Group ivb metal complexes, methods for their preparation and use

Abstract

The application discloses a group IVB metal complex and a preparation method and application thereof. The metal complex has a structural expression as shown in the following formula. The group IVB metal complex disclosed by the application not only maintains high polymerization activity, but also obtains high molecular weight polyolefin elastomer in the application of catalyzing ethylene and alpha olefin copolymerization, and has an industrial application prospect.

Description

Technical Field

[0001] This invention relates to polyolefin catalysts, and more particularly to a class of group IVB metal complexes, their preparation methods, and applications. Background Technology

[0002] Polyolefin elastomers are a class of polyolefin materials copolymerized from ethylene and α-olefins such as 1-butene, 1-hexene, and 1-octene. Compared to traditional polyolefin plastics, polyolefin elastomers have a higher content of comonomers in their molecular chains and a lower density, combining the properties of both plastics and rubber. They are widely used in automotive plastic modification, shoe material foaming, photovoltaic films, wires and cables, and artificial turf.

[0003] Metal catalysts, as a core technology in the manufacturing process of polyolefin elastomers, largely determine various microscopic parameters of the polymer, such as molecular weight, comonomer insertion rate, molecular weight distribution, and the number and distribution of branches, directly influencing the polymer's mechanical, electrical, and optical properties. Since the 1990s, academia and industry have been continuously developing polyolefin catalysts with different structures and characteristics. Representative examples include Dow's CGC-type catalyst (EP0416815A2), Mitsui Chemicals' FI catalyst (Chem. Lett. 1999, 10, 1065), and Dow's tetraphenyloxy catalysts. With the continuous development of catalyst technology, the ability of catalysts to control polymer structure has become increasingly precise, resulting in higher catalyst activity and lower production costs. To further reduce the production cost of polyolefin elastomers, improving the high-temperature resistance of catalysts has become crucial. However, FI catalysts only withstand temperatures up to about 100℃, CGC catalysts only up to 160℃, and while tetraphenyloxy catalysts can maintain high catalytic activity at 180℃, the molecular weight of the polymer decreases significantly at high temperatures, making it impossible to balance high temperature resistance and high molecular weight. Therefore, developing catalysts with high activity and high polymer molecular weight under high temperature conditions has become an urgent problem to be solved. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a class of group IVB metal complexes, their preparation methods, and applications. This invention utilizes metal complexes with unique bridged ring structures as catalyst ligands, which effectively protect the metal center. This ensures that even at high polymerization temperatures, the polymer β-H remains difficult to remove, resulting in high activity and a high polymer molecular weight.

[0005] A class of group IVB metal complexes has the structural expression shown in Formula I:

[0006]

[0007] In Formula I, M is selected from group IVB metals;

[0008] R1, R2, R3, and R4 each independently include the following groups: hydrogen, halogen, C1-C 10 Alkyl, C6-C 30 Aromatic groups;

[0009] X is selected from halogens, C1-C8 alkyl groups, benzyl groups, and dimethylamino groups;

[0010] n is an integer from 0 to 5, preferably an integer from 1 to 3, and more preferably an integer from 1 to 2.

[0011] In a preferred embodiment of the present invention, M in Formula I is selected from Ti, Zr, or Hf.

[0012] In a preferred embodiment of the present invention, X in Formula I is selected from chloro, methyl, or benzyl.

[0013] As a preferred embodiment of the present invention, in Formula I, R1, R2, R3, and R4 each independently include the following groups: fluorine, methyl, ethyl, isopropyl, tert-butyl, and trifluoromethyl.

[0014] As a preferred embodiment of the present invention, the metal complex is selected from at least one of the following substances having the following structural formulas:

[0015]

[0016] The present invention also provides a method for preparing group IVB metal complexes as described above, characterized in that, in an ultra-dry organic solvent, a compound of formula II is complexed with a metal salt MX to obtain a complex of formula I.

[0017]

[0018] In Equation II, the definitions of R1, R2, R3, and R4, as well as the values ​​of n, are the same as those in the previous text.

[0019] In the MX, M represents a group IVB metal compound, and X represents any one of halogen, C1-C8 alkyl, benzyl, or dimethylamino, and the ratio of the two satisfies the valence equilibrium of the substance.

[0020] Preferably, the MX is selected from TiCl4, ZrCl4, or HfCl4.

[0021] Preferably, the ultra-dry organic solvent is one or more selected from tetrahydrofuran, diethyl ether, pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, methylcyclohexane, toluene, xylene, methyl tert-butyl ether, and ethylene glycol dimethyl ether.

[0022] Preferably, the molar ratio of compound II to MX is 1:(1-2), more preferably 1:(1-1.5), and even more preferably 1:(1-1.2);

[0023] Preferably, the complexation reaction temperature is -78°C to 100°C, more preferably -20°C to 60°C, and even more preferably 0-30°C; the reaction time is 1-24 hours, more preferably 5-20 hours, and even more preferably 10-15 hours.

[0024] In this invention, after the reaction is completed, post-processing and purification processes such as recrystallization and silica gel column chromatography are included. These are conventional operations in the field and are not specifically limited by this invention.

[0025] As a preferred embodiment of the present invention, the preparation method of compound II is as follows:

[0026]

[0027] 1) In an ultra-dry organic solvent, compound 1 and compound 2 are reacted under the action of an alkali to produce compound 3;

[0028] 2) In an ultra-dry organic solvent, compound 3 is reacted with an alkyllithium reagent to obtain a lithium salt, which is then reacted with compound 4 to obtain compound II.

[0029] As a preferred embodiment of the present invention, in step 1), the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, and sodium hydride;

[0030] Preferably, the molar ratio of compound 1, base, and compound 2 is 1:(1-5):(0.5-1);

[0031] Preferably, compound 1 is selected from one or more of 2-bromo-4-methylphenol, 2-bromo-4-tert-butylphenol, and 2-bromo-6-fluorophenol;

[0032] Preferably, compound 2 is selected from at least one of 1,3-dibromopropane, 1,4-dibromobutane, and 1,5-dibromopentane;

[0033] Preferably, in step 1), the reaction temperature is 30-100℃ and the reaction time is 4-12 hours.

[0034] As a preferred embodiment of the present invention, in step 2), the alkyl lithium reagent is one or more of methyl lithium, n-butyl lithium, n-hexyl lithium, and diisopropylamino lithium;

[0035] Preferably, the molar ratio of compound 3, alkyllithium reagent, and compound 4 is 1:(1-2):(2-3);

[0036] Preferably, compound 4 is 2,3-epoxypropylnorbornene;

[0037] Preferably, in step 2), the reaction temperature is -20°C to 40°C, and the reaction time is 2-12 hours.

[0038] The present invention also provides the application of the IVB group metal complex as described above or the IVB group metal complex prepared by the method described above in the polymerization of ethylene and α-olefins to prepare polyolefin elastomers.

[0039] Preferably, the α-olefin is one or more selected from 1-butene, 1-hexene, and 1-octene.

[0040] As a preferred embodiment of the present invention, the polymerization reaction is carried out in the presence of an aluminum-containing co-catalyst and a group IVB metal complex main catalyst.

[0041] Preferably, the aluminum-containing co-catalyst is one or more of methylaluminoxane, isobutyl-modified methylaluminoxane, or octyl-modified methylaluminoxane;

[0042] Preferably, the molar ratio Al / M of metallic aluminum in the aluminum-containing co-catalyst to metallic M in the main catalyst is (1-10000):1, more preferably (200-5000):1;

[0043] Preferably, the polymerization reaction temperature is 100-200℃, more preferably 120-190℃, and even more preferably 140-180℃, and the polymerization reaction pressure is 1-5MPa, more preferably 2-4MPa, and even more preferably 2-3MPa.

[0044] Preferably, the polymerization reaction is carried out in an organic solvent selected from one or more of Isopar E, toluene, n-hexane, and cyclohexane.

[0045] The IVB metal complex disclosed in this invention, when used in the catalytic copolymerization of ethylene and α-olefins, not only maintains high polymerization activity under high polymer conditions, but also achieves high molecular weight polyolefin elasticity, showing promising prospects for industrial application. Detailed Implementation

[0046] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0047] Unless otherwise specified, all materials and reagents used in the following examples were obtained commercially, as detailed below:

[0048] n-Hexane: AR, Innochem

[0049] Potassium carbonate: AR, Innochem

[0050] n-Butyllithium: AR, Acros

[0051] ZrCl4: AR Yanfeng Technology

[0052] Tetrahydrofuran: AR, Innochem

[0053] Diethyl ether: AR, Innochem

[0054] Ethyl acetate: AR, Innochem

[0055] 2-Bromo-4-tert-butylphenol: AR, Leyan Reagent

[0056] 2-Bromo-4-methylphenol: AR, Aladdin

[0057] 2-Bromo-6-fluorophenol: AR, Myriel

[0058] Isopar E:AR, Exxon Mobil

[0059] MMAO-7 (Octoyl-modified methylaluminoxane): AR, Nouryon

[0060] 1,3-Dibromopropane: AR, Sigma-Aldrich

[0061] 1,4-Dibromobutane: AR, Sigma-Aldrich

[0062] 2,3-Epoxypropylnorbornene: AR, Aladdin

[0063] Unless otherwise specified, all other raw materials and reagents were obtained through commercially available channels.

[0064] The compounds in the following examples were characterized using a nuclear magnetic resonance spectrometer (Brucker ARX-400) and an elemental analyzer (FlashEA1112 microanalyzer).

[0065] The molecular weight and molecular weight distribution of the polymers obtained in the following ethylene polymerization examples were obtained by testing with a PL-GPC220 at 150°C using three PLgel 10μm MIXED-B separation columns in series, with 1,2,4-trichlorobenzene as the solvent.

[0066] In the examples, the ligands of the complexes were synthesized according to the following reaction route:

[0067]

[0068] Example 1:

[0069] Under a nitrogen atmosphere, in a 500 mL round-bottom flask, 18.7 g (0.1 mol) of 2-bromo-4-methylphenol was dissolved in 200 mL of tetrahydrofuran, followed by the addition of 27.6 g (0.2 mol) of potassium carbonate and then 10.1 g (0.05 mol) of 1,3-dibromopropane. The reaction was carried out at 60 °C for 8 hours, after which the reaction was stopped. The reaction solution was extracted three times with ethyl acetate, and the organic phases were combined and concentrated. After concentration to dryness, the product was separated by column chromatography using n-hexane / ethyl acetate (100:1, V / V). A total of 16.2 g of white solid product was finally obtained.

[0070] Product NMR characterization data: 1 H NMR(C6D6 400MHz)δ,2.12(s,6H),2.23(m,2H),4.29(m,4H),7.05(m,2H),7.26(m,2H),7.45(m,2H).

[0071] Under a nitrogen atmosphere, in a 500 mL round-bottom flask, 41.4 g (0.1 mol) of the above white solid product was dissolved in 200 mL of tetrahydrofuran. The reaction temperature was lowered to 0 °C, and then 55 mL of 2 mol / L (0.11 mol) n-butyllithium solution was slowly added dropwise. Then, 22.2 g (0.2 mol) of 2,3-epoxypropylnorbornene was added, and the reaction was continued at 0 °C for 5 hours. The reaction was then quenched by slowly adding 10 mL of water. The reaction solution was extracted three times with ethyl acetate, and the organic phases were combined and concentrated. After concentration to dryness, separation was performed by column chromatography using n-hexane / ethyl acetate (100:1, V / V). Finally, 42.2 g of white solid product, namely compound A of formula II, was obtained.

[0072] Product NMR characterization data: 1 H NMR(C6D6 400MHz)δ,1.35(m,4H),1.49(m,4H),1.78(m,2H),1.86(m,2H),2.04(m,2H),2.12(s,6H),2.18(m, 2H),2.23(m,2H),2.72(m,2H),3.76(brs,2H),4.35(m,4H),6.98(m,2H),7.27(m,2H),7.46(m,2H).

[0073] Under a nitrogen atmosphere, 9.52 g (0.02 mol) of compound A of formula II was dissolved in 40 ml of tetrahydrofuran in a 100 ml round-bottom flask. The reaction temperature was lowered to 0 °C, and then 4.6 g (0.02 mol) of ZrCl4 was added. After reacting for 10 hours, the reaction solution was filtered, the filter cake was collected, and recrystallized from toluene and n-hexane to obtain 8.1 g of white solid, denoted as metal complex A.

[0074] Example 2:

[0075] Under a nitrogen atmosphere, in a 500 mL round-bottom flask, 22.9 g (0.1 mol) of 2-bromo-4-tert-butylphenol was dissolved in 200 mL of tetrahydrofuran, followed by the addition of 69.0 g (0.5 mol) of potassium carbonate and then 10.1 g (0.05 mol) of 1,3-dibromopropane. The reaction was carried out at 60 °C for 9 hours, after which the reaction was stopped. The reaction solution was extracted three times with ethyl acetate, and the organic phases were combined and concentrated. After concentration to dryness, the product was separated by column chromatography using n-hexane / ethyl acetate (100:1, V / V). A final yield of 20.1 g of white solid product was obtained.

[0076] Product NMR characterization data: 1 H NMR(C6D6 400MHz)δ,1.35(s,18H),2.20(m,2H),4.25(m,4H),7.10(m,2H),7.45(m,2H),7.56(m,2H).

[0077] Under a nitrogen atmosphere, in a 500 mL round-bottom flask, 49.8 g (0.1 mol) of the above white solid product was dissolved in 200 mL of diethyl ether. The reaction temperature was lowered to 10 °C, and then 60.0 mL of 2 mol / L (0.12 mol) n-butyllithium solution was slowly added dropwise. Then, 26.5 g (0.025 mol) of 2,3-epoxypropylnorbornene was added, and the reaction was continued at 10 °C for 5 hours. The reaction was then quenched by slowly adding 10 mL of water. The reaction solution was extracted three times with ethyl acetate, and the organic phases were combined and concentrated. After concentration to dryness, separation was performed by column chromatography using n-hexane / ethyl acetate (100:1, V / V). Finally, 50.6 g of white solid product, compound B of formula II, was obtained.

[0078] Product NMR characterization data: 1 H NMR(C6D6 400MHz)δ,1.30(s,18H),1.31(m,4H),1.56(m,4H),1.84(m,2H),1.88(m,2H),2.04(m,2H),2.16(m, 2H),2.23(m,2H),2.68(m,2H),3.55(brs,2H),4.30(m,4H),6.87(m,2H),7.24(m,2H),7.36(m,2H).

[0079] Under a nitrogen atmosphere, in a 100 ml round-bottom flask, 11.2 g (0.02 mol) of compound B of formula II was dissolved in 40 ml of tetrahydrofuran. The reaction temperature was lowered to 5 °C, and then 4.2 g (0.022 mol) was added.

[0080] After reacting TiCl4 for 10 hours, the reaction solution was filtered, the filter cake was collected, and recrystallized with toluene and n-hexane to obtain 8.8 g of white solid, which was designated as metal complex B.

[0081] Example 3:

[0082] Under a nitrogen atmosphere, in a 500 mL round-bottom flask, 19.1 g (0.1 mol) of 2-bromo-6-fluorophenol was dissolved in 200 mL of diethyl ether, followed by the addition of 32.6 g (0.1 mol) of cesium carbonate and then 10.1 g (mol) of 1,3-dibromobutane. The reaction was carried out at 40 °C for 8 hours, after which the reaction was stopped. The reaction solution was extracted three times with ethyl acetate, and the organic phases were combined and concentrated. After concentration to dryness, the product was separated by column chromatography using n-hexane / ethyl acetate (200:1, V / V). A total of 17.2 g of white solid product was finally obtained.

[0083] Product NMR characterization data: 1 H NMR(C6D6 400MHz)δ,1.85(m,4H),4.12(m,4H),6.87(m,2H),7.10(m,2H),7.23(m,2H).

[0084] Under a nitrogen atmosphere, in a 500 mL round-bottom flask, 42.2 g (0.1 mol) of the above white solid product was dissolved in 200 mL of tetrahydrofuran. The reaction temperature was lowered to 5 °C, and then 75 mL of 2 mol / L (0.15 mol) n-butyllithium solution was slowly added dropwise. Then, 33.0 g (0.3 mol) of 2,3-epoxypropylnorbornene was added, and the reaction was continued at 10 °C for 6 hours. The reaction was then quenched by slowly adding 10 mL of water. The reaction solution was extracted three times with ethyl acetate, and the organic phases were combined and concentrated. After concentration to dryness, separation was performed by column chromatography using n-hexane / ethyl acetate (100:1, V / V). Finally, 45.2 g of white solid product, namely compound C of formula II, was obtained.

[0085] Product NMR characterization data: 1 H NMR(C6D6 400MHz)δ,1.35(m,4H),1.49(m,4H),1.78(m,2H),1.86(m,2H),1.90(m,4H),2.04(m,2H),2. 18(m,2H),2.72(m,2H),3.76(brs,2H),4.25(m,4H),6.98(m,2H),7.27(m,2H),7.46(m,2H).

[0086] Under a nitrogen atmosphere, in a 100 ml round-bottom flask, 9.7 g (0.02 mol) of compound C of formula II was dissolved in 40 ml of tetrahydrofuran. The reaction temperature was lowered to 10 °C, and then 7.68 g (0.024 mol) was added.

[0087] After reacting with HfCl4 for 10 hours, the reaction solution was filtered, the filter cake was collected, and recrystallized with toluene and n-hexane to obtain 7.5 g of white solid, which was denoted as metal complex C.

[0088] Comparative Example 1:

[0089] Catalyst X was prepared according to the method in Example 1.3 of WO2004044018A2.

[0090]

[0091] Referring to the different reaction conditions in Table 1, the metal complexes prepared in Examples 1-3 and Comparative Example 1 were applied to the catalytic polymerization reaction of ethylene and 1-octene, respectively, using the following methods:

[0092] A 0.5 μmol metal complex catalyst was encapsulated in an ampoule and pre-loaded into a 1 L high-pressure polymerization reactor. After drying at 120 °C for 1 h, the temperature was lowered to 100 °C, and 260 ml of n-hexane and 140 ml of 1-octene were added. Then, MMAO-7 was added according to the specific Al / M ratio. The reaction system temperature was raised to the set temperature, and ethylene was introduced, with the pressure set to 3 MPa. The ampoule was then broken, and the polymerization reaction began. The reaction pressure and temperature were maintained constant throughout the reaction. The reaction was stopped after 5 min. The ethylene in the reactor was replaced with nitrogen, and the temperature was lowered to 100 °C. The reaction solution was discharged through the bottom outlet into a beaker containing 500 ml of ethanol. After unloading, the solid polymer was filtered and dried.

[0093] Table 1. Reaction conditions and corresponding performance tests for different application examples.

[0094]

[0095]

[0096] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A class of group IVB metal complexes, characterized in that, It has the structure shown in Equation I: Equation I, In Formula I, M is selected from Ti, Zr, or Hf; R1, R2, R3, and R4 are each independently selected from the following groups: hydrogen, halogen, C1-C. 10 alkyl; X is selected from halogens, C1-C8 alkyl groups, benzyl groups, and dimethylamino groups; n is an integer between 0 and 5.

2. The group IVB metal complex according to claim 1, characterized in that, In Formula I, X is selected from chloro, methyl, or benzyl.

3. The group IVB metal complex according to claim 1 or 2, characterized in that, The metal complex is selected from at least one of the following substances having the following structural formulas: ， 。 4. A method for preparing a group IVB metal complex as described in any one of claims 1-3, characterized in that, In an ultra-dry organic solvent, the compound of formula II is complexed with the metal salt MX to obtain the complex of formula I; Formula II, In Formula II, the definitions of R1, R2, R3, and R4, as well as the value of n, are the same as in claim 1. In the MX, M is selected from Ti, Zr or Hf, and X represents any one of halogen, C1-C8 alkyl, benzyl or dimethylamino, and the ratio of the two satisfies the valence equilibrium of the substance.

5. The method for preparing group IVB metal complexes according to claim 4, characterized in that, The ultra-dry organic solvent is one or more selected from tetrahydrofuran, diethyl ether, pentane, cyclopentane, n-hexane, cyclohexane, n-heptane, methylcyclohexane, toluene, xylene, methyl tert-butyl ether, and ethylene glycol dimethyl ether.

6. The method for preparing group IVB metal complexes according to claim 4, characterized in that, The molar ratio of compound II to MX is 1:(1-2).

7. The method for preparing group IVB metal complexes according to claim 4, characterized in that, The complexation reaction temperature is -78℃ to 100℃, and the reaction time is 1-24h.

8. The method for preparing group IVB metal complexes according to claim 4, characterized in that, The preparation method of compound II is as follows: ， 1) In an ultra-dry organic solvent, compound 1 and compound 2 are reacted under the action of an alkali to produce compound 3; 2) In an ultra-dry organic solvent, compound 3 is reacted with an alkyllithium reagent to obtain a lithium salt, which is then reacted with compound 4 to obtain compound II.

9. The method for preparing group IVB metal complexes according to claim 8, characterized in that, In step 1), the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, and sodium hydride.

10. The method for preparing group IVB metal complexes according to claim 9, characterized in that, The molar ratio of compound 1, base, and compound 2 is 1:(1-5):(0.5-1).

11. The method for preparing group IVB metal complexes according to claim 9, characterized in that, In step 1), the reaction temperature is 30-100℃ and the reaction time is 4-12 hours.

12. The method for preparing group IVB metal complexes according to any one of claims 8-11, characterized in that, In step 2), the alkyl lithium reagent is one or more of methyl lithium, n-butyl lithium, n-hexyl lithium, and diisopropylamino lithium.

13. The method for preparing group IVB metal complexes according to claim 12, characterized in that, The molar ratio of compound 3, alkyllithium reagent, and compound 4 is 1:(1-2):(2-3).

14. The method for preparing group IVB metal complexes according to claim 12, characterized in that, In step 2), the reaction temperature is -20℃ to 40℃, and the reaction time is 2-12 hours.

15. The use of an IVB group metal complex as described in any one of claims 1-3 or an IVB group metal complex prepared by the method described in any one of claims 4-14 in the polymerization of ethylene and α-olefins to prepare polyolefin elastomers.

16. The application according to claim 15, characterized in that, The polymerization reaction was carried out in the presence of an aluminum-containing co-catalyst and a group IVB metal complex main catalyst.

17. The application according to claim 16, characterized in that, The aluminum-containing cocatalyst is one or more of methylaluminoxane, isobutyl-modified methylaluminoxane, or octyl-modified methylaluminoxane.

18. The application according to claim 16, characterized in that, The molar ratio of metallic aluminum to metallic M in the aluminum-containing co-catalyst, Al / M, is (1-10000):

1.

19. The application according to claim 18, characterized in that, The molar ratio Al / M of metallic aluminum in the aluminum-containing co-catalyst to metallic M in the main catalyst is (200-5000):

1.

20. The application according to claim 16, characterized in that, The polymerization reaction temperature is 100-200℃, and the polymerization reaction pressure is 1-5 MPa.

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