3 oC, respectively. The link ratios of ethylene to propylene for EPR prepared using catalysts C1~C6 were between 0.728 and 1.133. The link ratios of ethylene to propylene in the copolymers were declined with the decrease of ethylene content in the feeding ratios. The ethylene propylene copolymer synthesized using the C6 catalyst had the largest weight-average molecular weight of 2.86×105.