A catalyst system for the polymerization of olefins and its use

Abstract

This application relates to a catalyst system for olefin polymerization and its application, said catalyst system comprising a mixture of a metal complex catalyst A, a metal complex catalyst B, and a co-catalyst. This catalyst system can catalyze the polymerization of olefin monomers in organic solvents at relatively high temperatures, resulting in polymers with high tensile strength and elongation at break.

Description

Technical Field

[0001] This application relates to the field of olefin polymerization, and more specifically to a catalyst system for olefin polymerization and its application. Existing technology

[0002] Polyolefins are the most produced and widely used polymeric materials among synthetic resins. They possess advantages such as high cost-effectiveness, good mechanical properties, excellent processability, chemical stability, good electrical insulation properties, and recyclability, and are widely used in various fields of agriculture, industry, medical and health care, and daily life. Ethylene is the simplest and cheapest olefin monomer. Synthesizing polyolefin products with different structures and properties from ethylene or using ethylene as the main monomer is one of the hot topics in polymer synthesis research.

[0003] In 1995, Brookhart et al. discovered that the α-diimine palladium and nickel catalyst of formula (1) could catalyze the homopolymerization of ethylene to obtain hyperbranched polyethylene with a rich branched structure (J.Am.Chem.Soc.,1995,117(23):6414-6415).

[0004]

[0005] In 1998, Grubbs et al. discovered that the salicylaldehyde imine-type nickel catalyst of formula (2) could also catalyze the homopolymerization of ethylene to obtain branched polyethylene (Organometallics.1998,17:3149-3151).

[0006]

[0007] This type of polyethylene possesses good solubility, low solution and melt viscosity, and good toughness, making it suitable for use as a rubber material or polyolefin elastomer. It shows promising application prospects in automotive parts, sealing rings, and photovoltaic films. However, this type of polyethylene also faces significant bottlenecks, such as extremely low crystallinity, resulting in amorphous polyethylene that is difficult to process and mold, and insufficient product strength, hindering its widespread application. To address these issues, researchers have designed special catalyst structures to increase the polymer's molecular weight and reduce its branching degree to improve its strength. However, this method inevitably weakens the original good toughness and elasticity of hyperbranched polyethylene.

[0008] Chinese patent CN110590980A designed and synthesized an α-diimine nickel catalyst with a large sterically hindered framework, which changed the electron and spatial effects around the metal center of the catalyst, thereby achieving the goal of obtaining high molecular weight polymers with low branching degree at high temperature. However, the ligand structure of this catalyst is relatively complex, the synthesis process is cumbersome, and the preparation cost is high, which is not conducive to the realization of industrial application. Summary of the Invention

[0009] The purpose of this application is to provide a catalyst system for olefin polymerization and a method for catalyzing olefin polymerization using the same. The catalyst system can maintain high ethylene polymerization activity at higher temperatures and achieve a balance between rigidity and toughness in the polyethylene obtained by polymerization, thereby solving the problems of difficult processing and molding and low strength caused by excessively low crystallinity of hyperbranched polyethylene.

[0010] To achieve the above objectives, this application provides a catalyst system (also referred to herein as a catalyst composition) for olefin polymerization, comprising a mixture of the following components:

[0011] (1) Catalyst A, selected from at least one metal complex of general formula (I) or general formula (II):

[0012]

[0013] In formula (I), R' is a C1-C8 straight-chain or branched alkylene, a C13-C21 diarylalkylene, a C2-C8 dialkylsilylene, or a C12-C20 diarylsilylene; and Each X independently represents an unsubstituted or substituted cyclopentadienyl, fluorenyl, or indenyl group; M is a Group IVB metal; each X is independently selected from halogens, C1-C6 alkyl groups, or C2-C6 alkenyl groups.

[0014]

[0015] In formula (II), and Each of them independently represents cyclopentadienyl, fluorenyl, or indene; R” and R”’ are each independently selected from hydrogen, C1-C8 straight-chain or branched alkyl; M is a Group IVB metal; each X is independently selected from halogen, C1-C6 alkyl, or C2-C6 alkenyl.

[0016] (2) Catalyst B, selected from at least one metal complex of general formula (IIIa) or (IIIb):

[0017]

[0018] In formulas (IIIa) and (IIIb), R1 and R2 are independently hydrogen, C1-C4 alkyl, C1-C4 haloalkyl, halogen, or C1-C4 alkoxy; R3, R4, R6, and R7 are independently C1-C6 alkyl, C3-C6 cycloalkyl, unsubstituted or substituted phenyl, or phenyl-substituted C1-C4 alkyl; R5 and R8 are independently hydrogen, C1-C6 alkyl, C3-C6 cycloalkyl, unsubstituted or substituted phenyl, phenyl-substituted C1-C4 alkyl, halogen, or C1-C4 alkoxy; M is nickel or palladium; X is a halogen, wherein the substituted phenyl has 1-5 substituents selected from the group consisting of halogen, C1-C4 alkyl, and C1-C4 haloalkyl, and

[0019] (3) The co-catalyst is selected from one or more of alkylaluminum, alkylaluminoxane and haloalkylaluminum.

[0020] On the other hand, this application provides a method for olefin polymerization, comprising contacting ethylene monomer and optionally C3-C10 α-olefin in an organic solvent with the catalyst system of this application to carry out a polymerization reaction.

[0021] The catalyst system provided in this application can catalyze the polymerization of ethylene monomers in organic solvents at relatively high temperatures (≥60℃). Compared with existing technologies, the polymer prepared in this application exhibits higher tensile strength while maintaining a high elongation at break, achieving a balance between strength and toughness. Moreover, the olefin polymerization method provided in this application is simple and easy to operate, requiring no complex catalyst structure or harsh reaction conditions, and is easily scalable for industrial production. Detailed Implementation

[0022] The specific embodiments of this application are described in detail below. However, it should be noted that the scope of protection of this application is not limited by these specific embodiments, but is determined by the claims in the appendix.

[0023] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0024] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0025] In the context of this application, unless otherwise expressly defined or the meaning is beyond the understanding of those skilled in the art, hydrocarbon or hydrocarbon derivative groups having three or more carbon atoms (such as propyl, propoxy, butyl, butane, butene, butenyl, hexane, etc.) have the same meaning when not prefixed with "n-" as when prefixed with "n-". For example, propyl is generally understood as n-propyl, and butyl is generally understood as n-butyl, unless otherwise expressly defined.

[0026] In the context of this application, the term "mixed product" refers to the product obtained after the components of a catalyst system are contacted and mixed. Depending on the physicochemical properties and interactions of the components, the product may comprise a physical mixture of the components and / or chemical reaction products.

[0027] In this application, except where expressly stated, any matters or issues not mentioned are directly applicable to aspects known in the art without any modification. Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or concepts are considered part of the original disclosure or original record of this application, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination manifestly unreasonable.

[0028] All patent and non-patent literature mentioned in this article, including but not limited to textbooks and journal articles, are incorporated in full by way of citation.

[0029] In a first aspect, this application provides a catalyst system for olefin polymerization, the catalyst system comprising a mixture of the following components:

[0030] (1) Catalyst A, selected from at least one metal complex of general formula (I) or general formula (II):

[0031]

[0032] In formula (I), R' is a C1-C8 straight-chain or branched alkylene, C13-C21 diarylalkylene, C2-C8 dialkylsilylene or C12-C20 diarylsilylene, preferably a C1-C4 straight-chain or branched alkylene, C13-C17 diarylalkylene, C2-C4 dialkylsilylene or C12-C16 diarylsilylene, more preferably methylene, ethylene, isopropylene, diphenylmethylene, dimethylsilylene or diphenylsilylene; and Each X independently represents an unsubstituted or substituted cyclopentadienyl, fluorenyl, or indenyl group; M is a Group IVB metal; each X is independently selected from halogens, C1-C6 alkyl groups, or C2-C6 alkenyl groups.

[0033]

[0034] In formula (II), and Each of them independently represents cyclopentadienyl, fluorenyl or indene; R” and R”' are each independently selected from hydrogen, C1-C8 straight-chain or branched alkyl, preferably hydrogen, C1-C4 straight-chain or branched alkyl; M is a group IVB metal; each X is independently selected from halogen, C1-C6 alkyl or C2-C6 alkenyl.

[0035] (2) Catalyst B, selected from at least one metal complex of general formula (IIIa) or (IIIb):

[0036]

[0037] In formulas (IIIa) and (IIIb), R1 and R2 are independently hydrogen, C1-C4 alkyl, C1-C4 haloalkyl, halogen, or C1-C4 alkoxy; R3, R4, R6, and R7 are independently C1-C6 alkyl, C3-C6 cycloalkyl, unsubstituted or substituted phenyl, or phenyl-substituted C1-C4 alkyl; R5 and R8 are independently hydrogen, C1-C6 alkyl, C3-C6 cycloalkyl, unsubstituted or substituted phenyl, phenyl-substituted C1-C4 alkyl, halogen, or C1-C4 alkoxy; M is nickel or palladium; X is a halogen, wherein the substituted phenyl has 1-5 substituents selected from the group consisting of halogen, C1-C4 alkyl, and C1-C4 haloalkyl, and

[0038] (3) The co-catalyst is selected from one or more of alkylaluminum, alkylaluminoxane and haloalkylaluminum.

[0039] In a preferred embodiment, in formulas (I) and (II), M is titanium, zirconium, or hafnium, and X is a halogen.

[0040] In the catalyst system of this application, the catalyst B can be exemplified by the following metal complexes:

[0041]

[0042] It should be noted that these metal complexes can be used alone or mixed in any proportion.

[0043] In the catalyst system of this application, the general structural formula of the alkylaluminum used as a co-catalyst can be shown in the following formula (IVa).

[0044] Al(R)3 (IVa)

[0045] In this embodiment, each group R is independently selected from C1-C8 alkyl groups, preferably from methyl, ethyl, propyl, butyl, and isobutyl, and most preferably from ethyl and isobutyl. Furthermore, the alkylaluminum can be used alone or in combination in any proportion.

[0046] Specifically, examples of alkylaluminum include trimethylaluminum (Al(CH3)3), triethylaluminum (Al(CH3CH2)3), tri-n-propylaluminum (Al(n-C3H7)3), triisopropylaluminum (Al(i-C3H7)3), triisobutylaluminum (Al(i-C4H9)3), and tri-n-pentylaluminum (Al(n-C5H7)3). 11 )3) Tri-n-hexyl aluminum (Al(n-C6H) 13 3) Diethylmethylaluminum (Al(CH3)(CH3CH2)2) and dimethylethylaluminum (Al(CH3)2(CH3CH2)), etc., wherein trimethylaluminum, triethylaluminum and triisobutylaluminum are preferred.

[0047] In the catalyst system of this application, the general structural formula of the alkylaluminoxane used as a co-catalyst can be shown as (IVb) or (IVc) below.

[0048]

[0049] In this embodiment, each group R is independently selected from C1-C8 alkyl groups, preferably from methyl, ethyl, propyl, butyl, and isobutyl groups, and most preferably from methyl and ethyl groups. n is any integer in the range of 1-50, preferably any integer in the range of 10-30. Furthermore, the alkylaluminoxane can be used alone or in combination in any proportion.

[0050] Specifically, the alkylaluminoxane is preferably selected from methylaluminoxane, ethylaluminoxane, isobutylaluminoxane, n-butylaluminoxane, modified methylaluminoxane, and modified ethylaluminoxane, and more preferably from methylaluminoxane and modified methylaluminoxane.

[0051] In the catalyst system of this application, the general structural formula of the haloalkylaluminum used as a co-catalyst can be shown in the following formula (IVd).

[0052] Al(R) n X 3-n (IVd)

[0053] In this embodiment, each R group is independently selected from C1-C8 alkyl groups, preferably from methyl, ethyl, propyl, butyl, and isobutyl, and most preferably from ethyl and isobutyl; X is a halogen, preferably chlorine or bromine; and n is 1 or 2. Furthermore, the aluminum haloalkyl can be used alone or in any combination of multiple groups in any proportion.

[0054] Specifically, examples of the aforementioned alkyl halogenated aluminum include, for instance, dichlorodimethylaluminum (Al(CH3)2Cl), dichloromethylaluminum (Al(CH3)Cl2), dichlorodiethylaluminum (Al(CH3CH2)2Cl), dichloroethylaluminum (Al(CH3CH2)Cl2), dichlorodipropylaluminum (Al(C3H7)2Cl), dichloropropylaluminum (Al(C3H7)Cl2), dichlorodi-n-butylaluminum (Al(n-C4H9)2Cl), dichlorodi-n-butylaluminum (Al(n-C4H9)Cl2), dichlorodiisobutylaluminum (Al(i-C4H9)2Cl), dichloroisobutylaluminum (Al(i-C4H9)Cl2), and dichlorodi-n-pentylaluminum (Al(n-C5H9)Cl2). 11 )2Cl), dichloro-n-pentyl aluminum (Al(n-C5H) 11 Cl2), diisopentylaluminum chloride (Al(i-C5H) 11 )2Cl), dichloroisopentylaluminum (Al(i-C5H) 11 Cl2), di-n-hexyl aluminum chloride (Al(n-C6H) 13 )2Cl), dichloro-n-hexylaluminum (Al(n-C6H) 13 Cl2), aluminum monochlorodiisohexyl (Al(i-C6H) 13 )2Cl), dichloroisohexylaluminum (Al(i-C6H) 13 The aluminum alloy is selected from the following: chloromethyl ethyl aluminum (Al(CH3)(CH3CH2)Cl), chloromethyl propyl aluminum (Al(CH3)(C3H7)Cl), chloromethyl n-butyl aluminum (Al(CH3)(n-C4H9)Cl), chloromethyl isobutyl aluminum (Al(CH3)(i-C4H9)Cl), chloroethyl propyl aluminum (Al(CH2CH3)(C3H7)Cl), chloroethyl n-butyl aluminum (Al(CH2CH3)(n-C4H9)Cl), chloroethyl isobutyl aluminum (Al(CH2CH3)(i-C4H9)Cl), etc., preferably from diethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, dibutylaluminum chloride, diisobutylaluminum chloride, diisobutylaluminum chloride, dihexylaluminum chloride, and dihexylaluminum chloride, and more preferably from diethylaluminum chloride and diethylaluminum chloride.

[0055] In a preferred embodiment, in the catalyst system of this application, the molar ratio of catalyst A to catalyst B, based on the central metal atoms, is 1:10 to 10:1, preferably 2:8 to 8:2, and more preferably 4:6 to 6:4.

[0056] In a preferred embodiment, in the catalyst system of this application, the molar ratio of the total amount of the co-catalyst, calculated as aluminum atoms, to the total amount of catalyst A and catalyst B, calculated as central metal atoms, is (10-5000):1, preferably (100-2000):1, and more preferably (500-1000):1.

[0057] In a second aspect, this application also provides a method for olefin polymerization, comprising contacting an ethylene monomer and optionally a C3-C10 α-olefin in an organic solvent with a catalyst system of this application to carry out a polymerization reaction.

[0058] In a preferred embodiment, the C3-C10 α-olefin is selected from propylene, 1-butene, 1-hexene, 1-octene, or a combination thereof.

[0059] In a preferred embodiment, the organic solvent is selected from aromatic hydrocarbons, alkanes, and haloalkanes, preferably from one or more of toluene, dichloromethane, n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, n-octane, and the Isopare series of solvents, and more preferably from one or more of n-hexane, cyclohexane, and toluene.

[0060] In a preferred embodiment, the conditions for the polymerization reaction include: a temperature of 0-150°C, preferably 60-100°C; and a polymerization pressure of 0.1-4.0 MPa, preferably 0.5-3.0 MPa.

[0061] In the olefin polymerization method of this application, there are no particular restrictions on the way catalyst A, catalyst B, and co-catalyst are added to the polymerization reaction system. The co-catalyst can be added first, followed by catalyst A and catalyst B; or catalyst A and catalyst B can be added first, followed by the co-catalyst; or the three can be mixed and introduced together or added separately and simultaneously; or a portion of the co-catalyst can be added first, followed by catalyst A, catalyst B, and the remaining co-catalyst. When catalyst A, catalyst B, and co-catalyst are added separately, they can be added sequentially through the same feeding line or simultaneously or sequentially through multiple feeding lines.

[0062] Furthermore, in the olefin polymerization method of this application, alkylaluminum, alkylaluminoxane, or haloalkylaluminum as cocatalysts are generally used in solution form. There are no particular restrictions on the solvent used when preparing the cocatalyst solution, as long as it can dissolve the cocatalyst. The solvent is generally selected as an alkane solvent, such as n-pentane, isopentane, cyclopentane, neopentane, etc., or an aromatic solvent, such as toluene, ethylbenzene, xylene, etc. According to this application, for ease of subsequent separation, it is preferable to use the same solvent as the polymerization solvent; or the same solvent as one of the solvents in the mixed solvents used for polymerization.

[0063] Example

[0064] The implementation schemes of this application will be described in detail below with reference to the embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate this application and should not be regarded as limiting the scope of this application.

[0065] The following methods were used to determine the molecular weight of the polymers obtained in the examples and comparative examples: The molecular weight of the polymers was determined using a Polymer Laboratories PL-220 gel permeation chromatography system, with 1,2,4-trichlorobenzene as the mobile phase, polystyrene as the standard, a differential detector, a flow rate of 1.0 mL / min, a measurement temperature of 150 °C, and a sample concentration of 2.0 mg / mL. The polymer dispersibility index (PDI) was calculated based on the measured weight-average molecular weight and number-average molecular weight.

[0066] The degree of branching of the polymers obtained in the following examples and comparative examples was calculated based on carbon NMR spectra. Specifically, the microstructure of the polyethylene samples was determined using a Bruker Avance 600M NMR spectrometer. The samples were dissolved in deuterated o-dichlorobenzene to prepare a solution. The test temperature was 120°C, and 1H NMR spectra were obtained after 2000 and 6000 scans respectively. 1 H-NMR and carbon nuclear magnetic resonance (NMR) 13 C-NMR).

[0067] The thermal properties (melting point T) of the polymers obtained in the following examples and comparative examples m The test method for enthalpy of fusion ΔH and crystallinity is as follows: The TA-2000 differential scanning calorimeter (DSC) is used for measurement. Nitrogen atmosphere is used. The temperature is heated from 20℃ to 150℃ at a rate of 20℃ / min, held for 5min to eliminate thermal history, then lowered to -70℃ at a rate of 20℃ / min, held for 5min, and then raised to 150℃ again at a rate of 20℃ / min. The secondary heating curve is recorded.

[0068] The tensile properties (tensile strength and fracture strain) of the polymers obtained in the following examples and comparative examples were tested using the standard GB / T1040-1992. The testing instrument was a universal testing machine - Zwick / Roell-Z020. The specimen type was Type I. The specimens were prepared using a HAAKE MiniJet II micro high-performance composite molding system and a Tensile bar ISO527-5A tensile die (L75mm, W12.5mm, H2mm). The injection temperature was 280-300℃, the die temperature was 80-100℃, the holding pressure was 1150 bar, and the holding time was 15s.

[0069] In the following examples and comparative examples:

[0070] Polymerization activity is calculated using the following formula:

[0071] W = Q / (M × H)

[0072] Where W represents the polymerization activity; Q represents the yield of the obtained polymer (in g); M represents the total molar amount of catalyst A and catalyst B (in mol); and H represents the polymerization time (in h).

[0073] The relative crystallinity X of the polymer is calculated using the following formula:

[0074]

[0075] ΔH f This is the measured enthalpy of fusion of polyethylene; The enthalpy of fusion for 100% crystalline polyethylene is 291.7 J / g.

[0076] Example 1

[0077] In a glove box, catalyst A1 (ethylene bis-1,1-(tetrahydroindenyl)zirconia dichloride) (0.011 mmol), catalyst B1 (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 60 °C, and ethylene at 1.5 MPa was introduced. The polymerization reaction was carried out for 30 min with stirring at 200 rpm. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and then vacuum dried at 60 °C to constant weight. The obtained polymer P1 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0078]

[0079] Example 2

[0080] In a glove box, catalyst A2 (rac-vinylbisindene dizirconia) (0.011 mmol), catalyst B2 (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 60 °C, and ethylene at 2.3 MPa was introduced. The polymerization reaction was carried out for 30 min with stirring at 200 rpm. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and vacuum dried at 60 °C to constant weight. The obtained polymer P2 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0081]

[0082] Example 3

[0083] In a glove box, catalyst A3 (dimethylsilyl-bis-(1-indenyl)zirconium dichloride) (0.011 mmol), catalyst B6 (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 80 °C, and ethylene at 1.5 MPa was introduced. The polymerization reaction was carried out for 30 min with stirring at 200 rpm. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and then vacuum dried at 60 °C to constant weight. The obtained polymer P3 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0084]

[0085] Example 4

[0086] In a glove box, catalyst A2 (rac-vinylbisindenezirconium dichloride) (0.011 mmol), catalyst B2 (0.011 mmol), dichloromethane (10 mL), methylaluminoxane (22 mmol), and dichloroethylaluminum (6.6 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 60 °C, and ethylene at 2.3 MPa was introduced. The polymerization reaction was carried out for 30 min with stirring at 200 rpm. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and vacuum dried at 60 °C to constant weight. The obtained polymer P4 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0087] Example 5

[0088] In a glove box, catalyst A2 (rac-vinylbisindene dizirconia) (0.011 mmol), catalyst B2 (0.011 mmol), dichloromethane (10 mL), and modified methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 60 °C, and ethylene at 2.3 MPa was introduced. The polymerization reaction was carried out under stirring at 200 rpm for 30 min. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and vacuum dried at 60 °C to constant weight. The obtained polymer P5 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0089] Example 6

[0090] In a glove box, catalyst A2 (rac-vinylbisindene dizirconia) (0.0055 mmol), catalyst B2 (0.0165 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 60 °C, and ethylene at 2.3 MPa was introduced. The polymerization reaction was carried out for 30 min with stirring at 200 rpm. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and vacuum dried at 60 °C to constant weight. The obtained polymer P6 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0091] Example 7

[0092] In a glove box, catalyst A2 (rac-vinylbisindene dizirconia) (0.0165 mmol), catalyst B2 (0.0055 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 60 °C, and ethylene at 2.3 MPa was introduced. The polymerization reaction was carried out for 30 min with stirring at 200 rpm. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and then vacuum dried at 60 °C to constant weight. The obtained polymer P7 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0093] Example 8

[0094] In a glove box, catalyst A2 (rac-vinylbisindene dizirconia) (0.011 mmol), catalyst B2 (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (11 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 60 °C, and ethylene at 2.3 MPa was introduced. The polymerization reaction was carried out for 30 min with stirring at 200 rpm. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and vacuum dried at 60 °C to constant weight. The obtained polymer P8 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0095] Example 9

[0096] In a glove box, catalyst A2 (rac-vinylbisindene dizirconia) (0.011 mmol), catalyst B2 (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 80 °C, and ethylene at 2.3 MPa was introduced. The polymerization reaction was carried out under stirring at 200 rpm for 30 min. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and vacuum dried at 60 °C to constant weight. The obtained polymer P9 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0097] Example 10

[0098] In a glove box, catalyst A2 (rac-vinylbisindene dizirconia) (0.011 mmol), catalyst B2 (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. When the reactor reached 100 °C, ethylene was introduced at 2.3 MPa, and the polymerization reaction was carried out under stirring at 200 rpm for 30 min. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and then vacuum dried at 60 °C to constant weight. The obtained polymer P10 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0099] Comparative Example 1

[0100] In a glove box, catalyst A2 (rac-vinylbisindene dizirconia) (0.022 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to 100 mL Erlenmeyer flasks and mixed for later use. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 100 °C, and ethylene at 2.3 MPa was introduced. The polymerization reaction was carried out for 30 min with stirring at 200 rpm. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and then vacuum dried at 60 °C to constant weight. The obtained polymer P11 was weighed. The polymerization activity and polymer test results of this comparative example are shown in Table 1.

[0101] Comparative Example 2

[0102] In a glove box, catalyst B2 (0.022 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to 100 mL Erlenmeyer flasks and mixed for later use. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 60 °C, and ethylene at 2.3 MPa was introduced. The polymerization reaction was carried out for 30 min with stirring at 200 rpm. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and then vacuum dried at 60 °C to constant weight. The obtained polymer P12 was weighed. The polymerization activity and polymer test results of this comparative example are shown in Table 1.

[0103] Comparative Example 3

[0104] In a glove box, metallocene catalyst (dibutylsilyl-bis-(1-indenyl)zirconia dichloride) (0.011 mmol), nickel metal catalyst B' (0.011 mmol) as shown in Formula V, dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to 100 mL Erlenmeyer flasks and mixed for later use. A 2 L high-pressure polymerization reactor was purged with high-purity nitrogen at 100 °C for 2 hours. Hexane (1 L) and the prepared catalyst solution were then added sequentially. The reactor was heated to 60 °C, and ethylene at 1.5 MPa was introduced. The polymerization reaction was carried out under stirring at 200 rpm for 30 min. After the reaction, the polymerization solution was poured into an acidified ethanol solution to precipitate solid polymer. The polymer was filtered, washed, and vacuum dried at 60 °C to constant weight. The obtained polymer P13 was weighed. The polymerization activity and polymer test results of this comparative example are shown in Table 1.

[0105]

[0106] Table 1. Polymerization test results for each example and comparative example.

[0107]

[0108] As can be seen from the comparison between the above embodiments and comparative examples, by using the catalyst system provided in this application, the molecular weight distribution of the obtained polymer is broadened, and it has a certain degree of crystallinity. While maintaining a high fracture strain rate, it has higher tensile strength, thereby achieving a balance between strength and toughness and giving polyethylene materials a wider range of applications.

[0109] As can be seen from the comparison between the examples and Comparative Example 3, compared with the existing catalyst system, the catalyst system provided in this application has higher polymerization activity (greater than 2 times) at a higher polymerization temperature (60°C), and the resulting polyethylene has higher branching degree, lower crystallinity, greater fracture strain, and better performance in terms of toughness.

[0110] While the specific embodiments of this application have been described in detail above, it should be noted that the scope of protection of this application is not limited to these specific embodiments, but is determined by the appended claims. Those skilled in the art can make appropriate modifications to these embodiments without departing from the technical concept and spirit of this application, and these modified embodiments are obviously also included within the scope of protection of this application.

Claims

1. A catalyst system for olefin polymerization, comprising a mixture of the following components: (1) Catalyst A, selected from at least one metal complex of general formula (I) or general formula (II): In formula (I), R' is a C1-C8 straight-chain or branched alkylene, a C13-C21 diarylalkylene, a C2-C8 dialkylsilylene, or a C12-C20 diarylsilylene; and Each X independently represents an unsubstituted or substituted cyclopentadienyl, fluorenyl, or indenyl group; M is a Group IVB metal; each X is independently selected from halogens, C1-C6 alkyl groups, or C2-C6 alkenyl groups. In formula (II), and Each of them independently represents cyclopentadienyl, fluorenyl, or indene; R” and R”’ are each independently selected from hydrogen, C1-C8 straight-chain or branched alkyl; M is a Group IVB metal; each X is independently selected from halogen, C1-C6 alkyl, or C2-C6 alkenyl. (2) Catalyst B, selected from at least one metal complex of general formula (IIIa) or (IIIb): In formulas (IIIa) and (IIIb), R1 and R2 are independently hydrogen, C1-C4 alkyl, C1-C4 haloalkyl, halogen, or C1-C4 alkoxy; R3, R4, R6, and R7 are independently C1-C6 alkyl, C3-C6 cycloalkyl, unsubstituted or substituted phenyl, or phenyl-substituted C1-C4 alkyl; R5 and R8 are independently hydrogen, C1-C6 alkyl, C3-C6 cycloalkyl, unsubstituted or substituted phenyl, phenyl-substituted C1-C4 alkyl, halogen, or C1-C4 alkoxy; M is nickel; X is a halogen, wherein the substituted phenyl has 1-5 substituents selected from the group consisting of halogen, C1-C4 alkyl, and C1-C4 haloalkyl, and (3) A co-catalyst, selected from one or more of alkylaluminum, alkylaluminoxane and haloalkylaluminum. in, The molar ratio of catalyst A to catalyst B, based on the central metal atoms, is 1:10 to 10:

1.

2. The catalyst system according to claim 1, wherein, In formula (I), R' is a C1-C4 straight-chain or branched alkylene, a C13-C17 diarylalkylene, a C2-C4 dialkylsilylene, or a C12-C16 diarylsilylene.

3. The catalyst system according to claim 2, wherein, In formula (I), R' is methylene, ethylene, isopropylene, diphenylmethylene, dimethylmethylenesilyl or diphenylmethylenesilyl.

4. The catalyst system according to claim 1, wherein, In formula (II), R” and R”' are each independently selected from hydrogen, C1-C4 straight-chain or branched alkyl groups.

5. The catalyst system according to claim 1, wherein, In formulas (I) and (II), M is titanium, zirconium or hafnium, and X is a halogen.

6. The catalyst system according to claim 1, wherein, The catalyst B is selected from at least one of the following metal complexes:

7. The catalyst system according to any one of claims 1-6, wherein: The general structural formula of the co-catalyst alkylaluminum is shown in formula (IVa). Al(R)3(IVa) In this context, each R group is independently selected from C1-C8 alkyl groups; The general structural formula of the cocatalyst alkylaluminoxane is shown in formula (IVb) or (IVc). In this context, each group R is independently selected from C1-C8 alkyl groups, and n is any integer in the range of 1-50; The general structural formula of the cocatalyst, haloalkylaluminum, is shown in formula (IVd). Al(R) n X 3-n (IVd) In this context, each R group is independently selected from C1-C8 alkyl groups, X is a halogen, and n is 1 or 2.

8. The catalyst system according to claim 7, wherein, In formula (IVa), each group R is independently selected from methyl, ethyl, propyl or butyl.

9. The catalyst system according to claim 8, wherein, In formula (IVa), each group R is independently selected from ethyl or isobutyl.

10. The catalyst system according to claim 7, wherein, In formula (IVb) or (IVc), each group R is independently selected from methyl, ethyl, propyl or butyl.

11. The catalyst system according to claim 10, wherein, In formula (IVb) or (IVc), each group R is independently selected from methyl, ethyl or isobutyl.

12. The catalyst system according to claim 7, wherein, In equation (IVb) or (IVc), n is any integer in the range of 10-30.

13. The catalyst system according to claim 7, wherein, In formula (IVd), each group R is independently selected from methyl, ethyl, propyl or butyl.

14. The catalyst system according to claim 13, wherein, In formula (IVd), each group R is independently selected from ethyl or isobutyl.

15. The catalyst system according to claim 7, wherein, In formula (IVd), X is chlorine or bromine.

16. The catalyst system according to any one of claims 1-6, wherein, The molar ratio of catalyst A to catalyst B, based on the central metal atoms, is 2:8 to 8:

2.

17. The catalyst system according to claim 16, wherein, The molar ratio of catalyst A to catalyst B, based on the central metal atoms, is 4:6 to 6:

4.

18. The catalyst system according to any one of claims 1-6, wherein, The molar ratio of the total amount of the co-catalyst, calculated in terms of aluminum atoms, to the total amount of catalyst A and catalyst B, calculated in terms of central metal atoms, is (10-5000):

1.

19. The catalyst system according to claim 18, wherein, The molar ratio of the total amount of the co-catalyst, calculated in terms of aluminum atoms, to the total amount of catalyst A and catalyst B, calculated in terms of central metal atoms, is (100-2000):

1.

20. The catalyst system according to claim 19, wherein, The molar ratio of the total amount of the co-catalyst, calculated in terms of aluminum atoms, to the total amount of catalyst A and catalyst B, calculated in terms of central metal atoms, is (500-1000):

1.

21. A method for olefin polymerization, comprising contacting an ethylene monomer and optionally a C3-C10 α-olefin in an organic solvent with a catalyst system according to any one of claims 1-20 to carry out a polymerization reaction.

22. The method of claim 21, wherein the organic solvent is selected from aromatic hydrocarbons, alkanes, and haloalkanes.

23. The method according to claim 22, wherein the organic solvent is selected from one or more of toluene, dichloromethane, n-pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, n-octane, and the Isopare series of solvents.

24. The method of claim 23, wherein the organic solvent is selected from one or more of n-hexane, cyclohexane, and toluene.

25. The method according to any one of claims 21-24, wherein the conditions for the polymerization reaction include: Temperature range: 0-150℃; The polymerization pressure is 0.1-4.0 MPa.

26. The method according to claim 25, wherein the polymerization reaction is carried out at a temperature of 60-100°C.

27. The method according to claim 25, wherein the pressure of the polymerization reaction is 0.5-3.0 MPa.

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