Method for preparing cycloolefin copolymer with controllable molecular weight

Abstract

The invention discloses a method for preparing a cycloolefin copolymer with controllable molecular weight. The method comprises the following steps: preparing alkylphenol and an alkylaluminoxane solution into a mixed solution; and mixing the cycloolefin solution with the mixed solution, putting into a polymerization bottle, introducing alpha-olefin, adding a catalyst, and carrying out addition polymerization to obtain the cycloolefin copolymer. According to the method, the molecular weight of the cycloolefin copolymer can be adjusted to a reasonable range, so that production of COC differentiated products under the same catalytic system becomes possible.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and specifically relates to a method for preparing a cycloolefin copolymer with controllable molecular weight. Background Art

[0002] Cycloolefin copolymer (COC) is a colorless and transparent polymer material prepared by addition polymerization of α-olefin and cycloolefin monomers under the action of a metallocene catalyst. Among them, ethylene is mainly used as the α-olefin, and norbornene and tetracyclododecene are mainly used as the cycloolefin. COC products have excellent properties such as high transparency, high gas and water barrier properties, and low dielectric constant. Therefore, they are widely used in the fields of food and drug packaging, medical devices, electronic devices, optical materials, etc. COC has been monopolized by Japan for a long time. In recent years, in order to break the monopoly of Japanese companies on COC products, domestic research on COC has become white-hot. At present, more than a dozen domestic companies are engaged in the R & D of COC, but most of them are committed to benchmarking the mainstream commercial grades of COC products of Japanese companies.

[0003] In summary, at present, it is necessary to break the monopoly of foreign companies on COC products and break through the technical barriers of the industry. However, the COC industry still has problems such as single products and limited applications, and it is difficult to produce products with different specifications and grades using the same catalytic system. Summary of the Invention

[0004] One of the purposes of the present invention is to provide a method for preparing a cycloolefin copolymer with controllable molecular weight, which can adjust the molecular weight of the cycloolefin copolymer to a reasonable range, making it possible to produce differentiated COC products under the same catalytic system.

[0005] To achieve the above-mentioned invention purpose, the present invention adopts the following technical solutions:

[0006] A method for preparing a cycloolefin copolymer with controllable molecular weight, the method comprising the following steps:

[0007] S1: Prepare a mixed solution by mixing an alkylphenol and an alkylaluminoxane solution;

[0008] S2: After mixing the cycloolefin solution and the mixed solution, put them into a polymerization flask, introduce α-olefin, add a catalyst, and carry out addition polymerization to obtain a cycloolefin copolymer.

[0009] In one embodiment of the present invention, the alkylaluminoxane in S1 is preferably a toluene solution of methylaluminoxane. Trimethylaluminum is produced as a by-product during the preparation of methylaluminoxane. Preferably, the mass fraction of toluene in the methylaluminoxane solution is 85-94%, the mass fraction of methylaluminoxane is 5-14%, and the mass fraction of trimethylaluminum is 1-5%.

[0010] In the present invention, the phenolic hydroxyl group in the alkylphenol can reversibly combine with by-products in the alkylaluminoxane solution, such as trimethylaluminum, thereby reducing the occurrence of chain transfer side reactions in the polymerization reaction, effectively increasing the molecular weight of the cycloolefin copolymer, and the molecular weight of the cycloolefin copolymer can be regulated by controlling the molar ratio of the alkylphenol to, for example, trimethylaluminum.

[0011] In one embodiment of the present invention, the alkylphenol described in S1 has the following general structural formula, where R1, R2, and R3 are respectively alkyl groups with 1 to 20 carbon atoms, preferably R1, R2, and R3 are respectively alkylphenols with 2 to 10 carbon atoms, and more preferably one or more of phenol, octylphenol, nonylphenol, p-tert-octylphenol, and 2,6-di-tert-butyl-p-cresol;

[0012]

[0013] In one embodiment of the present invention, the temperature for the preparation described in S1 is -25 to 0 °C.

[0014] In one embodiment of the present invention, the amount of the alkylphenol added in S1 is such that the molar ratio of it to trimethylaluminum in the alkylaluminoxane solution is 1 / 2 to 3 / 1, preferably 1 / 1 to 2 / 1.

[0015] In one embodiment of the present invention, the α-olefin described in S2 is an α-olefin with C2-C5, preferably ethylene and / or propylene, and more preferably ethylene.

[0016] In one embodiment of the present invention, the cycloolefin described in S2 is preferably one or more of norbornene, tetracyclododecene, dicyclopentadiene, and compounds containing dicyclopentadiene, and more preferably norbornene and / or tetracyclododecene.

[0017] In one embodiment of the present invention, the catalyst described in S2 is a metallocene catalyst, preferably dichlorodizirconocene.

[0018] In one embodiment of the present invention, the solvent in S2 is one or more of cyclohexane, n-hexane, methylcyclohexane, and toluene, preferably cyclohexane and / or toluene.

[0019] In one embodiment of the present invention, the feeding pressure of the α-olefin in S2 is 4 to 6 bar.

[0020] In one embodiment of the present invention, the temperature for the addition polymerization reaction described in S2 is 70 to 160 °C, preferably 90 to 130 °C.

[0021] Another object of the present invention is to provide a cycloolefin copolymer with controllable molecular weight.

[0022] A cycloolefin copolymer with controllable molecular weight, the copolymer is prepared by the above method, and the copolymer has the following structural characteristics:

[0023]

[0024] Among them, the values of n and m are selected so that the weight-average molecular weight of the copolymer is 10,000-100,000 g / mol, preferably 20,000-70,000 g / mol.

[0025] Compared with the prior art, the solution of the present invention has the following positive effects:

[0026] By adding the molecular weight regulator alkylphenol, the molecular weight of the cycloolefin copolymer can be significantly increased, and its molecular weight range can be effectively regulated by changing the addition amount, which can provide differentiated application products for downstream applications. In addition, the addition of the molecular weight regulator alkylphenol can increase the molecular weight distribution index of the cycloolefin copolymer, ensuring good processing performance while increasing its molecular weight. Specific embodiments

[0027] Combined with the following specific embodiments, the present invention will be further described. However, the present invention is not limited to the listed embodiments, but also includes all any known changes within the scope of the claims of the present invention.

[0028] The information of the materials used in the present invention is as follows:

[0029] 2,6-Di-tert-butyl-p-cresol, p-tert-octylphenol, 4-hexadecylphenol are purchased from Beijing Innochem Science & Technology Co., Ltd., with a purity of ≥99.9%;

[0030] The methylaluminoxane solution is purchased from GRACE, with a toluene mass fraction of 85-94%, a methylaluminoxane mass fraction of 5-14%, and a trimethylaluminum mass fraction of 1-5%;

[0031] Toluene is purchased from Kemiou Chemical Reagent Co., Ltd., with a purity of ≥99.0%;

[0032] Methylcyclohexane is purchased from Beijing Innochem Science & Technology Co., Ltd., with a purity of ≥99.0%;

[0033] n-Hexane is purchased from Aladdin Chemical Reagent Co., Ltd., with a purity of ≥99.0%;

[0034] Dichlorodizirconocene and ferrocene are purchased from Beijing Innochem Science & Technology Co., Ltd., with a purity of ≥99.9%

[0035] Norbornene, tetracyclododecene, and dicyclopentadiene are purchased from Beijing Innochem Science & Technology Co., Ltd., with a purity of ≥99.9%;

[0036] Ethylene and propylene are purchased from Qingdao Liquefied Air Co., Ltd., with a purity of ≥99.0%.

[0037] The information on the analysis and characterization methods and equipment of the present invention is as follows:

[0038] High-temperature gel permeation chromatography, instrument model GPC-IR, equipment manufacturer Polymer Char, test standard GBT36214.4-2018;

[0039] Differential scanning calorimetry, instrument model Mettler-Toledo DSC3, equipment manufacturer Mettler Toledo.

[0040] Example 1

[0041] Prepare a solution of norbornene in toluene with a concentration of 8 mol / l in the glove box for later use. Weigh 0.3 g of 2,6-di-tert-butyl-p-cresol and dissolve it in 3.5 ml of toluene. Place it in the glove box refrigerator and let it stand for 1 h. The temperature of the refrigerator is -21 °C. Take 1.5 ml of methylaluminoxane solution from the glove box refrigerator, where the mass fraction of toluene is 85%, the mass fraction of methylaluminoxane is 10%, and the mass fraction of trimethylaluminum is 5%. Drop the toluene solution of 2,6-di-tert-butyl-p-cresol into the methylaluminoxane solution with a syringe while stirring. After stirring evenly, the molar ratio of 2,6-di-tert-butyl-p-cresol to trimethylaluminum in the mixed solution is 3 / 2. Let it stand for 20 min for later use. Weigh 1.17 mg of dichlorodizirconocene in the glove box and dissolve it in 5 ml of toluene for later use. Take out the polymerization bottle from the oven and install it on the polymerization device. Set the temperature of the heating jacket to 110 °C and replace it with nitrogen 3 times. Take 10 ml of the norbornene toluene solution with a concentration of 8 mol / L and mix it evenly with the mixed solution of 2,6-di-tert-butyl-p-cresol and methylaluminoxane, then inject it into the polymerization bottle with a syringe. Preheat for 5 min and reduce the ethylene pressure to 4 bar through a pressure reducing valve. Inject the dichlorodizirconocene solution into the polymerization bottle, fully open the ethylene valve, and the polymerization reaction starts. After reacting for 3 min, close the ethylene valve to terminate the reaction. Take down the polymerization bottle, add ethanol to precipitate the polymer, and dry it in a vacuum oven at 80 °C to obtain the polymer.

[0042] Example 2

[0043] Prepare a solution of norbornene methylcyclohexane with a concentration of 8 mol / l in a glove box for later use. Weigh 0.1 g of 2,6-di-tert-butyl-p-cresol and dissolve it in 3.5 ml of methylcyclohexane. Place it in the glove box refrigerator and let it stand for 1 h. The temperature of the refrigerator is -21 °C. Take 1.5 ml of methylaluminoxane solution from the glove box refrigerator, where the mass fraction of toluene is 85%, the mass fraction of methylaluminoxane is 10%, and the mass fraction of trimethylaluminum is 5%. Drop the methylcyclohexane solution of 2,6-di-tert-butyl-p-cresol into the methylaluminoxane solution with a syringe while stirring. After stirring evenly, the molar ratio of 2,6-di-tert-butyl-p-cresol to trimethylaluminum in the mixed solution is 1 / 2. Let it stand for 20 min for later use. Weigh 1.17 mg of dichlorodizirconocene in the glove box and dissolve it in 5 ml of methylcyclohexane for later use. Take out the polymerization bottle from the oven and install it on the polymerization device. Set the temperature of the heating jacket to 110 °C and displace it with nitrogen 3 times. Take 10 ml of the norbornene methylcyclohexane solution with a concentration of 8 mol / L and mix it evenly with the mixed solution of 2,6-di-tert-butyl-p-cresol and methylaluminoxane, then inject it into the polymerization bottle with a syringe. Preheat for 5 min and reduce the propylene pressure to 4 bar through a pressure reducing valve. Inject the dichlorodizirconocene solution into the polymerization bottle, fully open the propylene valve, and the polymerization reaction starts. After reacting for 3 min, close the propylene valve to terminate the reaction. Take down the polymerization bottle, add ethanol to precipitate the polymer, and dry it in a vacuum oven at 80 °C to obtain the polymer.

[0044] Example 3

[0045] Prepare a solution of norbornene in toluene with a concentration of 8 mol / l in the glove box for later use. Weigh 0.53 g of 2,6-di-tert-butyl-p-cresol and dissolve it in 3.5 ml of toluene. Place it in the glove box refrigerator and let it stand for 1 h. The temperature of the refrigerator is 0 °C. Take 2.2 ml of methylaluminoxane solution from the glove box refrigerator, where the mass fraction of toluene is 90%, the mass fraction of methylaluminoxane is 7%, and the mass fraction of trimethylaluminum is 3%. Drop the toluene solution of 2,6-di-tert-butyl-p-cresol into the methylaluminoxane solution with a syringe while stirring. After stirring evenly, the molar ratio of 2,6-di-tert-butyl-p-cresol to trimethylaluminum in the mixed solution is 3 / 1. Let it stand for 20 min for later use. Weigh 0.74 mg of ferrocene in the glove box and dissolve it in 4.3 ml of toluene for later use. Take out the polymerization bottle from the oven and install it on the polymerization device. Set the temperature of the heating jacket to 160 °C and displace it with nitrogen three times. Take 10 ml of the norbornene toluene solution with a concentration of 8 mol / L and mix it evenly with the mixed solution of 2,6-di-tert-butyl-p-cresol and methylaluminoxane, then inject it into the polymerization bottle with a syringe. Preheat for 5 min and reduce the ethylene pressure to 4 bar through a pressure reducing valve. Inject the ferrocene solution into the polymerization bottle, fully open the ethylene valve, and the polymerization reaction starts. After reacting for 3 min, close the ethylene valve to terminate the reaction. Take down the polymerization bottle, add ethanol to precipitate the polymer, and dry it in a vacuum oven at 80 °C to obtain the polymer.

[0046] Example 4

[0047] Prepare a solution of tetracyclododecene in toluene with a concentration of 6 mol / l in the glove box for later use. Weigh 0.28 g of p-tert-butylphenol and dissolve it in 5.8 ml of toluene. Place it in the glove box refrigerator and let it stand for 1 h. The temperature of the refrigerator is -21 °C. Take 1.5 ml of methylaluminoxane solution from the glove box refrigerator, where the mass fraction of toluene is 85%, the mass fraction of methylaluminoxane is 10%, and the mass fraction of trimethylaluminum is 5%. Drop the toluene solution of p-tert-butylphenol into the methylaluminoxane solution with a syringe while stirring. After stirring evenly, the molar ratio of p-tert-butylphenol to trimethylaluminum in the mixed solution is 3 / 2. Let it stand for 20 min for later use. Weigh 0.74 mg of ferrocene in the glove box and dissolve it in 6 ml of toluene for later use. Take out the polymerization bottle from the oven and install it on the polymerization device. Set the temperature of the heating jacket to 160 °C and displace it with nitrogen three times. Take 6.7 ml of the tetracyclododecene toluene solution with a concentration of 6 mol / L and mix it evenly with the mixed solution of p-tert-butylphenol and methylaluminoxane, then inject it into the polymerization bottle with a syringe. Preheat for 5 min and reduce the ethylene pressure to 6 bar through a pressure reducing valve. Inject the ferrocene solution into the polymerization bottle, fully open the ethylene valve, and the polymerization reaction starts. After reacting for 3 min, close the ethylene valve to terminate the reaction. Take down the polymerization bottle, add ethanol to precipitate the polymer, and dry it in a vacuum oven at 80 °C to obtain the polymer.

[0048] Example 5

[0049] Prepare a solution of 3,4-dimethylcyclohexenemethylcyclohexane with a concentration of 8 mol / l in a glove box for later use. Weigh 0.28 g of p-tert-butylphenol and dissolve it in 3.5 ml of methylcyclohexane. Place it in the glove box refrigerator and let it stand for 1 h. The temperature of the refrigerator is 0 °C. Take 1.5 ml of methylaluminoxane solution from the glove box refrigerator, where the mass fraction of toluene is 85%, the mass fraction of methylaluminoxane is 10%, and the mass fraction of trimethylaluminum is 5%. Drop the methylcyclohexane solution of p-tert-butylphenol into the methylaluminoxane solution with a syringe while stirring. After stirring evenly, the molar ratio of p-tert-butylphenol to trimethylaluminum in the mixed solution is 3 / 2. Let it stand for 20 min for later use. Weigh 0.74 mg of ferrocene in the glove box and dissolve it in 5 ml of methylcyclohexane for later use. Take out the polymerization bottle from the oven and install it on the polymerization device. Set the temperature of the heating jacket to 110 °C and displace it with nitrogen 3 times. Take 10 ml of 3,4-dimethylcyclohexenemethylcyclohexane solution with a concentration of 8 mol / L and mix it evenly with the mixed solution of p-tert-butylphenol and methylaluminoxane, then inject it into the polymerization bottle with a syringe. Preheat for 5 min and reduce the ethylene pressure to 4 bar through a pressure reducing valve. Inject the ferrocene solution into the polymerization bottle, fully open the ethylene valve, and the polymerization reaction starts. After reacting for 3 min, close the ethylene valve to terminate the reaction. Take down the polymerization bottle, add ethanol to precipitate the polymer, and dry it in a vacuum oven at 80 °C to obtain the polymer.

[0050] Example 6

[0051] Prepare a norbornene n - hexane solution with a concentration of 8 mol / l in the glove box for later use. Weigh 0.38 g of 4 - hexadecylphenol and dissolve it in 3.5 ml of n - hexane. Place it in the glove box refrigerator and let it stand for 1 h. The temperature of the refrigerator is - 21 °C. Take 2.2 ml of methylaluminoxane solution from the glove box refrigerator, where the mass fraction of toluene is 90%, the mass fraction of methylaluminoxane is 7%, and the mass fraction of trimethylaluminum is 3%. Drop the n - hexane solution of 4 - hexadecylphenol into the methylaluminoxane solution with a syringe while stirring. After stirring evenly, the molar ratio of 4 - hexadecylphenol to trimethylaluminum in the mixed solution is 3 / 2. Let it stand for 20 min for later use. Weigh 1.17 mg of dichlorodizirconocene in the glove box and dissolve it in 4.3 ml of n - hexane for later use. Take out the polymerization bottle from the oven and install it on the polymerization device. Set the temperature of the heating jacket to 70 °C and displace it with nitrogen three times. Take 10 ml of the norbornene n - hexane solution with a concentration of 8 mol / L and mix it evenly with the mixed solution of 4 - hexadecylphenol and methylaluminoxane, then inject it into the polymerization bottle with a syringe. Preheat for 5 min and reduce the ethylene pressure to 6 bar through a pressure reducing valve. Inject the dichlorodizirconocene solution into the polymerization bottle, fully open the ethylene valve, and the polymerization reaction starts. After reacting for 3 min, close the ethylene valve to terminate the reaction. Take down the polymerization bottle, add ethanol to precipitate the polymer, and dry it in a vacuum oven at 80 °C to obtain the polymer.

[0052] Comparative Example 1

[0053] Compared with Example 1, the difference is that 2,6 - di - tert - butyl - p - cresol is not added.

[0054] Comparative Example 2

[0055] Compared with Example 2, the difference is that 2,6 - di - tert - butyl - p - cresol is not added in Step S1 but added in Step S2.

[0056] The products of this example are tested for their performance using national standards, and the results are shown in Table 1:

[0057] Table 1 Test Results of Examples and Comparative Examples

[0058]

[0059] It can be concluded from the test results that the addition of alkylphenol can indeed increase the molecular weight of the cycloolefin copolymer, improve its molecular weight distribution at the same time, and can regulate the molecular weight of the cycloolefin copolymer by adjusting the dosage; the addition sequence of alkylphenol also affects the molecular weight of the cycloolefin copolymer. Adding it in Step S1 can significantly increase the molecular weight of the cycloolefin copolymer, while adding it in Step S2 has the opposite effect.

Claims

1. A method for preparing a cycloolefin copolymer with controllable molecular weight, characterized in that, The method comprises the following steps: S1: Prepare a mixed solution from an alkylphenol and an alkylaluminoxane solution; S2: After mixing the cycloolefin solution with the mixed solution, put them into a polymerization flask, introduce an α-olefin, add a catalyst, and carry out addition polymerization to obtain a cycloolefin copolymer.

2. The method according to claim 1, wherein The alkylphenol described in S1 has the following general structural formula, where R1, R2, and R3 are respectively alkyl groups with 1 to 20 carbon atoms. Preferably, R1, R2, and R3 are respectively alkylphenols with 2 to 10 carbon atoms. More preferably, it is one or more of phenol, octylphenol, nonylphenol, p-tert-octylphenol, and 2,6-di-tert-butyl-p-cresol; And / or, the alkylaluminoxane described in S1 is preferably a toluene solution of methylaluminoxane. Preferably, the mass fraction of toluene in the methylaluminoxane solution is 85 to 94%, the mass fraction of methylaluminoxane is 5 to 14%, and the mass fraction of trimethylaluminum is 1 to 5%; And / or, the temperature for preparation in S1 is -25 to 0°C; And / or, the amount of alkylphenol added in S1 makes the molar ratio of it to trimethylaluminum in the alkylaluminoxane solution 1 / 2 to 3 / 1, preferably 1 / 1 to 2 / 1.

3. The method according to claim 1, wherein The α-olefin described in S2 is an α-olefin with C2-C5, preferably ethylene and / or propylene, and more preferably ethylene; And / or, the cycloolefin described in S2 is preferably one or more of norbornene, tetracyclododecene, dicyclopentadiene, and compounds containing dicyclopentadiene, and more preferably norbornene and / or tetracyclododecene; And / or, the catalyst described in S2 is a metallocene catalyst, preferably dichlorodizirconocene; And / or, the solvent in S2 is one or more of cyclohexane, n-hexane, methylcyclohexane, and toluene, preferably methylcyclohexane and / or toluene; And / or, the feeding pressure of the α-olefin in S2 is 4 to 6 bar; And / or, the temperature for carrying out the addition polymerization reaction in S2 is 70 to 160°C, preferably 90 to 130°C.

4. A cycloolefin copolymer with controllable molecular weight, which is prepared by the method described in any one of claims 1-3, characterized in that, The copolymer has the following structural characteristics: Wherein, the values of n and m are selected so that the weight-average molecular weight of the copolymer is 10,000 to 100,000 g / mol, preferably 20,000 to 70,000 g / mol.

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