Preparation method of polyolefin elastomer

Abstract

The invention discloses a preparation method of a polyolefin elastomer, which comprises the following steps: carrying out gas-phase polymerization on ethylene and alpha-olefin under the action of metallocene catalyst solid particles and an antistatic agent to obtain the polyolefin elastomer, wherein the metallocene catalyst solid particles are prepared by using components including a metallocene compound, an organic boron compound and silica gel as raw materials through a spray drying method, and the structural formula of the metallocene compound is shown in the specification; the organic boron compound is N, N-dimethyl phenylammonium tetrakis (perfluorophenyl) borate. Compared with the prior art, the ethylene / alpha-olefin random copolymer can be prepared without using expensive cocatalysts such as MAO or MMAO, the consumption of organic boride of the cocatalysts is relatively low, the number of flakes and blocks caused by static electricity of polymer powder is small, the particle morphology is good, and the method has a good application prospect.

Description

Technical Field

[0001] This invention relates to a method for preparing polyolefin elastomers, particularly ethylene / α-olefin random copolymers (POE). Background Technology

[0002] Polyolefin elastomers are a class of polyolefin materials copolymerized from ethylene and propylene or other α-olefins (such as 1-butene, 1-hexene, 1-octene, etc.). Compared with polyolefin plastics, they have a higher content of comonomers in their molecular chains and a lower density. Currently, polyolefin elastomers mainly fall into two categories: ethylene-propylene copolymers and ethylene / α-olefin copolymers. Ethylene-propylene copolymer elastomers include ethylene-propylene-diene monomer (EPM) rubber and ethylene-propylene-diene monomer (EPDM) rubber, while ethylene / α-olefin copolymer elastomers mainly include ethylene / α-olefin random copolymers (POE) and ethylene / α-olefin block copolymers (OBC). Due to its unique performance advantages in the emerging photovoltaic encapsulant film field, the market demand for ethylene / α-olefin random copolymers (POE) has increased significantly.

[0003] Metallocene catalysts with special structures, used in the copolymerization of ethylene / α-olefins, exhibit characteristics such as narrow molecular weight distribution, strong copolymerization ability, precise and controllable chain structure, and high product purity. They are the main catalyst type currently used in the field of ethylene / α-olefin random copolymers (POE). MAO or MMAO are often used as co-catalysts, but their high price and large consumption lead to high catalyst costs in polymer production.

[0004] In existing technologies, ethylene / α-olefin random copolymers (POE) are mainly produced by homogeneous solution polymerization. Chinese invention patent CN118221858A discloses a method for preparing polyolefin elastomer POE for photovoltaic encapsulation. Ethylene, comonomers, organic solvents, and main and co-catalysts are added to a stirred polymerization reactor under anhydrous and oxygen-free conditions to react and obtain the elastomer POE; this is a solution polymerization process. Chinese invention patent CN116789883A discloses a polyolefin elastomer and its application in photovoltaic encapsulation films. Its elastomer preparation steps clearly specify that the solvent is mixed with α-olefins and then injected into the reactor, which is a solution polymerization process. The composition prepared from this elastomer exhibits superior optical properties, electrical insulation properties, and PID resistance in photovoltaic encapsulation films. Chinese invention patent CN116041598A discloses an olefin polymer for photovoltaic films and its solution polymerization method. This method yields an olefin polymer for photovoltaic films with improved PID resistance. Chinese invention patent CN115746746A discloses a polyolefin elastomer composition for photovoltaic encapsulation films, wherein the polyolefin elastomer is obtained by solution polymerization. Analysis revealed the relationship between the POE structure and the properties of the polyolefin elastomer composition, thus ensuring that the light transmittance, water vapor transmission rate, and volume resistivity of the polyolefin elastomer composition remain at a high level. Chinese invention patent CN117567961B discloses an ethylene / α-olefin random copolymer for photovoltaic encapsulant films and its applications. The copolymer exhibits rapid crosslinking and high crosslinking degree in photovoltaic encapsulant film applications, resulting in high light transmittance of the photovoltaic encapsulant film. It specifies that the copolymer is prepared using a batch reactor and solution polymerization process.

[0005] Chinese invention patent CN119285815 discloses a method for preparing polyolefin elastomers via a heterogeneous-gas phase method. The method utilizes a coated and modified zirconium diacene main catalyst and a butylaluminoxane co-catalyst to prepare the polyolefin elastomer in gas phase polymerization. The uniformity of polymer monomer insertion into the molecular chain segments is improved, and the light transmittance of the product is also enhanced.

[0006] Gas-phase polymerization offers advantages such as relatively mild reaction conditions, lower investment in production equipment, lower energy and material consumption, and lower product odor, making it a preferred polymerization route for many olefin polymer products prepared using metallocene catalysts. However, in gas-phase polymerization, metallocene polyethylene products are prone to static electricity. To avoid negative consequences such as polymer powder sticking to walls, clumping, and difficulty in discharging due to static electricity, higher requirements are placed on the supported metallocene catalyst, the particle morphology of the polymer, and the static electricity level in the reaction system when producing low-density polyolefin elastomers.

[0007] Studies have shown that organoboron compounds with adapted structures can activate metallocene compounds for olefin polymerization or copolymerization. However, since the matched organoboron compounds are all solids and have low solubility in low-boiling-point alkane organic solvents such as hexane at conventional polymerization temperatures, their application has been limited to solution polymerization processes. Therefore, researching and developing a heterogeneous metallocene catalyst system composed of metallocene compounds with adapted structures and organoboron compounds, and applying it to the gas-phase preparation of ethylene / α-olefin random copolymers (POE), is of practical significance. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a method for preparing polyolefin elastomers.

[0009] To address the aforementioned problems, this invention provides a method for preparing a polyolefin elastomer, which is obtained by gas-phase polymerization of ethylene and α-olefins under the action of metallocene catalyst solid particles and an antistatic agent; wherein, the metallocene catalyst solid particles are prepared by spray drying using components comprising metallocene compounds, organoboron compounds and silica gel, and the structural formula of the metallocene compounds is shown in Formula 1: Formula 1; In Formula 1, n is a natural number from 4 to 10; R1 and R2 may be the same or different, and each is independently an aryl group having 6 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms substituted with an alkyl group having 1 to 20 carbon atoms; R3 is an alkyl group having 1 to 20 carbon atoms; R4 is a tertiary amine having an alkyl group having 1 to 10 carbon atoms; A is carbon, silicon, or germanium; the two Xs may be the same or different, and each is independently a halogen or an alkyl group having 1 to 20 carbon atoms.

[0010] Preferably, the organoboron compound is N,N-dimethylphenylammonium tetra(perfluorophenyl)borate.

[0011] Preferably, the silica gel is a fumigated silica gel with an average particle size of less than 1 μm. This type of silica gel is prepared by a gas-phase method and typically has a specific surface area of ​​200 m². 2 Approximately / g. This is an example, but not limited to, Cabot's atomized silica gel products such as TS-530, TS-610, and TS-720.

[0012] Preferably, the metallocene compound comprises one or more compounds with the following structural formulas: Formula 2; Formula 3; Equation 4; Formula 5; Formula 6; Formula 7.

[0013] Preferably, the metallocene catalyst solid particles comprise, by mass percentage, 0.2-10% metallocene compound, 5-50% organoboron compound, 20-80% silica gel, with the balance being an inert solvent, and have an average particle size of 5-100 μm.

[0014] Preferably, the metallocene catalyst solid particles comprise, by mass percentage, 0.5-5% metallocene compound, 20-40% organoboron compound, and 30-60% silica gel, with the balance being an inert organic solvent. The average particle size is 10-60 μm. The inert organic solvent may be optionally those capable of dissolving the metallocene compound of Formula 1 and N,N-dimethylphenylammonium tetra(perfluorophenyl)borate, and having a boiling point not exceeding 150°C. Generally, tetrahydrofuran is preferred for economic and availability reasons.

[0015] Preferably, the method for preparing the metallocene catalyst solid particles includes the following steps: Step a): The metallocene compound of Formula 1 and N,N-dimethylphenylammonium tetra(perfluorophenyl)borate are completely dissolved in an inert organic solvent to obtain a homogeneous liquid. The silica gel is then mixed with the above liquid to obtain the masterbatch to be sprayed. Step b): The masterbatch obtained in step a) is spray-dried to obtain spherical metallocene catalyst particles.

[0016] In step a), there are no special requirements for the process of dissolving the metallocene compound and organoboron compound and mixing them with silica gel to prepare the masterbatch to be sprayed. The proportion of additives is determined according to the requirements of the metallocene catalyst. There are no special requirements for the dissolution temperature and time. Any inert organic solvent can be used if it is below the reflux temperature and can dissolve the metallocene compound and organoboron compound. The amount of inert organic solvent added should be such that it can completely dissolve the metallocene compound and organoboron compound and the solid content in the subsequent masterbatch is suitable for spray drying to obtain well-shaped solid particles.

[0017] More preferably, step a) specifically involves: adding the metallocene compound and N,N-dimethylphenylammonium tetra(perfluorophenyl)borate to tetrahydrofuran, heating to 50°C-reflux temperature, stirring and dissolving for 0.5-10 hours, and after complete dissolution, adjusting the solution temperature to 20-50°C, adding silica gel, and stirring to mix evenly to obtain the masterbatch to be sprayed; the mass ratio of metallocene compound, organoboron compound, tetrahydrofuran, and silica gel is 0.2-10:5-50:200-1000:20-80.

[0018] More preferably, step a) specifically involves: adding the metallocene compound and N,N-dimethylphenylammonium tetra(perfluorophenyl)borate to tetrahydrofuran, heating to 60°C-reflux temperature, stirring and dissolving for 0.5-10 hours, and after complete dissolution, adjusting the temperature to 30-45°C, adding silica gel, and stirring to mix evenly to obtain the masterbatch to be sprayed; the mass ratio of metallocene compound, organoboron compound, tetrahydrofuran, and silica gel is 0.5-5:20-40:300-500:30-50.

[0019] Step b) involves a spray drying process, and the equipment and conditions used in the spray drying process are not particularly limited. Any existing equipment and methods suitable for spray drying organic phase materials can be incorporated into this invention. The spray drying equipment can be a pressure spray dryer, a rotary spray dryer, or a two-fluid spray dryer. The material drying process can be completed in one step by the spray dryer, or one or more other types of drying equipment (such as fluidized bed dryers) can be connected in series after the spray dryer to continue drying until complete. In small-scale experiments, two-fluid spray dryers are often used as experimental platforms for the spray drying preparation of microspheres due to their smaller size and wider adjustable particle size range. As an example, a two-fluid spray dryer is used for atomization and drying of the material to be sprayed. The spray drying process is carried out under an inert atmosphere (nitrogen), and the carrier gas is dried nitrogen. The spray drying yield is controlled by the feed flow rate of the masterbatch to be sprayed, the solvent content of the catalyst particles is adjusted by the outlet temperature, the particle size of the catalyst is adjusted by the ratio of the atomizing gas flow rate to the feed flow rate of the masterbatch to be sprayed, and the morphology of the catalyst particles is adjusted by the synergistic effect of drying temperature and masterbatch composition. The inlet temperature of the carrier gas is 120-200℃, the outlet temperature is 70-135℃, the atomizing gas is dried nitrogen, and the pressure of the atomizing gas is 3-6 bar.

[0020] The inventors discovered in their research that the metallocene catalyst solid particles and the polysulfone antistatic agent composition in the metallocene catalyst system of this invention exhibit a good synergistic effect. When applied to the gas-phase polymerization preparation of polyolefin elastomers, it demonstrates high activity and copolymerization performance. By using a spray-drying molding method, the co-catalyst N,N-dimethylphenylammonium tetra(perfluorophenyl)borate and the metallocene compound are assembled into the metallocene catalyst solid particles, with both uniformly distributed within the catalyst particles. Compared to the method of separately introducing the main catalyst and co-catalyst into the reactor for contact activation, this method allows for more thorough contact between the main catalyst and co-catalyst, shortening the activation response time of the main catalyst, improving the polymerization activity of the main catalyst, and also increasing the utilization efficiency of the co-catalyst, thus reducing its usage. Furthermore, within the catalyst solid particles, the co-catalyst N,N-dimethylphenylammonium tetra(perfluorophenyl)borate acts as a binder, significantly improving the strength of the metallocene catalyst solid particles, which are primarily composed of atomized silica gel.

[0021] Preferably, the antistatic agent can be one commonly used in olefin polymerization processes. These antistatic agents include, but are not limited to, carboxylates, aliphatic amines, and polysulfones. All of these antistatic agents can inhibit the agglomeration of polymer powder caused by static electricity during polymerization. However, from the perspective of antistatic efficiency, antistatic agents containing polysulfone compositions are more effective. The polysulfone composition comprises a polysulfone copolymer and at least one component selected from polymeric polyamines and oil-soluble sulfonic acids. Preferably, the polysulfone composition comprises a mixture of polysulfone copolymers, polymeric polyamines, and oil-soluble sulfonic acids.

[0022] More preferably, the polysulfone copolymer component in the polysulfone composition is a polymer, preferably a linear polymer, wherein the structure is considered to be an alternating copolymer of olefin and sulfur dioxide, having a comonomer and olefin arranged end-to-end in a 1:1 molar ratio. Preferably, the polysulfone copolymer is substantially composed of about 50 mol% sulfur dioxide units, about 40-50 mol% units derived from one or more 1-olefins each having about 6-24 carbon atoms, and about 0-10 mol% units derived from olefins having the formula ACH=CHB, wherein A is a group having the general formula -(CH)-COOH, wherein x is 0-17, and B is hydrogen or carboxyl x2x group, provided that when B is carboxyl, x is 0, and wherein A and B together can be dicarboxylic anhydride groups.

[0023] Preferably, the weight-average molecular weight of the polysulfone copolymer of the present invention is in the range of 10,000 to 1,500,000, more preferably 50,000 to 900,000. The unit derived from one or more 1-olefins is preferably derived from a straight-chain olefin having 6 to 18 carbon atoms, such as 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, and 1-octadecene. Examples of units derived from one or more compounds of the general formula ACH=CHB are units derived from maleic acid, acrylic acid, and 5-hexenoic acid. A preferred polysulfone copolymer is 1-decene polysulfone, which has a specific logarithmic viscosity in the range of about 0.04 dl / g to 1.6 dl / g (measured as a 0.5% by weight solution in toluene at 30°C).

[0024] These types of polysulfone compositions are commercially available. For example, but not limited to, commercially available STADISTM antistatic agents can be selected, with STADISTM 450 or STADISTM 425 being more preferred. There is no specific limit to the amount of antistatic agent added; the minimum should be sufficient to maintain normal production operations by effectively preventing polymer powder agglomeration and ensuring antistatic properties within the reactor. Since antistatic agents can inhibit catalyst polymerization activity, the actual amount added should be slightly higher than the minimum, for example, 5-10% higher, but not too high. Generally, in fumed polyethylene processes, depending on the equipment process conditions and polymer product performance differences, the amount of antistatic agent injected is generally controlled between 0.001% and 0.05% (wt) of the reactants.

[0025] The polysulfone composition of the present invention preferably comprises 5-70% polysulfone copolymer, 5-70% polymeric polyamine and 5-70% oil-soluble sulfonic acid by weight percentage, with the total of the three components being 100%.

[0026] The polymeric polyamines described in this invention are preferably products of the reaction of N-aliphatic hydrocarbon alkylene diamines or aliphatic primary amines containing at least 8 carbon atoms, and more preferably at least 12 carbon atoms, with epichlorohydrin. Examples of these aliphatic primary amines are those derived from tall oil, beef tallow, soybean oil, coconut oil, and cottonseed oil. Polymeric polyamines derived from the reaction of tallowamine with epichlorohydrin are preferred.

[0027] The oil-soluble sulfonic acid described in this invention is preferably dodecylbenzenesulfonic acid and dinonylnaphthalenesulfonic acid.

[0028] Preferably, the gas-phase polymerization temperature is 45-70°C, and the reaction gases include ethylene, α-olefin, and hydrogen in a molar ratio of 1:0.1-0.5:0.05-0.3, the partial pressure of ethylene is 0.3-0.6 MPa, and the α-olefin includes at least one of 1-butene, 1-hexene, and 1-octene.

[0029] More preferably, the gas-phase polymerization temperature is 50-60℃.

[0030] In gas-phase polymerization, provided the powder does not clump or scale, a higher polymerization temperature results in a stronger heat dissipation capacity of the polymerization reaction system. However, excessively high polymerization temperatures can lead to polymer powder particle agglomeration. Conversely, excessively low polymerization temperatures reduce equipment yield and catalyst polymerization activity. Therefore, the suitable polymerization temperature for the polyolefin elastomer preparation method described in this invention is 45-70°C, more preferably 50-60°C.

[0031] The method for preparing polyolefin elastomers described in this invention can further introduce a small amount of alkyl aluminum or alkyl aluminum oxane cocatalysts into the polymerization reaction system. However, it should be noted that the metallocene catalysts described in this invention already include organoboron compound cocatalysts. The alkyl aluminum or alkyl aluminum oxane introduced into the polymerization reaction system mainly serves to remove water and other impurities from the reaction system.

[0032] The method for preparing polyolefin elastomers described in this invention has the advantages of less agglomeration and clumping caused by static electricity during the production process, good polymer particle morphology, low volatile content, stable production process operation, no need for co-catalysts such as MAO, high catalyst polymerization activity, and low production cost. Attached Figure Description

[0033] Figure 1 Here is a scanning electron microscope image of the solid particles of the metallocene catalyst in Example 1; Figure 2 The image shows a scanning electron microscope (SEM) image of the solid particles of the metallocene catalyst in Comparative Example 1. Figure 3 This is a scanning electron microscope image of the polymer powder from Example 1. Detailed Implementation

[0034] To make the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings.

[0035] The testing methods for each embodiment are as follows: (1) The melt index (MI) of the polymer was tested at 190℃ and 2.16kg load according to the test standard GB / T3682.1-2018.

[0036] (2) The bulk density (BD) of the polymer powder was tested according to the method specified in the test standard GB / T 1636-2008.

[0037] (3) Polymer powder sieving shall be performed in accordance with the test method specified in test standard GB / T 6003.1—2022.

[0038] (4) The polymer density was tested using a densitometer (impregnation method METTLER).

[0039] Synthesis of metallocene compounds in Examples 1-5 (1H NMR measurements were performed using a Bruker Ascend 400M nuclear magnetic resonance spectrometer): The structural formula of the metallocene compound is: .

[0040] Step 1-1: Synthesis of 4-(6-(dichloro(methyl)silyl)hexyl)-N,N-dimethylaniline In a flask, 4-(6-bromohexyl)-N,N-dimethylaniline (5.00 g, 25 mmol) and Mg (1.22 g, 50.2 mmol) were added to THF (25 mL), and the mixture was stirred at 70 °C for 4 hours. In another flask, MeSiCl3 (7.47 g, 50.0 mmol) was dissolved in THF (75 mL), and the mixture was slowly added dropwise at 0 °C for 1 hour. The mixture was then stirred overnight at room temperature, and saturated NaHCO3 was added. Water was removed with anhydrous MgSO4, and the resulting solution was concentrated under reduced pressure to obtain a white solid, 4-(6-(dichloro(methyl)silyl)hexyl)-N,N-dimethylaniline (4.80 g, 82%). The 1H NMR is as follows: 1H NMR (500MHz, CDCl3,7.24ppm): 0.99(3H,s),3.01(6H,s),6.75(2H,d),7.57(2H,d) Steps 1-2: Synthesis of 4-(6-(bis(4-(4-(tert-butyl)phenyl)-2-methyl-1H-inden-1-yl)(methyl)silyl)hexyl)-N,N-dimethylaniline 4-(4-(tert-butyl)phenyl)-2-methyl-1H-indene (10.3 g, 39.3 mmol) and CuCN (176 mg, 1.97 mmol) were dissolved in toluene (90 mL) and THF (12 mL) under argon (Ar) atmosphere. The solution was cooled to -30 °C, and n-butyllithium (2.5 M hexane solution, 16.5 mL) was slowly added. The mixture was stirred at this temperature for about 10 minutes, and then heated to room temperature for 2 hours. The resulting 4-(6-(dichloro(methyl)silyl)hexyl)-N,N-dimethylaniline (4.80 g, 20.5 mmol) in toluene (30 mL) was added to the solution, and the mixture was stirred overnight at room temperature. After the reaction was complete, MTBE and water were added, and the organic layer was separated. The obtained organic layer was dried over anhydrous MgSO4 and concentrated to give 4-(6-(bis(4-(4-(tert-butyl)phenyl)-2-methyl-1H-inden-1-yl)(methyl)silyl)hexyl)-N,N-dimethylaniline (13.8 g, 100%), as a white solid. The 1H NMR is as follows: 1H NMR (500MHz, CDCl3, 7.24ppm): 0.00-0.07(3H,m),1.49-1.52(18H,m),2.46-2.49(6H,m),3.00(3H,s),3.02(3H,s),4.23-4.39(2H,m),6.50-7.52(20H,m) Steps 1-3: Synthesis of [4-(6-(bis(4-(4-(tert-butyl)phenyl)-2-methyl-1H-inden-1-yl)(methyl)silyl)hexyl)-N,N-dimethylaniline]zirconium dichloride Under argon (Ar) atmosphere, 6.74 g (9.83 mmol) of 4-(6-(bis(4-(4-(tert-butyl)phenyl)-2-methyl-1H-inden-1-yl)(methyl)silyl)hexyl)-N,N-dimethylaniline was added to a 50 mL Schlenk flask and dissolved in diethyl ether (8.2 mL). The temperature was lowered to -78 °C, and 8.1 mL (2.5 M in hexane) of n-butyllithium was added, followed by stirring at room temperature for 2 hours. At -78 °C, 2.29 g (9.83 mmol) of ZrCl4 in a Tol / diethyl ether (24.6 mL / 8.2 mL) slurry was slowly added to the ligand solution, the temperature was raised to room temperature, and the mixture was stirred overnight. The solvent was distilled under reduced pressure to dissolve the ligand in CH2Cl2, and the solution was filtered to remove LiCl. The filtrate was concentrated, and the resulting crude product was saturated with CH₂Cl₂. Two volumes of hexane were added, and the mixture was recrystallized at -20°C for 15 hours. Subsequently, when a yellow solid formed, it was filtered and washed twice with hexane to obtain [4-(6-(bis(4-(4-(tert-butyl)phenyl)-2-methyl-1H-inden-1-yl)(methyl)silyl)hexyl)-N,N-dimethylaniline]zirconium dichloride (225 mg, 30%, r / m > 20 / 1). The 1H NMR is as follows: 1H NMR (500MHz, CDCl3, 7.24ppm): 1.30–1.40(21H,m),2.00(3H,s),2.33(3H,s),3.10(6H,s),6.85–7.94(18H,m) Example 1 (1) Catalyst preparation Preparation of metallocene compound solution: Under nitrogen protection, accurately weigh 50g of the synthesized metallocene compound [4-(6-(bis(4-(4-(tert-butyl)phenyl)-2-methyl-1H-inden-1-yl)(methyl)silyl)hexyl)-N,N-dimethylaniline]zirconium dichloride and 300g of N,N-dimethylphenylammonium tetra(perfluorophenyl)borate (commercially available) and transfer them to a glass reactor that has been fully purged with nitrogen. Add 8L of dehydrated and purified tetrahydrofuran, start stirring, heat to 70°C, react for 30min and stir until completely dissolved, then cool to 40°C and wait for the material to dissolve. Preparation of masterbatch to be sprayed: Accurately weigh 1 kg of fumigated silica gel TS-610, transfer it to a glass reactor, and fully replace the air carried in the system with nitrogen; transfer the previously obtained solution to the glass reactor and stir and mix it with the fumigated silica gel for 30 min to obtain the masterbatch to be sprayed; Spray drying: The masterbatch obtained in the previous step was spray-dried using a spray dryer (OM-TS500) to obtain solid microspheres. The spraying conditions were: carrier gas inlet temperature 155℃, outlet temperature 108℃, masterbatch feed pump opening 35%, and atomizing gas flow rate 6L / h. 1.49 kg of spherical metallocene catalyst particles were collected in the product collection tank. The average particle size D50 was 27.2 μm. The morphology images characterized by scanning electron microscopy are shown below. Figure 1 As shown.

[0041] (2) Aggregation Ethylene, hydrogen, and 1-butene are continuously added to a Ф300 gas-phase fluidized bed reactor according to the partial pressure control target of ethylene:1-butene:hydrogen:nitrogen = 0.55 MPa:0.16 MPa:0.05 MPa:1.09 MPa; the concentration of triethylaluminum in the reactor is controlled at 10 ppm; the yield is set at 30 kg / h; and STADIS is used as the antistatic agent. TM A 425 polysulfone composition was added at 0.02% (wt) of the (ethylene + 1-butene) feed amount; the polymerization temperature was 55℃, the average catalyst residence time was 4 hours, and the total pressure of the reaction system was 1.85 MPa. After the reaction reached steady state, the polymer powder was collected, and the polymerization activity of the catalyst was calculated. The obtained polyethylene powder was vacuum dried at 50℃ for 4 hours, and relevant properties were tested. The polymerization properties are shown in Table 1, the sieving results of the polymer powder are shown in Table 2, and the morphology of the polymer powder is shown in Table 3. Figure 3 As shown.

[0042] Example 2 (1) Catalyst preparation Preparation of metallocene compound solution: Under nitrogen protection, accurately weigh 100g of the synthesized metallocene compound [4-(6-(bis(4-(4-(tert-butyl)phenyl)-2-methyl-1H-inden-1-yl)(methyl)silyl)hexyl)-N,N-dimethylaniline]zirconium dichloride and 300g of N,N-dimethylphenylammonium tetra(perfluorophenyl)borate (commercially available) and transfer them to a glass reactor that has been fully purged with nitrogen. Add 8L of dehydrated and purified tetrahydrofuran, start stirring, heat to 70°C, react for 30min and stir until completely dissolved, then cool to 40°C and wait for the material to dissolve. Preparation of masterbatch to be sprayed: Accurately weigh 1 kg of fumigated silica gel TS-610, transfer it to a glass reactor, and fully replace the air carried in the system with nitrogen; transfer the previously obtained solution to the glass reactor and stir and mix it with the fumigated silica gel for 30 min to obtain the masterbatch to be sprayed; Spray drying: The masterbatch obtained in the previous step was spray dried using a spray dryer (OM-TS500) to obtain solid microsphere particles. The spraying conditions were: carrier gas inlet temperature 160℃, outlet temperature 108℃, masterbatch feed pump opening 35%, and atomizing gas flow rate 7L / h. 1.32kg of spherical metallocene catalyst particles were collected in the product collection tank, with an average particle size D50 of 25.9μm.

[0043] (2) Aggregation Same as Example 1.

[0044] Example 3 (1) Catalyst preparation Same as Example 1.

[0045] (2) Aggregation Ethylene, hydrogen, and 1-butene are continuously added to a Ф300 gas-phase fluidized bed reactor according to the partial pressure control target of ethylene:1-butene:hydrogen:nitrogen = 0.55 MPa:0.10 MPa:0.07 MPa:1.1 MPa; the triethylaluminum concentration in the reactor is controlled at 10 ppm; the yield is set at 30 kg / h; and STADIS is used as the antistatic agent. TM A 425 polysulfone composition was added at 0.01% (wt) of the (ethylene + 1-butene) feed amount; the polymerization temperature was 58℃, the average catalyst residence time was 4 hours, and the total pressure of the reaction system was 1.85 MPa. After the reaction reached steady state, the polymer powder was collected, and the polymerization activity of the catalyst was calculated. The obtained polyethylene powder was vacuum dried at 50℃ for 4 hours, and its relevant properties were tested. The polymerization properties are shown in Table 1, and the sieving results of the polymer powder are shown in Table 2.

[0046] Example 4 (1) Catalyst preparation Same as Example 1.

[0047] (2) Aggregation Ethylene, hydrogen, and 1-butene are continuously added to a Ф300 gas-phase fluidized bed reactor according to the partial pressure control target of ethylene:1-butene:hydrogen:nitrogen = 0.55 MPa:0.15 MPa:0.09 MPa:1.09 MPa; the concentration of triethylaluminum in the reactor is controlled at 10 ppm; the yield is set at 30 kg / h; and STADIS is used as the antistatic agent. TM A 425 polysulfone composition was added at 0.05% (wt) of the (ethylene + 1-butene) feed amount; the polymerization temperature was 60℃, the average catalyst residence time was 4 hours, and the total pressure of the reaction system was 1.85 MPa. After the reaction reached steady state, the polymer powder was collected, and the polymerization activity of the catalyst was calculated. The obtained polyethylene powder was vacuum dried at 50℃ for 4 hours, and its relevant properties were tested. The polymerization properties are shown in Table 1, and the sieving results of the polymer powder are shown in Table 2.

[0048] Example 5 (1) Catalyst preparation Same as Example 1.

[0049] (2) Aggregation Ethylene, hydrogen, and 1-hexene were continuously added to a Ф300 gas-phase fluidized bed reactor according to the partial pressure control target of ethylene:1-hexene:hydrogen:nitrogen = 0.55 MPa:0.12 MPa:0.05 MPa:1.09 MPa; the triethylaluminum concentration in the reactor was controlled at 10 ppm; the yield was set at 30 kg / h; and STADIS was used as the antistatic agent. TM A 425 polysulfone composition was added at 0.03% (wt) of the (ethylene + 1-butene) feed amount; the polymerization temperature was 50℃, the average catalyst residence time was 4 hours, and the total pressure of the reaction system was 1.85 MPa. After the reaction reached steady state, the polymer powder was collected, and the polymerization activity of the catalyst was calculated. The obtained polyethylene powder was vacuum dried at 50℃ for 4 hours, and its relevant properties were tested. The polymerization properties are shown in Table 1, and the sieving results of the polymer powder are shown in Table 2.

[0050] Comparative Example 1 (1) Catalyst preparation Preparation of metallocene compound solution: except for the absence of N,N-dimethylphenylammonium tetra(perfluorophenyl)borate, the preparation is the same as in Example 1.

[0051] Preparation of masterbatch to be sprayed: Accurately weigh 1 kg of fumigated silica gel TS-610, transfer it to a glass reactor, and fully replace the air carried in the system with nitrogen; transfer the previously obtained solution to the glass reactor and stir and mix it with the fumigated silica gel for 30 min to obtain the masterbatch to be sprayed; Spray drying: The masterbatch obtained in the previous step was spray-dried using a spray dryer (OM-TS500) to obtain solid microspheres. The spraying conditions were: carrier gas inlet temperature 155℃, outlet temperature 108℃, masterbatch feed pump opening 35%, and atomizing gas flow rate 6L / h. Only 0.36kg of solid product was collected in the product collection tank, and it was in an amorphous state. Its morphology as characterized by scanning electron microscopy is shown in the image below. Figure 3 As shown, this indicates that atomized droplets are unlikely to form high-strength spherical particles during the drying process.

[0052] Comparative Example 2 (1) Catalyst preparation Except for replacing 50g of zirconium dichlorodichloro with the metallocene compound [4-(6-(bis(4-(4-(tert-butyl)phenyl)-2-methyl-1H-indene-1-yl)(methyl)silyl)hexyl)-N,N-dimethylaniline]zirconium dichloride of the present invention, the rest is the same as in Example 1.

[0053] (2) Aggregation Same as Example 1.

[0054] Comparative Example 3 (1) Catalyst preparation Same as Example 1.

[0055] (2) Aggregation Except for the absence of an antistatic agent, everything else is the same as in Example 1.

[0056] Comparative Example 4 (1) Catalyst preparation Under nitrogen protection, accurately weigh 1 kg of pretreated silica gel carrier (Grace955) and transfer it to a glass reactor that has been fully purged with nitrogen. Add 10 L of dehydrated and purified toluene. Stir to disperse it evenly, then add 2 L of methylaluminoxane (1.5 M toluene solution) and stir at 30 °C for 20 min to obtain chemically activated silica gel carrier.

[0057] Under nitrogen protection, 50 g of the synthesized metallocene compound [4-(6-(bis(4-(4-(tert-butyl)phenyl)-2-methyl-1H-inden-1-yl)(methyl)silyl)hexyl)-N,N-dimethylaniline]zirconium dichloride was accurately weighed and added to a chemically activated silica gel / toluene suspension. The mixture was stirred at 30 °C for 60 min. After the reaction was completed, the mixture was allowed to stand for 30 min, and after separation, the liquid was filtered off. The liquid was washed twice with 10 L / time of dehydrated toluene and then twice with 10 L / time of dehydrated hexane. The obtained solid was dried under vacuum at room temperature for 2 hours to obtain the supported metallocene catalyst.

[0058] (2) Aggregation Ethylene, hydrogen, and 1-butene were continuously added to a Ф300 gas-phase fluidized bed reactor according to the partial pressure control target of ethylene:1-butene:hydrogen:nitrogen = 0.55 MPa:0.16 MPa:0.05 MPa:1.09 MPa. The triethylaluminum concentration in the reactor was controlled at 10 ppm. The feed rate of the co-catalyst N,N-dimethylphenylammonium tetra(perfluorophenyl)borate was correlated with the solid particle rate of the metallocene catalyst and the same as the mass feed rate, with a yield set at 30 kg / h. The antistatic agent was STADISTM425 polysulfone composition, added at 0.02 wt% of the (ethylene + 1-butene) feed amount. The polymerization temperature was 55 °C, the average residence time of the catalyst was 4 hours, and the total pressure of the reaction system was 1.85 MPa. After the reaction reached steady state, the polymer powder was collected, and the polymerization activity of the catalyst was calculated. The obtained polyethylene powder was vacuum dried at 50 °C for 4 hours, and the relevant properties were tested. The test results are shown in Table 1.

[0059] Table 1

[0060] Table 2 Polymer Powder Sieving

[0061] The method for preparing polyolefin elastomers of the present invention does not require the use of expensive co-catalysts such as MAO or MMAO. As can be seen from the polymerization data in Table 1, the metallocene catalyst system involved in the present invention exhibits good copolymerization performance and can prepare ethylene / α-olefin random copolymers (POE) under gas-phase polymerization conditions. Furthermore, the consumption of organoborides as co-catalysts is low, and the polymer powder has a good morphology. As can be seen from Table 2, the method for preparing ethylene / α-olefin random copolymers (POE) of the present invention results in less agglomeration and clumping of polymer powder due to electrostatics, good particle morphology, and stable production process, indicating that it has good application prospects in the preparation of polyolefin elastomers, especially ethylene / α-olefin random copolymers (POE).

Claims

1. A method for preparing a polyolefin elastomer, characterized in that, The metallocene catalyst is obtained by gas-phase polymerization of ethylene and α-olefins under the action of metallocene catalyst solid particles and an antistatic agent. The metallocene catalyst solid particles are prepared by spray drying using components comprising metallocene compounds, organoboron compounds, and silica gel. The structural formula of the metallocene compounds is shown in Formula 1. Formula 1; In Formula 1, n is a natural number from 4 to 10; R1 and R2 may be the same or different, and each is independently an aryl group having 6 to 20 carbon atoms or an aryl group having 6 to 20 carbon atoms substituted with an alkyl group having 1 to 20 carbon atoms; R3 is an alkyl group having 1 to 20 carbon atoms; R4 is a tertiary amine having an alkyl group having 1 to 10 carbon atoms; A is carbon, silicon, or germanium; the two Xs may be the same or different, and each is independently a halogen or an alkyl group having 1 to 20 carbon atoms. The organoboron compound is N,N-dimethylphenylammonium tetra(perfluorophenyl)borate; The silica gel is a fumigated silica gel with an average particle size of less than 1 μm.

2. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, The metallocene compounds include one or more of the following structural formulas: Formula 2; Formula 3; Equation 4; Formula 5; Formula 6; Formula 7.

3. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, The solid particles of the metallocene catalyst contain 0.2-10% metallocene compound, 5-50% organoboron compound, and 20-80% silica gel by mass percentage, with an average particle size of 5-100 μm.

4. The method for preparing the polyolefin elastomer according to claim 1 or 3, characterized in that, The metallocene catalyst solid particles comprise, by mass percentage, 0.5-5% metallocene compounds, 20-40% organoboron compounds, and 30-60% silica gel, with an average particle size of 10-60 μm.

5. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, The method for preparing the metallocene catalyst solid particles includes the following steps: Step a): The metallocene compound of Formula 1 and N,N-dimethylphenylammonium tetra(perfluorophenyl)borate are completely dissolved in an inert organic solvent to obtain a homogeneous liquid. The silica gel is then mixed with the above liquid to obtain the masterbatch to be sprayed. Step b): The masterbatch obtained in step a) is spray-dried to obtain spherical metallocene catalyst particles.

6. The method for preparing the polyolefin elastomer according to claim 5, characterized in that, Step a) specifically involves: adding the metallocene compound and N,N-dimethylphenylammonium tetra(perfluorophenyl)borate to tetrahydrofuran, heating to 50°C-reflux temperature, stirring and dissolving for 0.5-10 hours, and after complete dissolution, adjusting the solution temperature to 20-50°C, adding silica gel, and stirring to mix evenly to obtain the masterbatch to be sprayed; the mass ratio of metallocene compound, organoboron compound, tetrahydrofuran, and silica gel is 0.2-10:5-50:200-1000:20-80.

7. The method for preparing the polyolefin elastomer according to claim 5, characterized in that, Metallocene compounds and N,N-dimethylphenylammonium tetra(perfluorophenyl)borate are added to tetrahydrofuran, heated to 60°C-reflux temperature, and stirred for 0.5-10 hours to dissolve. After complete dissolution, the temperature is adjusted to 30-45°C, silica gel is added, and the mixture is stirred and mixed evenly to obtain the masterbatch to be sprayed. The mass ratio of metallocene compounds, organoboron compounds, tetrahydrofuran, and silica gel is 0.5-5:20-40:300-500:30-50.

8. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, The antistatic agent is a polysulfone composition.

9. The method for preparing the polyolefin elastomer according to claim 1, characterized in that, The temperature of gas-phase polymerization is 45-70℃, and the reaction gases include ethylene, α-olefin, and hydrogen in a molar ratio of 1:0.1-0.5:0.05-0.

3. The partial pressure of ethylene is 0.3-0.6 MPa, and the α-olefin includes at least one of 1-butene, 1-hexene, and 1-octene.

10. The method for preparing the polyolefin elastomer according to claim 9, characterized in that, The vapor-phase polymerization temperature is 50-60℃.

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