Bimetal compound as well as preparation method and application thereof

Abstract

The invention provides a bimetallic compound as well as a preparation method and application thereof. The bimetallic compound provided by the invention is designed by comprising Cr, group IVB bimetallic and a specific ligand; according to the present invention, the catalyst has the excellent catalytic activity, the excellent high-temperature stability and the high alpha-olefin insertion rate in the ethylene polymerization reaction to prepare the polyolefin elastomer, and the polyolefin elastomer obtained through catalysis has advantages of high molecular weight and high 1-octene insertion rate, and can achieve the good rigid-tough balance and the good low-temperature cold brittleness resistance; good application prospects are realized.

Description

Technical Field

[0001] The invention belongs to the field of olefin polymerization and relates to a bimetallic compound and a preparation method and application thereof. Background Art

[0002] There are many types of polyolefin materials, which are widely used in people's daily lives. However, with the development of society, traditional polyolefin materials can no longer meet people's daily needs. Polyolefin materials are developing in the direction of functionality. Among them, polyolefin elastomers (POE) are a type of elastomeric materials mainly obtained by copolymerization of ethylene and α-olefins (such as 1-butene, 1-hexene, 1-octene, etc.). They combine the high elasticity of rubber and the processing properties of polyolefin plastics. They have been widely used in the automotive field, packaging material field, wire and cable field, and medical device field.

[0003] At present, the process of industrial production of POE mainly involves adding monomer ethylene and comonomer α-olefin into the reactor, adding a certain amount of diluent to prevent polymer sticking to the reactor, catalyzing the copolymerization of ethylene and α-olefin by the main metal catalyst under the activation of the cocatalyst, and also introducing hydrogen as a molecular weight regulator to regulate the molecular weight of the polymer. After the copolymerization is completed, the polymer, diluent and monomer are separated. However, the currently reported methods all require the addition of high-carbon α-olefin as a comonomer, and the cost of such monomers is relatively high, resulting in high costs for industrial production of polyolefin elastomers.

[0004] Therefore, it is of great significance to avoid the use of high-carbon α-olefins and prepare polyolefin elastomers with excellent performance using only ethylene as a monomer. Summary of the invention

[0005] The present invention provides a bimetallic compound and a preparation method thereof and application in the field of olefin polymerization. The bimetallic compound provided by the present invention includes Cr and a group IVB bimetal as well as a specific ligand design, so that the bimetallic compound exhibits excellent catalytic activity, high temperature stability and high alpha-olefin insertion rate in the reaction of preparing a polyolefin elastomer by ethylene polymerization. The polyolefin elastomer obtained by catalysis has the advantages of high molecular weight and high 1-octene insertion rate, can achieve better rigidity-toughness balance and low-temperature cold brittleness resistance, and has good application prospects.

[0006] The first aspect of the present invention provides a bimetallic compound having a structure shown in Formula I:

[0007]

[0008] In Formula I, M is selected from the group consisting of metals of IVB; R1 to R 14Each is independently selected from one of C1~C20 alkyl, C3~C20 cycloalkyl, C1~C20 alkoxy, C3~C20 cycloalkyloxy, C1~C20 alkylamino, C3~C20 cycloalkylamino, hydrogen, halogen, aryl, aryloxy, and arylamino; X is selected from one of methyl, chlorine, dimethylamino, and benzyl; Ar1, Ar2, and Ar3 are each independently selected from one of phenyl, phenyl substituted with C1~C6 alkyl, phenyl substituted with C1~C6 alkoxy, naphthyl, and anthracenyl.

[0009] The bimetallic compound as described above, wherein R1 to R 14 Each is independently selected from one of hydrogen, C1-C6 alkyl, C3-C10 cycloalkyl, diphenylmethyl, halogen, dibenzosuberyl, fluorenyl, indenyl and anthracenyl;

[0010] Preferably, R1~R 14 Each is independently selected from hydrogen, tert-butyl, isopropyl, diphenylmethyl and halogen.

[0011] A second aspect of the present invention provides a method for preparing the bimetallic compound as described above, comprising the following steps:

[0012] The compound represented by formula II is subjected to a first complexation reaction with MX4 to obtain a compound represented by formula III;

[0013] The compound represented by formula III is subjected to a second complexation reaction with chromium trichloride to obtain the compound represented by formula I;

[0014]

[0015] In Formula II and Formula III, R1 to R 14 The definitions of Ar1, Ar2, Ar3, X1, X2 and M are the same as those of R1 to R2 in the compound of Formula I. 14 , Ar1, Ar2, Ar3, X and M have the same meanings.

[0016] The third aspect of the present invention provides an olefin polymerization catalyst, comprising a main catalyst and a co-catalyst, wherein the main catalyst comprises the bimetallic compound as described above.

[0017] The olefin polymerization catalyst as described above, wherein the cocatalyst comprises one or more of tripentafluorophenyl boron, triphenylcarbonium tetrakis(pentafluorophenyl)borate, tetrakis(pentafluorophenyl)boric acid-methyldi-(octadecyl)ammonium salt, aluminoxane, alkylaluminum and alkylaluminum chloride.

[0018] The olefin polymerization catalyst as described above, wherein the aluminoxane comprises one or more of methylaluminoxane, ethylaluminoxane, and isobutylaluminoxane;

[0019] And / or, the alkyl aluminum includes one or more of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, and tri-n-hexyl aluminum;

[0020] And / or, the alkylaluminum chloride includes one or more of diethylaluminum monochloride, triethylaluminum trichloride, diethylaluminum sesquichloride, and ethylaluminum dichloride.

[0021] In the olefin polymerization catalyst as described above, the molar ratio of the metal aluminum in the co-catalyst to the metal M and Cr in the main catalyst is Al / (Cr+M) (1-5000):1, preferably (300-2000):1.

[0022] The fourth aspect of the present invention provides a method for preparing a polyolefin elastomer, comprising: using the olefin polymerization catalyst provided by the third aspect of the present invention to catalyze the polymerization reaction of ethylene monomer to obtain a polyethylene elastomer.

[0023] The preparation method as described above, wherein the polymerization reaction temperature is 0 to 250°C, the pressure is 0.1 to 5 MPa, and the time is 2 to 120 min;

[0024] Preferably, the polymerization reaction is carried out at a temperature of 140 to 220° C., a pressure of 1 to 5 MPa, and a time of 10 to 60 min.

[0025] In the preparation method as described above, the solvent of the polymerization reaction includes one or more of toluene, hexane, heptane, Isopar E, and methylcyclohexane.

[0026] The implementation of the present invention has at least the following advantages:

[0027] 1) The present invention provides a bimetallic compound having a Group IVB metal and Cr, wherein the Group IVB metal has good copolymerization activity of ethylene and α-olefins, and the metal Cr has good ethylene oligomerization activity. In the ethylene polymerization reaction, the metal Cr active center in the compound can promote the oligomerization of ethylene to obtain α-olefins such as 1-butene, 1-hexene, and 1-octene, and the active center of the Group IV metal is conducive to promoting the copolymerization of the generated α-olefin and ethylene, thereby obtaining a polyolefin elastomer with α-olefin insertion. In addition, the present invention also designs a specific ligand structure around the bimetallic active centers of the Group IVB metal and Cr, so that the metal M and the metal Cr active centers have a suitable distance, which is conducive to the diffusion of the oligomer formed near Cr to the vicinity of the M metal active center to participate in the copolymerization with ethylene, so that the rates of the oligomerization reaction and the copolymerization reaction reach a higher balance, which is conducive to the insertion of the oligomer. The rigid structures of the pyridine ring and the substituted benzene ring in the ligand can not only utilize their rigid structures to enhance the stability of the bimetallic compound and enable the bimetallic compound to maintain good activity in high-temperature solution polymerization, but also regulate the electron cloud density of the metal active center through electronic effects and steric hindrance effects, thereby enhancing the catalytic activity of the bimetallic catalyst.

[0028] 2) The olefin polymerization catalyst provided by the present invention, whose main catalyst includes the above-mentioned bimetallic compound with good thermal stability, high α-olefin insertion activity and polymerization activity, therefore the olefin polymerization catalyst is applied to the reaction of preparing high molecular weight, highly branched polyolefin elastomer using ethylene as raw material and exhibits excellent catalytic activity and thermal stability.

[0029] 3) The preparation method of the polyolefin elastomer provided by the present invention adopts an olefin polymerization catalyst with high catalytic activity, high α-olefin insertion selectivity and high stability to catalyze the polymerization reaction of ethylene, so the prepared polyolefin elastomer has the advantages of high branching and high molecular weight. The 1-octene insertion rate of the prepared polyolefin elastomer is as high as more than 40%, showing excellent mechanical properties and resistance to low-temperature brittleness. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Definitions and Explanations of Terms :

[0032] Unless otherwise explained, the meaning of all scientific and technological terms herein is the same as that generally understood by those skilled in the art. It should be understood that the above brief description and the detailed description below are exemplary and are only used for explanation, and are not intended to limit the subject matter of the present application. In the present application, the term "including" and other forms, such as "comprising", "containing" and "containing" are not restrictive.

[0033] The term "IVB metal" refers to metals located in Group IVB of the periodic table, including titanium (Ti), zirconium (Zr), hafnium (Hf), and the like.

[0034] The term "C1-C20 alkyl" refers to a straight or branched saturated hydrocarbon group having 1 to 20 carbon atoms, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, sec-butyl, pentyl, neopentyl, hexyl, heptyl, nonyl, decyl, etc.

[0035] The term "C3-20 cycloalkyl" refers to a non-aromatic cyclic hydrocarbon group having 3 to 20 ring carbon atoms and zero heteroatoms, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl and the like.

[0036] The term "C1-C20 alkoxy group" refers to a group consisting of an alkyl group and an oxygen atom having 1 to 20 carbon atoms, for example, methoxy, ethoxy, propoxy, butoxy and the like.

[0037] The term "C3-C20 cycloalkoxy" refers to a group formed by a cycloalkyl group consisting of 3 to 20 carbon atoms connected to an oxygen atom, for example, cyclopropyloxy, cyclobutyloxy, cyclopentyloxy, cyclohexyloxy, cycloheptyloxy, cyclooctyloxy, and the like.

[0038] The term "C1-C20 alkylamino" refers to a group formed by an alkyl group consisting of 1 to 20 carbon atoms connected to an amino group, for example, methylamino, ethylamino, propylamino, butylamino, pentylamino, hexylamino and the like.

[0039] The term "C3-C20 cycloalkylamino" refers to a group formed by a cycloalkyl group consisting of 3 to 20 carbon atoms connected to an amino group, for example, cyclopropylamino, cyclobutylamino, cyclopentylamino, cyclohexylamino and the like.

[0040] The term "halogen" refers to fluorine, chlorine, bromine and iodine.

[0041] The term "aryl" refers to a group satisfying a 4n+2 aromatic ring system, preferably a monocyclic, bicyclic or tricyclic aryl, such as phenyl, biphenyl, indenyl, naphthyl, fluorenyl, anthracenyl, etc. The aryl group may also be optionally substituted by one or more substituents to form different substituted phenyl groups. The substituents may be alkyl, alkoxy, cycloalkyl, halogen, etc.

[0042] The term "aryloxy" refers to a group formed by connecting an aryl group to an oxygen atom, such as a phenoxy group. The hydrogen atoms on the aromatic ring may also be replaced by other substituents to form different substituted aryloxy groups. Other substituents may be alkyl, alkoxy, cycloalkyl, halogen, etc.

[0043] The term "arylamino" refers to a group formed by connecting an aryl group to an amino group, such as phenylamino. The hydrogen atoms on the aromatic ring may also be substituted by other substituents to form different substituted arylamino groups. Other substituents may be alkyl, alkoxy, cycloalkyl, halogen, etc.

[0044] Polyolefin elastomer (POE) is a polyolefin material obtained by copolymerization of ethylene and α-olefin. Since the molecular chain includes both polyethylene crystalline segments and amorphous regions formed by random copolymerization of α-olefin and ethylene, POE has both the thermoplasticity of plastics and the high elasticity of rubber. Its unique molecular structure and physical and chemical properties give polyolefin elastomers excellent mechanical properties and anti-aging properties. At present, the preparation process of POE is mainly based on the solution coordination polymerization process of ethylene and α-olefin catalyzed by metallocene catalysts. However, the cost of α-olefin is relatively high, resulting in high costs for industrial production of polyolefin elastomers. It is of great significance to avoid the use of high-carbon α-olefins and prepare polyolefin elastomers using only ethylene as a monomer.

[0045] In view of the above problems, the prior art generally uses a special catalyst to regulate the homopolymerization and copolymerization reaction activity of ethylene to obtain a polyethylene elastomer with a certain branching and a higher molecular weight. The catalyst conventionally used in this type of reaction is an α-diimine nickel / palladium complex. This type of complex has a unique "chain walking" polymerization mechanism, which can adjust the branching density and branching type in the polymer main chain structure, and can achieve the preparation of highly branched polyethylene elastomers using ethylene as a single monomer. Despite the above advantages, the α-diimine nickel / palladium complex has poor thermal stability at high temperatures, especially the α-diimine nickel catalyst, which is very easy to deactivate at more than 60°C, limiting its industrial application. Therefore, how to design the catalyst structure to obtain a polyolefin elastomer with good thermal stability that can catalyze ethylene to obtain a high degree of branching and high molecular weight is a technical problem to be solved by the present invention.

[0046] Based on this, the first aspect of the present invention is a bimetallic compound having a structure shown in Formula I:

[0047]

[0048] In Formula I, M is selected from the group consisting of metals of IVB; R1 to R 14Each is independently selected from one of C1~C20 alkyl, C3~C20 cycloalkyl, C1~C20 alkoxy, C3~C20 cycloalkyloxy, C1~C20 alkylamino, C3~C20 cycloalkylamino, hydrogen, halogen, aryl, aryloxy, and arylamino; X is selected from one of methyl, chlorine, dimethylamino, and benzyl; Ar1, Ar2, and Ar3 are each independently selected from one of phenyl, phenyl substituted with C1~C6 alkyl, phenyl substituted with C1~C6 alkoxy, naphthyl, and anthracenyl.

[0049] In Formula I, Represents a coordination bond.

[0050] The present invention adopts a specific ligand structure to combine chromium metal with a Group IVB metal to form a bimetallic compound. When catalyzing ethylene polymerization, the Cr metal exhibits excellent ethylene polymerization activity and can promote ethylene polymerization to form 1-butene, 1-hexene, 1-octene and other oligomers; while the Group IVB metal exhibits excellent ethylene homopolymerization and copolymerization activity and can promote the copolymerization of ethylene with the oligomers 1-butene, 1-hexene, 1-octene and other oligomers formed by polymerization, thereby obtaining a polyolefin elastomer material with a high α-olefin insertion rate.

[0051] Wherein, the ligand structure around the IVB group metal and the Cr metal is the key to the catalyst design. The ligand designed by the present invention makes the metal M and the metal Cr active center have a suitable distance, which is conducive to the diffusion of the oligomer formed near the Cr to the M metal activity near the M metal activity and the copolymerization with ethylene, so that the rate of the polymerization reaction and the copolymerization reaction reaches a higher balance, which is conducive to the insertion of the oligomer. Wherein, the M metal is connected to the N on the pyridine ring through a coordination bond, and the pyridine N, as a weak σ-donor, can enhance the electron density of the metal M, and the oxygen atom in the phenoxy group connected to the M metal and the substituent on the benzene ring can also regulate the electron density of the metal M, enhance the catalytic activity of the M metal, and then facilitate the polyolefin elastomer with high molecular weight and high α-olefin insertion rate. In addition, the compound structure shown in Formula I has a large amount of benzene ring structure, while regulating the bimetallic spacing, its rigid structure can also make the compound have good stability, avoid its inactivation under solution conditions and high temperature, and enhance the stability of the bimetallic compound in high temperature solution polymerization.

[0052] It is understandable that the type of substituent is an important factor in regulating the coordination environment, electronic effect and steric effect of bimetallic compounds. 14When each is independently one of hydrogen, C1-C6 alkyl, C3-C10 cycloalkyl, dibenzhydryl, halogen, dibenzocycloheptanyl, fluorenyl, indenyl, and anthracenyl, and more preferably one of hydrogen, tert-butyl, isopropyl, dibenzhydryl, and halogen, the bimetallic compound can exhibit higher catalytic activity during ethylene polymerization, and the polyolefin elastomer can have a higher comonomer insertion rate and a higher molecular weight.

[0053] The second invention of the present invention provides a method for preparing the bimetallic compound as described above, comprising the following steps:

[0054] The compound represented by formula II is subjected to a first complexation reaction with MX4 to obtain a compound represented by formula III;

[0055] The compound represented by formula III is subjected to a second complexation reaction with chromium trichloride to obtain the compound represented by formula I;

[0056]

[0057] In Formula II and Formula III, R1 to R 14 The definitions of Ar1, Ar2, Ar3, X and M are respectively the same as those of R1 to R 14 , Ar1, Ar2, Ar3, X and M have the same meanings.

[0058] Based on the electronic orbital characteristics of the Cr element and the Group IVB elements, the Group IVB metal can preferentially react with the phenolic hydroxyl group in the compound shown in Formula II to obtain the compound shown in Formula III. Subsequently, chromium trichloride is added to coordinate the Cr metal with the P atom in the compound shown in Formula III to obtain the compound shown in Formula I.

[0059] The present invention does not specifically limit the source of the compound represented by formula II, and it can be prepared by reasonable design based on conventional synthesis strategies in organic synthesis and in combination with the properties of different substituents.

[0060] In a specific embodiment, the compound represented by formula II can be prepared by referring to the following synthetic route:

[0061]

[0062] Referring to the above reaction formula, aniline compound a is reacted with hydrogen bromide to obtain ammonium hydrobromide compound b, 2-bromomagnesium-1-methoxybenzene and Ar3MgBr are reacted with phosphorus tribromide to obtain compound c1, and Ar1MgBr and Ar2MgBr are reacted with phosphorus tribromide to obtain compound c2; the prepared compound b, compound c1 and compound c2 are reacted under the action of triethylamine to obtain compound d; then compound d is reacted with n-butyl lithium reagent and triisopropyl borate to convert the bromine atom on compound d into a boronic acid group, thereby completing the preparation of intermediate e.

[0063] Among them, 2-bromomagnesium-1-methoxybenzene, Ar3MgBr, Ar1MgBr, and Ar2MgBr can all be prepared by Grignard reaction.

[0064]

[0065] Referring to the above reaction formula, compound f and compound g are respectively reacted with benzyl chloride to protect the phenolic hydroxyl group, and then the obtained compound h and compound j are reacted with n-butyl lithium reagent and triisopropyl borate to convert the bromine atom on compound d into a boronic acid group to obtain compound k and compound m respectively; then compound k, compound m and compound n are subjected to coupling reaction to obtain compound o; compound o is brominated with liquid bromine to obtain compound p; then compound p is further reacted with n-butyl lithium reagent and triisopropyl borate to convert the bromine atom into a boronic acid group to obtain compound q; compound q is subjected to coupling reaction with p-dibromobenzene to complete the preparation of intermediate r.

[0066]

[0067] Referring to the above reaction formula, intermediate r and intermediate e are subjected to coupling reaction to obtain compound s; compound s is then subjected to catalytic hydrogenation under hydrogen conditions to deprotect the benzyloxy group and reduce it to a phenolic hydroxyl group to prepare the compound represented by formula II.

[0068] Both the first complexation reaction and the second complexation reaction are carried out under the protection of an inert gas, such as a nitrogen atmosphere.

[0069] In order to make the second complex reaction proceed more smoothly, a chromium trichloride tetrahydrofuran complex can be used to provide a chromium trichloride reactant in the reaction. Compared with chromium trichloride, the complex formed by it and tetrahydrofuran has higher solubility in organic solvents, and can also reduce the degradation of chromium trichloride in air and moisture, which is conducive to storage and use.

[0070] The first complexation reaction and the second complexation reaction can be carried out in an organic solvent. Specifically, the solvent for the first complexation reaction can be one or more of n-hexane, toluene, tetrahydrofuran, diethyl ether, butyl ether, isopropyl ether, and cyclopentyl methyl ether; the solvent for the second complexation reaction can be one or more of dichloromethane, tetrahydrofuran, dioxane, and diethyl ether.

[0071] In a specific embodiment, the temperature of the first complex reaction and the second complex reaction can be -80 to 25°C; the time of the first complex reaction and the second complex reaction can be 3 to 16 hours.

[0072] In a specific embodiment, the molar ratio of the compound represented by formula II to MX4 in the first complexation reaction is 1:(0.8-1.2), and the molar ratio of the compound represented by formula III to chromium trichloride in the second complexation reaction is 1:(0.8-1.2).

[0073] After the first complexation reaction and the second complexation reaction are completed, the process of purifying the reaction system is also included.

[0074] After the first complexation reaction is completed, the compound represented by formula III can be precipitated from the reaction solution, so the purification process can be completed by filtering.

[0075] After the second complex reaction is completed, the reaction solution can be concentrated and then allowed to stand at low temperature for crystallization, so that the compound represented by formula I can be fully precipitated, thus completing the purification process.

[0076] The third aspect of the present invention provides an olefin polymerization catalyst, comprising a main catalyst and a co-catalyst, wherein the main catalyst comprises the bimetallic compound provided by the first aspect of the present invention.

[0077] The main function of the main catalyst in the olefin polymerization catalyst is to provide active sites so that the olefin monomers can form metal-carbon bonds at these sites, thereby initiating the polymerization reaction.

[0078] The olefin polymerization catalyst provided by the present invention comprises a main catalyst comprising the above-mentioned bimetallic compound having good thermal stability, high α-olefin insertion activity and polymerization activity. Therefore, the olefin polymerization catalyst is applied to the reaction of preparing high molecular weight, highly branched polyolefin elastomers using ethylene as a raw material and exhibits excellent catalytic activity and thermal stability.

[0079] The role of the co-catalyst in olefin polymerization catalysts is mainly to reduce the metal in the main catalyst from a high oxidation state to a low oxidation state, so that the main catalyst is in an activated state.

[0080] The present invention does not particularly limit the type of the co-catalyst, which can be selected from co-catalysts conventionally used in the field of olefin polymerization, including but not limited to one or more of trispentafluorophenyl boron, triphenylcarbonium tetrakis(pentafluorophenyl)borate, tetrakis(pentafluorophenyl)boric acid-methyldi-(octadecyl)ammonium salt, aluminoxane, alkylaluminum and alkylaluminum chloride.

[0081] Compared with other types of co-catalysts, aluminoxane, alkylaluminum and alkylaluminum chloride have higher thermal stability and hydrolysis resistance, which is beneficial to extend the service life of the catalyst and improve the efficiency of the polymerization reaction.

[0082] Specifically, the aluminoxane includes one or more of methylaluminoxane, ethylaluminoxane, and isobutylaluminoxane; the alkylaluminum includes one or more of trimethylaluminum, triethylaluminum, triisobutylaluminum, and tri-n-hexylaluminum; and the alkylaluminum chloride includes one or more of diethylaluminum monochloride, triethylaluminum trichloride, diethylaluminum sesquichloride, and ethylaluminum dichloride.

[0083] In the present invention, the combination of the main catalyst and the co-catalyst can be reasonably optimized within the above range to achieve precise control of the polymerization reaction activity, selectivity, product molecular weight and its distribution, thereby obtaining a polyolefin elastomer that meets specific requirements.

[0084] The ratio of the main catalyst to the co-catalyst also has a significant effect on the efficiency of the polymerization reaction, the activity stability of the catalyst, and the properties of the generated polymer. An appropriate co-catalyst can activate the main catalyst to the greatest extent and improve its activity. Generally, increasing the amount of the co-catalyst is conducive to the generation of more active centers, which in turn is conducive to increasing the molecular weight of the polymer. However, excessive concentration of the co-catalyst may also lead to the occurrence of chain transfer reactions, resulting in chain termination, which is not conducive to the increase of polymer molecular weight.

[0085] Based on the above considerations, the molar ratio Al / (Cr+M) of the metal aluminum in the co-catalyst and the metal M and Cr in the main catalyst is controlled to be (1-5000):1, preferably (300-2000):1.

[0086] Illustratively, the Al / (Cr+M) molar ratio can be 1:1, 1:300, 1:500, 1:1000, 1:1500, 1:2000, 1:2500, 1:3000, 1:3500, 1:4000, 1:4500, 1:5000 or a range consisting of any two of the above molar ratios.

[0087] In a specific embodiment, when the co-catalyst is selected from boron-containing compounds such as tripentafluorophenyl boron, triphenylcarbonium tetrakis(pentafluorophenyl)borate, tetrakis(pentafluorophenyl)boric acid-methyl di-(octadecyl)ammonium salt, the molar ratio B / (Cr+M) of the B element in the co-catalyst and the M and Cr in the main catalyst is controlled to be (0.5-3):1, more preferably (0.8-1.5):1.

[0088] Illustratively, the B / (Cr+M) molar ratio can be 0.5:1, 1.0:1, 1.5:1, 2.0:1, 2.5:1, 3.0:1, or a range consisting of any two of the foregoing.

[0089] The fourth aspect of the present invention provides a method for preparing a polyolefin elastomer, the method comprising: using the olefin polymerization catalyst provided by the third aspect of the present invention to catalyze the polymerization reaction of ethylene monomer to obtain the polyolefin elastomer.

[0090] In the above preparation method, since an olefin polymerization catalyst with high catalytic activity, high α-olefin insertion selectivity and high stability is used to catalyze the polymerization reaction of ethylene, the prepared polyolefin elastomer has the advantages of high branching and high molecular weight, and exhibits excellent mechanical properties and resistance to low-temperature brittleness.

[0091] As the content of comonomers such as α-olefins in polyolefin elastomers increases, the density and crystallinity of polyolefin elastomers gradually decrease, which is conducive to obtaining lighter and more flexible polyolefin materials. Compared with α-olefins such as 1-butene and 1-hexene, the 1-octene segment is softer and can make the material lighter, and is more suitable for fields that require a higher balance of rigidity and toughness of materials. The preparation method of the present invention can prepare a polyolefin elastomer with a 1-octene insertion rate of more than 40wt% by selecting a specific olefin polymerization catalyst and combining specific polymerization conditions.

[0092] In a specific embodiment, the polymerization reaction temperature is 0-250°C, the pressure is 0.1-5 MPa, and the time is 2-120 min. The polymerization reaction temperature, pressure, time and other factors can be regulated within the above range according to the different requirements such as the catalytic activity of the catalyst and the molecular weight and embedding rate of the product.

[0093] As mentioned above, the bimetallic compound provided by the present invention has good thermal stability and can maintain good catalytic activity in high-temperature solution polymerization. High temperature and high pressure are conducive to increasing the molecular motion speed and solubility of ethylene, so that more ethylene monomers can be dissolved in the reaction medium and the reaction rate is accelerated, which is conducive to the improvement of polymerization reaction products and efficiency, and reduces the production cost of polyolefin elastomers. Therefore, it can be further preferred that the polymerization reaction temperature is 140 to 220°C, the pressure is 1 to 5MPa, and the time is 10 to 60min within the above range, so that the reaction has a higher yield and efficiency.

[0094] Exemplarily, the temperature of the polymerization reaction can be 140°C, 160°C, 180°C, 200°C, 220°C or a range consisting of any two of the values ​​therein; the pressure of the polymerization reaction can be 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa or a range consisting of any two of the values ​​therein; the time of the polymerization reaction can be 10 min, 20 min, 30 min, 40 min, 50 min, 60 min or a range consisting of any two of the values ​​therein.

[0095] The present invention does not specifically limit the solvent for the polymerization reaction, which can be selected from solvents conventionally used in ethylene polymerization reactions, including but not limited to one or more of toluene, hexane, heptane, Isopar E, and methylcyclohexane.

[0096] The present invention is further described below through specific embodiments.

[0097] 1. Reagent Description

[0098] Unless otherwise specified, the raw materials and reagents used in the following examples can be obtained from commercial sources. The specific information is shown in Table 1:

[0099] Table 1

[0100]

[0101]

[0102] 2. Test methods

[0103] A. The compounds in the following examples were analyzed using a nuclear magnetic resonance spectrometer (Brucker ARX-400). 1 HNMR characterization.

[0104] B. The molecular weight of the polymer M w And the molecular weight distribution M w / M nThe results were obtained by PL-GPC220 at 150°C, using three PLgel 10μm MIXED-B columns connected in series and 1,2,4-trichlorobenzene as solvent.

[0105] C. Polymer glass transition temperature T g Measured according to DSC (2000) method;

[0106] D. The polymerization activity of the main catalyst is calculated according to the following formula: polymerization activity = polymer mass / (metal content of catalyst × polymerization time).

[0107] E. The 1-octene insertion rate in the polymer was determined by high temperature elution according to the method in the reference (Macromolecules 1999, 32, 3817). 13 C NMR test shows that high temperature 13 C NMR was measured using 1,1,2,2-tetrachloroethane as solvent at 120°C using a Brucker DMX 300MHz test. 13 C NMR spectrum, the 1-octene insertion rate in the polymer was calculated based on the spectrum;

[0108] F. Tensile strength and elongation at break: measured in accordance with GB / T 1040.1-2006.

[0109] Synthesis example 1

[0110] The synthesis route of compound 1 is as follows:

[0111]

[0112] 1) Under nitrogen atmosphere, 3-bromoaniline (17.21 g, 100 mmol) and hydrogen bromide (8.09 g, 100 mmol) were mixed in 200 ml of diethyl ether, stirred at room temperature for 30 min, and filtered to obtain ammonium hydrobromide salt;

[0113] 2) Under a nitrogen atmosphere, 2-bromomethoxybenzene (18.7 g, 100 mmol) and magnesium chips (2.4 g, 100 mmol) were heated to reflux in 300 ml of tetrahydrofuran for 3 h, filtered, and phosphorus tribromide (13.5 g, 50 mmol) was added dropwise to the filtrate in an ice-water bath, stirred at room temperature for 2 h, filtered, and the solvent was removed from the filtrate under vacuum conditions, 300 ml of triethylamine was added as a solvent, ammonium hydrobromide (12.65 g, 50 mmol) was added, stirred at room temperature for 30 min, filtered, and the filtrate was concentrated under vacuum to obtain a concentrated solution including the intermediate compound 1-a;

[0114] 3) To the concentrated solution including the intermediate compound 1-a, 300 ml of tetrahydrofuran was added as a solvent, 33 mL of a n-hexane solution (1.6 M) of n-butyl lithium was added dropwise to the reaction system under an ice-water bath, and stirred at this temperature for 30 min. Triisopropyl borate (9.4 g, 50 mmol) was added to the reaction system, and stirred at room temperature for 5 h. The solvent was removed under vacuum, and water and ethyl acetate were added for extraction and separation. The separated organic phase was dried and concentrated, and then separated by column chromatography (the eluent was petroleum ether and ethyl acetate in a volume ratio of 1 to 30:1) to obtain 25.5 g of compound 1 with a yield of 81.5%.

[0115] Compound 1 1 H NMR (400MHz, CDCl3): δ7.39(t,4H),7.22-7.11(m,9H),6.96(dd,4H),6.84(dd,1H),6.71(s,1H),4.32(s,2H),3.98(s,13H).

[0116] Synthesis example 2

[0117] The synthesis route of compound 2 is as follows:

[0118]

[0119] 1) Under nitrogen atmosphere, 2-bromophenol (17.3 g, 100 mmol) and benzyl chloride (19 g, 150 mmol) were mixed in 200 mL of acetone, stirred at room temperature for 3 h, the solvent was removed in vacuo, 100 mL of water and 100 mL of ethyl acetate were added, extraction was performed, and the mixture was separated. The ethyl acetate was removed in vacuo to obtain a concentrated solution;

[0120] 2) Add 200 mL of tetrahydrofuran to the concentrated solution of step 1), add 68.8 mL of n-butyl lithium dropwise under an ice-water bath, stir for 30 min, add triisopropyl borate (18.8 g, 100 mmol) under an ice-water bath, react at room temperature for 3 h, remove the solvent in vacuo to obtain a concentrated solution;

[0121] 2) Add 300 mL of ethylene glycol dimethyl ether as solvent to the concentrated solution of step 2), add 2,6-dibromopyridine (11.8 g, 50 mmol), heat to reflux for 4 h, add liquid bromine (4 g, 25 mmol), stir at room temperature for 5 h, remove the solvent under vacuum to obtain a concentrated solution;

[0122] 3) To the concentrated solution of step 3) was added 300 mL of tetrahydrofuran, 34 mL of n-butyl lithium was added dropwise under an ice-water bath, and the mixture was stirred for 30 min. Triisopropyl borate (9.4 g, 50 mmol) was added under an ice-water bath, and the mixture was reacted at room temperature for 3 h. The solvent was removed in vacuo, 100 mL of water was added, 200 mL of ethyl acetate was added, and the liquid was extracted. The separated organic phase was dried and concentrated, and then separated by column chromatography (the eluent was petroleum ether and ethyl acetate in a volume ratio of 1 to 30:1) to obtain 21.7 g of compound 2 with a yield of 87.3%.

[0123] Compound 2 1 H NMR (400MHz, CDCl3): δ8.82(d,2H),7.85(dd,1H),7.41-7.22(m,15H),6.74(d,2H),5.16(s,4H),4.26(s,2H).

[0124] Synthesis example 3

[0125] The synthesis route of compound 3 is as follows:

[0126]

[0127] Under a nitrogen atmosphere, compound 2 (48.7 g, 100 mmol) and p-dibromobenzene (23.6 g, 100 mmol) were mixed in 300 mL of ethylene glycol dimethyl ether and heated to reflux for 5 h. Compound 1 (100 mmol) was added to the reaction system and heated to reflux for 5 h. The solvent was removed in vacuo. 300 mL of ethanol was added. Target carbon was added and H2 was introduced. The reaction was carried out at 4 MPa and 80 ° C for 3 hours. The reaction was filtered and the solvent was removed in vacuo. The concentrate was separated by column chromatography with an eluent (the eluent was petroleum ether and ethyl acetate in a volume ratio of 1 to 30:1) to obtain 82.3 g of compound 3 with a yield of 89.5%.

[0128] Compound 3 1 H NMR (400MHz, CDCl3): δ9.41(s,2H),8.74(dd,1H),8.61(dd,1H),7.92(dd,1H),7.39-7.15(m,29H),6.74(dd,2H),3.83(s,12H).

[0129] Synthesis example 4

[0130] Synthesis of compound Z1

[0131]

[0132] The synthesis steps include:

[0133] Under a nitrogen atmosphere, compound 3 (91.9 g, 100 mmol) and zirconium tetrachloride (24.5 g, 100 mmol) were mixed in 300 mL of n-hexane, stirred at room temperature for 3 hours, filtered, the filter cake was dissolved in 300 mL of dichloromethane, chromium trichloride tetrahydrofuran complex (37.5 g, 100 mmol) was added, stirred at room temperature for 3 hours, the reaction solution was concentrated to 50 mL, and crystallized at -20°C to obtain compound Z1 as a white solid (112.4 g) with a yield of 91%.

[0134] Compound Z1 1 H NMR (400MHz, CDCl3): δ8.74(dd,1H),8.61(dd,1H),7.92(dd,1H),7.39-7.15(m,29H),6.74(dd,2H),3.83(s,12H).

[0135] Synthesis example 5

[0136] Synthesis of compound H1

[0137]

[0138] The synthesis steps were the same as those in Synthesis Example 4, except that zirconium tetrachloride (24.5 g, 100 mmol) was replaced with hafnium tetrachloride (32 g, 100 mmol), to obtain 123.2 g of compound H1, with a yield of 93%.

[0139] Compound H1 1 H NMR (400MHz, CDCl3): δ8.74(dd,1H),8.61(dd,1H),7.92(dd,1H),7.39-7.15(m,29H),6.74(dd,2H),3.83(s,12H).

[0140] Synthesis example 6

[0141] Synthesis of compound T1

[0142]

[0143] The synthesis steps were the same as those in Synthesis Example 4, except that zirconium tetrachloride (24.5 g, 100 mmol) was replaced with titanium tetrachloride (18.9 g, 100 mmol), to obtain 123.2 g of compound H1, with a yield of 93%.

[0144] Compound H1 1H NMR (400MHz, CDCl3): δ8.74(dd,1H),8.61(dd,1H),7.92(dd,1H),7.39-7.15(m,29H),6.74(dd,2H),3.83(s,12H).

[0145] Synthesis Example 7

[0146] Synthesis of compound Z2

[0147]

[0148] The synthesis steps refer to patent CN110698513B.

[0149] Compound Z2 1 H NMR (400MHz, CDCl3): δ8.61(dd,1H),7.64(dd,1H),7.19(t,1H),6.99(dd,2H),6.74 (dd,1H),3.83(q,1H),2.81(hept,2H),2.12(s,6H),1.93-1.88(m,4H),0.91(s,9H).

[0150] The following examples and comparative examples respectively use the compound Z1, compound H1, compound T1 and compound Z2 prepared in the above synthesis examples as main catalysts to catalyze the polymerization of ethylene, and the polymerization steps are as follows:

[0151] A 1L polymerization reactor was dried continuously at 120°C for 6 hrs, evacuated while hot and replaced with N2 gas three times, cooled to room temperature, replaced with ethylene three times, and then 500mL of Isopar-E and MMAO were added thereto. The reactor was heated to 220°C, and 10mL of a toluene solution of the main catalyst (0.1μmol / mL) was added thereto. The ethylene pressure was adjusted to 4MPa and kept constant, and the reaction was stirred vigorously for 30min.

[0152] After the reaction was completed, the temperature was cooled to room temperature and the pressure was released; the reaction solution was neutralized with 5% hydrochloric acid-acidified ethanol solution to obtain a polymer precipitate, which was washed with ethanol and water several times, vacuum-dried to constant weight, and the polymer was weighed.

[0153] When compound Z1, compound H1, and compound T1 are used as the main catalyst, the molar ratio of the Al element in MMAO added during the polymerization to the Cr and M metal in the main catalyst (the M metal in compound Z1 is Zr, the M metal in compound T1 is Hf, and the M metal in compound T1 is Ti) is 2000:1:1. When compound Z2 is used as the main catalyst, the molar ratio of the Al element in MMAO added during the polymerization to the Zr element in the main catalyst is 1000:1.

[0154] The reaction conditions of the above embodiments and comparative examples are shown in Table 2.

[0155] Table 2

[0156]

[0157]

[0158] As can be seen from Table 2, the complex provided by the present invention is selected as the main catalyst, and the catalytic system composed of the co-catalyst exhibits higher catalytic activity, and the obtained polymer has a higher molecular weight, better thermal stability and a higher comonomer insertion rate, and is suitable for high-temperature solution polymerization. In addition, since the 1-octene insertion rate of the polymers of Examples 1 to 3 reaches more than 40wt%, they are softer, so that the polymers have a higher elongation at break.

[0159] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bimetallic compound, characterized in that: It has the structure shown in Formula I: In Formula I, M is selected from the group consisting of metals of IVB; R1 to R 14 Each is independently selected from one of C1~C20 alkyl, C3~C20 cycloalkyl, C1~C20 alkoxy, C3~C20 cycloalkyloxy, C1~C20 alkylamino, C3~C20 cycloalkylamino, hydrogen, halogen, aryl, aryloxy, and arylamino; X is selected from one of methyl, chlorine, dimethylamino, and benzyl; Ar1, Ar2, and Ar3 are each independently selected from one of phenyl, phenyl substituted with C1~C6 alkyl, phenyl substituted with C1~C6 alkoxy, naphthyl, and anthracenyl.

2. The bimetallic compound according to claim 1, characterized in that R1~R 14 Each is independently selected from one of hydrogen, C1-C6 alkyl, C3-C10 cycloalkyl, diphenylmethyl, halogen, dibenzosuberyl, fluorenyl, indenyl and anthracenyl; Preferably, R1~R 14 Each is independently selected from hydrogen, tert-butyl, isopropyl, diphenylmethyl and halogen.

3. A method for preparing a bimetallic compound according to claim 1 or 2, characterized in that: The following steps are involved: The compound represented by formula II is subjected to a first complexation reaction with MX4 to obtain a compound represented by formula III; The compound represented by formula III is subjected to a second complexation reaction with chromium trichloride to obtain the compound represented by formula I; In Formula II and Formula III, R1 to R 14 The definitions of Ar1, Ar2, Ar3, X and M are respectively the same as those of R1 to R 14 , Ar1, Ar2, Ar3, X and M have the same meanings.

4. An olefin polymerization catalyst, comprising a main catalyst and a co-catalyst, characterized in that: The main catalyst comprises the bimetallic compound according to any one of claims 1 or 2.

5. The olefin polymerization catalyst according to claim 4, characterized in that The cocatalyst includes one or more of trispentafluorophenyl boron, triphenylcarbonium tetrakis(pentafluorophenyl)borate, tetrakis(pentafluorophenyl)boric acid-methyldi-(octadecyl)ammonium salt, aluminoxane, alkylaluminum and alkylaluminum chloride.

6. The olefin polymerization catalyst according to claim 5, characterized in that The aluminoxane includes one or more of methylaluminoxane, ethylaluminoxane, and isobutylaluminoxane; And / or, the alkyl aluminum includes one or more of trimethyl aluminum, triethyl aluminum, triisobutyl aluminum, and tri-n-hexyl aluminum; And / or, the alkylaluminum chloride includes one or more of diethylaluminum monochloride, triethylaluminum trichloride, diethylaluminum sesquichloride, and ethylaluminum dichloride.

7. The olefin polymerization catalyst according to claim 6, characterized in that The molar ratio of the metal aluminum in the co-catalyst to the metal M and Cr in the main catalyst is Al / (Cr+M) (1-5000):1, preferably (300-2000):

1.

8. A method for preparing a polyolefin elastomer, characterized in that: include: The polyolefin elastomer is obtained by catalyzing the polymerization reaction of ethylene monomer using the olefin polymerization catalyst described in any one of claims 4 to 7.

9. The preparation method according to claim 8, characterized in that: The polymerization reaction temperature is 0-250°C, the pressure is 0.1-5MPa, and the time is 2-120min; Preferably, the polymerization reaction is carried out at a temperature of 140 to 220° C., a pressure of 1 to 5 MPa, and a time of 10 to 60 min.

10. The preparation method according to claim 8 or 9, characterized in that: The solvent for the polymerization reaction includes one or more of toluene, hexane, heptane, Isopar E, and methylcyclohexane.

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