A polar modified high-purity polyethylene, its preparation method and application

Abstract

This invention relates to the field of polyethylene technology, specifically to a polar-modified high-purity polyethylene, its preparation method, and its applications. The method includes the following steps: In the presence of a nickel phosphonate catalyst, ethylene is polymerized with a polar monomer to obtain polar-modified polyethylene. The nickel phosphonate catalyst has the structure shown in Formula C. This invention, by employing a novel nickel phosphonate catalyst, improves the catalyst's tolerance to polar comonomers, increases the insertion rate of polar groups, and prepares polar-modified high / ultra-high molecular weight polyethylene, thereby improving the properties of polyethylene.

Description

Technical Field

[0001] This invention relates to the field of polyolefin technology, specifically to a polar modified high-purity polyethylene, its preparation method, and its applications. Background Technology

[0002] Polyethylene (PE) has become one of the most widely used polymer materials due to its comprehensive advantages, including low relative density, chemical resistance, water resistance, mechanical strength, and electrical insulation. With the development of technology and industry, high-end polyolefin materials, represented by high-purity PE, are increasingly prominent in cutting-edge fields such as new energy, semiconductor manufacturing, and biomedicine. However, the PE molecular chain is mainly composed of non-polar hydrocarbon structures, resulting in low surface energy, poor hydrophilicity, and poor adhesion, compatibility, and dyeability with polar materials (such as polar polymers). This deficiency hinders its application in many fields. Therefore, effective functional modification of PE is expected to improve its surface polarity, increase its added value, and expand its application range.

[0003] To expand the application range of polyethylene, polar modification has become a research hotspot. Common modification methods include physical blending, surface treatment, and chemical grafting. Among these, copolymerizing ethylene with some polar monomers (such as acrylic acid, vinyl acetate, acrylates, carbon monoxide, etc.) can introduce polar groups into the polyethylene chain. This introduction of polar groups at the molecular level is considered an effective way to achieve permanent and uniform modification. For example, by copolymerizing ethylene with carbon monoxide, carbonyl groups can be introduced into the polymer backbone, enabling the preparation of polymer materials with high strength, high rigidity, high heat resistance, gas barrier properties, solvent resistance, and fatigue resistance.

[0004] However, copolymerizing ethylene with polar monomers is not easy, and obtaining high-molecular-weight polar polyolefins is even more difficult. Due to the differences in polymerization mechanisms between polar monomers and olefins, traditional Ziegler-Natta catalysts or metallocene catalysts often face problems such as low catalytic activity, low comonomer insertion rate, and difficulty in controlling polymer molecular weight and distribution when catalyzing such copolymerization reactions. This results in poor performance of the obtained copolymers, making it difficult to prepare high-purity, high-performance polar modified polyethylene. Therefore, developing a method that can efficiently catalyze the copolymerization of olefins and polar monomers to prepare high-purity and excellent-performance polar modified polyethylene has significant industrial value and importance. Summary of the Invention

[0005] The purpose of this invention is to provide a polar modified high-purity polyethylene, its preparation method, and its application in order to solve the above-mentioned problems, such as low catalytic efficiency and poor controllability of copolymer structure in the preparation process of polar modified polyethylene in the prior art.

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

[0007] A method for preparing polar modified high-purity polyethylene includes the following steps:

[0008] In the presence of a nickel phosphonate catalyst, ethylene is polymerized with a polar monomer to obtain polar modified polyethylene, wherein the nickel phosphonate catalyst has the structure shown in Formula C:

[0009]

[0010] R1-R4 are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, and C6-C4, respectively. 12 Aryl or halogen. Preferably, in R1-R4, R1 and R2 are selected from the same group, and R3 and R4 are selected from the same group. More preferably, R3 and R4 are H, and R1 and R2 are each selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, and C6 aryl.

[0011] In a preferred embodiment of the present invention, the nickel phosphonate catalyst is selected from any one of the following formulas C1 to C3:

[0012]

[0013]

[0014] .

[0015] As a preferred technical solution, the polar monomer is selected from one or more olefin monomers containing hydroxyl, carbonyl, carboxyl, ester, epoxy, anhydride, or amide groups, including methyl acrylate, ethyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, butyl methacrylate, glycidyl methacrylate, vinyl acetate, ethylene tert-carbonate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, allyl alcohol, maleic anhydride, glycidyl acrylate, allyl glycidyl ether, acrylamide, methacrylamide, N-hydroxymethylacrylamide, N-isopropylacrylamide, and carbon monoxide. In a preferred embodiment of the present invention, the polar monomer may be carbon monoxide.

[0016] As a preferred technical solution, ethylene and polar monomers are polymerized in a closed stirred reactor containing an inert organic solvent at a pressure of 0.1-10 MPa and a reaction temperature of 50-150℃.

[0017] The molar ratio of ethylene to the polar monomer is 2-12:1;

[0018] The concentration of the nickel phosphonate catalyst in the solvent is 0.1-1 mmol / L.

[0019] Preferably, the pressure is 0.5-6 MPa, more preferably 1-5.5 MPa;

[0020] Preferably, the reaction temperature is 60-100℃, and more preferably 70-85℃.

[0021] Preferably, the molar ratio of ethylene to the polar monomer is 8-10:1;

[0022] Preferably, the concentration of the nickel phosphonate catalyst in the solvent is 0.3-0.6 mmol / L.

[0023] As a preferred technical solution, the inert organic solvent is selected from one or more of aromatic hydrocarbons, alkanes, and halogenated hydrocarbons, such as benzene, toluene, xylene, chlorobenzene, hexane, pentane, etc.

[0024] A polar modified high-purity polyethylene is prepared by the preparation method described above, wherein the polyethylene has a weight-average molecular weight of 900,000 to 1,100,000 and an insertion rate of 3 to 7 mol of polar monomers.

[0025] The aforementioned polar modified high-purity polyethylene is used in the preparation of engineering plastics, fiber materials, high-barrier materials, or functional coatings. Engineering plastics include automotive engineering plastics, electronic and electrical engineering plastics, or mechanical structural engineering plastics; fiber materials include industrial fibers, protective fibers, textiles, or reinforcing fibers; high-barrier materials include food packaging films, pharmaceutical packaging materials, fuel barrier layers, or gas barrier films; functional coatings include metal bonding coatings, anti-corrosion coatings, hydrophilic coatings, or printable coatings; it can also be used to prepare polymer alloy materials, as a compatibilizer to improve the interfacial compatibility between non-polar polymers and polar polymers; or to prepare 3D printing materials for additive manufacturing.

[0026] The nickel phosphononsulfonate catalyst described above in this invention is a coordination compound formed by a phosphononsulfonic acid ligand with a corresponding structure and an organonitrile complex. In the structure of the nickel phosphononsulfonate catalyst used in this invention, the P atom and N atom are connected in the 1,3,2-diazaphosphonidine five-membered ring ligand. The lone pair electrons on the N atom and the substituents improve the electronic structure of the P atom. The substituents on the N atom further affect the steric hindrance of the active center, which has an impact on the subsequent insertion of polar monomers. The two work together to promote the copolymerization of ethylene and polar monomers with Ni as the active center in the phosphononsulfonic acid type catalyst, obtaining polyolefins with high polar monomer insertion rate and high molecular weight.

[0027] The nickel phosphonosulfonate catalyst described above can be prepared by synthesizing coordination compounds: a phosphonosulfonate ligand and an organonitrile complex (such as allyl nickel chloride) 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:

[0028] .

[0029] Preferably, the catalyst is prepared by the following method: Under inert gas protection, ligand L and the organonickel complex 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 the organonickel complex is 1:1-1.5. The reaction is carried out in an anhydrous and oxygen-free environment at a reaction temperature of 0-60 °C for 8-36 h under the action of an alkaline reagent (e.g., Na₂CO₃). After the reaction is completed, the product is obtained by post-processing separation and purification.

[0030] Preferably, solvent removal can be performed using conventional methods in the art, such as vacuum evaporation; product purification can be performed using conventional methods in the art, such as diatomaceous earth filtration, ether recrystallization, etc.

[0031] The phosphonic acid ligands described above have the general formula structure shown in formula L:

[0032]

[0033] Wherein, R1-R4 can be the same or different groups, and are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C 12 Aryl or halogen. The C1-C6 alkyl group comprises a straight-chain or branched alkyl group, for example, including but not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, or hexyl, preferably methyl. The C1-C6 alkoxy group comprises methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, pentoxy, or hexoxy. 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 or m-xylyl.

[0034] As a preferred technical solution, in R1-R4, R1 and R2 are selected from the same group, and R3 and R4 are selected from the same group. More preferably, R3 and R4 are H, and R1 and R2 are selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, and C6 aryl.

[0035] In a preferred embodiment of the present invention, the phosphonic acid ligand is selected from any one of the compounds represented by formulas L1-L3:

[0036]

[0037]

[0038] .

[0039] The above-described method for preparing phosphonic acid ligands involves a nucleophilic substitution reaction using benzenesulfonic acid of formula I and a 1,3,2-diazaphosphonic acid derivative of formula II as raw materials. The specific reaction formula is as follows:

[0040] .

[0041] In the 1,3,2-diazaphosphonic derivatives with the general formula shown in Formula II, the definitions of R1-R4 are as described above.

[0042] In a preferred embodiment of the present invention, the 1,3,2-diazaphosphonium derivative may be selected from 2-chloro-1,3-diphenyl-1,3,2-diazaphosphonium, 2-chloro-1,3-bis(2,6-dimethylphenyl)-1,3,2-diazaphosphonium, or 2-chloro-1,3-dimethyl-1,3,2-diazaphosphonium.

[0043] As a preferred technical solution, the preparation method of the phosphonic acid ligand of the present invention specifically includes the following steps: under an inert atmosphere and at low temperature, a base reagent and benzenesulfonic acid are reacted in a solvent to generate a benzenesulfonic acid intermediate; the obtained benzenesulfonic acid intermediate is reacted with a 1,3,2-diazaphosphonic acid derivative in an organic solvent to generate a nucleophilic substitution reaction to generate a product; and the product is obtained by post-processing separation and purification to obtain the phosphonic acid ligand.

[0044] Preferably, the alkaline reagent is an organolithium reagent, including one of n-butyllithium, tert-butyllithium, methyllithium, or phenyllithium, with n-butyllithium being the most preferred. Preferably, the organolithium reagent is dissolved in a solvent (e.g., an inert alkane solvent, such as n-hexane) beforehand.

[0045] Preferably, the organic solvent used is a polar aprotic solvent capable of dissolving the reactants, and commonly used solvents in the art, such as tetrahydrofuran, can be used.

[0046] Preferably, the molar ratio of benzenesulfonic acid, 1,3,2-diazaphosphonic acid derivative and organolithium reagent is 1:1:1.2-2.5.

[0047] Preferably, solvent removal can be performed using conventional methods in the art, such as vacuum evaporation; product purification can be performed using conventional methods in the art, such as column chromatography.

[0048] As a typical preparation example, the preparation method of the phosphonic acid ligand of the present invention is as follows: under nitrogen protection, at 0°C, a hexane solution containing n-butyllithium is slowly added dropwise to a tetrahydrofuran solution containing benzenesulfonic acid, and the reaction is carried out for 1-3 h. Then, a tetrahydrofuran solution containing a 1,3,2-diazaphosphonic acid derivative (such as 2-chloro-1,3-diphenyl-1,3,2-diazaphosphonic acid) is added dropwise to the mixed solution using a constant pressure dropping funnel. The reaction is then slowly raised to room temperature for 2-18 h. After the reaction is completed, the solvent is removed under reduced pressure, and the product is obtained by separation and purification by column chromatography.

[0049] Compared with the prior art, the present invention has the following beneficial effects:

[0050] This invention addresses the problems of low catalytic efficiency and poor controllability of copolymer structure in the preparation of polar modified polyethylene in existing technologies. It utilizes a novel nickel phosphonate catalyst with a novel structure to prepare polar modified high / ultra-high molecular weight polyethylene via solution polymerization. The nickel phosphonate catalyst is a novel Drent-type catalyst composed of benzenesulfonic acid and 1,3,2-diazaphosphonic acid. 1,3,2-diazaphosphonic acid forms the backbone, containing two nitrogen atoms directly bonded to phosphorus (P) atoms. The lone pair electrons on the nitrogen atoms and the attached substituents effectively improve the electronic state of the P atoms, ultimately affecting the oxygen affinity of the Ni active center and enhancing the catalyst's tolerance to polar comonomers. Through the combined effects of electronic effects and steric hindrance, the oxygen affinity of the Ni active center is reduced, and the insertion rate of polar groups is increased, which facilitates the preparation of polar modified high / ultra-high molecular weight polyethylene. Detailed Implementation

[0051] 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.

[0052] The main reagents used in the examples are from the following sources:

[0053] Benzenesulfonic acid CAS: 98-11-3

[0054] CAS number for n-butyllithium: 109-78-8

[0055] Tetrahydrofuran CAS: 109-99-9

[0056] n-Hexane CAS: 110-54-3

[0057] Toluene CAS: 108-88-3

[0058] Ethylene CAS: 74-85-1

[0059] Dichloromethane CAS: 75-09-2

[0060] Allyl nickel(II) chloride dimer CAS: 12145-00-5

[0061] 2-Chloro-1,3-diphenyl-1,3,2-diazaphosphonium CAS: 82017-87-6

[0062] 2-Chloro-1,3-bis(2,6-dimethylphenyl)-1,3,2-diazaphosphonium CAS: 674783-84-7

[0063] 2-Chloro-1,3-dimethyl-1,3,2-diazaphosphonium CAS: 6069-36-9

[0064] Dimethylsilane (tert-butylamino)tetramethylcyclopentadienyldimethyltitanium CAS: 135072-62-7

[0065] 2-(Diphenylphosphino)benzenesulfonic acid CAS: 111864-25-6

[0066] Unless otherwise specified, all solvents involved must be anhydrous.

[0067] [Preliminary Example] Preparation of Ligands and Catalysts

[0068] Preliminary Example 1

[0069] The ligand L1 was prepared, and its structural formula is as follows:

[0070]

[0071] The synthetic route is as follows:

[0072]

[0073] The specific preparation method is as follows: Under nitrogen protection, at 0℃, 5 ml of n-hexane solution containing n-butyllithium (2 mmol, 128 mg) was slowly added dropwise to 10 ml of tetrahydrofuran solution containing benzenesulfonic acid (1 mmol, 158 mg). The reaction was allowed to proceed for 1 h. Then, 5 ml of tetrahydrofuran solution containing 2-chloro-1,3-diphenyl-1,3,2-diazaphosphadin (1 mmol, 276.7 mg) was added dropwise to the mixed solution using a constant pressure dropping funnel. The mixture was then slowly heated to room temperature and reacted for 4 h. After the reaction was completed, the solvent was removed under reduced pressure, and the product sample L1 was obtained by column chromatography with a yield of 47%. 1H (400 MHz, CDCl3) δ=8.46(s,1H -OH); δ=7.80-7.50(m,4H -Ar-H); δ=7.17-6.84(m,10H -Ar-H); δ=3.41(m,4H -CH2).

[0074] Catalyst C1 was prepared, with the following structural formula:

[0075]

[0076] The synthetic route is as follows:

[0077]

[0078] The specific preparation method is as follows: Ligand L1 (0.384 g, 1.00 mmol) and Na2CO3 (0.42 g, 2.00 mmol) were dissolved in 10 mL of DCM in a glove box and reacted at room temperature for 2 h. Allyl nickel chloride (0.30 g, 1.10 mmol) was then added, and the reaction was continued at room temperature for 10 h. After filtration through diatomaceous earth, the resulting liquid was dried under vacuum. A mixed solution of dichloromethane and n-hexane was added, and the mixture was stirred for 10–15 min before filtration to obtain catalyst C1, with a yield of 76%.

[0079] Preliminary Example 2

[0080] The ligand L2 was prepared, and its structural formula is as follows:

[0081]

[0082] The synthetic route is as follows:

[0083]

[0084] The specific preparation method is as follows: Under nitrogen protection, at 0℃, 5 ml of n-hexane solution containing n-butyllithium (2 mmol, 128 mg) was slowly added dropwise to 10 ml of tetrahydrofuran solution containing benzenesulfonic acid (1 mmol, 158 mg). The reaction was allowed to proceed for 1 h. Then, 5 ml of tetrahydrofuran solution containing 2-chloro-1,3-bis(2,6-dimethylphenyl)-1,3,2-diazaphosphazene (1 mmol, 332.8 mg) was added dropwise to the mixed solution using a constant pressure dropping funnel. The mixture was then slowly heated to room temperature and reacted for 5 h. After the reaction was completed, the solvent was removed under reduced pressure, and the product sample L2 was obtained by column chromatography with a yield of 33%. 1H (400 MHz, CDCl3) δ=8.52(s,1H-OH); δ=7.80-7.64(m,4H-Ar-H); δ=6.97-6.82(m,6H-Ar-H); δ=3.26(s,4H-CH2); δ=2.13(s,6H-CH3).

[0085] Catalyst C2 was prepared, with the following structural formula:

[0086]

[0087] The synthetic route is as follows:

[0088]

[0089] The specific preparation method is as follows: Ligand L2 (0.432 g, 1.00 mmol) and Na2CO3 (0.42 g, 2.00 mmol) were dissolved in 10 mL of DCM in a glove box and reacted at room temperature for 2 h. Allyl nickel chloride (0.30 g, 1.10 mmol) was then added, and the reaction was continued at room temperature for 10 h. After filtration through diatomaceous earth, the resulting liquid was dried under vacuum. A mixed solution of dichloromethane and n-hexane was added, and the mixture was stirred for 10–15 min before filtration to obtain catalyst C2, with a yield of 80%.

[0090] Preliminary Example 3

[0091] The ligand L3 was prepared, and its structural formula is as follows:

[0092]

[0093] The synthetic route is as follows:

[0094]

[0095] The specific preparation method is as follows: Under nitrogen protection, at 0℃, 5 ml of n-hexane solution containing n-butyllithium (2 mmol, 128 mg) was slowly added dropwise to 10 ml of tetrahydrofuran solution containing benzenesulfonic acid (1 mmol, 158 mg). The reaction was allowed to proceed for 1 h. Then, 5 ml of tetrahydrofuran solution containing 2-chloro-1,3-dimethyl-1,3,2-diazaphosphazene (1 mmol, 152.56 mg) was added dropwise to the mixed solution using a constant pressure dropping funnel. The mixture was then slowly heated to room temperature and reacted for 4 h. After the reaction was completed, the solvent was removed under reduced pressure, and the product sample L3 was obtained by column chromatography with a yield of 40%. 1H (400 MHz, CDCl3) δ=8.50(s,1H -OH); δ=7.80-7.53(s,4H -Ar-H); δ=2.66(s,4H -CH2); δ=2.46(s,6H -CH3).

[0096] Catalyst C3 was prepared, with the following structural formula:

[0097]

[0098] The synthetic route is as follows:

[0099]

[0100] The specific preparation method is as follows: Ligand L3 (0.258 g, 1.00 mmol) and Na2CO3 (0.42 g, 2.00 mmol) were dissolved in 10 mL of DCM in a glove box and reacted at room temperature for 2 h. Allyl nickel chloride (0.30 g, 1.10 mmol) was then added, and the reaction was continued at room temperature for 10 h. After filtration through diatomaceous earth, the resulting liquid was dried under vacuum. A mixed solution of dichloromethane and n-hexane was added, and the mixture was stirred for 10–15 min before filtration to obtain catalyst C3, with a yield of 85%.

[0101] Example 1

[0102] The obtained catalyst C1 was used to polymerize ethylene with the polar monomer carbon monoxide to produce an ethylene / CO copolymer. The synthesis steps were as follows: Under argon protection, nickel phosphonate catalyst (catalyst C1, 10 μmol) and 20 mL of toluene were added sequentially to a 75 mL autoclave equipped with a magnetic stirrer, and the autoclave was tightened. At room temperature, the autoclave was connected to the polymerization pipeline, and a C2H4 / CO mixture (molar ratio 9:1) with a total pressure of 5 MPa was introduced, and the mixture was stirred for 2 min until the gas in the autoclave was completely saturated. The pipeline was disconnected, and the autoclave was slowly placed in an 80 °C oil bath with magnetic stirring to carry out the polymerization reaction. After the reaction was completed for 3 h, the autoclave was cooled, the remaining gas in the autoclave was slowly released, anhydrous methanol was added to quench the reaction, the mixture was filtered, the solid polymer product was collected, and the product was dried under vacuum at 55 °C overnight. The yield was calculated by weighing.

[0103] Example 2

[0104] Compared to Example 1, catalyst C1 was replaced with catalyst C2, and all other steps were the same.

[0105] Example 3

[0106] Compared to Example 1, catalyst C1 was replaced with catalyst C3, and all other steps were the same.

[0107] Comparative Example 1

[0108] Compared with Example 1, catalyst D was used, which is a commercially available metallocene catalyst (dimethylsilane (tert-butylamino)tetramethylcyclopentadienyldimethyltitanium), and the co-catalyst was methylaluminoxane MAO (the molar ratio of metallocene catalyst to co-catalyst was 1:75). The rest was the same as in Example 1. As a result, only a small amount of high molecular weight polyethylene was generated, and no ethylene / CO copolymer was effectively generated.

[0109] Comparative Example 2

[0110] Compared to Example 1, catalyst C1 was replaced with catalyst Cat-Ref, and all other steps were the same.

[0111] The catalyst Cat-Ref is synthesized based on the phosphonic acid ligand structure. Its structure is (2-(diphenylphosphono)benzenesulfonic acid)nickel(II)-allyl complex, which has a similar [P,O] coordination mode to the catalyst in the example. However, it uses a benzene ring to improve the electronic structure of the active metal center. Compared with the 1,3,2-diazaphosphonic acid structure of the present invention, the electron density of the active center is reduced, which hinders its copolymerization performance with polar monomers.

[0112]

[0113] The specific synthesis method is as follows: In a glove box, 2-(diphenylphosphino)benzenesulfonic acid (0.35 g, 1.00 mmol) and Na₂CO₃ (0.42 g, 2.00 mmol) were added to 10 mL of dichloromethane and reacted at room temperature for 2 h. Then, allyl nickel chloride (0.30 g, 1.10 mmol) was added and reacted at room temperature for 10 h. After filtration through diatomaceous earth and vacuum drying, a mixed solution of dichloromethane and n-hexane was added, stirred, and filtered to obtain the catalyst Cat-Ref in approximately 75% yield.

[0114] [Performance Evaluation Test]

[0115] 1. Catalyst activity test: Calculated based on polymer yield, expressed as g copolymer / (mol catalyst × h).

[0116] 2. Determination of weight-average molecular weight of copolymer samples: The weight-average molecular weight was determined by gel permeation chromatography in accordance with GB / T 27843-2011 "Determination of low molecular weight components of polymers in chemicals - Gel permeation chromatography (GPC)".

[0117] 3. Determination of CO monomer content in copolymer samples: Calculated using the proton NMR spectrum of the copolymer product.

[0118] 4. Ash content test of copolymer samples: Tested according to standard GB / T 9345.1 / 2008.

[0119] For detailed results, please refer to Table 1.

[0120] Table 1 Performance Evaluation Test Results

[0121]

[0122] Note: Comparative Example 1 produced only a very small amount of product, and no relevant tests were performed.

[0123] As shown in Table 1, the embodiments of the present invention yielded polyethylene with a moderate CO insertion rate (3-7 mol%) and high molecular weight (weight average molecular weight of 920,000-1,060,000), and extremely low ash content (≤40 ppm), classifying it as high-purity polyethylene. The catalyst used in the embodiments exhibits good catalytic activity in the copolymerization of ethylene and polar monomers, effectively solving the problem of deactivation of existing catalysts due to poisoning by polar monomers. In Comparative Example 1, the metallocene catalyst was almost completely deactivated in the presence of the polar monomer CO, failing to generate copolymers, indicating its high sensitivity to polar monomers and its unsuitability for ethylene / CO copolymerization. Although Comparative Example 2 could catalyze the copolymerization reaction, its catalytic activity, molecular weight, and CO insertion rate were significantly lower, indicating that the lack of electronic regulation by the 1,3,2-diazaphosphonic acid skeleton significantly reduced catalytic efficiency and copolymerization performance.

[0124] 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. A method for preparing polar-modified high-purity polyethylene, characterized in that, Includes the following steps: In the presence of a nickel phosphonate catalyst, ethylene is polymerized with a polar monomer to obtain polar modified polyethylene, wherein the nickel phosphonate catalyst has the structure shown in Formula C: R1-R4 are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, and C6-C4, respectively. 12 Aryl or halogen.

2. The preparation method according to claim 1, characterized in that, In R1-R4, R1 and R2 are selected from the same group, and R3 and R4 are selected from the same group.

3. The preparation method according to claim 1, characterized in that, R3 and R4 are H, and R1 and R2 are both selected from one of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, and C6 aryl.

4. The preparation method according to claim 1, characterized in that, The nickel phosphononsulfonate catalyst is selected from any one of the following formulas C1 to C3: 。 5. The preparation method according to claim 1, characterized in that, The polar monomer is selected from one or more olefin monomers containing hydroxyl, carbonyl, carboxyl, ester, epoxy, acid anhydride or amide groups.

6. The preparation method according to claim 5, characterized in that, The polar monomers include methyl acrylate, ethyl acrylate, butyl acrylate, hydroxyethyl acrylate, methyl methacrylate, butyl methacrylate, glycidyl methacrylate, vinyl acetate, vinyl tert-carbonate, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, allyl alcohol, maleic anhydride, glycidyl acrylate, allyl glycidyl ether, acrylamide, methacrylamide, N-hydroxymethylacrylamide, N-isopropylacrylamide, and carbon monoxide.

7. The preparation method according to claim 1, characterized in that, The polymerization reaction of ethylene and polar monomers is carried out in a closed stirred reactor containing an inert organic solvent at a pressure of 0.1-10 MPa and a reaction temperature of 50-150℃. The molar ratio of ethylene to the polar monomer is 2-12:1; The concentration of the nickel phosphonate catalyst in the solvent is 0.1-1 mmol / L.

8. The preparation method according to claim 7, characterized in that, The inert organic solvent is selected from one or more of aromatic hydrocarbons, alkanes, and halogenated hydrocarbons.

9. A polar-modified high-purity polyethylene, characterized in that, The polyethylene is prepared by the preparation method according to any one of claims 1-8, wherein the weight-average molecular weight is 900,000-1,100,000 and the insertion rate of polar monomers is 3-7 mol.

10. The application of the polar modified high-purity polyethylene according to claim 9 in the preparation of engineering plastics, fiber materials, high-barrier materials or functional coatings.

Images