Random copolymer of ethylene and alpha-olefin and preparation method thereof

Abstract

The invention provides a random copolymer of ethylene and alpha-olefin and a preparation method thereof. The preparation method comprises the following steps: reacting ethylene and alpha-olefin at 80-100 DEG C under the action of a metallocene compound and a cocatalyst to obtain the random copolymer of ethylene and alpha-olefin, the cocatalyst comprises organic aluminum; the metallocene compound has a structure as shown in a formula I or a formula II; and the molar ratio of aluminum in the cocatalyst to M in the metallocene compound is 800-1500. The preparation method can be used for preparing the random copolymer of ethylene and alpha-olefin.

Description

Technical Field

[0001] This invention belongs to the field of metallocene catalyst technology, specifically relating to a random copolymer of ethylene and α-olefin and its preparation method. Background Technology

[0002] The most significant advancement in the polyolefin industry has been the application of metallocene catalysts in catalytic olefin polymerization, leading to a revolutionary change in the entire industry. Compared to the traditional Ziegler-Natta catalytic system, metallocene catalysts possess advantages such as extremely high catalytic activity, a single active center, excellent catalytic copolymerization ability, and controllable polymer structure. Exxon uses metallocene catalysts for the industrial production of linear low-density polyethylene (mLLDPE), and Dow Chemical's defined geometry catalyst technology (CGCT) is also applied to the industrial production of polyolefin products (POE, mEPDM).

[0003] CN102190687A discloses a configuration-restricted carbon-bridged monometallocene compound, its preparation and application; the general structural formula is shown below:

[0004]

[0005] Wherein: R = H, allyl or tert-butyl containing 1-10 carbon atoms; R1, R2 = H, alkyl, allyl, aromatic or silyl containing 1-10 carbon atoms; M = Ti or Zr; Cp is cadmium, substituted cadmium, indene or substituted indene; suitable for catalyzing the copolymerization of ethylene / hexene-1 and ethylene / octene-1, with a polymerization activity of 2.76 × 10⁻⁶ at a reaction temperature of 70℃, a reaction time of 0.5 h, an aluminum / zirconium ratio of 1000, an octene-1 concentration of 0.6 mol / L, and an ethylene pressure of 0.1 MPa. 6 With a PE / mol·cat·h ratio, the polymer contains 19.07% octene-1, exhibiting high catalytic activity during copolymerization and a high insertion rate of long-chain α-olefins. This approach improves catalyst performance by introducing different substituents onto the cyclopentadiene ring.

[0006] The petrochemical industry is committed to improving the performance of natural mineral base oils with synthetic hydrocarbons, and high-grade lubricating oil base oils are developing towards lower viscosity and higher viscosity index. Industrial research on synthetic lubricants mainly focuses on increasing the viscosity of liquids usable over a wide temperature range. Compared to mineral oils, synthetic lubricants have higher viscosity indexes, better lubrication capabilities, thermal stability, oxidation stability, and lower pour points, as well as lower coefficients of friction. Therefore, they offer higher mechanical efficiency than mineral oils under a range of operating conditions and loads. The viscosity-temperature relationship of lubricating oils is considered a key index. When mineral oils are used as single-phase or multiphase lubricants, their viscosity varies greatly with ambient temperature, resulting in a lower viscosity index. High viscosity index lubricants are more ideal, maintaining high viscosity even at high temperatures, providing better lubrication and protection in machinery applications.

[0007] PAOs are synthetic hydrocarbons that can be used as base oils for lubrication. They are derived from α-olefin monomers, typically 1-octene to 1-dodecene, with 1-decene being the most desirable. PAOs exhibit good flow properties at low temperatures, relatively high thermal and oxidative stability, low vapor loss at high temperatures, high viscosity index, good frictional properties, good hydraulic stability, and good wear resistance. PAOs are non-toxic and readily miscible with mineral oils or greases, making them suitable for use as engine oils, compressor oils, hydraulic oils, gear oils, or greases. PAOs contain easily oxidized tertiary hydrogens, which decreases their stability; therefore, the amount of tertiary hydrogens should be minimized to improve the oxidative stability of the synthetic hydrocarbons.

[0008] Metallocene catalysts possess advantages such as high catalytic activity, narrow molecular weight distribution of the resulting polymers, controllable polymer structure, and customizable polymer molecules. Therefore, they have significant advantages in the synthesis of polyalphaolefin (PAO) base oils in the lubricating oil field, yielding PAO base oils with controllable compositional distribution. US8536391B2 proposes a method for synthesizing PAOs from alpha-olefins using supported metallocene catalysts. The metallocene catalytic system used includes a metallocene and a solid oxide chemically treated with electron-withdrawing anions. The resulting polyalphaolefins and PAOs have high viscosity indices and low pour points, with a Kv of 20-1200 cSt at 100°C and a pour point below 20°C. The PAOs are primarily head-to-tail bonds, offering significant application value in lubricating oils and viscosity correction. However, the product distribution is relatively broad, mainly consisting of alpha-olefins containing unsaturated double bonds and partially hydrogenated alpha-olefins. Experiments have shown that the presence of unsaturated double bonds in PAOs affects the stability of lubricating oils.

[0009] CN113046130A and CN113136254A both prepared a narrow-distribution PAO base oil using a two-step method, wherein tBuNCCH3(C6H5)(η 5 -C5H4)ZrCl2、tBuNC(CH3)2(η 5C5H4)ZrCl2 and tBuNSi(CH3)2(η 5 Metallocene catalysts such as C5H4 and ZrCl2 catalyze the oligomerization of C8-C12 α-olefins, ultimately yielding PAO base oils with narrow viscosity distribution and high viscosity index. CN113150826A uses a restricted configuration metallocene catalyst to catalyze the oligomerization of α-olefins with 8-12 carbon atoms, yielding a mixture of α-olefin oligomers, ultimately resulting in a polyalphaolefin base oil with low viscosity and high viscosity index. All of the above utilize homogeneous metallocene catalyst systems with a single active site, leveraging the advantages of high activity, narrow molecular weight distribution of the resulting polymers, controllable polymer structure, and customizable polymer molecules to produce narrowly distributed PAO base oils in a two-step process. However, the preparation process is complex and lengthy. Summary of the Invention

[0010] To address the aforementioned problems, the present invention aims to provide a random copolymer of ethylene and α-olefins and a method for preparing the same. This preparation method can yield a random copolymer of ethylene and α-olefins.

[0011] To achieve the above objectives, the present invention provides a method for preparing a random copolymer of ethylene and α-olefin, comprising the following steps: reacting ethylene and α-olefin at 80-100°C in the presence of a metallocene compound and a co-catalyst to obtain the random copolymer of ethylene and α-olefin; the co-catalyst comprising an organoaluminum compound (e.g., MAO); the metallocene compound having the structure shown in Formula I or Formula II:

[0012]

[0013] In Formula I, M is selected from Zr or Ti, Cp is selected from cadmium, substituted cadmium, indene or substituted indene; R1 is selected from C2-C4 alkylene and its derivatives; R2 is selected from C1-C4 alkyl and its derivatives.

[0014]

[0015] In Formula II, M is selected from Zr or Ti, Cp is selected from cadmium, substituted cadmium, indene or substituted indene; R1 is selected from C2-C4 alkylene and its derivatives; R2 is selected from C1-C4 alkyl and its derivatives; the molar ratio of aluminum in the cocatalyst to M in the metallocene compound is 800-1500 (more preferably 1000).

[0016] According to a specific embodiment of the present invention, preferably, the α-olefin accounts for more than 15% of the total volume of the reactant system, and the reactant system includes a metallocene compound, a solvent, a co-catalyst, and an α-olefin.

[0017] According to a specific embodiment of the present invention, preferably, the ethylene pressure is 0.50-3.0 MPa.

[0018] According to a specific embodiment of the present invention, the method for preparing the above-mentioned random copolymer of ethylene and α-olefin includes the following specific steps:

[0019] A metallocene compound, solvent, co-catalyst, and α-olefin were mixed and reacted with ethylene. After the reaction was complete, a hydrochloric acid-ethanol solution was added to terminate the reaction. The mixture was then washed and dried to obtain a random copolymer of ethylene and α-olefin.

[0020] According to a specific embodiment of the present invention, preferably, in Formula I, R1 is selected from C2-C4 alkylene groups; R2 is selected from C1-C4 alkyl groups.

[0021] According to a specific embodiment of the present invention, preferably, in Formula I, Cp is selected from cyclopentadiene, butylcyclopentadiene, methylcyclopentadiene (e.g., tetramethylcyclopentadiene), and indene.

[0022] According to a specific embodiment of the present invention, preferably, R1 is selected from ethylene, propylene, and butylene; and R2 is selected from methyl, ethyl, propyl, and butyl.

[0023] According to a specific embodiment of the present invention, preferably, the method for preparing the above-mentioned metallocene compound includes the following steps:

[0024] (1) At -30℃ to -10℃, p-toluenesulfonyl chloride was added to a pyridine solution of a diol monoether and reacted for 0.5-1h. Then the temperature was raised to 0-10℃ and reacted for 3-5h to obtain the first intermediate.

[0025] (2) Using a protective gas, the first intermediate obtained in step (1) is added to the CpNa solution at -10℃ to 10℃ and reacted for 3-5 hours to obtain the second intermediate.

[0026] (3) Using a protective gas, sodium and tetrahydrofuran were added to the reaction vessel, and the second intermediate was added under ice bath conditions. The reaction was carried out for 12-24 hours to obtain the third intermediate.

[0027] (4) Under the protection of a protective gas, the solution of MCl4 reacts with the third intermediate at -25°C to -45°C for 20-50 minutes, then the temperature is raised to 20-40°C and the reaction is carried out for 12-24 hours to obtain the metallocene compound.

[0028] According to a specific embodiment of the present invention, preferably, in step (1), p-toluenesulfonyl chloride is added at -25°C to -10°C for reaction, more preferably at -20°C to -15°C.

[0029] According to a specific embodiment of the present invention, preferably, in step (2), the first intermediate obtained in step (1) is added to the CpNa solution at -5°C to 5°C to carry out the reaction.

[0030] According to a specific embodiment of the present invention, preferably, in step (3), the reaction time is 18-24 hours.

[0031] According to a specific embodiment of the present invention, preferably, in step (4), the molar ratio of the third intermediate to MCl4 is 1-1.5:1, more preferably 1.15-1.35:1.

[0032] According to a specific embodiment of the present invention, preferably, in step (4), the solution of the third intermediate or the solution of MCl4 is added to the solution of the third intermediate at a temperature of -25°C to -35°C; more preferably, the temperature is -25°C to -30°C.

[0033] According to a specific embodiment of the present invention, preferably, in step (4), after the temperature is raised to 25°C, the reaction is carried out for 18-24 hours.

[0034] According to a specific embodiment of the present invention, preferably, the catalytic activity of the metallocene compound is ≥4.0 × 10⁻⁶. 5 gPOE / mol M h.

[0035] According to a specific embodiment of the present invention, the preparation method of the above-mentioned metallocene compound includes the following specific steps:

[0036] (1) Preparation of R2OR1OTs

[0037] In a three-necked flask equipped with a stirrer, glycol monomethyl ether and pyridine were added sequentially. p-Toluenesulfonyl chloride was slowly added at -30°C to -10°C, and the reaction was maintained at -30°C to -10°C for 30 minutes. The temperature was then raised to 0°C and the reaction was carried out for 4 hours. After standing, water was added, and the pH was adjusted to 2 with hydrochloric acid. The organic phase was separated, and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed sequentially with saturated sodium carbonate, saturated brine, and distilled water. The mixture was dried over anhydrous magnesium sulfate. After filtration, low-boiling-point substances were removed under reduced pressure to obtain R2OR1OTs.

[0038] (2) Preparation of CpR1OR2

[0039] Under argon protection, a THF solution containing CpNa was added to a stirred reaction flask. R2OR1OTs were slowly added dropwise at 0°C. After the addition was complete, the reaction was stirred for 4 hours. Ice water was added, and the mixture was stirred until the precipitate dissolved completely. The mixture was allowed to stand and separate into layers. The organic phase was separated, and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed successively with saturated NaCl aqueous solution and distilled water. The mixture was dried over anhydrous magnesium sulfate. After filtration, the mixture was distilled under reduced pressure, and the fraction at 40°C / 3 mmHg was collected to obtain CpR1OR2.

[0040] (3) Synthesis of NaCpR1OR2

[0041] Under argon protection, sodium wire and THF were added to the reaction flask, and the mixture was cooled to 0°C in an ice-water bath. Under stirring and argon protection, CpR1OR2 was slowly added dropwise, and the reaction was stirred for 12-24 hours. Stirring was stopped, and the mixture was allowed to stand to obtain the supernatant NaCpR1OR2.

[0042] (4) Synthesis of CpCH2CH2OCH3MCl3

[0043] Under argon protection, CH2Cl2 was added to MCl4, stirred, and cooled to -25°C to -45°C in a liquid nitrogen-ethanol bath. Under argon protection, a standardized tetrahydrofuran solution of NaCpR1OR2 was slowly added dropwise. After the addition was complete, the reaction was stirred at -25°C to -45°C for 30 minutes, then the temperature was raised to 25°C, and the reaction was stirred for 12-24 hours. A small amount of n-hexane was added for washing, filtering, and the solvent was removed under vacuum. After recrystallization from dichloromethane and n-hexane, crystals were obtained to yield the metallocene compound CpCH2CH2OCH3MCl3.

[0044] The metallocene compound of Formula I of the present invention can be transformed into the structure of Formula II in the activated state.

[0045] The present invention also provides a random copolymer of ethylene and α-olefin, which is prepared by the above-mentioned method for preparing random copolymer of ethylene and α-olefin.

[0046] According to a specific embodiment of the present invention, preferably, the α-olefin includes one or more combinations of 1-hexene, 1-octene, and 1-decene.

[0047] According to a specific embodiment of the present invention, preferably, the random copolymer of ethylene and α-olefin is a random copolymer of ethylene and 1-octene (MAO can be selected as the co-catalyst), and the 1-octene insertion rate is ≥4%mol.

[0048] This invention synthesizes metallocene compounds using substituted cyclopentadiene ligands. The side-chain oxygen atoms of these ligands possess lone pair electron groups. When there is no steric hindrance around the central metal atom, the oxygen atoms of the substituted cyclopentadiene ligands can coordinate with the metal to form a configurationally confined structure, exhibiting a certain ability to catalyze olefin polymerization reactions. This invention has the following beneficial effects:

[0049] 1. The preparation method of the present invention uses metallocene compounds with different substituents introduced on the cyclopentadienyl ring, which can improve the catalyst performance, shorten the catalyst synthesis route, increase the product yield, reduce the economic cost, and effectively catalyze the preparation of random copolymers of ethylene and α-olefins.

[0050] 2. The random copolymer of ethylene and α-olefin prepared in this invention does not contain [OO] in its molecular chain, that is, there is no adjacent hexene segment. The octene molecule exists in the molecular chain in an isolated and random manner, and the microstructure is of type EEOEE. Detailed Implementation

[0051] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0052] Example 1

[0053] This embodiment provides a metallocene compound (C5H4-CH2CH2OCH3)ZrCl3, which is prepared by the following steps:

[0054] (1) In a 250 mL three-necked flask with a stirrer, 15.8 mL of ethylene glycol monomethyl ether and 40 mL of pyridine were added in sequence. 42.0 g of p-toluenesulfonyl chloride was slowly added at -25 °C and the reaction was maintained at -25 °C for 30 minutes. The temperature was raised to 0 °C and the reaction was carried out for 4 hours. The reaction solution was a viscous white suspension. After standing, 50 mL of water was added and the pH was adjusted to 2 with 4 mol / L hydrochloric acid. The organic phase was separated and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed in sequence with saturated sodium carbonate, saturated brine and distilled water. The solution was dried over anhydrous magnesium sulfate. After filtration, the low-boiling-point substances were removed under reduced pressure (70 °C, 4 mmHg) to obtain 34.3 g of a slightly yellow transparent liquid CH3OCH2CH2OTs, with a yield of 71.9%.

[0055] (2) Under argon protection, a THF solution containing 0.147 mol C5H5Na was added to a 250 mL stirred reaction flask. 33.8 g of CH3OCH2CH2OTs was slowly added dropwise at 0 °C. After the addition was complete, a large amount of precipitate formed. The reaction was stirred for 4 h. 50 mL of ice water was added, and the mixture was stirred until the precipitate dissolved completely. The mixture was allowed to stand and separate into layers. The organic phase was separated, and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed successively with saturated NaCl aqueous solution and distilled water to obtain a yellow transparent liquid. The liquid was dried over anhydrous magnesium sulfate. After filtration and vacuum distillation, the fraction at 40 °C / 3 mmHg was collected to obtain 8.49 g of a slightly yellow transparent liquid C5H5CH2CH2OCH3, with a yield of 46.6%. The NMR results were as follows: 1 H NMR (400MHz, CDCl3): δ5.78 (m, 5H), 2.03~2.39 (t, 2H), 3.39~3.55 (q, 2H), 3.36 (s, 3H);

[0056] (3) Under argon protection, 1.5 g of sodium wire and 35 mL of THF were added to the reaction flask, and the mixture was cooled to 0 °C in an ice-water bath. Under stirring and argon protection, 8.86 mmol of C5H5CH2CH2OCH3 was slowly added dropwise, and the reaction was stirred for 18 hours. Stirring was stopped, and the mixture was allowed to stand to obtain the supernatant NaC5H4CH2CH2OCH3. The concentration was determined to be 0.252 mol / L, and the yield was 99.5%.

[0057] (4) Under argon protection, 8 mmol of ZrCl4 was added to 10 mL of CH2Cl2 and stirred to form a white suspension. The suspension was then cooled to -40 °C in a liquid nitrogen-ethanol bath. Under argon protection, 10 mmol of a standardized tetrahydrofuran solution of MeOEtCpNa was slowly added dropwise. After the addition was complete, the mixture was stirred at -40 °C for 30 minutes, then the temperature was raised to 25 °C and stirred for 20 hours. A small amount of n-hexane was added for washing, and a precipitate appeared. The precipitate was filtered, and the solvent was removed under vacuum to obtain a solid powder. After recrystallization from dichloromethane and n-hexane, 1.72 g of metallocene compound crystals were obtained, with a yield of 67.1%. The NMR results were as follows: 1 H NMR (400MHz, CDCl3): δ5.58~6.32 (s, 4H), 2.38 (d, 2H), 1.5~2.0 (t, 2H), 3.79 (s, 3H).

[0058] Example 2

[0059] This embodiment provides a metallocene compound (Me4CpCH2CH2OCH3)TiCl3, which is prepared by the following steps:

[0060] (1) In a 250 mL three-necked flask with a stirrer, 15.8 mL of ethylene glycol monomethyl ether and 40 mL of pyridine were added in sequence. 42.0 g of p-toluenesulfonyl chloride was slowly added at -20 °C and the reaction was maintained at -20 °C for 30 minutes. The temperature was raised to 0 °C and the reaction was carried out for 4 hours. The reaction solution was a viscous white suspension. After standing, 50 mL of water was added and the pH was adjusted to 2 with 4 mol / L hydrochloric acid. The organic phase was separated and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed in sequence with saturated sodium carbonate, saturated brine and distilled water. The solution was dried over anhydrous magnesium sulfate. After filtration, the low-boiling-point substances were removed under reduced pressure (70 °C, 4 mmHg) to obtain 34.1 g of a slightly yellow transparent liquid CH3OCH2CH2OTs, with a yield of 71.5%.

[0061] (2) Under argon protection, a THF solution containing 0.147 mol Me4C5H1Na was added to a 250 mL stirred reaction flask. 33.8 g of CH3OCH2CH2OTs was slowly added dropwise at 0 °C. After the addition was complete, a large amount of precipitate formed. The reaction was stirred for 4 h. 50 mL of ice water was added, and the mixture was stirred until the precipitate dissolved completely. The mixture was allowed to stand and separate into layers. The organic phase was separated, and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed successively with saturated NaCl aqueous solution and distilled water to obtain a yellow transparent liquid. The liquid was dried over anhydrous magnesium sulfate. After filtration and vacuum distillation, the fraction at 40 °C / 3 mmHg was collected to obtain 12.6 g of a slightly yellow transparent liquid (Me)4C5H-CH2CH2OCH3, with a yield of 47.5%. The NMR results were as follows: 1 H NMR (400MHz, CDCl3): δ1.75~2.08 (s, 12H), 2.53~2.96 (m, 2H), 3.43 (m, 2H), 5.90~6.30 (s, 1H), 3.42~3.65 (s, 3H).

[0062] (3) Under argon protection, 1.5 g of sodium wire and 35 mL of THF were added to the reaction flask. The mixture was cooled to 0 °C in an ice-water bath. Under stirring and argon protection, 8.86 mmol of (Me)4C5H-CH2CH2OCH3 was slowly added dropwise. The reaction was stirred for 18 hours. Stirring was stopped and the mixture was allowed to stand. The supernatant NaMe4C5CH2CH2OCH3 was obtained. The concentration was determined to be 0.252 mol / L, and the yield was 99.5%.

[0063] (4) Under argon protection, 10 mmol of NaMe4C5CH2CH2OCH3 tetrahydrofuran solution was added to the reaction flask. 8.8 mmol of TiCl4 was slowly added dropwise at -25°C. After the addition was complete, the reaction was stirred at -25°C for 30 minutes, then the temperature was raised to 25°C and stirred for 24 hours. A small amount of n-hexane was added for washing, and a precipitate appeared. The precipitate was filtered, and the solvent was removed under vacuum to obtain a solid powder. Recrystallization from dichloromethane and n-hexane yielded 1.771 g of metallocene compound crystals, with a yield of 60.6%. The NMR results were as follows: 1 HNMR (400MHz, CDCl3): δ6.35-7.38 (m, 5H), 1.32 (s, 12H), 2.12~2.30 (t, 2H), 3.29~3.38 (q, 2H), 3.53~3.80 (s, 3H).

[0064] Example 3

[0065] This embodiment provides a metallocene compound (C9H6CH2CH2OCH3)TiCl3, which is prepared by the following steps:

[0066] (1) In a 250 mL three-necked flask with a stirrer, 15.8 mL of ethylene glycol monomethyl ether and 40 mL of pyridine were added in sequence. 42.0 g of p-toluenesulfonyl chloride was slowly added at -22 °C and the reaction was maintained at -22 °C for 30 minutes. The temperature was raised to 0 °C and the reaction was carried out for 4 hours. The reaction solution was a viscous white suspension. After standing, 50 mL of water was added and the pH was adjusted to 2 with 4 mol / L hydrochloric acid. The organic phase was separated and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed in sequence with saturated sodium carbonate, saturated brine and distilled water. The solution was dried over anhydrous magnesium sulfate. After filtration, the low-boiling-point substances were removed under reduced pressure (70 °C, 4 mmHg) to obtain 34.0 g of a slightly yellow transparent liquid CH3OCH2CH2OTs, with a yield of 71.2%.

[0067] (2) Under argon protection, a THF solution containing 0.147 mol C9H7Na was added to a 250 mL stirred reaction flask. 33.8 g of CH3OCH2CH2OTs was slowly added dropwise at 0 °C. After the addition was complete, a large amount of precipitate formed. The reaction was stirred for 4 h. 50 mL of ice water was added, and the mixture was stirred until the precipitate dissolved completely. The mixture was allowed to stand and separate into layers. The organic phase was separated, and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed successively with saturated NaCl aqueous solution and distilled water to obtain a yellow transparent liquid. The liquid was dried over anhydrous magnesium sulfate. After filtration and vacuum distillation, the fraction at 40 °C / 3 mmHg was collected to obtain 11.33 g of a slightly yellow transparent liquid C9H7CH2CH2OCH3, with a yield of 44.3%. The NMR results were as follows: 1H NMR (400MHz, CDCl3): δ7.46 (m, 7H), 2.50~2.70 (d, 2H), 3.20~3.40 (t, 2H), 3.60~3.70 (s, 3H).

[0068] (3) Under argon protection, 1.5 g of sodium wire and 35 mL of THF were added to the reaction flask and cooled to 0 °C in an ice-water bath. Under stirring and argon protection, 8.86 mmol of methoxyethyl-indene was slowly added dropwise and the reaction was stirred for 18 hours. Stirring was stopped and the mixture was allowed to stand to obtain the supernatant NaC9H6CH2CH2OCH3, with a concentration of 0.250 mol / L and a yield of 99.4%.

[0069] (4) Under argon protection, 10 mmol of NaC9H6CH2CH2OCH3 tetrahydrofuran solution was added to the reaction flask. 6.8 mmol of TiCl4 was slowly added dropwise at -25°C. After the addition was complete, the reaction was stirred at -25°C for 30 minutes, then the temperature was raised to 25°C and stirred for 24 hours. A small amount of n-hexane was added for washing, and a precipitate appeared. The precipitate was filtered, and the solvent was removed under vacuum to obtain a solid powder. Recrystallization from dichloromethane and n-hexane yielded 1.25 g of metallocene compound crystals, with a yield of 66.4%. NMR results were as follows: 1 H NMR (400MHz, CDCl3): δ8.19 (m, 6H), 2.45~3.00 (m, 4H), 3.65~3.80 (s, 3H).

[0070] Example 4

[0071] This embodiment provides a metallocene compound (CpCH2CH2OCH3)TiCl3, which is prepared by the following steps:

[0072] (1) In a 250 mL three-necked flask with a stirrer, 15.8 mL of ethylene glycol monomethyl ether and 40 mL of pyridine were added in sequence. 42.0 g of p-toluenesulfonyl chloride was slowly added at -25 °C and the reaction was maintained at -25 °C for 30 minutes. The temperature was raised to 0 °C and the reaction was carried out for 4 hours. The reaction solution was a viscous white suspension. After standing, 50 mL of water was added and the pH was adjusted to 2 with 4 mol / L hydrochloric acid. The organic phase was separated and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed in sequence with saturated sodium carbonate, saturated brine and distilled water. The solution was dried over anhydrous magnesium sulfate. After filtration, the low-boiling-point substances were removed under reduced pressure (70 °C, 4 mmHg) to obtain 33.8 g of a slightly yellow transparent liquid CH3OCH2CH2OTs, with a yield of 70.9%.

[0073] (2) Under argon protection, a THF solution containing 0.147 mol C5H5Na was added to a 250 mL stirred reaction flask. 33.8 g of CH3OCH2CH2OTs was slowly added dropwise at 0 °C. After the addition was complete, a large amount of precipitate formed. The reaction was stirred for 4 h. 50 mL of ice water was added, and the mixture was stirred until the precipitate dissolved completely. The mixture was allowed to stand and separate into layers. The organic phase was separated, and the aqueous phase was extracted with diethyl ether. The organic phases were combined and washed successively with saturated NaCl aqueous solution and distilled water to obtain a yellow transparent liquid. The liquid was dried over anhydrous magnesium sulfate. After filtration and vacuum distillation, the fraction at 40 °C / 3 mmHg was collected to obtain 8.2 g of a slightly yellow transparent liquid C5H5CH2CH2OCH3, with a yield of 45.0%. The NMR results were as follows: 1 H NMR (400MHz, CDCl3): δ5.88 (m, 5H), 2.03~2.39 (m, 2H), 3.39~3.55 (s, 3H), 3.74 (s, 2H).

[0074] (3) Under argon protection, 1.5 g of sodium wire and 35 mL of THF were added to the reaction flask, and the mixture was cooled to 0 °C in an ice-water bath. Under stirring and argon protection, 8.86 mmol of C5H5CH2CH2OCH3 was slowly added dropwise, and the reaction was stirred for 18 hours. Stirring was stopped, and the mixture was allowed to stand to obtain the supernatant NaC5H4CH2CH2OCH3. The concentration was determined to be 0.252 mol / L, and the yield was 99.5%.

[0075] (4) Under argon protection, 10 mmol of NaC5H4CH2CH2OCH3 tetrahydrofuran solution was added to the reaction flask. 7.5 mmol of TiCl4 was slowly added dropwise at -25°C. After the addition was complete, the reaction was stirred at -25°C for 30 minutes, then the temperature was raised to 25°C and stirred for 24 hours. A small amount of n-hexane was added for washing, and a precipitate appeared. The precipitate was filtered, and the solvent was removed under vacuum to obtain a solid powder. Recrystallization from dichloromethane and n-hexane yielded 1.389 g of metallocene compound crystals, with a yield of 67.0%. The NMR results were as follows: 1 HNMR (400MHz, CDCl3): δ5.83~6.42(s,4H), 2.36(m,2H), 1.6~1.9(t,2H), 3.46(s,3H).

[0076] Catalytic olefin polymerization

[0077] Example 5

[0078] This embodiment uses a metallocene compound (C5H4-CH2CH2 OCH3)ZrCl3 as a catalyst for the copolymerization of ethylene and 1-octene, which includes the following steps:

[0079] Before the reaction, the reactor was preheated under vacuum to 80°C. Argon gas was then used to flush the reactor three times, and the temperature was maintained constant. The following materials were added in a glove box: 10 μmol of metallocene compound, 100 mL of toluene, 8 mL of MAO (aluminum-zirconium ratio 1194:1), and 25 mL of 1-octene. After adding the materials through the feeder, the ethylene pressure was set to 0.6 MPa. After reacting for 30 minutes, the ethylene inlet valve was closed, and the reactor was cooled by opening the cooling water. The reactor liner was removed, and the product was poured into a beaker. Hydrochloric acid-ethanol solution was added to terminate the reaction. The polymer was first repeatedly rinsed with hydrochloric acid-ethanol solution to dissolve the residual aluminum salt, then washed three more times with deionized water. Finally, it was placed in a vacuum drying oven and dried at 60°C to constant weight, yielding 3.15 g of solid. The catalytic activity of the metallocene compound was calculated to be 6.3 × 10⁻⁶. 5 g / (mol·Zr·h), based on polymer 13 C-NMR spectroscopy calculations showed that the 1-octene insertion rate in the copolymer was 5.68%.

[0080] Example 6

[0081] This embodiment uses a metallocene compound (CpCH2CH2OCH3)TiCl3 as a catalyst for the copolymerization of ethylene and 1-octene, which includes the following steps:

[0082] Before the reaction, the reactor was preheated under vacuum to 80°C. Argon gas was then used to flush the reactor three times, and the temperature was maintained constant. The following materials were added in a glove box: 10 μmol of metallocene compound, 100 mL of toluene, 6.7 mL of MAO (i.e., an aluminum-titanium ratio of 1000:1), and 30 mL of 1-octene. After adding the materials through the feeder, the ethylene pressure was set to 0.6 MPa. After reacting for 30 minutes, the ethylene inlet valve was closed, and the reactor was cooled by opening the cooling water. The reactor liner was removed, and the product was poured into a beaker. Hydrochloric acid-ethanol solution was added to terminate the reaction. The polymer was first repeatedly rinsed with hydrochloric acid-ethanol solution to dissolve the residual aluminum salt, then washed three more times with deionized water. Finally, it was placed in a vacuum drying oven and dried at 60°C to constant weight, yielding 2.35 g of solid. The catalytic activity of the metallocene compound was calculated to be 4.7 × 10⁻⁶. 5 g / (mol·Ti·h), based on polymer 13 C-NMR spectroscopy analysis revealed an 1-octene insertion rate of 4.12% in the copolymer.

[0083] Example 7

[0084] This embodiment uses a metallocene compound (Me4CpCH2CH2OCH3)TiCl3 as a catalyst for the copolymerization of ethylene and 1-octene, which includes the following steps:

[0085] Before the reaction, the reactor was preheated under vacuum to 80°C. Argon gas was then used to flush the reactor three times, and the temperature was maintained constant. The following materials were added in a glove box: 10 μmol of metallocene compound, 100 mL of toluene, 6.7 mL of MAO (i.e., an aluminum-titanium ratio of 1000:1), and 25 mL of 1-octene. After adding the materials through the feeder, the ethylene pressure was set to 0.6 MPa. After reacting for 30 minutes, the ethylene inlet valve was closed, and the reactor was cooled by opening the cooling water. The reactor liner was removed, and the product was poured into a beaker. Hydrochloric acid-ethanol solution was added to terminate the reaction. The polymer was first repeatedly rinsed with hydrochloric acid-ethanol solution to dissolve the residual aluminum salt, then washed three more times with deionized water. Finally, it was placed in a vacuum drying oven and dried at 60°C to constant weight, yielding 3.66 g of solid. The catalytic activity of the metallocene compound was calculated to be 7.32 × 10⁻⁶. 5 g / (mol·Ti·h), based on polymer 13 C-NMR spectroscopy analysis revealed an 1-octene insertion rate of 4.63% in the copolymer.

[0086] Example 8

[0087] This embodiment uses a metallocene compound (C9H6CH2CH2OCH3)TiCl3 as a catalyst for the copolymerization of ethylene and 1-octene, which includes the following steps:

[0088] Before the reaction, the reactor was preheated under vacuum to 80°C. Argon gas was then used to flush the reactor three times, and the temperature was maintained constant. The following materials were added in a glove box: 10 μmol of metallocene compound, 100 mL of toluene, 6.7 mL of MAO (i.e., an aluminum-titanium ratio of 1000:1), and 25 mL of 1-octene. After adding the materials through the feeder, the ethylene pressure was set to 0.6 MPa. After reacting for 30 minutes, the ethylene inlet valve was closed, and the reactor was cooled by opening the cooling water. The reactor liner was removed, and the product was poured into a beaker. Hydrochloric acid-ethanol solution was added to terminate the reaction. The polymer was first repeatedly rinsed with hydrochloric acid-ethanol solution to dissolve the residual aluminum salt, then washed three more times with deionized water. Finally, it was placed in a vacuum drying oven and dried at 60°C to constant weight, yielding 4.03 g of solid. The catalytic activity of the metallocene compound was calculated to be 8.06 × 10⁻⁶. 5 g / (mol·Ti·h), based on polymer 13 C-NMR spectroscopy analysis revealed an 1-octene insertion rate of 4.07% in the copolymer.

[0089] Comparative Example 1

[0090] This comparative example uses metallocene compound (C5H4-CH2CH2 OCH3) ZrCl3 to catalyze the copolymerization of ethylene and 1-octene. Except for the MAO content of 4 mL (i.e., the aluminum-titanium ratio of 600:1), the rest is the same as in Example 5.

[0091] A total of 1.10 g of solid was obtained, and the catalytic activity of the metallocene compound was calculated to be 2.2 × 10⁻⁶. 5 g / (mol·Zr·h), the 1-octene insertion rate in the copolymer is 5.35%.

[0092] Comparative Example 2

[0093] This comparative example uses metallocene compound (C5H4-CH2CH2 OCH3)ZrCl3 to catalyze the copolymerization of ethylene and 1-octene. Except for the reaction temperature of 40°C, the rest is the same as in Example 5.

[0094] A total of 0.63 g of solid was obtained, and the catalytic activity of the metallocene compound was calculated to be 1.26 × 10⁻⁶. 5 g / (mol·Zr·h), the 1-octene insertion rate in the copolymer is 5.15%.

[0095] Comparative Example 3

[0096] This comparative example uses metallocene compound (C9H6CH2CH2OCH3)TiCl3 to catalyze the copolymerization of ethylene and 1-octene. Except for the amount of 1-octene used (15 mL, where the volume of the long-chain α-olefin accounts for 12.3% of the total volume of the reactant system), the rest is the same as in Example 8.

[0097] A total of 2.63 g of solid was obtained, and the catalytic activity of the metallocene compound was calculated to be 5.26 × 10⁻⁶. 5 g / (mol·Ti·h), the 1-octene insertion rate in the copolymer is 2.01%.

Claims

1. A method for preparing a random copolymer of ethylene and α-olefin, comprising the following steps: Ethylene and α-olefin were reacted at 80-100°C in the presence of metallocene compounds and a co-catalyst to obtain a random copolymer of ethylene and α-olefin. The co-catalyst includes organoaluminum; The metallocene compound has the structure shown in Formula I or Formula II: In Formula I, M is selected from Zr or Ti, Cp is selected from cadmium, substituted cadmium, indene or substituted indene; R1 is selected from C2-C4 alkylene and its derivatives; R2 is selected from C1-C4 alkyl and its derivatives. In Formula II, M is selected from Zr or Ti, Cp is selected from cadmium, substituted cadmium, indene or substituted indene; R1 is selected from C2-C4 alkylene and its derivatives; R2 is selected from C1-C4 alkyl and its derivatives. The molar ratio of aluminum in the co-catalyst to M in the metallocene compound is 800-1500.

2. The preparation method according to claim 1, wherein, The α-olefin accounts for more than 15% of the total volume of the reactant system.

3. The preparation method according to claim 1, wherein, In Formula I, R1 is selected from C2-C4 alkylene groups; R2 is selected from C1-C4 alkyl groups.

4. The preparation method according to claim 1, wherein, In Formula I, Cp is selected from cyclohexane, methylcyclohexane, butylcyclohexane, and indene.

5. The preparation method according to claim 1, wherein, In Formula I, R1 is selected from ethylene, propylene, and butylene; R2 is selected from methyl, ethyl, propyl, and butyl.

6. The preparation method according to claim 1, wherein, The metallocene compound is prepared by the following steps: (1) At -30℃ to -10℃, p-toluenesulfonyl chloride was added to a pyridine solution of a diol monoether and reacted for 0.5-1h. Then the temperature was raised to 0-10℃ and reacted for 3-5h to obtain the first intermediate. (2) Using a protective gas, the first intermediate obtained in step (1) is added to the CpNa solution at -10℃ to 10℃ and reacted for 3-5 hours to obtain the second intermediate. (3) Using a protective gas, sodium and tetrahydrofuran were added to the reaction vessel, and the second intermediate was added under ice bath conditions. The reaction was carried out for 12-24 hours to obtain the third intermediate. (4) Under the protection of a protective gas, the solution of MCl4 reacts with the third intermediate at -25°C to -45°C for 20-50 minutes, then the temperature is raised to 20-40°C and the reaction is carried out for 12-24 hours to obtain the metallocene compound.

7. The preparation method according to claim 6, wherein, In step (1), p-toluenesulfonyl chloride is added at -25°C to -10°C to carry out the reaction.

8. The preparation method according to claim 6, wherein, In step (2), the first intermediate obtained in step (1) is added to the CpNa solution at -5℃ to 5℃ to carry out the reaction.

9. The preparation method according to claim 6, wherein, In step (4), the molar ratio of the third intermediate to MCl4 is 1-1.5:

1.

10. The preparation method according to claim 6, wherein, In step (4), at a temperature of -25°C to -35°C, a solution of the third intermediate is added to a solution of MCl4 or a solution of MCl4 is added to a solution of the third intermediate.

11. The preparation method according to claim 6, wherein, In step (4), after raising the temperature to 25°C, the reaction is carried out for 18-24 hours.

12. A random copolymer of ethylene and α-olefin, prepared by the method according to any one of claims 1-11.

13. The random copolymer of ethylene and α-olefin according to claim 12, wherein, The random copolymer of ethylene and α-olefin is a random copolymer of ethylene and 1-octene, and the 1-octene insertion rate of the random copolymer of ethylene and 1-octene is ≥4%mol.

Images