A polyolefin elastomer and its preparation method and used metallocene catalyst

Abstract

The application discloses a polyolefin elastomer and a preparation method thereof and a metallocene catalyst used in the preparation method, and the metallocene catalyst has the following formula I structure: wherein A is selected from N, S and P, M is a group IVB element, R1-R4 are the same or different and are selected from H and C1-C4 alkyl, R5 and R6 are the same or different and are selected from H and C1-C12 hydrocarbon groups. The metallocene catalyst with the specific structure is used to catalyze solution polymerization of propylene and alpha-olefin, the obtained copolymer has a melting point of 85-130 DEG C, the copolymer has a low-temperature (0 DEG C to -20 DEG C) impact strength of 5-20 KJ / m 2 2, and an elongation at break of 500%-1000%, so that the polyolefin elastomer with high toughness and good elongation at break can be obtained by the method.

Description

Technical Field

[0001] This invention relates to a polyolefin elastomer, its preparation method, and the metallocene catalyst used, belonging to the field of polymer synthesis technology. Background Technology

[0002] Elastomers have a long history of application due to their unique elastomeric properties, such as high tensile strength, high elongation at break, low-temperature resistance, crack growth resistance, and abrasion resistance. They are widely used in numerous fields, including household appliances, transportation, machinery, and the electronics industry. Furthermore, the types of elastomers have evolved from the earliest natural rubber to a variety of synthetic rubbers such as styrene-butadiene rubber (SBR) and butadiene rubber (BR). Compared to traditional rubber, thermoplastic elastomers exhibit rubber-like elasticity at room temperature and can be plasticized at high temperatures, allowing for repeated processing and reuse through extrusion and injection molding. Because thermoplastic elastomers possess a certain degree of crystallinity, they can achieve sufficient strength without cross-linking. Propylene-based elastomers, generally random copolymers of propylene and ethylene, offer advantages such as low cost, low density, and good chemical resistance. However, due to the internal crystalline structure of thermoplastic elastomers, their elongation at break is lower than that of traditional rubber. Therefore, improving the elongation at break of thermoplastic elastomers while maintaining their mechanical properties has significant practical application value. Elongation at break is a physical quantity that measures the flexibility of a sample, and it is usually related to the molecular weight, aggregation state, and phase structure of the polymer.

[0003] Polyolefin elastomers are a widely used class of polymer materials. They are copolymers of ethylene and propylene or other α-olefins (such as 1-butene, 1-hexene, 1-octene, etc.). These polyolefin materials can be used as films, wire and cable sheaths, resin toughening materials in automotive parts, and sealing strips, hoses, and tapes. The side methyl groups in the polypropylene molecular chain reduce the flexibility of the molecular chain, resulting in a high embrittlement temperature and poor impact resistance, especially high low-temperature brittleness, which limits its application range to some extent. To broaden the application range of polypropylene, toughening modification is usually performed on it.

[0004] Commonly used toughening modification methods include copolymerization modification, blending modification, addition of nucleating agents, and in-situ preparation of polypropylene in-reactor alloys. Toughening PP by copolymerizing α-olefins with propylene is one of the most common methods to improve the impact toughness of PP. The α-olefins refer to monoolefins with double bonds at the ends of the molecular chain, with the molecular formula R-CH=CH2, where R is H or an alkyl group with 2 or more carbon atoms. Commonly used α-olefins include ethylene, 1-butene, 1-hexene, and 1-octene. Compared with ethylene-propylene copolymers, propylene-1-butene random copolymers have higher rigidity at similar comonomer contents. Furthermore, using 1-butene instead of ethylene in copolymerization with propylene effectively reduces the amount of small-molecule atactic compounds in the polymer, thus avoiding the problem of excessive hexane extract in the product. Primarily used as a comonomer for polyethylene, propylene-1-hexene copolymers exhibit superior impact resistance, tensile strength, and tear strength compared to 1-butene copolymers.

[0005] The preparation processes of olefin copolymers include bulk polymerization, gas-phase polymerization, solution polymerization, and slurry polymerization. Solution polymerization is characterized by the use of a suitable solvent in which the (co)polymer formed by the polymerization reaction is continuously dissolved. In some cases, the solvent is the monomer itself, such as when polybutene is formed by polymerizing liquid butene-1. In other cases, the solvent is a hydrocarbon different from the monomer, such as in the preparation of ethylene propylene rubber (EPR or EPDM).

[0006] As early as the 1950s, metallocenes were studied as catalysts for olefin polymerization. Breslow and Natta independently used metallocenes as catalysts for olefin polymerization. This homogeneous catalyst was composed of Cp₂TiCl₂ / Et₂AlCl, with Ti as the active center. 4+ This system is easily over-reduced and loses its polymerization activity, resulting in low polymerization activity. Since the invention of the metallocene / methylaluminoxane system by Kaminsky et al. in the 1980s, metallocenes have seen rapid development, with hundreds or even thousands of metallocene compounds synthesized annually as catalysts for olefin polymerization. In recent years, advancements in structures ranging from unbridged to bridged, from bis-metallocenes to mono-metallocenes, from C-bridged to Si-bridged, from bridged bis-metallocenes to bridged heteroatoms, from various substituted metallocenes, functionalized metallocenes, and the design and synthesis of heteroatomic metallocenes containing B, N, P, and other elements have greatly promoted the synthesis, structure, and catalytic performance research of transition metal complexes, significantly enriching the chemistry of metallocene complexes. For many transition metal complex reactions, the heteroatom electronic effects of the ligands directly influence their stereoselectivity in olefin polymerization.

[0007] US Patent No. 5,767,209 describes a metallocene compound with a tetrahydrofuran group in its side chain, where the oxygen and sulfur atoms act as Lewis bases. Such metallocene compounds are easily loaded onto supports in large quantities and exhibit excellent reactivity in catalyzing olefin polymerization. CN1020101897 describes a class of metallocene catalysts with N and O atoms in their side chains, exhibiting high activity for olefin polymerization. US Patent No. 09 / 461,858 describes a large class of metallocene ligands in which the cyclopentadienyl group coordinated to the metal contains heteroatoms and various substituents. This metallocene, when combined with a co-catalyst, exhibits good activity in propylene polymerization. Similarly, CN102245620 describes a large class of metallocene complexes with substituents at the 5-position of the indenyl ring and optionally substituted furanyl or thiophene groups at the 2-position of the indenyl ring. These catalysts improve the absorption efficiency of ethylene or α-olefins and can yield high molecular weight rubber components, particularly ethylene / propylene copolymer components. In addition, propylene homopolymers with high melting points can be obtained. A similar metallocene catalyst containing S or O heterocycles is described in CN105985372A, which can copolymerize with long-chain α-olefins, but the copolymerization activity of long-chain α-olefins with ethylene is generally low, with a low insertion rate.

[0008] However, heteroatom-containing metallocene catalysts are still in their infancy and are rarely used in commercial production. Therefore, the impact of heteroatoms on the performance of metallocene catalysts is still under investigation and exploration. The special design of the molecular structure of metallocene compounds greatly alters the stereostructure and electronic effects. Whether this can significantly affect the copolymerization performance of olefins and stereoselectivity needs to be given greater attention in future research.

[0009] Patent CN201580019993.X discloses a method for preparing polyolefins and the polyolefins prepared therefrom, but the supported metallocene catalyst is suitable for preparing polyolefins with high molecular weight and multiple molecular weight distributions, but has no advantage for the preparation of copolymers of propylene and 1-hexene.

[0010] Propylene / ethylene / 1-hexene terpolymers are known in the art and are primarily used in the production of pipes or films. The use of propylene / ethylene / 1-hexene terpolymers in the production of pipes is already known in the industry. Patent CN200580020941.0 relates to a piping system comprising a terpolymer of propylene / ethylene and an α-olefin, wherein the ethylene content is 0% to 9% molar and the 1-hexene content ranges from 0.2 wt% to 5 wt%. This copolymer has a unimodal molecular weight distribution and is used in piping systems. In the examples, the propylene / ethylene / 1-hexene terpolymer has an impact strength of 4.7 KJ / m at -20°C. 2 Elongation at break is 365%.

[0011] Patent CN201280056469.6 describes a pipe containing a terpolymer of propylene, ethylene, and 1-hexene, wherein: (i) the content of 1-hexene-derived units is 1 wt% to 2.6 wt%; (ii) the content of ethylene-derived units is higher than 0.7 wt%, and satisfies the following relationship (1): C2 < C6 - 0.2 (1) where C2 is the content of ethylene-derived units in wt%, and C6 is the content of 1-hexene-derived units in wt%; (iii) the melt flow rate is 0.5 to 3.9 g / 10 min; (iv) the melting temperature range is 130°C to 138°C; preferably 132°C to 136°C. In the embodiment, the container has an impact strength of 8 KJ / m at 0°C. 2 Elongation at break is 360%.

[0012] Patent CN201480030157.7 discloses a container comprising a terpolymer of propylene, ethylene, and 1-hexene. The ethylene content in the copolymer is 0.2 wt% to 1.0 wt%, and the hexene content is 3.5 wt% to 5.5 wt%. The melt flow rate of the copolymer is 15 g / 10 min to 80 g / 10 min. In an embodiment, the container exhibits an impact strength of 1.2 KJ / m at -20°C. 2 .

[0013] Patent CN201580063501.7 discloses a container comprising a terpolymer of propylene, ethylene, and 1-hexene, wherein the ethylene content ranges from 0.6 wt% to 1.1 wt%, and the 1-hexene content ranges from 1.1 wt% to 2.8 wt%. The melt flow rate (MFR) is in the range of 32 to 64 g / 10 min. In the examples, the propylene / 1-hexene copolymer exhibits an impact strength of 3.6 KJ / m at 23°C. 2 .

[0014] Patent CN201410398131.X discloses a solution polymerization method for propylene and α-olefin copolymers, wherein the polymerization temperature and pressure are higher than the supercritical temperature and pressure of the supercritical fluid in the organic solvent, resulting in a propylene / α-olefin copolymer with a high comonomer content. However, the product of this patent does not have the characteristic of low-temperature impact resistance.

[0015] Patent CN200880123593.3 discloses a solution polymerization method. This method is based on an algorithm that predicts the operating parameters of the process. However, this patented method is not suitable for preparing propylene / α-olefin copolymers with low-temperature shock resistance.

[0016] CN201780044093.X provides a composition having 60 wt% to 95 wt% of a first propylene / α-olefin copolymer component and 5 wt% to 40 wt% of a second propylene / α-olefin copolymer component. The method is suitable for two-stage solution polymerization, but the metallocene catalyst used in this patent is not suitable for preparing propylene / α-olefin copolymers with low-temperature shock resistance.

[0017] In the aforementioned prior art, the flexibility of propylene and 1-hexene copolymer products cannot fully meet application requirements. Therefore, the low-temperature impact strength and elongation at break of propylene and 1-hexene copolymers need to be effectively improved. Summary of the Invention

[0018] The main objective of this invention is to provide a polyolefin elastomer, its preparation method, and the metallocene catalyst used therein. The polyolefin elastomer prepared by this invention can balance high toughness and good elongation at break.

[0019] To achieve the above objectives, the present invention provides a metallocene catalyst for the synthesis of polyolefins, the metallocene catalyst having the following structure: Formula I:

[0020]

[0021] Wherein, A is selected from N, S, P, M is a group IVB element, R1-R4 are the same or different and are selected from H, C1-C4 alkyl groups, and R5 and R6 are the same or different and are selected from H, C1-C12 hydrocarbon groups.

[0022] The metallocene catalyst of the present invention, wherein M is Zr, Ti or Hf, and R5 and R6 are the same or different and are selected from H, C1-C12 alkyl, C3-C12 cycloalkyl, C3-C12 cycloolefin, and C6-C12 aryl.

[0023] The metallocene catalyst of this invention, wherein R1-R4 are the same or different and are selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl; R5 and R6 are the same or different and are selected from H, cyclopentadienyl, phenyl, tolyl, xylyl, 1,2-dimethylcyclopentadienyl, 1,3-dimethylcyclopentadienyl, 1,2,3-trimethylcyclopentadienyl, 1,2,4-trimethylcyclopentadienyl, 1,2,3,4-tetramethylcyclopentadienyl, pentamethylcyclopentadienyl, 1,2-diethylcyclopentadienyl, 1,3-diethylcyclopentadienyl, 1,2,4-triethylcyclopentadienyl, 1-methyl-2-ethylcyclopentadienyl, 1-methyl-3-ethylcyclopentadienyl, 1,3-di-n-propylcyclopentadienyl, and 1-methyl-3-n-propylcyclopentadienyl. Dienyl, 1,3-diisopropylcyclopentadienyl, 1-methyl-3-isopropylcyclopentadienyl, 1,3-di-n-butylcyclopentadienyl, 1-methyl-3-n-butylcyclopentadienyl, 1,3-di-sec-butylcyclopentadienyl, 1-methyl-3-sec-butylcyclopentadienyl, 1,3-diisobutylcyclopentadienyl, 1-methyl-3-isobutylcyclopentadienyl, 1,3-di-tert-butylcyclopentadienyl 1-Methyl-3-tert-butylcyclopentadienyl, 1,3-di-n-pentylcyclopentadienyl, 1-methyl-3-n-pentylcyclopentadienyl, 1,3-diisopentylcyclopentadienyl, 1-methyl-3-isopentylcyclopentadienyl, 1,3-di-tert-pentylcyclopentadienyl, 1-methyl-3-tert-pentylcyclopentadienyl, 1,3-dineopeptylcyclopentadienyl and 1-methyl-3-neopeptylcyclopentadienyl.

[0024] To achieve the above objectives, the present invention also provides a method for preparing a polyolefin elastomer, comprising the following steps:

[0025] Propylene is mixed with α-olefins and subjected to solution polymerization under the action of the aforementioned metallocene catalyst. The α-olefins include at least two types of α-olefins containing ethylene. The α-olefins refer to monoolefins with double bonds at the ends of the molecular chain, with the molecular formula R-CH=CH2, where R is H or an alkyl group with two or more carbon atoms.

[0026] The method for preparing polyolefin elastomer according to the present invention further includes: flash evaporation, deashing, and granulation of the mixture after solution polymerization to obtain polyolefin elastomer.

[0027] The method for preparing polyolefin elastomer according to the present invention, wherein the α-olefin is at least two of ethylene and C4-C12 olefins; and the mass ratio of propylene to α-olefin is 97:3-80:20.

[0028] The method for preparing polyolefin elastomer according to the present invention includes a solution polymerization reaction temperature of 70-150℃, preferably 90-120℃, a reaction time of 0.5-3 hours, and a reaction pressure of 0.1-4.0 MPa; a chain transfer regulator is introduced during the reaction, wherein the chain transfer regulator is hydrogen gas, and the amount of the chain transfer regulator added, expressed as H, is 0-15 mmol / mol of chain transfer regulator / propylene.

[0029] The method for preparing polyolefin elastomers according to the present invention includes a solvent in the solution polymerization reaction that is at least one of aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons. The aliphatic hydrocarbon is a C6-C12 straight-chain alkane or kerosene; the alicyclic hydrocarbon is cyclopentane, cyclohexane, methylcyclohexane, or ethylcyclohexane; and the aromatic hydrocarbon is benzene, toluene, or xylene. A co-catalyst is also added to the solution polymerization reaction, and the co-catalyst is an organoaluminum compound.

[0030] To achieve the above objectives, the present invention further provides a polyolefin elastomer obtained by the above preparation method.

[0031] To achieve the above objectives, the present invention further provides a polyolefin elastomer, which is a copolymer of propylene and α-olefin, wherein the propylene content in the copolymer is 80-95 mol%, the copolymer melting point is 85-130℃, and the copolymer impact strength at 0℃-20℃ is 5-20 KJ / m. 2 Preferred strength is 8-15 KJ / m 2 The elongation at break is 500%-1000%, preferably 600%-800%.

[0032] The beneficial effects of this invention are:

[0033] This invention employs a metallocene catalyst with a specific structure to catalyze the solution polymerization of propylene and α-olefins. The resulting copolymer has a melting point of 85-130℃ and a low-temperature (0℃ to -20℃) impact strength of 5-20 KJ / m. 2 With an elongation at break of 500%-1000%, the method of the present invention can obtain polyolefin elastomers with high toughness and good elongation at break. Attached Figure Description

[0034] Figure 1 The NMR spectrum of the propylene ethylene hexyl terpolymer prepared in Example 1 is shown.

[0035] Figure 2 The DSC curve is shown for the propylene-ethylene-hexane terpolymer prepared in Example 1. Detailed Implementation

[0036] The following provides a detailed description of the embodiments of the present invention. These embodiments are implemented based on the technical solution of the present invention and provide detailed implementation methods and processes. However, the scope of protection of the present invention is not limited to the following embodiments. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions.

[0037] This invention discloses a metallocene catalyst for the synthesis of polyolefins, which has the following structure: Formula I:

[0038]

[0039] Wherein, A is selected from N, S, P, M is a group IVB element, R1-R4 are the same or different and are selected from H, C1-C4 alkyl groups, and R5 and R6 are the same or different and are selected from H, C1-C12 hydrocarbon groups.

[0040] In one embodiment, M is Zr, Ti, or Hf, preferably Zr. In one embodiment, the C1-C4 alkyl group is at least one selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, and tert-butyl. In one embodiment, R5 and R6 may be the same or different, and are selected from H, C1-C12 alkyl, C3-C12 cycloalkyl, C3-C12 cycloolefin, and C6-C12 aryl, preferably H or C5-C12 cycloolefin or C6-C12 aryl, such as cyclopentadienyl, phenyl, tolyl, xylyl, 1,2-dimethylcyclopentadienyl, 1,3-dimethylcyclopentadienyl, 1,2, 3-Trimethylcyclopentadienyl, 1,2,4-Trimethylcyclopentadienyl, 1,2,3,4-Tetramethylcyclopentadienyl, Pentamethylcyclopentadienyl, 1,2-Diethylcyclopentadienyl, 1,3-Diethylcyclopentadienyl, 1,2,4-Triethylcyclopentadienyl, 1-Methyl-2-ethylcyclopentadienyl, 1-Methyl-3-ethylcyclopentadienyl, 1,3-Di-n-propylcyclopentadienyl, 1-Methyl -3-n-propylcyclopentadienyl, 1,3-diisopropylcyclopentadienyl, 1-methyl-3-isopropylcyclopentadienyl, 1,3-di-n-butylcyclopentadienyl, 1-methyl-3-n-butylcyclopentadienyl, 1,3-di-sec-butylcyclopentadienyl, 1-methyl-3-sec-butylcyclopentadienyl, 1,3-diisobutylcyclopentadienyl, 1-methyl-3-isobutylcyclopentadienyl, 1,3-di-tert-butylcyclopentadienyl Pentadienyl, 1-methyl-3-tert-butylcyclopentadienyl, 1,3-di-n-pentylcyclopentadienyl, 1-methyl-3-n-pentylcyclopentadienyl, 1,3-diisopentylcyclopentadienyl, 1-methyl-3-isopentylcyclopentadienyl, 1,3-di-tert-pentylcyclopentadienyl, 1-methyl-3-tert-pentylcyclopentadienyl, 1,3-dineopeptylcyclopentadienyl and 1-methyl-3-neopeptylcyclopentadienyl.

[0041] In one embodiment, the present invention also provides a method for preparing the above-mentioned metallocene catalyst (A is S, M is Zr, R1-R4 are -CH3, R5 and R6 are cyclopentyl), as shown in Formula 1, comprising the following steps:

[0042]

[0043] (1) Synthesis of cyclopentyl[b]thiophene: 3-bromothiophene was directionally lithiated with lithium diisopropylamide (LDA) at -78 °C, and then methylated with iodomethane to give 2-methyl-3-bromothiophene (product 1); in diethyl ether (Et2O), at room temperature (25 °C) with nickel bis(diphenylphosphine)dichloride (Ni(dppp)Cl2) as catalyst, product 1 was coupled with magnesium cyclohexyl bromide (CHMgBr) to give disubstituted product 2; product 2 was reacted with methacrylic acid (MAA) (87% polyphosphoric acid (PPA) solution) to give product 3; 300 mmol lithium aluminum hydride (LiAlH4) in diethyl ether solution was reacted with product 3 in tetrahydrofuran (THF) solution at room temperature to give hydroxylated product 4; finally, product 4 was dissolved in toluene, p-toluenesulfonic acid (p-TSA) was added and reacted, and the product was dried and purified to give C2-symmetric metallocene ligand (product 5).

[0044] (2) Silicon bridging: Product 5 was dissolved in tetrahydrofuran solution, and a 2.5M n-butyllithium (n-BuLi)heptane solution was added dropwise to deprotonate ligand product 5. The reaction was carried out at room temperature for 5 hours. A tetrahydrofuran solution containing dichlorodimethylsilane was added dropwise to the obtained anionic product, and the reaction was carried out at room temperature for 6 hours to obtain the dimethylsilane-bridged product.

[0045] (3) Preparation of metallocene catalyst: The dimethylsilane-bridged product was dissolved in diethyl ether solution, and n-butyllithium hexane solution (2.5M) was added to it. After reacting for 5 hours, zirconium tetrachloride (ZrCl4) was added and reacted for 2 hours. After filtration, a mixture of racemic and meso compounds in a ratio of 3:5 was obtained. The racemic product was separated and purified to obtain the structure shown in Formula 1.

[0046] The metallocene catalyst described above in this invention is used to catalyze the preparation of polyolefin elastomers, resulting in elastomers with high toughness and high elongation at break. In one embodiment, the metallocene catalyst of this invention is used for the solution synthesis of polyolefins; in another embodiment, the metallocene catalyst of this invention is used for the synthesis of terpolymers, such as the synthesis of terpolymer polypropylene.

[0047] In one embodiment, the method for preparing the polyolefin elastomer of the present invention includes the following steps:

[0048] Propylene and α-olefins were mixed and subjected to solution polymerization under the action of the aforementioned metallocene catalyst to obtain a mixture.

[0049] In another embodiment, the method for preparing the polyolefin elastomer of the present invention further includes: flash evaporation, deashing, and granulation of the mixture after solution polymerization to obtain the polyolefin elastomer.

[0050] In one embodiment, the α-olefin of the present invention is at least two of ethylene and C4-C12 olefins, that is, the polymerization system of the present invention is a ternary copolymer system, including propylene and two other copolyolefin monomers. In another embodiment, the α-olefin of the present invention includes ethylene and one of C4-C12 olefins, such as 1-hexene; in yet another embodiment, the mass ratio of propylene to α-olefin of the present invention is 97:3-80:20.

[0051] The method for preparing polyolefin elastomers of the present invention further includes the addition of an organoaluminum co-catalyst during the solution polymerization reaction. In one embodiment, the co-catalyst is an alkylaluminum compound, such as methylaluminoxane, modified methylaluminoxane, or a mixture of both.

[0052] In one embodiment, the solution polymerization reaction temperature of the present invention is 80-150°C, the reaction time is 0.5-3 hours, and the reaction pressure is 0.1-4.0 MPa; a chain transfer regulator may be introduced during the reaction, such as hydrogen gas, and the amount of chain transfer regulator added, expressed as H, is 0-15 mmol / mol of chain transfer regulator / propylene.

[0053] This invention does not specifically limit the type of solvent used in the solution polymerization reaction. In one embodiment, the solvent is at least one selected from aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons. Aliphatic hydrocarbons are, for example, C6-C12 straight-chain alkanes or kerosene; alicyclic hydrocarbons are, for example, cyclopentane, cyclohexane, methylcyclohexane, or ethylcyclohexane; and aromatic hydrocarbons are, for example, benzene, toluene, or xylene. In another embodiment, the solid content (polypropylene copolymer) in the solution polymerization reaction system is 20%-60 wt%.

[0054] This invention does not specifically limit the flash evaporation, deashing, and granulation methods; conventional methods in the art are sufficient. In one embodiment, the flash evaporation temperature is 150-270°C.

[0055] Therefore, this invention provides a method for preparing propylene-α-olefin terpolymers using a bridged metallocene catalyst containing heterocyclic structures. By controlling the copolymerization amount and distribution of the two α-olefins, a propylene-based polyolefin elastomer is obtained using a solution method. The copolymer obtained by this invention has an ash content of 5-70 ppm after deashing, a propylene content of 80-95 mol%, a melting point of 85-130℃, and a low-temperature (0℃ to -20℃) impact strength of 5-20 KJ / m.2 The elongation at break is 500%-1000%.

[0056] The technical solution of the present invention will be further described below through specific embodiments. However, the following embodiments should not be construed as limiting the scope of protection of the present invention. Any improvements made on the basis of the present invention are within the scope of protection of the present invention.

[0057] Test method:

[0058] (1) Melting temperature and crystallization temperature:

[0059] The measurements were performed using a differential scanning calorimeter (Q2000, PerkinElmer). The temperature was rapidly increased from 50°C to 200°C and held for 5 minutes to eliminate thermal history. The temperature was then decreased to 50°C at a rate of 10°C / min and held for 5 minutes to obtain the crystallization temperature Tc and enthalpy change ΔHc of the polymer. After holding for 5 minutes, the temperature was increased to 200°C at a rate of 10°C / min to obtain the melting temperature Tm and enthalpy change ΔHm of the polymer. The crystallinity of polypropylene was defined as the ratio of the measured enthalpy of melting to the standard enthalpy of melting of fully crystallized polypropylene (209 J / g).

[0060] (2) Spline preparation:

[0061] Standard specimens for mechanical property testing were injection molded using an SZ-15 hydraulic injection molding machine at an injection pressure of 100 kgt / cm². 3 The injection time was 9.5 seconds, the holding pressure was 15 seconds, and the injection temperature was 180℃. The injection-molded specimens were placed in a desiccator at room temperature for more than 24 hours. The notched impact specimens were then milled with standard notches on a notched prototyping machine and annealed in a desiccator at room temperature for more than 24 hours.

[0062] (3) Impact strength test:

[0063] The notched impact strength of the samples was determined on a CSI-137C impact testing machine according to ASTM D256 standard. For the low-temperature simply supported beam impact strength test, the samples with a standard notch milled were first placed in a -20°C freeze-drying oven for 2 hours to cool, and then their impact strength was quickly tested.

[0064] (4) Elongation at break

[0065] The elongation at break of the samples was determined using an Instron 5566 universal testing machine according to GB / T 1040.1-2006. The test temperature was 25℃.

[0066] (5) Melt flow index test:

[0067] The test was conducted using a Haake 556-0031 melt indexer from Germany, with a load of 2.16 kg and a temperature of 230 °C.

[0068] Catalyst preparation in the following examples:

[0069] (1) Synthesis of cyclopentyl[b]thiophene (as shown in Formula 1): 100 g of 3-bromothiophene was directionally lithiated with 610 mmol of lithium diisopropylamide (LDA) at -78 °C, followed by methylation with 68.5 g of iodomethane to give 2-methyl-3-bromothiophene (product 1) in 75% yield; in diethyl ether (Et2O), at room temperature (25 °C) with 1 g of bis(diphenylphosphine) nickel dichloride (Ni(dppp)Cl2) as a catalyst, 89.8 g of product 1 was coupled with 456 mmol of cyclohexyl magnesium bromide (or cyclopentadienyl magnesium bromide, phenyl magnesium bromide) to give disubstituted product 2 in 85% yield; 124.7 g of product 2 was then coupled with 61.7 g of methyl ether (LDA) to give 2-methyl-3-bromothiophene (product 1) in 610 mmol of iodomethane. The product 3 was obtained by reacting hydroxylated acrylic acid (MAA) with an 87% polyphosphoric acid (PPA) solution to give product 3, with a yield of 82%. 202g of product 3 was reacted with a solution of 300mmol lithium aluminum hydride (LiAlH4) in diethyl ether at room temperature in a tetrahydrofuran (THF) solution to give hydroxylated product 4, with a yield of 75%. Finally, 28g of product 4 was dissolved in toluene, and 1g of p-toluenesulfonic acid (p-TSA) was added to react with the product. After drying and purification, a C2-symmetric metallocene ligand (product 5) was obtained, with a yield of 90%.

[0070] (2) Silicon bridging: 22.6 g of product 5 was dissolved in tetrahydrofuran solution, and a 2.5 M n-butyllithium (n-BuLi)heptane solution was added dropwise to deprotonate ligand product 5. The reaction was carried out at room temperature for 5 hours. A tetrahydrofuran solution containing 6.45 g of dichlorodimethylsilane was added dropwise to the obtained anionic product, and the reaction was carried out at room temperature for 6 hours to obtain the dimethylsilane-bridged product.

[0071] (3) Preparation of metallocene catalyst: 1.82 g of dimethylsilane-bridged product was dissolved in 100 ml of diethyl ether solution, and 2.5 ml of n-butyllithium hexane solution (2.5 M) was added. After reacting for 5 hours, 0.83 g of zirconium tetrachloride (ZrCl4) was added and reacted for 2 hours. After filtration, a mixture of racemic and meso compounds in a ratio of 3:5 was obtained. After separation and purification, 350 mg of racemic product (structure shown in Formula 1) was obtained, with a yield of 47%.

[0072] The prepared metallocene compound was analyzed by a high-resolution FT-MS mass spectrometer (Solarix 9.4T) from Bruker, confirming that it was indeed the target structure.

[0073] Example 1

[0074] A 5L high-pressure reactor was heated to 90℃ and evacuated and purged with nitrogen three times to remove moisture and air, maintaining a nitrogen atmosphere. Then, 0.39 mol of 1-hexene monomer, approximately 1 μmol of the metallocene catalyst of this invention (where A is S, M is Zr, R1-R4 are -CH3, and R5 and R6 are cyclopentadienyl), 10 ml of a toluene solution of methylaluminoxane (MAO) (1 mmol / ml), and 1 L of anhydrous cyclohexane were added sequentially to the reactor. Then, 800 g (19.05 mol) of propylene and 16 g (0.57 mol) of ethylene were introduced. The reactor was sealed and heated to 90℃, and the reaction was stirred for 1 hour. After 1 hour, stirring was stopped, and the product was degassed, flash-evaporated (flash temperature 220℃), and then extruded and granulated using a screw extruder to obtain 249 g of white polypropylene copolymer granules. The test results of the product are shown in Table 1. The NMR spectrum of the propylene-ethylene-hexylene terpolymer is shown in Table 1. Figure 1 The DSC curve of the propylene-ethylene-hexylene terpolymer is shown in [reference needed]. Figure 2 .

[0075] Example 2

[0076] In Example 1, "0.39 mol of 1-hexene monomer" was changed to "0.60 mol of 1-octene monomer"; "flash evaporation (flash evaporation temperature 220℃)" was changed to "flash evaporation (flash evaporation temperature 200℃)"; other conditions remained the same as in Example 1. 239 g of white polypropylene copolymer granules were obtained, and the test results of the product are shown in Table 1.

[0077] Example 3

[0078] A 5L high-pressure reactor was heated to 100℃ and evacuated and purged with nitrogen three times to remove moisture and air, maintaining a nitrogen atmosphere. Then, 0.39 mol of 1-hexene monomer, approximately 1 μmol of metallocene catalyst (where A is S, M is Zr, R1-R4 are -CH3, and R5 and R6 are phenyl), 10 ml of a toluene solution of methylaluminoxane (MAO) (1 mmol / ml), and 1 L of anhydrous cyclohexane were sequentially added to the reactor. Next, 800 g (19.05 mol) of propylene and 18.8 g (0.67 mol) of ethylene were introduced. The reactor was sealed and heated to 70℃, and the reaction was stirred for 1 hour. After 1 hour, stirring was stopped, and the product was degassed, flash-evaporated (flash temperature 220℃), and then extruded and granulated using a screw extruder to obtain 278 g of white polypropylene copolymer granules. The test results of the product are shown in Table 1.

[0079] Example 4

[0080] A 5L high-pressure reactor was heated to 90℃ and evacuated and purged with nitrogen three times to remove moisture and air, maintaining a nitrogen atmosphere. Then, 0.39 mol of 1-decene monomer, approximately 1 μmol of metallocene catalyst (where A is S, M is Zr, R1-R4 are H, and R5 and R6 are phenyl), 10 ml of a toluene solution of methylaluminoxane (MAO) (1 mmol / ml), and 1 L of anhydrous xylene were added sequentially to the reactor. 5.1 mmol of hydrogen, 800 g (19.05 mol) of propylene, and 32 g (1.14 mol) of ethylene were then introduced. The reactor was sealed and heated to 90℃, and the reaction was stirred for 1 hour. After 1 hour, stirring was stopped, and the product was degassed, flash-evaporated (flash temperature 220℃), and then extruded and granulated using a screw extruder to obtain 397 g of white polypropylene copolymer granules. The test results of the product are shown in Table 1.

[0081] Example 5

[0082] A 5L high-pressure reactor was heated to 70°C and evacuated and purged with nitrogen three times to remove moisture and air, maintaining a nitrogen atmosphere. Then, 50 mL (0.39 mol) of 1-hexene monomer, approximately 1 μmol of metallocene catalyst (where A is S, M is Zr, R1 and R4 are H, R2 and R3 are -CH3, and R5 and R6 are phenyl), 10 mL of a toluene solution of methylaluminoxane (MAO) (1 mmol / mL), and 1 L of anhydrous cyclohexane were sequentially added to the reactor. Then, 10.2 mmol of hydrogen, 800 g (19.05 mol) of propylene, and 18.8 g (0.67 mol) of ethylene were introduced. The reactor was sealed and heated to 70°C, and the reaction was stirred for 1 hour. After reacting for 1 hour, stirring was stopped, and the product was degassed and flashed (flash temperature 220℃) before being fed into a screw for extrusion granulation to obtain 184g of white polypropylene copolymer granules. The test results of the product are shown in Table 1.

[0083] Example 6

[0084] A 5L high-pressure reactor was heated to 90℃ and evacuated and purged with nitrogen three times to remove moisture and air, maintaining a nitrogen atmosphere. Then, 75ml (0.60mol) of 1-hexene monomer, approximately 1μmol of metallocene catalyst (where A is S, M is Zr, R1 and R4 are -CH3, R2 and R3 are H, and R5 and R6 are phenyl), 10ml of a toluene solution of methylaluminoxane (MAO) (1mmol / ml), and 1L of anhydrous cyclohexane were sequentially added to the reactor. Then, 800g (19.05mol) of propylene and 32g (1.14mol) of ethylene were introduced. The reactor was sealed and heated to 90℃, and the reaction was stirred for 1 hour. After 1 hour, stirring was stopped, and the product was degassed, flash-evaporated (flash temperature 250℃), and then extruded and granulated using a screw extruder to obtain 349g of white polypropylene copolymer granules. The test results of the product are shown in Table 1.

[0085] Comparative Example 1

[0086] Except for the use of a metallocene catalyst represented by the following chemical formula, all other conditions were the same as in Example 1. 258 g of white polypropylene copolymer particles were obtained, and the test results of the product are shown in Table 1.

[0087]

[0088] Comparative Example 2

[0089] A 5L high-pressure reactor was heated to 90°C and evacuated and purged with nitrogen three times to remove moisture and air, maintaining a nitrogen atmosphere. Then, 50 ml (0.39 mol) of 1-hexene monomer, approximately 1 μmol of metallocene catalyst (where A is S, M is Zr, R1-R4 are -CH3, and R5 and R6 are cyclopentadienyl), 10 ml of a toluene solution of methylaluminoxane (MAO) (1 mmol / ml) were added, followed by the introduction of 5.1 mmol of hydrogen, 1200 g (28.58 mol) of propylene, and 18.8 g (0.67 mol) of ethylene. The reactor was sealed and heated to 90°C, and the reaction was stirred for 1 hour. After 1 hour, stirring was stopped, and unreacted olefin gas was released. The product was hard and could not be discharged normally.

[0090] Comparative Example 3

[0091] A 5L high-pressure reactor was heated to 90℃ and evacuated and purged with nitrogen three times to remove moisture and air, maintaining a nitrogen atmosphere. Then, 1.9 mol of 1-octene monomer, approximately 1 μmol of metallocene catalyst (where A is S, M is Zr, R1-R4 are -CH3, and R5 and R6 are cyclopentadienyl), 10 ml of a toluene solution of methylaluminoxane (MAO) (1 mmol / ml), and 1 L of toluene were sequentially added to the reactor, followed by the introduction of 800 g (19.05 mol) of propylene. The reactor was sealed and heated to 90℃, and the reaction was stirred for 1 h. After 1 h, stirring was stopped, and the product was degassed, flash-evaporated (flash temperature 220℃), and then extruded and granulated using a screw extruder to obtain 208 g of white polypropylene copolymer granules. The test results of the product are shown in Table 1.

[0092] Table 1. Test results of copolymers in Examples 1-6 and Comparative Examples 1, 2, and 3.

[0093]

[0094] As shown in Table 1, Comparative Example 2 uses a bulk polymerization process, which is difficult to operate industrially. Comparative Document 3 uses the metallocene catalyst of this invention for binary copolymerization; the resulting polymer has lower low-temperature impact strength and slightly lower elongation at break compared to the polymers obtained from the ternary copolymerization of Examples 1-6 of this invention. Examples 1-6 of this invention use a metallocene catalyst combined with solution polymerization for ternary copolymerization, resulting in polymers with significantly improved performance, significantly increased low-temperature impact strength, and higher elongation at break. Therefore, the copolymers obtained by the method of this invention not only possess flexibility but also excellent low-temperature impact resistance.

[0095] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a polyolefin elastomer, characterized in that, Includes the following steps: Propylene is mixed with α-olefins and subjected to solution polymerization in the presence of a metallocene catalyst and a co-catalyst. The α-olefins are at least two types of α-olefins, including ethylene. The mass ratio of propylene to α-olefins is 97:3-80:

20. The co-catalyst is an organoaluminum compound. The metallocene catalyst has the following structure: Formula I Wherein, A is S, M is Zr, R1-R4 are the same or different and are selected from H, C1-C4 alkyl groups, and R5 and R6 are the same or different and are selected from H, C1-C12 hydrocarbon groups.

2. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, M is Zr, and R5 and R6 may be the same or different, selected from H, C1-C12 alkyl, C3-C12 cycloalkyl, C3-C12 cycloolefin, and C6-C12 aryl.

3. The method for preparing the polyolefin elastomer according to claim 2, characterized in that, R1-R4 may be the same or different, selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl; R5 and R6 may be the same or different, selected from H, cyclopentadienyl, phenyl, tolyl, xylylene, 1,2-dimethylcyclopentadienyl, 1,3-dimethylcyclopentadienyl, 1,2,3-trimethylcyclopentadienyl, 1,2,4-trimethylcyclopentadienyl, 1,2,3,4-tetramethylcyclopentadienyl, pentamethylcyclopentadienyl, 1,2-diethylcyclopentadienyl, 1,3-diethylcyclopentadienyl, 1,2,4-triethylcyclopentadienyl, 1-methyl-2-ethylcyclopentadienyl, 1-methyl-3-ethylcyclopentadienyl, 1,3-di-n-propylcyclopentadienyl, 1,3- Diisopropylcyclopentadienyl, 1-methyl-3-isopropylcyclopentadienyl, 1,3-di-n-butylcyclopentadienyl, 1-methyl-3-n-butylcyclopentadienyl, 1,3-di-sec-butylcyclopentadienyl, 1-methyl-3-sec-butylcyclopentadienyl, 1,3-diisobutylcyclopentadienyl, 1-methyl-3-isobutylcyclopentadienyl, 1,3-di-tert-butylcyclopentadienyl, 1-methyl 1,3-tert-butylcyclopentadienyl, 1,3-di-n-pentylcyclopentadienyl, 1-methyl-3-n-pentylcyclopentadienyl, 1,3-diisopentylcyclopentadienyl, 1,3-di-tert-pentylcyclopentadienyl, 1-methyl-3-tert-pentylcyclopentadienyl, 1,3-dineopeptylcyclopentadienyl and 1-methyl-3-neopeptylcyclopentadienyl.

4. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, Also includes: The mixture after solution polymerization is flash-evaporated, deashed, and granulated to obtain polyolefin elastomer.

5. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, The solution polymerization reaction temperature is 70-150℃, the reaction time is 0.5-3 hours, and the reaction pressure is 0.1-4.0 MPa. During the reaction, a chain transfer regulator, which is hydrogen gas, is introduced. The amount of chain transfer regulator added, expressed as H, is 0-15 mmol / mol of chain transfer regulator / propylene.

6. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, The solution polymerization reaction temperature is 90-120℃.

7. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, The solvent in the solution polymerization reaction is at least one of aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons. The aliphatic hydrocarbons are C6-C12 straight-chain alkanes or kerosene; the alicyclic hydrocarbons are cyclopentane, cyclohexane, methylcyclohexane, or ethylcyclohexane; and the aromatic hydrocarbons are benzene, toluene, or xylene.

8. The polyolefin elastomer obtained by the preparation method according to any one of claims 1-7.

9. The polyolefin elastomer according to claim 8, characterized in that, The copolymer of propylene and α-olefin contains 80-95 mol% propylene, has a melting point of 85-130℃, and an impact strength of 5-20 KJ / m² at 0℃-20℃. 2 The elongation at break is 500%-1000%.

10. The polyolefin elastomer according to claim 9, characterized in that, The impact strength of the copolymer at 0℃-20℃ is 8-15KJ / m. 2 The elongation at break is 600%-800%.

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