A method for preparing copolymer of ethylene and alpha-olefin

Abstract

The present invention relates to a method for preparing an ethylene and α-olefin copolymer. Under the protection of nitrogen or inert gas, two monomers of ethylene and α-olefin are dissolved in an inert organic solvent, and then a main catalyst and a co-catalyst are used for catalysis. After coordination copolymerization and post-treatment, the ethylene and α-olefin copolymer is obtained. The main catalyst is a fluorene ring with η 3 The invention discloses a bonding mode coordinated IVB group metal catalyst; a co-catalyst is an aluminum-containing or boron-containing compound; when feeding, the molar fraction of alpha-olefin in the monomer mixture is 1.2 to 2.0 times the insertion rate of alpha-olefin in the ethylene and alpha-olefin copolymer, the insertion rate of alpha-olefin in the ethylene and alpha-olefin copolymer is 3 to 20 mol%, and the number average molecular weight of the ethylene and alpha-olefin copolymer is 20 to 1000 kg / mol. The method of the invention is simple, can make full use of alpha-olefin to reduce costs, and the comprehensive performance of the ethylene and alpha-olefin copolymer is excellent and the chain structure parameters are controllable.

Description

Technical Field

[0001] The invention belongs to the technical field of olefin copolymerization and relates to a method for preparing a copolymer of ethylene and alpha-olefin. Background Art

[0002] Ethylene and α-olefin copolymerization is the main method for preparing linear low-density polyethylene (LLDPE) and polyolefin elastomer (POE). The essential difference between LLDPE and POE lies in the different α-olefin insertion rates. When the α-olefin insertion rate reaches more than 3 mol%, the copolymer will change from LLDPE to POE. The α-olefin insertion rate in POE is generally 3-20 mol%, and the number average molecular weight M n The range is 30-100 kg / mol, with low density, good resistance to low temperature and heat aging, and excellent mechanical properties such as high elasticity, high strength and high elongation at break. Currently, Dow, ExxonMobile, Mitsui, SK, LG, Queo and SABIC have commercialized POE products.

[0003] In the prior art, commercial POE products generally require the solution polymerization process of ethylene and α-olefins catalyzed by early transition metals. Since the polymerization capacity of α-olefins is much lower than that of ethylene and gradually decreases with the increase of the number of carbon chains of α-olefins, in the copolymerization process of ethylene and α-olefins, in order to increase the insertion rate of α-olefins in POE, it is often necessary to control the molar fraction of α-olefins in the monomer mixture at the time of feeding to be much higher than the insertion rate of α-olefins in POE. For example, in patent CN1029850C, when a copolymer of ethylene and 1-octene with a 1-octene insertion rate of about 6 mol% is obtained, the molar fraction of 1-octene in the monomer mixture is about 40 mol% during the feeding; in patent US7807762B2, when a copolymer of ethylene and 1-octene with a 1-octene insertion rate of about 6 mol% is obtained, the molar fraction of 1-octene in the monomer mixture is about 55 mol% during the feeding; in patent CN112552433B, during the feeding, the molar fraction of 1-octene in the monomer mixture is increased to about 80 mol%, and only a copolymer with an insertion rate of 3.5 mol% can be obtained, and at this time, the molar fraction of 1-octene in the monomer mixture has exceeded 20 times the insertion rate of 1-octene in the copolymer.

[0004] In summary, in the process of preparing POE by the prior art, the molar fraction of α-olefin in the monomer mixture when feeding is more than 5 times the insertion rate of α-olefin in the target copolymer, which means that at least 80% of α-olefin does not participate in the reaction, which leads to a large waste of raw materials. At the same time, the recovery and purification of α-olefin in the system requires cumbersome operating steps, which also greatly increases the cost. Summary of the invention

[0005] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for preparing a copolymer of ethylene and α-olefin.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing an ethylene and alpha-olefin copolymer comprises the following steps: dissolving two monomers, ethylene and alpha-olefin, in an inert organic solvent (including toluene, xylene, n-hexane, n-heptane, and methylcyclohexane) under the protection of nitrogen or an inert gas, then using a main catalyst and a co-catalyst for catalysis (the catalytic process is mainly completed by using the co-catalyst to activate the main catalyst to obtain a polymerization active center), and then undergoing coordination copolymerization and post-treatment (i.e., adding an acidified alcohol solution to terminate the polymerization, filtering and washing the polymer, and vacuum drying; in the acidified alcohol solution, the acid refers to hydrochloric acid, and the alcohol refers to methanol, ethanol, and isopropanol, and the volume fraction of the acid in the alcohol solution is 5-20%; washing is performed using methanol, ethanol, isopropanol, deionized water, and acetone, and the number of washings is 1-10; the vacuum degree of vacuum drying is 0.01-0.1 atm, the temperature is 40-80° C., and the time is 12-24 hours), to obtain an ethylene and alpha-olefin copolymer;

[0008] Among them, the main catalyst is a fluorene ring with η 3 Bonding mode coordinated Group IVB metal catalysts;

[0009] The co-catalyst is an aluminum-containing compound or a boron-containing compound;

[0010] The molar fraction of α-olefin in the monomer mixture during feeding is 1.2 to 2.0 times the insertion rate of α-olefin in the copolymer of ethylene and α-olefin, the insertion rate of α-olefin in the copolymer of ethylene and α-olefin is 3 to 20 mol%, and the number average molecular weight of the copolymer of ethylene and α-olefin is 20 to 1000 kg / mol; the reaction equation is as follows:

[0011]

[0012] In the process of preparing POE in the prior art, the molar fraction of α-olefin in the monomer mixture when feeding is more than 5 times the insertion rate of α-olefin in the target copolymer. In the present invention, the molar fraction of α-olefin in the monomer mixture when feeding is 1.2 to 2.0 times the insertion rate of α-olefin in the copolymer of ethylene and α-olefin. By comparison, it can be seen that the present invention can make better use of α-olefin compared with the prior art because: 1) the main catalyst selected by the present invention is a fluorene ring with η 3The invention discloses a bonding mode coordinated IVB group metal catalyst, which has a wider coordination space and has less hindering effect on the coordination and insertion of α-olefin monomers, thereby making it easy for α-olefins in the polymerization system to be inserted into the growing polymer chain, that is, improving the reactivity ratio of α-olefin monomers; 2) The co-catalyst selected in the present invention is an aluminum-containing compound or a boron-containing compound, and the different substituents in its structure interact with the substituents on the catalyst ligands to form relatively loose ion pairs with the central metal, and the loose ion pairs are also beneficial to the coordination and insertion of α-olefin monomers. Therefore, it is finally possible to obtain a copolymer with a higher α-olefin insertion rate under the condition of a lower feed ratio of α-olefin to ethylene, that is, to achieve the purpose of more fully utilizing α-olefins.

[0013] As the preferred technical solution:

[0014] A method for preparing a copolymer of ethylene and α-olefin as described above, wherein the α-olefin is one or more of 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene and 1-eicosene.

[0015] In the method for preparing a copolymer of ethylene and α-olefin as described above, the central metal of the main catalyst is titanium (Ti), zirconium (Zr) or hafnium (Hf) metal.

[0016] In the above-mentioned method for preparing a copolymer of ethylene and α-olefin, the structure of the main catalyst is shown in Formula C, which is as follows:

[0017]

[0018] In the formula, M is titanium, zirconium or hafnium metal; Z is a chlorine atom (Cl) or a methyl group (Me); X is an alkyl group or an aryl group; Y is a silicon atom (Si) or a carbon atom (C); R1 to R9 are each independently selected from hydrogen, halogen, nitro, alkyl, alkoxy, silane, halogenated alkyl, aryl and halogenated aryl, and R x , R x+1 Bonded or non-bonded, x=1,2,...,7.

[0019] In the prior art (such as patent CN1029850C), the main catalyst structure used to prepare ethylene and α-olefin copolymers is shown in formula O, which is as follows:

[0020]

[0021] By comparison, it can be seen that the main difference between Formula O and Formula C in structure is the difference in the cyclopentadiene ring, that is, the lower half of the structure of Formula O is a substituted cyclopentadiene group, and the lower half of the structure of Formula C is a substituted fluorene group. This structural difference will lead to changes in the electronic effect and steric effect of the central metal M, thereby affecting the catalytic performance of the main and co-catalysts and the structure of the polymerization product.

[0022] First, in terms of steric effect, it is mainly due to the different coordination modes between the metal M and the cyclopentadiene group: the metal M in formula O and the substituted cyclopentadiene group are η 5 The metal M in formula C can form η with the substituted fluorene group. 3 The structure of formula C can provide a wider coordination space for the central metal. When ethylene or α-olefins coordinate and insert with the metal, the monomers are less hindered, thus having a higher catalytic activity. At the same time, for α-olefins with longer side chains, the volume occupied by their side chains is also larger, and the wider coordination space of the metal in formula C can increase the competitive polymerization rate of α-olefins during copolymerization with ethylene, and ultimately increase the insertion rate of α-olefins in the copolymer.

[0023] Secondly, in terms of electronic effect, the substituents R1 to R9 in formula C of the present invention are groups with strong electron donating properties. For example, the substituents R1 to R8 on the fluorene ring are electron donating groups such as tert-butyl and methoxy, and the substituent R9 is an electron donating group such as tert-butyl and adamantane. The introduction of such electron donating groups will weaken the Lewis acidity of the central metal M, which will bring two advantages: 1) the central metal M with weaker Lewis acidity will generate a looser ion pair with anions after activation with a co-catalyst, which is beneficial to the coordination and insertion of α-olefin monomers; 2) the central metal M with weaker Lewis acidity will obtain a four-membered ring transition state structure with weaker stability when coordinated with the olefin double bond, thereby reducing the activation energy of the olefin monomer inserted into the polymer growth chain; the above two advantages will be beneficial to improving the catalytic activity and the reactivity ratio during the copolymerization of α-olefin and ethylene, and ultimately can improve the insertion rate of α-olefin in the copolymer.

[0024] In the method for preparing a copolymer of ethylene and α-olefin as described above, formula C is any one of formulas C1 to C35, and formulas C1 to C35 are as follows:

[0025]

[0026]

[0027] In the above-mentioned method for preparing a copolymer of ethylene and α-olefin, the structure of the co-catalyst is shown in formulas D1 to D9, and formulas D1 to D9 are as follows:

[0028]

[0029] In the method for preparing a copolymer of ethylene and α-olefin as described above, when the co-catalyst is an aluminum-containing compound, it is also subjected to a decompression treatment before feeding to remove small molecular compounds such as alkyl aluminum in the co-catalyst, thereby reducing the chain transfer reaction in the polymerization process, so that the obtained product has a higher molecular weight, and the molar ratio of the co-catalyst to the main catalyst is 10 to 1000:1; when the co-catalyst is a boron-containing compound, an impurity remover is also added to the polymerization system to remove residual moisture, oxygen and other impurities in the polymerization system, the impurity remover is triisobutylaluminum and / or trimethylaluminum, the molar ratio of the co-catalyst to the main catalyst is 1:1, and the molar ratio of the impurity remover to the main catalyst is 10 to 100:1.

[0030] The preparation method of the ethylene and α-olefin copolymer as described above has the following specific process: first, under the protection of nitrogen or inert gas, the two monomers of ethylene and α-olefin are dissolved in an inert organic solvent, then a co-catalyst solution is added to the polymerization system and the system is kept warm, and finally a main catalyst solution is added to the polymerization system to initiate a coordination copolymerization reaction, and after reaching the polymerization time, post-treatment is performed to obtain the ethylene and α-olefin copolymer.

[0031] In the method for preparing a copolymer of ethylene and α-olefin as described above, dissolving the two monomers of ethylene and α-olefin in an inert organic solvent means that after dissolving the α-olefin in the inert organic solvent, ethylene gas is introduced until the ethylene is dissolved in the inert organic solvent and reaches saturation.

[0032] In the method for preparing a copolymer of ethylene and α-olefin as described above, the pressure of the ethylene gas is 1 to 50 atm.

[0033] In the method for preparing a copolymer of ethylene and α-olefin as described above, the molar ratio of α-olefin to main catalyst is 20000:1 to 200000:1, the polymerization temperature ranges from 0 to 230°C, the polymerization time is 1 to 300 minutes, and the insulation time is 10 to 30 minutes.

[0034] Beneficial Effects

[0035] (1) Compared with the prior art, the present invention can make better use of α-olefins. The molar fraction of α-olefin in the monomer mixture during feeding is 1.2 to 2.0 times the insertion rate of α-olefin in the ethylene and α-olefin copolymer. The ethylene and α-olefin copolymer finally obtained has excellent comprehensive properties and controllable chain structure parameters.

[0036] (2) The catalyst system selected in the present invention has high catalytic activity (10 7 ~10 9 g·mol -1 h -1The number average molecular weight of the ethylene and α-olefin copolymer can reach a level higher than that of the prior art. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0038] The following are the test methods for each performance in the embodiments:

[0039] Catalytic activity: Weigh the total weight of the dried product and calculate it based on the amount of catalyst used and polymerization time, where the unit of weight is gram (g), the unit of catalyst used is mole (mol), and the unit of time is hour (h). The unit of the calculated activity is gram per mole per hour (g·mol -1 h -1 ).

[0040] α-olefin insertion rate in ethylene and α-olefin copolymers: The copolymer was dissolved in 1,1,2,2-deuterated tetrachloroethane (1,1,2,2-C2D2Cl4) at 90°C and tested using a 600MHz nuclear magnetic resonance spectrometer. According to the quantitative hydrogen spectrum ( 1 HNMR) or carbon spectroscopy ( 13 The ratio of the integrated area of ​​the characteristic peaks on C NMR can be used to calculate the insertion rate of α-olefin in the copolymer of ethylene and α-olefin.

[0041] Number average molecular weight: Dissolve the polymer in 1,2,4-trichlorobenzene at 150°C to prepare a solution with a concentration of 1 mg / mL. Filter the polymer solution and inject it into the injection port of a high-temperature gel permeation chromatograph (GPC). Set the flow rate of 1,2,4-trichlorobenzene eluent to 1.0 mL / min for testing and read the number average molecular weight M on the instrument. n data.

[0042] Example 1

[0043] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0044] (1) Preparation of raw materials;

[0045] The α-olefin is 1-pentene;

[0046] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0047] A co-catalyst solution with a concentration of 1.5 mmol / mL: the co-catalyst is an aluminum-containing compound that has been subjected to a decompression treatment, and the structural formula of the aluminum-containing compound is: The solvent is toluene;

[0048] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is methanol, and the volume fraction of the acid in the alcohol is 5%;

[0049] Inert organic solvent: toluene;

[0050] (2) Under nitrogen protection, an α-olefin is dissolved in an inert organic solvent at 90° C., and ethylene gas at a pressure of 1 atm is introduced until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 3.6 mol% of the mixture of the α-olefin and ethylene;

[0051] (3) adding the co-catalyst solution to the polymerization system and keeping the temperature at 90°C for 10 minutes;

[0052] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 45 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of α-olefin to main catalyst is 20000:1; and the molar ratio of co-catalyst to main catalyst is 300:1;

[0053] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 3.5×10 7 g·mol -1 h -1 .

[0054] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 3.0 mol%. The molar fraction of α-olefin in the monomer mixture during feeding is 1.2 times the α-olefin insertion rate in the ethylene and α-olefin copolymer. The number average molecular weight of the ethylene and α-olefin copolymer is 330 kg / mol.

[0055] Comparative Example 1

[0056] A method for preparing a copolymer of ethylene and α-olefin is basically the same as that of Example 1, except that: the structural formula of the main catalyst in step (1) is In step (2), the molar fraction of α-olefin in the inert organic solvent to the mixture of α-olefin and ethylene is 17.64 mol%.

[0057] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 2.8 mol%. The molar fraction of α-olefin in the monomer mixture during feeding is 6.3 times the α-olefin insertion rate in the ethylene and α-olefin copolymer. The number average molecular weight of the ethylene and α-olefin copolymer is 185 kg / mol.

[0058] Comparison of Comparative Example 1 and Example 1 shows that since the main catalyst used in Comparative Example 1 is tetramethylcyclopentadiene with n 5 The bonding mode coordinated titanium metal catalyst will result in a significantly higher molar fraction of α-olefin in the monomer mixture than the α-olefin insertion rate in the ethylene and α-olefin copolymer. This is because the central metal of this type of catalyst forms an η 5 The bonding mode results in a smaller coordination space around the central metal, which is not conducive to the insertion of α-olefin monomers. Therefore, in order to achieve the same level of α-olefin insertion rate, it is necessary to maintain a higher molar fraction of α-olefin in the monomer mixture during feeding, which will increase the preparation cost.

[0059] Comparative Example 2

[0060] A method for preparing a copolymer of ethylene and α-olefin is basically the same as that of Example 1, except that: the structural formula of the main catalyst in step (1) is In step (2), the molar fraction of α-olefin in the inert organic solvent to the mixture of α-olefin and ethylene is 34.65 mol%.

[0061] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 3.3 mol%. The molar fraction of α-olefin in the monomer mixture during feeding is 10.5 times the α-olefin insertion rate in the ethylene and α-olefin copolymer. The number average molecular weight of the ethylene / α-olefin copolymer is 279 kg / mol.

[0062] Comparison of Comparative Example 2 and Example 1 shows that since the main catalyst used in Comparative Example 2 is an indene ring with η 5 The zirconium metal catalyst with bonding mode coordination will result in a significantly higher molar fraction of α-olefin in the monomer mixture when feeding than the α-olefin insertion rate in the copolymer of ethylene and α-olefin. This is because the central metal of this type of catalyst forms η with the cyclopentadiene group. 5 The bonding mode results in a smaller coordination space around the central metal, which is not conducive to the insertion of α-olefin monomers. Therefore, in order to achieve the same level of α-olefin insertion rate, it is necessary to maintain a higher molar fraction of α-olefin in the monomer mixture when feeding. Moreover, when the molar fraction of ethylene in the system decreases, the overall activity of the catalytic system will also be significantly reduced.

[0063] Example 2

[0064] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0065] (1) Preparation of raw materials;

[0066] The α-olefin is 1-hexene;

[0067] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0068] A co-catalyst solution with a concentration of 1.5 mmol / mL: the co-catalyst is an aluminum-containing compound that has been subjected to a decompression treatment, and the structural formula of the aluminum-containing compound is: The solvent is toluene;

[0069] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is ethanol, and the volume fraction of the acid in the alcohol is 10%;

[0070] Inert organic solvent: xylene;

[0071] (2) under the protection of an inert gas, after dissolving an α-olefin in an inert organic solvent at 230° C., introducing ethylene gas at a pressure of 5 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 21.53 mol% of the mixture of the α-olefin and ethylene;

[0072] (3) adding the co-catalyst solution to the polymerization system and keeping the temperature at 230° C. for 30 min;

[0073] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 1 minute, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 38000:1; and the molar ratio of the co-catalyst to the main catalyst is 1000:1;

[0074] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 6.8×10 7 g·mol -1 h -1 .

[0075] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 12.3 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.75 times the α-olefin insertion rate in the ethylene and α-olefin copolymer. The number average molecular weight of the ethylene and α-olefin copolymer is 80 kg / mol.

[0076] Example 3

[0077] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0078] (1) Preparation of raw materials;

[0079] The α-olefin is 1-octene;

[0080] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0081] A co-catalyst solution with a concentration of 1.0 mmol / mL: the co-catalyst is an aluminum-containing compound that has been subjected to a decompression treatment, and the structural formula of the aluminum-containing compound is: The solvent is toluene;

[0082] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is isopropanol, and the volume fraction of the acid in the alcohol is 15%;

[0083] Inert organic solvent: n-hexane;

[0084] (2) under nitrogen protection, after dissolving an α-olefin in an inert organic solvent at 0° C., introducing ethylene gas at a pressure of 15 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 10.63 mol% of the mixture of the α-olefin and ethylene;

[0085] (3) adding the co-catalyst solution to the polymerization system and keeping it at 0°C for 25 minutes;

[0086] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 300 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 72000:1; and the molar ratio of the co-catalyst to the main catalyst is 800:1;

[0087] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 8.2×10 7 g·mol -1 h -1 .

[0088] The α-olefin insertion rate of the finally prepared ethylene and α-olefin copolymer is 7.7 mol%. The molar fraction of α-olefin in the monomer mixture during feeding is 1.38 times the α-olefin insertion rate in the ethylene and α-olefin copolymer, and the number average molecular weight of the ethylene and α-olefin copolymer is 680 kg / mol.

[0089] Example 4

[0090] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0091] (1) Preparation of raw materials;

[0092] The α-olefin is 1-decene;

[0093] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0094] A co-catalyst solution with a concentration of 1.0 mmol / mL: the co-catalyst is an aluminum-containing compound that has been subjected to a decompression treatment, and the structural formula of the aluminum-containing compound is: The solvent is toluene;

[0095] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is methanol, and the volume fraction of the acid in the alcohol is 10%;

[0096] Inert organic solvent: n-heptane;

[0097] (2) under the protection of an inert gas, after dissolving an α-olefin in an inert organic solvent at 30° C., introducing ethylene gas at a pressure of 25 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 11.81 mol % of the mixture of the α-olefin and ethylene;

[0098] (3) adding the co-catalyst solution to the polymerization system and keeping it at 30°C for 15 minutes;

[0099] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 120 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 105000:1; and the molar ratio of the co-catalyst to the main catalyst is 50:1;

[0100] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 2.8×10 8 g·mol -1 h -1 .

[0101] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 8.2 mol%. The molar fraction of α-olefin in the monomer mixture during feeding is 1.44 times the α-olefin insertion rate in the ethylene and α-olefin copolymer, and the number average molecular weight of the ethylene and α-olefin copolymer is 96 kg / mol.

[0102] Example 5

[0103] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0104] (1) Preparation of raw materials;

[0105] The α-olefin is 1-dodecene;

[0106] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0107] A co-catalyst solution with a concentration of 1.5 mmol / mL: the co-catalyst is an aluminum-containing compound that has been subjected to a decompression treatment, and the structural formula of the aluminum-containing compound is: The solvent is toluene;

[0108] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is ethanol, and the volume fraction of the acid in the alcohol is 5%;

[0109] Inert organic solvent: methylcyclohexane;

[0110] (2) under nitrogen protection, after dissolving an α-olefin in an inert organic solvent at 60° C., introducing ethylene gas at a pressure of 50 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 17.44 mol% of the mixture of the α-olefin and ethylene;

[0111] (3) adding the co-catalyst solution to the polymerization system and keeping the temperature at 60°C for 20 minutes;

[0112] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 180 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 150000:1; and the molar ratio of the co-catalyst to the main catalyst is 100:1;

[0113] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 4.8×10 7 g·mol -1 h -1 .

[0114] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 10.9 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.60 times the α-olefin insertion rate in the ethylene and α-olefin copolymer. The number average molecular weight of the ethylene and α-olefin copolymer is 1000 kg / mol.

[0115] Example 6

[0116] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0117] (1) Preparation of raw materials;

[0118] The α-olefin is 1-tetradecene;

[0119] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0120] A co-catalyst solution with a concentration of 1.0 mmol / mL: the co-catalyst is an aluminum-containing compound that has been subjected to a decompression treatment, and the structural formula of the aluminum-containing compound is: The solvent is toluene;

[0121] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is ethanol, and the volume fraction of the acid in the alcohol is 20%;

[0122] Inert organic solvent: toluene;

[0123] (2) under the protection of an inert gas, after dissolving an α-olefin in an inert organic solvent at 120° C., introducing ethylene gas at a pressure of 35 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 28.37 mol% of the mixture of the α-olefin and ethylene;

[0124] (3) adding the co-catalyst solution to the polymerization system and keeping the temperature at 120° C. for 15 min;

[0125] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 30 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 200000:1; and the molar ratio of the co-catalyst to the main catalyst is 200:1;

[0126] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 5.7×10 7 g·mol -1 h -1 .

[0127] The α-olefin insertion rate of the finally prepared ethylene and α-olefin copolymer is 15.5 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.83 times the α-olefin insertion rate of the ethylene and α-olefin copolymer. The number average molecular weight of the ethylene and α-olefin copolymer is 770 kg / mol.

[0128] Example 7

[0129] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0130] (1) Preparation of raw materials;

[0131] The α-olefin is 1-eicosene;

[0132] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0133] A co-catalyst solution with a concentration of 1.5 mmol / mL: the co-catalyst is an aluminum-containing compound that has been subjected to a decompression treatment, and the structural formula of the aluminum-containing compound is: The solvent is toluene;

[0134] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is isopropanol, and the volume fraction of the acid in the alcohol is 5%;

[0135] Inert organic solvent: xylene;

[0136] (2) under nitrogen protection, after dissolving an α-olefin in an inert organic solvent at 150° C., introducing ethylene gas at a pressure of 40 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 40.0 mol% of the mixture of the α-olefin and ethylene;

[0137] (3) adding the co-catalyst solution to the polymerization system and keeping the temperature at 150° C. for 30 min;

[0138] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 90 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 185000:1; and the molar ratio of the co-catalyst to the main catalyst is 10:1;

[0139] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 7.4×10 7 g·mol -1 h -1 .

[0140] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 20.0 mol%. The molar fraction of α-olefin in the monomer mixture during feeding is 2.0 times the α-olefin insertion rate in the ethylene and α-olefin copolymer. The number average molecular weight of the ethylene and α-olefin copolymer is 505 kg / mol.

[0141] Example 8

[0142] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0143] (1) Preparation of raw materials;

[0144] The α-olefin is 1-hexene;

[0145] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0146] A co-catalyst solution with a concentration of 10.0 μmol / mL: the co-catalyst is a boron-containing compound with the structural formula: The solvent is toluene;

[0147] Impurity remover solution: a toluene solution of triisobutylaluminum with a concentration of 20 μmol / mL, wherein the solute is triisobutylaluminum and the solvent is toluene;

[0148] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is methanol, and the volume fraction of the acid in the alcohol is 5%;

[0149] Inert organic solvent: toluene;

[0150] (2) under nitrogen protection, dissolving an α-olefin in an inert organic solvent at 60° C., introducing ethylene gas at a pressure of 10 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 10.43 mol% of the mixture of the α-olefin and the ethylene gas;

[0151] (3) adding a co-catalyst solution and an impurity remover solution to the polymerization system and keeping the temperature at 60° C. for 10 min;

[0152] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 45 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying the product to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 85800:1; the molar ratio of the co-catalyst to the main catalyst is 1:1; and the molar ratio of the impurity remover to the main catalyst is 10:1;

[0153] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 7.3×10 8 g·mol -1 h -1 .

[0154] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 7.9 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.32 times the α-olefin insertion rate in the ethylene and α-olefin copolymer; the number average molecular weight of the ethylene and α-olefin copolymer is 230 kg / mol.

[0155] Example 9

[0156] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0157] (1) Preparation of raw materials;

[0158] The α-olefin is 1-heptene;

[0159] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0160] A co-catalyst solution with a concentration of 10.0 μmol / mL: the co-catalyst is a boron-containing compound with the structural formula: The solvent is toluene;

[0161] Impurity remover: a toluene solution of trimethylaluminum with a concentration of 20 μmol / mL, the solute is trimethylaluminum, and the solvent is toluene;

[0162] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is ethanol, and the volume fraction of the acid in the alcohol is 10%;

[0163] Inert organic solvent: xylene;

[0164] (2) under the protection of an inert gas, after dissolving an α-olefin in an inert organic solvent at 80° C., introducing ethylene gas at a pressure of 20 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 20.13 mol% of the mixture of the α-olefin and the ethylene gas;

[0165] (3) adding a co-catalyst solution and an impurity remover to the polymerization system and keeping the system at 80° C. for 30 min;

[0166] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 30 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 58500:1; the molar ratio of the co-catalyst to the main catalyst is 1:1; and the molar ratio of the impurity remover to the main catalyst is 20:1;

[0167] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 5.5×108 g·mol -1 h -1 .

[0168] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 11.5 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.75 times the α-olefin insertion rate in the ethylene and α-olefin copolymer; the number average molecular weight of the ethylene and α-olefin copolymer is 20 kg / mol.

[0169] Example 10

[0170] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0171] (1) Preparation of raw materials;

[0172] The α-olefin is 1-octene;

[0173] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0174] A co-catalyst solution with a concentration of 10.0 μmol / mL: the co-catalyst is a boron-containing compound with the structural formula: The solvent is toluene;

[0175] Impurity remover: a toluene solution of triisobutylaluminum with a concentration of 20 μmol / mL, wherein the solute is triisobutylaluminum and the solvent is toluene;

[0176] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is isopropanol, and the volume fraction of the acid in the alcohol is 15%;

[0177] Inert organic solvent: n-hexane;

[0178] (2) under nitrogen protection, after dissolving an α-olefin in an inert organic solvent at 90° C., introducing ethylene gas at a pressure of 30 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 12.85 mol% of the mixture of the α-olefin and the ethylene gas;

[0179] (3) adding a co-catalyst solution and an impurity remover to the polymerization system and keeping the system at 90° C. for 25 min;

[0180] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 60 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying the product to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 120000:1; the molar ratio of the co-catalyst to the main catalyst is 1:1; and the molar ratio of the impurity remover to the main catalyst is 40:1;

[0181] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 9.8×10 7 g·mol -1 h -1 .

[0182] The α-olefin insertion rate of the finally prepared ethylene and α-olefin copolymer is 8.8 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.46 times the α-olefin insertion rate of the ethylene and α-olefin copolymer; the number average molecular weight of the ethylene and α-olefin copolymer is 77 kg / mol.

[0183] Embodiment 11

[0184] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0185] (1) Preparation of raw materials;

[0186] The α-olefin is 1-decene;

[0187] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0188] A co-catalyst solution with a concentration of 10.0 μmol / mL: the co-catalyst is a boron-containing compound with the structural formula: The solvent is toluene;

[0189] Impurity remover: a toluene solution of trimethylaluminum with a concentration of 20 μmol / mL, the solute is trimethylaluminum, and the solvent is toluene;

[0190] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is methanol, and the volume fraction of the acid in the alcohol is 10%;

[0191] Inert organic solvent: n-heptane;

[0192] (2) under the protection of an inert gas, after dissolving an α-olefin in an inert organic solvent at 120° C., introducing ethylene gas at a pressure of 40 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 26.0 mol% of the mixture of the α-olefin and the ethylene gas;

[0193] (3) adding a co-catalyst solution and an impurity remover to the polymerization system and keeping the system at 120° C. for 15 min;

[0194] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 75 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying the product to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 175000:1; the molar ratio of the co-catalyst to the main catalyst is 1:1; and the molar ratio of the impurity remover to the main catalyst is 60:1;

[0195] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 1.5×10 9 g·mol -1 h -1 .

[0196] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 14.2 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.83 times the α-olefin insertion rate in the ethylene and α-olefin copolymer; the number average molecular weight of the ethylene and α-olefin copolymer is 355 kg / mol.

[0197] Example 12

[0198] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0199] (1) Preparation of raw materials;

[0200] The α-olefin is 1-dodecene;

[0201] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0202] A co-catalyst solution with a concentration of 10.0 μmol / mL: the co-catalyst is a boron-containing compound with the structural formula: The solvent is toluene;

[0203] Impurity remover: a toluene solution of triisobutylaluminum with a concentration of 20 μmol / mL, wherein the solute is triisobutylaluminum and the solvent is toluene;

[0204] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is ethanol, and the volume fraction of the acid in the alcohol is 5%;

[0205] Inert organic solvent: methylcyclohexane;

[0206] (2) under nitrogen protection, after dissolving an α-olefin in an inert organic solvent at 130° C., introducing ethylene gas at a pressure of 50 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 32.45 mol% of the mixture of the α-olefin and the ethylene gas;

[0207] (3) adding a co-catalyst solution and an impurity remover to the polymerization system and keeping the temperature at 130° C. for 20 min;

[0208] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 150 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying the product to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 160000:1; the molar ratio of the co-catalyst to the main catalyst is 1:1; and the molar ratio of the impurity remover to the main catalyst is 80:1;

[0209] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 2.1×10 8 g·mol -1 h -1 .

[0210] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 16.9 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.92 times the α-olefin insertion rate in the ethylene and α-olefin copolymer; the number average molecular weight of the ethylene and α-olefin copolymer is 810 kg / mol.

[0211] Embodiment 13

[0212] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0213] (1) Preparation of raw materials;

[0214] The α-olefin is 1-pentadecene;

[0215] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0216] A co-catalyst solution with a concentration of 10.0 μmol / mL: the co-catalyst is a boron-containing compound with the structural formula: The solvent is toluene;

[0217] Impurity remover: a toluene solution of trimethylaluminum with a concentration of 20 μmol / mL, the solute is trimethylaluminum, and the solvent is toluene;

[0218] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is ethanol, and the volume fraction of the acid in the alcohol is 20%;

[0219] Inert organic solvent: toluene;

[0220] (2) under the protection of an inert gas, after dissolving an α-olefin in an inert organic solvent at 150° C., introducing ethylene gas at a pressure of 35 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 17.43 mol% of the mixture of the α-olefin and the ethylene gas;

[0221] (3) adding a co-catalyst solution and an impurity remover to the polymerization system and keeping the system at 150° C. for 15 min;

[0222] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 15 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 100000:1; the molar ratio of the co-catalyst to the main catalyst is 1:1; and the molar ratio of the impurity remover to the main catalyst is 100:1;

[0223] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 9.4×10 8 g·mol -1 h -1 .

[0224] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 10.5 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.66 times the α-olefin insertion rate in the ethylene and α-olefin copolymer; the number average molecular weight of the ethylene and α-olefin copolymer is 47 kg / mol.

[0225] Embodiment 14

[0226] A method for preparing a copolymer of ethylene and α-olefin, the specific steps are as follows:

[0227] (1) Preparation of raw materials;

[0228] The α-olefin is 1-octadecene;

[0229] The main catalyst solution with a concentration of 1.0 μmol / mL: The structural formula of the main catalyst is: The solvent is toluene;

[0230] A co-catalyst solution with a concentration of 10.0 μmol / mL: the co-catalyst is a boron-containing compound with the structural formula: The solvent is toluene;

[0231] Impurity remover: a toluene solution of triisobutylaluminum with a concentration of 20 μmol / mL, wherein the solute is triisobutylaluminum and the solvent is toluene;

[0232] Acidified alcohol solution: the acid is hydrochloric acid, the alcohol is isopropanol, and the volume fraction of the acid in the alcohol is 5%;

[0233] Inert organic solvent: xylene;

[0234] (2) under nitrogen protection, after dissolving an α-olefin in an inert organic solvent at 40° C., introducing ethylene gas at a pressure of 25 atm until the ethylene is dissolved in the inert organic solvent and reaches saturation; wherein the molar fraction of the α-olefin in the inert organic solvent accounts for 15.0 mol% of the mixture of the α-olefin and the ethylene gas;

[0235] (3) adding a co-catalyst solution and an impurity remover to the polymerization system and keeping the system at 40° C. for 30 min;

[0236] (4) adding a main catalyst solution to the polymerization system to initiate a coordination copolymerization reaction, and after reacting for 240 minutes, adding an acidified alcohol solution to terminate the polymerization, filtering and washing the product, and vacuum drying to obtain an ethylene and α-olefin copolymer; wherein the molar ratio of the α-olefin to the main catalyst is 50000:1; the molar ratio of the co-catalyst to the main catalyst is 1:1; and the molar ratio of the impurity remover to the main catalyst is 50:1;

[0237] During the polymerization process, the catalytic activity of the catalyst system (main catalyst and co-catalyst) was 5.7×10 8 g·mol -1 h -1 .

[0238] The α-olefin insertion rate in the final ethylene and α-olefin copolymer is 9.8 mol%, and the molar fraction of α-olefin in the monomer mixture during feeding is 1.53 times the α-olefin insertion rate in the ethylene and α-olefin copolymer; the number average molecular weight of the ethylene and α-olefin copolymer is 900 kg / mol.

Claims

1. A method for preparing a copolymer of ethylene and α-olefin, characterized in that: Under the protection of nitrogen or inert gas, two monomers, ethylene and α-olefin, are dissolved in an inert organic solvent, and then catalyzed by a main catalyst and a co-catalyst, and subjected to coordination copolymerization reaction and post-treatment to obtain a copolymer of ethylene and α-olefin; Wherein, the structure of the main catalyst is shown in Formula C, Formula C is any one of Formulas C2, C3, C7, C8, C12, C13, C16, C19, C22, C23, and C25, and Formulas C2, C3, C7, C8, C12, C13, C16, C19, C22, C23, and C25 are as follows: The co-catalyst is an aluminum-containing compound or a boron-containing compound; The molar fraction of α-olefin in the monomer mixture during feeding is 1.2 to 2.0 times the insertion rate of α-olefin in the copolymer of ethylene and α-olefin, the insertion rate of α-olefin in the copolymer of ethylene and α-olefin is 3 to 20 mol%, and the number average molecular weight of the copolymer of ethylene and α-olefin is 20 to 1000 kg / mol.

2. The method for preparing a copolymer of ethylene and α-olefin according to claim 1, characterized in that: The α-olefin is one or more of 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene and 1-eicosene.

3. The method for preparing a copolymer of ethylene and α-olefin according to claim 1, characterized in that: The structures of the co-catalysts are shown in formulas D1 to D9, which are as follows:

4. The method for preparing a copolymer of ethylene and α-olefin according to claim 1, characterized in that: The co-catalyst is an aluminum-containing compound, which is subjected to a decompression treatment before feeding, and the molar ratio of the co-catalyst to the main catalyst is 10 to 1000:1; or, the co-catalyst is a boron-containing compound, and an impurity remover is added to the polymerization system, the impurity remover is triisobutylaluminum and / or trimethylaluminum, the molar ratio of the co-catalyst to the main catalyst is 1:1, and the molar ratio of the impurity remover to the main catalyst is 10 to 100:

1.

5. The method for preparing a copolymer of ethylene and α-olefin according to claim 1, characterized in that: The specific process is: first, under the protection of nitrogen or inert gas, the two monomers of ethylene and α-olefin are dissolved in an inert organic solvent, then the co-catalyst solution is added to the polymerization system and kept warm, and finally the main catalyst solution is added to the polymerization system to initiate the coordination copolymerization reaction, and after reaching the polymerization time, post-treatment is carried out to obtain ethylene and α-olefin copolymers.

6. The method for preparing a copolymer of ethylene and α-olefin according to claim 5, characterized in that: Dissolving two monomers, ethylene and α-olefin, in an inert organic solvent means that after dissolving the α-olefin in the inert organic solvent, ethylene gas is introduced until the ethylene is dissolved in the inert organic solvent and reaches saturation.

7. The method for preparing a copolymer of ethylene and α-olefin according to claim 5, characterized in that: The molar ratio of alpha-olefin to main catalyst is 20000:1-200000:1, the polymerization temperature ranges from 0 to 230°C, the polymerization time is 1 to 300 minutes, and the heat preservation time is 10 to 30 minutes.

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