Ethylene copolymers, process for their preparation and compositions, crosslinked polymers and tires

Abstract

This invention discloses an ethylene copolymer containing ethylene structural units derived from ethylene, α-olefin structural units derived from α-olefins, and conjugated diene structural units derived from conjugated dienes. The molar ratio of the ethylene structural units to the conjugated diene structural units is 2-10:1. Based on the total amount of the ethylene copolymer, the content of the conjugated diene structural units is 5-20 mol%. The ethylene copolymer also contains anti-1,4-structural units, which are structural units formed by 1,4-polymerization of the conjugated diene and possessing anti-1,4-double bonds. Based on the total amount of the conjugated diene structural units in the ethylene copolymer, the content of the anti-1,4-structural units is 10-50 mol%. The ethylene copolymer according to this invention exhibits good compatibility and co-vulcanization properties. The ethylene copolymer according to this invention has broad application prospects in the rubber industry, particularly in the field of automotive tire rubber.

Description

Technical Field

[0001] This invention relates to an ethylene copolymer, and more specifically, to an ethylene copolymer containing structural units derived from ethylene, α-olefin structural units derived from α-olefins, and conjugated diene structural units derived from conjugated dienes; the invention also relates to a composition containing the ethylene copolymer and a crosslinked polymer containing units derived from the ethylene copolymer; the invention further relates to a tire, wherein at least one constituent element of the tire contains the ethylene copolymer, the composition, or the crosslinked polymer. Background Technology

[0002] Ethylene, as a widely used and readily available monomer, is extensively used in the plastics industry. Conjugated dienes, especially butadiene and isoprene, are the most important monomers for synthetic rubber. Butadiene, as a byproduct of the petroleum-based ethylene production process, was once priced similarly to ethylene. Recently, due to changes in ethylene production routes, butadiene production has decreased, leading to a significant price increase. In contrast, the price of ethylene has decreased. Therefore, using ethylene as a raw material for producing tire rubber is quite attractive, as it can greatly reduce raw material costs.

[0003] However, due to the different polymerization mechanisms of conjugated dienes and α-olefins, copolymerization is difficult. Therefore, catalyzing the copolymerization of ethylene and conjugated dienes using the same catalytic system is an extremely challenging task, and achieving their copolymerization has always been a goal pursued by both academia and industry.

[0004] Ethylene propylene diene monomer (EPDM) rubber is a copolymer of ethylene, propylene, and a third monomer. This third monomer is typically a non-conjugated diene such as ethylene-ide norbornene or dicyclopentadiene, which is more expensive than conjugated dienes such as butadiene and isoprene. Furthermore, EPDM rubber has poor compatibility with diene rubbers such as styrene-butadiene rubber (SBR) and exhibits poor co-curing properties, limiting its application in the tire industry.

[0005] Tan Rui et al. (Tan Rui et al., Study on the Copolymerization of Ethylene, Propylene and Conjugated Dienes Catalyzed by Scandium Monocyclic Catalyst, 2017 National Polymer Academic Paper Conference of the Chinese Chemical Society) used a scandium monocyclic catalyst to copolymerize ethylene, propylene and conjugated dienes, obtaining a random copolymer in which the butadiene unit was predominantly cis-1,4-structured. Compared with ethylene, propylene and conjugated diene terpolymers predominantly cis-1,4-structured, polybutadiene and its copolymers containing trans-1,4-structured units exhibit lower heat of compression, and excellent fatigue resistance, abrasion resistance, and tear resistance. Reports on ethylene, propylene and conjugated diene terpolymers containing trans-1,4-structured units are rare. GB1519472 reports the copolymerization of ethylene, propylene and butadiene using vanadium-based catalysts. The resulting copolymer had an extremely low butadiene insertion rate of less than 2%, existing in the trans-1,4-structured form. The low double bond content in the copolymer results in a slow vulcanization rate. Summary of the Invention

[0006] The purpose of this invention is to provide a terpolymer of ethylene, propylene and conjugated diene containing trans-1,4-structural units.

[0007] According to a first aspect of the present invention, an ethylene copolymer is provided, the ethylene copolymer comprising ethylene structural units derived from ethylene, α-olefin structural units derived from α-olefins, and conjugated diene structural units derived from conjugated dienes, wherein the molar ratio of the ethylene structural units to the conjugated diene structural units is 2-10:1, and the content of the conjugated diene structural units is 5-20 mol% based on the total amount of the ethylene copolymer. The ethylene copolymer also contains trans-1,4-structural units, the trans-1,4-structural units being structural units formed by 1,4-polymerization of the conjugated diene and having trans-1,4-double bonds, and the content of the trans-1,4-structural units is 10-50 mol% based on the total amount of the conjugated diene structural units in the ethylene copolymer.

[0008] According to a second aspect of the present invention, the present invention provides a method for preparing an ethylene copolymer, the method comprising contacting ethylene, α-olefin and conjugated diene with a metallocene catalyst and methylaluminoxane under olefin polymerization conditions, wherein the metallocene catalyst is selected from rac-ethylenebis(1-indenyl)zirconia and diphenylmethylene(cyclopentadienyl)(fluorenyl)zirconia.

[0009] According to a third aspect of the present invention, the present invention provides an ethylene copolymer prepared by the method described in the second aspect of the present invention.

[0010] According to a fourth aspect of the present invention, the present invention provides a composition comprising an ethylene copolymer and a crosslinking agent, wherein the ethylene copolymer is the ethylene copolymer described in the first aspect or the third aspect of the present invention.

[0011] According to a fifth aspect of the present invention, a crosslinked polymer is provided, which is formed by crosslinking an ethylene copolymer described in the first or third aspect of the present invention.

[0012] According to a sixth aspect of the present invention, a tire is provided in which at least one constituent element comprises an ethylene copolymer as described in the first or third aspect of the present invention, a composition as described in the fourth aspect of the present invention, or a crosslinked polymer as described in the fifth aspect of the present invention.

[0013] According to the ethylene copolymer of the present invention, the conjugated diene exists in two forms: 1,4-polymerization and 1,2-polymerization. The structural unit formed by its 1,4-polymerization is mainly composed of inverse 1,4-structural units and contains little or no cis 1,4-structural units.

[0014] The ethylene copolymers according to the present invention exhibit good compatibility and co-vulcanization properties. The ethylene copolymers according to the present invention have broad application prospects in the rubber industry, particularly in the field of automotive tire rubber. Detailed Implementation

[0015] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0016] According to a first aspect of the present invention, an ethylene copolymer is provided, the ethylene copolymer comprising ethylene structural units derived from ethylene, α-olefin structural units derived from α-olefins, and conjugated diene structural units derived from conjugated dienes.

[0017] In this invention, a "structural unit derived from ethylene" refers to a structural unit formed from ethylene, and compared to ethylene, the structural unit has the same atomic types and number of atoms except for a change in electronic structure. A "structural unit derived from a conjugated diene" refers to a structural unit formed from a conjugated diene, and compared to a conjugated diene, the structural unit has the same atomic types and number of atoms except for a change in electronic structure. An "α-olefin structural unit derived from an α-olefin" refers to a structural unit formed from an α-olefin, and compared to an α-olefin, the structural unit has the same atomic types and number of atoms except for a change in electronic structure.

[0018] According to the ethylene copolymer of the present invention, the conjugated diene refers to a compound containing conjugated double bonds in its molecular structure. The conjugated diene may be one or more compounds selected from those shown in Formula 1.

[0019]

[0020] In Formula 1, R1, R2 and R3 may be the same or different, and each is selected from hydrogen and C1-C5 straight-chain or branched alkyl groups.

[0021] According to the ethylene copolymer of the present invention, specific examples of the conjugated diene may include, but are not limited to, butadiene and / or isoprene. Preferably, the conjugated diene is butadiene.

[0022] According to the ethylene copolymer of the present invention, the α-olefin is preferably a C3-C6 α-olefin. Specific examples of the α-olefin may include, but are not limited to, propylene, 1-butene, 1-pentene, and 1-hexene. Preferably, the α-olefin is propylene.

[0023] According to the ethylene copolymer of the present invention, the content of the conjugated diene structural unit is 5-20 mol%, based on the total amount of the ethylene copolymer, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 mol%. Preferably, the content of the conjugated diene structural unit is 8-17 mol%, based on the total amount of the ethylene copolymer.

[0024] According to the ethylene copolymer of the present invention, the molar ratio of the ethylene structural unit to the conjugated diene structural unit is 2-10:1, for example, it can be: 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1, 5:1, 5.1:1, 5.2:1, 5.3:1, 5.4:1, 5.5:1, 5. 6:1, 5.7:1, 5.8:1, 5.9:1, 6:1, 6.1:1, 6.2:1, 6.3:1, 6.4:1, 6.5:1, 6.6:1, 6.7:1, 6.8:1, 6.9:1, 7:1, 7.1:1, 7.2:1, 7.3:1, 7.4:1, 7.5:1, 7.6:1, 7.7:1, 7.8: 1, 7.9:1, 8:1, 8.1:1, 8.2:1, 8.3:1, 8.4:1, 8.5:1, 8.6:1, 8.7:1, 8.8:1, 8.9:1, 9:1, 9.1:1, 9.2:1, 9.3:1, 9.4:1, 9.5:1, 9.6:1, 9.7:1, 9.8:1, 9.9:1, or 10:1.

[0025] According to the ethylene copolymer of the present invention, the content of the α-olefin structural unit can be 5-55 mol%, preferably 6-50 mol%, more preferably 8-40 mol%, and even more preferably 10-30 mol%, based on the total amount of the ethylene copolymer.

[0026] The ethylene copolymer according to the present invention contains anti-1,4-structural units, which are structural units formed by 1,4-polymerization of the conjugated diene and having anti-1,4-double bonds. Based on the total amount of conjugated diene structural units in the ethylene copolymer according to the present invention, the content of the anti-1,4-structural units is 10-50 mol%, preferably 20-48 mol%, more preferably 25-45 mol%, and even more preferably 30-45 mol%.

[0027] According to the ethylene copolymer of the present invention, the content of cis-1,4-structural units having cis-1,4-double bonds formed by 1,4-polymerization of the conjugated diene is low. Generally, based on the total amount of conjugated diene structural units in the ethylene copolymer, the content of cis-1,4-structural units having cis-1,4-double bonds formed by 1,4-polymerization of the conjugated diene is 5 mol% or less. Preferably, based on the total amount of conjugated diene structural units in the ethylene copolymer, the content of cis-1,4-structural units having cis-1,4-double bonds formed by 1,4-polymerization of the conjugated diene is 0.

[0028] According to the ethylene copolymer of the present invention, the content of the structural units formed by the 1,3-polymerization of the conjugated diene is low. Generally, based on the total amount of the conjugated diene structural units in the ethylene copolymer, the content of the 1,3-structural units formed by the 1,3-polymerization of the conjugated diene is 5 mol% or less. Preferably, based on the total amount of the conjugated diene structural units in the ethylene copolymer, the content of the 1,3-structural units formed by the 1,3-polymerization of the conjugated diene is 0.

[0029] According to the ethylene copolymer of the present invention, the ethylene copolymer contains 1,2-structural units formed by 1,2-polymerization of conjugated dienes.

[0030] The 1,2-polymer structural units include 1,2-polymer vinyl structural units formed by 1,2-polymerization of conjugated dienes and having side chain double bonds, 1,2-cyclopropane ring structural units formed by 1,2-polymerization of conjugated dienes and having cyclopropane rings, and 1,5-cyclopentane ring structural units formed by 1,2-polymerization of conjugated dienes and having cyclopentane rings.

[0031] Taking butadiene as an example, the 1,2-polymer vinyl structural unit is shown in Formula 2, the 1,2-cyclopropane ring structural unit is shown in Formula 3, and the 1,5-cyclopentane ring structural unit is shown in Formula 4:

[0032]

[0033] The ethylene copolymers according to the present invention have a low content of 1,2-polymer vinyl structural units. Generally, based on the total amount of conjugated diene structural units in the ethylene copolymer, the content of said 1,2-polymer vinyl structural units is 5 mol% or less, preferably 0. The ethylene copolymers according to the present invention also have a low content of 1,2-cyclopropane ring structural units. Generally, based on the total amount of conjugated diene structural units in the ethylene copolymer, the content of said 1,2-cyclopropane ring structural units is 5 mol% or less, preferably 0.

[0034] According to the ethylene copolymer of the present invention, the molar ratio of the anti-1,4-structural unit to the 1,5-cyclopentane ring structural unit is 0.1-1:1, preferably 0.2-0.98:1, more preferably 0.3-0.96:1, and even more preferably 0.4-0.95:1. In the ethylene copolymer of the present invention, the structural unit formed by the 1,2-polymerization of the conjugated diene is predominantly the 1,5-cyclopentane ring structural unit. Introducing the 1,5-cyclopentane ring structural unit into the ethylene copolymer can effectively improve the heat resistance and mechanical properties of the ethylene copolymer.

[0035] In this invention, 1,2-polymer structural unit refers to a structural unit formed by 1,2-polymerization of conjugated dienes (i.e., 1,2-addition), 1,4-polymer structural unit refers to a structural unit formed by 1,4-polymerization of conjugated dienes (i.e., 1,4-addition), and 1,3-polymer structural unit refers to a structural unit formed by 1,3-polymerization of conjugated dienes (i.e., 1,3-addition).

[0036] In this invention, the microstructure composition of the ethylene copolymer was determined by nuclear magnetic resonance spectroscopy.

[0037] The glass transition temperature (T) of the ethylene copolymer according to the present invention g Low. Generally, the glass transition temperature of the ethylene copolymer according to the present invention is below -25°C, typically in the range of -25°C to -60°C.

[0038] According to one embodiment of the ethylene copolymer of the present invention, the glass transition temperature of the ethylene copolymer is -40°C to -55°C. The ethylene copolymer according to this embodiment has no melting point in a temperature range below 60°C. That is, the ethylene copolymer according to this embodiment has no melting point. According to this embodiment, the molar ratio of the trans-1,4-structural unit to the 1,5-cyclopentane ring structural unit is preferably 0.3-0.7:1, more preferably 0.4-0.65:1.

[0039] In another embodiment of the ethylene copolymer according to the present invention, the glass transition temperature of the ethylene copolymer is -30°C to -40°C. The ethylene copolymer according to this embodiment has a melting point. Preferably, the melting point of the ethylene copolymer according to this embodiment is in the temperature range of 20-60°C. According to this embodiment, the molar ratio of the trans-1,4-structural unit to the 1,5-cyclopentane ring structural unit is preferably 0.72-1:1, more preferably 0.75-0.95:1.

[0040] In this invention, the melting point and glass transition temperature of the ethylene copolymer were determined by differential scanning calorimetry (DSC).

[0041] According to the present invention, the number-average molecular weight of the ethylene copolymer can be from 10,000 to 200,000, preferably from 20,000 to 150,000. According to the present invention, the number-average molecular weight of the ethylene copolymer can be, for example, from 10,000 to 120,000, from 15,000 to 110,000, or from 20,000 to 100,000. According to the present invention, the molecular weight distribution index of the ethylene copolymer can be from 1.5 to 3.5.

[0042] In this invention, the molecular weight (g / mol) and molecular weight distribution index were determined by gel permeation chromatography (GPC), with monodisperse polystyrene as the standard.

[0043] According to a second aspect of the present invention, the present invention provides a method for preparing an ethylene copolymer, the method comprising contacting ethylene, α-olefin and conjugated diene with a metallocene catalyst and methylaluminoxane under olefin polymerization conditions, wherein the metallocene catalyst is selected from rac-ethylenebis(1-indenyl)zirconia and diphenylmethylene(cyclopentadienyl)(fluorenyl)zirconia.

[0044] According to the preparation method of the present invention, zirconium dichloride selected from rac-ethylene bis(1-indenyl) dichloride and diphenylmethylene(cyclopentadienyl)(fluorenyl) dichloride are used, and methylaluminoxane is used as a co-catalyst. This method can not only synthesize ethylene, α-olefins and conjugated dienes, but also prepare ethylene copolymers containing trans-1,4-structural units.

[0045] According to the preparation method of the present invention, the molar ratio of the methylaluminoxane to the metallocene catalyst is preferably 800-10000:1, more preferably 1000-9000:1, and even more preferably 1500-8500:1, wherein the methylaluminoxane is calculated as aluminum and the metallocene catalyst is calculated as zirconium.

[0046] According to the preparation method of the present invention, the amounts of ethylene, α-olefin, and conjugated diene can be selected according to the desired composition of the ethylene copolymer. Preferably, the amounts of ethylene, α-olefin, and conjugated diene are such that the content of conjugated diene structural units derived from the conjugated diene in the ethylene copolymer is 5-20 mol%, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 mol%. Preferably, the amounts of ethylene, α-olefin, and conjugated diene are such that the content of conjugated diene structural units derived from the conjugated diene in the ethylene copolymer is 8-17 mol. According to the preparation method of the present invention, the amount of ethylene and conjugated diene is such that the molar ratio of ethylene structural units derived from ethylene to conjugated diene structural units in the prepared ethylene copolymer is 2-10:1, for example, it can be 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1, 5:1, 5.1:1, 5.2:1, 5.3:1. 5.4:1, 5.5:1, 5.6:1, 5.7:1, 5.8:1, 5.9:1, 6:1, 6.1:1, 6.2:1, 6.3:1, 6.4:1, 6.5:1, 6.6:1, 6.7:1, 6.8:1, 6.9:1, 7:1, 7.1:1, 7.2:1, 7.3:1, 7.4:1, 7.5:1, 7.6:1, 7. 7:1, 7.8:1, 7.9:1, 8:1, 8.1:1, 8.2:1, 8.3:1, 8.4:1, 8.5:1, 8.6:1, 8.7:1, 8.8:1, 8.9:1, 9:1, 9.1:1, 9.2:1, 9.3:1, 9.4:1, 9.5:1, 9.6:1, 9.7:1, 9.8:1, 9.9:1, or 10:1. According to the preparation method of the present invention, the amounts of ethylene, α-olefin, and conjugated diene are such that the content of α-olefin structural units in the ethylene copolymer can be 5-55 mol%, preferably 6-50 mol%, more preferably 8-40 mol%, and even more preferably 10-30 mol%.

[0047] According to the preparation method of the present invention, the contacting of the ethylene, α-olefin, and conjugated diene can be carried out at a temperature of -50°C to 150°C, preferably at a temperature of 10-120°C, more preferably at a temperature of 30-90°C, and even more preferably at a temperature of 40-70°C. According to the preparation method of the present invention, during the contact polymerization of ethylene and the conjugated diene, the pressure of the ethylene can be 0-10 MPa, preferably 0-5 MPa, more preferably 0-3 MPa, and even more preferably 0-2 MPa, wherein the pressure is measured in gauge pressure (G).

[0048] According to the preparation method of the present invention, the contact can be carried out in the presence of a molecular weight regulator, or it can be carried out without the molecular weight regulator. When a molecular weight regulator is used, the amount of the molecular weight regulator is preferably such that the number average molecular weight of the prepared ethylene copolymer is 10,000 to 200,000, more preferably such that the number average molecular weight of the prepared ethylene polymer is 20,000 to 150,000, for example 10,000 to 120,000, 15,000 to 110,000, or 20,000 to 100,000. The molecular weight regulator can be conventionally selected, preferably hydrogen.

[0049] According to the preparation method of the present invention, solution polymerization can be used. In solution polymerization, solvents that can be used include C6-C... 12 Aromatics, C6-C 12 Halogenated aromatics, C5-C 10 Straight-chain alkanes and C5-C 10 Cycloalkanes, such as one or more of toluene, chlorobenzene, dichlorobenzene, n-hexane, and cyclohexane.

[0050] According to a third aspect of the present invention, the present invention provides an ethylene copolymer prepared by the method described in the second aspect of the present invention.

[0051] The ethylene copolymer prepared by the method described in the second aspect of the present invention contains 1,4-structural units formed by 1,4-polymerization of conjugated dienes, and the 1,4-structural units are predominantly in the form of inverse 1,4-structural units.

[0052] According to a fourth aspect of the present invention, the present invention provides a composition comprising an ethylene copolymer and a crosslinking agent, wherein the ethylene copolymer is the ethylene copolymer described in the first or third aspect of the present invention.

[0053] The crosslinking agent can be a substance sufficient to crosslink the vinyl groups in the ethylene copolymer. Specifically, the crosslinking agent can be one or more of sulfur, sulfur monochloride, selenium, tellurium, and peroxides. In a preferred embodiment, the crosslinking agent is a peroxide, such as dicumyl peroxide.

[0054] The compositions according to the invention may further contain a vulcanization accelerator to promote vulcanization, thereby shortening the vulcanization time, reducing the vulcanization temperature, and reducing the amount of vulcanizing agent used. The vulcanization accelerator may be a commonly used substance capable of achieving the above-mentioned functions, such as triallyl isocyanurate. The compositions according to the invention may also contain other components, such as one or more of antioxidants and fillers, depending on specific requirements. Preferred examples of the fillers may include, but are not limited to, carbon black.

[0055] According to a fifth aspect of the present invention, a crosslinked polymer is provided, which is formed by crosslinking an ethylene copolymer described in the first or third aspect of the present invention. The ethylene copolymer described in the first or third aspect of the present invention can be contacted with a crosslinking agent to undergo a crosslinking reaction, thereby obtaining the crosslinked polymer described in the fifth aspect of the present invention.

[0056] According to a sixth aspect of the present invention, a tire is provided in which at least one constituent element comprises the ethylene copolymer described in the first aspect of the present invention, the composition described in the fourth aspect of the present invention, or the crosslinked polymer described in the fifth aspect of the present invention.

[0057] The present invention will be described in detail below with reference to embodiments, but this does not limit the scope of the invention.

[0058] In the following examples and comparative examples, the molecular weight and molecular weight distribution index (M) of the polymers are... w / M n The assay was performed using an Agilent Technologies 1260 Infinity II high-temperature gel permeation chromatograph, employing two MIXD-B columns (300 × 7.5 mm) and one Guard column (50 × 7.5 mm). The mobile phase was trichlorobenzene, with a flow rate of 1 mL / min; the sample concentration was 1 mg / mL, and the injection volume was 200 μL; the test temperature was 150 °C; and monodistributed polystyrene was used as the standard sample.

[0059] In the following examples and comparative examples, nuclear magnetic resonance spectroscopy was performed using a commercially available 400MHz nuclear magnetic resonance spectrometer from Bruker. When testing the microstructure of the polymer, deuterated o-dichlorobenzene was used as the solvent and tetramethylsilicon (TMS) was used as the internal standard. In this context, the ethylene / propylene / butadiene molar ratio refers to the molar ratio of ethylene structural units derived from ethylene, propylene structural units derived from propylene, and butadiene structural units derived from butadiene in the prepared ethylene copolymer. "1,2-structure" refers to a structural unit formed by the polymerization of conjugated dienes via 1,2-addition; "1,4-structure" refers to a structural unit formed by the polymerization of conjugated dienes via 1,4-addition; "trans-1,4-structure" refers to a structural unit formed by the polymerization of conjugated dienes via 1,4-addition and possessing an anti-1,4-double bond; "cis-1,4-structure" refers to a structural unit formed by the polymerization of conjugated dienes via 1,4-addition and possessing a cis-1,4-double bond; and "1,3-structure" refers to a structural unit formed by the polymerization of conjugated dienes via 1,3-addition. "Vinyl" refers to a structural unit formed by the 1,2-polymerization of conjugated dienes and possessing a side-chain double bond (taking butadiene as an example, vinyl is...). "Cyclopropane ring" refers to a structural unit of a conjugated diene formed by 1,2-polymerization that has a cyclopropane ring (taking butadiene as an example, the cyclopropane ring is...). "Cyclopentane ring" refers to the structural unit of a conjugated diene formed by 1,2-polymerization and possessing a 1,5-cyclopentane ring (taking butadiene as an example, the cyclopentane ring is...). ).

[0060] In the following examples and comparative examples, the glass transition temperature (T) is... g ) and melting point (T m Differential scanning calorimetry was used for determination, specifically a commercially available METTLER DSC1 differential thermal analyzer with a heating rate of 20℃ / min and a scanning temperature range of -100℃ to 150℃.

[0061] Examples 1-6 are used to prepare ethylene copolymers according to the present invention and their preparation methods.

[0062] Example 1

[0063] A 500 mL stainless steel reactor was fully purged with nitrogen, then with hydrogen. 120 g toluene, 12 mmol methylaluminoxane (10% by weight toluene solution), 924 mmol butadiene, and 0.5 kg / cm³ of [unclear - likely a specific gas or solution] were added. 2 G hydrogen gas. At 60℃, using 8.1 kg / cm³ 2A pre-mixed gas mixture of ethylene and propylene (ethylene / propylene molar ratio of 1) is introduced to saturate both the liquid and gas phases. Then, 5 μmol of rac-ethylenebis(1-indenyl)zirconia dichloride, previously dissolved in toluene, is added to initiate polymerization. The ethylene and propylene gas mixture is continuously supplied to maintain a total pressure of 8.1 kg / cm². 2 G. After polymerization for 15 minutes, a small amount of methanol was added to terminate the reaction. The product was poured into a large amount of ethanol containing hydrochloric acid (HCl concentration of 2‰ by weight) for precipitation. The solid was separated by filtration and washed with ethanol. The washed solid was dried in a vacuum oven until its weight no longer decreased, yielding the ethylene copolymer according to the present invention. The test results of the property parameters of the prepared ethylene copolymer are listed in Table 1.

[0064] Example 2

[0065] Ethylene copolymers were prepared using the same method as in Example 1, except that no hydrogen was added. The property parameters of the resulting ethylene copolymers are listed in Table 1.

[0066] Example 3

[0067] Ethylene copolymers were prepared using the same method as in Example 2, except that the ethylene / propylene molar ratio in the mixed gas was 0.5. The property parameters of the prepared ethylene copolymers are listed in Table 1.

[0068] Example 4

[0069] A 500 mL stainless steel reactor was fully purged with nitrogen, then with hydrogen. 120 g of toluene, 42 mmol of methylaluminoxane (10% by weight toluene solution), and 462 mmol of butadiene were added. The reactor was then heated at 60 °C using 8.1 kg / cm³ of nitrogen. 2 A pre-mixed gas mixture of ethylene and propylene (ethylene / propylene molar ratio of 5) is introduced to saturate both the liquid and gas phases. Then, 5 μmol of diphenylmethylene (cyclopentadiene)(9-fluorenyl)zirconium dichloride, previously dissolved in toluene, is added to initiate polymerization. The ethylene and propylene gas mixture is continuously supplied to maintain a total pressure of 8.1 kg / cm². 2 G. After polymerization for 15 minutes, a small amount of methanol was added to terminate the reaction. The product was poured into a large amount of ethanol containing hydrochloric acid (HCl concentration of 2‰ by weight) for precipitation. The solid was separated by filtration and washed with ethanol. The washed solid was dried in a vacuum oven until its weight no longer decreased, yielding the ethylene copolymer according to the present invention. The test results of the property parameters of the prepared ethylene copolymer are listed in Table 1.

[0070] Example 5

[0071] Ethylene copolymers were prepared using the same method as in Example 4, except that the amount of butadiene used was 1387 mmol and the molar ratio of ethylene to propylene in the mixed gas was 0.5. The test results of the property parameters of the prepared ethylene copolymers are listed in Table 1.

[0072] Comparative Example 1

[0073] Ethylene copolymers were prepared using the same method as in Example 1, except that rac-ethylene bis(1-indenyl)zirconia was replaced with an equimolar amount of rac-dimethylsilyl bis(1-indenyl)zirconia.

[0074] Comparative Example 2

[0075] The ethylene copolymer was prepared using the same method as in Example 4, except that diphenylmethylene(cyclopentadiene)(9-fluorenyl)zirconia was replaced with an equimolar amount of dimethylsilyl(cyclopentadiene)(9-fluorenyl)zirconia.

[0076] Comparative Example 3

[0077] The ethylene copolymer was prepared using the same method as in Example 1, except that methylaluminoxane was replaced with triisobutylaluminum.

[0078] Example 6

[0079] Ethylene copolymers were prepared using the same method as in Example 4, except that the amount of butadiene used was 742 mmol. The test results of the property parameters of the prepared ethylene copolymers are listed in Table 1.

[0080] As can be seen from the results in Table 1, the ethylene copolymers according to the present invention contain ethylene structural units derived from ethylene, propylene structural units derived from propylene, and butadiene structural units derived from butadiene. The ethylene copolymers according to the present invention contain 1,4-structural units formed by 1,4-polymerization of butadiene, and are predominantly of the inverse 1,4-structure.

[0081] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

[0082]

Claims

1. An ethylene copolymer comprising ethylene structural units derived from ethylene, α-olefin structural units derived from α-olefins, and conjugated diene structural units derived from conjugated dienes, wherein the molar ratio of the ethylene structural units to the conjugated diene structural units is 2-10:1, and the content of the conjugated diene structural units is 5-20 mol% based on the total amount of the ethylene copolymer. The ethylene polymer contains trans-1,4-structural units and 1,5-cyclopentane ring structural units, wherein the trans-1,4-structural units are structural units formed by 1,4-polymerization of the conjugated diene and having trans-1,4-double bonds, and the 1,5-cyclopentane ring structural units are structural units formed by 1,4-polymerization of the conjugated diene and having trans-1,4-double bonds. Based on the total amount of conjugated diene structural units in the ethylene copolymer, the content of the trans-1,4-structural units is 10-50 mol%, the molar ratio of the trans-1,4-structural units to the 1,5-cyclopentane ring structural units is 0.1-1:1, based on the total amount of conjugated diene structural units in the ethylene copolymer, the content of the cis-1,4-structural units formed by 1,4-polymerization and having cis-1,4-double bonds is less than 5 mol%, and the content of the 1,3-structural units formed by 1,3-polymerization is less than 5 mol%.

2. The ethylene copolymer according to claim 1, wherein, The ethylene copolymer contains 1,5-cyclopentane ring structural units, which are structural units formed by the 1,2-polymerization of conjugated dienes, and the molar ratio of the trans-1,4-structural units to the 1,5-cyclopentane ring structural units is 0.4-0.95:

1.

3. The ethylene copolymer according to claim 1 or 2, wherein, Based on the total amount of conjugated diene structural units in the ethylene copolymer, the content of cis-1,4-structural units formed by 1,4-polymerization and having cis-1,4-double bonds in the conjugated diene is 0.

4. The ethylene copolymer according to claim 1 or 2, wherein, Based on the total amount of conjugated diene structural units in the ethylene copolymer, the content of 1,3-structural units formed by 1,3-polymerization of the conjugated diene is 0.

5. The ethylene copolymer according to claim 1 or 2, wherein, The glass transition temperature of this ethylene copolymer is below -25°C.

6. The ethylene copolymer according to claim 1 or 2, wherein, The glass transition temperature of this ethylene copolymer is -25°C to -60°C.

7. The ethylene copolymer according to claim 1 or 2, wherein, The glass transition temperature of this ethylene copolymer is -40°C to -55°C.

8. The ethylene copolymer according to claim 7, wherein, This ethylene copolymer has no melting point in the temperature range below 60°C.

9. The ethylene copolymer according to claim 1 or 2, wherein, The glass transition temperature of this ethylene copolymer is -30°C to -40°C.

10. The ethylene copolymer according to claim 9, wherein, The ethylene copolymer has no melting point or has a melting point in the temperature range of 20-60°C.

11. The ethylene copolymer according to claim 1 or 2, wherein, The conjugated diene is butadiene.

12. The ethylene copolymer according to claim 1 or 2, wherein, The α-olefin is a C3-C6 α-olefin.

13. The ethylene copolymer according to claim 1 or 2, wherein, The α-olefin is propylene.

14. The ethylene copolymer according to claim 1 or 2, wherein, The number average molecular weight of this ethylene copolymer is between 10,000 and 200,000.

15. The ethylene copolymer according to claim 1 or 2, wherein, The number-average molecular weight of this ethylene copolymer is between 20,000 and 150,000.

16. The ethylene copolymer according to claim 1 or 2, wherein, The molecular weight distribution index of this ethylene copolymer is 1.5-3.

5.

17. The ethylene copolymer according to claim 1 or 2, wherein, Based on the total amount of conjugated diene structural units in the ethylene copolymer, the content of the anti-1,4-structural units is 30-45 moles.

18. A method for preparing an ethylene copolymer, the method comprising contacting ethylene, α-olefin and conjugated diene with a metallocene catalyst and methylaluminoxane under olefin polymerization conditions, wherein the metallocene catalyst is selected from rac-ethylenebis(1-indenyl)zirconium chloride and diphenylmethylene(cyclopentadienyl)(fluorenyl)zirconium chloride.

19. The method according to claim 18, wherein, The molar ratio of the methylaluminoxane to the metallocene catalyst is 800-10000:1, wherein the methylaluminoxane is based on aluminum and the metallocene catalyst is based on zirconium.

20. The method according to claim 18 or 19, wherein, The contact temperature is between -50°C and 150°C.

21. The method according to claim 18 or 19, wherein, The amounts of ethylene, α-olefin, and conjugated diene used are such that the content of conjugated diene structural units derived from conjugated diene in the ethylene copolymer is 5-20 mol%, and the molar ratio of ethylene structural units derived from ethylene to the conjugated diene structural units is 2-10:

1.

22. The method according to claim 18 or 19, wherein, The conjugated diene is butadiene.

23. The method according to claim 18 or 19, wherein, The α-olefin is a C3-C6 α-olefin.

24. The method according to claim 18 or 19, wherein, The α-olefin is propylene.

25. An ethylene copolymer prepared by the method of any one of claims 18-24.

26. A composition comprising an ethylene copolymer and a crosslinking agent, wherein, The ethylene copolymer is the ethylene copolymer according to any one of claims 1-17 and 25.

27. A crosslinked polymer formed by crosslinking an ethylene copolymer according to any one of claims 1-17 and 25.

28. A tire, wherein at least one constituent element comprises an ethylene copolymer as described in any one of claims 1-17 and 25, a composition as described in claim 26, or a crosslinked polymer as described in claim 27.

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