A method for preparing low-entanglement ultra-high molecular weight polyethylene

Abstract

The present invention provides the use of a binuclear rare earth compound in the preparation of polyethylene; the binuclear rare earth compound has a structure as shown in formula (I). The present invention also provides a method for preparing polyethylene. The present invention applies a binuclear rare earth compound with a specific structure in the polyethylene preparation process, thereby obtaining low-entanglement ultra-high molecular weight polyethylene. The present invention uses a catalyst composition composed of a rare earth compound and / or an organic boron salt and a main-group alkyl reagent having the general formula (I), which has very high catalytic activity for ethylene homopolymerization and can produce low-entanglement ultra-high molecular weight polyethylene in a wide temperature range and a wide ethylene pressure range. The method for preparing polyethylene provided by the present invention can produce low-entanglement ultra-high molecular weight polyethylene in a wide temperature range, a wide ethylene pressure range and a wide catalyst concentration range, and the preparation process is simple, the conditions are mild, and the controllability is strong, which is conducive to industrial application and commercial promotion.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-entanglement ultra-high molecular weight polyethylene preparation, and relates to the application of binuclear rare earth compounds in the preparation of polyethylene, a method for preparing a ligand of the binuclear rare earth compound, and a method for preparing polyethylene, and in particular to the application of binuclear rare earth compounds in the preparation of polyethylene, a method for preparing a ligand of the binuclear rare earth compound, and a method for preparing low-entanglement ultra-high molecular weight polyethylene. Background Art

[0002] Ultra-high molecular weight polyethylene (UHMWPE) is a semi-crystalline material with exceptional mechanical properties, high wear resistance, low friction coefficient, excellent chemical resistance, and a low dielectric constant. It is widely used in lithium battery separators, strong ropes, body armor, tissue engineering scaffolds, and artificial joints. However, its ultra-high molecular weight is a double-edged sword. While it provides excellent performance, it also results in extremely high melt viscosity and poor fluidity, making it virtually impossible to form using conventional methods such as extrusion, blown film, and injection molding, significantly limiting its expanded application. This is primarily due to the physical entanglement between the ultra-long polyethylene molecular chains. Reducing the degree of physical entanglement between UHMWPE chains, creating low-entanglement UHMWPE, can effectively lower its melt viscosity and improve its processing properties. Literature has demonstrated that low-entanglement UHMWPE exhibits excellent processing fluidity. It can be molded into translucent, high-strength films below its melt temperature.

[0003] Currently, low-entanglement UHMWPE is primarily produced by the following methods: Commercially available highly entangled UHMWPE is crystallized at low temperatures from a 10% decahydronaphthalene solution to produce low-entanglement UHMWPE. Ziegler-Natta catalysts can produce low-entanglement UHMWPE at low temperatures (-20°C), low catalyst concentrations, and low ethylene pressures (less than 1 bar). Single-site early transition metal catalysts can also produce low-entanglement UHMWPE at higher temperatures (less than 40°C), low catalyst concentrations, and low ethylene pressures (less than 4 bar). However, these low-entanglement UHMWPE production methods require demanding process conditions and low production efficiency, resulting in high costs for low-entanglement UHMWPE.

[0004] Therefore, how to find a more suitable way to prepare low-entanglement UHMWPE and overcome the above-mentioned problems of existing preparation methods has become one of the focuses of widespread attention of many cutting-edge researchers in the field. Summary of the Invention

[0005] In light of this, the present invention aims to address the technical problem of using a binuclear rare earth compound in the preparation of polyethylene, a method for preparing a ligand for the binuclear rare earth compound, and a method for preparing polyethylene, particularly a method for preparing low-entanglement ultrahigh molecular weight polyethylene. The present invention provides a catalytic system and preparation method capable of producing low-entanglement ultrahigh molecular weight polyethylene over a wide temperature range, ethylene pressure range, and catalyst concentration range. Furthermore, the preparation process is simple, the conditions are mild, and the controllability is strong, making it suitable for industrial application and commercialization.

[0006] The present invention provides the use of binuclear rare earth compounds in the preparation of polyethylene;

[0007] The binuclear rare earth compound has a structure as shown in formula (I):

[0008]

[0009] Among them, R 1 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted cycloalkyl group;

[0010] R is a silyl group, a substituted or unsubstituted aryl group;

[0011] M is a rare earth metal;

[0012] L is a Lewis base;

[0013] n is 0 or 1.

[0014] Preferably, the polyethylene is ultra-high molecular weight polyethylene;

[0015] The R 1Including phenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 4-trifluoromethoxyphenyl, 4-phenoxyphenyl, 4-methylthiophenyl, 4-phenylphenyl, 4-benzylphenyl, 4-tritylphenyl, 4-N'N-dimethylphenyl, 4-fluorophenyl, 4-bromophenyl, 4-chlorophenyl, 4-iodophenyl, 2,6-difluorophenyl, 3,4-difluorophenyl, 3,4,5-trifluorophenyl, 3-methylphenyl, 3-ethylphenyl, 3-isopropylphenyl, 3-trifluoromethylphenyl, 3-methoxyphenyl, 3-phenylphenyl, 3-fluorophenyl, 3-chlorophenyl, 3-bromophenyl, 2-methylphenyl, 2-ethylphenyl, 2-isopropylphenyl, 2-phenylaniline, 2-fluorophenyl, 2-chlorophenyl one or more of phenyl, 2-bromophenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylbenzene, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, 3,5-difluorophenyl, 3,5-trifluoromethylphenyl, 3,5-dimethylphenyl, 3,5-dimethoxyphenyl, 2,6-diethyl-4-methylphenyl, o-methoxyphenyl, o-methylthiophenyl, 2,6-diphenylphenyl, 4-methyl-2,6-dipentafluorophenylphenyl, 1-naphthyl, 2-naphthyl, cyclododecyl, cyclohexyl, p-tert-butylcyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl, cyclobutane, cyclopropyl, trans-4-methylcyclohexyl, cis-2-methylcyclohexyl, trans-2-methylcyclohexyl and 3-methylcyclohexyl;

[0016] Said R comprises one or more of trimethylsilyl, phenyldimethylsilyl, phenyl and 4-methylphenyl;

[0017] The binuclear rare earth compound is a binuclear rare earth compound chelated with a non-cyclopentadienyl ligand.

[0018] Preferably, the M comprises one or more of scandium, yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium;

[0019] The L comprises one or more of tetrahydrofuran, ethylene glycol dimethyl ether, tertiary amine, pyridine and substituted pyridine;

[0020] The application is specifically an application as a catalyst;

[0021] The polyethylene includes low entanglement ultra-high molecular weight polyethylene;

[0022] The viscosity average molecular weight of the polyethylene is greater than 1 million.

[0023] Preferably, the catalyst further comprises a main group alkyl reagent, or an organic boron salt and a main group alkyl reagent;

[0024] One or more of the main group alkyl reagent alkyl aluminum compound, alkyl aluminum oxide, alkyl zinc compound and alkyl magnesium compound;

[0025] The organic boron salt includes [B(C6F5)4] -1 Negative ion organic boron salt and / or B (C6F5) 3;

[0026] The preparation of polyethylene is specifically carried out by catalyzing ethylene homopolymerization to prepare polyethylene;

[0027] The preparation conditions include anhydrous and oxygen-free conditions.

[0028] The present invention provides a method for preparing a ligand of a binuclear rare earth compound, comprising the following steps:

[0029] 1) reacting 2,4,6-heptanetrione, a primary amine, a water scavenger, an acid, and an organic solvent to obtain a ligand represented by formula (II);

[0030]

[0031] The binuclear rare earth compound is the binuclear rare earth compound used in any one of the above technical solutions.

[0032] Preferably, the primary amine has a structure as shown in formula (III), R 1 -NH2 (III);

[0033] The dehydrating agent includes one or more of anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous calcium chloride, molecular sieves, titanium tetrachloride, trimethylchlorosilane and dimethyldichlorosilane;

[0034] The acid includes an organic acid and / or an inorganic acid;

[0035] The organic solvent includes one or more of toluene, benzene, xylene, chlorobenzene, dichloromethane, chloroform, tetrachloroethane, tetrahydrofuran and diethyl ether.

[0036] Preferably, the organic acid comprises one or more of formic acid, acetic acid and p-toluenesulfonic acid;

[0037] The inorganic acid includes one or more of hydrochloric acid, sulfuric acid and hydrobromic acid;

[0038] The reaction temperature is -20 to 50°C;

[0039] The reaction time is 10min to 48h;

[0040] The binuclear rare earth compound is prepared from the ligand through the following steps:

[0041] (1) The ligand (II) reacts with an alkyl lithium to obtain a ligand lithium salt;

[0042] (2) After reacting a trialkyl rare earth compound M(CH2R)3(L)n with PhNHMe2[B(C6H5)4], the lithium salt of the ligand (II) obtained in the above step is added and the reaction is continued to obtain a binuclear rare earth compound.

[0043] The present invention provides a method for preparing polyethylene, comprising the following steps:

[0044] 1) Under anhydrous and oxygen-free conditions, a catalyst system consisting of a binuclear rare earth compound, an organic boron salt, and a main-group alkyl reagent is used to catalyze the homopolymerization of ethylene to obtain polyethylene in an organic solvent or gas phase;

[0045] The binuclear rare earth compound has a structure as shown in formula (I):

[0046]

[0047] Among them, R 1 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted cycloalkyl group;

[0048] R is a silyl group, a substituted or unsubstituted aryl group;

[0049] M is a rare earth metal;

[0050] L is a Lewis base;

[0051] n is 0 or 1.

[0052] Preferably, the catalyst system is specifically prepared by reacting a binuclear rare earth compound, an organic boron salt and a solvent under anhydrous and oxygen-free conditions, and then adding a main group alkyl reagent to obtain a catalyst system;

[0053] The reaction time is 10 to 180 minutes;

[0054] The solvent includes one or more of a saturated alkane solvent, an aromatic hydrocarbon solvent, a substituted aromatic hydrocarbon solvent, a cycloalkane solvent and a substituted cycloalkane solvent;

[0055] The molar ratio of the binuclear rare earth compound to the organic boron salt is 1:(0.01-4);

[0056] The molar ratio of the binuclear rare earth compound to the main group alkyl reagent is 1:(1-1000).

[0057] Preferably, the organic boron salt comprises [NMe(C 18 H 37)2][B(C6F5)4], [Ph3C][B(C6F5)4], [PhNMe2H][B(C6F5)4] and B(C6F5)3;

[0058] The main group alkyl reagent includes methylaluminoxane, dried aluminoxane, modified aluminoxane, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-tert-butylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum; one or more of diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, dihexylaluminum hydride, diisohexylaluminum hydride, dioctylaluminum hydride, diisooctylaluminum hydride, ethylaluminum dihydride, n-propylaluminum dihydride, isobutylaluminum dihydride, diethylzinc, diethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium, dibutylmagnesium and ethylbutylmagnesium;

[0059] The organic solvent includes one or more of a saturated alkane solvent, an aromatic hydrocarbon solvent, a substituted aromatic hydrocarbon solvent, a cycloalkane solvent and a substituted cycloalkane solvent;

[0060] The homopolymerization temperature is 0 to 200° C.

[0061] The homopolymerization pressure is 0.1 to 30.0 MPa;

[0062] The homopolymerization time is preferably 1 min to 24 h.

[0063] The present invention provides the use of a binuclear rare earth compound in the preparation of polyethylene; the binuclear rare earth compound has a structure as shown in formula (I). The present invention also provides a method for preparing polyethylene. Compared with the prior art, the present invention addresses the existing low-entanglement UHMWPE, which primarily utilizes a single-active-site early transition metal catalyst system. Low-entanglement ultrahigh molecular weight polyethylene (UHMWPE) must be produced at low polymerization temperatures, low ethylene pressures, and extremely dilute catalyst concentrations. This presents problems such as harsh preparation process conditions, low production efficiency, and high product prices.

[0064] The present invention creatively applies a binuclear rare earth compound with a specific structure to the polyethylene production process, thereby obtaining low-entanglement ultra-high molecular weight polyethylene. The rare earth catalytic system provided by the present invention is a binuclear rare earth catalyst, which is a non-metallocene ligand chelated binuclear rare earth catalyst. The present invention uses a catalyst composition composed of a rare earth compound described by general formula (I) and / or an organic boron salt and a main-group alkyl reagent, which has very high catalytic activity for ethylene homopolymerization and can produce low-entanglement ultra-high molecular weight polyethylene over a wide temperature range and a wide ethylene pressure range. At the same time, even without the addition of an organic boron salt, the binary component composed of the rare earth compound and the main-group alkyl reagent can catalyze ethylene polymerization to produce ultra-high molecular weight polyethylene, but the activity is slightly reduced. Moreover, the present invention adopts a specific process route for the first time to prepare the ligand of general formula (II), which can be prepared in high yield from primary amines and 2,4,6-triheptanone at low temperature in a solvent containing a dehydrating agent, effectively solving the defect of the prior art that only primary amines with large steric hindrance can react with 2,4,6-triheptanone at high temperature to produce the target product, while primary amines with small steric hindrance cannot produce the target product at high temperature but instead form a disproportionated by-product.

[0065] The present invention provides a catalytic system and preparation method that can produce low-entanglement ultra-high molecular weight polyethylene in a wide temperature range, a wide ethylene pressure range and a wide catalyst concentration range. The preparation process is simple, the conditions are mild, and the controllability is strong, which is conducive to industrial application and commercial promotion.

[0066] Experimental results demonstrate that the use of a non-metallocene ligand chelated rare earth dinuclear compound, in the presence of a main-group alkyl reagent and / or an organoboron salt as a cocatalyst, exhibits exceptionally high catalytic activity for ethylene polymerization over a wide temperature range, ethylene pressure, and catalyst concentration, producing low-entanglement ultra-high molecular weight polyethylene (UHMWPE). This represents the only rare earth catalyst system demonstrated to date to be capable of catalyzing ethylene polymerization to produce low-entanglement UHMWPE over such a wide temperature and ethylene pressure range. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 A schematic diagram of the reaction route for preparing binuclear rare earth compounds using the ligand provided by the present invention;

[0068] Figure 2 The ligand 1 prepared in Example 1 of the present invention is 1 H-NMR spectrum;

[0069] Figure 3 The ligand 2 prepared in Example 2 of the present invention is 1 H-NMR spectrum;

[0070] Figure 4 The ligand 3 prepared in Example 3 of the present invention is 1H-NMR spectrum;

[0071] Figure 5 The ligand 6 prepared in Example 6 of the present invention is 1 H-NMR spectrum. DETAILED DESCRIPTION

[0072] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than for limiting the claims of the invention.

[0073] All raw materials of the present invention are not particularly limited in their sources and can be purchased from the market or prepared according to conventional methods well known to those skilled in the art.

[0074] There is no particular limitation on the purity of all raw materials in the present invention. The present invention preferably uses analytically pure materials or materials with conventional purity requirements in the field of polyolefin material preparation.

[0075] The present invention has no particular limitation on the expression of the substituents, and all expressions familiar to those skilled in the art are adopted. Based on common sense, those skilled in the art can correctly understand the meaning of the substituents according to the expressions.

[0076] All raw materials of the present invention, their brands or abbreviations are conventional brands or abbreviations in the field. Each brand and abbreviation is clear and unambiguous in the field of its relevant use. Those skilled in the art can purchase them from commercial sources or prepare them by conventional methods based on the brand, abbreviation and corresponding use.

[0077] The present invention provides the use of binuclear rare earth compounds in the preparation of polyethylene;

[0078] The binuclear rare earth compound has a structure as shown in formula (I):

[0079]

[0080] Wherein, R1 is a substituted or unsubstituted aryl group, a substituted or unsubstituted cycloalkyl group;

[0081] R is a silyl group, a substituted or unsubstituted aryl group;

[0082] M is a rare earth metal;

[0083] L is a Lewis base;

[0084] n is 0 or 1.

[0085] In the present invention, the polyethylene is preferably ultra-high molecular weight polyethylene.

[0086] In the present invention, the R 1Preferred include phenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 4-trifluoromethoxyphenyl, 4-phenoxyphenyl, 4-methylthiophenyl, 4-phenylphenyl, 4-benzylphenyl, 4-tritylphenyl, 4-N'N-dimethylphenyl, 4-fluorophenyl, 4-bromophenyl, 4-chlorophenyl, 4-iodophenyl, 2,6-difluorophenyl, 3,4-difluorophenyl, 3,4,5-trifluorophenyl, 3-methylphenyl, 3-ethylphenyl, 3-isopropylphenyl, 3-trifluoromethylphenyl, 3-methoxyphenyl, 3-phenylphenyl, 3-fluorophenyl, 3-chlorophenyl, 3-bromophenyl, 2-methylphenyl, 2- Ethylphenyl, 2-isopropylphenyl, 2-phenylaniline, 2-fluorophenyl, 2-chlorophenyl, 2-bromophenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylbenzene, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, 3,5-difluorophenyl, 3,5-trifluoromethylphenyl, 3,5-dimethylphenyl, 3,5-dimethoxyphenyl, 2,6-diethyl-4-methylphenyl, o-methoxyphenyl, o-methylthiophenyl, 2,6-diphenylphenyl, 4-methyl-2,6-dipentafluorophenylphenyl, 1-naphthyl, 2-naphthyl, cyclododecyl, cyclohexyl, p-tert-butylcyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl, cyclobutane The present invention further comprises one or more of phenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 4-trifluoromethoxyphenyl, 4-phenoxyphenyl, 4-methylthiophenyl, 4-phenylphenyl, 4-benzylphenyl, 4-tritylphenyl, 4-N'N-dimethylphenyl, 4-fluorophenyl, 4-bromophenyl, 4-chlorophenyl, 4-iodophenyl, 2,6-difluorophenyl, 3,4-difluorophenyl, 3,4,5-trifluorophenyl, 3-methylphenyl, 3-ethylphenyl, 3- -isopropylphenyl, 3-trifluoromethylphenyl, 3-methoxyphenyl, 3-phenylphenyl, 3-fluorophenyl, 3-chlorophenyl, 3-bromophenyl, 2-methylphenyl, 2-ethylphenyl, 2-isopropylphenyl, 2-phenylaniline, 2-fluorophenyl, 2-chlorophenyl, 2-bromophenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylbenzene, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, 3,5-difluorophenyl, 3,5-trifluoromethylphenyl, 3,5-dimethylphenyl, 3,5-dimethoxyphenyl, 2,6-diethyl-4-methylphenyl, o-methoxyphenyl, o-methylthiophenyl, 2,6-diphenylphenyl, 4-methyl-2,6-dipentafluorophenyl, phenyl, 1-naphthyl, 2-naphthyl, cyclododecyl, cyclohexyl, p-tert-butylcyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl, cyclobutane, cyclopropane, trans-4-methylcyclohexane, cis-2-methylcyclohexane, trans-2-methylcyclohexane or 3-methylcyclohexane.

[0087] In the present invention, the R preferably includes one or more of trimethylsilyl, phenyldimethylsilyl, phenyl and 4-methylphenyl, and more preferably trimethylsilyl, phenyldimethylsilyl, phenyl or 4-methylphenyl.

[0088] In the present invention, the binuclear rare earth compound is preferably a binuclear rare earth compound chelated with a non-cyclopentadienyl ligand.

[0089] In the present invention, the M preferably includes one or more of scandium, yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, more preferably scandium, yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium.

[0090] In the present invention, L preferably includes one or more of tetrahydrofuran, ethylene glycol dimethyl ether, tertiary amine, pyridine and substituted pyridine, and more preferably tetrahydrofuran, ethylene glycol dimethyl ether, tertiary amine, pyridine or substituted pyridine.

[0091] In the present invention, the application is preferably an application as a catalyst.

[0092] In the present invention, the polyethylene preferably comprises low entanglement ultra-high molecular weight polyethylene.

[0093] In the present invention, the viscosity average molecular weight of the polyethylene is preferably >1,000,000, more preferably >1,100,000, and even more preferably >1,200,000.

[0094] In the present invention, the catalyst preferably further comprises a main group alkyl reagent, or an organic boron salt and a main group alkyl reagent.

[0095] In the present invention, the main group alkyl reagent preferably includes one or more of alkyl aluminum compounds, alkyl aluminum oxides, alkyl zinc compounds and alkyl magnesium compounds, more preferably alkyl aluminum compounds, alkyl aluminum oxides, alkyl zinc compounds or alkyl magnesium compounds.

[0096] In the present invention, the organic boron salt preferably includes [B(C6F5)4] -1 Anion organic boron salt and / or B (C6F5) 3, more preferably containing [B (C6F5) 4] -1 Negative ion organic boron salt or B (C6F5) 3.

[0097] In the present invention, the preparation of polyethylene is preferably carried out by catalyzing ethylene homopolymerization.

[0098] In the present invention, the preparation conditions preferably include anhydrous and oxygen-free conditions.

[0099] The present invention provides a method for preparing a ligand of a binuclear rare earth compound, comprising the following steps:

[0100] 1) reacting 2,4,6-heptanetrione, a primary amine, a water scavenger, an acid, and an organic solvent to obtain a ligand represented by formula (II);

[0101]

[0102] The binuclear rare earth compound is the binuclear rare earth compound used in any one of the above technical solutions.

[0103] The definitions, selection ranges and preferred methods of the substituents in the above preparation method are consistent with those in formula (I), and are not described in detail here.

[0104] In the present invention, the primary amine preferably has a structure as shown in formula (III), R 1 -NH2 (III). The definitions, selection ranges and preferred embodiments of the substituents in the structure represented by the above formula (III) are consistent with those in formula (I), and are not described in detail here.

[0105] In the present invention, the dehydrating agent preferably includes one or more of anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous calcium chloride, molecular sieves, titanium tetrachloride, trimethylchlorosilane and dimethyldichlorosilane, more preferably anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous calcium chloride, molecular sieves, titanium tetrachloride, trimethylchlorosilane or dimethyldichlorosilane.

[0106] In the present invention, the acid preferably includes an organic acid and / or an inorganic acid, more preferably an organic acid or an inorganic acid.

[0107] In the present invention, the organic solvent preferably includes one or more of toluene, benzene, xylene, chlorobenzene, dichloromethane, chloroform, tetrachloroethane, tetrahydrofuran and diethyl ether, more preferably toluene, benzene, xylene, chlorobenzene, dichloromethane, chloroform, tetrachloroethane, tetrahydrofuran or diethyl ether.

[0108] In the present invention, the organic acid preferably includes one or more of formic acid, acetic acid and p-toluenesulfonic acid, more preferably formic acid, acetic acid or p-toluenesulfonic acid.

[0109] In the present invention, the inorganic acid preferably includes one or more of hydrochloric acid, sulfuric acid and hydrobromic acid, more preferably hydrochloric acid, sulfuric acid or hydrobromic acid.

[0110] In the present invention, the reaction temperature is preferably -20 to 50°C, more preferably -5 to 35°C, and even more preferably 10 to 20°C.

[0111] In the present invention, the reaction time is preferably 10 min to 48 h, more preferably 30 min to 24 h, more preferably 1 h to 12 h, and more preferably 6 h to 12 h.

[0112] In the present invention, the binuclear rare earth compound is preferably prepared from the ligand by the following steps:

[0113] (1) The ligand (II) reacts with an alkyl lithium to obtain a ligand lithium salt;

[0114] (2) After reacting a trialkyl rare earth compound M(CH2R)3(L)n with PhNHMe2[B(C6H5)4], the lithium salt of the ligand (II) obtained in the above step is added and the reaction is continued to obtain a binuclear rare earth compound.

[0115] The definitions, selection ranges and preferred methods of the substituents in the above preparation method are consistent with those in formula (I), and are not described in detail here.

[0116] Specifically, the above binuclear rare earth compound can be prepared from the ligand through the following steps:

[0117] The ligand represented by formula II is reacted with 2 times the molar amount of alkyl lithium in tetrahydrofuran at room temperature for 1 hour to obtain the lithium salt of the ligand represented by formula II;

[0118] After reacting a trialkyl rare earth compound M(CH2R)3(L)n with PhNHMe2[B(C6H5)4] in tetrahydrofuran at room temperature for 2 hours, a lithium salt of a ligand of Formula II was added, followed by reaction at room temperature for 1 hour. After completion of the reaction, all solvents were removed in vacuo, and an appropriate amount of toluene was added to the solid product to extract the product. The filtrate was filtered, collected, concentrated, and recrystallized at -30°C to obtain a binuclear rare earth compound of Formula I.

[0119] See also Figure 1 , Figure 1 The present invention provides a schematic diagram of the reaction route for preparing binuclear rare earth compounds using the ligand provided by the present invention.

[0120] The present invention provides a method for preparing polyethylene, comprising the following steps:

[0121] 1) Under anhydrous and oxygen-free conditions, a catalyst system consisting of a binuclear rare earth compound, an organic boron salt, and a main-group alkyl reagent is used to catalyze the homopolymerization of ethylene to obtain polyethylene in an organic solvent or gas phase;

[0122] The binuclear rare earth compound has a structure as shown in formula (I):

[0123]

[0124] Among them, R 1 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted cycloalkyl group;

[0125] R is a silyl group, a substituted or unsubstituted aryl group;

[0126] M is a rare earth metal;

[0127] L is a Lewis base;

[0128] n is 0 or 1.

[0129] In the present invention, the catalyst system is preferably obtained by reacting a binuclear rare earth compound, an organic boron salt and a solvent under anhydrous and oxygen-free conditions, and then adding a main group alkyl reagent.

[0130] In the present invention, the reaction time is preferably 10 to 180 minutes, more preferably 40 to 150 minutes, and even more preferably 70 to 120 minutes.

[0131] In the present invention, the solvent preferably includes one or more of saturated alkane solvents, aromatic hydrocarbon solvents, substituted aromatic hydrocarbon solvents, cycloalkane solvents and substituted cycloalkane solvents, more preferably saturated alkane solvents, aromatic hydrocarbon solvents, substituted aromatic hydrocarbon solvents, cycloalkane solvents or substituted cycloalkane solvents.

[0132] In the present invention, the molar ratio of the binuclear rare earth compound to the organic boron salt is preferably 1:(0.01-4), more preferably 1:(0.1-3), and even more preferably 1:(1-2).

[0133] In the present invention, the molar ratio of the binuclear rare earth compound to the main group alkyl reagent is preferably 1:(1-1000), more preferably 1:(5-800), more preferably 1:(10-400), more preferably 1:(20-200), and more preferably 1:(20-100).

[0134] In the present invention, the organic boron salt preferably includes [NMe(C 18 H 37 )2][B(C6F5)4], [Ph3C][B(C6F5)4], [PhNMe2H][B(C6F5)4] and B(C6F5)3, more preferably [NMe(C 18 H 37 )2][B(C6F5)4], [Ph3C][B(C6F5)4], [PhNMe2H][B(C6F5)4] or B(C6F5)3.

[0135] In the present invention, the main group alkyl reagent preferably includes methylaluminoxane, dried aluminoxane, modified aluminoxane, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-tert-butylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum; diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, dihexylaluminum hydride, diisohexylaluminum hydride, dioctylaluminum hydride, diisooctylaluminum hydride, ethylaluminum dihydride, n-propylaluminum dihydride, isobutylaluminum dihydride, diethylzinc, diethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium, dibutylmagnesium and ethyl One or more of the butyl magnesium, more preferably methylaluminoxane, dried aluminoxane, modified aluminoxane, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-tert-butylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum; diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, dihexylaluminum hydride, diisohexylaluminum hydride, dioctylaluminum hydride, diisooctylaluminum hydride, ethylaluminum dihydride, n-propylaluminum dihydride, isobutylaluminum dihydride, diethylzinc, diethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium, dibutylmagnesium or ethylbutylmagnesium.

[0136] In the present invention, the organic solvent preferably includes one or more of saturated alkane solvents, aromatic hydrocarbon solvents, substituted aromatic hydrocarbon solvents, cycloalkane solvents and substituted cycloalkane solvents, more preferably saturated alkane solvents, aromatic hydrocarbon solvents, substituted aromatic hydrocarbon solvents, cycloalkane solvents or substituted cycloalkane solvents.

[0137] In the present invention, the homopolymerization temperature is preferably 0 to 200°C, more preferably 20 to 160°C, and even more preferably 40 to 100°C.

[0138] In the present invention, the homopolymerization pressure is preferably 0.1 to 30.0 MPa, more preferably 0.2 to 20.0 MPa, more preferably 0.2 to 10.0 MPa, and even more preferably 0.2 to 1.5 MPa.

[0139] In the present invention, the homopolymerization time is preferably 1 min to 24 h, more preferably 10 min to 12 h, more preferably 0.5 h to 6 h, and more preferably 1 h to 4 h.

[0140] The present invention is a complete and detailed overall technical solution that ensures the structure and properties of the binuclear rare earth compound, improves its application efficiency in the preparation of polyethylene, and further improves the preparation excellence and properties of low-entanglement ultra-high molecular weight polyethylene. The preparation method of the low-entanglement ultra-high molecular weight polyethylene may specifically include the following contents:

[0141] A method for preparing low-entanglement ultra-high molecular weight polyethylene comprises the following steps:

[0142] Under anhydrous and oxygen-free conditions, a catalyst composition composed of a rare earth compound represented by general formula (I), an organic boron salt, and a main-group alkyl reagent is used to catalyze the homopolymerization of ethylene in an organic solvent to produce low-entanglement ultrahigh molecular weight polyethylene;

[0143] The structure of the rare earth compound is shown in general formula (I):

[0144]

[0145] In the general formula (I):

[0146] R 1is aryl, substituted aryl, cycloalkyl, or substituted cycloalkyl; preferably phenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 4-trifluoromethoxyphenyl, 4-phenoxyphenyl, 4-methylthiophenyl, 4-phenylphenyl, 4-benzylphenyl, 4-tritylphenyl, 4-N'N-dimethylphenyl, 4-fluorophenyl, 4-bromophenyl, 4-chlorophenyl, 4-iodophenyl, 2,6-difluorophenyl, 3,4-difluorophenyl, 3,4,5-trifluorophenyl, 3-methylphenyl, 3-ethylphenyl, or 3-isopropylphenyl. , 3-trifluoromethylphenyl, 3-methoxyphenyl, 3-phenylphenyl, 3-fluorophenyl, 3-chlorophenyl, 3-bromophenyl, 2-methylphenyl, 2-ethylphenyl, 2-isopropylphenyl, 2-phenylaniline, 2-fluorophenyl, 2-chlorophenyl, 2-bromophenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylbenzene, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, 3,5-difluorophenyl, 3,5-trifluoromethylphenyl, 3,5-dimethylphenyl, 3,5-dimethoxyphenyl, 2,6-diethyl-4-methylphenyl, o-methoxy Phenyl, o-methylthiophenyl, 2,6-diphenylphenyl, 4-methyl-2,6-dipentafluorophenylphenyl, 1-naphthyl, 2-naphthyl, cyclododecyl, cyclohexyl, p-tert-butylcyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl, cyclobutane, cyclopropyl, trans-4-methylcyclohexyl, cis-2-methylcyclohexyl, trans-2-methylcyclohexane, 3-methylcyclohexane; more preferably phenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 4-trifluoromethoxyphenyl, 4-methylthiophenyl, 4 -phenylphenyl, 3-methylphenyl, 3-ethylphenyl, 3-isopropylphenyl, 2-methylphenyl, 2-ethylphenyl, 2-isopropylphenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylbenzene, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, 3,5-dimethylphenyl, 3,5-dimethoxyphenyl, 2,6-diethyl-4-methylphenyl, o-methoxyphenyl, o-methylthiophenyl, 2,6-diphenylphenyl, 1-naphthyl, 2-naphthyl, cyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl, cyclobutane, cyclopropyl;More preferably, phenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 3-methylphenyl, 3-ethylphenyl, 3-isopropylphenyl, 2-methylphenyl, 2-ethylphenyl, 2-isopropylphenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylphenyl, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, 3,5-dimethylphenyl, 2,6-diethyl-4-methylphenyl, phenyl, 2,6-diphenylphenyl, 1-naphthyl, 2-naphthyl, cyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl; most preferably phenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 2-isopropylphenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylphenyl, 2,4,6-triisopropylphenyl, 2,6-diphenylphenyl, cyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl. ;

[0147] R is a silyl group, an aryl group, or a substituted aryl group; preferably, trimethylsilyl, phenyldimethylsilyl, phenyl, or 4-methylphenyl.

[0148] M is a rare earth metal element of scandium, yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium or lutetium;

[0149] L is a Lewis base tetrahydrofuran, ethylene glycol dimethyl ether, a tertiary amine, pyridine or a substituted pyridine;

[0150] n is 0 or 1.

[0151] Specifically, the organic boron salt preferably contains [B(C6F5)4] -1 Anion organic boron salt and B (C6F5) 3; more preferably [NMe (C 18 H 37 )2][B(C6F5)4], [Ph3C][B(C6F5)4], [PhNMe2H][B(C6F5)4] and B(C6F5)3.

[0152] Specifically, the main group alkyl reagent is selected from one or more of an organoaluminum compound, an organoaluminum oxide, an organozinc compound, and an organomagnesium compound. The main group alkyl reagent is selected from one or more of aluminoxane, alkylaluminum, alkylzinc, and alkylmagnesium reagents. In the present invention, the alkylaluminum is preferably selected from trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-tert-butylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, and trioctylaluminum; one or more of diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, dihexylaluminum hydride, diisohexylaluminum hydride, dioctylaluminum hydride, diisooctylaluminum hydride, ethylaluminum dihydride, n-propylaluminum dihydride, and isobutylaluminum dihydride; the aluminoxane is selected from one or more of methylaluminoxane (MAO), dried aluminoxane (DMAO), and modified aluminoxane (MMAO). The alkyl zinc is preferably diethyl zinc; the alkyl magnesium is preferably selected from one or more of diethyl magnesium, di-n-propyl magnesium, diisopropyl magnesium, dibutyl magnesium and ethylbutyl magnesium.

[0153] Specifically, in the catalyst composition, the molar ratio of the rare earth compound, the organic boron salt compound, and the main group alkyl reagent is 1:(0-4):(1-1000); the molar ratio of the rare earth compound to the main group alkyl reagent is preferably 1:(1-500), more preferably 1:(2-200). The molar ratio of the rare earth compound to the organic boron salt compound is preferably 1:(0.01-4), more preferably 1:(0.1-3), more preferably 1:(1-2), and most preferably 1:2.

[0154] Specifically, the polymerization reaction temperature is preferably 0-200°C; more preferably 20-160°C; more preferably 20-140°C; more preferably 40-120°C; and most preferably 40-100°C.

[0155] Specifically, the polymerization reaction pressure is preferably 0.1 to 30.0 MPa; more preferably 0.2 to 20.0 MPa; more preferably 0.2 to 10.0 MPa; more preferably 0.2 to 5.0 MPa; and most preferably 0.2 to 1.5 MPa.

[0156] Specifically, the polymerization reaction time is preferably 1 min to 24 h, more preferably 10 min to 12 h, more preferably 0.5 h to 6 h, and more preferably 1 h to 4 h.

[0157] Specifically, the polymerization reaction is carried out in an organic solvent or in a gas phase; the organic solvent is preferably one or more of saturated alkanes, aromatic hydrocarbons, substituted aromatic hydrocarbons, cycloalkanes, and substituted cycloalkanes, more preferably one or more of No. 6 solvent oil, n-hexane, decahydronaphthalene, cyclohexane, petroleum ether, chlorobenzene, benzene, toluene and xylene.

[0158] A method for preparing a non-cyclopentadienyl ligand of general formula (II) comprises adding 2,4,6-heptanetrione and a primary amine to an organic solvent containing a dehydrating agent and an organic acid or an inorganic acid and reacting them at low temperature to produce the ligand of general formula (II). The preparation reaction formula is shown below:

[0159]

[0160] Specifically, the dehydrating agent is preferably anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous calcium chloride, molecular sieve, titanium tetrachloride, trimethylchlorosilane, dimethyldichlorosilane; more preferably anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous calcium chloride, molecular sieve.

[0161] Specifically, the organic acid is preferably formic acid, acetic acid, or p-toluenesulfonic acid, and the inorganic acid is preferably hydrochloric acid, sulfuric acid, or hydrobromic acid.

[0162] Specifically, the low temperature condition is preferably -20 to 50°C; more preferably -10 to 40°C; more preferably 0 to 30°C; and most preferably 10 to 30°C.

[0163] Specifically, the organic solvent is preferably toluene, benzene, xylene, chlorobenzene, dichloromethane, chloroform, tetrachloroethane, tetrahydrofuran, and diethyl ether; more preferably toluene, xylene, dichloromethane, chloroform, tetrahydrofuran, and diethyl ether; most preferably toluene, dichloromethane, chloroform, and tetrahydrofuran.

[0164] Specifically, the reaction time is preferably 10 min to 48 h; more preferably 30 min to 24 h; more preferably 1 h to 12 h; more preferably 6 h to 12 h.

[0165] The above content of the present invention provides the application of binuclear rare earth compounds in the preparation of polyethylene, a method for preparing a ligand of a binuclear rare earth compound, and a method for preparing low-entanglement ultra-high molecular weight polyethylene. The present invention uses a binuclear rare earth compound with a specific structure and applies it to the polyethylene preparation process, thereby obtaining low-entanglement ultra-high molecular weight polyethylene. The rare earth catalytic system provided by the present invention is a binuclear rare earth catalyst, which is a non-metallic ligand chelated binuclear rare earth catalyst. The present invention uses a catalyst composition composed of a rare earth compound described in general formula (I) and / or an organic boron salt and a main group alkyl reagent, which has very high catalytic activity for ethylene homopolymerization and can produce low-entanglement ultra-high molecular weight polyethylene in a wide temperature range and a wide ethylene pressure range. At the same time, even without the addition of an organic boron salt, the binary component composed of the rare earth compound and the main group alkyl reagent can catalyze ethylene polymerization to produce ultra-high molecular weight polyethylene, but the activity is slightly reduced. Moreover, the present invention adopts a specific process route for the first time to prepare the ligand of general formula (II), which can be prepared in high yield from primary amines and 2,4,6-triheptanone at low temperature in a solvent containing a dehydrating agent, effectively solving the defect of the prior art that only primary amines with large steric hindrance can react with 2,4,6-triheptanone at high temperature to produce the target product, while primary amines with small steric hindrance cannot produce the target product at high temperature but instead form a disproportionated by-product.

[0166] The present invention provides a catalytic system and preparation method that can produce low-entanglement ultra-high molecular weight polyethylene in a wide temperature range, a wide ethylene pressure range and a wide catalyst concentration range. The preparation process is simple, the conditions are mild, and the controllability is strong, which is conducive to industrial application and commercial promotion.

[0167] Experimental results demonstrate that the use of a non-metallocene ligand chelated rare earth dinuclear compound, in the presence of a main-group alkyl reagent and / or an organoboron salt as a cocatalyst, exhibits exceptionally high catalytic activity for ethylene polymerization over a wide temperature range, ethylene pressure, and catalyst concentration, producing low-entanglement ultra-high molecular weight polyethylene (UHMWPE). This represents the only rare earth catalyst system demonstrated to date to be capable of catalyzing ethylene polymerization to produce low-entanglement UHMWPE over such a wide temperature and ethylene pressure range.

[0168] In order to further illustrate the present invention, the application of the binuclear rare earth compound provided by the present invention in the preparation of polyethylene, a method for preparing a ligand of a binuclear rare earth compound, and a method for preparing polyethylene are described in detail below in combination with the examples. However, it should be understood that these examples are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating processes are provided only to further illustrate the characteristics and advantages of the present invention, rather than to limit the claims of the present invention. The scope of protection of the present invention is not limited to the following examples.

[0169] The present invention has no particular limitation on the sources of the raw materials in the following examples, and the raw materials can be prepared by methods well known to those skilled in the art or purchased from the market.

[0170] Ligand Preparation Example 1

[0171] 2,4,6-Heptanetrione (14.2 g), aniline (25.6 g), p-toluenesulfonic acid (1.9 g), anhydrous magnesium sulfate (8 g) and toluene (30 mL) were added to a round-bottom flask placed in a water bath at 10°C. After reacting at this temperature for 12 hours, the filtrate was collected by filtration, concentrated, and then recrystallized at -18°C, filtered, washed with petroleum ether, and dried to obtain ligand 1 with a yield of 81%.

[0172]

[0173] See also Figure 2 , Figure 2 The ligand 1 prepared in Example 1 of the present invention is 1 H-NMR spectrum.

[0174] Ligand Preparation Example 2

[0175] 2,4,6-Heptanetrione (14.2 g), 2,4,6-trimethylaniline (30.0 g), p-toluenesulfonic acid (1.9 g), anhydrous magnesium sulfate (8 g) and toluene (30 mL) were added to a round-bottom flask placed in a water bath at 10°C. After reacting at this temperature for 12 hours, the filtrate was collected by filtration, concentrated, and then recrystallized at -18°C, filtered, washed with petroleum ether, and dried to obtain ligand 2 with a yield of 74%.

[0176]

[0177] See also Figure 3 , Figure 3 The ligand 2 prepared in Example 2 of the present invention is 1 H-NMR spectrum.

[0178] Ligand Preparation Example 3

[0179] 2,4,6-Heptanetrione (14.2 g), o-anisidine (26.0 g), p-toluenesulfonic acid (1.9 g), anhydrous magnesium sulfate (8 g) and toluene (30 mL) were added to a round-bottom flask placed in a water bath at 10°C. After reacting at this temperature for 12 hours, the filtrate was collected by filtration, drained, washed with petroleum ether, and dried to obtain ligand 3 with a yield of 68%.

[0180]

[0181] See also Figure 4 , Figure 4 The ligand 3 prepared in Example 3 of the present invention is1 H-NMR spectrum.

[0182] Ligand Preparation Example 4

[0183] 2,4,6-Heptanetrione (14.2 g), 2,6-diisopropylaniline (35.4 g), p-toluenesulfonic acid (1.9 g), anhydrous magnesium sulfate (8 g) and toluene (30 mL) were added to a round-bottom flask placed in a water bath at 10°C. After reacting at this temperature for 12 hours, the filtrate was collected by filtration, concentrated, and then recrystallized at -18°C. After filtration and drying, ligand 4 was obtained with a yield of 85%.

[0184]

[0185] Ligand Preparation Example 5

[0186] 2,4,6-Heptanetrione (14.2 g), 2,6-diethylaniline (30.0 g), p-toluenesulfonic acid (1.9 g), anhydrous magnesium sulfate (8 g) and toluene (30 mL) were added to a round-bottom flask placed in a water bath at 10°C. After reacting at this temperature for 12 hours, the filtrate was collected by filtration, concentrated, and then recrystallized at -18°C. After filtration and drying, ligand 5 was obtained with a yield of 84%.

[0187]

[0188] Ligand Preparation Example 6

[0189] 2,4,6-heptanetrione (14.2 g), o-isopropylaniline (30.0 g), p-toluenesulfonic acid (1.9 g), anhydrous magnesium sulfate (8 g) and toluene (30 mL) were added to a round-bottom flask placed in a water bath at 10°C. After reacting at this temperature for 12 hours, the filtrate was collected by filtration, concentrated, and then recrystallized at -18°C. After filtration and drying, ligand 6 was obtained with a yield of 83%.

[0190] See also Figure 5 , Figure 5 The ligand 6 prepared in Example 6 of the present invention is 1 H-NMR spectrum.

[0191]

[0192] The above complexes were synthesized according to the literature method Chem. Eur. J. 2014, 20, 15493-15498.

[0193] Polymerization Example 1

[0194] Under anhydrous and oxygen-free conditions, 10 μmol of rare earth compound 1 and 20 μmol of [Ph3C][B(C6F5)4](A) were reacted in 3 mL of toluene at room temperature for 20 min, and then 100 μmol of Al i Bu3 was used to prepare a catalyst composition solution. The chlorobenzene solution of the catalyst composition was then injected into a reaction flask containing 150 mL of toluene solvent. After reacting for 1 minute at 2 bar ethylene pressure and 20°C, ethanol acidified with hydrochloric acid was added to terminate the polymerization reaction, producing 2.63 g of polyethylene. Its molecular weight M v =281×10 4 g / mol, melting temperature T m =150℃.

[0195] Polymerization Examples 2 to 17

[0196] Except for the conditions described in the table, other polymerization conditions of Examples 2 to 17 are the same as those of Example 1.

[0197] See Table 1, which shows the preparation conditions and product characteristics of polymerization examples 1 to 17 of the present invention.

[0198] Table 1

[0199]

[0200] Among them, [Ph3C][B(C6F5)4](A); B(C6F5)3(B); [NMe(C 18 H 37 )2][B(C6F5)4](C).

[0201] The above describes in detail the use of the binuclear rare earth compound in the preparation of polyethylene, a method for preparing a ligand for the binuclear rare earth compound, and a method for preparing low-entanglement ultrahigh molecular weight polyethylene provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above examples is intended only to facilitate understanding of the methods and core concepts of the present invention, including the best mode, and to enable any person skilled in the art to practice the present invention, including the manufacture and use of any device or system, and the implementation of any combined method. It should be noted that, without departing from the principles of the present invention, a person skilled in the art may make various improvements and modifications to the present invention, and such improvements and modifications fall within the scope of the claims. The scope of patent protection for the present invention is defined by the claims and may include other embodiments that may be conceived by those skilled in the art. If these other embodiments have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims, then these other embodiments are also intended to be included within the scope of the claims.

Claims

1. Application of binuclear rare earth compounds in the preparation of polyethylene; The binuclear rare earth compound has a structure as shown in formula (I): （I）； in, R 1 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted cycloalkyl group; R is a silyl group, a substituted or unsubstituted aryl group; M is a rare earth metal; L is a Lewis base; n is 0 or 1; The polyethylene is ultra-high molecular weight polyethylene; The application is specifically an application as a catalyst.

2. The use according to claim 1, characterized in that The R 1 Including phenyl, 4-methylphenyl, 4-ethylphenyl, 4-isopropylphenyl, 4-tert-butylphenyl, 4-trifluoromethylphenyl, 4-methoxyphenyl, 4-ethoxyphenyl, 4-trifluoromethoxyphenyl, 4-phenoxyphenyl, 4-methylthiophenyl, 4-phenylphenyl, 4-benzylphenyl, 4-tritylphenyl, 4-fluorophenyl, 4-bromophenyl, 4-chlorophenyl, 4-iodophenyl, 2,6-difluorophenyl, 3,4-difluorophenyl, 3,4,5-trifluorophenyl, 3-methylphenyl, 3-ethylphenyl, 3-isopropylphenyl, 3-trifluoromethylphenyl, 3-methoxyphenyl, 3-phenylphenyl, 3-fluorophenyl, 3-chlorophenyl, 3-bromophenyl, 2-methylphenyl, 2-ethylphenyl, 2-isopropylphenyl, 2-phenylaniline, 2-fluorophenyl, 2-chlorophenyl, 2- One of bromophenyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-diethylphenyl, 2,6-diisopropylbenzene, 2,4,6-triethylphenyl, 2,4,6-triisopropylphenyl, 3,5-difluorophenyl, 3,5-trifluoromethylphenyl, 3,5-dimethylphenyl, 3,5-dimethoxyphenyl, 2,6-diethyl-4-methylphenyl, o-methoxyphenyl, o-methylthiophenyl, 2,6-diphenylphenyl, 4-methyl-2,6-dipentafluorophenylphenyl, 1-naphthyl, 2-naphthyl, cyclododecyl, cyclohexyl, p-tert-butylcyclohexyl, cyclooctyl, cycloheptyl, cyclopentyl, cyclobutane, cyclopropyl, trans-4-methylcyclohexane, cis-2-methylcyclohexane, trans-2-methylcyclohexane and 3-methylcyclohexane; The R comprises one of trimethylsilyl, phenyldimethylsilyl, phenyl and 4-methylphenyl; The binuclear rare earth compound is a binuclear rare earth compound chelated with a non-cyclopentadienyl ligand.

3. The use according to claim 1, characterized in that The M comprises one of scandium, yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium; The L comprises one of tetrahydrofuran, ethylene glycol dimethyl ether, tertiary amine, pyridine and substituted pyridine; The polyethylene includes low entanglement ultra-high molecular weight polyethylene; The viscosity average molecular weight of the polyethylene is greater than 1 million.

4. The use according to claim 3, characterized in that The catalyst further comprises a main group alkyl reagent, or an organic boron salt and a main group alkyl reagent; The main group alkyl reagent is one or more of an alkyl aluminum compound, an alkyl zinc compound and an alkyl magnesium compound; The organic boron salt includes [B(C6F5)4] -1 Negative ion organic boron salt and / or B (C6F5) 3; The preparation of polyethylene is specifically carried out by catalyzing ethylene homopolymerization to prepare polyethylene; The preparation conditions include anhydrous and oxygen-free conditions.

5. The use according to claim 1, characterized in that The method for preparing the ligand of the binuclear rare earth compound comprises the following steps: 1) reacting 2,4,6-heptanetrione, a primary amine, a water scavenger, an acid, and an organic solvent to obtain a ligand represented by formula (II); (II)。 6. The use according to claim 5, characterized in that The primary amine has a structure as shown in formula (III), (III); The dehydrating agent includes one or more of anhydrous magnesium sulfate, anhydrous sodium sulfate, anhydrous calcium chloride, molecular sieves, titanium tetrachloride, trimethylchlorosilane and dimethyldichlorosilane; The acid includes an organic acid and / or an inorganic acid; The organic solvent includes one or more of toluene, benzene, xylene, chlorobenzene, dichloromethane, chloroform, tetrachloroethane, tetrahydrofuran and diethyl ether.

7. The use according to claim 6, characterized in that The organic acid includes one or more of formic acid, acetic acid and p-toluenesulfonic acid; The inorganic acid includes one or more of hydrochloric acid, sulfuric acid and hydrobromic acid.

8. The use according to claim 6, characterized in that The reaction temperature is -20~50°C; The reaction time is 10 min to 48 h.

9. A method for preparing polyethylene, characterized in that: The following steps are involved: 1) Under anhydrous and oxygen-free conditions, a catalyst system consisting of a binuclear rare earth compound, an organic boron salt, and a main-group alkyl reagent is used to catalyze the homopolymerization of ethylene to produce polyethylene in an organic solvent or gas phase; The binuclear rare earth compound has a structure as shown in formula (I): （I）； Among them, R 1 is a substituted or unsubstituted aryl group, or a substituted or unsubstituted cycloalkyl group; R is a silyl group, a substituted or unsubstituted aryl group; M is a rare earth metal; L is a Lewis base; n is 0 or 1; The polyethylene is ultra-high molecular weight polyethylene; The main group alkyl reagent is one or more of an alkyl aluminum compound, an alkyl zinc compound and an alkyl magnesium compound.

10. The preparation method according to claim 9, characterized in that The catalyst system is specifically prepared by reacting a binuclear rare earth compound, an organic boron salt and a solvent under anhydrous and oxygen-free conditions, and then adding a main group alkyl reagent to obtain a catalyst system; The reaction time is 10 to 180 minutes; The solvent includes one or more of a saturated alkane solvent, an aromatic hydrocarbon solvent, a substituted aromatic hydrocarbon solvent, a cycloalkane solvent and a substituted cycloalkane solvent; The molar ratio of the binuclear rare earth compound to the organic boron salt is 1:(0.01-4); The molar ratio of the binuclear rare earth compound to the main group alkyl reagent is 1: (1-1000).

11. The preparation method according to claim 9, characterized in that The organic boron salts include [NMe(C 18 H 37 )2][B(C6F5)4], [Ph3C][B(C6F5)4], [PhNMe2H][B(C6F5)4] and B(C6F5)3; The main group alkyl reagent includes methylaluminoxane, dried aluminoxane, modified aluminoxane, trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisopropylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-tert-butylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum; one or more of diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisobutylaluminum hydride, dihexylaluminum hydride, dioctylaluminum hydride, ethylaluminum dihydride, n-propylaluminum dihydride, isobutylaluminum dihydride, diethylzinc, diethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium, dibutylmagnesium and ethylbutylmagnesium; The organic solvent includes one or more of a saturated alkane solvent, an aromatic hydrocarbon solvent, a substituted aromatic hydrocarbon solvent, a cycloalkane solvent and a substituted cycloalkane solvent; The homopolymerization temperature is 0-200°C; The homopolymerization pressure is 0.1-30.0 MPa; The homopolymerization time is 1 min to 24 h.

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