High-performance uhmwpe and preparation process therefor by means of slurry method

Abstract

The present invention relates to the technical field of polyethylene, and in particular relates to a high-performance UHMWPE and a preparation process therefor by means of a slurry method. The process comprises using monomeric ethylene as a raw material, adding a catalyst to a solvent, and performing a polymerization reaction at a temperature of 60-100°C and a pressure of 0.1-10 MPa; and after the reaction is finished, performing a post-treatment to obtain a UHMWPE product, wherein regarding the catalyst used, a late transition metal catalyst using a 1,10-phenanthroline-5,6-dione as a skeleton is used as a main catalyst. In the present invention, the high activity and thermal stability of a diimine late transition metal catalyst is used to prepare a bimodal UHMWPE by means of a single-step reaction, thereby improving the processability of the product.

Description

A high-performance UHMWPE and its slurry preparation process Technical Field

[0001] This invention relates to the field of polyethylene technology, specifically to a high-performance UHMWPE and its slurry preparation process. Background Technology

[0002] Ultra-high molecular weight polyethylene (UHMWPE) possesses extremely high wear resistance and self-lubricating properties, making it highly popular in industrial applications such as conveyors, gears, and guide rails. Secondly, UHMWPE exhibits excellent impact resistance, which also makes it widely used in the defense industry. Furthermore, UHMWPE demonstrates good chemical resistance and low-temperature resistance, making it widely applicable in aerospace, marine engineering, petrochemicals, and new energy materials. Currently, the industry structure suffers from overcapacity in low- and mid-range products while facing a severe shortage of high-end products. Therefore, it is crucial to address several key issues in the manufacturing process of UHMWPE to propel it towards the high-end market. Polymerization is the core of UHMWPE production, and the choice of catalyst plays a decisive role in the final performance of UHMWPE. Researchers have made significant efforts in this area and achieved some progress. Currently, Zn (Ziegler-Natta) catalysts and metallocene catalysts are the two main types of catalysts. Zinc (Zn) catalysts have become the mainstream choice due to their wide range of industrial applications, but their multi-active-site characteristics result in poor microstructure consistency in polyethylene products, making it difficult to meet the increasingly stringent requirements of the high-end market. To address this issue, researchers have developed metallocene catalysts, which improve product consistency through a single active site. However, the synthesis process of metallocene catalysts is relatively complex, which to some extent limits their application in the polyethylene industry.

[0003] Given the shortcomings of Zn and metallocene catalysts, researchers have further developed metal complex olefin catalysts with iron, cobalt, nickel, palladium, and other post-transition metal atoms as the core. These catalysts exhibit lower sensitivity to oxygen and moisture and demonstrate high activity in olefin polymerization through structural modulation. Compared to Zn and metallocene catalysts, post-transition metal catalysts offer advantages such as higher stability, lower production costs, and the ability to produce novel polyolefin products with polar groups. The synthesis of post-transition metal catalysts is relatively simple, with high yields and significantly lower costs than Zn and metallocene catalysts, showing great industrial potential. However, the main obstacles hindering the industrial application of post-transition metal catalysts are catalytic activity and thermal stability. Since ethylene polymerization is an exothermic reaction, most post-transition metal catalysts struggle to withstand temperatures above 80°C, and their catalytic activity decreases at high temperatures. Chinese patent CN102775448B discloses a method for preparing post-transition metal complexes and polyethylene, but the reaction can only be carried out at relatively low temperatures (≤60°C) and only yields low molecular weight polyethylene (molecular weight less than 2400).

[0004] α-Diimine-type post-transition metal catalysts may be an effective strategy for addressing the aforementioned problems. α-Diimine catalysts were discovered by Brookhart in 1995: the α-diimine Ni / Pd catalyst structure inhibits the β-H elimination chain transfer reaction in olefin polymerization by increasing steric hindrance, yielding high molecular weight polyethylene (Single Strand Targeted Triplex Formation: Parallel-Stranded DNA Hairpin Duplexes for Targeting Pyrimidine Strands JACS., 1995, 117, 6416). Researchers have improved catalytic activity and thermal stability by constructing rigid cyclic α-diimine structures with certain steric hindrance. Inspired by this, researchers have mainly focused on improving the thermal stability by enhancing the rigidity of the ligand structure and steric hindrance. For example, Chinese patent CN110092744A discloses a high thermal stability transition metal complex containing tert-butyl asymmetric diimine pyridine for preparing polyethylene wax. It has a single catalytic active center, high catalytic activity and good thermal stability. However, it requires a large amount of co-catalyst (Al / Fe≥1000) and is used to prepare polyethylene wax with low molecular weight.

[0005] In addition, due to the high molecular weight of UHMWPE, it faces many difficulties in subsequent processing using extrusion, granulation, stretching and other processes. Bimodal polyethylene has both excellent mechanical properties and excellent processing performance. Its high molecular weight part is used to ensure its physical and mechanical strength, while the low molecular weight part plays a lubricating role in the resin, which can improve the processing performance of the product. At present, the main processes for producing bimodal polyethylene include: (1) melt mixing method, that is, producing resins of different molecular weights separately and then mixing them, which has the problems of high cost and uneven product quality. (2) segmented reaction method, that is, using series reactors to control different conditions to generate bimodal polyethylene with different molecular weights, which is flexible in operation and has a large range of grade adjustment, but the cost is high. (3) obtaining bimodal polyethylene directly through a single-stage reaction method, that is, obtaining bimodal polyethylene directly by using a catalyst during polymerization, such as mixing different catalysts or using a catalytic system with multiple catalytic active sites, which is a more ideal method.

[0006] Patent document CN104059184B uses a metallocene system to prepare bimodal polyethylene with tunable molecular weight distribution, mainly by adjusting the concentration and addition time of the co-catalyst alkylaluminum. Patent document CN105440184B uses a two-component composite catalytic system to prepare bimodal polyethylene through olefin catalytic slurry polymerization in two series-connected reactors. Patent document CN116640243A discloses a one-pot synthesis of bimodal polyethylene, in which two active centers are generated in situ during polymerization by utilizing the retention and removal of H atoms. Patent document CN117986424B uses a dual-center metallocene catalyst to prepare branched bimodal polyethylene, with catalysts including chromium-containing metals, zirconium-containing metals, and modified silicon-based supports. Patent document WO2023076208A1 discloses a method for preparing bimodal polyethylene using a bimodal catalyst system and a trimming solution in a reactor, employing metallocene compounds or non-metallocene catalysts. In summary, further research is needed on novel preparation processes for high-performance UHMWPE. Summary of the Invention

[0007] The purpose of this invention is to provide a high-performance UHMWPE and its slurry preparation process in order to solve the above-mentioned problems.

[0008] The objective of this invention is achieved through the following technical solution:

[0009] A high-performance UHMWPE slurry preparation process is described, which uses ethylene monomer as raw material, adds a catalyst to a solvent, and carries out a polymerization reaction under the conditions of 60-100℃ and 0.1-10MPa. After the reaction is completed, post-treatment is carried out to obtain UHMWPE product.

[0010] The catalyst is a post-transition metal catalyst with 1,10-phenanthroline-5,6-dione as its framework, which serves as the main catalyst.

[0011] The solvent is an inert organic solvent, including at least one of chain alkanes, cycloalkanes, and benzene aromatic derivatives with a boiling point not exceeding 120°C;

[0012] The post-processing includes: liquid-solid separation of the reaction slurry and drying of the product.

[0013] Furthermore, the post-transition metal catalyst is a nickel metal catalyst having the general structure shown in Formula C:

[0014] Where X is chlorine or bromine;

[0015] R1-R6 are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C 12 Aryl.

[0016] Preferably, at least one of R1-R3 is selected from C1-C6 alkyl, C1-C6 alkoxy or phenyl; and / or at least one of R4-R6 is selected from C1-C6 alkyl, C1-C6 alkoxy or phenyl.

[0017] More preferably, at least one of R1-R2 is selected from C1-C6 alkyl, C1-C6 alkoxy, C6-C 12 Phenyl; at least one of R3-R4 is selected from C1-C3 alkyl, C1-C3 alkoxy; and / or at least one of R5-R6 is selected from C1-C6 alkyl, C1-C6 alkoxy or phenyl.

[0018] Preferably, at least one of R1 and R3 is a C1-C4 alkyl or phenyl; and / or at least one of R4-R6 is a C1-C4 alkyl.

[0019] The post-transition metal catalyst used in this invention has bimetallic active sites with different chemical environments and a rigid parent ring framework structure. When used in the slurry method to prepare UHMWPE, it maintains high catalytic activity and high thermal stability, and can prepare bimodal UHMWPE.

[0020] In a preferred embodiment of the present invention, the post-transition metal catalyst is selected from any one of the following formulas:

[0021] Furthermore, the post-transition metal catalyst is a coordination compound formed by a diimine ligand with the structure shown in Formula L and a nickel salt, and the specific reaction formula is as follows:

[0022] Specifically, the following method can be used: the diimine ligand and nickel salt are dissolved in an anhydrous aprotic organic solvent at a molar ratio of 1:3-4, and the mixture is reacted in an anhydrous and oxygen-free environment to obtain the product.

[0023] Furthermore, the above-mentioned nickel metal catalyst was prepared by the following method: the ligand L prepared above was dissolved in an anhydrous aprotic organic solvent (e.g., acetonitrile, toluene) at a molar ratio of 1:3 to 4, and the reaction was carried out in an anhydrous and oxygen-free environment at a reaction temperature of 40 to 100°C for 12 to 36 hours. After the reaction was completed, the sample was filtered, washed 2 to 3 times with distilled water, and then dried in a vacuum drying oven.

[0024] Furthermore, the diimine ligand having the general structure shown in Formula L:

[0025] Wherein, R1-R6 can be the same or different groups, and R1-R6 are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C6 alkyl ... 12 Aryl.

[0026] The C1-C6 alkyl group includes straight-chain or branched alkyl groups, such as, but not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, or hexyl, with methyl, isopropyl, and tert-butyl being preferred.

[0027] The C1-C6 alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, pentoxy, or hexoxy.

[0028] 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.

[0029] As a preferred technical solution, at least one of R1-R2 is selected from C1-C6 alkyl, C1-C6 alkoxy or phenyl; at least one of R3-R4 is selected from C1-C3 alkyl, C1-C3 alkoxy; and / or, at least one of R5-R6 is selected from C1-C6 alkyl, C1-C6 alkoxy or phenyl, and the remainder is H.

[0030] As a preferred technical solution, at least one of R1 and R3 is a C1-C4 alkyl or phenyl, such as methyl, ethyl, n-propyl, isopropyl, tert-butyl, etc. or phenyl; and / or, at least one of R4-R6 is a C1-C4 alkyl, such as methyl, ethyl, n-propyl, isopropyl, tert-butyl, etc., and the rest are H.

[0031] In a preferred embodiment of the present invention, the diimine ligand is selected from any one of the following diimine ligand compounds:

[0032] The diimine ligands of Formula L of this invention have an o-phenanthroline skeleton. On the one hand, the 1,10-phenanthroline skeleton has a certain rigidity, which can provide steric hindrance and prevent the post-transition metal catalyst from deactivating at high temperatures. On the other hand, the 1,10-phenanthroline skeleton has two N atoms, and the different electronegativity of N atoms and C atoms helps to improve the electronic effect of the catalyst. In addition, after reacting with amines and metal coordination, the 1,10-phenanthroline-5,6-dione skeleton can form two active sites. The chemical environments between the two active sites are completely different, which can produce bimodal ultra-high molecular weight polyethylene.

[0033] The above-mentioned method for preparing diimine ligands involves using a 1,10-phenanthroline-5,6-dione derivative with the general structure shown in Formula I and an aniline derivative with the general structure shown in Formula II as raw materials to prepare the diimine ligands via acid catalysis. The specific reaction formula is as follows:

[0034] In the 1,10-phenanthroline-5,6-dione derivative of the general formula shown in Formula I, R1-R2 can be the same or different groups, independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, aromatic phenyl, aromatic naphthyl, aromatic biphenyl, etc.; R3 can be the same or different groups, independently selected from H, C1-C3, C1-C3 alkoxy, etc. Preferably, a 1,10-phenanthroline derivative with an electron-donating effect is used as the vicinal dicarbonyl raw material, and more preferably, 1,10-phenanthroline with electron-donating groups on R1 and R3 is used as the vicinal dicarbonyl raw material. More preferably, 1,10-phenanthroline with sterically hindered electron-donating groups on R1 and R3 is used as the vicinal dicarbonyl raw material. More preferably, 1,10-phenanthroline with R1 being methyl, isopropyl, or phenyl and R3 being methyl is used as the vicinal dicarbonyl raw material.

[0035] In embodiments of the present invention, the 1,10-phenanthroline-5,6-dione derivative may be selected from 1,10-phenanthroline-5,6-dione, 2,9-dimethyl-1,10-phenanthroline-5,6-dione, 2,9-diphenyl-1,10-phenanthroline-5,6-dione, 2,9-diisopropyl-1,10-phenanthroline-5,6-dione, 4,7-dimethyl-1,10-phenanthroline-5,6-dione, 2,9-diphenyl-1,10-phenanthroline-5,6-dione, 2,9-diphenyl-1,10-phenanthroline-5,6-dione, 2,9-diphenyl-1,10-phenanthroline-5,6-dione, 2,9-diphenyl-1,10-phenanthroline-5,6-dione, 2,9-diphenyl-1,10-phenanthroline-5,6-dione, etc.

[0036] The aniline derivatives of the general formula II have a primary amine as the main skeleton, and R4 can be the same or different H, C1-C6 alkyl, C1-C6 alkoxy, etc. Preferably, a primary amine with an electron-donating effect is used as the amine raw material, and more preferably, a primary amine with an electron-donating group having a certain steric hindrance effect is used as the amine raw material. Methylamine, aniline, 3,5-dimethylaniline, and p-methylaniline are further preferred as amine raw materials.

[0037] In this embodiment of the invention, the aniline derivative is selected from aniline, o-methylaniline, 3,5-dimethylaniline, p-methylaniline, etc.

[0038] As a preferred technical solution, the preparation method of the diimine ligand of the present invention includes the following steps: a 1,10-phenanthroline-5,6-dione derivative and an aniline derivative are dissolved in an aprotic polar organic solvent at a molar ratio of 1:2 to 2.5, and then reacted at 40 to 150°C using a non-oxidizing strong organic acid as a catalyst (catalytic level). After the reaction is completed, the solvent is removed from the mixture and it is purified to obtain the diimine ligand.

[0039] 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. The reaction temperature is preferably 60-100℃, and the reaction time is generally between 12-36 hours. The solvent can be removed using conventional methods in the art, such as rotary evaporation. The product can be purified using conventional methods in the art, such as recrystallization or column chromatography.

[0040] The inventors discovered that the post-transition metal catalyst with the novel structure described above unexpectedly exhibits high catalytic activity over a wide temperature range, particularly excellent high-temperature stability. For example, at a reaction temperature of 80°C, the catalyst exhibits a high activity of 7.88 × 10⁻⁶. 6 The exact mechanism behind the catalytic activity of g / mol·h is not fully understood, but it is speculated that the post-transition metal catalyst with a 1,10-phenanthroline-5,6-dione framework exhibits higher rigidity and superior electronic effects compared to the traditional 1,2-dione structure, preventing deactivation at high temperatures. Unlike phenanthrene, the 1,10-phenanthroline framework contains two nitrogen atoms in its ring; the difference in electronegativity between nitrogen and carbon atoms also contributes to improved catalytic electronic effects. Furthermore, the 1,10-phenanthroline-5,6-dione framework, after reaction with amines and metal coordination, can form two active sites with completely different chemical environments, enabling the production of bimodal ultra-high molecular weight polyethylene.

[0041] The post-transition metal catalyst, with the aid of a co-catalyst, yields bimodal ultra-high molecular weight polyethylene at lower pressure and with higher catalytic activity.

[0042] Furthermore, the solvent is preferably a benzene-based aromatic derivative or alkane that is liquid at room temperature, has low viscosity, a boiling point not exceeding 110°C, and low solubility in ultra-high molecular weight polyethylene, such as toluene, xylene, chlorobenzene, or hexane.

[0043] Furthermore, the catalyst further includes a co-catalyst, which is selected from at least one of alkylaluminoxane, alkylaluminum, and aromatic boron. More preferably, the selected co-catalyst is mainly alkylaluminoxane, and more preferably methylaluminoxane, modified methylaluminoxane, or isobutylaluminoxane as co-catalyst. The molar ratio of the post-transition metal catalyst to the co-catalyst is 1:200 to 500.

[0044] Furthermore, when producing ultra-high molecular weight polyethylene, the polymerization temperature is 70-90℃, and the pressure inside the reactor is controlled by ethylene gas at a pressure of 0.1-2 MPa, preferably 0.1-1 MPa.

[0045] Compared with the prior art, the present invention has the following innovative features:

[0046] This invention utilizes a novel diimine-based post-transition metal catalyst as the main catalyst in the slurry method for preparing UHMWPE. This catalyst possesses bimetallic active sites with different chemical environments and a rigid parent ring framework structure. It uses 1,10-phenanthroline-5,6-dione as its framework, and the presence of the phenanthroline ring structure provides a degree of rigidity, enhancing catalytic activity and thermal stability. Furthermore, the 1,10-phenanthroline-5,6-dione contains two pyridine rings. These pyridine rings exhibit significantly different electronic effects from the benzene ring, and the lone pair electrons on the nitrogen atom can conjugate with the benzene ring and the diimine structure, further optimizing the catalyst's electronic structure. This allows for the production of two metal active centers with completely different chemical environments, enabling the one-step preparation of bimodal UHMWPE. The product exhibits good processing performance, with a weight-average molecular weight distribution of 1.5 to 2 million and a PDI of 5 to 6, demonstrating excellent performance. Attached Figure Description

[0047] Figure 1 shows the molecular weight distribution of polyethylene sample E8. Detailed Implementation

[0048] The present invention will now be described in detail. Any technical solutions not described in detail herein are those already disclosed in the art.

[0049] The specific sources of the main reagents used in each embodiment are as follows:

[0050] 1,10-Phenanthroline-5,6-dione (CAS: 27318-90-7, Sigma-Aldrich)

[0051] 2,9-Dimethyl-1,10-phenanthroline-5,6-dione (CAS: 102331-54-4, Henan Weitixi Chemical Co., Ltd.)

[0052] 2,9-Diphenyl-1,10-phenanthroline-5,6-dione (CAS: 1654020-68-4, Henan Lien Chemical)

[0053] 2,9-Diisopropyl-1,10-phenanthroline-5,6-dione (CAS: 1243254-92-3, Henan Lien Chemical Co., Ltd.)

[0054] 4,7-Dimethyl-1,10-phenanthroline (CAS: 3248-05-3, Leyan Reagent)

[0055] 4,7-Dimethyl-1,10-phenanthroline-5,6-dione (CAS: 1713236-32-8, synthesized)

[0056] 2,3-Butanedione (CAS: 431-03-8, Sigma-Aldrich)

[0057] 2,6-Diacetylpyridine (CAS: 1129-30-2, Sigma-Aldrich)

[0058] Salicylaldehyde (CAS: 90-02-8, Sigma-Aldrich)

[0059] Methylaluminoxane (CAS: 120144-90-3, Jiuding Chemical)

[0060] High-purity ethylene (CAS: 74-85-1, Shanghai Liquid Air Gas)

[0061] Aniline (CAS: 62-53-3, Sigma-Aldrich)

[0062] o-Toluidine (CAS: 95-53-4, Sigma-Aldrich)

[0063] 3,5-Dimethylaniline (CAS: 108-69-0, Sigma-Aldrich)

[0064] p-Toluidine (CAS: 106-49-0, Sigma-Alrich)

[0065] p-Bromoaniline (CAS: 106-40-1, Sigma-Aldrich)

[0066] p-Toluenesulfonic acid (CAS: 6192-52-5, Sigma-Aldrich)

[0067] Acetic acid (CAS: 64-19-7, Sigma-Aldrich)

[0068] Ethanol (CAS: 64-17-5, Sigma-Aldrich)

[0069] Dichloromethane (CAS: 75-09-2, Sigma-Aldrich)

[0070] Benzene (CAS: 71-43-2, Sigma-Aldrich)

[0071] Toluene (CAS: 108-88-3, Sigma-Aldrich)

[0072] 98% concentrated sulfuric acid (CAS: 76664-93-9, Sigma-Aldrich)

[0073] Nitric acid (CAS: 7697-37-2, Sigma-Aldrich)

[0074] Sodium hydroxide (CAS: 1310-73-2, Sigma-Aldrich)

[0075] Hydrochloric acid (CAS: 7647-01-0, Sigma-Aldrich)

[0076] Acetonitrile (CAS: 75-05-8, Sigma-Aldrich)

[0077] Methanol (CAS: 67-56-1, Sigma-Aldrich)

[0078] Unless otherwise specified, all solvents used in the examples must be anhydrous.

[0079] Preliminary Example 1

[0080] Catalyst sample 1 was prepared according to the following steps:

[0081] (1) The specific synthesis method of ligand L1 is as follows:

[0082] 2.10 g of 1,10-phenanthroline-5,6-dione (10 mmol) was added to a 250 mL three-necked flask, dissolved in approximately 100 mL of benzene, followed by the addition of 2.14 g of aniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol). The three-necked flask was heated to 65 °C using a condenser equipped with a water separator, and the reaction was carried out for 24 h. After the reaction was completed, the solvent was removed by vacuum distillation, and the product was then purified by recrystallization from ethanol. The purified product was dried to obtain ligand L1, with a final yield of 90%. 1 H 300MHz, DMSO): 9.12-7.11 (m, 16H, Ar-H). C 24 H 16 N4: Calculated values ​​(%) by elemental analysis: C, 79.98; H, 4.47; N, 15.55. Experimental values ​​(%): C, 80.11; H, 4.55; N, 15.41.

[0083] (2) Preparation of catalyst sample 1: The obtained ligand L1 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L1 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 1.

[0084] Preliminary Example 2

[0085] Catalyst sample 2 was prepared according to the following steps:

[0086] (1) The specific synthesis method of ligand L2 is as follows:

[0087] 2.38 g (10 mmol) of 2,9-dimethyl-1,10-phenanthroline-5,6-dione was added to a 250 mL three-necked flask and dissolved in approximately 100 mL of anhydrous acetic acid. Then, 2.14 g of aniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol) were added. The three-necked flask was heated to 100 °C using a condenser equipped with a water separator, and the reaction was carried out for 24 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The product was then recrystallized from ethanol to obtain ligand L2, with a final yield of 85%. 1 H 300MHz, DMSO): 8.84-7.30 (m, 14H, Ar-H); 2.95 (d, 6H, -CH3). C 26 H 20N4: Calculated elemental analysis (%): C, 80.39; H, 5.19; N, 14.42. Experimental measured values ​​(%): C, 80.66; H, 5.29; N, 14.07.

[0088] (2) Preparation of catalyst sample 2: The obtained ligand L2 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L2 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 2.

[0089] Preliminary Example 3

[0090] Catalyst sample 3 was prepared according to the following steps:

[0091] (1) The specific synthesis method of ligand L3 is as follows:

[0092] 3.68 g of 2,9-dibromo-1,10-phenanthroline-5,6-dione (10 mmol) was added to a 250 mL three-necked flask and dissolved in approximately 100 mL of anhydrous acetic acid. Then, 2.14 g of aniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol) were added. The three-necked flask was heated to 100 °C using a condenser equipped with a water separator, and the reaction was carried out for 24 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The product was then recrystallized from ethanol to obtain ligand L3, with a final yield of 71%. 1 H 300MHz, DMSO): 9.14-7.22 (m, 14H, Ar-H). C 24 H 14 N4Br2: Elemental analysis calculated values ​​(%): C, 55.63; H, 2.72; N, 10.81; Br, 30.84. Experimental measured values ​​(%): C, 55.77; H, 2.85; N, 10.71; Br, 30.73.

[0093] (2) Preparation of catalyst sample 3: The obtained ligand L3 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L3 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 3.

[0094] Preliminary Example 4

[0095] Catalyst sample 4 was prepared following these steps:

[0096] (1) The specific synthesis method of ligand L4 is as follows:

[0097] 3.62 g of 2,9-diphenyl-1,10-phenanthroline-5,6-dione (10 mmol) was added to a 250 mL three-necked flask and dissolved in approximately 100 mL of anhydrous acetic acid. Then, 2.14 g of aniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol) were added. The three-necked flask was heated to 100 °C using a condenser equipped with a water separator, and the reaction was carried out for 24 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The product was then recrystallized from ethanol to obtain ligand L4, with a final yield of 88%. 1 H 300MHz, DMSO): 9.33-7.42 (m, 24H, Ar-H). C 36 H 24 N4: Elemental analysis calculated values ​​(%): C, 84.35; H, 4.72; N, 10.92. Experimental measured values ​​(%): C, 84.69; H, 4.82; N, 10.57.

[0098] (2) Preparation of catalyst sample 4: The obtained ligand L4 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L4 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 4.

[0099] Preliminary Example 5

[0100] Catalyst sample 5 was prepared according to the following steps:

[0101] (1) The specific synthesis method of ligand L5 is as follows:

[0102] 2.94 g of 2,9-diisopropyl-1,10-phenanthroline-5,6-dione (10 mmol) was added to a 250 mL three-necked flask and dissolved in 100 mL of anhydrous acetic acid. Then, 2.14 g of aniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol) were added. The three-necked flask was heated to 100 °C and reacted for 24 h using a condenser equipped with a water separator. After the reaction was complete, the solvent was removed by distillation under reduced pressure. The product was then recrystallized from ethanol to obtain ligand L5, with a final yield of 91%. 1H 300MHz, DMSO): 8.79-7.52(m,14H,Ar-H); 3.95-1.77(m,14H,-CH(CH3)2). C 30 H 28 N4: Calculated values ​​(%) by elemental analysis: C, 80.39; H, 6.35; N, 12.60. Experimental values ​​(%): C, 80.87; H, 6.43; N, 12.07.

[0103] (2) Preparation of catalyst sample 5: The obtained ligand L5 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L5 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 5.

[0104] Preliminary Example 6

[0105] Catalyst sample 6 was prepared according to the following steps:

[0106] (1) The specific synthesis method of ligand L6 is as follows:

[0107] First, 4,7-dimethyl-1,10-phenanthroline-5,6-dione was synthesized: 1.35 g (6.5 mmol) of 4,7-dimethyl-1,10-phenanthroline and 7.5 g of potassium bromide were mixed, and sulfuric acid (30 ml) was added dropwise over 15 minutes at 0 °C, followed by nitric acid (15 ml, added dropwise over 15 minutes). The resulting mixture was heated at 80 °C for 4 hours, and the solution was cooled to 0 °C after the reaction was complete. The cold acidic mixture was poured onto ice. Under vigorous stirring, a 5% NaOH solution was added to the reaction mixture to adjust the pH to 3. The mixture was extracted with dichloromethane (3 × 300 ml), the organic phase was dried with MgSO4, the solvent was evaporated, and the resulting solid was dried under vacuum for later use.

[0108] 2.38 g of 4,7-dimethyl-1,10-phenanthroline-5,6-dione (10 mmol) was added to a 250 mL three-necked flask and dissolved in approximately 100 mL of anhydrous acetic acid. Then, 2.14 g of aniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol) were added. The flask was heated to 100 °C using a condenser equipped with a water separator, and the reaction was carried out for 24 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The product was then recrystallized from ethanol to obtain ligand L6, with a final yield of 75%. 1H 300MHz, DMSO): 9.14-7.25(m,14H,Ar-H); 3.12-2.56(m,6H,-CH3). C 26 H 20 N4: Calculated values ​​(%) by elemental analysis: C, 80.39; H, 5.19; N, 14.42. Experimental values ​​(%): C, 80.42; H, 5.21; N, 14.37.

[0109] (2) Preparation of catalyst sample 6: The obtained ligand L6 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L6 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 6.

[0110] Preliminary Example 7

[0111] Catalyst sample 7 was prepared according to the following steps:

[0112] (1) The specific synthesis method of ligand L7 is as follows:

[0113] 3.62 g of 2,9-diphenyl-1,10-phenanthroline-5,6-dione (10 mmol) was added to a 250 mL three-necked flask and dissolved in approximately 100 mL of anhydrous acetic acid. Then, 2.46 g of o-methylaniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol) were added. The flask was heated to 100 °C using a condenser equipped with a water separator, and the reaction was carried out for 24 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The product was then recrystallized from ethanol to obtain ligand L7, with a final yield of 68%. 1 H 300MHz, DMSO): 8.52-7.49 (m, 22H, Ar-H); 2.50 (s, 6H, -CH3). C 38 H 28 N4: Elemental analysis calculated values ​​(%): C, 84.42; H, 5.22; N, 10.36. Experimental measured values ​​(%): C, 84.45; H, 5.26; N, 10.33.

[0114] (2) Preparation of catalyst sample 7: The obtained ligand L7 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L7 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 7.

[0115] Preliminary Example 8

[0116] Catalyst sample 8 was prepared according to the following steps:

[0117] (1) The specific synthesis method of ligand L8 is as follows:

[0118] 3.62 g of 2,9-diphenyl-1,10-phenanthroline-5,6-dione (10 mmol) was added to a 250 mL three-necked flask and dissolved in approximately 100 mL of anhydrous acetic acid. Then, 2.78 g of 3,5-dimethylaniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol) were added. The three-necked flask was heated to 100 °C and reacted for 24 h using a condenser equipped with a water separator. After the reaction was complete, the solvent was removed by distillation under reduced pressure. The product was then recrystallized from ethanol to obtain ligand L8, with a final yield of 68%. 1 H 300MHz, DMSO): 9.05-7.16 (m, 20H, Ar-H); 2.82-1.80 (m, 12H, -CH3). C 40 H 32 N4: Elemental analysis calculated values ​​(%): C, 84.48; H, 5.67; N, 9.85. Experimental measured values ​​(%): C, 84.51; H, 5.72; N, 9.77.

[0119] (2) Preparation of catalyst sample 8: The obtained ligand L8 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L8 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 8.

[0120] Preliminary Example 9

[0121] Catalyst sample 9 was prepared according to the following steps:

[0122] (1) The specific synthesis method of ligand L9 is as follows:

[0123] 3.62 g of 2,9-diphenyl-1,10-phenanthroline-5,6-dione (10 mmol) was added to a 250 mL three-necked flask and dissolved in approximately 100 mL of anhydrous acetic acid. Then, 2.46 g of p-methylaniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol) were added. The three-necked flask was heated to 100 °C and reacted for 24 h using a condenser equipped with a water separator. After the reaction was complete, the solvent was removed by distillation under reduced pressure. The product was then recrystallized from ethanol to obtain ligand L9, with a final yield of 84%. 1 H 300MHz, DMSO): 8.99-7.58 (m, 22H, Ar-H); 2.91-1.77 (m, 6H, -CH3). C 38 H 28 N4: Elemental analysis calculated values ​​(%): C, 84.42; H, 5.22; N, 10.36. Experimental measured values ​​(%): C, 84.55; H, 5.33; N, 10.30.

[0124] (2) Preparation of catalyst sample 9: The obtained ligand L9 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L9 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 9.

[0125] Preliminary Example 10

[0126] Catalyst sample 10 was prepared according to the following steps:

[0127] (1) The specific synthesis method of ligand L10 is as follows:

[0128] 3.62 g of 2,9-diphenyl-1,10-phenanthroline-5,6-dione (10 mmol) was added to a 250 mL three-necked flask and dissolved in approximately 100 mL of anhydrous acetic acid. Then, 3.95 g of p-bromoaniline (23 mmol) and 7 μL of p-toluenesulfonic acid (approximately 50 μmol) were added. The three-necked flask was heated to 100 °C and reacted for 24 h using a condenser equipped with a water separator. After the reaction was complete, the solvent was removed by distillation under reduced pressure. The product was then recrystallized from ethanol to obtain ligand L10, with a final yield of 73%. 1 H 300MHz, DMSO): 9.23-7.67 (m, 22H, Ar-H). C 36 H 22N4Br2: Elemental analysis calculated values ​​(%): C, 64.50; H, 3.31; N, 8.36; Br, 23.84. Experimental measured values ​​(%): C, 64.62; H, 3.33; N, 8.44; Br, 23.79.

[0129] (2) Preparation of catalyst sample 10: The obtained ligand L10 was coordinated with NiCl2. The specific steps were as follows: Under anhydrous and oxygen-free conditions, about 100 ml of ultra-dry acetonitrile was added to a three-necked flask, along with ligand L10 (8.4 mmol) and anhydrous NiCl2 (4 mmol). The reaction temperature was controlled at 55 °C and the reaction time was 24 hours. After the reaction was completed, the mixture was cooled to room temperature, concentrated by evaporation, filtered out the solvent, washed several times with dry n-hexane, and dried to obtain catalyst sample 10.

[0130] The catalysts and raw materials for each of the preliminary examples 1 to 10 are detailed in Table 1.

[0131] Table 1 Catalysts and their raw materials in the preliminary examples

[0132] The present invention also provides the following comparative examples.

[0133] Comparative Example 1

[0134] Prepare catalyst sample a according to the following steps.

[0135] (1) Synthesis of pyridine diimine ligand:

[0136] 0.82 g of 2,6-diacetylpyridine (5 mmol) and 1.65 g of 4-amino-3,5-dimethylphenol (12 mmol) were dissolved in 150 ml of methanol. 1 ml of formic acid was added and the mixture was refluxed at 80 °C for 12 hours. After the reaction was completed, the solvent was evaporated and concentrated, and the mixture was recrystallized by adding n-hexane to obtain ligand L.

[0137] (2) Preparation of catalyst sample a:

[0138] Under nitrogen atmosphere, 1 mmol of ligand L was dissolved in 30 mL of THF and reacted for 1 hour. FeCl2 was then added, and the reaction continued for 6 hours. THF was removed by rotary evaporation to obtain catalyst a. The final yield was 85%. 1 H 300MHz, DMSO): 9.27(s,2H,-OH); 8.72-7.04(m,7H,-Ar-H); 2.68-2.11(m,18H,-CH3). C 25 H 27N3O2: Elemental analysis calculated values ​​(%): C, 74.79; H, 6.78; N, 10.47; O, 7.97. Experimental measured values ​​(%): C, 74.78; H, 6.73; N, 10.54; O, 8.02.

[0139] Comparative Example 2

[0140] Catalyst sample b: Commercially available metallocene catalyst dichlorotitanene (CAS: 1271-19-8), its structural formula is as follows:

[0141] Example

[0142] The above-mentioned catalysts were used as main catalysts to prepare polyethylene via slurry polymerization, and the catalyst performance was tested. The specific steps are as follows:

[0143] A 250 ml stainless steel reactor (with a cooling jacket) was vacuum heated at 150 °C for approximately 30 min, then cooled to ambient temperature. The reactor was pressurized to 2 atm with ethylene, vented, and then pressurized again with ethylene. This process was repeated three times to ensure the reactor was filled with an ethylene atmosphere. The co-catalyst MAO (0.5 mmol) was dissolved in approximately 100 ml of dry hexane and injected into the reactor. The reactor was continuously stirred for 5 min under an ethylene pressure of 1.2 atm. Finally, 50 ml of the catalyst-hexane dilution (containing approximately 2 μmol of catalyst) was added to the reactor using a syringe and stirred thoroughly. Gaseous ethylene was continuously added throughout the reaction, maintaining the ethylene pressure inside the reactor at 9–10 atm. The polymerization temperature was controlled at 60–100 °C, and the polymerization process was completed after 2 h. Post-treatment was then performed by adding acidic methanol (95:5 ethanol / hydrochloric acid by mass) to inactivate the catalyst. The resulting precipitated polymer was collected, separated by rotary evaporation, and dried under vacuum at 40 °C to a fixed weight to obtain a polyethylene sample, which was then weighed and analyzed.

[0144] The catalyst activity was calculated based on the yield of the polyethylene sample, expressed as g polyethylene / (mol catalyst × h). Table 2 lists the catalytic activity of each catalyst at different temperatures.

[0145] Table 2 Catalytic activity of different catalysts at different temperatures (unit: 10⁻⁶) 6 g PE / mol cat h)

[0146] Note: "--" indicates that the action was not taken.

[0147] Table 2 shows that sample a, a catalyst obtained from pyridine diimine ligands (lacking the 1,10-phenanthroline-5,6-dione framework), exhibits poor thermal stability, with its catalytic activity significantly decreasing above 80℃. Sample b, a metallocene catalyst, dichlorotitanium chloride, shows good catalytic activity at 70–80℃, but its activity significantly decreases above 100℃. Compared to the comparative examples, except for samples 3 and 10, which use halogen substituents, the other catalyst samples demonstrate excellent thermal stability (especially when electron donation is affected by steric hindrance), maintaining excellent ethylene catalytic activity at temperatures between 80 and 100℃. This indicates that the post-transition metal catalysts obtained using 1,10-phenanthroline-5,6-dione as the diimine framework possess high catalytic activity and thermal stability. For example, sample 8 achieves a catalytic activity of 7.88 × 10⁻⁶ at 90℃. 6 The catalytic activity at 100℃ is 4.57 × 10⁻⁶ gPE / g cat h. 6 gPE / g cat h.

[0148] [Performance Testing of Polyethylene Samples]

[0149] Molecular weight was determined for a portion of the polyethylene samples obtained above: weight-average molecular weight (Mw) and number-average molecular weight (Mn) were determined by gel permeation chromatography according to GB / T 27843-2011 "Determination of Low Molecular Weight Components in Polymers of Chemicals - Gel Permeation Chromatography (GPC)"; the molecular weight distribution index (PDI) of polyethylene was determined by the ratio of the measured weight-average molecular weight to the number-average molecular weight; peak distribution was determined based on the GPC molecular weight distribution curve. Specific test results are shown in Table 3, and Figure 1 provides an example of the molecular weight distribution of polyethylene sample E8.

[0150] Table 3 Test results of polyethylene samples

[0151] As shown in Table 3, the present invention prepared bimodal ultra-high molecular weight polyethylene. Except for polyethylene samples E3 and E10 prepared by catalyst samples 3 and 10 with halogen substituents, the polyethylene of the present invention has a weight-average molecular weight distribution of 1.5 million to 2 million and a PDI of 5 to 6, all of which are bimodal polyethylenes, exhibiting superior processing performance. Comparative Example 1 only obtained low molecular weight polyethylene products, which were unimodal polyethylenes, while Comparative Example 2 prepared unimodal polyethylene.

[0152] 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 high-performance UHMWPE slurry preparation process, characterized in that, Using ethylene monomer as raw material, a catalyst is added to a solvent, and a polymerization reaction is carried out at a temperature of 60-100℃ and a pressure of 0.1-10MPa. After the polymerization reaction is completed, post-treatment is carried out to obtain UHMWPE product. The catalyst is a post-transition metal catalyst with 1,10-phenanthroline-5,6-dione as its framework, which serves as the main catalyst. The solvent is an inert organic solvent, including at least one of chain alkanes, cycloalkanes, and benzene aromatic derivatives with a boiling point not exceeding 120°C; The post-processing includes: liquid-solid separation of the reaction slurry and drying of the product.

2. The high-performance UHMWPE slurry preparation process according to claim 1, characterized in that, The post-transition metal catalyst is a nickel metal catalyst with the general structure shown in Formula C: Wherein, X is chlorine or bromine; R1-R6 are independently selected from H, C1-C6 alkyl, C1-C6 alkoxy, C6-C 12 Aryl.

3. The high-performance UHMWPE slurry preparation process according to claim 2, characterized in that, At least one of R1-R3 is selected from C1-C6 alkyl, C1-C6 alkoxy or phenyl; And / or, at least one of R4-R6 is selected from C1-C6 alkyl, C1-C6 alkoxy or phenyl.

4. The high-performance UHMWPE slurry preparation process according to claim 2, characterized in that, At least one of R1 and R3 is a C1-C4 alkyl or phenyl; And / or, at least one of R4-R6 is a C1-C4 alkyl group.

5. A high-performance UHMWPE slurry preparation process according to any one of claims 2-4, characterized in that, The post-transition metal catalyst is a coordination compound formed by a diimine ligand with a nickel salt, as shown in Formula L, and the specific reaction formula is as follows:

6. The high-performance UHMWPE slurry preparation process according to claim 1, characterized in that, The catalyst further includes a co-catalyst, which is selected from at least one of alkylaluminoxane, alkylaluminum, and aromatic boron; The molar ratio of the post-transition metal catalyst to the co-catalyst is 1:200 to 500.

7. The high-performance UHMWPE slurry preparation process according to claim 1, characterized in that, The polymerization temperature is 70-90℃, and the pressure inside the reactor is controlled by ethylene gas at a pressure of 0.1-2 MPa.

8. The high-performance UHMWPE slurry preparation process according to claim 7, characterized in that, The pressure is 0.1-1 MPa.

9. A UHMWPE obtained by the preparation process according to any one of claims 1 to 8, characterized in that, This UHMWPE is a bimodal polyethylene with a weight-average molecular weight distribution of 1.5 million to 2 million and a PDI of 5 to 6.

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