A block polyethylene and a method for its preparation

Abstract

The application relates to a block polyethylene and a preparation method thereof, the preparation method comprising the following steps: using ethylene as the only polymerization monomer to perform ethylene solution polymerization in a reaction system added with an alpha-diimine nickel metal complex, a metallocene complex, a cocatalyst, an alkyl zinc chain shuttling agent and an organic solvent. The preparation method is simple and easy to operate, industrial production can be easily realized, and the obtained block polyethylene has more excellent mechanical properties and processing performance.

Description

Technical Field

[0001] This application relates to the field of olefin polymerization, specifically to a block polyethylene and its preparation method. Existing technology

[0002] Polyolefin materials are widely used in various aspects of daily life due to their excellent mechanical properties, processing performance, strong chemical corrosion resistance, and good electrical insulation properties. They are found in industrial packaging materials, agricultural films, medical and health packaging materials, food packaging materials, and urban pipelines. Polyolefins have become the most produced and widely used polymer material among the world's three major synthetic resins. Ethylene, as the simplest, cheapest, and most readily available olefin monomer, is of great significance if polyethylene materials with different application properties can be prepared solely from ethylene monomers. This is also one of the hot research topics in academia and industry.

[0003] The homopolymerization of ethylene using metallocene catalysts typically yields linear polyethylene, which possesses high crystallinity, high melting point, and high tensile strength, but exhibits relatively poor toughness. To improve the toughness of polyethylene materials, it is generally prepared by copolymerizing ethylene with other α-olefin monomers, such as propylene, 1-butene, 1-hexene, and 1-octene, to produce linear low-density polyethylene with certain branches. Brookhart and Grubbs et al. discovered that homopolymerization of ethylene using post-transition metal (nickel or palladium) catalysts can yield hyperbranched polyethylene with a rich branched structure (J. Am. Chem. Soc., 1995, 117(23): 6414-6415; Organometallics. 1998, 17: 3149-3151). Hyperbranched polyethylene has good solubility, low solution and melt viscosity, and good toughness, and can be used as a toughening modifier for plastics, blended with high-density polyethylene or polypropylene to improve their toughness. However, in practical applications, problems such as difficulty in achieving uniform blending and poor compatibility have been found, which adversely affect the use of the material. As is well known in the art, block polymers possess superior mechanical and processing properties compared to physical blends. Block polymer molecules contain both "soft segments" formed from branched polyethylene and "hard segments" formed from linear polyethylene, and can be considered blends at the molecular level, effectively addressing the issue of blend uniformity.

[0004] Existing methods for preparing block polyethylene typically involve block copolymerization of ethylene and α-olefins. Dow Chemical Company, using a novel combination of non-metallocene catalysts, invented a new chain-shutling polymerization technology for olefins and introduced a novel polyolefin thermoplastic elastomer—ethylene-octene block copolymer (OBC). OBC is composed of alternating segments of crystallizable polyethylene with extremely low comonomer content and high melting points, and amorphous polyethylene soft segments with high comonomer content and low glass transition temperatures. Compared to POE, OBC has a higher crystallization temperature and melting point, a more regular crystalline morphology, and a lower glass transition temperature, exhibiting superior performance in tensile strength, elongation at break, and elastic recovery (Science, 2006, 312:714-719). However, the high production cost due to the use of expensive 1-octene monomers hinders its widespread adoption and practical application. Summary of the Invention

[0005] The purpose of this application is to provide a block polyethylene and its preparation method. The block polyethylene forms a blend of crystalline polyethylene segments and amorphous polyethylene segments at the molecular level, which effectively overcomes the problems of uneven mixing and poor compatibility of intermolecular blends, and has better processing performance and mechanical properties.

[0006] To achieve the above objectives, this application provides a method for preparing block polyethylene, comprising the step of using ethylene as the sole monomer to perform ethylene solution polymerization in a reaction system containing an α-diimine nickel metal complex, a metallocene complex, a co-catalyst, an alkyl zinc chain shuttle, and an organic solvent, wherein the co-catalyst is selected from at least one of alkylaluminum, alkylaluminoxane, haloalkylaluminum, arylborane, and arylborates.

[0007] On the other hand, this application provides a block polyethylene with a weight-average molecular weight of 5-1,000,000 g / mol, a polymer dispersibility index (PDI) of 1.5-4.0, a branching degree of 20-75 / 1000C, and a crystallinity of 5-35%.

[0008] Preferably, the block polyethylene is prepared by the block polyethylene preparation method of this application.

[0009] Compared with existing technologies, the preparation method of this application uses only ethylene as the sole polymerizing monomer, eliminating the need for expensive α-olefins as comonomers. This yields block polyethylene with both "soft segments" formed by branched polyethylene and "hard segments" formed by linear polyethylene, creating a molecular-level blend. This effectively solves the problems of difficult uniform mixing and poor compatibility in intermolecular blends in existing technologies. Furthermore, the provided block polyethylene exhibits superior processing and mechanical properties compared to physical blends. In the method of this application, both the α-diimine nickel metal complex and the metallocene complex possess high high-temperature thermal stability. Therefore, the provided composite catalyst can catalyze the polymerization of ethylene in organic solvents at relatively high temperatures (≥60℃), exhibiting high polymerization activity (greater than 10). 6 The method of this application has the advantages of easy molecular weight control (gPE / (molcat·h)), and is simple and easy to operate, requiring no harsh reaction conditions, making it easy to achieve industrial production. Detailed Implementation

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] As described above, in a first aspect, this application provides a method for preparing block polyethylene, comprising the step of performing ethylene solution polymerization using ethylene as the sole polymerization monomer in a reaction system containing an α-diimine nickel metal complex, a metallocene complex, a co-catalyst, an alkyl zinc chain shuttle, and an organic solvent, wherein the co-catalyst is selected from at least one of alkylaluminum, alkylaluminoxane, haloalkylaluminum, arylborane, and arylborates.

[0017] In a preferred embodiment, the α-diimine nickel metal complex (also referred to herein as catalyst A) is selected from one or more metal complexes of general formula (Ia) or (Ib):

[0018]

[0019] In formulas (Ia) and (Ib), R1 and R2 are independently hydrogen, C1-C4 alkyl, C1-C4 haloalkyl, halogen, or C1-C4 alkoxy; n is an integer from 0 to 4; R3, R4, R6, and R7 are independently C1-C6 chain alkyl, C3-C6 cycloalkyl, unsubstituted or substituted phenyl, or phenyl-substituted C1-C4 alkyl; R5 and R8 are independently hydrogen, C1-C6 chain alkyl, C3-C6 cycloalkyl, unsubstituted or substituted phenyl, phenyl-substituted C1-C4 alkyl, halogen, or C1-C4 alkoxy; each X is independently selected from halogen, C1-C6 alkyl, or C2-C6 alkenyl, wherein the substituted phenyl has 1 to 5 substituents selected from the group consisting of halogen, C1-C4 alkyl, and C1-C4 haloalkyl.

[0020] In a further preferred embodiment, the catalyst A can be exemplified by the following metal complexes:

[0021]

[0022]

[0023] It should be noted that these metal complexes can be used individually or mixed in any proportion.

[0024] In a further preferred embodiment, the α-diimine nickel metal complex (catalyst A) is selected from one or more complexes having the following chemical structural formulas:

[0025]

[0026] In a preferred embodiment, the metallocene complex (also referred to herein as catalyst B) is selected from one or more metal complexes of general formula (II).

[0027]

[0028] In formula (II), R' is a C1-C8 straight-chain or branched alkylene, a C13-C21 diarylalkylene, a C2-C8 dialkylsilylene, or a C12-C20 diarylsilylene, preferably a C1-C4 straight-chain or branched alkylene, a C13-C17 diarylalkylene, a C2-C4 dialkylsilylene, or a C12-C16 diarylsilylene, more preferably methylene, ethylene, isopropylene, diphenylmethylene, dimethylsilylene, or diphenylsilylene; and Each of the elements independently represents an unsubstituted or substituted cyclopentadienyl, fluorenyl, or indene; M is a Group IVB metal, preferably titanium or zirconium; each of the elements X is independently selected from halogens, C1-C6 alkyl groups, or C2-C6 alkenyl groups.

[0029] In a preferred embodiment, the molar ratio (based on the number of central metal atoms) of catalyst A to catalyst B added to the reaction system is 1:10 to 10:1, preferably 2:8 to 8:2, and more preferably 4:6 to 6:4.

[0030] In a preferred embodiment, the alkylaluminum used as a co-catalyst has the general structural formula shown in formula (IIIa).

[0031] Al(R)3 (IIHa)

[0032] In this embodiment, each group R is independently selected from C1-C8 alkyl groups, preferably from methyl, ethyl, propyl, butyl, and isobutyl, and more preferably from ethyl and isobutyl. Furthermore, the alkylaluminum can be used alone or in any combination of multiple groups in any proportion.

[0033] 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.

[0034] In a preferred embodiment, the alkylaluminoxane used as a cocatalyst has the general structural formula shown in formula (IIIb) or (IIIc).

[0035]

[0036] In this embodiment, each group R is independently selected from C1-C8 alkyl groups, preferably from methyl, ethyl, propyl, butyl, and isobutyl, more preferably from methyl and ethyl, and 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.

[0037] 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.

[0038] In a preferred embodiment, the general structural formula of the haloalkylaluminum used as a cocatalyst is shown in formula (IIId).

[0039] Al(R) n X 3-n (IIId)

[0040] In this embodiment, each group R is independently selected from C1-C8 alkyl groups, preferably methyl, ethyl, propyl, butyl, and isobutyl, more preferably 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.

[0041] 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.

[0042] In a preferred embodiment, the arylborane and arylborate used as co-catalysts are selected from triphenylborane, tris(pentafluorophenyl)borane, triphenylcarbazone(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate, triethylammonium tetra(pentafluorophenyl)borate, 1-butyl-3-methylimidazolium tetrafluoroborate, ferrocene tetrafluoroborate, trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, triisopropylammonium tetraphenylborate, tri-n-butylammonium tetraphenylborate, trimethylammonium tetra(4-methylphenyl)borate, and triisopropylammonium tetra(4-methylphenyl)borate. One or more of the following: trimethylammonium tetra(2,4-dimethylphenyl)borate, triethylammonium tetra(2,4-dimethylphenyl)borate, trimethylammonium tetra(4-trifluoromethylphenyl)borate, tri-n-butylammonium tetra(4-trifluoromethylphenyl)borate, tri-n-butylammonium tetra(pentafluorophenyl)borate, and N,N-diethylphenylammonium tetra(pentafluorophenyl)borate, more preferably selected from one or more of tri(pentafluorophenyl)boron, triphenylcarbon tetra(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate, and triethylammonium tetra(pentafluorophenyl)borate.

[0043] In a preferred embodiment, the molar ratio of the total amount (based on aluminum atoms) of the co-catalysts alkylaluminum, alkylaluminoxane, and haloalkylaluminum added to the reaction system to the total amount (based on central metal atoms) of catalyst A and catalyst B is (10-5000):1, preferably (100-2000):1, more preferably (500-1000):1; and / or the molar ratio of the total amount (based on boron atoms) of the co-catalysts arylborane and arylbordate added to the reaction system to the total amount (based on central metal atoms) of catalyst A and catalyst B is (1-10):1, preferably (2-5):1.

[0044] In a preferred embodiment, the alkyl zinc chain shuttle is selected from at least one organozinc compound as shown in general formula (IV).

[0045] Zn(R)2(IV)

[0046] Each of the groups R is independently selected from C1-C10 straight-chain or branched alkyl groups, preferably selected from at least one of methyl, ethyl, isopropyl, n-butyl, isobutyl and n-hexyl, and more preferably selected from at least one of methyl and ethyl.

[0047] In a preferred embodiment, the molar ratio of the amount of alkyl zinc chain shuttle agent added to the reaction system (based on zinc atoms) to the total amount of catalyst A and catalyst B (based on central metal atoms) is (1-1000):1, preferably (50-600):1, and more preferably (100-500):1.

[0048] 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-pentane, n-hexane, cyclohexane, toluene, and dichloromethane.

[0049] In a preferred embodiment, the polymerization reaction conditions 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.

[0050] In the method of this application, there is no particular limitation on the way catalyst A, catalyst B, co-catalyst, and chain shuttle are added to the polymerization reaction system. It can be that the co-catalyst is added first, followed by catalysts A, B, and the chain shuttle; or the co-catalyst and the chain shuttle are added first, followed by catalysts A and B; or all four are first mixed and then added together; or they are added separately and simultaneously; or a portion of the co-catalyst is added first, followed by catalysts A, B, the chain shuttle, and the remaining co-catalyst. When catalysts A, B, the chain shuttle, and the co-catalyst are added separately, they can be added sequentially through the same feeding line, sequentially through multiple feeding lines, or simultaneously through multiple feeding lines.

[0051] Furthermore, in the method of this application, the cocatalysts alkylaluminum, aluminoxane, and haloalkylaluminum are generally used in solution form. There are no particular limitations on the solvent used in 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.

[0052] In a second aspect, this application provides a block polyethylene with a weight-average molecular weight of 5-1,000,000 g / mol, a polymer dispersibility index (PDI) of 1.5-4.0, a branching degree of 20-75 / 1000C, and a crystallinity of 5-35%.

[0053] In a preferred embodiment, the block polyethylene has a weight-average molecular weight of 100,000-400,000 g / mol, a polymer dispersibility index (PDI) of 1.6-3.5, a branching degree of 30-75 / 1000C, and a crystallinity of 5-30%.

[0054] In a further preferred embodiment, the block polyethylene has a weight-average molecular weight of 150,000-350,000 g / mol, a polymer dispersibility index (PDI) of 1.8-3.2, a branching degree of 45-72 / 1000C, and a crystallinity of 7-20%.

[0055] In a preferred embodiment, the melting point T of the block polyethylene is... m The temperature is 40-100℃, preferably 45-95℃, more preferably 45-90℃, and the enthalpy of melting ΔH is 10-70J / g, preferably 15-65J / g, more preferably 15-60J / g.

[0056] In a preferred embodiment, the block polyethylene is prepared by the block polyethylene preparation method of this application.

[0057] Example

[0058] 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.

[0059] 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.

[0060] 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).

[0061] The thermal properties (melting point T) of the polymers obtained in the following examples and comparative examples mThe 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.

[0062] 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.

[0063] In the following examples and comparative examples:

[0064] Polymerization activity is calculated using the following formula:

[0065] W = Q / (M × H)

[0066] Where W represents 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 polymerization time (in h).

[0067] The relative crystallinity X of the polymer is calculated using the following formula:

[0068]

[0069] ΔH f This is the measured enthalpy of fusion of polyethylene; The enthalpy of fusion for 100% crystalline polyethylene is 291.7 J / g.

[0070] Example 1

[0071] In a glove box, catalyst A2 (0.011 mmol), catalyst B1 (ethylene bis-1,1-(tetrahydroindenyl)zirconia dichloride) (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to 100 mL Erlenmeyer flasks and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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.

[0072]

[0073] Example 2

[0074] In a glove box, catalyst A2 (0.011 mmol), catalyst B2 (rac-vinylbisindene dizirconia) (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 triisobutylaluminum hexane solution (1.0 M, 11 mL) were then added sequentially to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were added sequentially to the reactor. The reactor was heated to 60 °C, and ethylene at 1.5 MPa was introduced. The polymerization reaction was carried out at 200 rpm for 30 minutes with stirring. 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 P2 was weighed. The polymerization activity and polymer test results of this embodiment are shown in Table 1.

[0075] Example 3

[0076] In a glove box, catalyst A2 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconium dichloride) (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to 100 mL Erlenmeyer flasks and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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.

[0077] Example 4

[0078] In a glove box, catalyst A4 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconium dichloride) (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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 P4 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0079]

[0080] Example 5

[0081] In a glove box, catalyst A2 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconium dichloride) (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 4.4 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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 P5 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0082] Example 6

[0083] In a glove box, catalyst A2 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconium dichloride) (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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 P6 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0084] Example 7

[0085] In a glove box, catalyst A2 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconia dichloride) (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 80 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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.

[0086] Example 8

[0087] In a glove box, catalyst A2 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconium dichloride) (0.011 mmol), dichloromethane (10 mL), and triphenylcarbontetra(pentafluorophenyl)borate (0.044 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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 P8 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0088] Example 9

[0089] In a glove box, catalyst A2 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconium dichloride) (0.011 mmol), dichloromethane (10 mL), and N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate (0.044 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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 P9 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0090] Example 10

[0091] In a glove box, catalyst A2 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconia dichloride) (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and dichloroethylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the catalyst solution prepared above and diethylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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.

[0092] Example 11

[0093] In a glove box, catalyst A2 (0.0055 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconia dichloride) (0.0165 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were added sequentially to the reactor. After stirring for 10 minutes, the catalyst solution prepared above and diethylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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 example are shown in Table 1.

[0094] Example 12

[0095] In a glove box, catalyst A2 (0.0165 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconia dichloride) (0.0055 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to 100 mL Erlenmeyer flasks and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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 example are shown in Table 1.

[0096] Example 13

[0097] In a glove box, catalyst A2 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconium dichloride) (0.011 mmol), dichloromethane (10 mL), and methylaluminoxane (22 mmol) were sequentially added to a 100 mL Erlenmeyer flask and mixed for later use. After purging a 2 L high-pressure polymerization reactor with high-purity nitrogen at 100 °C for 2 hours, hexane (1 L) and triisobutylaluminum hexane solution (1.0 M, 11 mL) were sequentially added to the reactor. After stirring for 10 minutes, the catalyst solution prepared above and di-n-hexylzinc hexane solution (1.0 M, 6.6 mL) were sequentially added to the reactor. When the reactor temperature reached 60 °C, ethylene at 1.5 MPa was introduced, and the polymerization reaction was carried out for 30 minutes with stirring at 200 rpm. After the reaction was completed, 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 P13 was weighed. The polymerization activity and polymer test results of this example are shown in Table 1.

[0098] Comparative Example 1

[0099] In a glove box, catalyst A2 (0.011 mmol), catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconium dichloride) (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 triisobutylaluminum hexane solution (1.0 M, 11 mL) were then added sequentially. After stirring for 10 minutes, the prepared catalyst solution was added to the reactor. The reactor was heated to 60 °C, and ethylene at 1.5 MPa was introduced. The polymerization reaction was carried out at 200 rpm for 30 minutes with stirring. 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 P14 was weighed. The polymerization activity and polymer test results for this comparative example are shown in Table 1.

[0100] Comparative Example 2

[0101] In a glove box, catalyst A2 (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 triisobutylaluminum hexane solution (1.0 M, 11 mL) were then added sequentially to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were added sequentially to the reactor. The reactor was heated to 60 °C, and ethylene at 1.5 MPa was introduced. The polymerization reaction was carried out at 200 rpm for 30 minutes with stirring. 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 P15 was weighed. The polymerization activity and polymer test results of this comparative example are shown in Table 1.

[0102] Comparative Example 3

[0103] In a glove box, catalyst B3 (dimethylsilyl-bis-(1-indenyl)zirconia dichloride) (0.022 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 triisobutylaluminum hexane solution (1.0 M, 11 mL) were then added sequentially to the reactor. After stirring for 10 minutes, the prepared catalyst solution and diethylzinc hexane solution (1.0 M, 6.6 mL) were added sequentially to the reactor. The reactor was heated to 60 °C, and ethylene at 1.5 MPa was introduced. The polymerization reaction was carried out at 200 rpm for 30 minutes with stirring. 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 P16 was weighed. The polymerization activity and polymer test results for this comparative example are shown in Table 1.

[0104] Table 1. Polymerization test results for each example and comparative example.

[0105]

[0106] As can be seen from the comparison between the above embodiments and comparative examples, the block polyethylene prepared by using the preparation method of this application has a narrower molecular weight distribution, higher tensile strength and elongation at break, and thus gives the polyethylene material a wider range of applications.

[0107] 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 method for preparing block polyethylene, comprising the step of performing ethylene solution polymerization using ethylene as the sole monomer in a reaction system containing an α-diimine nickel metal complex, a metallocene complex, a co-catalyst, an alkyl zinc chain shuttle, and an organic solvent, wherein the co-catalyst is selected from at least one of alkylaluminum, alkylaluminoxane, haloalkylaluminum, arylborane, and arylborates. in, The α-diimine nickel metal complex is selected from one or more metal complexes of general formula (Ia) or (Ib): (I), (One) In formulas (Ia) and (Ib), R1 and R2 are independently hydrogen, C1-C4 alkyl, C1-C4 haloalkyl, halogen, or C1-C4 alkoxy; n is an integer from 0 to 4; 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; each X is independently selected from halogen, C1-C6 alkyl, or C2-C6 alkenyl, wherein the substituted phenyl has 1 to 5 substituents selected from the group consisting of halogen, C1-C4 alkyl, and C1-C4 haloalkyl. The molar ratio of the α-diimine nickel metal complex to the metallocene complex added to the reaction system, based on the central metal atom, is 1:10 to 10:

1.

2. The preparation method according to claim 1, wherein, The α-diimine nickel metal complex is selected from one or more complexes having the following chemical structural formulas: 。 3. The preparation method according to claim 1 or 2, wherein, The metallocene complex is selected from one or more metal complexes of general formula (II): (II) In formula (II), 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 of the following 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.

4. The preparation method according to claim 3, wherein: In formula (II), R' is methylene, ethylene, isopropylene, diphenylmethylene, dimethylmethylenesilyl or diphenylmethylenesilyl; and Each of the following independently represents an unsubstituted or substituted cyclopentadienyl, fluorenyl, or indene; M is titanium or zirconium; each X is independently selected from halogens, C1-C6 alkyl groups, or C2-C6 alkenyl groups.

5. The preparation method according to claim 1 or 2, wherein: The general structural formula of the co-catalyst alkylaluminum is shown in formula (IIIa). (IIIa) 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 (IIIb) or (IIIc). (IIIb), (IIIc), 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 co-catalyst, alkyl haloaluminum, is shown in formula (IIId). (IIId) In this configuration, each R group is independently selected from C1-C8 alkyl groups, X is a halogen, and n is 1 or 2; and The cocatalysts arylborane and arylborates are selected from one or more of triphenylborane, tri(pentafluorophenyl)borane, triphenylcarbazo(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate, triethylammonium tetra(pentafluorophenyl)borate, trimethylammonium tetraphenylborate, triethylammonium tetraphenylborate, triisopropylammonium tetraphenylborate, tri-n-butylammonium tetraphenylborate, trimethylammonium tetra(4-methylphenyl)borate, triisopropylammonium tetra(4-methylphenyl)borate, trimethylammonium tetra(2,4-dimethylphenyl)borate, triethylammonium tetra(2,4-dimethylphenyl)borate, trimethylammonium tetra(4-trifluoromethylphenyl)borate, tri-n-butylammonium tetra(4-trifluoromethylphenyl)borate, tri-n-butylammonium tetra(pentafluorophenyl)borate, and N,N-diethylphenylammonium tetra(pentafluorophenyl)borate.

6. The preparation method according to claim 1 or 2, wherein: The general structural formula of the co-catalyst alkylaluminum is shown in formula (IIIa). (IIIa) In this context, each of the R groups is independently selected from methyl, ethyl, propyl, butyl, and isobutyl; The general structural formula of the cocatalyst alkylaluminoxane is shown in formula (IIIb) or (IIIc). (IIIb), (IIIc), In this context, each group R is independently selected from methyl and ethyl, and n is any integer in the range of 10-30; The general structural formula of the co-catalyst, alkyl haloaluminum, is shown in formula (IIId). (IIId) In this configuration, each group R is independently selected from methyl, ethyl, propyl, butyl, and isobutyl, X is chlorine or bromine, and n is 1 or 2; and The cocatalysts arylborane and arylborate are selected from one or more of tris(pentafluorophenyl)borane, triphenylcarbazo(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate and triethylammonium tetra(pentafluorophenyl)borate.

7. The preparation method according to claim 1 or 2, wherein: The general structural formula of the co-catalyst alkylaluminum is shown in formula (IIIa). (IIIa) In this context, each group R is independently selected from ethyl and isobutyl; The general structural formula of the cocatalyst alkylaluminoxane is shown in formula (IIIb) or (IIIc). (IIIb), (IIIc), In this context, each group R is independently selected from methyl and ethyl, and n is any integer in the range of 10-30; The general structural formula of the co-catalyst, alkyl haloaluminum, is shown in formula (IIId). (IIId) In this configuration, each group R is independently selected from ethyl and isobutyl, X is chlorine or bromine, and n is 1 or 2; and The cocatalysts arylborane and arylborate are selected from one or more of tris(pentafluorophenyl)borane, triphenylcarbazo(pentafluorophenyl)borate, N,N-dimethylphenylammonium tetra(pentafluorophenyl)borate and triethylammonium tetra(pentafluorophenyl)borate.

8. The preparation method according to claim 1 or 2, wherein, Based on the central metal atom, the molar ratio of the α-diimine nickel metal complex to the metallocene complex added to the reaction system is 4:6 to 6:

4.

9. The preparation method according to claim 1 or 2, wherein: The total amount of the co-catalysts alkylaluminum, alkylaluminoxane, and haloalkylaluminum, based on aluminum atoms, in the reaction system, and the total amount of the α-diimine nickel metal complex and metallocene complex, based on the central metal atoms, have a molar ratio of (10-5000):1; and / or The total amount of the co-catalysts arylborane and arylbordate added to the reaction system, calculated by boron atoms, and the total amount of the α-diimine nickel metal complex and metallocene complex, calculated by the central metal atom, have a molar ratio of (1-10):

1.

10. The preparation method according to claim 1 or 2, wherein: The total amount of the co-catalysts alkylaluminum, alkylaluminoxane, and haloalkylaluminum, based on aluminum atoms, in the reaction system, and the total amount of the α-diimine nickel metal complex and metallocene complex, based on the central metal atoms, have a molar ratio of (500-1000):1; and / or The total amount of the co-catalysts arylborane and arylbordate added to the reaction system, calculated by boron atoms, and the total amount of the α-diimine nickel metal complex and metallocene complex, calculated by the central metal atom, have a molar ratio of (2-5):

1.

11. The preparation method according to claim 1 or 2, wherein, The alkyl zinc chain shuttle is selected from at least one organozinc compound as shown in general structural formula (IV). (IV) Each of the R groups is independently selected from C1-C10 straight-chain or branched alkyl groups.

12. The preparation method according to claim 1 or 2, wherein, The alkyl zinc chain shuttle is selected from at least one organozinc compound as shown in general structural formula (IV). (IV) Each of the groups R is independently selected from at least one of methyl, ethyl, isopropyl, n-butyl, isobutyl and n-hexyl.

13. The preparation method according to claim 1 or 2, wherein, The amount of alkyl zinc chain shuttle added to the reaction system, calculated by zinc atoms, and the total amount of α-diimine nickel metal complex and metallocene complex, calculated by central metal atoms, have a molar ratio of (1-1000):

1.

14. The preparation method according to claim 1 or 2, wherein, The amount of alkyl zinc chain shuttle added to the reaction system, calculated by zinc atoms, is in a molar ratio of (100-500):1 with the total amount of α-diimine nickel metal complex and metallocene complex, calculated by the central metal atom.

15. The preparation method according to claim 1 or 2, wherein the organic solvent is selected from aromatic hydrocarbons, alkanes and haloalkanes.

16. The preparation method according to claim 1 or 2, 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.

17. The preparation method according to claim 1 or 2, wherein the conditions of the polymerization reaction include: Temperature range: 0–150℃; The polymerization pressure is 0.1–4.0 MPa.

18. The preparation method according to claim 1 or 2, wherein the conditions of the polymerization reaction include: Temperature: 60–100℃; Polymerization pressure: 0.5–3.0 MPa.

19. A block polyethylene prepared according to any one of claims 1 to 18, having a weight-average molecular weight of 5-1,000,000 g / mol, a polymer dispersibility index (PDI) of 1.5-4.0, a branching degree of 20-75 / 1000C, and a crystallinity of 5-35%.

20. The block polyethylene according to claim 19, wherein the weight-average molecular weight is 150,000-350,000 g / mol, the polymer dispersibility index (PDI) is 1.8-3.2, the degree of branching is 45-72 / 1000C, and the degree of crystallinity is 7-20%.

21. The block polyethylene according to claim 19, wherein the melting point is... T m Its melting enthalpy Δ is 40-100℃. H It is 10-70 J / g.

22. The block polyethylene according to claim 19, wherein the melting point is... T m Its melting enthalpy Δ is 45-90℃. H It is 15-60 J / g.

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