Dynamic cross-linked polyolefin elastomer and preparation method thereof

Abstract

The invention provides a dynamic cross-linked polyolefin elastomer and a preparation method thereof. According to the method, a double-kettle serial solution polymerization process is adopted, a reaction material is generated through a polymerization reaction in a first reaction kettle, the reaction material is transferred into a second reaction kettle added with a dynamic cross-linking agent and an initiator for continuous reaction and then enters a devolatilization system, a quenching agent is added through a static mixer, then granulation is performed through a screw extruder, and the dynamic cross-linked polyolefin elastomer is obtained. According to the preparation method, dynamic chemical crosslinking is carried out in the production process of the polyolefin elastomer, and the mechanical property and thermal stability of the obtained polyolefin elastomer product can be improved on the premise of ensuring the processability.

Description

Technical Field

[0001] The present invention belongs to the field of polyolefin materials and relates to a dynamically crosslinked polyolefin elastomer and a preparation method thereof. Background Art

[0002] Polyolefin elastomers are a class of high-performance polyolefin materials copolymerized from ethylene and α-olefins (mainly 1-butene, 1-octene, etc.). They have excellent weather resistance, chemical resistance, water vapor resistance, etc., and are widely used in fields such as automobiles, cables, and photovoltaic encapsulation. Traditional polyolefin elastomers such as EPR and EPDM need to undergo an irreversible chemical crosslinking process similar to that of rubber using peroxides or sulfur, which not only makes processing difficult after curing but also makes it difficult to recycle the products at the end of their service life.

[0003] In order to further improve the comprehensive performance of polyolefin elastomers, the prior art has proposed introducing dynamic covalent chemical crosslinking. Dynamic crosslinking can dissociate or exchange under external stimuli, making the material fluid, thereby improving mechanical and thermal properties without sacrificing processing performance. At the same time, physical crosslinking or crystallization in POE is expected to regulate the exchange reaction between dynamic crosslinking agents and improve the stability of the polymer at room temperature, solving the key problems in the practical application of dynamically crosslinked polymers.

[0004] Patent CN117866243A discloses a complex-structured dynamically crosslinked polyolefin elastomer, a preparation method, and an application. This invention obtains a complex-structured dynamically crosslinked polyolefin elastomer by uniformly mixing and reacting a polyolefin elastomer containing carbon-carbon double bonds, a terminal vinyl polyolefin, and a dynamic chemical crosslinking agent containing phenyl borate ester and double-terminal mercapto groups, endowing the elastomer product with excellent tensile strength, tensile toughness, elastic recovery ability, heat resistance, and solvent resistance, and at the same time having good reshaping and reprocessing performance. However, this invention still has the problem of further optimizing the method of synergistic dynamic chemical crosslinking and physical crystallization to improve the efficiency and quality of preparing complex-structured dynamically crosslinked polyolefin elastomers.

[0005] Patent CN115010840A discloses a preparation method of polyolefin elastomers. By adopting a specific feeding method, part of the ethylene monomer, α-olefin, solvent, and cocatalyst are first mixed in a static mixer and then enter the polymerization reactor together with the catalyst, increasing the mass transfer time, making the ethylene disperse evenly and improving the impurity removal effect, thereby improving the catalyst activity. However, this invention still has the problem of optimizing the ratio of the main catalyst and the cocatalyst to improve the polymerization activity and product quality of polyolefin elastomers.

[0006] Generally speaking, in the prior art, there are problems such as the failure to effectively combine the preparation of dynamically crosslinked polyolefin elastomers with the polymerization end, complex preparation processes, poor product property regulation ability, the need to optimize the method of synergistic dynamic chemical crosslinking and physical crystallization, and the need to optimize the ratio of the main catalyst and the co-catalyst. Summary of the Invention

[0007] The object of the present invention is to provide a dynamically crosslinked polyolefin elastomer and a preparation method thereof. This method adopts a two-reactor tandem solution polymerization process. In the first reactor, a polymerization reaction generates reaction materials, which are transferred to the second reactor added with a dynamic crosslinking agent and an initiator for continuous reaction, then enter the devolatilization system, a quenching agent is added through a static mixer, and then granulation is carried out by a screw extruder to obtain the dynamically crosslinked polyolefin elastomer. The present invention combines the preparation of the dynamically crosslinked polyolefin elastomer with the polymerization end, overcomes the deficiencies of the traditional process, and by introducing a dynamic chemical crosslinking agent and an initiator, while ensuring processability, improves the mechanical properties, solvent resistance and heat resistance of the material, thereby expanding the application field of polyolefin elastomers.

[0008] To achieve the above invention object, the present invention adopts the following technical solutions:

[0009] A preparation method of a dynamically crosslinked polyolefin elastomer, comprising the following steps:

[0010] a) In the first reactor, ethylene, α-olefin, copolymerization catalyst, and co-catalyst are introduced, and a polymerization reaction is carried out in a solvent to obtain reaction material R1;

[0011] b) The reaction material R1 obtained in step a) is transferred to the second reactor, and a dynamic chemical crosslinking agent and an initiator are introduced for continuous reaction to obtain reaction material R2;

[0012] c) The reaction material R2 obtained in step b) is devolatilized, and a quenching agent is added;

[0013] d) The material obtained in step c) is introduced into a screw extruder for granulation to obtain the dynamically crosslinked polyolefin elastomer.

[0014] In one embodiment of the present invention, the α-olefin is selected from α-olefins of C4-C10, preferably one or more of 1-hexene, 1-octene, and 1-butene.

[0015] In one embodiment of the present invention, the copolymerization catalyst is a single-site metallocene catalyst and / or a non-metallocene single-site catalyst, preferably one or more selected from titanium, zirconium, and hafnium-based metallocene catalysts and / or non-metallocene single-site catalysts, more preferably one or more of rac-dimethylsilylbis(2-methyl-1-indenyl)zirconium dichloride, diphenylmethylene cyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconium dichloride, di-p-tolylmethylene cyclopentadiene(2,7-di-tert-butyl-fluorenyl)zirconium dichloride, diphenylmethylene(cyclopentadiene)(9-fluorenyl)zirconium dichloride, dimethyldimethylsilylbis(2-methyl-4-phenyl-1-indenyl)zirconium dichloride), (bis(methylcyclopentadiene)zirconium dichloride), (bis(1,3-dimethylcyclopentadienyl)zirconium dichloride, (cyclopentadienyl)(1,2-dimethoxyethane)zirconium trichloride, diphenylsilyl(cyclopentadiene)(9-fluorenyl)zirconium dichloride, meso-dimethylsilylbis(1-indenyl)zirconium dichloride, dimethylsilyl(N-tert-butylamido)(tetramethylcyclopentadienyl)titanium dichloride, dimethylsilyl(N-tert-butylamido)(tetramethylcyclopentadienyl)dimethyltitanium, dimethylsilyl(N-tert-butylamido)(fluorenyl)titanium dichloride, (pentamethylcyclopentadienyl)trimethoxytitanium, dimethylbis(propylcyclopentadienyl)hafnium, bis(n-butylcyclopentadiene)hafnium dichloride.

[0016] In one embodiment of the present invention, the cocatalyst includes one or more of alkylaluminum, alkylaluminoxane, and organic boron compounds, preferably one or more of methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, tris(pentafluorophenyl)borate compound, and tetrakis(pentafluorophenyl)borate compound (such as triphenylcarbenium tetrakis(pentafluorophenyl)borate).

[0017] In one embodiment of the present invention, the solvent is selected from aliphatic hydrocarbon solvents and / or aromatic hydrocarbon solvents, preferably C2-C9 aliphatic hydrocarbon solvents and / or aromatic hydrocarbon solvents; more preferably, the aliphatic hydrocarbon solvents are selected from one or more of Isopar E, n-hexane, methylcyclohexane, cyclohexane, n-butane, isobutane, n-pentane, cyclopentane, methylcyclopentane, methylenecyclopentane, ethylcyclohexane, n-heptane, n-octane, and n-nonane; more preferably, the aromatic hydrocarbon solvents are selected from one or more of benzene, toluene, xylene, monochlorobenzene, dichlorobenzene, trichlorobenzene, and dichlorotoluene.

[0018] In one embodiment of the present invention, in step a), when the cocatalyst contains aluminum, the molar ratio of the metal atom in the copolymerization catalyst to aluminum in the copolymerization cocatalyst is 1:(50-1000).

[0019] In one embodiment of the present invention, in step a), when the cocatalyst contains boron, the molar ratio of the metal atom in the copolymerization catalyst to boron in the cocatalyst is 1:(1 - 5).

[0020] In one embodiment of the present invention, the reaction temperature in the first reaction kettle is 90°C - 230°C, the reaction time is 5 - 18 min; the pressure of ethylene is 1 MPa - 6 MPa.

[0021] In one embodiment of the present invention, the reaction temperature in the second reaction kettle is 110°C - 180°C, and the reaction time is 3 - 12 min.

[0022] In one embodiment of the present invention, in step b), the dynamic chemical crosslinking agent is selected from 2,2'-(1,4-phenylene)-bis[4-mercapto-1,3,2-dioxaborolane].

[0023] In one embodiment of the present invention, in step b), the initiator is selected from one or more of azobiscyclohexanecarbonitrile, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dicumyl peroxide, bis(tert-butylperoxy)diisopropylbenzene, tert-butyl peroxy-2-ethylhexyl carbonate, tert-butyl 2-ethylhexyl carbonate (TBEC), tert-amyl peroxy(2-ethylhexyl) carbonate (TAEC).

[0024] In one embodiment of the present invention, in step c), a quenching agent is added to terminate the reaction. Preferably, the amount of the quenching agent is 0.5 - 5 times, preferably 1 - 3 times, the amount of substance of the cocatalyst.

[0025] In one embodiment of the present invention, the quenching agent is selected from one or more of water, ethanol, ethylene glycol, n-propanol, glycerol, n-butanol, 2-butanol, neopentyl alcohol, 1,6-hexanediol, n-octanol, 2-ethylhexanol, benzyl alcohol, n-decanol, dodecanol, tetradecanol, hexadecanol, and more preferably one or more of water, ethanol, 2-ethylhexanol, tetradecanol, and hexadecanol.

[0026] In one embodiment of the present invention, in step c), the quenching agent is added through a static mixer.

[0027] In one embodiment of the present invention, in step c), the devolatilization includes flash evaporation and static devolatilization.

[0028] In one embodiment of the present invention, in step c), the flash evaporation temperature is 170 - 230°C, and the pressure is 0.5 - 3.5 Mpa.

[0029] In one embodiment of the present invention, in step c), the static devolatilization temperature is 150 - 250 °C, and the pressure is -0.5 to 0.1 Mpa.

[0030] In one embodiment of the present invention, in step d), the residence time of the material in the screw extruder is 1 - 8 min, preferably 1 - 5 min.

[0031] In the present invention, unless otherwise specified, the pressures involved are gauge pressures.

[0032] A dynamically crosslinked polyolefin elastomer, characterized in that the melting point is 55 - 90 °C, the elongation at break is ≥ 900%, the elastic recovery is ≥ 50%, and the gel content is ≤ 2.0 wt%.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) In the present invention, in the twin - kettle series solution polymerization process, by adding an initiator and a dynamic chemical crosslinking agent, and then pelletizing with a screw extruder, a dynamically crosslinked polyolefin elastomer is obtained. Combining the preparation of the dynamically crosslinked polyolefin elastomer with the polymerization end improves the product performance and reduces the production cost.

[0035] (2) The preparation process of the present invention is simple, and the product performance can be adjusted by simply changing the addition amount and type of the initiator and the dynamic chemical crosslinking agent, which is beneficial to industrial production.

[0036] (3) The crosslinking performance of the prepared dynamically crosslinked polyolefin elastomer is controllable, and it has excellent tensile strength, tensile toughness and elastic recovery ability, and can endow the product with good re - processing performance. Detailed implementation mode

[0037] The following specific examples only illustrate the present invention, but these examples are only part of the content of the present invention and do not limit the application of the present invention in other fields. The raw materials used in the examples are all conventional raw materials in the art, and the purity specifications used are analytical pure or chemically pure.

[0038] Raw material source information:

[0039] 1 - octene: 98%, Chevron Corporation

[0040] 1 - hexene: ≥ 97%, Chevron Corporation

[0041] 1 - butene: ≥ 97%, self - supplied from Wanhua Chemical plant

[0042] Isopar E: ExxonMobil Corporation

[0043] Azodicyclohexanecarbonitrile: 98%, Sigma - Aldrich (Shanghai) Trading Co., Ltd.

[0044] tert-Amyl peroxy(2-ethylhexyl) carbonate: >95%, Lanzhou Auxiliary Chemical Factory Co., Ltd.

[0045] tert-Butyl peroxy(2-ethylhexyl) carbonate: >95%, Lanzhou Auxiliary Chemical Factory Co., Ltd.

[0046] 2,2'-(1,4-Phenylene)-bis[4-mercapto-1,3,2-dioxaborolane]: 98%, Shanghai Bide Pharmatech Co., Ltd.

[0047] Dibenzylidene(cyclopentadienyl)(9-fluorenyl)zirconium dichloride: 97%, Anhui Dunmao New Materials Technology Co., Ltd.

[0048] Dibenzylidenecyclopentadienyl(2,7-di-tert-butyl-fluorenyl)zirconium dichloride: 97%, Anhui Dunmao New Materials Technology Co., Ltd.

[0049] Dimethylsilyl(N-tert-butylamido)(tetramethylcyclopentadienyl)dimethyltitanium: 97%, Jiangsu Syncol Catalyst Co., Ltd.

[0050] Dimethylsilyl(N-tert-butylamido)(tetramethylcyclopentadienyl)dimethyltitanium: 97%, Jiangsu Syncol Catalyst Co., Ltd.

[0051] Water: Deionized water, self-made in the laboratory

[0052] Ethanol: Analytically pure, Sinopharm Chemical Reagent Co., Ltd.

[0053] MMAO-7 (Modified methylaluminoxane): 7 wt% Al concentration, Isopar E solvent, Nouryon Chemicals (Ningbo) Co., Ltd.

[0054] [Ph3C][B(C6F5)4]: Triphenylcarbenium tetrakis(pentafluorophenyl)borate, >97%, Jiangsu Syncol Catalyst Co., Ltd.

[0055] Melting point test: The melting point (Tm) of the polymerization product was characterized using a DSC analyzer. The instrument model used was Mettle DSC1. Weigh about 5 mg of the sample into an aluminum sample pan, cover and seal it. Use tweezers to place the prepared sample into the sample cell and cover the furnace lid. Enter the sample mass in the control software. The heating program first heats from 40 °C to 160 °C at a heating rate of 10 °C / min, and holds at 160 °C for 5 min to eliminate the thermal history. Then cool to 40 °C at a cooling rate of 10 °C / min and collect the crystallization curve of the sample. Finally, heat to 160 °C at a heating rate of 10 °C / min again and collect the heat fusion curve of the sample, recording the enthalpy change and melting point during this process.

[0056] The tensile property test was carried out according to ASTM-D412 standard using a universal testing machine (Instron 5967). The testing machine was equipped with a 500N load cell and mechanical clamps. The test temperature was 25°C or 140°C, and the moving speed of the upper crossbeam was 50 mm / min.

[0057] The reprocessing procedure was to cut the material into small pieces less than 1 cm and then hot press at 160°C for 1 hour. The reprocessing efficiency = (tensile toughness after reprocessing / tensile toughness before reprocessing) × 100%.

[0058] In the elastic recovery test, the material was stretched at a speed of 20 mm / min to an elongation of 250% and stretched 10 times. The elastic recovery rate = (250 - residual elongation) / 250 × 100%.

[0059] The gel content was determined by Soxhlet extraction experiment. At room temperature, a dry sample obtained by cross-linking a tablet with a mass of M0 was extracted under toluene reflux at 120°C for 8 hours, and then the residual insoluble sample was dried in a vacuum oven at 60°C until the weight was constant, and the mass M1 was recorded at this time. Three samples were measured for each sample. The gel content = (M0 - M1) / M0.

[0060] Example 1

[0061] A preparation method of a dynamically cross-linked polyolefin elastomer. The series-connected double reactors are both 500 mL stainless steel reactors, and the method includes the following steps:

[0062] Ethylene / 1-octene continuous solution polymerization. Under a pressure of 3 Mpa, Isopar E solvent (2169 g / h), 1-octene (583 g / h), ethylene (351 g / h), MMAO-7 (7 wt% Al, 578.5 mg / h) were fed into a 500 ml stirred reactor I preheated to 145°C. The main catalyst dimethylsilyl(N-tert-butylamido)(tetramethylcyclopentadienyl)titanium dichloride (T1) was injected into reactor I alone at 1.105 mg / h. The outlet material of reactor I entered reactor II, and 400 mg / h of azobis(cyclohexanecarbonitrile) and 6 g / h of 2,2'-(1,4-phenylene)-bis[4-mercapto-1,3,2-dioxaborolane] were added at the inlet of reactor II. Reactor II was preheated to 150°C. After completion, the obtained polymer solution entered a flash tank (200°C, 2 Mpa) for flash evaporation for 10 min, and then entered a devolatilization system (200°C, -0.1 MPa) in sequence. 30 mg / h of H2O was added through a static mixer, and finally it was extruded at 190°C through a twin-screw extruder (the residence time of the material was 3 min) to obtain dynamically cross-linked polyolefin elastomer particles. The properties of the polymer are shown in Table 1.

[0063] Example 2

[0064] A preparation method of a dynamically crosslinked polyolefin elastomer. The series-connected double reactors are both 500 mL stainless steel reaction vessels, and the method includes the following steps:

[0065] The continuous solution polymerization conditions of ethylene / 1-octene are as shown in Example 1. The difference is that both Reactor 1 and Reactor 2 are preheated to 130 °C. MMAO-7 (7 wt% Al, 173.6 mg / h) is fed into a 500 ml stirred reactor preheated to 130 °C. The main catalyst dimethylsilyl(N-tert-butylamido)(tetramethylcyclopentadienyl)dimethyltitanium (T2) is separately injected into Reactor 1 at 0.976 mg / h. The material at the outlet of Reactor 1 enters Reactor 2, and 400 mg / h of azobiscyclohexanecarbonitrile and 8 g / h of 2,2'-(1,4-phenylene)-bis[4-mercapto-1,3,2-dioxaborolane] are added at the inlet of Reactor 2. After completion, the obtained polymer solution enters a flash tank (190 °C, 3 Mpa) from the outlet of Reactor 2 for flash evaporation for 10 min, and then enters a devolatilization (220 °C, -0.1 MPa) system in sequence. 6 mg / h of ethanol is added through a static mixer, and finally, it is extruded at 190 °C through a twin-screw extruder (the residence time of the material is 2 min) to obtain dynamically crosslinked polyolefin elastomer particles. The properties of the polymer are shown in Table 1.

[0066] Example 3

[0067] A preparation method of a dynamically crosslinked polyolefin elastomer. The series-connected double reactors are both 500 mL stainless steel reaction vessels, and the method includes the following steps:

[0068] Ethylene / 1-butene continuous solution polymerization, at a pressure of 3 Mpa, methylcyclohexane solvent (2200 g / h), 1-butene (653 g / h), ethylene (351 g / h), MMAO-7 (7 wt% Al, 11.6 mg / h), and triphenylcarbenium tetrakis(pentafluorophenyl)borate (3.32 mg / h) were fed into a 500 ml stirred reactor I preheated to 145°C. The main catalyst, dibenzylidene(cyclopentadienyl)(9-fluorenyl)zirconium dichloride (Z3), was separately injected into reactor I at 1.105 mg / h. The outlet material of reactor I entered reactor II, and 200 mg / h of tert-butyl peroxy-2-ethylhexyl carbonate (TBEC) and 5 g / h of 2,2'-(1,4-phenylene)-bis[4-mercapto-1,3,2-dioxaborolane] were added at the inlet of reactor II. After completion, the obtained polymer solution exited from reactor II and entered a flash tank (200°C, 0.5 Mpa) for flash evaporation for 10 min, and then successively entered a devolatilization system (200°C, -0.5 MPa). 2.7 mg / h of H2O was added through a static mixer, and finally, it was extruded at 190°C through a twin-screw extruder (material residence time 1.5 min) to obtain dynamic crosslinked polyolefin elastomer particles. The properties of the polymer are shown in Table 1.

[0069] Example 4

[0070] A method for preparing a dynamically crosslinked polyolefin elastomer, where the series-connected double reactors are both 500 mL stainless steel reaction vessels, and it includes the following steps:

[0071] The conditions for ethylene / 1-butene continuous solution polymerization are as shown in Example 3, except that the temperature of reactor I is 155°C, the temperature of reactor II is 160°C, and the main catalyst, dibenzylidene cyclopentadiene (2,7-di-tert-butyl-fluorenyl)zirconium dichloride (Z4), is separately injected into reactor I at 1.320 mg / h. The initiator used is 200 mg / h of tert-amyl peroxy-2-ethylhexyl carbonate (TAEC). Flash evaporation is carried out in a flash tank (200°C, 3 Mpa) for 10 min, and then it successively enters a devolatilization system (220°C, 0.1 MPa). The properties of the polymer are shown in Table 1.

[0072] Example 5

[0073] A method for preparing a dynamically crosslinked polyolefin elastomer, where the series-connected double reactors are both 500 mL stainless steel reaction vessels, and it includes the following steps:

[0074] Ethylene / 1 - hexene continuous solution polymerization. Under a pressure of 5 Mpa, n - hexane solvent (2000 g / h), 1 - hexene (653 g / h), ethylene (351 g / h), and MMAO - 7 (7 wt% Al, 231.4 mg / h) are fed into a 500 - ml stirred reactor I preheated to 145°C. The main catalyst, dibenzylidene(cyclopentadienyl)(9 - fluorenyl)zirconium dichloride (Z3), is injected into reactor I alone at a rate of 1.105 mg / h. The outlet material of reactor I enters reactor II, and 100 mg / h of TCS (50 mg / h each of TBEC and TAEC) and 4 g / h of 2,2’-(1,4 - phenylene)-bis[4 - mercapto - 1,3,2 - dioxaborolane] are added at the inlet of reactor II. Reactor II is preheated to 170°C. After completion, the obtained polymer solution exits from reactor II and enters a flash tank (200°C, 0.5 Mpa) for flashing for 10 min, then successively enters a devolatilization system (220°C, - 0.1 MPa), 32.4 mg / h of H2O is added through a static mixer, and finally, it is extruded at 190°C through a twin - screw extruder (material residence time 3 min) to obtain dynamic cross - linked polyolefin elastomer particles. The properties of the polymer are shown in Table 1.

[0075] Example 6

[0076] A method for preparing a dynamic cross - linked polyolefin elastomer. The series - connected double reactors are both 500 - mL stainless - steel reaction vessels, and the method includes the following steps:

[0077] Ethylene / 1 - octene continuous solution polymerization. Under a pressure of 3 Mpa, Isopar E solvent (2169 g / h), 1 - octene (583 g / h), ethylene (351 g / h), and MMAO - 7 (7 wt% Al, 289.3 mg / h) are fed into a 500 - ml stirred reactor I preheated to 145°C. The main catalyst, dibenzylidene(cyclopentadienyl)(9 - fluorenyl)zirconium dichloride (Z3), is injected into reactor I alone at a rate of 1.105 mg / h. The outlet material of reactor I enters reactor II, and 200 mg / h of azobis(cyclohexanecarbonitrile) and 8 g / h of 2,2’-(1,4 - phenylene)-bis[4 - mercapto - 1,3,2 - dioxaborolane] are added at the inlet of reactor II. Reactor II is preheated to 145°C. After completion, the obtained polymer solution exits from reactor II and enters a flash tank (210°C, 3 Mpa) for flashing for 10 min, then successively enters a devolatilization system (220°C, - 0.1 MPa), 27 mg / h of H2O is added through a static mixer, and finally, it is extruded at 190°C through a twin - screw extruder (material residence time 3 min) to obtain dynamic cross - linked polyolefin elastomer particles. The properties of the polymer are shown in Table 1.

[0078] Example 7

[0079] A preparation method of a dynamically crosslinked polyolefin elastomer. The series-connected double reactors are both 500 mL stainless steel reaction vessels, and the method includes the following steps:

[0080] An ethylene / 1-octene continuous solution. Under a pressure of 3 Mpa, the Isopar E solvent (2169 g / h), 1-octene (583 g / h), ethylene (351 g / h), and MMAO-7 (7 wt% Al, 289.3 mg / h) are fed into a 500 ml stirred reactor one preheated to 140 °C. Reactor two is preheated to 140 °C. The main catalyst dimethylsilyl(N-tert-butylamido)(tetramethylcyclopentadienyl)dimethyltitanium (T2) is separately injected into reactor one at 0.976 mg / h. The material at the outlet of reactor one enters reactor two, and 100 mg / h of azobis(cyclohexanecarbonitrile) and 4 g / h of 2,2'-(1,4-phenylene)-bis[4-mercapto-1,3,2-dioxaborolane] are added at the inlet of reactor two. After completion, the obtained polymer solution enters a flash tank (190 °C, 3 Mpa) from the outlet of reactor two for flash evaporation for 10 min, and then enters a devolatilization (200 °C, -0.1 MPa) system in sequence. 40.5 mg / h of H2O is added through a static mixer, and finally, it is extruded at 190 °C through a twin-screw extruder (the residence time of the material is 2 min) to obtain dynamically crosslinked polyolefin elastomer particles. The properties of the polymer are shown in Table 1.

[0081] Example 8

[0082] A preparation method of a dynamically crosslinked polyolefin elastomer. The series-connected double reactors are both 500 mL stainless steel reaction vessels, and the method includes the following steps:

[0083] Ethylene / 1-butene continuous solution polymerization. Under a pressure of 3 MPa, the Isopar E solvent (2169 g / h), 1-butene (583 g / h), ethylene (351 g / h), and MMAO-7 (7 wt% Al, 289.3 mg / h) are fed into a 500-ml stirred reactor I preheated to 130°C. Reactor II is preheated to 130°C. The main catalyst dimethylsilyl(N-tert-butylamido)(tetramethylcyclopentadienyl)dimethyltitanium (T2) is separately injected into reactor I at a rate of 0.976 mg / h. The material at the outlet of reactor I enters reactor II, and 100 mg / h of azobis(cyclohexanecarbonitrile) and 4 g / h of 2,2'-(1,4-phenylene)-bis[4-mercapto-1,3,2-dioxaborolane] are added at the inlet of reactor II. After completion, the obtained polymer solution enters a flash tank (200°C, 3 MPa) from the reactor outlet for flash evaporation for 10 min, and then successively enters a devolatilization (200°C, -0.1 MPa) system. 40.5 mg / h of H2O is added through a static mixer, and finally, it is extruded at 190°C (material residence time 2 min) through a twin-screw extruder to obtain dynamic crosslinked polyolefin elastomer particles. The properties of the polymer are shown in Table 1.

[0084] Comparative Example 1

[0085] A preparation method of a dynamic crosslinked polyolefin elastomer. The series-connected double reactors are both 500 mL stainless steel reaction kettles, and the method includes the following steps:

[0086] Ethylene / 1-octene continuous solution polymerization. Under a pressure of 3 MPa, the Isopar E solvent (2169 g / h), 1-octene (583 g / h), ethylene (351 g / h), and MMAO-7 (7 wt% Al, 289.3 mg / h) are fed into a 500-ml stirred reactor I preheated to 145°C. The main catalyst dibenzylidene(cyclopentadienyl)(9-fluorenyl)zirconium dichloride (Z3) is separately injected into reactor I at a rate of 1.105 mg / h. The material at the outlet of reactor I enters reactor II, and 200 mg / h of azobis(cyclohexanecarbonitrile) is added at the inlet of reactor II. Reactor II is preheated to 145°C and the reaction continues. After completion, the obtained polymer solution enters a flash tank (210°C, 3 MPa) from the outlet of reactor II for flash evaporation for 10 min, and then successively enters a devolatilization (220°C, -0.1 MPa) system. 27 mg / h of H2O is added through a static mixer, and finally, it is extruded at 190°C (material residence time 3 min) through a twin-screw extruder to obtain dynamic crosslinked polyolefin elastomer particles. The properties of the polymer are shown in Table 1.

[0087] Table 1 Properties of the polymer

[0088]

[0089]

Claims

1. A method for preparing a dynamically cross-linked polyolefin elastomer, comprising the following steps: a) introducing ethylene, α-olefin, copolymerization catalyst and co-catalyst into a first reaction vessel, and carrying out polymerization reaction in a solvent to obtain reaction material R1; b) transferring the reaction material R1 obtained in step a) into a second reaction kettle, introducing a dynamic chemical crosslinking agent and an initiator to continue the reaction, and obtaining the reaction material R2; c) devolatilizing the reaction material R2 obtained in step b) and adding a quenching agent; d) passing the material obtained in step c) into a screw extruder for granulation to obtain a dynamically cross-linked polyolefin elastomer.

2. The method according to claim 1, characterized in that The α-olefin is selected from C4-C10 α-olefins, preferably one or more of 1-hexene, 1-octene, and 1-butene.

3. The method according to claim 1 or 2, characterized in that: The copolymerization catalyst is a metallocene catalyst with a single active center and / or a non-metallocene catalyst with a single active center, preferably one or more of titanium, zirconium, and hafnium metallocene catalysts and / or non-metallocene catalysts with a single active center, more preferably racemic dimethylsilylbis(2-methyl-1-indenyl) zirconium dichloride, diphenylmethylenecyclopentadiene(2,7-di-tert-butyl-fluorenyl) zirconium dichloride, di-p-toluenemethylcyclopentadiene(2,7-di-tert-butyl-fluorenyl) zirconium dichloride, diphenylmethylene(cyclopentadiene)(9-fluorenyl) zirconium dichloride, dimethyldisilylbis(2-methyl-4-phenyl-1-indenyl) zirconium dichloride), (bis(methylcyclopentadiene) dichloride The invention can be selected from the group consisting of (1,3-dimethylcyclopentadienyl) zirconium dichloride, (cyclopentadienyl) (1,2-dimethoxyethane) zirconium trichloride, diphenylsilyl (cyclopentadienyl) (9-fluorenyl) zirconium dichloride, meso-dimethylsilyl bis (1-indenyl) zirconium dichloride, dimethylsilyl (N-tert-butylamino) (tetramethylcyclopentadienyl) titanium dichloride, dimethylsilyl (N-tert-butylamino) (tetramethylcyclopentadienyl) titanium dimethyl, dimethylsilyl (N-tert-butylamino) (fluorenyl) titanium dichloride, (pentamethylcyclopentadienyl) trimethoxytitanium, dimethylbis (propylcyclopentadienyl) hafnium, and bis (n-butylcyclopentadienyl) hafnium dichloride.

4. The method according to any one of claims 1 to 3, characterized in that: The co-catalyst includes one or more of alkylaluminum, alkylaluminoxane, and organic boron compounds, preferably one or more of methylaluminoxane, modified methylaluminoxane, ethylaluminoxane, trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum, tris(pentafluorophenyl)borate compounds, and tetrakis(pentafluorophenyl)borate compounds (such as triphenylcarbon tetrakis(pentafluorophenyl)borate).

5. The method according to any one of claims 1 to 4, characterized in that: In the step a), when the co-catalyst contains aluminum, the molar ratio of the metal atoms in the copolymerization catalyst to the aluminum in the copolymerization co-catalyst is 1:(50-1000); and / or, in the step a), when the co-catalyst contains boron, the molar ratio of the metal atoms in the copolymerization catalyst to the boron in the co-catalyst is 1:(1-5).

6. The method according to any one of claims 1 to 5, characterized in that: The reaction temperature of the first reactor is 90°C-230°C, and the reaction time is 5-18 min; the ethylene pressure is 1 MPa-6 MPa; and / or, the reaction temperature of the second reactor is 110°C-180°C, and the reaction time is 3-12 min.

7. The method according to any one of claims 1 to 6, characterized in that: In the step b), the dynamic chemical cross-linking agent is selected from 2,2'-(1,4-phenylene)-bis[4-mercapto-1,3,2-dioxaborolane].

8. The method according to any one of claims 1 to 7, characterized in that: In the step b), the initiator is selected from one or more of azobiscyclohexylcarbonitrile, 2,5-dimethyl-2,5-bis(tert-butylperoxide)hexane, diisopropylbenzene peroxide, di-tert-butylperoxide diisopropylbenzene, tert-butylperoxy-2-ethylhexylcarbonate, tert-butylperoxy-2-ethylhexylcarbonate (TBEC), and tert-amylperoxy (2-ethylhexyl)carbonate (TAEC).

9. The method according to any one of claims 1 to 8, characterized in that: In the step c), a quencher is added to terminate the reaction. Preferably, the amount of the quencher is 0.5 to 5 times, preferably 1 to 3 times, of the amount of the promoter substance; the quencher is selected from one or more of water, ethanol, ethylene glycol, n-propanol, glycerol, n-butanol, 2-butanol, neopentyl alcohol, 1,6-hexanediol, n-octanol, 2-ethylhexanol, benzyl alcohol, n-decanol, dodecanol, tetradecanol, and hexadecanol.

10. A dynamically cross-linked polyolefin elastomer prepared by the method according to any one of claims 1 to 9, characterized in that: Melting point 55-90℃, elongation at break ≥900%, elastic recovery ≥50%, gel content ≤2.0wt%.

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