Catalysis Of The Complex Containing Phosphinimide Titanium For Olefin Copolymerization

The discovery of metallocene-based catalysts processing extremely high activity in olefin polymerization marked a new epoch in polymer industry.Metallocene catalyst is the most prominent polymerization characteristics for high polymerization activity,narrow molecular weight distribution?MWD?,good control over copolymer composition distributions.But metallocene catalysts have disadvantage of complex synthetic route and poor stable on storage.It is difficult to cover the entire EP elastomer grade slate until now.Recent years,non-metallocene catalysts technique provides the possibility for developing more polyolefin elastomers of high performance.The work targeted on the controlled synthesis of ethylene-olefin elastomers with phosphinimide titanium catalysts.First,four kinds of phosphinimide titanium catalysts were synthesized and systematically studied for the ethylene-propylene and ethylene-propylene-diene solution copolymerization,which was performed in high pressure CSTR polymerization system.The ethylene-propylene copolymer with narrow MWD and well defined chain structure was obtained.With this remarkable cataysts,long chain branching copolymer and high molecular weight together with high-5-vinyl-2-norbornene ethylene propylene copolymers was synthesized successfully.The results are of great benefit to polyolefin elastomers in our country.The major achievements of this thesis include:?1?Six kinds of Ti-phosphinimideligand complexes were obtained with simple synthesis processaccording to some correlative literature.The process is easy to operate and results in higher yield.This complex has good solubility,good storage stability performance and is easily handled.It could be used with MAO or organoboron compounds as the inexpensive and highly efficient catalyst to polymerize the ethylene.?2?Ti-phosphinimidecomplexCatalystderivedthatincorporate one-cyclopentadienyl ligand proved to be high activity in ethylene-propylene copolymerization.The catalytic activity can reach 8.6×10⁶g/molTi.h under normal pressure.The dialkyl titanium complexes activated with[Ph₃C][B?C₆F₅?₄],gave catalysts that exhibited substantially higher activity and high molecular weight copolymer.The catalyst showed good sensitivity to hydrogen and polymer molecular weight could be regulated and controlled efficiently.¹³C-NMR was used to characterize the sequence distribution of copolymer,the reactivity ratio for this catalyst system were estimated as:rE=1.96,rP=0.55.The reactivity ratio may not vary much between ethylene and propylene.The product rErP=1.07 indicates a random distribution of comonomer units.Phosphinimide catalyst systems produced has a substantially improved heat stability than Ziegler Natta?ZN?and metallocene catalysts.The catalyst has very high catalyst productivity which has rather commercial promising prospects.?3?Terpolymerizations of ethylene-propylene-5-ethylidene-2-norbornene?ENB?were carried out with Ti-phosphinimide catalyst.The terpolymer obtained has narrow molecularweightdistributionandveryhighENBcontent.Ehylene-propylene-5-vinyl-2-norbornene?VNB?terpolymers with 3wt%VNB content were also synthesized using this catalyst.It overcomes the classical problem of excessive reactor fouling due to highly branched products in the case of high VNB contents.?4?By introducing a fourth monomer VNB,which has two reactive double bonds,a series of ethylene-propylene quadripolymer were prepared.The hyper branched structure was confirmed by ¹³C-NMR and its viscoelastic behavior was measured using a dynamic mechanical measurement RPA2000.?5?A maximum activity of 3.25×10⁶g PP/molTi·h was attained using half-titanocenes containing a phosphinimide ligand in the presence of methylaluminoxane?MAO?or[Ph₃C][B?C₆F₅?₄].Meanwhile,a highest molecular weight of M_w=4.42×10⁵ with a molecular weight distribution of 1.73 was reached.The sequence distribution of the polymers was also measured using ¹³C-NMR analyses.The PPs obtained with the half-titanocene catalysts were a kind of more and less syndiotactically enriched atactic PPs with r?62.28%?higher than m?37.72%?.A value of[mr/?2mm+mr?]+[mr/?2rr+mr?]is 1.04,meaning the polymerization in agreement with the statistical model of Bernoullian.?6?Ethylene-propylene copolymers were prepared using phosphinimide catalyst to achieve higher levels of control over sequential structure,composition and molecular weight distribution.Since the catalyst is highly efficient,the process does not require a metals removal or de-ashing step.In addition,the copolymers produced have narrow molecular weight distribution for good thickening efficiency and shear stability of high temperature as well as low-temperature fluidity.Therefore,it can be used as top quality lubricating oil viscosity index.?7?Terpolymers of ethylene-propylene-diene produced have good mechanical property and processing property.They could offer improved product appearance at higher extrusion outputs.The suitable extrusion temperature is from 90?to 110?for extruded products.The vulcanized rubbers have tensile strength of 11 MPa,elongation at break is above 400%,and have the smallest permanent deformation,good elastic resilience among the samples investigated.So it can meet the automotive sealing strip requirement for appearance and mechanical properties.