Metallocene catalyst systems and uses thereof

Abstract

The invention provides a metallocene catalyst system and application thereof, and belongs to the field of olefin polymerization catalysts. The metallocene catalyst system comprises a main catalyst and a co-catalyst, the main catalyst has a structure as shown in a formula I: in the formula I, R1, R2, R3 and R4 are respectively and independently selected from substituted or unsubstituted alkyl and substituted or unsubstituted aryl; r5 and R6 are respectively and independently selected from substituted or unsubstituted alkyl and substituted or unsubstituted aryl; r7 and R8 are respectively and independently selected from halogen, nitryl, ester group, amino group, hydrogen and substituted or unsubstituted alkane; m is independently selected from zirconium, titanium or hafnium. The metallocene catalyst system provided by the invention has the characteristics of high catalytic activity, good copolymerization performance, excellent stability at high temperature, high copolymer molecular weight and excellent alpha-olefin universality, can be used for high-temperature copolymerization reaction of olefin, and is suitable for large-scale industrial production.

Description

Technical Field

[0001] This invention belongs to the field of olefin polymerization catalysts, specifically relating to a metallocene catalyst system and its application. Background Technology

[0002] Polyolefin materials are an important class of synthetic materials, possessing advantages such as light weight, high chemical stability, good electrical insulation, and good machinability, and are therefore widely used in various fields of daily life and industrial production. With the increasing application of polyolefin materials, the corresponding consumption and demand are also increasing year by year. The catalysts used in industrial production are gradually shifting from multiphase, multi-active-center Ziegler-Natta catalysts to single-active-center metallocene catalysts.

[0003] Compared with Zn catalysts, metallocene catalysts have a single active center, ultra-high catalytic activity, and produce polymers with narrower molecular weight distribution and excellent mechanical properties. They also have good copolymerization properties, such as the ability to efficiently catalyze the copolymerization of ethylene and α-olefins.

[0004] Researchers have discovered that by introducing different substituents, metallocene catalysts can acquire suitable steric and electronic effects. However, how to utilize different substituents to adjust the catalyst ligand structure, thereby altering the chelation environment and further changing the chelation tension to enhance polymerization activity and other catalytic effects, has been a key technical challenge for researchers. Summary of the Invention

[0005] The purpose of this invention is to provide a metallocene catalyst, its preparation method, and its application. This metallocene catalyst has the characteristics of high catalytic activity, good copolymerization performance, excellent stability at high temperature, high molecular weight of copolymer, and excellent α-olefin universality.

[0006] This invention proposes a metallocene catalyst system, comprising a main catalyst and a co-catalyst; the main catalyst has a structure as shown in Formula I:

[0007] Formula I, Among them, R 1 R 2 R 3 R 4 Each is independently selected from substituted or unsubstituted alkyl groups and substituted or unsubstituted aryl groups; R 5 and R 6 Each is independently selected from substituted or unsubstituted alkyl groups and substituted or unsubstituted aryl groups; R 7 and R 8 Each is independently selected from halogenated, nitro, ester, amino, hydrogen, substituted or unsubstituted alkanes; M is independently selected from zirconium, titanium, or hafnium.

[0008] Furthermore, R 1 R 2 R 3 R 4 Each of the following is independently selected from hydrogen, tert-butyl, phenyl, 4-fluorophenyl, 2,6-diisopropylphenyl, methyl, and 4-methoxyphenyl; Preferred, R 2 R 3 Each is independently selected from methyl groups.

[0009] Furthermore, the co-catalyst includes at least one of organoaluminum co-catalyst and boron co-catalyst.

[0010] Furthermore, the molar ratio of the main catalyst, organoaluminum co-catalyst, and boron co-catalyst is 1:50~300:0.8~5.

[0011] Furthermore, the organoaluminum cocatalyst is at least one of alkylaluminum compounds and aluminoxane compounds; More preferably, the organoaluminum cocatalyst includes at least one of methylaluminoxane, trimethylaluminum, triethylaluminum, and triisobutylaluminum.

[0012] Furthermore, the main catalyst is prepared by the following steps: S1. 2,7-Di-tert-butylfluorene is reacted with n-butyllithium to obtain lithium 2,7-di-tert-butylfluorene; S2, Add R to lithium 2,7-di-tert-butylfluorene 5 R 6 The reaction with SiCl2 yields a compound having the structure shown in Formula II; S3. Methylcyclopentadiene is reacted with n-butyllithium to obtain a compound having the structure shown in Formula III; S4. React the compound having the structure shown in Formula II with the compound having the structure shown in Formula III to obtain the compound having the structure shown in Formula IV. S5. React the compound having the structure shown in Formula IV with n-butyllithium to obtain the compound having the structure shown in Formula V. S6. React a compound having the structure shown in Formula V with a metal halide to obtain a metallocene catalyst having the structure shown in Formula VI. Formula II; Formula III; Formula IV; Formula V; Formula VI.

[0013] Furthermore, at least one of the following conditions must be met: (1) In S1, the molar ratio of 2,7-di-tert-butylfluorene to n-butyllithium is 1:1-1.5; (2) In S2, lithium 2,7-di-tert-butylfluorene reacts with R 5 R 6 The molar ratio of SiCl2 is 1:1-1.5; (3) In S3, the molar ratio of methylcyclopentadiene to n-butyllithium is 1:1-1.5; (4) In S4, the molar ratio of the compound having the structure shown in Formula II to the compound having the structure shown in Formula III is 1:1.1-1.5; (5) In S5, the molar ratio of the compound having the structure shown in Formula IV to n-butyllithium is 1:2~2.5; (6) In S6, the molar ratio of the compound having the structure shown in Formula V to the metal halide is 1:1~1.5; (7) In S6, the metal halide is HfCl4, ZrCl4 or TiCl4.

[0014] The present invention also proposes the application of any of the above-described metallocene catalyst systems in olefin copolymerization reactions.

[0015] Furthermore, the temperature for the olefin copolymerization reaction is 130℃-200℃; Preferably, the concentration of the main catalyst in the metallocene catalyst system is 1~10 μmol / mL.

[0016] Furthermore, the raw materials for the olefin copolymerization reaction include two or more of the following: ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, α-methylstyrene, or divinylbenzene. Preferably, the olefin copolymerization reaction is a copolymerization reaction of ethylene with at least one of propylene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, and 1-hexadecene.

[0017] This invention has the following advantages: The main catalyst in the metallocene catalyst system provided by this invention is a silicon-bridged bismetallocene catalyst. The increase in substituents on the fluorene and cyclopentadiene groups increases the steric hindrance of the catalyst, and the electron-donating groups on the bridging atoms enhance the electronic effect of the catalyst, further improving its activity in olefin polymerization reactions (e.g., ethylene / 1-octene copolymerization). The change in steric hindrance on the fluorene side makes the coordination space of the central atom more compact, resulting in a relatively higher molecular weight of the polymerization product. The metallocene catalyst system proposed in this invention features high catalytic activity, good copolymerization performance, excellent high-temperature stability, high copolymer molecular weight, and excellent α-olefin universality. It can be used for high-temperature copolymerization reactions of olefins and is suitable for large-scale industrial production. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 The above is the 1H NMR spectrum of the main catalyst obtained in Example 1 of this invention; Figure 2 The above is the 1H NMR spectrum of the main catalyst obtained in Example 2 of this invention; Figure 3 This is the 1H NMR spectrum of the main catalyst obtained in Example 3 of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0021] On one hand, one embodiment of the present invention provides a metallocene catalyst system, comprising a main catalyst and a co-catalyst; the main catalyst has a structure as shown in Formula I: Formula I, Among them, R 1 R 2 R 3 R 4 Each is independently selected from substituted or unsubstituted alkyl groups and substituted or unsubstituted aryl groups; R 5 and R 6Each is independently selected from substituted or unsubstituted alkyl groups and substituted or unsubstituted aryl groups; R 7 and R 8 Each is independently selected from halogenated, nitro, ester, amino, hydrogen, substituted or unsubstituted alkanes; M is independently selected from zirconium (Zr), titanium (Ti), or hafnium (Hf).

[0022] In one embodiment of the present invention, R 1 R 2 R 3 R 4 Each of the following is independently selected from hydrogen, tert-butyl, phenyl, 4-fluorophenyl, 2,6-diisopropylphenyl, methyl, and 4-methoxyphenyl. Preferably, R... 2 R 3 Each is independently selected from methyl groups.

[0023] In one embodiment of the present invention, the co-catalyst includes at least one of an organoaluminum co-catalyst and a boron co-catalyst.

[0024] In one embodiment of the present invention, the molar ratio of the main catalyst, the organoaluminum co-catalyst, and the boron co-catalyst is 1:50~300:0.8~5.

[0025] In one embodiment of the present invention, the boron co-catalyst has the structure shown in Formula VII: Formula VII.

[0026] In one embodiment of the present invention, the organoaluminum cocatalyst is at least one selected from alkylaluminum compounds and aluminoxane compounds. More preferably, the organoaluminum cocatalyst includes at least one selected from methylaluminoxane (MAO), trimethylaluminum (AlMe3), triethylaluminum (AlEt3), and triisobutylaluminum (AliBu3).

[0027] In a preferred embodiment of the present invention, the main catalyst is prepared by comprising the following steps: S1. 2,7-Di-tert-butylfluorene is reacted with n-butyllithium to obtain lithium 2,7-di-tert-butylfluorene; S2, Add R to lithium 2,7-di-tert-butylfluorene 5 R 6 The reaction with SiCl2 yields a compound having the structure shown in Formula II; S3. Methylcyclopentadiene is reacted with n-butyllithium to obtain a compound having the structure shown in Formula III; S4. React the compound having the structure shown in Formula II with the compound having the structure shown in Formula III to obtain the compound having the structure shown in Formula IV. S5. React the compound having the structure shown in Formula IV with n-butyllithium to obtain the compound having the structure shown in Formula V. S6. React a compound having the structure shown in Formula V with a metal halide to obtain a metallocene catalyst having the structure shown in Formula VI. Formula II; Formula III; Formula IV; Formula V; Formula VI.

[0028] In one embodiment of the present invention, in S1, the molar ratio of 2,7-di-tert-butylfluorene to n-butyllithium is 1:1-1.5.

[0029] In S1, the reaction temperature is -78 to 0 ℃ and the reaction time is 10 to 15 hours.

[0030] In one embodiment of the present invention, in S2, lithium 2,7-di-tert-butylfluorene and R 5 R 6 The molar ratio of SiCl2 is 1:1-1.5.

[0031] In one embodiment of the present invention, in S2, the reaction temperature is -10 to 0 ℃ and the reaction time is 10 to 15 h.

[0032] In one embodiment of the present invention, in S3, the molar ratio of methylcyclopentadiene to n-butyllithium is 1:1-1.5.

[0033] In one embodiment of the present invention, in step S3, the reaction temperature is -78 to 0°C and the reaction time is 20 to 30 hours.

[0034] It should be noted that the ice-water bath is used to bring the reaction system to 0°C.

[0035] In one embodiment of the present invention, in S4, the molar ratio of the compound having the structure shown in Formula II to the compound having the structure shown in Formula III is 1:1.1-1.5.

[0036] In one embodiment of the present invention, in step S4, the reaction temperature is 20~50℃ and the reaction time is 5~15 h.

[0037] In one embodiment of the present invention, in S5, the molar ratio of the compound having the structure shown in Formula IV to n-butyllithium is 1:2 to 2.5.

[0038] In one embodiment of the present invention, in step S5, the reaction temperature is -78 to 0°C and the reaction time is 10 to 20 hours.

[0039] In one embodiment of the present invention, in S6, the molar ratio of the compound having the structure shown in Formula V to the metal halide is 1:1 to 1.5.

[0040] In one embodiment of the present invention, in S6, the metal halide (halide of M) is HfCl4, ZrCl4 or TiCl4.

[0041] In one embodiment of the present invention, in step S6, the reaction temperature is -20 to 0°C and the reaction time is 12 hours.

[0042] In one embodiment of the present invention, in S1-S6, the reactions are all carried out under a protective gas atmosphere, the protective gas including nitrogen, helium or argon.

[0043] In one embodiment of the present invention, in steps S1-S6, the solvent used in the reaction includes at least one of aromatic solvents, ether solvents, and alkane solvents. Preferably, the solvent used in the reaction includes at least one of toluene, tetrahydrofuran, diethyl ether, and n-hexane.

[0044] In another aspect, an embodiment of the present invention also proposes a method for preparing the above-mentioned metallocene catalyst system, wherein the main catalyst and the co-catalyst are directly stirred and mixed evenly in the reaction system according to the needs of the polymerization reaction.

[0045] In another aspect, an embodiment of the present invention also proposes the application of the above-mentioned metallocene catalyst system in olefin copolymerization reaction.

[0046] In one embodiment of the present invention, in the olefin copolymerization reaction, the concentration of the main catalyst in the metallocene catalyst system is 1~10 μmol / mL.

[0047] In one embodiment of the present invention, the metallocene catalyst system includes a main catalyst and a co-catalyst, as well as reactants, reaction solvents, etc.

[0048] In one embodiment of the present invention, the temperature of the olefin copolymerization reaction is 130℃-200℃.

[0049] In one embodiment of the present invention, the raw materials for the olefin copolymerization reaction include two or more of the following: ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, α-methylstyrene, or divinylbenzene.

[0050] In one embodiment of the present invention, the reaction solvent for the olefin copolymerization reaction includes n-hexane, cyclohexane, heptane, decane, etc.

[0051] In one embodiment of the present invention, the olefin copolymerization reaction is a copolymerization reaction of ethylene with at least one of propylene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, and 1-hexadecene.

[0052] The present invention will now be described in detail with reference to the embodiments.

[0053] Example 1 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0054] Step 1: Under nitrogen protection, 50 mL of diethyl ether was added to a 100 mL round-bottom flask, which was then placed in an ice-water bath and stirred for 15 min. 5 g of 2,7-di-tert-butylfluorene (17.95 mmol) was weighed and added to the round-bottom flask, yielding a colorless and transparent solution. The solution was stirred for 15 min, and then n-butyllithium (9 mL, 2.4 M) was gradually added dropwise to the above system. After the reaction was completed by stirring for 12 h, the diethyl ether was removed under reduced pressure to obtain a yellow solid crude product, namely 4.71 g of 2,7-di-tert-butylfluorene monolithium salt, with a yield of 94.2%.

[0055] Step 2: Under nitrogen protection, weigh (2.50 g, 9.87 mmol) diphenyldichlorosilane into a 100 mL round-bottom flask, add 30 mL of diethyl ether and place in an ice-water bath. Add dropwise 30 mL of diethyl ether solution containing (8.29 g, 29.15 mmol) 2,7-di-tert-butylfluorene lithium salt, and react for 12 h. Filter out lithium chloride and dry under reduced pressure, precipitating 9.56 g of a pale yellow solid powder, denoted as 1a.

[0056] Step 3: Under nitrogen protection, 100 mL of diethyl ether was added to a dry 250 mL three-necked flask, which was then placed in an ice-water bath. Methylcyclopentadiene (10 g, 0.125 mol) was added to the three-necked flask, and n-butyllithium (55 mL, 2.4 M) was gradually added dropwise to the above reaction system. The mixture was stirred for 24 h. After the reaction was completed, the solvent was removed by vacuum to obtain 9.70 g of white powder, which was designated as 1b.

[0057] Step 4: Under nitrogen protection and in an ice-water bath, dissolve 1a (6.00 g, 20.31 mmol) and 1b (2.56 g, 30.45 mmol) in 30 mL of THF respectively. After thorough stirring, slowly add 1b dropwise to 1a. Then heat the reaction system to 50 °C and react for 12 h. After the reaction is complete, filter and remove the solvent to obtain 5.56 g of orange-red oily substance, which is denoted as 1c.

[0058] Step 5: Under nitrogen protection, 1c (5.56 g, 10.59 mmol) was placed in a 100 mL round-bottom flask, and 30 mL of toluene was added. The above system was placed in an ice-water bath, and then n-butyllithium (9.5 mL, 2.4 M) was gradually added dropwise to the reaction system. After stirring for 12 h, the solvent was removed under reduced pressure to obtain 4.45 g of yellow solid powder, which was recorded as 1d.

[0059] Step 6: Under nitrogen protection, 1d (4.45 g, 8.42 mmol) was placed in a 100 mL round-bottom flask, and 30 mL of toluene was added. The above system was placed in an ice-water bath, and ZrCl4 (2.06 g, 8.84 mmol) was gradually added dropwise to the above system. After stirring for 12 h, the reaction was completed. After filtration, the solvent was dried under reduced pressure to obtain 3.54 g of yellow solid powder, which is the metallocene catalyst.

[0060] The NMR results are as follows (see Figure 1 ): 1 H NMR (400 MHz, Chloroform-d): δ 8.13 (p, J = 3.4 Hz, 7H), 7.56 (h,J = 6.5 Hz, 10H), 7.01 (td, J = 7.8, 3.4 Hz, 2H), 6.90 – 6.81 (m, 2H), 6.31(t, J = 2.4 Hz, 1H), 5.83 (t, J = 2.8 Hz, 1H), 5.54 (t, J = 2.4 Hz, 1H), 3.48(q, J = 7.0 Hz, 1H), 2.20 (s, 3H).1.11 (s, 18H). Application Example 1 Olefin polymerization method using metallocene catalysts The olefin polymerization was carried out using the main catalyst obtained in Example 1, specifically including the following steps: (1) The copolymerization reaction of ethylene with α-olefins (specific types of α-olefins are listed in Table 3 or Table 4) is carried out in a high-pressure reactor with a capacity of 100 mL. The temperature, pressure and rotation speed can be adjusted. Before the reaction, the reactor is preheated under vacuum. After reaching the set temperature of 150°C, the reactor is flushed three times with nitrogen gas.

[0061] (2) Dissolve the above main catalyst in toluene solvent to prepare a main catalyst solution with a concentration of 2 μmol / mL. Then, add 17.8 mL of n-hexane dehydrated and deoxygenated by sodium metal reflux, 7.1 mL of 1-octene dried by calcium hydride reflux (see Table 3 or Table 4, the concentrations listed are 1.5 M, 2.0 M or 2.5 M), 2 mL of toluene solution of boron co-catalyst shown in Formula VII with a concentration of 1.1 μmol / mL, 2 mL of triisobutylaluminum solution of organoaluminum co-catalyst with a concentration of 100 μmol / mL, and 1 mL of main catalyst solution with a concentration of 2 μmol / mL to the feeding hopper. Finally, rinse with the remaining solvent and flush the remaining catalyst in the feeding hopper into the feeder. Close the feeder valve and flush the solution in the feeder into the reactor with nitrogen. Open the valve to increase the pressure of the ethylene cylinder to the set value, turn on the stirrer and start timing, and control the temperature at around the set value (see Table 3 or Table 4, the reaction temperature is 120℃, 140℃ or 150℃).

[0062] (3) After the reaction is complete, close the ethylene inlet valve, turn on the cooling water to cool down, open the reactor, remove the liner, pour the product into a beaker, and add hydrochloric acid-ethanol solution to terminate the reaction. Rinse the polymer repeatedly with hydrochloric acid / ethanol solution to dissolve the aluminum salt remaining from the reaction, then wash it three more times with deionized water, and finally put it into a vacuum drying oven to dry to constant weight at 120°C, and calculate the catalytic activity of the catalyst.

[0063] The reaction raw materials, reaction operating conditions, polymer characteristics, and activity are listed in Tables 3-7.

[0064] Example 2 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0065] The preparation method is the same as in Example 1, except that diphenyldichlorosilane in Example 1 is replaced with dimethyldichlorosilane.

[0066] The NMR results are as follows (see Figure 2 ): 1H NMR (400MHz Chloroform-d): δ 8.04-7.94 (m,2H), 7.69 (ddq, J = 11.5, 4.4, 2.6, 2.1 Hz, 3H), 7.44 (s, 1H), 7.37 (s,1H), 6.22 (t, J = 25 Hz, 1H), 5.59 (t, J = 28 Hz, 1H), 5.30 (d, J = 29 Hz, 1H).2.06 (s, 3H), 1.34 (d, J = 3.6Hz, 25H) Application Example 2 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Example 2 is used instead of the main catalyst obtained in Example 1.

[0067] Example 3 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0068] The preparation method is the same as in Example 1, except that the methylcyclopentadienyl lithium in Example 1 is replaced with isopropylcyclopentadienyl lithium.

[0069] The NMR results are as follows (see Figure 3 ): 1 H NMR (400 MHz, Chloroform-d): δ 8.20-8.15 (m4H), 7.98 (dd, J = 8.7, 2.1, Hz 2H), 7.65-7.54 (m, 9H), 6.72 (dd, J = 13.7,1.6Hz, 2H), 6.41 (t, J = 25Hz, 1H), 5.81 (J = 28Hz, 1H), 5.52 (t, J = 24Hz, 1H), 1.08 (d, J = 7.0Hz, 5H), 1.00 (s, 19H). Application Example 3 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Example 3 is used instead of the main catalyst obtained in Example 1.

[0070] Example 4 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0071] The preparation method is the same as in Example 1, except that ZrCl4 in Example 1 is replaced with HfCl4.

[0072] Application Example 4 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Example 4 is used instead of the main catalyst obtained in Example 1.

[0073] Example 5 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0074] The preparation method is the same as in Example 2, except that ZrCl4 in Example 2 is replaced with HfCl4.

[0075] Application Example 5 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Example 5 is used instead of the main catalyst obtained in Example 1.

[0076] Example 6 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0077] The preparation method is the same as in Example 3, except that ZrCl4 in Example 23 is replaced with HfCl4.

[0078] Application Example 6 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Example 6 is used instead of the main catalyst obtained in Example 1.

[0079] Example 7 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0080] The preparation method is the same as in Example 1, except that methylcyclopentadiene is replaced with isopropylcyclopentadiene.

[0081] Application Example 7 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Example 7 is used instead of the main catalyst obtained in Example 1.

[0082] Example 8 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0083] The preparation method is the same as in Example 1, except that methylcyclopentadiene is replaced with tert-butylcyclopentadiene.

[0084] Application Example 8 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Example 8 is used instead of the main catalyst obtained in Example 1.

[0085] Example 9 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0086] The preparation method is the same as in Example 1, except that methylcyclopentadiene is replaced with isopropylcyclopentadiene and ZrCl4 is replaced with HfCl4.

[0087] Application Example 9 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Example 9 is used instead of the main catalyst obtained in Example 1.

[0088] Example 10 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0089] The preparation method is the same as in Example 1, except that methylcyclopentadiene is replaced with tert-butylcyclopentadiene and ZrCl4 is replaced with HfCl4.

[0090] Application Example 10 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Example 10 is used instead of the main catalyst obtained in Example 1.

[0091] Comparative Example 1 A method for preparing a metallocene catalyst The preparation method of the main catalyst (structure shown below) is the same as that described in US Patent US20050148460A1: Formula a.

[0092] Comparative Application Example 1 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Comparative Example 1 is used instead of the main catalyst obtained in Example 1.

[0093] The reaction raw materials, reaction operating conditions, polymer characteristics, and activity are listed in Tables 1 and 2.

[0094] Comparative Example 2 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0095] The preparation method is the same as in Example 1, except that methylcyclopentadiene is replaced with 3-tert-butylcyclopentadiene and 2,7-di-tert-butylfluorene is replaced with 2,7-diphenylfluorene.

[0096] Comparative Application Example 2 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Comparative Example 2 is used instead of the main catalyst obtained in Example 1.

[0097] The reaction raw materials, reaction operating conditions, polymer characteristics, and activity are listed in Tables 1 and 2.

[0098] Comparative Example 3 A method for preparing a metallocene catalyst Preparation of the main catalyst (structure shown below):

[0099] The preparation method is the same as in Example 1, except that methylcyclopentadiene is replaced with cyclopentadiene and 2,7-di-tert-butylfluorene is replaced with fluorene.

[0100] Comparative Application Example 3 Olefin polymerization method using metallocene catalysts The method is the same as in Application Example 1, except that the main catalyst obtained in Comparative Example 3 is used instead of the main catalyst obtained in Example 1.

[0101] The reaction raw materials, reaction operating conditions, polymer characteristics, and activity are listed in Tables 1 and 2.

[0102] Table 1. Polymerization conditions and polymerization data of ethylene / 1-octene in comparative catalysis

[0103] Table 2 Comparative Examples and Polymerization Conditions and Data for Different α-olefins

[0104] Table 3. Polymerization conditions and polymerization data of ethylene / 1-octene catalyzed in the examples.

[0105] Table 4 Examples and Polymerization Conditions and Data for Different α-Olefins

[0106] Table 5. Polymerization conditions and polymerization data of ethylene / propylene in the examples.

[0107] Table 6. Distribution of C NMR sequences of some polymers under different reaction conditions

[0108] Table 7 Uniaxial tensile properties of ethylene / 1-octene copolymers under different reaction conditions

[0109] Other reaction conditions for olefin polymerization in Examples 1-3 above: metallocene catalyst dosage 2 µmol, Al:M:B = 100:1:1.1, reaction time 10 min.

[0110] A comparison of the experimental data of the comparative examples in Tables 1 and 2 with the experimental data of the embodiments in Tables 3, 4, and 5 shows that, under the same reaction conditions, the metallocene catalysts of Examples 1-3 of the present invention exhibit higher catalytic activity compared to Comparative Example 1; and can maintain high polymerization activity at high temperatures, indicating that Examples 1-3 have high thermal stability; and the polymerization products generally have higher molecular weights. A comparison of the structure of the catalyst in Comparative Example 1 with the structures of the embodiments reveals that when the catalyst in Comparative Example 1 contains tert-butyl groups on both sides of the fluorene group and a benzene ring substituent on one side, the overall steric hindrance of the catalyst increases, thus reducing the activity of the comparative example catalyst. In contrast, the catalyst structures of Examples 1-3 contain alkyl substituents on the cyclopentadiene and only tert-butyl substituents on the fluorene group side, resulting in lower overall steric hindrance and thus higher activity of the catalysts in the embodiments.

[0111] Further research by the inventors revealed that, for metallocene catalysts, the introduction of substituents onto the fluorene group and cyclopentadiene significantly enhances the coordination environment of the central atom, resulting in high molecular weight polymers. However, excessive steric hindrance also hinders the catalytic reaction (as shown in formula a). Specifically, DFT calculations showed that the embedding volume of the catalyst in formula a reached 80.7%. Excessive steric hindrance can negatively impact the insertion of long-chain α-olefins, reducing their activity and copolymerization performance. In contrast, the catalyst structure proposed in this invention, although lacking only one benzene ring on the fluorene group, exhibits significantly reduced steric hindrance. The steric hindrance of the catalyst in this invention is between 60.9% and 61.7%, allowing for greater insertion of long-chain α-olefins, resulting in higher catalyst activity and better copolymerization performance.

[0112] Meanwhile, a comparison of the experimental data of the comparative examples in Tables 1 and 2 with the experimental data of the embodiments in Tables 3, 4, and 5 shows that the metallocene catalysts of Examples 1-3 of the present invention also exhibit higher catalytic activity compared with Comparative Examples 2 and 3, and the overall molecular weight of the polymerization products is higher. A comparison of the structures of the comparative catalysts and the embodiments reveals that the catalyst in Comparative Example 2 has benzene ring substituents on both sides of the fluorene group, resulting in increased overall steric hindrance and thus reduced activity. Compared with the catalysts in the embodiments, Comparative Example 3 lacks alkyl substituents on the cyclopentadiene group, resulting in lower activity. The catalysts in Examples 1-3 have alkyl substituents on the cyclopentadiene group and tert-butyl substituents on the fluorene group side. The tert-butyl substituents have less steric hindrance than the phenyl substituents, resulting in higher activity for the catalysts in the embodiments.

[0113] Tables 4, 5, and 6 show that Examples 1-3 all exhibited high activity and high propylene or octene insertion rates in the copolymerization of ethylene and different α-olefins, indicating that Examples 1-3 possess high copolymerization performance. Table 7 shows that the polymers also exhibit strong tensile strength and high elongation at break, reaching a maximum of 1573%. The molecular weight (M...) of the polymers obtained in Examples 1-3... w The range varies depending on the reaction conditions. When the octene concentration is 1.5 M, the molecular weight of the polymer is relatively large, reaching a maximum of 24.99 × 10⁻⁶. 4 As the concentration of octene and the temperature increase, the molecular weight of the polymer decreases, resulting in polymers with different molecular weights. These properties endow the polymers with good mechanical properties, processing properties, low-temperature elasticity and lightweight characteristics, enabling them to be widely used in many fields and possessing high practical value and market prospects.

[0114] It should be noted that EEE is the ethylene-ethylene-ethylene triunit sequence; EEO is the ethylene-ethylene-1-octene triunit sequence; OEO is the 1-octene-ethylene-1-octene triunit sequence; EOE is the ethylene-1-octene-ethylene triunit sequence; OOE is the 1-octene-1-octene-ethylene triunit sequence; and OOO is the 1-octene-1-octene-1-octene triunit sequence.

[0115] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A metallocene catalyst system, characterized in that, It includes a main catalyst and a co-catalyst; the main catalyst has a structure as shown in Formula I: Equation I, Among them, R 1 R 2 R 3 R 4 Each is independently selected from substituted or unsubstituted alkyl groups and substituted or unsubstituted aryl groups; R 5 and R 6 Each is independently selected from substituted or unsubstituted alkyl groups and substituted or unsubstituted aryl groups; R 7 and R 8 Each is independently selected from halogenated, nitro, ester, amino, hydrogen, substituted or unsubstituted alkanes; M is independently selected from zirconium, titanium, or hafnium.

2. The metallocene catalyst system according to claim 1, characterized in that, R 1 R 2 R 3 R 4 Each of the following is independently selected from hydrogen, tert-butyl, phenyl, 4-fluorophenyl, 2,6-diisopropylphenyl, methyl, and 4-methoxyphenyl; Preferred, R 2 R 3 Each is independently selected from methyl groups.

3. The metallocene catalyst system according to claim 1, characterized in that, The co-catalyst includes at least one of organoaluminum co-catalyst and boron co-catalyst.

4. The metallocene catalyst system according to claim 3, characterized in that, The molar ratio of the main catalyst, organoaluminum co-catalyst, and boron co-catalyst is 1:50~300:0.8~5.

5. The metallocene catalyst system according to claim 3, characterized in that, The organoaluminum cocatalyst is at least one of alkylaluminum compounds and aluminoxane compounds; More preferably, the organoaluminum cocatalyst includes at least one of methylaluminoxane, trimethylaluminum, triethylaluminum, and triisobutylaluminum.

6. The metallocene catalyst system according to any one of claims 1 to 5, characterized in that, The main catalyst is prepared by the following steps: S1. 2,7-Di-tert-butylfluorene is reacted with n-butyllithium to obtain lithium 2,7-di-tert-butylfluorene; S2, Add R to lithium 2,7-di-tert-butylfluorene 5 R 6 The reaction with SiCl2 yields a compound having the structure shown in Formula II; S3. Methylcyclopentadiene is reacted with n-butyllithium to obtain a compound having the structure shown in Formula III; S4. React the compound having the structure shown in Formula II with the compound having the structure shown in Formula III to obtain the compound having the structure shown in Formula IV. S5. React the compound having the structure shown in Formula IV with n-butyllithium to obtain the compound having the structure shown in Formula V. S6. React a compound having the structure shown in Formula V with a metal halide to obtain a metallocene catalyst having the structure shown in Formula VI. Formula II; Formula III; Formula IV; Formula V; Formula VI.

7. The metallocene catalyst system according to claim 6, characterized in that, At least one of the following conditions must be met: (1) In S1, the molar ratio of 2,7-di-tert-butylfluorene to n-butyllithium is 1:1-1.5; (2) In S2, lithium 2,7-di-tert-butylfluorene reacts with R 5 R 6 The molar ratio of SiCl2 is 1:1-1.5; (3) In S3, the molar ratio of methylcyclopentadiene to n-butyllithium is 1:1-1.5; (4) In S4, the molar ratio of the compound having the structure shown in Formula II to the compound having the structure shown in Formula III is 1:1.1-1.5; (5) In S5, the molar ratio of the compound having the structure shown in Formula IV to n-butyllithium is 1:2~2.5; (6) In S6, the molar ratio of the compound having the structure shown in Formula V to the metal halide is 1:1~1.5; (7) In S6, the metal halide is HfCl4, ZrCl4 or TiCl4.

8. The application of the metallocene catalyst system according to any one of claims 1 to 7 in olefin copolymerization reaction.

9. The application according to claim 8, characterized in that, The temperature for the olefin copolymerization reaction is 130℃-200℃; Preferably, the concentration of the main catalyst in the metallocene catalyst system is 1~10 μmol / mL.

10. The application according to claim 8, characterized in that, The raw materials for the olefin copolymerization reaction include two or more of the following: ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-eicosene, dicyclopentadiene, 1,4-butadiene, 1,5-pentadiene, 1,6-hexadiene, styrene, α-methylstyrene, or divinylbenzene. Preferably, the olefin copolymerization reaction is a copolymerization reaction of ethylene with at least one of propylene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, and 1-hexadecene.

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