Metal complex, preparation method thereof and olefin polymerization method

Abstract

The invention discloses a metal complex, a preparation method thereof and an olefin polymerization method. The structural formula of the metal complex is # imgabs0 #. The metal complex has the advantages that (1) the adjustability is strong: by changing the electronic effect and the volume effect of R1-R8 groups, the catalyst shows excellent catalytic activity and thermal stability when ethylene and alpha-olefin are copolymerized; (2) a single active center: a polymerized product has good uniformity which is mainly shown in relatively narrow molecular weight distribution and uniform distribution of a comonomer in a main chain of the polymer; and (3) good monomer selectivity: because the catalyst has strict symmetry, the catalyst shows good stereoselectivity and regioselectivity, and is beneficial to the insertion rate and regularity of co-monomers.

Description

Technical Field

[0001] The present invention relates to a metal complex, and particularly to a metal complex and a preparation method thereof, and the application of a catalyst system composed of the metal complex in the field of olefin polymerization. Background Art

[0002] Polyolefin elastomers are copolymers of olefins and α-olefins catalyzed by metallocenes, which have plasticity and high elasticity and can be widely used in fields such as films, fibers, pipes, cables, machine tools, seals, photovoltaics, hot melt adhesives, etc. There are still some defects in metallocene-catalyzed polymerization reactions, and there are still problems to be solved in industrial applications, such as high synthesis costs and difficult resin processing. Therefore, the research direction has been placed on other non-metallocene single-site catalysts. Based on the research on metallocene catalysts, people have understood the role of the cyclopentadiene group in the catalyst ligand in the whole catalytic process: controlling the stereoselectivity and electron-donating properties of the catalytic active center and preventing the formation of a second active center that broadens the polymer molecular weight distribution. Many organic groups can also play this role, so non-metallocene complex catalysts are derived. The ligand skeleton of non-metallocene catalysts does not contain cyclopentadiene, indenyl or fluorenyl groups, and the ligand is composed of alkyl or aryl groups containing heteroatoms such as N, O, S, P, etc. In terms of catalytic performance, non-metallocene catalysts have reached or exceeded metallocene catalysts. Among them, non-metallocene catalysts with group IVB metals as the ligand center are the most numerous.

[0003] Dow Chemical (Dow) and ExxonMobil Corporation (Exxon) respectively introduced metallocene catalysts with constrained geometry (shown in the following formulas 1, 2, 3) in a number of published patents (US5064802, EP0416815A2, US5026798, US 5057475) for the random copolymerization of ethylene and α-olefins. Their comonomer insertion rate is low, the catalyst activity is poor, and the molecular weight of the copolymer is low. In response to the challenges posed by scientific research progress, it is urgent to develop a non-metallocene catalyst with strong controllability, a single active center and excellent monomer selectivity (improving the monomer insertion rate).

[0004] Summary of the Invention

[0005] The present invention provides a metal complex and a preparation method thereof. When the metal complex is used in olefin polymerization, especially in olefin / α-olefin copolymerization, it has high catalytic activity, not only a high comonomer insertion rate, but also strong controllability and excellent monomer selectivity, which can significantly improve the reaction rate and is conducive to obtaining polymer products with a higher molecular weight and a narrower molecular weight distribution.

[0006] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0007] A metal complex having the following structural formula:

[0008]

[0009] Wherein,

[0010] R 1 and R 8 are each independently selected from hydrogen, halogen or the following groups: C 1-6 alkyl, C 1-6 alkoxy, C 3-10 cycloalkyl, C 6-14 aryl, C 6-14 aryloxy;

[0011] R 2 , R 3 , R 6 , R 7 are the same as or different from each other and are each independently selected from hydrogen, halogen or the following groups: C 1-6 alkyl, C 1-6 alkoxy, C 3-10 cycloalkyl, C 6-14 aryl, C 6-14 aryloxy;

[0012] R 4 and R 5 are each independently selected from hydrogen, halogen or the following groups: C 1-6 alkyl, C 1-6 alkoxy, C 3-10 cycloalkyl, C 6-14 aryl, C 6-14 aryloxy;

[0013] X is a monovalent ligand group having 1 to 20 atoms other than hydrogen, or a divalent ligand group having 1 to 40 atoms;

[0014] M is selected from Group IVB metals, preferably titanium, zirconium or hafnium.

[0015] In a preferred embodiment, in Formula I, R 1 and R 8 are selected from the groups: methyl, methoxy, tert-butyl, cyclohexyl;

[0016] Meanwhile, R 2 , R 3 , R 6 , R 7 are the same as or different from each other and are each independently selected from the groups: methyl, ethyl, tert-butyl, methoxy, ethoxy;

[0017] Meanwhile, R 4 and R 5Selected from hydrogen;

[0018] Meanwhile, X is halogen, methyl, or benzyl;

[0019] Meanwhile, M is selected from titanium, zirconium, or hafnium.

[0020] The method for preparing the metal complex of the present invention comprises the following steps:

[0021] (I) In a super-dry organic solvent, directly complex the compound shown in Formula II with a metal halide to obtain a metal complex with X being halogen; or,

[0022] (II) In a super-dry organic solvent, directly complex the compound shown in Formula II with a metal halide, and then add a Grignard reagent to react to obtain a metal complex with X being methyl or benzyl;

[0023] As a preferred embodiment, in the step (I), the temperature of the complexation reaction is 60 - 100 °C, such as 60 °C, 70 °C, 80 °C, 90 °C, 180 °C, and the reaction time is 4 - 12 h to obtain the complex shown in Formula I.

[0024] As a preferred embodiment, in the step (II), the temperature of the complexation reaction is 60 - 100 °C, such as 60 °C, 70 °C, 80 °C, 90 °C, 180 °C, and the reaction time is 4 - 12 h; then add a Grignard reagent and continue to react at -10 - 0 °C for 1 - 3 h, such as 1 h, 2 h, 3 h, to obtain the complex shown in Formula I.

[0025]

[0026] In the Formula II, the definition of R 1 –R 8 is the same as that in Formula I.

[0027] The super-dry organic solvent of the present invention is one or more of toluene, xylene, ether, tetrahydrofuran, n-hexane, and n-heptane.

[0028] The metal halide of the present invention is a Group IVB metal halide, preferably one or more of chlorides, bromides, and iodides of Group IVB metals.

[0029] The Grignard reagent of the present invention is one or more of methylmagnesium bromide, methylmagnesium chloride, benzylmagnesium bromide, and benzylmagnesium chloride.

[0030] Further, the molar ratio of the compound shown in Formula II to the metal halide is 1:(0.5 - 1), such as 1:0.5, 1:0.6, 1:0.8; or, the compound prepared from the metal halide is further added with a Grignard reagent for reaction, and the molar ratio of the compound shown in Formula II to the metal halide and the Grignard reagent is 1:(0.5 - 1):(2 - 2.3), such as 1:0.5:2, 1:0.6:2.2, 1:0.8:2.3;

[0031] Further, the compound shown in Formula II is prepared by the following steps:

[0032] 1) In an ultra-dry organic solvent, in the presence of an inorganic base and 1,2-dibromomethane, the compound shown in Formula III and the compound shown in Formula IV react to obtain the compound shown in Formula V;

[0033] The compound of Formula III is preferably one or more of 2,5-di-tert-butylphenol, 2,5-dimethoxyphenol, 2-methyl-5-tert-butylphenol, 2-tert-butyl-5-methoxyphenol.

[0034] The compound of Formula IV is preferably one or more of 2,5-di-tert-butylaniline, 2,5-dimethoxyaniline, 2-methyl-5-tert-butylaniline, 2-tert-butyl-5-methoxyaniline.

[0035] Preferably, the inorganic base is one or more of cesium carbonate, potassium carbonate, potassium hydroxide, sodium hydroxide.

[0036] Preferably, the organic solvent is one or more of acetonitrile, tetrahydrofuran, N,N-dimethylformamide.

[0037] Preferably, the molar ratio of the compound of Formula III, the compound of Formula IV, the inorganic base, and 1,2-dibromomethane is 1:1:(2 - 5):(0.4 - 0.6), such as 1:2:0.5, 1:3:0.6, 1:4:0.6, 1:5:0.5.

[0038] The preferred reaction conditions are: the reaction temperature is 0°C to 80°C, such as 0°C, 20°C, 40°C, 50°C, 60°C, 80°C, and the reaction time is 0.5 - 2 h, such as 0.5 h, 1 h, 2 h.

[0039] 2) In an ultra-dry organic solvent, in the presence of an organic base, the compound shown in Formula V reacts with iodomethane to form the compound shown in Formula II.

[0040] Preferably, the organic base is one or more of triethylamine, diisopropylethylamine, lithium diisopropylamide, lithium hexamethyldisilazide, sodium hexamethyldisilazide.

[0041] Preferably, the organic solvent is acetone, tetrahydrofuran, N,N-dimethylformamide.

[0042] Preferably, the molar ratio of the compound of formula V, the organic base, and methyl iodide is 1:(1.5 - 3):(1 - 1.5); for example, 1:2:1, 1:3:1.2, 1:2:1.3, 1:3:1.5.

[0043] The preferred reaction conditions are: the reaction temperature is from 0°C to 80°C, such as 0°C, 20°C, 40°C, 50°C, 60°C, 80°C, and the reaction time is 0.5 - 2 h, such as 0.5 h, 1 h, 2 h.

[0044] The reaction formula of the above reaction process is as follows:

[0045]

[0046] The present invention also provides an application of the metal complex in olefin polymerization, especially in the copolymerization of ethylene and α-olefins.

[0047] The α-olefins include propylene, butene, octene, etc.

[0048] The application method of the metal complex in the olefin polymerization reaction, wherein the metal complex is used as the main catalyst and co-catalyzes the olefin polymerization reaction with a co-catalyst.

[0049] The co-catalyst is one or more of methylaluminoxane, ethylaluminoxane, butylaluminoxane, methylethylaluminoxane, and boron salt compounds; preferably methylaluminoxane.

[0050] The olefin polymerization temperature is 20 - 250°C, such as 20°C, 40°C, 60°C, 80°C, 100°C, 120°C, 150°C, 180°C, 200°C, 220°C, 250°C, preferably 80 - 150°C, more preferably 80 - 120°C, and the polymerization pressure is 0.1 - 10 MPa, such as 0.1 MPa, 0.5 MPa, 2 MPa, 3 MPa, 5 MPa, 7 MPa, 8 MPa, 10 MPa, preferably 1 - 3 MPa.

[0051] The molar ratio of aluminum in the co-catalyst to the central metal M of the metal complex, Al / M, is 4 - 300, such as 5, 10, 20, 50, 80, 100, 120, 150, 170, 200, preferably 50 - 150.

[0052] The metal complex of the present invention modifies the ligand through an electron-donating group to increase the strength of the coordination bond, and the introduced heteroatom has a lone pair of electrons to further enhance the bonding force between the two.

[0053] Compared with the prior art, the present invention has the following technical advantages:

[0054] (1) Strong controllability: By changing the electronic effect and steric effect of the R 1 -R 8 group, the catalyst exhibits excellent catalytic activity and thermal stability during the copolymerization of ethylene and α-olefin.

[0055] (2) Single active center: The polymerized product has good uniformity, mainly manifested in a relatively narrow molecular weight distribution and uniform distribution of comonomers in the polymer main chain.

[0056] (3) Good monomer selectivity: Because the catalyst has strict symmetry, it shows good stereoselectivity and regioselectivity, which is beneficial to the insertion rate and regularity of comonomers. Detailed implementation mode

[0057] The present invention will be further described below through specific examples. The examples described in the present invention are only for the illustration of the present invention and do not limit the scope of the present invention.

[0058] The experimental methods used in the following examples are all conventional methods unless otherwise specified.

[0059] The concentrations in the following examples are all molar concentrations unless otherwise specified.

[0060] The materials, reagents, etc. used in the following examples can all be obtained from commercial sources, and the main sources are as follows:

[0061] 2,5-Di-tert-butylphenol: AR, Innochem

[0062] 2,5-Di-tert-butylaniline: AR, Innochem

[0063] n-Butyllithium: AR, Innochem

[0064] Iodomethane: AR, Innochem

[0065] 1,2-Dibromomethane: AR, Innochem

[0066] Ultra-dry tetrahydrofuran: AR, Innochem

[0067] Cesium carbonate anhydrous: AR, Innochem

[0068] Potassium hydroxide anhydrous: AR, Innochem

[0069] Triethylamine: AR, Innochem

[0070] Methanol anhydrous: AR, Innochem

[0071] Ethyl acetate: AR, Innochem

[0072] Ultra-dry toluene: AR, Innochem

[0073] Ultra-dry n-hexane: AR, Innochem

[0074] Petroleum ether: 60 - 90 °C, Beijing Chemical Reagent Company

[0075] Silica gel: AR, 200 - 300 mesh, Shanghai Wusi Chemical Reagent Company

[0076] Chloroform-d: AR, Acros

[0077] Industrial alcohol: 95%, Beijing Chemical Reagent Company

[0078] ZrCl 4 (THF) 2 : Tokyo Chemical Industry Co., Ltd.

[0079] HfCl 4 (THF) 2 : Tokyo Chemical Industry Co., Ltd.

[0080] MAO (alkylaluminoxane), MMAO (modified alkylaluminoxane): 10 wt% toluene solution, Albemarle

[0081] Ethylene: 99.9%, Beijing Yanshan Chemical Co., Ltd.

[0082] 1-Octene: 98%, Beijing InnoChem Science & Technology Co., Ltd.

[0083] High-purity nitrogen: Beijing Shun'an Qite Gas Co., Ltd.

[0084] Liquid nitrogen: Beijing Shun'an Qite Gas Co., Ltd.

[0085] Isopar E: ExxonMobil

[0086] Other raw materials and reagents, if not otherwise specified, are obtained through commercial channels.

[0087] In the following ethylene polymerization examples, the molecular weight and molecular weight distribution of the obtained polymers were measured by PL-GPC220 at 150 °C. Three PLgel 10μm MIXED-B separation columns in series were used, and 1,2,4-trichlorobenzene was used as the solvent. The melting points of the polymers were all determined by the conventional DSC (Q2000) method, and the polymerization activities of the polymers were all calculated according to the following formula: Polymerization activity = Polymer mass / (Metal content in the catalyst · Polymerization time). The calculation method of the 1-octene insertion rate refers to the reference (Macromolecules 1999, 32, 3817). The compounds in the following examples were characterized by a nuclear magnetic resonance spectrometer (Brucker ARX-400). The high-temperature nuclear magnetic of the polymer was obtained by testing with a Bruker DMX 300MHz at 120 °C using deuterated 1,1,2,2-tetrachloroethane as the solvent.

[0088] The present invention will be described in detail below in conjunction with examples, but the present invention is not limited to the following examples.

[0089] Note: In the examples, eq represents molar equivalent. For example, 1eq represents 1 molar equivalent.

[0090] The synthesis of the complexes in the following examples was carried out according to the following reaction equations:

[0091]

[0092] Example 1 Synthesis of catalyst 4, where M is Ti

[0093] (1) Preparation of compound 1:

[0094] Dissolve 1,2-di-tert-butylphenol (10 g, 0.05 mol, 1eq) and 1,2-di-tert-butylaniline (10 g, 0.05 mol, 1eq) in 200 mL of ultradry acetonitrile. Add potassium hydroxide (8.4 g, 0.15 mol, 3eq) at room temperature, and then dropwise add 1,2-dibromomethane (4.2 g, 0.025 mol, 0.5eq). React at 80 °C for 2 h until the reaction is completed. Slowly return to room temperature and quench with 100.0 mL of water. Rotate and evaporate to concentrate the reaction solution, extract with ethyl acetate and then rotate and evaporate. Recrystallize and wash with n-hexane to obtain 10 g of white solid, with a yield of 50.1%.

[0095] The nuclear magnetic structure confirmation data of compound 1 are shown as follows:

[0096] 1H NMR (500MHz, CDCl 3)δ 7.13 (t, J = 3.0 Hz, 1H), 6.87 (t, J = 3.0 Hz, 1H), 6.80 (d, J = 2.9 Hz, 2H), 6.69 (d, J = 3.0 Hz, 2H), 5.85 (s, 1H), 5.80 (s, 1H), 4.00 (s, 1H), 1.41 (s, 18H), 1.32 (s, 18H).

[0097] (2) Preparation of Compound 2:

[0098] Dissolve Compound 1 (10 g, 0.024 mol, 1 eq) in 100 mL of tetrahydrofuran. Dropwise add triethylamine (4.8 g, 0.048 mol, 2 eq) at 0 °C, maintain the temperature and react for 0.5 h. Then dropwise add methyl iodide (3.7 g, 0.026 mol, 1.1 eq) and react at 80 °C for 2 h until the reaction is completed. Slowly restore to room temperature, add 100.0 mL of water to quench, rotary evaporate and concentrate the reaction solution, extract with ethyl acetate and then rotary evaporate, recrystallize with n - hexane and wash to obtain 5 g of a pale yellow solid, with a yield of 49.5%.

[0099] The NMR structural confirmation data of Compound 2 are as follows:

[0100] 1H NMR (500 MHz, CDCl 3 )δ 7.13 (t, J = 3.0 Hz, 1H), 6.79 (dd, J = 6.3, 3.0 Hz, 3H), 6.75 (d, J = 2.9 Hz, 2H), 5.99 (s, 1H), 5.42 (s, 1H), 3.02 (s, 3H), 1.41 (s, 18H), 1.32 (s, 18H).

[0101] (3) Preparation of Catalyst 4:

[0102] In the glove box, dissolve 5 g of Compound 2 (5 g, 0.01 mol, 1 eq) in 50 mL of dry toluene, then add TiCl 4 (1.1 g, 0.005 mol, 0.5 eq), heat to 90 °C and reflux for 4 h. After the reaction is completed, pump dry the toluene, add 15 mL of dry n - hexane, stir for 15 min and then let stand, filter and wash with dry n - hexane. Pump dry the filtrate, add 20 mL of dry toluene, filter and collect the filtrate. After pumping dry the solvent, obtain 2.5 g of a light red solid, with a yield of 48.6%.

[0103] The NMR structural confirmation data of Catalyst 4 are as follows:

[0104] 1H NMR (500 MHz, CDCl 3)δ 7.13 (t, J = 3.0 Hz, 1H), 6.79 (dd, J = 6.3, 3.0 Hz, 3H), 6.75 (d, J = 2.9 Hz, 2H), 5.5 (s, 1H), 5.3 (s, 1H), 3.01 (s, 1H), 2.82 (s, 1H), 2.83 (s, 1H), 1.41 (s, 18H), 1.32 (s, 18H).

[0105] Example 2 Preparation of Catalyst 8, M is Ti, X is -CH 3

[0106] The preliminary experimental steps of this example are the same as those of Example 1. The difference is that in this example, methylmagnesium bromide is used to further modify Catalyst 4. The specific modification process is as follows: In the glove box, 2.5 g of Catalyst 4 (2.5 g, 0.0025 mol, 1.0 eq) is dissolved in 40 mL of dry toluene, and a toluene solution of 3 mol / L methylmagnesium bromide (0.66 ml, 0.005 mol, 2.0 eq) is slowly added dropwise. After reacting at 25 °C for 3 h, the mixture is filtered and the filtrate is collected. After drying the solvent, 1.5 g of a light red solid is obtained, and the yield is 62.3%.

[0107] The NMR structural confirmation data of Catalyst 8 are as follows:

[0108] 1H NMR (500 MHz, CDCl 3 )δ 7.13 (t, J = 3.0 Hz, 1H), 6.79 (dd, J = 6.3, 3.0 Hz, 3H), 6.75 (d, J = 2.9 Hz, 2H), 5.5 (s, 1H), 5.3 (s, 1H), 3.01 (s, 1H), 2.82 (s, 1H), 2.83 (s, 1H), 1.41 (s, 18H), 1.32 (s, 18H), -0.2 (s, 3H), -0.22 (s, 3H).

[0109] Example 3 Preparation of Catalyst 9, M is Zr, X is -CH 3

[0110] The experimental steps of this example are basically the same as those of Example 2. The difference is that in this example, ZrCl 4(1.33 g, 0.005 mol, 0.5 eq) was used to prepare catalyst 5, and methylmagnesium bromide was used to further modify catalyst 5. The specific modification process was as follows: Inside the glove box, 2.5 g of catalyst 5 (2.5 g, 0.0024 mol, 1.0 eq) was dissolved in 40 mL of dry toluene. A toluene solution of 3 mol / L methylmagnesium bromide (0.65 mL, 0.0048 mol, 2.0 eq) was slowly added dropwise. After reacting at 25 °C for 3 h, the mixture was filtered and the filtrate was collected. After drying the solvent, 1.5 g of a light red solid was obtained, and the yield was 62.5%.

[0111] The NMR structure confirmation data of catalyst 9 are shown as follows:

[0112] 1H NMR (500 MHz, CDCl 3 ) δ 7.13 (t, J = 3.0 Hz, 1H), 6.79 (dd, J = 6.3, 3.0 Hz, 3H), 6.75 (d, J = 2.9 Hz, 2H), 5.5 (s, 1H), 5.3 (s, 1H), 3.01 (s, 1H), 2.82 (s, 1H), 2.83 (s, 1H), 1.41 (s, 18H), 1.32 (s, 18H), -0.2 (s, 3H), -0.22 (s, 3H).

[0113] Preparation of catalyst 10 in Example 4, M is Hf, X is -CH 3

[0114] The experimental procedure of this example was basically the same as that of Example 2, except that in this example, HfCl 4 (1.8 g, 0.005 mol, 0.5 eq) was used to prepare catalyst 6, and methylmagnesium bromide was used to further modify the metal complex. The specific modification process was as follows: Inside the glove box, 2.5 g of catalyst 6 (2.5 g, 0.0022 mol, 1.0 eq) was dissolved in 40 mL of dry toluene. A toluene solution of 3 mol / L methylmagnesium bromide (0.61 mL, 0.0044 mol, 2.0 eq) was slowly added dropwise. After reacting at 25 °C for 3 h, the mixture was filtered and the filtrate was collected. After drying the solvent, 1.1 g of a light red solid was obtained, and the yield was 45.6%.

[0115] The NMR structure confirmation data of catalyst 10 are shown as follows:

[0116] 1H NMR (500 MHz, CDCl 3)δ 7.13 (t, J = 3.0 Hz, 1H), 6.79 (dd, J = 6.3, 3.0 Hz, 3H), 6.75 (d, J = 2.9 Hz, 2H), 5.5 (s, 1H), 5.3 (s, 1H), 3.01 (s, 1H), 2.82 (s, 1H), 2.83 (s, 1H), 1.41 (s, 18H), 1.32 (s, 18H), -0.2 (s, 3H), -0.22 (s, 3H).

[0117] Example 5 Copolymerization of ethylene / 1-octene using catalyst 4 / MAO

[0118] The ampoule containing the weighed complex 4 (1 μmol), temperature sensor, cooling reflux device, and 1 L high-pressure reactor with mechanical stirring were continuously dried at 120 °C for 1 hour, evacuated, and gradually cooled to 25 °C. 100 mL of a 0.002 mol / L Isopar E dilution of MAO (0.2 mmol), 100 mL of 1-octene were added, and the temperature was raised to 120 °C. Ethylene monomer at 3.0 MPa was introduced, the ampoule was broken, and the polymerization reaction started. Throughout the polymerization process, the stirring rate, polymerization temperature, and ethylene pressure remained constant. After 15 min, the gas in the reactor was evacuated, the reaction solution was neutralized with an industrial alcohol solution acidified with 5% hydrochloric acid, the polymer precipitate was obtained and washed several times, and then dried to a constant weight under vacuum and weighed. 35 g of polymer was obtained, Al / Ti = 200, and the catalytic activity was 1.4×10 8 g mol -1 (Ti) h -1 ,M w = 1.42×10 5 g mol -1 ,PDI = 1.6,T m = 80.6 °C, and the 1-octene insertion rate was 53.5 wt%. Among them, PDI represents the molecular weight distribution coefficient, and M w represents the weight-average molecular weight.

[0119] Example 6 Copolymerization of ethylene / 1-octene using catalyst 5 / MAO

[0120] The polymerization reaction process was basically the same as in Example 5, except that the main catalyst was changed to complex 5. 46.23 g of polymer was prepared, and the catalytic activity was 1.85×10 8 g mol -1 (Zr) h -1 ,M w = 1.79×10 5 g mol -1 ,PDI = 1.8,T m = 83 °C, and the 1-octene insertion rate was 60.1 wt%.

[0121] Example 7 Copolymerization of ethylene / 1-octene catalyzed by catalyst 6 / MAO

[0122] The polymerization process was basically the same as that in Example 5, except that: the main catalyst was changed to complex 6, the polymerization time was 30 min, and the polymerization pressure was 1 Mpa. 79 g of polymer was obtained, and the catalytic activity was 1.58×10 8 g mol -1 (Hf)h -1 , M w = 1.53×10 5 g mol -1 , PDI = 2.2, T m = 85 °C, and the 1-octene insertion rate was 56.4 wt%.

[0123] Example 8 Copolymerization of ethylene / 1-octene catalyzed by catalyst 8 / MMAO

[0124] The polymerization process was basically the same as that in Example 5, except that: the main catalyst was changed to complex 8, the cocatalyst was changed to 0.002 mol / L MMAO (100 mL), the polymerization temperature was 200 °C, and the polymerization pressure was 5 MPa. 32.1 g of polymer was obtained, and the catalytic activity was 1.28×10 8 g mol -1 (Ti)h -1 , M w = 1.35×10 5 gmol -1 , PDI = 2.5, T m = 73.1 °C, and the 1-octene insertion rate was 57.1 wt%.

[0125] Example 9 Copolymerization of ethylene / 1-octene catalyzed by catalyst 9 / MAO

[0126] The polymerization process was basically the same as that in Example 8, except that: the main catalyst was changed to complex 7B, the addition amount of 0.002 mol / L MAO solution was changed to 50 mL, the reaction temperature was 180 °C, and the polymerization time was 5 min. 17.67 g of polymer was obtained, and the catalytic activity was 2.12×10 8 g mol -1 (Zr)h -1 , M w = 1.56×10 5 g mol -1 , PDI = 2.3, T m = 71.4 °C, and the 1-octene insertion rate was 58.5 wt%.

[0127] Example 10 Copolymerization of ethylene / 1-octene catalyzed by catalyst 10 / MMAO

[0128] The polymerization process was basically the same as that in Example 8, except that the main catalyst was changed to Complex 10, the addition amount of 0.002 mol / L MMAO solution was changed to 25 mL, the polymerization temperature was 180 °C, and the polymerization pressure was 5 MPa. 58.2 g of polymer was obtained, and the catalytic activity was 2.33×10 8 g mol -1 (Zr)h -1 , M w = 1.74×10 5 g mol -1 , PDI = 2.6, T m = 81.6 °C, and the 1-octene insertion rate was 57.9 wt%.

[0129] Comparative Example

[0130] Ethylene / 1-octene copolymerization was catalyzed with dimethylsilylene bis(indenyl)zirconium dichloride as the main catalyst:

[0131] The polymerization process was basically the same as that in Example 5, except only that the main catalyst was changed to dimethylsilylene bis(indenyl)zirconium dichloride, and 7.78 g of polymer was obtained, and the catalytic activity was 0.31×10 8 g mol -1 (Zr)h -1 , M w = 0.43×10 5 g mol -1 , PDI = 3.2, T m = 100 °C, and the 1-octene insertion rate was 18.5 wt%.

[0132] Table 1. Test results of ethylene / 1-octene copolymerization performance

[0133]

[0134] From the above examples and comparative examples, it can be seen that the polymerization catalytic system of the complex and the cocatalyst described in the present invention has good synergistic effects, showing a relatively high comonomer insertion rate, copolymerization activity, and thermal stability; and the molecular weight distribution is relatively narrow.

[0135] The above is only the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the method of the present invention, several improvements and supplements can still be made, and these improvements and supplements should also be regarded as the protection scope of the present invention.

Claims

1. A metal complex having the following structural formula: Wherein, R 1 and R 8 are each independently selected from hydrogen, halogen or the following groups: C 1-6 alkyl, C 1-6 alkoxy, C 3-10 cycloalkyl, C 6-14 aryl, C 6-14 aryloxy; R 2 、R 3 、R 6 、R 7 are independently selected from hydrogen, halogen or the following groups: C 1-6 alkyl, C 1-6 alkoxy, C 3-10 cycloalkyl, C 6-14 aryl, C 6-14 aryloxy; R 4 and R 5 are each independently selected from hydrogen, halogen or the following groups: C 1-6 alkyl, C 1-6 alkoxy, C 3-10 cycloalkyl, C 6-14 aryl, C 6-14 aryloxy; X is a monovalent ligand group having 1 to 20 atoms other than hydrogen, or a divalent ligand group having 1 to 40 atoms; M is selected from Group IVB metals, preferably titanium, zirconium or hafnium.

2. The metal complex according to claim 1, characterized in that, In the formula I, R 1 , R 8 are independently selected from the following groups: methyl, methoxy, tert-butyl, cyclohexyl; R 2 、R 3 、R 6 、R 7 are independently selected from the following groups: methyl, ethyl, tert-butyl, methoxy, ethoxy; R 4 、R 5 is hydrogen; X is selected from halogen, methyl, benzyl; M is selected from titanium, zirconium or hafnium.

3. A method for preparing the metal complex according to claim 1, comprising the following steps: (I) In a super-dry organic solvent, directly complex the compound shown in Formula II with a metal halide to obtain a metal complex with X being halogen; or, (II) In a super-dry organic solvent, directly complex the compound shown in Formula II with a metal halide, and then add a Grignard reagent to react to obtain a metal complex with X being methyl or benzyl; 4. The method according to claim 3, characterized in that, the metal halide is a Group IVB metal halide, preferably one or more of chlorides, bromides, iodides of Group IVB metals; the Grignard reagent is one or more of methylmagnesium bromide, methylmagnesium chloride, benzylmagnesium bromide, benzylmagnesium chloride.

5. The method according to claim 4, characterized in that, the molar ratio of the compound shown in Formula II to the metal halide is 1:(0.5 - 1); or, the molar ratio of the compound shown in Formula II to the metal halide and the Grignard reagent is 1:(0.5 - 1):(2 - 2.3).

6. The method according to claim 3, characterized in that, the preparation method of the compound shown in Formula II comprises the following steps: 1) In a super-dry organic solvent, in the presence of an inorganic base and 1,2-dibromomethane, the compound shown in Formula III and the compound shown in Formula IV react to obtain the compound shown in Formula V; 2) In a super-dry organic solvent, in the presence of an organic base, the compound shown in Formula V reacts with iodomethane to generate the compound shown in Formula II. The compound of Formula III is preferably one or more of 2,5-di-tert-butylphenol, 2,5-dimethoxyphenol, 2-methyl-5-tert-butylphenol, 2-tert-butyl-5-methoxyphenol; The compound of Formula IV is preferably one or more of 2,5-di-tert-butylaniline, 2,5-dimethoxyaniline, 2-methyl-5-tert-butylaniline, 2-tert-butyl-5-methoxyaniline.

7. The method according to claim 6, characterized in that, in the step 1), the molar ratio of the compound of Formula III, the compound of Formula IV, the inorganic base, and 1,2-dibromomethane is 1:1:(2 - 5):(0.4 - 0.6); in the step 2), the molar ratio of the compound of Formula V, the organic base, and iodomethane is 1:(1.5 - 3):(1 - 1.5).

8. A method for olefin polymerization, characterized in that, using the metal complex according to claim 1 or 2 or the metal complex prepared by the method according to any one of claims 3 - 7 as a catalyst; preferably, the olefin is ethylene and α-olefin.

9. The method according to claim 8, characterized in that, the metal complex is used as the main catalyst and co-catalyzes the olefin polymerization reaction with a co-catalyst; The cocatalyst is one or more of methylaluminoxane, ethylaluminoxane, butylaluminoxane, methylethylaluminoxane and borate compounds; preferably methylaluminoxane.

10. According to the method described in claim 9, it is characterized in that in the cocatalyst, the molar ratio of aluminum metal to the central metal M of the metal complex, Al / M, is 4 to 300, preferably 50 to 150.

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