Preparation method of ethylene-styrene random copolymer

Abstract

The invention provides a preparation method of an ethylene-styrene random copolymer, ethylene and styrene are used as raw materials for a copolymerization reaction, a catalyst comprises a rare earth complex, and the rare earth complex has a structure as shown in a formula I: # imgabs0 #, r1 is cyclopentadienyl with a structure shown in a formula II and a derivative thereof, indenyl with a structure shown in a formula III and a derivative thereof, or fluorenyl with a structure shown in a formula IV and a derivative thereof; # imgabs1 # R2, R3 are independently selected from the group consisting of a hydrocarbyl group having 1 to 20 carbons or hydrogen; ln is rare earth metal, S is sulfur, E is C, Si or Ge, and Y is tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether or methylbenzene; r4 is alkyl of C1 to C20, silyl of C1 to C20, alkylamino of C1 to C20, arylamino, borohydride or allyl; m = 1 or 2; n = 0, 1 or 2. The insertion rate of styrene in the ethylene-styrene random copolymer prepared by the method is high.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to a method for preparing an ethylene-styrene random copolymer. Background Art

[0002] Polyolefin polymer materials are widely used in fields such as agriculture, medical and health, military, and people's daily lives due to their high cost performance and excellent mechanical properties. However, the polyolefin molecular chain mainly consists of carbon and hydrogen elements and lacks polar groups, which limits the application of polyolefins in many fields. Introducing polar groups into polyolefins can greatly improve the surface properties, adhesion, dyeing properties, dielectric properties of polyolefins, as well as the compatibility and blending properties of polyolefins with other materials, thereby increasing the added value of polyolefins and expanding the application fields of polyolefins. This has become one of the important directions for the development of polyolefins and research in the industry today.

[0003] Ethylene and styrene monomers are two very important monomers that make up polyolefin polymer materials. However, due to the large difference in the nature of the active species of the catalysts that initiate these two types of monomers, polymerization methods such as free radical and traditional Ziegler-Natta catalytic systems cannot effectively catalyze the copolymerization of these two types of monomers to synthesize copolymers. It wasn't until the emergence of transition metal single-active-site homogeneous catalysts that researchers used single-cyclopentadienyl titanium and constrained geometry configuration (CGC) titanium catalytic systems to achieve the copolymerization of ethylene and styrene. For example, as published by Carpentier et al. (Chem. Eur. J. 2007, 13, 5548, CN200580013508.4), using a neodymocene allyl compound to catalyze the copolymerization of ethylene and styrene to prepare an ethylene-styrene copolymer with a very high content of syndiotactic polystyrene segments.

[0004] CN102181005A discloses a method for preparing a styrene-ethylene copolymer using a rare earth catalytic system. Styrene and ethylene are used as monomers, and a polymerization system is composed of a catalyst solution and a solvent. The characteristics are: polymerization is carried out under an inert atmosphere, the polymerization temperature is 15°C to 120°C, the catalyst solution contains a rare earth amido complex, an alkyl aluminum, and an organic borate, and the solvent is an organic solvent without active hydrogen. This invention uses a rare earth catalytic system. The synthesis of the rare earth amido complex is simple and its thermal stability is improved, which is not only beneficial for synthesis and preservation, but also beneficial for effective polymerization without decomposition within a relatively wide polymerization temperature range. Moreover, the activity of the catalyst can be adjusted by adjusting the structure of the rare earth complex, that is, by changing the structure of the ligands attached around the central metal to control the composition and sequence distribution of the copolymer.

[0005] However, in the prior art, during the polymerization of ethylene and styrene, the insertion rate of styrene is relatively low and needs to be further improved. Summary of the Invention

[0006] The main object of the present invention is to provide a method for preparing an ethylene-styrene random copolymer to overcome the problem of low styrene insertion rate in the ethylene-styrene random copolymer in the prior art.

[0007] To achieve the above object, the present invention provides a method for preparing an ethylene-styrene random copolymer, which uses ethylene and styrene as raw materials for copolymerization reaction, and the catalyst includes a rare earth complex, and the rare earth complex has the following structure of formula I:

[0008]

[0009] Among them, R 1 is a cyclopentadienyl and its derivatives having the structure of formula II, an indenyl and its derivatives having the structure of formula III, or a fluorenyl and its derivatives having the structure of formula IV;

[0010]

[0011] R 2 , R 3 are independently selected from a hydrocarbon group or hydrogen, and the hydrocarbon group has 1-20 carbons;

[0012] Ln is a rare earth metal, S is sulfur, E is C, Si or Ge, Y is tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether or toluene; R 4 is an alkyl group of C1-C20, a silyl group of C1-C20, an alkylamino group of C1-C20, an arylamino group of C6-C20, a borohydride group or an allyl group;

[0013] m = 1 or 2; n = 0, 1 or 2.

[0014] In the method for preparing an ethylene-styrene random copolymer according to the present invention, among them, the derivative of the cyclopentadienyl having the structure of formula II is that at least one hydrogen on the cyclopentadienyl having the structure of formula II is substituted by an alkyl group, the derivative of the indenyl having the structure of formula III is that at least one hydrogen on the indenyl having the structure of formula III is substituted by an alkyl group, and the derivative of the fluorenyl having the structure of formula IV is that at least one hydrogen on the fluorenyl having the structure of formula IV is substituted by an alkyl group.

[0015] In the method for preparing an ethylene-styrene random copolymer according to the present invention, among them, the Ln is scandium (Sc), yttrium (Y), lanthanum (La), neodymium (Nd), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) or lutetium (Lu).

[0016] In the method for preparing an ethylene-styrene random copolymer according to the present invention, among them, R 2 , R 3Independently selected from hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl, 2,6-dimethylphenyl, 4-methylphenyl, mesityl, 2,6-diisopropylphenyl, 2,4,6-triisopropylphenyl or 2,6-di-tert-butylphenyl; said R 4 is an alkyl group having 1 to 10 carbon atoms, a silyl group having 1 to 10 carbon atoms, an alkylamino group having 1 to 10 carbon atoms, an arylamino group having 6 to 10 carbon atoms, a borohydride group or an allyl group.

[0017] The method for preparing an ethylene-styrene random copolymer according to the present invention, wherein said R 4 is an allyl group, a trimethylsilylmethyl group, -BH 4 , an anilino group.

[0018] The method for preparing an ethylene-styrene random copolymer according to the present invention, wherein the catalyst further comprises an organic borate and an alkylaluminum compound, or the catalyst further comprises an aluminoxane compound and an alkylaluminum compound, or the catalyst further comprises an aluminoxane compound; the molar ratio of the organic borate to the rare earth complex is (0.5 to 2):1, the molar ratio of the alkylaluminum to the rare earth complex is (1 to 500):1, and the molar ratio of the aluminoxane to the rare earth complex is (1 to 2000):1.

[0019] The method for preparing an ethylene-styrene random copolymer according to the present invention, wherein the molar ratio of styrene to the rare earth complex is (300 to 30000):1, and the pressure of ethylene is 0.1 to 10 MPa.

[0020] The method for preparing an ethylene-styrene random copolymer according to the present invention, wherein the copolymerization reaction is carried out in an organic solvent, and the initial concentration of ethylene in the organic solvent is 0.1 to 5.0 mol / L; the temperature of the copolymerization reaction is 20 to 130 °C, and the time is 0.15 hours to 7 days.

[0021] The method for preparing an ethylene-styrene random copolymer according to the present invention, wherein the catalyst further comprises an organic borate and an alkylaluminum compound, and the rare earth complex, the organic borate and the alkylaluminum compound are first mixed uniformly in an organic solvent, and then used to catalyze the copolymerization reaction of ethylene and styrene.

[0022] The method for preparing an ethylene-styrene random copolymer according to the present invention, wherein the organic borate is [Ph 3 C][B(C 6 F 5 ) 4 , [Ph 3 C][BPh 4 , [PhNMe 2 H][BPh 4, [PhNMe 2 H][B(C 6 F 5 ) 4 , BPh 3 or B(C 6 F 5 ) 3 .

[0023] Advantages of the present invention:

[0024] Under the catalysis of a catalyst having a specific rare earth complex, ethylene and styrene are directly copolymerized to obtain a random copolymer, and the insertion rate of styrene in the polymer is relatively high. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is the nuclear magnetic resonance carbon spectrum of the ethylene-styrene random copolymer prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0026] The technical solutions of the present invention are described in detail below. The following embodiments are implemented on the premise of the technical solutions of the present invention, and the detailed implementation processes are given. However, the protection scope of the present invention is not limited to the following embodiments. For the structures or experimental methods without specific conditions noted in the following embodiments, they are usually in accordance with conventional conditions.

[0027] For all raw materials of the present invention, there is no particular limitation on their sources, and they can be purchased on the market or prepared according to the conventional methods well-known to those skilled in the art. The grades or abbreviations of the raw materials of the present invention are all conventional grades or abbreviations in the art, and each grade and abbreviation is clear and definite in the field of its relevant uses. Those skilled in the art can purchase or prepare them from the market according to the grades, abbreviations and corresponding uses.

[0028] For all raw materials of the present invention, there is no particular limitation on their purity. The present invention preferably uses analytical pure or the conventional purity requirements in the field of polyolefin materials preparation.

[0029] The present invention has no particular limitation on the molecular weight of the copolymer, and the conventional molecular weight well-known to those skilled in the art can be used. Those skilled in the art can select according to the actual application situation, product performance and quality requirements.

[0030] The present invention provides a method for preparing an ethylene-styrene copolymer. The copolymerization reaction is carried out using ethylene and styrene as raw materials, and the catalyst includes a rare earth complex. The rare earth complex has the following structure of formula I:

[0031]

[0032] Wherein, R1 It is a cyclopentadienyl and its derivatives with the structure of formula II, an indenyl and its derivatives with the structure of formula III, or a fluorenyl and its derivatives with the structure of formula IV;

[0033]

[0034] R 2 、R 3 are independently selected from a hydrocarbon group or hydrogen, and the hydrocarbon group has 1 - 20 carbons;

[0035] Ln is a rare earth metal, S is sulfur, E is C, Si or Ge, Y is tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether or toluene; R 4 is an alkyl group with C1 - C20, a silyl group with C1 - C20, an alkylamino group with C1 - C20, an arylamino group with C1 - C20, a borohydride group or an allyl group;

[0036] m = 1 or 2; n = 0, 1 or 2.

[0037] The catalyst of the present invention includes a specific rare earth complex. Under the catalysis of the catalyst of the present invention, ethylene and styrene directly carry out a copolymerization reaction to obtain a random copolymer, and the insertion rate of styrene in this polymer is relatively high.

[0038] Among them, R 1 is a cyclopentadienyl with the structure of formula II, a derivative of the cyclopentadienyl with the structure of formula II, an indenyl with the structure of formula III, a derivative of the indenyl with the structure of formula III, a fluorenyl with the structure of formula IV or a derivative of the fluorenyl with the structure of formula IV. In one embodiment, the derivative of the cyclopentadienyl with the structure of formula II is that at least one hydrogen on the cyclopentadienyl with the structure of formula II is substituted by an alkyl group, the derivative of the indenyl with the structure of formula III is that at least one hydrogen on the indenyl with the structure of formula III is substituted by an alkyl group, and the derivative of the fluorenyl with the structure of formula IV is that at least one hydrogen on the fluorenyl with the structure of formula IV is substituted by an alkyl group. Among them, the substituted alkyl group can have 1 - 6 carbons, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, etc. The present invention does not particularly limit the number of alkyl substituents on the structures of formula II, formula III and formula IV, and it can be 1, 2, 3, 4, 5, etc. In another embodiment, R 1 is an indenyl with the structure of formula III, a derivative of the indenyl with the structure of formula III, a fluorenyl with the structure of formula IV or a derivative of the fluorenyl with the structure of formula IV. In yet another embodiment, R 1 is a fluorenyl with the structure of formula IV or a derivative of the fluorenyl with the structure of formula IV. R 1 groups chelate with the rare earth metal.

[0039] In a specific embodiment, R1 is fluorenyl, 2,7 - di - tert - butylfluorenyl, indenyl, 4,7 - dimethylindenyl, 2 - methylindenyl, cyclopentadienyl, tetramethylcyclopentadienyl, 1 - tert - butyl - 2 - trimethylsilylcyclopentadienyl, 1,3 - bis(trimethylsilyl)cyclopentadienyl, methylcyclopentadienyl, tert - butylcyclopentadienyl, trimethylsilylcyclopentadienyl, 1,2 - dimethylcyclopentadienyl, 1,3 - dimethylcyclopentadienyl, 1,2 - diethylcyclopentadienyl, ethylcyclopentadienyl, n - butylcyclopentadienyl, n - octylcyclopentadienyl, tetrahydroindenyl, propylcyclopentadienyl, octahydrofluorenyl, phenylcyclopentadienyl, 1,2 - diphenylcyclopentadienyl, cyclohexylcyclopentadienyl or 2,2′ - biphenylcyclopentadienyl, more preferably fluorenyl, 2,7 - di - tert - butylfluorenyl, indenyl, 4,7 - dimethylindenyl, 2 - methylindenyl, cyclopentadienyl, tetramethylcyclopentadienyl, methylcyclopentadienyl, tert - butylcyclopentadienyl, trimethylsilylcyclopentadienyl, 1,2 - diphenylcyclopentadienyl, 2,2′ - biphenylcyclopentadienyl, and most preferably fluorenyl, indenyl, 2 - methylindenyl, cyclopentadienyl, tetramethylcyclopentadienyl, 1,2 - diphenylcyclopentadienyl or 2,2′ - biphenylcyclopentadienyl.

[0040] Wherein, E is C, Si or Ge, which is bonded to the carbon adjacent to sulfur in the five - membered heterocycle and R respectively 1 bonded, and m represents the number of E, for example, m = 1 or 2.

[0041] Wherein, R 2 , R 3 is bonded to E, and R 2 , R 3 are independently selected from hydrocarbon groups or hydrogen, and the hydrocarbon group has 1 - 20 carbons. In one embodiment, R 2 , R 3 are independently selected from hydrogen, methyl, ethyl, isopropyl, tert - butyl, phenyl, 2,6 - dimethylphenyl, 4 - methylphenyl, mesityl, 2,6 - diisopropylphenyl, 2,4,6 - triisopropylphenyl or 2,6 - di - tert - butylphenyl. In another embodiment, R 2 , R 3 are independently selected from hydrogen, methyl, ethyl, isopropyl, tert - butyl, phenyl, 2,6 - dimethylphenyl, 2,6 - diisopropylphenyl, 2,4,6 - triisopropylphenyl or 2,6 - di - tert - butylphenyl. In yet another embodiment, R 2 , R 3 are independently selected from hydrogen, methyl, ethyl, isopropyl, tert - butyl, phenyl, 2,6 - dimethylphenyl, 2,6 - diisopropylphenyl or 2,6 - di - tert - butylphenyl.

[0042] Among them, Ln is a rare earth metal, which is scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) or lutetium (Lu). In one embodiment, Ln is scandium (Sc), yttrium (Y), lanthanum (La), neodymium (Nd), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) or lutetium (Lu). In another embodiment, Ln is scandium (Sc), yttrium (Y), lanthanum (La), neodymium (Nd), gadolinium (Gd), erbium (Er), thulium (Tm) or lutetium (Lu).

[0043] In the present invention, Ln respectively forms coordination bonds with S and R in the five-membered heterocycle 1 , R 4 and Y. More specifically, Ln in the present invention forms coordination bonds with two R 4 groups respectively. Y is tetrahydrofuran, diethyl ether, dimethoxyethane or toluene. In one embodiment, Y is tetrahydrofuran; n represents the number of Y groups. For example, n = 0, 1 or 2. In one embodiment, n is 0 or 1. In the present invention, Y is a solvent molecule coordinated on the rare earth complex.

[0044] R 4 is an alkyl group with 1 to 20 carbon atoms, a silyl group with 1 to 20 carbon atoms, an alkylamino group with 1 to 20 carbon atoms, an arylamino group with 6 to 20 carbon atoms, a borohydride group or an allyl group. In one embodiment, R 4 is an alkyl group with 1 to 10 carbon atoms, a silyl group with 1 to 10 carbon atoms, an alkylamino group with 1 to 10 carbon atoms, an arylamino group with 6 to 20 carbon atoms, a borohydride group or an allyl group. In one embodiment, R4 is selected from an alkyl group with 1 to 16 carbon atoms, a silyl group with 4 to 16 carbon atoms, an alkylamino group with 2 to 16 carbon atoms, a silylamino group with 4 to 20 carbon atoms, an arylamino group with 6 to 20 carbon atoms, an allyl group with 3 to 10 carbon atoms, a benzyl group with 7 to 20 carbon atoms, a borohydride group, a tetramethylaluminum group, hydrogen, chlorine, bromine or iodine. Two R 4Each is independently preferably selected from an alkyl group having 1 to 10 carbon atoms, a silyl group having 4 to 12 carbon atoms, an alkylamino group having 2 to 10 carbon atoms, a silylamino group having 4 to 12 carbon atoms, an arylamino group having 6 to 16 carbon atoms, an allyl group having 3 to 9 carbon atoms, a benzyl group having 7 to 12 carbon atoms, a borohydride group, a tetramethylaluminum group, hydrogen, chlorine, bromine or iodine, more preferably each is independently selected from trimethylsilylmethylene, bis(trimethylsilyl)methylene, allyl, 2-methylallyl, 1,3-bis(trimethylsilyl)allyl, hexamethyldisilazanyl, tetramethylsilylamino, methyl, benzyl, 4-methylbenzyl, 2-N,N'-dimethylbenzyl, tetramethylaluminum group, borohydride group, hydrogen, chlorine or bromine, still more preferably each is independently selected from trimethylsilylmethylene, allyl, 2-methylallyl, hexamethyldisilazanyl, tetramethylsilylamino, benzyl, 4-methylbenzyl, 2-N,N'-dimethylbenzyl, tetramethylaluminum group or chlorine, and most preferably is trimethylsilylmethylene, allyl, 2-methylallyl, tetramethylsilylamino, benzyl, 4-methylbenzyl or 2-N,N'-dimethylbenzyl. In another embodiment, R 4 is allyl, trimethylsilylmethyl, -BH 4 , or arylamino.

[0045] The present invention has no other special restrictions on the selection of the above substituents. R 1 to R 4 can all be independently selected, where R 2 and R 3 can be the same or different. The present invention has no special restrictions on the cyclopentadienyl and its derivatives having the structure of formula II, the indenyl and its derivatives having the structure of formula III, and the fluorenyl and its derivatives having the structure of formula IV. The cyclopentadienyl and its derivatives, indenyl and its derivatives, or fluorenyl and its derivatives well-known to those skilled in the art can be used.

[0046] The present invention has no special restrictions on the selection and combination of the substituents in the rare earth complex having the structure of formula I. The selection and combination methods well-known to those skilled in the art can be used. The present invention preferably uses rare earth complexes having formulas 1 to 20, where the complexes shown in formulas 1 to 12 are rare earth complexes in which R 4 is an alkylsilyl or arylamino group, the complexes shown in formulas 13 to 17 are rare earth complexes in which R 4 is an allyl group, and the complexes shown in formulas 18 to 20 are rare earth complexes in which R 4 is a borohydride group.

[0047]

[0048] Accordingly, the present invention provides a rare earth complex, in which the rare earth chelates with a five-membered heterocycle and is connected to an initiating group, and is an eta5-coordinated rare earth complex with a constrained geometry structure. Therefore, the rare earth complex of the present invention has a sulfur-rare earth metal coordination bond that is rare in the field of rare earth catalysts; the chelating five-membered heterocycle has a strong electron-donating ability, which can change the electronic effect of the central metal, increase the Lewis acidity of the metal ion, and thus increase the activity of the rare earth complex as a catalyst; and due to the eta5 coordination mode of the cyclopentadienyl ring (cyclopentadienyl and its derivatives, indenyl and its derivatives, and fluorenyl and its derivatives) in the rare earth complex, and there is also a sulfur atom coordinated to the central metal, which has a restricting effect on the space of the central metal. Therefore, the rare earth complex containing sulfur coordination of the present invention catalyzes the copolymerization of styrene and ethylene, and the resulting polymer has a high insertion rate of polyethylene.

[0049] The present invention also provides a preparation method of the above rare earth complex, which includes the following steps:

[0050] Step 1, reacting a compound of formula V with an organolithium compound to obtain a compound of formula VI;

[0051] Step 2, reacting the compound of formula VI with a rare earth halide to obtain a compound of formula VII;

[0052] Step 3, subjecting the compound of formula VII to an alkylation reaction to obtain a rare earth complex of formula I;

[0053]

[0054] The present invention has already described in detail the meanings of R 1 , R 2 , R 3 , R 4 , Ln, S, E, Y, m, and n above, and will not be elaborated here.

[0055] The preparation method of the rare earth complex of the present invention is carried out in an anhydrous and oxygen-free environment. The present invention has no special restrictions on the anhydrous and oxygen-free conditions, and the anhydrous and oxygen-free conditions well-known to those skilled in the art can be used. In the present invention, it is preferably to use the method of introducing dry inert gas or nitrogen to obtain the anhydrous and oxygen-free conditions, and more preferably to introduce nitrogen to obtain the anhydrous and oxygen-free conditions.

[0056] In one embodiment, the organolithium compound is alkyllithium, lithium silylamide, alkyllithium amide, alkyllithium arylamide, alkylsilyl alkyllithium, alkylthio aryllithium, lithium tetrahydroborate, alkylphosphino aryllithium, etc. Further, the organolithium compound is methyllithium, ethyllithium, propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, lithium silylamide, dimethylaminolithium, diethylaminolithium, dipropylaminolithium, N,N-dimethylaminophenyl lithium, trimethylsilylmethyllithium, bis(trimethylsilyl)methyllithium, o-methylthiophenyl lithium, o-dimethylphosphinophenyl lithium, lithium tetrahydroborate, methoxylithium, ethoxylithium, isopropoxylithium, n-propoxylithium, n-butoxylithium, sec-butoxylithium or tert-butoxylithium; preferably n-butyl, N,N-dimethylaminophenyl, trimethylsilylmethyl, bis(trimethylsilyl)methyl; most preferably n-butyl. The molar ratio of the organolithium compound to the compound of formula V is (1 to 1.2):1; preferably (1:1.15):1.

[0057] In step 1, the reaction of the compound of formula V with the organolithium compound is carried out in an organic solvent. The specific reaction steps are, for example: under anhydrous and anaerobic conditions, the compound of formula V, the organolithium compound and the organic solvent are mixed and then reacted to obtain the compound of formula VI. The ratio of the volume of the organic solvent to the amount of substance of the compound of formula V is (4 to 6) L:1 mol, preferably (4.5 to 5.5) L:1 mol; the reaction time is 0.8 to 1.5 hours, preferably 0.8 to 1.2 hours, most preferably 1 hour; the reaction temperature is -78°C to 40°C, preferably -50°C to 30°C, most preferably -10°C to 20°C.

[0058] The present invention does not particularly limit the organic solvent used in step 1, and any organic solvent well-known to those skilled in the art can be used. Preferably, it is tetrahydrofuran, pyridine, n-hexane, diethyl ether, toluene or ethylene glycol dimethyl ether, and more preferably tetrahydrofuran.

[0059] In one embodiment, in order to stabilize the reaction temperature, it is preferred to first dissolve the organolithium compound in a second organic solvent. In order for the ligand to better participate in the reaction, it is preferred to first dissolve the ligand of the compound of formula V in an organic solvent, and then add the second organic solvent containing the organolithium compound for reaction, and finally obtain the compound of formula VI; wherein, in the second organic solvent containing the organolithium compound, the concentration of the organolithium compound is preferably 1.0 to 2.0 mol / L, more preferably 1.2 to 1.8 mol / L.

[0060] The present invention does not particularly limit the second organic solvent, and any organic solvent well-known to those skilled in the art can be used. Preferably, it is tetrahydrofuran, pyridine, n-hexane, diethyl ether, toluene or ethylene glycol dimethyl ether, and more preferably n-hexane; in the present invention, the organic solvent and the second organic solvent can be the same or different, and there is no special limitation.

[0061] The present invention has no particular limitation on the source of the compound of formula V, and it can be prepared by synthetic methods well-known to those skilled in the art. Preferably, it is prepared with reference to the following literature: (J. Chen, Y. Li, S. Li, J. Liu, F. Zheng, Z. Zhang, Q. Xu, Green Chemistry, 2017, 19(3): 623 - 628).

[0062] Step 2 is: reacting the compound of formula VI with a rare earth halide to obtain the compound of formula VII.

[0063] Among them, the rare earth halide is a compound formed by the combination of a rare earth atom and a halogen atom. The rare earth atom is scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) or lutetium (Lu). In one embodiment, the rare earth atom is scandium (Sc), yttrium (Y), lanthanum (La), neodymium (Nd), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) or lutetium (Lu). In another embodiment, the rare earth atom is scandium (Sc), yttrium (Y), lanthanum (La), neodymium (Nd), gadolinium (Gd), erbium (Er), thulium (Tm) or lutetium (Lu). The present invention has no particular limitation on the rare earth halide, and any rare earth halide well-known to those skilled in the art can be used. Preferably, it is rare earth trichloride. The molar ratio of the rare earth halide to the compound of formula V is (1 - 1.2):1, preferably (1.05 - 1.15):1. The reaction time of step 2 is 3 - 5 hours, preferably 3.5 - 4.5 hours, and most preferably 4 hours.

[0064] Step 3 is: carrying out an alkylation reaction on the compound of formula VII and the compound of formula VIII to obtain the rare earth complex of formula I.

[0065] In one embodiment, the compound of formula VIII in the present invention includes the structure LiR 4 or MgBrR 4 ; In another embodiment, the compound of formula VIII in the present invention is a rare earth compound containing an alkyl group, an allyl group-containing compound or a borohydride group-containing compound; in the rare earth compound containing an alkyl group, the alkyl group is preferably an alkyl group having 1 - 20 carbon atoms, a silyl group having 1 - 20 carbon atoms, or an alkylamino group having 1 - 20 carbon atoms; the allyl group-containing compound is preferably an allyl Grignard reagent or an allyl derivative Grignard reagent, and among them, the allyl Grignard reagent is more preferably C 3 H 5 MgCl, and the allyl derivative Grignard reagent is preferably C 3 H n R 5 MgCl, where n is preferably 3 or 4, R5 Preferably an aliphatic group having 1 to 20 carbon atoms, an alicyclic group having 1 to 20 carbon atoms, phenyl or a substituted phenyl group, and the substituted phenyl group is preferably a phenyl group substituted by an aliphatic group having 1 to 20 carbon atoms, an alicyclic group having 1 to 20 carbon atoms and an aromatic group; the boron hydride group-containing compound is, for example, sodium borohydride.

[0066] The molar ratio of the compound of formula VIII to the compound of formula V in the present invention is (2 to 2.4):1, preferably (2 to 2.2):1; the temperature of the reaction in step 3 is preferably room temperature, for example 20 - 30 °C; the reaction time is preferably 10 to 14 hours, more preferably 11 to 13 hours, and most preferably 12 hours.

[0067] After the reaction in step 3 of the present invention is completed, it is preferred to remove the solvent and extract and concentrate with toluene to obtain a rare earth complex having the structure of formula I; the present invention has no particular limitation on the method for removing the solvent, and any method well-known to those skilled in the art for removing the solvent can be used; the present invention has no particular limitation on the conditions for toluene extraction, and any conditions well-known to those skilled in the art for toluene extraction can be used; the present invention has no particular limitation on the method for concentration, and any method well-known to those skilled in the art for concentration can be used.

[0068] The rare earth complex of the present invention can be prepared by other methods, and the present invention does not make a particular limitation. For example, the compound of formula V, a rare earth compound and an organic solvent are mixed and reacted to obtain a rare earth complex of formula I;

[0069] Among them, the structure of the rare earth compound is Ln(R 4 ) 2 (Y) n ;

[0070] Ln is a rare earth metal, Y is tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether or toluene; R 4 is an alkyl group having 1 to 20 carbon atoms, a silyl group having 1 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, a boron hydride group or an allyl group; n = 0, 1 or 2.

[0071] The reaction temperature of the compound of formula V and the rare earth compound is 20 - 30 °C, the reaction time is 10 to 14 h, and the molar ratio of the rare earth compound to the compound of formula V is 2 to 2.4:1.

[0072] In one embodiment, the catalyst of the present invention further comprises an organic borate and an alkylaluminum compound, or the catalyst further comprises an aluminoxane compound and an alkylaluminum compound, or the catalyst further comprises an aluminoxane compound. The catalyst of the present invention is preferably a rare earth catalyst composition composed of a rare earth complex, an organic borate and an alkylaluminum.

[0073] The alkylaluminum compound is preferably an alkylaluminum, a hydrocarbylaluminum hydride or a hydrocarbylaluminum chloride, more preferably trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-n-butylaluminum, triisopropylaluminum, triisobutylaluminum, tripentylaluminum, trihexylaluminum, tricyclohexylaluminum, trioctylaluminum, triphenylaluminum, tri-p-tolylaluminum, tribenzylaluminum, ethyldibenzylaluminum, ethyldi-p-tolylaluminum, diethylbenzylaluminum, dimethylaluminum hydride, diethylaluminum hydride, di-n-propylaluminum hydride, di-n-butylaluminum hydride, diisopropylaluminum hydride, diisobutylaluminum hydride, dipentylaluminum hydride, dihexylaluminum hydride, dicyclohexylaluminum hydride, dioctylaluminum hydride, diphenylaluminum hydride, di-p-tolylaluminum hydride, dibenzylaluminum hydride, ethylbenzylaluminum hydride, ethyl-p-tolylaluminum hydride, dimethylaluminum chloride, diethylaluminum chloride, di-n-propylaluminum chloride, di-n-butylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum chloride, dipentylaluminum chloride, dihexylaluminum chloride, dicyclohexylaluminum chloride, dioctylaluminum chloride, diphenylaluminum chloride, di-p-tolylaluminum chloride, dibenzylaluminum chloride, ethylbenzylaluminum chloride, ethyl-p-tolylaluminum chloride, methylaluminoxane, ethylaluminoxane, n-propylaluminoxane or n-butylaluminoxane, and most preferably methylaluminum, trimethylaluminum, triethylaluminum, triisobutylaluminum, methylaluminoxane, diisobutylaluminum hydride, diethylaluminum chloride.

[0074] The organic borate is preferably: [Ph 3 C][B(C 6 F 5 ) 4 , [Ph 3 C][BPh 4 , [PhNMe 2 H][BPh 4 , [PhNMe 2 H][B(C 6 F 5 ) 4 , BPh 3 or B(C 6 F 5 ) 3 , more preferably [Ph 3 C][B(C 6 F 5 ) 4 , BPh 3 or [Ph 3 C][BPh 4 .

[0075] The aluminoxane compound is preferably an alkylaluminoxane, more preferably methylaluminoxane, dry methylaluminoxane or modified methylaluminoxane, and most preferably methylaluminoxane or modified methylaluminoxane; the present invention has no particular limitation on the dry methylaluminoxane, and the definition of dry methylaluminoxane well-known to those skilled in the art can be used, that is, methylaluminoxane does not contain methylaluminum; the present invention has no particular limitation on the modified methylaluminoxane, and the definition of modified methylaluminoxane well-known to those skilled in the art can be used, that is, methylaluminoxane contains isobutylaluminum.

[0076] In one embodiment, the molar ratio of the organic borate salt to the rare earth complex is preferably (0.5 - 10.0):1, more preferably (1.0 - 5.0):1, and most preferably (1.0 - 3.0):1. The molar ratio of the alkylaluminum compound to the rare earth complex is preferably (1 - 2000):1, more preferably (1 - 100):1, and most preferably (5 - 50):1. The molar ratio of methylaluminoxane to the rare earth complex is (1 - 2000):1, more preferably (1 - 100):1, and most preferably (5 - 50):1.

[0077] In one embodiment, the molar ratio of styrene to the rare earth complex is (300 - 30000):1, preferably (1000 - 20000):1, more preferably (5000 - 10000):1, and further preferably (7000 - 8000):1. The copolymerization reaction of the present invention is carried out in an organic solvent, and the initial concentration of styrene in the organic solvent is preferably 0.1 - 5.0 mol / L, more preferably 0.33 - 2.0 mol / L, and most preferably 1.0 - 2.0 mol / L (this unit is the ratio of the number of moles of the monomer to the volume of the organic solvent). In the copolymerization reaction, the pressure of ethylene is preferably 0.1 - 10 MPa, more preferably 0.1 - 5 MPa, and most preferably 0.1 - 2 MPa. The temperature of the copolymerization reaction is preferably 20 - 130 °C, more preferably 30 - 110 °C, more preferably 50 - 80 °C, and the time of the copolymerization reaction is preferably 0.15 hours - 7 days, more preferably 0.2 - 6 hours.

[0078] The present invention has no particular limitation on the organic solvent, and an organic solvent well-known to those skilled in the art for such reactions can be used. It is preferably one or more of saturated alkane organic solvents, aromatic organic solvents, halogenated aromatic organic solvents, and cycloalkane organic solvents. More preferably, it is a saturated alkane organic solvent, an aromatic organic solvent, a halogenated aromatic organic solvent, or a cycloalkane organic solvent. Further preferably, it is a hydrocarbon solvent having 5 to 8 carbon atoms. More preferably, it is one or more of n-hexane, n-heptane, petroleum ether, cyclohexane, decalin, benzene, ethylbenzene, toluene, xylene, chlorobenzene, dichlorobenzene, bromobenzene, and dichloromethane. It can also be n-hexane, decalin, petroleum ether, cyclohexane, toluene, or chlorobenzene, or one or more of n-hexane, decalin, petroleum ether, cyclohexane, and toluene.

[0079] In one embodiment, each component of the catalyst of the present invention is first mixed uniformly in an organic solvent, and then ethylene and styrene are catalytically copolymerized. In another embodiment, the copolymerization reaction of ethylene and styrene of the present invention is carried out under anhydrous and anaerobic conditions. The method for generating the anhydrous and anaerobic conditions of the present invention preferably includes introducing a protective gas. The present invention has no particular limitation on the protective gas, and a protective gas well-known to those skilled in the art can be used. Those skilled in the art can select according to the actual production situation, product performance, and quality requirements. The protective gas of the present invention preferably includes nitrogen and / or inert gas. More preferably, it is nitrogen or argon, and most preferably, it is nitrogen.

[0080] To further improve the yield and performance of the final product and complete and optimize the process route, the preparation steps of ethylene-styrene of the present invention are specifically preferably as follows:

[0081] 1) Dissolve each component of the catalyst in an organic solvent to obtain a catalyst solution;

[0082] 2) Under the condition of a protective gas, carry out a copolymerization reaction of ethylene and styrene monomers in the catalyst solution obtained in the above step, and obtain an ethylene-styrene copolymer after post-treatment.

[0083] The present invention has no particular limitation on the post-treatment method, and a post-treatment method well-known to those skilled in the art can be used. Those skilled in the art can select according to the actual production situation, product performance, and quality requirements. The post-treatment of the present invention preferably includes separation and drying, and more preferably, sedimentation and drying.

[0084] The above preparation steps of the present invention can be specifically as follows:

[0085] First, mix a rare earth complex, an organic boron salt, and an alkyl aluminum compound uniformly in an organic solvent to obtain a catalyst solution.

[0086] Then, take the catalyst solution obtained in the above steps and add it to a polymerization container filled with styrene monomer and saturated with ethylene, which has been treated under anhydrous and anaerobic conditions, to carry out a polymerization reaction. After the reaction is completed, add a hydrochloric acid ethanol solution with a volume concentration of 10% to terminate the polymerization reaction. Pour the reaction solution into ethanol for precipitation to obtain a copolymer. Finally, place the obtained copolymer in a vacuum drying oven for drying to obtain an ethylene-styrene copolymer with a constant dry weight.

[0087] In one embodiment, in the catalyst solution of the present invention, the molar concentration of the rare earth complex is preferably 0.2 mmol / L to 2.0 mmol / L, more preferably 0.5 mmol / L to 1.8 mmol / L.

[0088] The ethylene-styrene copolymer obtained by the method of the present invention is a random copolymer, for example, having the following structural fragments:

[0089]

[0090] Among them, a is a positive integer greater than zero. The present invention does not particularly limit the value range of a, and the conventional value range well-known to those skilled in the art can be used. Those skilled in the art can select according to the actual application situation, product performance, and quality requirements. In the present invention, a is preferably a positive integer greater than zero, more specifically preferably a positive integer greater than zero and less than or equal to 100, more specifically preferably a positive integer greater than or equal to 1 and less than or equal to 10, and more specifically preferably a positive integer greater than or equal to 1 and less than or equal to 4.

[0091] In the ethylene-styrene copolymer of the present invention, the content of the styrene structural unit is between 5 mol% and 70 mol%, that is, the insertion rate of styrene is 10% - 70%. The styrene structural units are randomly distributed in the copolymer, and the melting point is between 110 - 130 °C.

[0092] To further understand the present invention, the following is a detailed description of the preparation method of the ethylene-styrene copolymer provided by the present invention in combination with examples.

[0093] Preparation of rare earth complexes shown in Formula 1 - Formula 20

[0094] Preparation of rare earth complex shown in Formula 1

[0095] Under anhydrous and anaerobic conditions, a ligand (0.5 mmol) shown in Formula V where R 1 is indenyl, E is C, R 2 , R 3 are hydrogen, and m = 1 is reacted with Y(CH 2 SiMe 3 ) 2 (THF) 2Stir for 12 hours in tetrahydrofuran, and remove the solvent to obtain a rare earth complex (0.22 g) with the structure of Formula 1.

[0096] Preparation of the rare earth complex shown in Formula 2

[0097] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) where R shown in Formula V 1 is indenyl, E is C, R 2 、R 3 are hydrogen, and m = 1 is reacted with Lu(CH 2 SiMe 3 ) 2 (THF) 2 (0.5 mmol) by the method for preparing the rare earth complex shown in Formula 1 to obtain a rare earth complex (0.26 g) with the structure of Formula 2.

[0098] Preparation of the rare earth complex shown in Formula 3

[0099] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) where R shown in Formula V 1 is indenyl, E is C, R 2 、R 3 are hydrogen, and m = 1 is reacted with Er(CH 2 SiMe 3 ) 2 (THF) 2 (0.5 mmol) by the method for preparing the rare earth complex shown in Formula 1 to obtain a rare earth complex (0.26 g) with the structure of Formula 3.

[0100] Preparation of the rare earth complex shown in Formula 4

[0101] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) where R shown in Formula V 1 is indenyl, E is C, R 2 、R 3 are hydrogen, and m = 1 is reacted with Gd(CH 2 SiMe 3 ) 2 (THF) 2 (0.5 mmol) by the method for preparing the rare earth complex shown in Formula 1 to obtain a rare earth complex (0.23 g, Yield: 75%) with the structure of Formula 4.

[0102] Preparation of the rare earth complex shown in Formula 5

[0103] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) where R shown in Formula V 1 is fluorenyl, E is C, R 2 、R 3 are hydrogen, and m = 1 is reacted with Sc(CH2 SiMe 3 ) 2 (THF) 2 (0.5 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 1, a rare earth complex (0.25 g) with the structure of Formula 5 was obtained.

[0104] Preparation of the rare earth complex shown in Formula 6

[0105] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is fluorenyl, E is C, R 2 , R 3 is hydrogen, and m = 1 was reacted with Lu(CH 2 SiMe 3 ) 2 (THF) 2 (0.5 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 1, a rare earth complex (0.27 g) with the structure of Formula 6 was obtained.

[0106] Preparation of the rare earth complex shown in Formula 7

[0107] Under anhydrous and anaerobic conditions, a tetrahydrofuran solution of the ligand (0.5 mmol) of Formula V where R 1 is indenyl, E is C, R 2 , R 3 is methyl, and m = 1 was reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution) at 0 °C for 1 hour to obtain the lithium salt of the first reaction mixture ligand; at room temperature, the tetrahydrofuran solution of the above lithium salt was added dropwise to a tetrahydrofuran suspension of LaCl 3 (0.5 mmol), and the reaction was carried out for 4 hours to obtain the second reaction mixture rare earth chloride; Li(o-CH 2 C 6 H 4 NMe 2 )(1.0 mmol) was added and reacted for 12 hours. After removing the solvent and extracting and concentrating with toluene, a rare earth complex (0.24 g) with the structure of Formula 7 was obtained.

[0108] Preparation of the rare earth complex shown in Formula 8

[0109] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is indenyl, E is C, R 2 , R 3 is methyl, and m = 1 was reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), LaCl 3 (0.5 mmol), Li(o-CH 2C 6 H 4 NMe 2 (1.0 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 7, a rare earth complex (0.27 g) with the structure of Formula 8 was obtained.

[0110] Preparation of the rare earth complex shown in Formula 9

[0111] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is 3,6 - di - tert - butylfluorenyl, E is C, R 2 , R 3 is hydrogen, and m = 1 was reacted with n - butyllithium (0.32 mL, 1.6 M n - hexane solution), LaCl 3 (0.5 mmol), Li(o - CH 2 C 6 H 4 NMe 2 (1.0 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 7, a rare earth complex (0.25 g) with the structure of Formula 9 was obtained.

[0112] Preparation of the rare earth complex shown in Formula 10

[0113] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is fluorenyl, E is Si, R 2 , R 3 is methyl, and m = 1 was reacted with n - butyllithium (0.32 mL, 1.6 M n - hexane solution), YCl 3 (0.5 mmol), Li(o - CH 2 C 6 H 4 NMe 2 (1.0 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 7, a rare earth complex (0.24 g) with the structure of Formula 10 was obtained.

[0114] Preparation of the rare earth complex shown in Formula 11

[0115] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is fluorenyl, E is C, R 2 , R 3 is hydrogen, and m = 1 was reacted with n - butyllithium (0.32 mL, 1.6 M n - hexane solution), ScCl 3 (0.5 mmol), Li(o - CH 2 C 6 H 4 NMe 2(1.0 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 7, a rare earth complex with the structure of Formula 11 (0.25 g) was obtained.

[0116] Preparation of the rare earth complex shown in Formula 12

[0117] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is fluorenyl, E is C, R 2 , R 3 is hydrogen, and m = 1 was reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), LuCl 3 (0.5 mmol), Li(o-CH 2 C 6 H 4 NMe 2 )(1.0 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 7, a rare earth complex with the structure of Formula 12 (0.27 g) was obtained.

[0118] Preparation of the rare earth complex shown in Formula 13

[0119] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is fluorenyl, E is C, R 2 , R 3 is hydrogen, and m = 1 was reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), YCl 3 (0.5 mmol), CH 2 CHCH 2 MgBr(1.0 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 7, a rare earth complex with the structure of Formula 13 (0.16 g, Yield: 69%) was obtained.

[0120] Preparation of the rare earth complex shown in Formula 14

[0121] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is indenyl, E is C, R 2 , R 3 is hydrogen, and m = 1 was reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), GdCl 3 (0.5 mmol), CH 2 CHCH 2 MgBr(1.0 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 7, a rare earth complex with the structure of Formula 14 (0.11 g) was obtained.

[0122] Preparation of the rare earth complex shown in Formula 15

[0123] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of formula V where R 1 is indenyl, E is C, R 2 , R 3 is hydrogen, and m = 1 is reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), LaCl 3 (0.5 mmol), CH 2 CHCH 2 MgBr (1.0 mmol) using the method for preparing the rare earth complex of formula 7 to obtain the rare earth complex (0.19 g) with the structure of formula 15.

[0124] Preparation of the rare earth complex of formula 16

[0125] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of formula V where R 1 is indenyl, E is C, R 2 , R 3 is hydrogen, and m = 1 is reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), ScCl 3 (0.5 mmol), CH 2 CHCH 2 MgBr (1.0 mmol) using the method for preparing the rare earth complex of formula 7 to obtain the rare earth complex (0.17 g) with the structure of formula 16.

[0126] Preparation of the rare earth complex of formula 17

[0127] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of formula V where R 1 is indenyl, E is C, R2, R3 are hydrogen, and m = 1 is reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), LuCl 3 (0.5 mmol), CH 2 CHCH 2 MgBr (1.0 mmol) using the method for preparing the rare earth complex of formula 7 to obtain the rare earth complex (0.20 g) with the structure of formula 17.

[0128] Preparation of the rare earth complex of formula 18

[0129] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of formula V where R 1 is fluorenyl, E is C, R 2 , R 3 is hydrogen, and m = 1 is reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), YCl 3 (0.5 mmol), NaBH 4(1.0 mmol) Using the method for preparing the rare earth complex shown in Preparation Formula 7, a rare earth complex with the structure of Formula 18 (0.12 g) was obtained.

[0130] Preparation of the Rare Earth Complex Shown in Formula 19

[0131] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is tetramethylcyclopentadienyl, E is C, R 2 , R 3 is hydrogen, and m = 1 was reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), TbCl 3 (0.5 mmol), and NaBH 4 (1.0 mmol) using the method for preparing the rare earth complex shown in Preparation Formula 7, and a rare earth complex with the structure of Formula 19 (0.08 g) was obtained.

[0132] Preparation of the Rare Earth Complex Shown in Formula 20

[0133] Under anhydrous and anaerobic conditions, the ligand (0.5 mmol) of Formula V where R 1 is tetramethylcyclopentadienyl, E is C, R 2 , R 3 is hydrogen, and m = 1 was reacted with n-butyllithium (0.32 mL, 1.6 M n-hexane solution), LaCl 3 (0.5 mmol), and NaBH 4 (1.0 mmol) using the method for preparing the rare earth complex shown in Preparation Formula 7, and a rare earth complex with the structure of Formula 20 (0.16 g) was obtained.

[0134] Preparation of the Catalyst Composition:

[0135] Preparation of Catalyst Composition 1

[0136] At 25 °C, 10 μmol of the rare earth complex shown in Formula 1, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 50 μmol of triisobutylaluminum, and toluene solvent were added to a 25 ml polymerization vessel that had been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 2.0 mmol·L –1 , and the reaction was carried out for 2 minutes to obtain Catalyst Composition 1.

[0137] Preparation of Catalyst Composition 2

[0138] At 25 °C, 10 μmol of the rare earth complex shown in Formula 2, 10 μmol of [Ph3 C][B(C 6 F 5 ) 4 , 100 μmol of triisobutylaluminum and toluene solvent, the concentration of the rare earth complex in the catalyst composition is 0.67 mmol·L –1 . React for 2 minutes to obtain catalyst composition 2.

[0139] Preparation of catalyst composition 3

[0140] At 0 °C, add 10 μmol of the rare earth complex shown in Formula 2, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 100 μmol of triisobutylaluminum and toluene solvent, the concentration of the rare earth complex in the catalyst composition is 0.67 mmol·L –1 . React for 2 minutes to obtain catalyst composition 3.

[0141] Preparation of catalyst composition 4

[0142] At -60 °C, add 10 μmol of the rare earth complex shown in Formula 2, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 100 μmol of triisobutylaluminum and toluene solvent, the concentration of the rare earth complex in the catalyst composition is 0.67 mmol·L –1 . React for 2 minutes to obtain catalyst composition 4.

[0143] Preparation of catalyst composition 5

[0144] At 40 °C, add 10 μmol of the rare earth complex shown in Formula 2, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 100 μmol of triisobutylaluminum and toluene solvent, the concentration of the rare earth complex in the catalyst composition is 0.67 mmol·L –1 . React for 2 minutes to obtain catalyst composition 5.

[0145] Preparation of catalyst composition 6

[0146] At 80 °C, 10 μmol of the rare earth complex shown in Formula 2, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 100 μmol of triisobutylaluminum and toluene solvent were added to a 25 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.67 mmol·L –1 . After reacting for 2 minutes, catalyst composition 6 was obtained.

[0147] Preparation of Catalyst Composition 7

[0148] At 25 °C, 10 μmol of the rare earth complex shown in Formula 2, 20 μmol of dried methylaluminoxane, 100 μmol of trimethylaluminum and xylene solvent were added to a 25 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 1.0 mmol·L –1 . After reacting for 2 minutes, catalyst composition 7 was obtained.

[0149] Preparation of Catalyst Composition 8

[0150] At 25 °C, 10 μmol of the rare earth complex shown in Formula 3, 10 μmol of [PhNHMe 2 [B(C 6 F 5 ) 4 , 200 μmol of triethylaluminum and toluene solvent were added to a 25 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 1.0 mmol·L –1 . After reacting for 2 minutes, catalyst composition 8 was obtained.

[0151] Preparation of Catalyst Composition 9

[0152] At -40 °C, 10 μmol of the rare earth complex shown in Formula 4, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 100 μmol of triisobutylaluminum and toluene solvent were added to a 50 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 1.0 mmol·L –1 . After reacting for 2 minutes, catalyst composition 9 was obtained.

[0153] Preparation of Catalyst Composition 10

[0154] At 25 °C, 10 μmol of the rare earth complex shown in Formula 5, 100 μmol of methylaluminoxane, 100 μmol of triethylaluminum, and toluene solvent were added to a 250 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 1.0 mmol·L –1 , and the reaction was carried out for 2 minutes to obtain catalyst composition 10.

[0155] Preparation of catalyst composition 11

[0156] At 25 °C, 10 μmol of the rare earth complex shown in Formula 5, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 100 μmol of triisobutylaluminum, and toluene solvent were added to a 50 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.5 mmol·L –1 , and the reaction was carried out for 2 minutes to obtain catalyst composition 11.

[0157] Preparation of catalyst composition 12

[0158] At 60 °C, 10 μmol of the rare earth complex shown in Formula 6, 10 μmol of [PhNHMe 2 [B(C 6 F 5 ) 4 , 1 mmol of triisobutylaluminum, and toluene solvent were added to a 25 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 1.0 mmol·L –1 , and the reaction was carried out for 2 minutes to obtain catalyst composition 12.

[0159] Preparation of catalyst composition 13

[0160] At 0 °C, 10 μmol of the rare earth complex shown in Formula 7, 20 μmol of methylaluminoxane, and pentane solvent were added to a 100 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.2 mmol·L –1 , and the reaction was carried out for 2 minutes to obtain catalyst composition 13.

[0161] Preparation of catalyst composition 14

[0162] At 25 °C, 10 μmol of the rare earth complex shown in Formula 8, 1000 μmol of methylaluminoxane, 300 μmol of trimethylaluminum, and hexane solvent were added to a 50 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.2 mmol·L –1, React for 2 minutes to obtain catalyst composition 14.

[0163] Preparation of catalyst composition 15

[0164] At 40 °C, add 10 μmol of the rare earth complex shown in Formula 9, 50 μmol of trimethylaluminoxane, 10 mmol of triisobutylaluminum, and hexane solvent to a 50 ml polymerization vessel that has been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.25 mmol·L –1 , React for 2 minutes to obtain catalyst composition 15.

[0165] Preparation of catalyst composition 16

[0166] At 25 °C, add 10 μmol of the rare earth complex shown in Formula 10, 10 μmol of [Ph 3 C][BPh 4 , 10 mmol of triisobutylaluminum, and hexane solvent to a 50 ml polymerization vessel that has been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.2 mmol·L –1 , React for 2 minutes to obtain catalyst composition 16.

[0167] Preparation of catalyst composition 17

[0168] At 0 °C, add 10 μmol of the rare earth complex shown in Formula 11, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 5 mmol of triisobutylaluminum, and hexane solvent to a 50 ml polymerization vessel that has been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.25 mmol·L –1 , React for 2 minutes to obtain catalyst composition 17.

[0169] Preparation of catalyst composition 18

[0170] At 25 °C, add 10 μmol of the rare earth complex shown in Formula 12, 10 mmol of methylaluminoxane, 500 μmol of triethylaluminum, and xylene solvent to a 50 ml polymerization vessel that has been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.33 mmol·L –1 , React for 2 minutes to obtain catalyst composition 18.

[0171] Preparation of catalyst composition 19

[0172] At 60 °C, add 10 μmol of the rare earth complex shown in Formula 13, 20 μmol of [Ph3 C][B(C 6 F 5 ) 4 , 100 μmol of triisobutylaluminum and hexane solvent, the concentration of the rare earth complex in the catalyst composition is 0.2 mmol·L –1 , react for 2 minutes to obtain catalyst composition 19.

[0173] Preparation of catalyst composition 20

[0174] At 0 °C, add 10 μmol of the rare earth complex shown in Formula 14, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 500 μmol of triisobutylaluminum and xylene solvent to a 50 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.25 mmol·L –1 , react for 2 minutes to obtain catalyst composition 20.

[0175] Preparation of catalyst composition 21

[0176] At 40 °C, add 10 μmol of the rare earth complex shown in Formula 15, 10 μmol of [PhNHMe 2 [B(C 6 F 5 ) 4 , 1 mmol of trimethylaluminum and toluene solvent to a 50 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.33 mmol·L –1 , react for 2 minutes to obtain catalyst composition 21.

[0177] Preparation of catalyst composition 22

[0178] At 25 °C, add 10 μmol of the rare earth complex shown in Formula 16, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 10 mmol of triisobutylaluminum and hexane solvent to a 25 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.25 mmol·L –1 , react for 2 minutes to obtain catalyst composition 22.

[0179] Preparation of catalyst composition 23

[0180] At -60 °C, 10 μmol of the rare earth complex shown in Formula 17, 10 μmol of [Ph 3 C][BPh 4 , 1 mmol of triisobutylaluminum and hexane solvent were added to a 50 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.25 mmol·L –1 . After reacting for 2 minutes, catalyst composition 23 was obtained.

[0181] Preparation of catalyst composition 24

[0182] At 80 °C, 10 μmol of the rare earth complex shown in Formula 17, 10 μmol of [Ph 3 C][BPh 4 , 1 mmol of triisobutylaluminum and toluene solvent were added to a 100 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.2 mmol·L –1 . After reacting for 2 minutes, catalyst composition 24 was obtained.

[0183] Preparation of catalyst composition 25

[0184] At 0 °C, 10 μmol of the rare earth complex shown in Formula 18, 100 μmol of modified methylaluminoxane, 5 mmol of trimethylaluminum and pentane solvent were added to a 50 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.2 mmol·L –1 . After reacting for 2 minutes, catalyst composition 25 was obtained.

[0185] Preparation of catalyst composition 26

[0186] At 25 °C, 10 μmol of the rare earth complex shown in Formula 18, 100 μmol of modified methylaluminoxane, 5 mmol of trimethylaluminum and hexane solvent were added to a 50 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.2 mmol·L –1 . After reacting for 2 minutes, catalyst composition 26 was obtained.

[0187] Preparation of catalyst composition 27

[0188] At 80 °C, 10 μmol of the rare earth complex shown in Formula 18, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 20 μmol of diisobutylaluminum hydride and toluene solvent were added to a 25 ml polymerization vessel treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.67 mmol·L–1 , react for 2 minutes to obtain catalyst composition 27.

[0189] Preparation of catalyst composition 28

[0190] At 60 °C, add 10 μmol of the rare earth complex shown in Formula 18, 10 μmol of BPh 3 , 200 μmol of diethylaluminum chloride, and toluene solvent into a 25 ml polymerization container that has been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.5 mmol·L –1 , react for 2 minutes to obtain catalyst composition 28.

[0191] Preparation of catalyst composition 29

[0192] At 25 °C, add 10 μmol of the rare earth complex shown in Formula 19, 20 μmol of [Ph 3 C][BPh 4 , 200 μmol of diethylaluminum chloride, and hexane solvent into a 25 ml polymerization container that has been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.28 mmol·L –1 , react for 2 minutes to obtain catalyst composition 29.

[0193] Preparation of catalyst composition 30

[0194] At 40 °C, add 10 μmol of the rare earth complex shown in Formula 20, 100 μmol of dry methylaluminoxane, 500 μmol of diisobutylaluminum hydride, and toluene solvent into a 25 ml polymerization container that has been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.5 mmol·L –1 , react for 2 minutes to obtain catalyst composition 30.

[0195] Preparation of catalyst composition 31

[0196] At 0 °C, add 10 μmol of the rare earth complex shown in Formula 20, 10 μmol of [Ph 3 C][B(C 6 F 5 ) 4 , 500 μmol of triisobutylaluminum, and pentane solvent into a 50 ml polymerization container that has been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition is 0.2 mmol·L –1 , react for 2 minutes to obtain catalyst composition 31.

[0197] Preparation of catalyst composition 32

[0198] At -60 °C, 10 μmol of the rare earth complex shown in Formula 20, 10 μmol of [PhNHMe 2 [BPh 4 , 2 mmol of trimethylaluminum and pentane solvent were added to a 50 ml polymerization container that had been treated with anhydrous and anaerobic conditions. The concentration of the rare earth complex in the catalyst composition was 0.25 mmol·L –1 . The reaction was carried out for 2 minutes to obtain catalyst composition 32.

[0199] Examples of ethylene and styrene copolymerization:

[0200] Example 1

[0201] In a glove box, 5 ml of the toluene solution of catalyst combination 1 was taken and placed in an ampoule. Toluene (30 mL) and styrene monomer (20 mmol) were placed in a reaction flask with a magnetic stirrer. The ampoule was connected to the reaction flask through a rubber tube. The reaction flask was taken out of the glove box and placed in an oil bath at 40 °C. The atmosphere in the reaction flask was replaced with ethylene three times, and then the catalyst solution in the ampoule was quickly added to the toluene solution of styrene. Ethylene was continuously introduced throughout the polymerization process (for example, 4 bar). After reaching the specified polymerization time of 2 hours, acidified ethanol was added to the reaction flask to terminate the polymerization. The above mixture was poured into ethanol for precipitation. The polymer was separated by filtration, placed in an oven at 20 °C, and dried under reduced pressure to a constant weight to obtain sample 1.

[0202] Examples 2 - 32: The experimental procedures for this series of examples were the same as those in Example 1. The polymerization reaction conditions, the changing conditions of the catalytic system, and the polymerization results are shown in Table 1.

[0203] Table 1

[0204]

[0205]

[0206] From the polymerization data of Examples 1 - 32, it can be concluded that when the catalyst combination provided by the present invention catalyzes the polymerization reaction of ethylene and styrene, the styrene insertion amount ranges between 30% and 5%. The number-average molecular weight of the random copolymer prepared by the present invention is in the range of 0.2 - 101,000, the molecular weight distribution is relatively narrow (1.21 - 1.52), and the melting point is about 120 °C.

[0207] Of course, the present invention can also have many other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing an ethylene-styrene random copolymer, characterized in that, ethylene and styrene are used as raw materials for copolymerization reaction, and the catalyst includes a rare earth complex, and the rare earth complex has the following structural formula I: Among them, R 1 is a cyclopentadienyl and its derivatives having the structure of formula II, an indenyl and its derivatives having the structure of formula III, or a fluorenyl and its derivatives having the structure of formula IV; R 2 、R 3 are independently selected from a hydrocarbyl group or hydrogen, said hydrocarbyl group having 1 to 20 carbons; Ln is a rare earth metal, S is sulfur, E is C, Si or Ge, Y is tetrahydrofuran, diethyl ether, 1,2-dimethoxyethane or toluene; R 4 is an alkyl group having 1 to 20 carbon atoms, a silyl group having 1 to 20 carbon atoms, an alkylamino group having 1 to 20 carbon atoms, an arylamino group having 6 to 20 carbon atoms, a borohydride group or an allyl group; m = 1 or 2; n = 0, 1 or 2.

2. The method for preparing an ethylene-styrene random copolymer according to claim 1, characterized in that, the derivative of the cyclopentadienyl group of structural formula II is that at least one hydrogen on the cyclopentadienyl group of structural formula II is substituted by an alkyl group, the derivative of the indenyl group of structural formula III is that at least one hydrogen on the indenyl group of structural formula III is substituted by an alkyl group, and the derivative of the fluorenyl group of structural formula IV is that at least one hydrogen on the fluorenyl group of structural formula IV is substituted by an alkyl group.

3. The method for preparing an ethylene-styrene random copolymer according to claim 1, characterized in that, the Ln is scandium (Sc), yttrium (Y), lanthanum (La), neodymium (Nd), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb) or lutetium (Lu).

4. The method for preparing an ethylene-styrene random copolymer according to claim 1, characterized in that, R 2 、R 3 are independently selected from hydrogen, methyl, ethyl, isopropyl, tert-butyl, phenyl, 2,6-dimethylphenyl, 4-methylphenyl, mesityl, 2,6-diisopropylphenyl, 2,4,6-triisopropylphenyl or 2,6-di-tert-butylphenyl; said R 4 is an alkyl group having 1 to 10 carbon atoms, a silyl group having 1 to 10 carbon atoms, an alkylamino group having 1 to 10 carbon atoms, an arylamino group having 6 to 20 carbon atoms, a borohydride group or an allyl group.

5. The method for preparing an ethylene-styrene random copolymer according to claim 4, characterized in that, The said R 4 is allyl, trimethylsilylmethyl, -BH 4 , anilino.

6. The method for preparing an ethylene-styrene random copolymer according to claim 1, characterized in that, the catalyst further includes an organic borate and an alkyl aluminum compound, or the catalyst further includes an aluminoxane compound and an alkyl aluminum compound, or the catalyst further includes an aluminoxane compound; the molar ratio of the organic borate to the rare earth complex is (0.5 - 2):1, the molar ratio of the alkyl aluminum to the rare earth complex is (1 - 500):1, and the molar ratio of the aluminoxane to the rare earth complex is (1 - 2000):

1.

7. The method for preparing an ethylene-styrene random copolymer according to claim 1, characterized in that, the molar ratio of the styrene to the rare earth complex is (300 - 30000):1, and the pressure of the ethylene is 0.1 - 10 MPa.

8. The method for preparing an ethylene-styrene random copolymer according to claim 1, characterized in that, the copolymerization reaction is carried out in an organic solvent, and the initial concentration of ethylene in the organic solvent is 0.1 - 5.0 mol / L; the temperature of the copolymerization reaction is 20 - 130 °C, and the time is 0.15 hours - 7 days.

9. The method for preparing an ethylene-styrene random copolymer according to claim 6, characterized in that, the catalyst further includes an organic borate and an alkyl aluminum compound, and the rare earth complex, the organic borate and the alkyl aluminum compound are first mixed evenly in an organic solvent, and then used to catalyze the copolymerization reaction of ethylene and styrene.

10. The method for preparing an ethylene-styrene random copolymer according to claim 6, characterized in that, The organic borate is [Ph 3 C][B(C 6 F 5 ) 4 , [Ph 3 C][BPh 4 , [PhNMe 2 H][BPh 4 , [PhNMe 2 H][B(C 6 F 5 ) 4 , BPh 3 or B(C 6 F 5 ) 3 .

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