Metallocene catalyst system, polyisobutene and preparation method thereof

Abstract

The invention discloses a metallocene catalyst system, polyisobutene and a preparation method thereof. The metallocene catalyst system comprises a component A, a component B, a component C and a component D, the component A is a metallocene complex; the component B is borate; the component C is aluminum alkyl; and the component D is selected from alkyl ether with 2-8 carbon atoms. The metallocene catalyst system used in the method is high in catalytic activity, raw materials are cheap and easy to obtain, and the production cost can be greatly reduced. Compared with a BF3 catalyst system, the catalyst system provided by the invention is non-toxic, harmless, pollution-free and corrosion-free, and can effectively solve the technical problems of toxicity, harmlessness, corrosion, pollution and the like in the traditional technical route, so that the operation environment is improved, and the human health is guaranteed. According to the invention, under the mild condition of 0-80 DEG C, that is, conventional cooling water is adopted to remove heat, polyisobutene with narrow distribution and medium molecular weight can be synthesized, and the problem of low-temperature reaction in traditional cationic polymerization is solved.

Description

Technical Field

[0001] The invention relates to a metallocene catalyst system, polyisobutylene and a preparation method thereof. Background Art

[0002] With the full promotion of ethanol gasoline in China, MTBE is prohibited from being used as a gasoline additive. A large number of MTBE production facilities have switched to producing isobutylene, resulting in a serious surplus of isobutylene resources. How to make high-quality use of isobutylene resources and convert them into high-value-added products is a major problem facing the transformation and upgrading of the domestic refining and chemical industry.

[0003] Medium molecular weight polyisobutylene usually refers to polyisobutylene with a number average molecular weight (Mn) of 10,000 to 50,000. It has good air tightness, aging resistance, corrosion resistance, and good compatibility with most polymers. It is widely used in bonding, sealing materials, anti-vibration materials, pressure-sensitive adhesives, grease thickeners, filling materials and chewing gum bases. In particular, with the rapid growth in the demand for hollow glass, chewing gum bases and adhesives, the medium molecular weight polyisobutylene consumer market has shown a good development trend. Using isobutylene as raw material to produce medium molecular weight polyisobutylene is an effective way to utilize isobutylene resources in a high-quality manner.

[0004] Metallocene has a single active center, which can make the obtained olefin polymer have better uniformity during the catalytic polymerization process, so the polymer product has the characteristics of narrow distribution. In addition, metallocene catalysts have the characteristics of flexible and adjustable structure, and the catalytic reaction performance can be improved by regulating its spatial effect and electronic effect.

[0005] Therefore, metallocene-catalyzed isobutylene polymerization is currently commonly used to produce polyisobutylene materials. Summary of the invention

[0006] In order to increase the method of producing polyisobutylene, the embodiment of the present invention provides a novel metallocene catalyst system, which can catalyze the polymerization of isobutylene under mild conditions to produce a polyisobutylene with narrow distribution and medium molecular weight.

[0007] As one aspect of the present invention, it relates to a metallocene catalyst system, which includes four components A, B, C, and D; component A is a metallocene complex; component B is a borate; component C is an alkyl aluminum; and component D is selected from dialkyl ethers with 2 to 8 carbon atoms.

[0008] In any specific embodiment, the component A is a bridged or non-bridged metallocene complex; the structural formula (I) of the bridged component A is Cp' n (X')MX m The general structural formula (II) of the non-bridging component A is Cp' nMX m ;

[0009] In formula (I) and (II), Cp' is selected from substituted or unsubstituted cyclopentadienyl, indenyl, fluorenyl; M is an active center metal; X is selected from halogen, alkyl, alkoxy, amino or acid radical; n is 1 or 2, and m is an integer satisfying the valence state of M.

[0010] In any specific embodiment, in the Cp', the substituent is selected from one or more of an aryloxy group, a substituted aryloxy group, an alkyl group, an alkoxy group, and a silane group.

[0011] In any specific embodiment, the substituted aryloxy group is selected from aryloxy groups substituted by alkyl groups having 1 to 18 carbon atoms.

[0012] In any specific embodiment, the M is selected from one of Ti, Zr or Hf.

[0013] In any specific embodiment, when component A is a bridged metallocene complex, X' is selected from one of SiR2, CR2, SiR2SiR2, CR2CR2, CR=CR or (CR3)2Si.

[0014] In any specific embodiment, R is hydrogen; or R is selected from an alkyl group, an aryl group, a silyl group, a halogenated alkyl group or a halogenated aryl group having less than 20 carbon atoms.

[0015] In any specific embodiment, the component A is selected from one of Cp'TiX2, Cp'ZrX2, Cp'2ZrX2, Cp'2HfX2, and Cp'2(CR3)2SiZrX2.

[0016] In any specific embodiment, the component B is selected from Ph3CB(C6F5)4, PhNMe2HB(C6F5)4, B(C6F5)3 or [(C a H 2a+1 )2NH(C b H2 b+1 )][B(C6F5)4], wherein 2≤a≤20, 1≤b≤20, and a and b are both integers.

[0017] Furthermore, the component B is selected from one of Ph3CB(C6F5)4, PhNMe2HB(C6F5)4 or B(C6F5)3.

[0018] In any specific embodiment, the component C is a trialkylaluminum; the trialkylaluminum is selected from one of trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, tri-n-decylaluminum and tri-n-dodecylaluminum.

[0019] Furthermore, the component C is selected from one of triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-n-hexylaluminum or tri-n-octylaluminum.

[0020] In any specific embodiment, the component D is selected from one of methyl ether, isopropyl ether, n-butyl ether or methyl tert-butyl ether.

[0021] As another aspect of the present invention, it relates to the use of the above metallocene catalyst system in catalyzing the polymerization of isobutylene.

[0022] As another aspect of the present invention, it relates to a method for preparing polyisobutylene. When preparing polyisobutylene, the method uses the above-mentioned metallocene catalyst system to catalyze the polymerization of isobutylene.

[0023] Specifically, the following steps are included:

[0024] S1. Refining of raw materials and solvents

[0025] After sieving isobutylene and solvent, drying and dehydration are performed;

[0026] S2, Aggregation

[0027] Under dry and oxygen-free conditions, add solvent, isobutylene and component C in sequence, stir and mix, increase the temperature, and then add components A, B, and D to participate in polymerization to obtain a crude polymerization product; S3, crude product pretreatment

[0028] The crude polymer product obtained in S2 is acid-washed, and then alkali-washed and water-washed in sequence until the water washing liquid is neutral, and then allowed to stand for stratification, and the upper oil phase is taken;

[0029] S4. Purification of polymer products

[0030] The oil phase product is distilled under reduced pressure to obtain a polyisobutylene product.

[0031] In any specific embodiment, in S1, the solvent is selected from one or more of C2-C12 straight-chain alkanes, C4-C12 isomeric alkanes, C3-C8 cycloalkanes, benzene or substituted benzenes.

[0032] In any specific embodiment, in S2, the polymerization temperature is 0-100°C, the time is 0.1-4h, and the pressure is 0-2MPa.

[0033] In any specific embodiment, in S2, the molar ratio of the component A to the component B is 1:(0.5-3); the molar ratio of the component A to the component C is 1:(1-60); the molar ratio of the component A to the component D is 1:(0.01-1).

[0034] Furthermore, the molar ratio of the component A to the component B is 1:(1-2.5); the molar ratio of the component A to the component C is 1:(2-40); and the molar ratio of the component A to the component D is 1:(0.05-1).

[0035] In any specific embodiment, in S2, the mass ratio of the isobutylene to the solvent is (2-12):1.

[0036] In any specific embodiment, in S2, the molar ratio of isobutylene to component A is (1×10 4 ~1×10 7 ):1.

[0037] Further, the molar ratio of the isobutylene to the component A is (1×10 5 ~1×10 7 ):1.

[0038] In any specific embodiment, in S4, the pressure condition of the reduced pressure distillation is -0.1 to -0.5 MPa, and the temperature is 150 to 200°C.

[0039] As another aspect of the present invention, it relates to polyisobutylene, which is prepared by the above method.

[0040] In any specific embodiment, the number average molecular weight of the polyisobutylene is 5000-100000, and the molecular weight distribution is 1-2.5.

[0041] Furthermore, the number average molecular weight of the polyisobutylene is 10,000 to 70,000, and the molecular weight distribution is 1 to 2.2.

[0042] The metallocene catalyst system used in the present invention has high catalytic activity and the raw materials are cheap and easy to obtain, which can greatly reduce the production cost. Compared with the BF3 catalyst system, the catalyst system provided by the present invention is non-toxic, harmless, non-polluting and non-corrosive, and can effectively solve the technical problems of toxicity, harm, corrosion, pollution and the like existing in the traditional technical route, thereby improving the operating environment and ensuring human health.

[0043] The invention can synthesize polyisobutylene with narrow distribution and medium molecular weight under mild conditions of 0-80°C, that is, using conventional cooling water to remove heat, thereby solving the low-temperature reaction problem existing in traditional cationic polymerization.

[0044] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 This is the H-NMR spectrum of the polyisobutylene product prepared in Example 1 of the present invention;

[0046] Figure 2 This is a gel chromatogram of the polyisobutylene product prepared in Example 1 of the present invention;

[0047] Figure 3 The gel chromatograms of the polyisobutylene products prepared in Examples 2 to 8 of the present invention are shown in the order of a to g;

[0048] Figure 4 The gel chromatograms of the polyisobutylene products prepared in Comparative Examples 1 to 6 of the present invention are shown in the order of h to m. DETAILED DESCRIPTION

[0049] When the inventor explored the synthesis method of polyisobutylene, he found that in current industrial production, Lewis acids such as BF3 and AlCl3 are usually used to catalyze isobutylene to polymerize and produce polyisobutylene products. The polymerization reaction needs to be carried out at a low temperature of -40°C through an ammonia evaporation and heat removal process. This process has high energy consumption, high viscosity of the reaction system, and is prone to blockage and wall adhesion, which shortens the production cycle. There are also problems such as hydrofluoric acid corrosion of the device and pollution of fluorine-containing wastewater discharge. Therefore, in recent years, the research on the synthesis of polyisobutylene has mainly focused on the development of metallocene catalyst systems.

[0050] However, metallocene-catalyzed isobutylene polymerization technology still has the problem of low-temperature reaction, and since metallocene catalysts cannot be recycled, the catalyst cost has become a key factor restricting its industrial application.

[0051] Andrew G. Carr et al. used zirconocene catalyst systems Cp2ZrMe2 and Cp2Zr(OH)2 / B(C6F5) to catalyze isobutylene homopolymerization and isobutylene / isoprene copolymerization to obtain medium-high molecular weight polyisobutylene. The reaction temperature was -30 to -78°C, and the product number average molecular weight (Mn) was 33,000 to 810,000 (Mw / Mn was 1.5 to 5). However, when the inventors used the data recorded in the literature for calculation, they found that the polymerization activity decreased significantly with increasing temperature, and the monomer conversion rate was less than 15% at -30°C. (Carr AG, Dawsor DM. Zirconiacenes as initiators for carbocationicisobutene home and opolymerizations [J]. Macromolecules, 1998, 31 (7): 2035-2040.)

[0052] Bochmann et al. used aluminocene catalyst system Cp2Al(μ-Me) / B(C6F5)3 to catalyze the polymerization of isobutylene to prepare high molecular weight polyisobutylene. The reaction temperature was -25 to -78°C, and the number average molecular weight (Mn) of the product was 289,000 to 1,340,000 (Mw / Mn was 1.6 to 3.4). However, the inventors found that the activity of the polymerization reaction decreased significantly with increasing temperature, and the monomer conversion rate was less than 2% at -25 to -30°C (Bochmann M, Dawson DM. The aluminocenium cation [Al(C5H5)2]+: a highly effective initiator for the cationic polymerization of isobutene [J]. Angewandte Chemie International Edition in English, 1996, 35 (19): 2226-2228.).

[0053] Patent US5448001 discloses a method for synthesizing medium molecular weight polyisobutylene at -40 to -20°C using isobutylene and / or mixed C4 as raw materials and BF3 / water, alcohol, alkyl-substituted phenol, and acid ether as catalysts, and the product Mn is 8000 to 25000. However, the inventor believes that this solution requires reaction at low temperature to inhibit chain transfer in order to obtain a product with a higher molecular weight.

[0054] Irina et al. used a catalyst system composed of AlCl3 and RnAlCl3 / ether to catalyze the polymerization of isobutylene at -20°C to prepare medium molecular weight polyisobutylene, and the product molecular weight was 6800-54700. However, the inventors found that the catalytic activity of the catalyst system was significantly reduced when preparing products with higher molecular weights, that is, when Mn was 54700, the monomer conversion rate was only 7%. (Vasilenko IV, Nikishev PA, Shiman DI, et al. Cationic polymerization of isobutylene in toluene: toward well-defined exo-olefin terminated medium molecular weight polyisobutylenes under mild conditions [J]. Polymer Chemistry, 2017, 8 (8): 1417-1425.)

[0055] In summary, in view of the fact that the prior art is not as good as the inventor's expectations, the inventor made the present invention through further research and development.

[0056] The present invention provides a method for synthesizing medium molecular weight polyisobutylene based on a novel metallocene catalyst system, wherein counter ions provided by an electron donor form a limiting effect on polymerization active centers, thereby effectively inhibiting chain transfer and isomerization side reactions during the polymerization process, enabling the polymerization chain to grow stably under relatively high temperature conditions, thereby realizing the synthesis of narrow distribution medium molecular weight polyisobutylene under mild conditions.

[0057] The present invention is further described below in conjunction with specific examples, and the protection scope of the present invention is not limited by the following examples. The sources of the materials mainly involved in the examples are shown in Table 1 below, and other materials not shown are conventional commercial products.

[0058] Table 1 Material source description

[0059]

[0060] The inventors have designed a special metallocene catalyst system to catalyze the polymerization of isobutylene to produce medium molecular weight polyisobutylene. The following are specific examples of the present invention. In the following examples of the present invention, the evaluation and analysis methods used are as follows:

[0061] (1) Agilent PL220 room temperature gel permeation chromatography was used to determine the molecular weight and molecular weight distribution of highly active polyisobutylene; the molecular weight of polyisobutylene products was measured in accordance with the relevant provisions of "HG / T 4787-2014 Medium Molecular Weight Polyisobutylene"; the molecular weight distribution of products was measured in accordance with the relevant provisions of "SH / T1759-2007 Determination of Molecular Weight Distribution of Solution Polymers by Gel Permeation Chromatography";

[0062] (2) The product structure is analyzed by hydrogen nuclear magnetic spectroscopy based on the characteristic H atom chemical shift peaks. The equipment used is a commercially available 400.13 MHz nuclear magnetic resonance spectrometer.

[0063] Example 1

[0064] The metallocene catalyst system provided in this embodiment includes the following components:

[0065] Component A: [2-(2,3,4,5-tetramethylcyclopentadienyl)-4-tert-butyl-6-tritylphenoxy]titanium dichloride; The synthesis method of component A refers to Huo Hang. Synthesis, characterization and catalytic properties of constrained geometry metallocene catalysts [D]. Jilin University, 2015.

[0066] Component B: Ph3CB(C6F5)4;

[0067] Component C: triisobutylaluminum;

[0068] Component D: methyl tert-butyl ether;

[0069] In the present embodiment, when preparing polyisobutylene, the amount of component A is 10 μmol, and the molar ratios of the remaining components are: B / A=2:1, C / A=50:1, D / A=1:10, toluene is used as the solvent in an amount of 60 ml, and isobutylene is 100 g.

[0070] The preparation method of this embodiment is carried out in a 500 ml reactor and specifically comprises the following steps:

[0071] S1. The molecular sieve is loaded into a drying tower, and isobutylene and toluene are respectively passed through the drying tower from bottom to top at a space velocity of 0.5 BV / h for dehydration treatment at normal temperature and pressure.

[0072] S2. Maintain the internal temperature of the reactor at 100°C, introduce high-purity nitrogen to raise the pressure in the reactor to 0.7Mpa, then exhaust the gas, and repeat the operation 3-5 times. Then evacuate the reactor to reduce the pressure in the reactor to 0.3Kpa, and then immediately introduce high-purity nitrogen to raise the pressure in the reactor to 0.7Mpa, and repeat the operation 3-5 times. After adjusting the temperature in the reactor to 40°C, add the solvent, isobutylene and component C (triisobutylaluminum) into the reactor, maintain the temperature and stir for 30 minutes, then add components A, B, and D to start the polymerization reaction, add 2ml of ethanol terminator after 1 hour, continue stirring for 30 minutes, and then stop the reaction;

[0073] S3. After the reaction is completed, the unreacted isobutylene monomer is discharged from the vent pipe, the reaction product is discharged from the bottom of the kettle and collected, the reaction product is washed with 30wt% dilute sulfuric acid, and then the reaction product is continuously alkali-washed or directly washed with water until neutral, and the reaction product is allowed to stand for stratification, and the upper oil phase is taken to obtain a polyisobutylene intermediate product containing a solvent and oligomers;

[0074] S4. The solvent was separated by distillation at normal pressure and 110° C., and then the by-product oligomers were separated by reduced pressure distillation at -0.1 to -0.05 MPa and 150 to 200° C. The remaining product was collected to obtain 91.2 g of polyisobutylene product.

[0075] The polyisobutylene product prepared in this embodiment 1 The results of HNMR (hydrogen nuclear magnetic spectrum) and GPC (gel chromatography) analysis are shown in the attached Figure 1 , as shown in 2. Figure 1 It can be seen that: the characteristic peaks of polyisobutylene α-H appear at chemical shifts δ4.64 and δ4.85, and the characteristic peaks of polyisobutylene β-H appear between chemical shifts δ5-5.4. Therefore, the inventors believe that the obtained product is polyisobutylene. Figure 2 It can be seen that the product Mn is 34268 and the molecular weight distribution is 1.87.

[0076] Example 2

[0077] The difference between the preparation method of this embodiment and that of embodiment 1 is that component A is replaced with biscyclopentadienyl zirconium dichloride, and 88 g of the product is obtained by distillation;

[0078] The gel chromatography analysis results of the product are shown in the attached Figure 3 As shown in (a), through Figure 3 (a) It can be seen that the product Mn is 19280 and the molecular weight distribution is 1.77.

[0079] Example 3

[0080] The difference between the preparation method of this embodiment and that of embodiment 1 is that component A is replaced with dimethylsilyl-bridged bis-indenyl zirconium dichloride, and 92 g of the product is obtained by distillation.

[0081] The gel chromatography analysis results of the product are shown in the attached Figure 3 As shown in (b), through Figure 3 (b) It can be seen that the product Mn is 16211 and the molecular weight distribution is 1.83.

[0082] Example 4

[0083] The difference between the preparation method of this embodiment and that of embodiment 1 is that component A is replaced with vinylbistetrahydroindenyl zirconium dichloride, and 82 g of the product is obtained by distillation;

[0084] The gel chromatography analysis results of the product are shown in the attached Figure 3 As shown in (c), through Figure 3 (c) It can be seen that the product Mn is 20416 and the molecular weight distribution is 1.79.

[0085] Example 5

[0086] The difference between the preparation method of this embodiment and that of embodiment 1 is that component A is replaced with dimethylsilyl-bridged bis-indenyl zirconium dichloride, and 78 g of the product is obtained by distillation.

[0087] The gel chromatography analysis results of the product are shown in the attached Figure 3 As shown in (d), through Figure 3 (d) It can be seen that the product Mn is 24925 and the molecular weight distribution is 1.73.

[0088] Example 6

[0089] The difference between the preparation method of this embodiment and that of embodiment 1 is that component A is replaced with isopropylidenecyclopentadienylfluorenylzirconium dichloride, and 75 g of the product is obtained by distillation;

[0090] The gel chromatography analysis results of the product are shown in the attached Figure 3 As shown in (e), through Figure 3(e) It can be seen that the product Mn is 19400 and the molecular weight distribution is 1.75.

[0091] Example 7

[0092] The difference between the preparation method of this embodiment and that of embodiment 1 is that component A is replaced with bis-indenyl zirconium dichloride, and 83 g of product is obtained by distillation;

[0093] The gel chromatography analysis results of the product are shown in the attached Figure 3 As shown in (f), through Figure 3 (f) It can be seen that the product Mn is 28449 and the molecular weight distribution is 1.71.

[0094] Example 8

[0095] The difference between the preparation method of this embodiment and that of embodiment 1 is that component A is replaced with bis(isopropylcyclopentadiene)hafnium dichloride, and 89 g of the product is obtained by distillation.

[0096] The gel chromatography analysis results of the product are shown in the attached Figure 3 As shown in (g), through Figure 3 (g) It can be seen that the product Mn is 21840 and the molecular weight distribution is 2.18.

[0097] The inventors selected a mono-titalocene catalytic system similar to the scheme of the present application (hereinafter referred to as "mono-titalocene"):

[0098] The catalytic polymerization of isobutylene was used to produce polyisobutylene as Comparative Example 1 of the present invention.

[0099] Comparative Example 1

[0100] The synthesis method of the mono-titanium cyclopentadiene catalyst system in this comparative example is prepared by referring to the relevant methods described in Barsan F, Karam AR, Parent MA, et al. Polymerization of isobutylene and the copolymerization of isobutylene and isoprene initiated by the metallocene derivative Cp*TiMe2(μ-Me)B(C6F5)3[J]. Macromolecules, 1998, 31(24): 8439-8447.

[0101] The preparation method of polyisobutylene in this comparative example is similar to that in Example 1, and specifically comprises the following steps: the amount of monotantalum is 10 μmol, B / Ti=2:1, toluene is used as solvent, the amount is 60 ml, isobutylene is 100 g, reacting at 40° C. for 1 h, separating the unreacted monomer after the reaction, releasing the reaction product, washing with acid, alkali and water in sequence until neutral, obtaining a colorless and transparent intermediate product, removing the solvent and oligomers by reduced pressure distillation, and finally obtaining 41 g of polyisobutylene product;

[0102] The GPC analysis results of the polyisobutylene product prepared in this comparative example are shown in the attached Figure 4 As shown in (h), through Figure 4 (h) It can be seen that the product Mn is 3898 and the molecular weight distribution is 2.1.

[0103] Comparative Example 2

[0104] The difference from Comparative Example 1 is that the solvent is replaced by hexane from toluene. Finally, 47 g of polyisobutylene product is obtained;

[0105] The GPC analysis results of the polyisobutylene product prepared in this comparative example are shown in the attached Figure 4 (i) as shown, through Figure 4 (i) It can be seen that the product Mn is 1691 and the molecular weight distribution is 3.7.

[0106] Comparative Example 3

[0107] The difference from Comparative Example 1 is that the amount of monotantalum is increased to 50 μmol. Finally, 78 g of polyisobutylene product is obtained;

[0108] The GPC analysis results of the polyisobutylene product prepared in this comparative example are shown in the attached Figure 4 As shown in (j), through Figure 4 (j) It can be seen that the product Mn is 2910 and the molecular weight distribution is 2.33.

[0109] The inventors also selected a rare earth scandium cyclopentadienyl catalyst system similar to the present application scheme (hereinafter referred to as "rare earth scandium cyclopentadienyl"):

[0110] The catalytic polymerization of isobutylene was used to produce polyisobutylene as Comparative Example 4 of the present invention.

[0111] Comparative Example 4

[0112] The synthesis method of the rare scandium monocyclopentadienyl catalyst system in this comparative example is prepared by referring to the relevant method described in Yang Ke. Research on the polymerization reaction of isobutylene initiated by scandium monocyclopentadienyl [D]. Dalian University of Technology, 2019.

[0113] The preparation method of polyisobutylene in this comparative example comprises the following steps: using 10 μmol of scandium monocyclopentadienyl, B / Ti=2:1, using 60 ml of toluene as solvent, and 100 g of isobutylene, reacting at 40° C. for 1 h, separating unreacted monomers after the reaction, releasing the reaction product, washing with acid, alkali, and water in sequence until neutral, obtaining a colorless and transparent intermediate product, removing the solvent and oligomers by reduced pressure distillation, and finally obtaining 47 g of a polyisobutylene product;

[0114] The GPC analysis results of the polyisobutylene product prepared in this comparative example are shown in the attached Figure 4 As shown in (k), through Figure 4 (k) It can be seen that the product Mn is 6765 and the molecular weight distribution is 4.23.

[0115] Comparative Example 5

[0116] The difference from Comparative Example 4 is that the solvent is replaced by hexane from toluene. Finally, 57 g of polyisobutylene product is obtained;

[0117] The GPC analysis results of the polyisobutylene product prepared in this comparative example are shown in the attached Figure 4 As shown in (l), through Figure 4 (l) It can be seen that the product Mn is 5449 and the molecular weight distribution is 2.07.

[0118] Comparative Example 6

[0119] The difference from Comparative Example 4 is that the amount of monotantalum is increased to 50 μmol. Finally, 58 g of polyisobutylene product is obtained.

[0120] The GPC analysis results of the polyisobutylene product prepared in this comparative example are shown in the attached Figure 4 (m) as shown, through Figure 4 (m) It can be seen that the product Mn is 3484 and the molecular weight distribution is 3.29.

[0121] Combined with Figures 1 to 4 According to the above-mentioned Examples 1 to 8 and Comparative Examples 1 to 6, the metallocene catalyst system provided by the present invention can catalyze the polymerization of isobutylene under mild conditions at 40°C to obtain a medium molecular weight polyisobutylene product, which has the characteristics of high molecular weight and narrow molecular weight distribution, and the catalyst activity is as high as 7.5×10 6 g isobutylene / mol Cat·h -1The above-mentioned reason for the excellent performance of the catalyst system is that the electron donor additive stabilizes the active center of the metallocene catalyst, which inhibits the chain transfer and isomerization side reactions and improves the catalyst activity. The use of the same catalyst system to catalyze the polymerization of isobutylene follows the traditional cationic polymerization reaction rules. Under high temperature conditions, the cationic active center is extremely active, and chain transfer and isomerization side reactions are prone to occur. Therefore, under the same conditions, the product obtained has a low molecular weight, a narrow distribution, and a low catalyst activity.

[0122] The inventors used [2-(2,3,4,5-tetramethylcyclopentadienyl)-4-tert-butyl-6-tritylphenoxy]titanium dichloride as component A, kept B / A, C / A, D / A and other reaction conditions the same as in Example 1, and used different components B, C, and D for comparative tests to further optimize the best combination catalyst system, and further made Examples 9 to 16.

[0123] The catalyst materials and product data results used in Examples 9 to 16 are shown in Table 2 below.

[0124] Table 2 Catalyst materials and product data results of Examples 9 to 16

[0125]

[0126]

[0127] From the evaluation results of the above catalyst system, it can be seen that the product obtained by catalyzing the polymerization of isobutylene using the [2-(2,3,4,5-tetramethylcyclopentadienyl)-4-tert-butyl-6-tritylphenoxy] titanium dichloride / Ph3CB(C6F5)4 / triisobutylaluminum / MTBE combined catalyst system in Example 1 has a higher molecular weight, a narrower molecular weight distribution and a higher catalytic activity. Therefore, this combined catalyst system is preferred for further investigation of process conditions.

[0128] Using the above preferred catalyst system and fixing the amount of isobutylene at 100 g, the inventors made Examples 17 to 38 by changing the molar ratios of the components in the catalyst and the polymerization reaction conditions. The specific condition parameters and product data results are shown in Table 3 below.

[0129] Table 3 Condition parameters and product data results of Examples 17 to 38

[0130]

[0131]

[0132] From the analysis of the product data results in Table 3, it can be seen that by adjusting the reaction temperature, reaction time, and the dosage and ratio of each component of the catalyst, the molecular weight of the product can be flexibly controlled in the range of 0 to 80 °C, and the molecular weight distribution of the product can be stabilized within 2.2. At the same time, the catalyst can maintain a high catalytic activity (3×10 4 ~8×10 6 mol isobutylene / molCat·h -1 ).

[0133] Based on the above embodiments and comparative test analysis data, it can be seen that the technical solution is feasible and has certain advancement.

[0134] The above are only preferred feasible embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Various modifications or applications made according to the above embodiments are within the protection scope of this technical solution.

[0135] Although the specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art. According to all the teachings disclosed, various modifications and replacements can be made to those details, and these changes are all within the protection scope of the present invention. The full scope of the present invention is given by the attached claims and any equivalents thereof.

Claims

1. A metallocene catalyst system, characterized in that The catalyst system comprises four components A, B, C and D; the component A is a metallocene complex; the component B is a borate; the component C is an alkyl aluminum; and the component D is selected from alkyl ethers with 2 to 8 carbon atoms.

2. The metallocene catalyst system according to claim 1, characterized in that The component A is a bridged or non-bridged metallocene complex; The general structural formula (I) of the bridging component A is Cp' n (X')MX m ; The structural formula (II) of the non-bridging component A is Cp' n MX m ; In formula (I) and (II), Cp' is selected from substituted or unsubstituted cyclopentadienyl, indenyl, fluorenyl; M is an active center metal; X is selected from halogen, alkyl, alkoxy, amino or acid radical; n is 1 or 2, and m is an integer satisfying the valence state of M.

3. The metallocene catalyst system according to claim 2, characterized in that In the Cp', the substituent is selected from one or more of an aryloxy group, a substituted aryloxy group, an alkyl group, an alkoxy group, and a silane group.

4. The metallocene catalyst system according to claim 3, characterized in that The substituted aryloxy group is selected from aryloxy groups substituted by alkyl groups having 1 to 18 carbon atoms.

5. The metallocene catalyst system according to claim 2, characterized in that The M is selected from one of Ti, Zr or Hf.

6. The metallocene catalyst system according to claim 2, characterized in that When component A is a bridged metallocene complex, X' is selected from one of SiR2, CR2, SiR2SiR2, CR2CR2, CR=CR or (CR3)2Si.

7. The metallocene catalyst system according to claim 6, characterized in that Said R is hydrogen; Or R is selected from an alkyl group, an aryl group, a silyl group, a halogenated alkyl group or a halogenated aryl group having less than 20 carbon atoms.

8. The metallocene catalyst system according to any one of claims 2 to 7, characterized in that: The component A is selected from one of Cp'TiX2, Cp'ZrX2, Cp'2ZrX2, Cp'2HfX2, and Cp'2(CR3)2SiZrX2.

9. The metallocene catalyst system according to claim 1, characterized in that The component B is selected from Ph3CB(C6F5)4, PhNMe2HB(C6F5)4, B(C6F5)3 or [(C a H 2a+1 )2NH(C b H2 b+1 )][B(C6F5)4], wherein 2≤a≤20, 1≤b≤20, and a and b are both integers.

10. The metallocene catalyst system according to claim 9, characterized in that The component B is selected from one of Ph3CB(C6F5)4, PhNMe2HB(C6F5)4 or B(C6F5)3.

11. The metallocene catalyst system according to claim 1, characterized in that The component C is trialkylaluminum; The trialkylaluminum is selected from one of trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, tri-n-decylaluminum and tri-n-dodecylaluminum.

12. The metallocene catalyst system according to claim 11, characterized in that The component C is selected from one of triethylaluminum, triisopropylaluminum, triisobutylaluminum, tri-n-hexylaluminum or tri-n-octylaluminum.

13. The metallocene catalyst system according to claim 1, characterized in that The component D is selected from one of methyl ether, isopropyl ether, n-butyl ether or methyl tert-butyl ether.

14. Use of the metallocene catalyst system according to any one of claims 1 to 13 in catalyzing the polymerization of isobutylene.

15. A method for preparing polyisobutylene, characterized in that: When preparing polyisobutylene, the method uses the metallocene catalyst system as described in any one of claims 1 to 12 to catalyze the polymerization of isobutylene.

16. The method for preparing polyisobutylene according to claim 15, characterized in that: The following steps are involved: S1. Refining of raw materials and solvents After sieving isobutylene and solvent, drying and dehydration are performed; S2, Aggregation Under dry and oxygen-free conditions, a solvent, isobutylene and component C are added in sequence, stirred and mixed, the temperature is increased, and components A, B and D are added to participate in polymerization to obtain a crude polymerization product; S3. Crude product pretreatment The crude polymer product obtained in S2 is acid-washed, and then alkali-washed and water-washed in sequence until the water washing liquid is neutral, and then allowed to stand for stratification, and the upper oil phase is taken; S4. Purification of polymer products The oil phase product is distilled under reduced pressure to obtain a polyisobutylene product.

17. The method for preparing polyisobutylene according to claim 16, characterized in that: In S1, the solvent is selected from one or more of C2-C12 straight-chain alkanes, C4-C12 isomeric alkanes, C3-C8 cycloalkanes, benzene or substituted benzenes.

18. The method for preparing polyisobutylene according to claim 16, characterized in that: In the S2, the polymerization temperature is 0-100°C, the time is 0.1-4h, and the pressure is 0-2MPa.

19. The method for preparing polyisobutylene according to claim 16, characterized in that: In S2, the molar ratio of the component A to the component B is 1:(0.5-3); the molar ratio of the component A to the component C is 1:(1-60); and the molar ratio of the component A to the component D is 1:(0.01-1).

20. The method for preparing polyisobutylene according to claim 19, characterized in that: The molar ratio of the component A to the component B is 1:(1-2.5); the molar ratio of the component A to the component C is 1:(2-40); and the molar ratio of the component A to the component D is 1:(0.05-1).

21. The method for preparing polyisobutylene according to claim 16, characterized in that: In S2, the mass ratio of the isobutylene to the solvent is (2-12):

1.

22. The method for preparing polyisobutylene according to claim 16, characterized in that: In S2, the molar ratio of isobutylene to component A is (1×10 4 ~1×10 7 ):

1.

23. The method for preparing polyisobutylene according to claim 22, characterized in that: The molar ratio of isobutylene to component A is (1×10 5 ~1×10 7 ):

1.

24. The method for preparing polyisobutylene according to claim 16, characterized in that: In S4, the pressure conditions of the reduced pressure distillation are -0.1 to -0.5 MPa and the temperature is 150 to 200°C.

25. A polyisobutylene, characterized in that: The polyisobutylene is prepared by the method according to any one of claims 15 to 24.

26. The polyisobutylene according to claim 25, characterized in that The number average molecular weight of the polyisobutylene is 5000-100000 and the molecular weight distribution is 1-2.

5.

27. The polyisobutylene according to claim 26, characterized in that The number average molecular weight of the polyisobutylene is 10,000 to 70,000, and the molecular weight distribution is 1 to 2.2.

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