Polyolefin catalyst as well as ligand, preparation method and application thereof

Abstract

The invention relates to the technical field of polyolefin, in particular to a polyolefin catalyst, a ligand of the polyolefin catalyst and a preparation method and application of the polyolefin catalyst, and the polyolefin catalyst is an alpha-diimine ligand with a general formula structure shown in a formula L. In the formula, R1-R11 are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C12 aryl or halogen respectively. The catalyst with a novel structure is prepared, the catalyst is high in thermal stability and catalytic activity and can be well applied to preparation of the cycloolefin copolymer through catalytic polymerization, the insertion rate of cycloolefin monomers is increased, the glass-transition temperature can be increased, the copolymer has narrow molecular weight distribution, high cycloolefin content and excellent heat resistance, and the catalyst can be applied to preparation of the cycloolefin copolymer through catalytic polymerization. And the requirements of high-end optical materials are met.

Description

Technical Field

[0001] This invention relates to the field of polyolefin technology, and in particular to a polyolefin catalyst, its ligands, its preparation method, and its applications. Background Technology

[0002] Cyclo-Olefin copolymers (COCs) are polymeric materials produced through the copolymerization of cyclic olefin monomers with ethylene or α-olefins. These materials typically exist as colorless granules or flakes. The introduction of cyclic olefin monomers introduces internal stress into the cyclic structure of the molecular structure, which optimizes the crystallinity of traditional polyolefins, thereby improving transparency. COCs not only possess high transparency and high heat resistance but also combine the advantages of both amorphous and crystalline copolymers, such as low water absorption, excellent optical properties, good biocompatibility, and superior processability. These characteristics make COCs an ideal material choice for high-end electronic product displays and pharmaceutical packaging.

[0003] The preparation of COCs mainly employs two methods: Ring-Opening Mechanism Polymerization (ROMP) and metallocene-catalyzed addition polymerization (m-COC). Japanese companies have utilized ROMP technology, employing Grubbs-type catalysts, to achieve the reaction of cyclic olefin monomers with hydrogen, producing highly transparent COC materials. This process involves the breaking and transfer of double bonds in cyclic olefins, forming growing chains. Although ROMP technology offers mild conditions and regular product structures, it requires a subsequent hydrogenation step. On the other hand, m-COC technology uses ethylene and cyclic olefins as raw materials, resulting in lower production costs. However, COCs produced using metallocenes inevitably suffer from high metal residues and poor product sequence controllability. Based on these issues, there is an urgent need to develop novel catalysts with high catalytic activity and high stability to address the problems in current production processes.

[0004] Since cyclic olefin copolymers typically use norbornene or dicyclopentadiene as the cyclic olefin feedstock, both of which possess a certain degree of polarity, they can affect the polymerization process. Later transition metal catalysts, due to their high electronegativity and low oxidation state of their active metals (Fe, Co, Ni, and Pd), can greatly tolerate polar comonomers. Among these, Ni and Pd-based later transition metal catalysts have been shown to catalyze norbornene polymerization, but most are ineffective for the copolymerization of norbornene and ethylene / α-olefins due to the abstraction of β-H atoms during polymerization, which acts as a chain transfer agent. Therefore, designing and synthesizing highly active and selective later transition metal catalysts has become a new direction for promoting the development of COCs. Summary of the Invention

[0005] The purpose of this invention is to provide a polyolefin catalyst, its ligand, its preparation method, and its application in order to solve the above-mentioned problems.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A first aspect of the present invention provides an α-diimine ligand having the general structure shown in Formula L:

[0008]

[0009] Among them, R1-R 11 They can be the same or different groups, R1-R 11 Each is independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C 12 Aryl or halogen.

[0010] The C1-C6 alkyl groups include straight-chain or branched alkyl groups, for example, including but not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl or hexyl, preferably methyl, isopropyl or tert-butyl.

[0011] The C1-C6 alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, pentoxy, or hexoxy.

[0012] The C6-C 12 Aryl is a monovalent aromatic carbocyclic ring system having at least one aromatic ring or at least one of the rings being aromatic rings, such as phenyl, naphthyl or biphenyl.

[0013] As a preferred technical solution, R1-R 11 At least one of them is selected from H, C1-C6 alkyl or halogen.

[0014] More preferably, R4, R 10 R 11 At least one of them is a C1-C6 alkyl group or a halogen, and the halogen is selected from F, Cl, Br, and I.

[0015] In a preferred embodiment of the present invention, the α-diimine ligand is selected from any one of the compounds shown in formulas L1-L4:

[0016]

[0017] The second aspect of the present invention provides a method for preparing the above-mentioned α-diimine ligands, which are prepared by acid catalysis using a 2,3-dihydroacrylidine-4(1H)-one derivative of the general formula shown in Formula I and an aniline derivative of the general formula shown in Formula II as raw materials. The specific reaction formula is as follows:

[0018]

[0019] In the 2,3-dihydroacrylidine-4(1H)-one derivatives of the general formula shown in Formula I, R1-R8 can be the same or different groups, independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, aromatic phenyl, aromatic naphthyl, aromatic biphenyl, halogen, etc. In a preferred embodiment of the present invention, the 2,3-dihydroacrylidine-4(1H)-one derivatives include 2,3-dihydroacrylidine-4(1H)-one and 9-methyl-2,3-dihydroacrylidine-4(1H)-one.

[0020] The aniline derivatives of the general formula II have a primary amine backbone, R9-R 11 The aniline derivative can be the same or different groups, independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, aromatic phenyl, aromatic naphthyl, aromatic biphenyl, halogen, etc. Preferably, a primary amine with an electron-withdrawing effect is used as the amine raw material; more preferably, a primary amine with a low steric hindrance electron-withdrawing group is used. In a preferred embodiment of the present invention, the aniline derivative is selected from aniline, 3,5-dimethylaniline, p-methylaniline, p-bromoaniline, p-trifluoromethylaniline, etc.

[0021] As a preferred technical solution, the preparation method of the α-diimine ligand of the present invention includes the following steps: a 2,3-dihydroacrylidine-4(1H)-one derivative and an aniline derivative are dissolved in an aprotic polar organic solvent at a molar ratio of 1:1.1-2.5, preferably with a molar ratio of 1:1.5-2.3. Subsequently, a non-oxidizing strong organic acid is used as a catalyst (catalytically significant), and the reaction is carried out at 40-150°C for 4-48 hours, preferably at a reaction temperature of 60-100°C for 8-24 hours. After the reaction, the solvent is removed from the mixture and it is purified to obtain the α-diimine ligand.

[0022] Preferably, the organic aprotic polar solvent can be a solvent commonly used in the art, such as benzene or toluene. The non-oxidizing organic strong acid can be a strong organic acid substance commonly used in the art, such as p-toluenesulfonic acid. Solvent removal can be performed using conventional methods in the art, such as rotary evaporation. Product purification can be performed using conventional methods in the art, such as recrystallization or column chromatography.

[0023] A third aspect of the present invention provides a polyolefin catalyst, which is a coordination compound formed by the α-diimine ligands described above and a post-transition metal salt.

[0024] The post-transition metal is selected from Fe, Co, Ni or Pd, preferably Fe, Co or Ni, and more preferably Ni. The post-transition metal salt can be a halide of the post-transition metal, such as a chloride or bromide, including but not limited to ferric chloride, cobalt chloride, nickel bromide, palladium chloride, etc.

[0025] Preferably, the catalyst is a nickel metal catalyst having the general structure shown in Formula C:

[0026]

[0027] In formula C, X is chlorine or bromine;

[0028] Among them, R1-R 11 The definition is as described above, i.e., R1-R 11 They can be the same or different groups, and R1-R9 are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C 12 Aryl or halogen.

[0029] In a preferred embodiment of the present invention, the nickel metal catalyst is selected from any one of the following formulas C1 to C4:

[0030]

[0031]

[0032] In formulas C1-C4, X is chlorine or bromine.

[0033] The polyolefin catalyst of this invention has a 2,3-dihydroacrylidine-4(1H)-one backbone structure. The quinoline backbone and its substituents can regulate the electronic structure of the catalyst system, which helps to optimize the electron cloud density of the metal active center. Simultaneously, the ring strain introduced by the six-membered ring structure coupled to the quinoline unit can optimize the geometry of the metal active center. The synergistic effect of these electronic and geometric effects significantly improves the copolymerization performance of ethylene with comonomers such as cycloolefins, thereby obtaining copolymer products with superior performance.

[0034] The fourth aspect of the present invention provides a method for preparing the above-mentioned catalyst. The catalyst can be prepared by synthesizing coordination compounds. Taking a nickel metal catalyst with the general structure shown in Formula C as an example, the method is as follows: the α-diimine ligand and the nickel salt are dissolved in an anhydrous aprotic organic solvent at a molar ratio of 1:1-4, and reacted in an anhydrous and oxygen-free environment. The specific reaction formula is as follows:

[0035]

[0036] Preferably, the above-mentioned nickel metal catalyst is prepared by the following method: The prepared ligand L and nickel salt are dissolved in an anhydrous aprotic organic solvent (e.g., acetonitrile, toluene, dichloromethane) at a molar ratio of 1:1-4. Preferably, the molar ratio of ligand L to nickel salt is 1:1-1.5. The reaction is carried out in an anhydrous and oxygen-free environment at a reaction temperature of 0-100°C for 8-36 hours. After the reaction is completed, the sample is filtered and washed 2-3 times, and then dried in a vacuum drying oven.

[0037] The fifth aspect of the present invention provides the application of the above-mentioned catalyst in the preparation of cyclic olefin copolymers, wherein the catalyst, in the presence of a co-catalyst, uses ethylene and cyclic olefin monomers (e.g., norbornene, dicyclopentadiene) as raw materials to carry out a polymerization reaction in a solvent at a lower pressure and with high catalytic activity to obtain a cyclic olefin copolymer with excellent performance.

[0038] Furthermore, when preparing the cyclic olefin copolymer, the pressure is 0.01-10 MPa, preferably 0.05-2 MPa; more preferably 0.05-1 MPa; and the reaction temperature is controlled at 50-150℃, preferably 100-130℃.

[0039] Furthermore, the selected solvent is mainly an inert solvent, preferably a C6-C8 straight-chain alkane, benzene and its derivatives, such as benzene, toluene, xylene, chlorobenzene, hexane, pentane and so on.

[0040] Furthermore, the selected co-catalyst is mainly alkylaluminoxane, and more preferably methylaluminoxane, modified methylaluminoxane, diethylaluminum chloride, or isobutylaluminoxane as co-catalyst, wherein the molar ratio of the catalyst to the co-catalyst is 1:50 to 500.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] This invention synthesizes a class of post-transition metal catalysts with a 2,3-dihydroacrylidine-4(1H)-one backbone. The specific mechanism is not yet fully understood, but the inventors speculate that the possible reasons are: its core backbone and substituents (e.g., R...). 11 The electron-withdrawing effect of Br helps to regulate the electronic structure of the metal center. The lone pair electrons of the nitrogen atom in the framework form an extended conjugated system with the benzene ring and diimine unit, reducing the electron cloud density of the nickel center and decreasing Lewis acidity, which is beneficial for the insertion of polar comonomers. At the same time, the low electron density of the metal center weakens the tendency for β-H transfer, inhibiting chain transfer reactions. The synergistic effect of the above electronic effects significantly improves the polymerization efficiency of cyclic olefins (such as norbornene) copolymerization by the catalyst, increasing the insertion rate of cyclic olefin monomers such as norbornene, which helps to increase the glass transition temperature. The resulting cyclic olefin copolymers have a narrow molecular weight distribution, high cyclic olefin content, and excellent heat resistance, meeting the requirements of high-end optical materials. Detailed Implementation

[0043] The following description is provided to disclose the present invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples and are not intended to limit the scope of the invention; other obvious variations will be apparent to those skilled in the art. The basic principles of the invention defined in the following description can be applied to other embodiments, modifications, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the invention. Unless otherwise specified, the instruments or reagents used in the embodiments of the present invention are conventional commercial instruments or reagents.

[0044] The main reagents used in the examples are from the following sources:

[0045] 2,3-Dihydroacrylidine-4(1H)-one CAS: 49568-10-7 Henan Weitixi Chemical Technology

[0046] 9-Methyl-2,3-dihydroacridin-4(1H)-one CAS: 14428-47-8 Sigma-Aldrich

[0047] Aniline CAS: 62-53-3 Sigma-Aldrich

[0048] 3,5-Dimethylaniline CAS: 108-69-0 Sigma-Aldrich

[0049] p-Bromoaniline CAS: 106-40-1 Sigma-Aldrich

[0050] p-Toluenesulfonic acid CAS: 104-15-4Sigma-Aldrich

[0051] Toluene CAS: 108-88-3Sigma-Aldrich

[0052] Norbornene CAS: 498-66-8 Sigma-Aldrich

[0053] 1,2-Cyclohexanedione CAS: 765-87-7Sigma-Aldrich

[0054] Dimethyl sulfoxide CAS: 67-68-5Sigma-Aldrich

[0055] Calcium hydride CAS: 7789-78-8 Sigma-Aldrich

[0056] Sodium Metal CAS: 7440-23-5 Aladdin Reagent

[0057] Benzophenone CAS: 119-61-9 Aladdin Reagent

[0058] Anhydrous sodium sulfate CAS: 7757-82-6 Aladdin Reagent

[0059] 5A molecular sieve CAS: 69912-79-4Sigma-Aldrich

[0060] Hydrochloric acid CAS: 7647-01-0Sigma-Aldrich

[0061] Ethanol CAS: 64-17-5Sigma-Aldrich

[0062] Nickel bromide CAS: 13462-88-9Sigma-Aldrich

[0063] Dimethylsilane (tert-butylamino)tetramethylcyclopentadienyldimethyltitanium CAS: 135072-62-7 Xinnoco Catalysts

[0064] Tris(pentafluorophenyl)borane CAS: 1109-15-5Sigma-Aldrich

[0065] Methylaluminoxane CAS: 120144-90-3 Macklin reagent

[0066] Diethylaluminum chloride CAS: 96-10-6Sigma-Aldrich

[0067] Hydrogen CAS: 1333-74-0 Shanghai Air Liquide

[0068] The toluene used in the experiment needs to be refluxed for 48 hours under a nitrogen atmosphere with the addition of metallic sodium and benzophenone. Dimethyl sulfoxide is refluxed for 12 hours with calcium hydride. Dichloromethane is dried with anhydrous sodium sulfate for more than three days. Norbornene needs to be treated with 5A molecular sieve for more than three days.

[0069] Example 1

[0070]

[0071] Synthesis of ligand L1: 2,3-Dihydroacridin-4(1H)-one (1 mmol, 197.2 mg) was dissolved in 50 mL of toluene solution, followed by the addition of 5 μL of p-toluenesulfonic acid DMSO solution (1 mol / L) as a catalyst, and aniline (2.2 mmol, 204.9 mg). The reaction was refluxed at 120 °C for 12 h. After the reaction was completed, the mixture was cooled to room temperature, and a large amount of ethanol was added to precipitate the crude product. The product was then washed with ethanol and dried under vacuum. The yield was 75%. ¹H NMR (400 MHz CDCl₃): δ = 8.40 (s, 1H Ar-H); δ = 7.88–6.93 (m, 9H Ar-H); δ = 2.71–1.88 (m, 6H CH₂).

[0072]

[0073] Preparation of catalyst C1: The synthesized ligand (1 mmol, 272.1 mg) was reacted with nickel bromide (1.2 mmol, 262.2 mg) in 25 mL of dichloromethane solution at room temperature for 12 hours. After the reaction was completed, the mixture was filtered and dried to obtain catalyst sample C1 with a yield of 95%.

[0074] Example 2

[0075]

[0076] Synthesis of ligand L2: 2,3-Dihydroacridin-4(1H)-one (1 mmol, 197.2 mg) was dissolved in 50 mL of toluene solution, followed by the addition of 5 μL of p-toluenesulfonic acid DMSO solution (1 mol / L) as a catalyst. 3,5-Dimethylaniline (2.2 mmol, 266.6 mg) was refluxed at 120 °C for 12 h. After the reaction was complete, the mixture was cooled to room temperature, and a large amount of ethanol was added to precipitate the crude product. The product was then washed with ethanol and dried under vacuum. The yield was 81%. ¹H NMR (400 MHz CDCl₃): δ = 8.43 (s, 1H Ar-H); δ = 7.88–7.25 (m, 7H Ar-H); δ = 2.71–1.90 (m, 6H CH₂); δ = 2.28 (s, 6H CH₃).

[0077]

[0078] Preparation of catalyst C2: The synthesized ligand (1 mmol, 300.4 mg) was reacted with nickel bromide (1.2 mmol, 262.2 mg) in 25 mL of dichloromethane solution at room temperature for 12 hours. After the reaction was completed, the mixture was filtered and dried to obtain catalyst sample C2 with a yield of 96%.

[0079] Example 3

[0080]

[0081] Synthesis of ligand L3: 2,3-Dihydroacridin-4(1H)-one (1 mmol, 197.2 mg) was dissolved in 50 mL of toluene solution, followed by the addition of 5 μL of p-toluenesulfonic acid DMSO solution (1 mol / L) as a catalyst. The mixture was refluxed at 120 °C for 12 h with p-bromoaniline (2.2 mmol, 378.4 mg). After the reaction was complete, the mixture was cooled to room temperature, and a large amount of ethanol was added to precipitate the crude product. The product was then washed with ethanol and dried under vacuum. The yield was 72%. ¹H NMR (400 MHz CDCl₃): δ = 8.44 (s, 1H Ar-H); δ = 7.85–7.07 (m, 8H Ar-H); δ = 2.70–1.95 (m, 6H-CH₂).

[0082]

[0083] Preparation of catalyst C3: The synthesized ligand (1 mmol, 350.0 mg) was reacted with nickel bromide (1.2 mmol, 262.2 mg) in 25 mL of dichloromethane solution at room temperature for 12 hours. After the reaction was completed, the mixture was filtered and dried to obtain catalyst sample C3 with a yield of 90%.

[0084] Example 4

[0085]

[0086] Synthesis of ligand L4: 9-methyl-2,3-dihydroacrylidine-4(1H)-one (1 mmol, 211.2 mg) was dissolved in 50 mL of toluene solution, followed by the addition of 5 μL of p-toluenesulfonic acid DMSO solution (1 mol / L) as a catalyst. Aniline (2.2 mmol, 204.9 mg) was added and refluxed at 120 °C for 12 h. After the reaction was complete, the mixture was cooled to room temperature, and a large amount of ethanol was added to precipitate the crude product. The product was then washed with ethanol and dried under vacuum. The yield was 82%. ¹H NMR (400 MHz CDCl₃): δ = 8.12–7.12 (m, 9HAr-H); δ = 2.73 (s, 3H-CH₃); δ = 2.50–1.92 (m, 6H-CH₂).

[0087]

[0088] Preparation of catalyst C4: The synthesized ligand (1 mmol, 286.1 mg) was reacted with nickel bromide (1.2 mmol, 262.2 mg) in 25 mL of dichloromethane solution at room temperature for 12 hours. After the reaction was completed, the mixture was filtered and dried to obtain catalyst sample C4 with a yield of 91%.

[0089] Table 1 Catalysts and their preparation raw materials

[0090]

[0091] Catalyst Application Examples

[0092] The obtained catalyst samples were used for catalytic polymerization to prepare cyclic olefin copolymers, and all operations involved were performed using standard Schlenk techniques.

[0093] A 250ml stainless steel reactor equipped with a magnetic stirrer was used as the reactor and baked in an oven for 3 hours before use. Approximately 50ml of anhydrous toluene solution was added to the reactor as a solvent, followed by the comonomer norbornene (10mmol, 0.942g) and the cocatalyst methylaluminoxane (200μmol). Ethylene gas was injected, and the pressure inside the reactor was controlled at 0.10MPa. The polymerization temperature was then maintained at 60℃ with stirring to ensure homogeneous mixing of the reactants. A toluene solution containing 2μmol of catalyst (catalyst C1-C4) was added via syringe to initiate the reaction. After 1 hour of reaction, unreacted catalyst was quenched with a 10% HCl-MeOH solution. The resulting polymer was filtered, washed with ethanol, and vacuum dried to obtain the copolymer product.

[0094] Comparative Example 1

[0095] Using a commercially available CGC-type catalyst (dimethylsilane(tert-butylamino)tetramethylcyclopentadienyldimethyltitanium) as catalyst sample D1, replacing the catalyst sample of the present invention, cyclic olefin copolymers were prepared in the same manner.

[0096] Comparative Example 2

[0097] The cyclic olefin copolymers were prepared by replacing the catalyst in the embodiments of the present invention with a conventional α-diimine nickel-type post-transition metal catalyst, following the same method. The α-diimine nickel-type catalyst was obtained by the following method:

[0098]

[0099] 1,2-Cyclohexanedione (1 mmol, 112.1 mg) was dissolved in 50 mL of toluene solution upon heating, followed by the addition of 5 μL of p-toluenesulfonic acid DMSO solution (1 mol / L) as a catalyst. Aniline (2.2 mmol, 204.9 mg) was added and refluxed at 120 °C for 12 h. After the reaction was complete, the mixture was cooled to room temperature, and a large amount of ethanol was added to precipitate the crude product. The product was then washed with ethanol and dried under vacuum. The yield was 77%. ¹H NMR (400 MHz CDCl₃) δ = 7.73–7.05 (m, 8H Ar-H); δ = 2.55–1.78 (m, 8H CH₂).

[0100]

[0101] The synthesized ligand (1 mmol, 418.0 mg) was reacted with nickel bromide (1.2 mmol, 262.2 mg) in 25 mL of dichloromethane solution at room temperature for 12 hours. After the reaction was completed, the mixture was filtered and dried to obtain catalyst sample D2 with a yield of 93%.

[0102] Catalyst activity was calculated based on the yield of cyclic olefin copolymers, expressed as g copolymer / (mol catalyst × h). Table 2 lists the catalytic activity of each catalyst.

[0103] Table 2 Catalytic activity of catalysts (unit: g / (mol·h))

[0104] Group Copolymer yield (g) Catalytic activity (g / mol·h) Sample C1 3.88 <![CDATA[1.94×10 6 ]]> Sample C2 5.29 <![CDATA[2.65×10 6 ]]> Sample C3 7.54 <![CDATA[3.77×10 6 ]]> Sample C4 3.04 <![CDATA[1.52×10 6 ]]> Sample D1 2.52 <![CDATA[1.26×10 6 ]]> Sample D2 0.29 <![CDATA[1.45×10 5 ]]>

[0105] As shown in Table 2, the α-diimine catalysts in the examples can polymerize at higher temperatures and have higher catalytic activity in the copolymerization of ethylene and norbornene compared to traditional CGC-type catalysts and traditional α-diimine catalysts.

[0106] [Performance Testing of Cyclic Olefin Copolymer Products]

[0107] The performance of the obtained cyclic olefin copolymers was tested, including:

[0108] 1. Molecular weight determination: including weight-average molecular weight (Mw) and number-average molecular weight (Mn), determined by gel permeation chromatography according to GB / T27843-2011 "Determination of Low Molecular Weight Components of Polymers in Chemicals - Gel Permeation Chromatography (GPC)".

[0109] 2. Determination of cyclic olefin monomer content: This is calculated using the 1H NMR spectrum of the copolymer product. 1 HNMR mainly produces two types of hydrogen: one is the bridgehead proton hydrogen formed after norbornene inserts into the copolymer backbone at 2.10-1.50 ppm; the other is the residual hydrogen at 1.50-0.70 ppm.

[0110] The concentration of cyclic olefins in the copolymer is calculated using the formula: Norbornene (mol%) = a / b × 100%, where a is the integral of the bridgehead hydrogen signal (calculated from the signal at 2.10-1.50 ppm) and b is the integral of the remaining hydrogen signal (calculated from the signal at 1.50-0.70 ppm).

[0111] 3. Glass transition temperature (Tg) determination: According to GB / T 19466.2-2004: Differential scanning calorimetry (DSC) for plastics - Part 2: Determination of glass transition temperature.

[0112] Table 3 Performance of Examples and Comparative Examples

[0113] Serial Number <![CDATA[Mw(×10 5 )]]> PDI Cyclic olefin content (mol%) Tg (°C) Example 1 24.4 1.80 35.22 118.6 Example 2 26.7 1.92 33.42 123.5 Example 3 31.6 1.77 38.55 129.8 Experiment Example 4 22.1 1.85 31.95 114.9 Comparative Example 1 18.4 2.04 28.74 108.6 Comparative Example 2 6.3 2.75 8.62 87.5

[0114] As shown in Table 3, the cyclic olefin copolymers prepared using the catalysts of the embodiments of the present invention all have a weight-average molecular weight greater than 200,000, the comonomer content is controlled above 30%, and the Tg is maintained in the range of 114-130℃. Compared with the comparative examples, the performance is better, especially Example 3, which has the best performance. On the one hand, this shows that the electron-withdrawing bromine-substituted ligands optimize through electronic effects, reduce the Lewis acidity of the metal center, weaken β-H migration, and increase the molecular weight of the copolymer. On the other hand, it shows that the 2,3-dihydroacrylidine-4(1H)-one structure changes the leftmost benzene ring structure compared with the anthracene ring, reducing the volume of the buried active center, which is more conducive to achieving efficient insertion of norbornene. In contrast, the metallocene catalyst used in Comparative Example 1 has a reduced content of restricted cyclic olefin insertion and significant chain transfer, resulting in a larger PDI. Comparative Example 2 uses a traditional α-diimine catalyst, which hinders molecular weight growth, reduces Mw, and has low cyclic olefin insertion efficiency.

[0115] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. An α-diimine ligand having the general structure shown in Formula L: in, R1-R 11 Each is independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C 12 Aryl or halogen.

2. The α-diimine ligand according to claim 1, characterized in that, R1-R 11 At least one of them is selected from H, C1-C6 alkyl or halogen.

3. The α-diimine ligand according to claim 2, characterized in that, R4, R 10 R 11 At least one of them is a C1-C6 alkyl group or a halogen, and the halogen is selected from F, Cl, Br, and I.

4. The α-diimine ligand according to claim 1, characterized in that, The α-diimine ligands are selected from any one of the compounds shown in formulas L1 to L4:

5. The method for preparing α-diimine ligands according to any one of claims 1-4, characterized in that, The acridine-4(1H)-one derivative with the general structure shown in Formula I and the aniline derivative with the general structure shown in Formula II were prepared by acid catalysis. The specific reaction formula is as follows:

6. The method for preparing α-diimine ligands according to claim 5, characterized in that, The preparation method of α-diimine ligands includes the following steps: 2,3-dihydroacrylidine-4(1H)-one derivative and aniline derivative are dissolved in an aprotic polar organic solvent at a molar ratio of 1:1.1-2.5, and reacted at 40-150℃ for 4-48h using a non-oxidizing strong organic acid as a catalyst. After the reaction is completed, the solvent is removed from the mixture and it is purified to obtain the α-diimine ligand.

7. A polyolefin catalyst, characterized in that, It is a coordination compound formed by the α-diimine ligand as described in any one of claims 1-4 and a post-transition metal salt.

8. A polyolefin catalyst according to claim 7, characterized in that, The polyolefin catalyst is a nickel metal catalyst having the general structure shown in Formula C: In the formula, X is chlorine or bromine.

9. The use of the polyolefin catalyst according to claim 7 or 8 in the preparation of cyclic olefin copolymers.

10. The application of the polyolefin catalyst according to claim 9 in the preparation of cyclic olefin copolymers, characterized in that, The catalyst, under the action of a co-catalyst, uses ethylene and cyclic olefin monomers as raw materials to carry out a polymerization reaction in a solvent to prepare cyclic olefin copolymers.

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