Electrolyte-resistant modified ethylene propylene diene monomer and preparation method thereof

Abstract

The invention discloses an electrolyte-resistant modified ethylene propylene diene monomer and a preparation method thereof, and belongs to the technical field of rubber. The preparation method comprises the following steps: mixing ethylene propylene diene monomer, an active agent and part of a reinforcing agent, adding functionalized nitrile rubber and a compatilizer for continuous mixing, adding the rest of the reinforcing agent and a barrier agent for continuous mixing to obtain rubber master batch, mixing the rubber master batch, part of a vulcanizing agent and an auxiliary vulcanizing agent for primary vulcanization mixing, and carrying out secondary vulcanization mixing to obtain rubber master batch; and adding the rest vulcanizing agent into the mixed system to perform secondary vulcanization mixing, finally performing homogenization and sheet discharging on the vulcanized rubber material, and performing post vulcanization and heat treatment to obtain the rubber material. The electrolyte-resistant modified ethylene propylene diene monomer provided by the invention has excellent electrolyte resistance, swelling resistance and high elasticity, permeation and diffusion of electrolyte and harmful substances can be delayed, and the problems that two-phase interfaces are weak in bonding and easy to separate for a long time are solved.

Description

Technical Field

[0001] This invention belongs to the field of rubber technology, specifically relating to an electrolyte-resistant modified EPDM rubber and its preparation method. Background Technology

[0002] Ethylene propylene diene monomer (EPDM) rubber is a synthetic rubber copolymerized from ethylene, propylene, and a non-conjugated diene third monomer. Its saturated main chain chemical structure endows it with excellent weather resistance, ozone aging resistance, superior electrical insulation properties, and low compression set. Simultaneously, EPDM molecular chains are flexible, possessing good elasticity and cushioning properties, and its processing technology is mature. These combined characteristics make it an ideal material for sealing, damping, and insulation applications. However, the non-polar nature of its molecular structure limits its application in certain chemical media.

[0003] When traditional EPDM is used in lithium-ion battery environments, its core challenge lies in its inability to withstand highly polar carbonate electrolytes. Due to the significant difference in polarity between EPDM and the electrolyte, their compatibility is extremely poor. Small electrolyte molecules strongly penetrate and swell the non-polar network of EPDM, leading to seal volume expansion, a sharp decrease in mechanical strength, loss of sealing pressure, and ultimately, leakage risks. To improve electrolyte resistance, the industry typically uses blending with fluororubber or adding fluorinated additives for modification. While these solutions alleviate the swelling problem to some extent, they introduce environmental hazards and high costs. More importantly, simple physical blending often results in phase separation under long-term electrolyte immersion or dynamic stress due to weak interfacial bonding between EPDM and oil-resistant polar rubbers (such as fluororubber and hydrogenated nitrile rubber), leading to performance degradation.

[0004] Based on the above, it is essential to propose a new electrolyte-resistant modified EPDM rubber and its preparation method. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an electrolyte-resistant modified EPDM rubber and its preparation method.

[0006] The first aspect of this invention is to provide an electrolyte-resistant modified EPDM rubber, comprising the following raw materials by mass parts: 100 parts of EPDM rubber, 28-32 parts of functionalized nitrile butadiene rubber, 8-12 parts of compatibilizer, 18-22 parts of reinforcing agent, 5-7 parts of barrier agent, 4-7 parts of activator, 0.5-2.5 parts of vulcanizing agent, and 1-3 parts of co-vulcanizing agent; The functionalized nitrile butadiene rubber is prepared by the following steps: (1) Mix 4-vinylepoxycyclohexane and acrylic acid, add diluent to dilute, and then add initiator to obtain graft solution; (2) The hydrogenated nitrile rubber is softened by heat to form a roll-wrapping rubber; (3) The grafting liquid is added to the rubber of the roller and mixed. Then an antioxidant is added and mixed. After cooling and curing, functionalized nitrile rubber is obtained.

[0007] It should be noted that this invention creatively uses hydrogenated nitrile butadiene rubber (HNBR) as a matrix, and introduces highly reactive epoxy groups and strongly polar carboxyl groups onto its molecular chain through a melt grafting chemical reaction. Using a peroxide initiator, free radicals are generated under mechanical shear and thermal action, which abstract α-hydrogens from the unsaturated double bonds on the HNBR main chain or attack the double bonds themselves, forming rubber macromolecular free radicals. These free radicals then initiate the graft copolymerization of 4-vinylepoxycyclohexane and acrylic acid monomers, thereby firmly attaching the epoxy and carboxyl groups to the HNBR molecular chain via covalent bonds.

[0008] In some embodiments, the diluent is selected from at least one of anhydrous ethanol and acetone; the initiator is selected from at least one of dicumyl peroxide and benzoyl peroxide; and the antioxidant is selected from at least one of antioxidant 1010, antioxidant 168, and antioxidant 1076.

[0009] In some embodiments, the mass ratio of 4-vinylepoxycyclohexane, acrylic acid, diluent, and initiator is 1-3:0.5-1.5:4-6:0.2-0.5.

[0010] In some embodiments, the mass of hydrogenated nitrile butadiene rubber is 48-52 times the mass of 4-vinylcyclohexane; the mass of antioxidant is 0.3-0.7% of the mass of hydrogenated nitrile butadiene rubber.

[0011] In some embodiments, the hydrogenated nitrile rubber has an acrylonitrile content of 32-36% and a degree of hydrogenation ≥95%.

[0012] In some implementations, in step (2), the heating temperature is 58-62°C; in step (3), the curing is to place the food in a dark environment at a temperature of <25°C for more than 24 hours.

[0013] A second aspect of this invention is to provide a method for preparing electrolyte-resistant modified EPDM rubber, comprising the following steps: S1: Mix EPDM rubber, activator and part of the reinforcing agent, add functionalized nitrile rubber and compatibilizer and continue mixing, then add the remaining reinforcing agent and barrier agent and continue mixing to obtain masterbatch. S2: Mix the masterbatch, part of the vulcanizing agent and the vulcanizing aid for the first vulcanization compounding; S3: Add the remaining vulcanizing agent to the S2 mixture system for a second vulcanization and mixing; S4: The rubber compound after S3 vulcanization is homogenized and sheeted out. After post-vulcanization and heat treatment, the modified EPDM rubber resistant to electrolyte is obtained.

[0014] It should be noted that this invention employs stepwise vulcanization to actively control the inherent differences in vulcanization activity between the functionalized nitrile rubber and EPDM phases. In a dynamic shear field, the vulcanizing agent added in the first stage preferentially reacts with the more active functionalized nitrile rubber (rich in functional groups and unsaturation), rapidly crosslinking to form highly crosslinked microregions. The vulcanizing agent added in the second stage then initiates crosslinking of the less active EPDM matrix, resulting in continuous crosslinking. The entire process continues under strong shear, ensuring that the crosslinked functionalized nitrile rubber particles are continuously dispersed, refined, and stabilized within the EPDM matrix.

[0015] In some embodiments, the compatibilizer is maleic anhydride-grafted EPDM; the reinforcing agent is selected from at least one of silica and carbon black; the barrier agent is selected from at least one of organically modified montmorillonite, organically modified kaolin, and organically modified hydrotalcite; the activator is a mixture of zinc oxide and stearic acid in a mass ratio of 4.5-5.5:0.5-1.5; the vulcanizing agent is selected from at least one of dicumyl peroxide, 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane, and benzoyl peroxide; and the co-vulcanizing agent is selected from at least one of triallyl isocyanurate and triallyl cyanurate.

[0016] In some embodiments, in S1, the overall mixing temperature is 100-110℃; in S2, the temperature of the first vulcanization mixing is 155-165℃, the rotation speed is 60 rpm, and the mixing time is 2-3 min; in S3, the temperature of the second vulcanization mixing is 150-160℃, and the mixing time is 4-5 min.

[0017] In some embodiments, in S4, post-vulcanization involves molding the film at 160-170°C and 8-12 MPa for 10-20 minutes, and heat treatment involves heat-treating the molded product at 140-160°C for 3-5 hours.

[0018] Compared with the prior art, the present invention has the following technical effects: 1. This invention creatively functionalizes hydrogenated nitrile butadiene rubber by introducing highly reactive epoxy groups and strongly polar carboxyl groups onto its molecular chain. During vulcanization, the epoxy groups can undergo ring-opening grafting with the EPDM matrix to form strong covalent bonds, while the carboxyl groups form strong polar forces with the compatibilizer, firmly connecting the polar oil-resistant phase (HNBR) and the non-polar matrix phase (EPDM). This solves the problem of weak interfacial bonding and easy long-term separation between the two phases, thus preparing a functionalized rubber with both excellent electrolyte resistance and strong interfacial bonding ability.

[0019] 2. This invention improves the traditional dynamic vulcanization process by controlling the phased addition of the vulcanizing agent and actively utilizing the difference in vulcanization activity between the two phases of rubber. During the processing, a stable structure with strong interfacial bonding is constructed, resulting in a low volume swelling rate and a better anti-swelling level of the material under long-term immersion in the electrolyte. This achieves both anti-swelling properties and high elasticity that are difficult to achieve with a single material.

[0020] 3. This invention also incorporates a barrier agent. By introducing organically modified layered nano-clay (such as montmorillonite), it is arranged at the interface between the functionalized nitrile rubber dispersion phase and the EPDM matrix to form a barrier network. This significantly delays the penetration and diffusion of electrolyte and harmful substances. In synergy with chemical protection, it achieves multi-level and high-efficiency protection, effectively improving the electrolyte resistance of the rubber matrix.

[0021] 4. The electrolyte-resistant modified EPDM rubber provided by this invention does not contain fluorinated polymers or additives commonly used in the industry that have environmental and cost issues. It is environmentally friendly and solves the problem that traditional materials cannot balance high performance, environmental protection and cost. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments.

[0023] Example 1 An electrolyte-resistant modified EPDM rubber comprises the following raw materials by mass parts: 100 parts EPDM rubber, 30 parts functionalized nitrile butadiene rubber, 10 parts compatibilizer, 20 parts reinforcing agent, 6 parts barrier agent, 5 parts activator, 1.5 parts vulcanizing agent, and 2 parts co-vulcanizing agent. The functionalized nitrile butadiene rubber is prepared by the following steps: (1) Mix 4-vinylcyclohexane oxide and acrylic acid, add anhydrous ethanol to mix and dilute, and then add dicumyl peroxide to mix and obtain graft solution; wherein, the mass ratio of 4-vinylcyclohexane oxide, acrylic acid, anhydrous ethanol and dicumyl peroxide is 2:1:5:0.35. (2) The hydrogenated nitrile rubber is softened by heating at 60°C to form a roller-wrapping rubber; wherein the acrylonitrile content of the hydrogenated nitrile rubber is 34% and the degree of hydrogenation is ≥95%; (3) The grafting liquid is added dropwise to the roller coating rubber and mixed. Then antioxidant 1010 is added and mixed again. After cooling, it is placed in the dark and at <25℃ for more than 24 hours to obtain functionalized nitrile rubber. The mass of hydrogenated nitrile rubber is 50 times the mass of 4-vinylepoxycyclohexane. The mass of antioxidant 1010 is 0.5% of the mass of hydrogenated nitrile rubber.

[0024] The above-mentioned electrolyte-resistant modified EPDM rubber is prepared by the following steps: S1: Ethylene propylene diene monomer (EPDM) rubber, activator, and 50% of the total mass of silica are mixed at 105°C. Functionalized nitrile butadiene rubber and maleic anhydride-grafted EPDM are added and mixed further. Then, the remaining silica and organically modified montmorillonite are added and mixed further to obtain the masterbatch. The activator is composed of zinc oxide and stearic acid in a mass ratio of 5:1. S2: Mix the masterbatch, dicumyl peroxide (60% of the total mass of dicumyl peroxide), and triallyl isocyanurate, and perform the first vulcanization mixing at 160°C and 60 rpm for 3 minutes. S3: Add the remaining dicumyl peroxide to the S2 mixture and perform a second vulcanization mixing at 155°C for 5 minutes; S4: The rubber compound after S3 vulcanization is homogenized and sheeted. The sheet is then molded at 165℃ and 10MPa for 15 minutes. The molded product is then heat-treated at 150℃ for 4 hours to obtain electrolyte-resistant modified EPDM rubber.

[0025] Example 2 An electrolyte-resistant modified EPDM rubber comprises the following raw materials by mass parts: 100 parts EPDM rubber, 32 parts functionalized nitrile butadiene rubber, 12 parts compatibilizer, 22 parts reinforcing agent, 7 parts barrier agent, 7 parts activator, 2.5 parts vulcanizing agent, and 3 parts co-vulcanizing agent. The functionalized nitrile butadiene rubber is prepared by the following steps: (1) Mix 4-vinylcyclohexane and acrylic acid, add acetone to dilute, and then add benzoyl peroxide to obtain a grafting solution; wherein the mass ratio of 4-vinylcyclohexane, acrylic acid, acetone and benzoyl peroxide is 3:1.5:6:0.5. (2) The hydrogenated nitrile rubber is heated and softened at 62°C to form a roller-wrapping rubber; wherein the acrylonitrile content of the hydrogenated nitrile rubber is 36% and the degree of hydrogenation is ≥95%; (3) The grafting liquid is added dropwise to the roller coating rubber and mixed. Then antioxidant 168 is added and mixed again. After cooling, it is placed in the dark and at <25℃ for more than 24 hours to obtain functionalized nitrile rubber. The mass of hydrogenated nitrile rubber is 52 times the mass of 4-vinylepoxycyclohexane. The mass of antioxidant 168 is 0.7% of the mass of hydrogenated nitrile rubber.

[0026] The above-mentioned electrolyte-resistant modified EPDM rubber is prepared by the following steps: S1: Ethylene propylene diene monomer (EPDM) rubber, activator, and 50% carbon black by mass are mixed at 110°C. Functionalized nitrile butadiene rubber and maleic anhydride-grafted EPDM are added and the mixture is further mixed. Then, the remaining carbon black and organically modified kaolin are added and the mixture is further mixed to obtain the masterbatch. The activator is composed of zinc oxide and stearic acid in a mass ratio of 5.5:1.5. S2: Mix the masterbatch, 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane (60% of the total mass of 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane), and triallyl cyanurate, and perform the first vulcanization mixing at 165°C and 60 rpm for 3 min. S3: Add the remaining 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane to the S2 mixture system, and carry out a second vulcanization mixing at 160°C for 5 minutes; S4: The rubber compound after S3 vulcanization is homogenized and sheeted. The sheet is then molded at 170℃ and 12MPa for 20 minutes. The molded product is then heat-treated at 160℃ for 5 hours to obtain electrolyte-resistant modified EPDM rubber.

[0027] Example 3 An electrolyte-resistant modified EPDM rubber comprises the following raw materials by mass parts: 100 parts EPDM rubber, 28 parts functionalized nitrile rubber, 8 parts compatibilizer, 18 parts reinforcing agent, 5 parts barrier agent, 4 parts activator, 0.5 parts vulcanizing agent, and 1 part co-vulcanizing agent. The functionalized nitrile butadiene rubber is prepared by the following steps: (1) Mix 4-vinylcyclohexane oxide and acrylic acid, add anhydrous ethanol to mix and dilute, and then add dicumyl peroxide to mix and obtain graft solution; wherein, the mass ratio of 4-vinylcyclohexane oxide, acrylic acid, anhydrous ethanol and dicumyl peroxide is 1:0.5:4:0.2. (2) The hydrogenated nitrile rubber is heated and softened at 58°C to form a roller-wrapping rubber; wherein the acrylonitrile content of the hydrogenated nitrile rubber is 32% and the degree of hydrogenation is ≥95%; (3) The grafting liquid is added dropwise to the roller coating rubber and mixed. Then antioxidant 1076 is added and mixed again. After cooling, it is placed in the dark and at <25℃ for more than 24 hours to obtain functionalized nitrile rubber. The mass of hydrogenated nitrile rubber is 48 times the mass of 4-vinylepoxycyclohexane. The mass of antioxidant 1076 is 0.3% of the mass of hydrogenated nitrile rubber.

[0028] The above-mentioned electrolyte-resistant modified EPDM rubber is prepared by the following steps: S1: Ethylene propylene diene monomer (EPDM) rubber, activator, and 50% of the total mass of silica are mixed at 100°C. Functionalized nitrile butadiene rubber and maleic anhydride-grafted EPDM are added and mixed further. Then, the remaining silica and organically modified hydrotalcite are added and mixed further to obtain the masterbatch. The activator is composed of zinc oxide and stearic acid in a mass ratio of 4.5:0.5. S2: Mix the masterbatch, benzoyl peroxide (60% of the total mass of benzoyl peroxide), and triallyl isocyanurate, and perform the first vulcanization mixing at 155°C and 60 rpm for 2 min. S3: Add the remaining benzoyl peroxide to the S2 mixture and perform a second vulcanization mixing at 150°C for 4 minutes; S4: The rubber compound after S3 vulcanization is homogenized and sheeted. The sheet is then molded at 160℃ and 8MPa for 10 minutes. The molded product is then heat-treated at 140℃ for 3 hours to obtain electrolyte-resistant modified EPDM rubber.

[0029] Example 4 The results are basically the same as in Example 1, except that, by mass, there are 29 parts of functionalized nitrile rubber, 9 parts of compatibilizer, 19 parts of reinforcing agent, 7 parts of barrier agent, 6 parts of activator, 1 part of vulcanizing agent, and 3 parts of co-vulcanizing agent.

[0030] Example 5 It is basically the same as Example 1, except that: by mass parts, there are 31 parts of functionalized nitrile rubber, 11 parts of compatibilizer, 21 parts of reinforcing agent, 5 parts of barrier agent, 7 parts of activator, 2 parts of vulcanizing agent, and 3 parts of co-vulcanizing agent.

[0031] Comparative Example 1 The method is basically the same as in Example 1, except that the functionalized nitrile rubber is replaced with the same amount of ordinary hydrogenated nitrile rubber without any functionalization modification, and the preparation step of the functionalized nitrile rubber is omitted.

[0032] Comparative Example 2 The process is basically the same as in Example 1, except that the stepwise vulcanization process is changed to a one-step vulcanization process. That is, steps S2 and S3 are changed to mixing the masterbatch, dicumyl peroxide and triallyl isocyanurate, and vulcanizing and mixing at 160°C and 60 rpm for 8 minutes.

[0033] Comparative Example 3 It is basically the same as Example 1, except that no barrier agent is added.

[0034] The performance of the EPDM rubbers prepared in Examples 1-5 and Comparative Examples 1-3 was tested, and the test results are shown in Table 1.

[0035] Volume swelling rate test: According to GB / T 1690-2020, the standard sample (e.g., 25mm×25mm×2mm) is immersed in 1 mol / L LiPF6 / EC+DMC+EMC (1:1:1 vol%) electrolyte at 60℃, and taken out after 60 days to calculate the volume swelling rate. Mechanical property retention rate test: Referring to GB / T 528-2009, similar to the volume swelling rate test, the sample is immersed in electrolyte. The tensile strength and elongation at break are tested before immersion and after 60 days, and the performance retention rate is calculated. Compression set test: Refer to GB / T 7759.1-2015, test at 125℃ for 22 hours, with a compression rate of 25%.

[0036] Table 1 As can be seen from Table 1, the test data of Examples 1-5 provided by the present invention are better than those of the comparative examples by bifunctional modification, step vulcanization and addition of barrier agents to nitrile rubber, and have better anti-swelling, mechanical properties and high elasticity.

[0037] As can be seen from the comparative examples, Comparative Example 1, without functionalization modification of the nitrile rubber, resulted in a significant increase in swelling rate and a low retention rate of mechanical properties. Under electrolyte immersion, polar electrolyte molecules easily penetrated the fragile phase interface, causing phase separation between the HNBR dispersed phase and the EPDM matrix, which macroscopically manifested as swelling and mechanical collapse. Comparative Example 2, using a one-step vulcanization process, showed an increase in both swelling and compression set. This was because the one-step vulcanization process led to competitive crosslinking between the EPDM and functionalized nitrile rubber phases. The functionalized nitrile rubber dispersed phase had uneven size and poor interpenetration with the crosslinking network of the matrix, resulting in uneven stress distribution and decreased long-term durability. Comparative Example 3, without the addition of a barrier agent, could not form a physical barrier at the material interface, allowing small electrolyte molecules to continuously and rapidly penetrate and diffuse, accelerating the decline in performance over time.

[0038] The above descriptions are merely some embodiments of the present invention. Those skilled in the art can make various modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A modified EPDM rubber resistant to electrolyte, characterized in that, By weight, it includes the following raw materials: 100 parts EPDM rubber, 28-32 parts functionalized nitrile butadiene rubber, 8-12 parts compatibilizer, 18-22 parts reinforcing agent, 5-7 parts barrier agent, 4-7 parts activator, 0.5-2.5 parts vulcanizing agent, and 1-3 parts co-vulcanizing agent. The functionalized nitrile butadiene rubber is prepared by the following steps: (1) Mix 4-vinylepoxycyclohexane and acrylic acid, add diluent to dilute, and then add initiator to obtain graft solution; (2) The hydrogenated nitrile rubber is softened by heat to form a roll-wrapping rubber; (3) The grafting liquid is added dropwise to the roller rubber and mixed, then an antioxidant is added and mixed again. After cooling and curing, the functionalized nitrile rubber is obtained.

2. The electrolyte-resistant modified EPDM rubber according to claim 1, characterized in that, The diluent is selected from at least one of anhydrous ethanol and acetone; the initiator is selected from at least one of dicumyl peroxide and benzoyl peroxide; and the antioxidant is selected from at least one of antioxidant 1010, antioxidant 168, and antioxidant 1076.

3. The electrolyte-resistant modified EPDM rubber according to claim 2, characterized in that, The mass ratio of the 4-vinylepoxycyclohexane, the acrylic acid, the diluent, and the initiator is 1-3:0.5-1.5:4-6:0.2-0.

5.

4. The electrolyte-resistant modified EPDM rubber according to claim 1, characterized in that, The mass of the hydrogenated nitrile butadiene rubber is 48-52 times the mass of the 4-vinylepoxycyclohexane; the mass of the antioxidant is 0.3-0.7% of the mass of the hydrogenated nitrile butadiene rubber.

5. The electrolyte-resistant modified EPDM rubber according to claim 4, characterized in that, The hydrogenated nitrile butadiene rubber has an acrylonitrile content of 32-36% and a degree of hydrogenation ≥95%.

6. The electrolyte-resistant modified EPDM rubber according to claim 1, characterized in that, In step (2), the heating temperature is 58-62℃; in step (3), the curing is to place the food in the dark and at a temperature of <25℃ for more than 24 hours.

7. A method for preparing the electrolyte-resistant modified EPDM rubber according to any one of claims 1-6, characterized in that, Includes the following steps: S1: Mix EPDM rubber, activator and part of the reinforcing agent, add functionalized nitrile rubber and compatibilizer and continue mixing, then add the remaining reinforcing agent and barrier agent and continue mixing to obtain masterbatch. S2: Mix the masterbatch, a portion of the vulcanizing agent and the vulcanizing aid for the first vulcanization compounding; S3: Add the remaining vulcanizing agent to the S2 mixture system for a second vulcanization and mixing; S4: The rubber compound after S3 vulcanization is homogenized and sheeted out. After post-vulcanization and heat treatment, the modified EPDM rubber resistant to electrolyte is obtained.

8. The electrolyte-resistant modified EPDM rubber according to claim 7, characterized in that, The compatibilizer is maleic anhydride-grafted EPDM; the reinforcing agent is selected from at least one of silica and carbon black; the barrier agent is selected from at least one of organically modified montmorillonite, organically modified kaolinite, and organically modified hydrotalcite; the activator is a mixture of zinc oxide and stearic acid in a mass ratio of 4.5-5.5:0.5-1.5; the vulcanizing agent is selected from at least one of dicumyl peroxide, 1,1-di-tert-butylperoxide-3,3,5-trimethylcyclohexane, and benzoyl peroxide; the co-vulcanizing agent is selected from at least one of triallyl isocyanurate and triallyl cyanurate.

9. The electrolyte-resistant modified EPDM rubber according to claim 7, characterized in that, In step S1, the overall mixing temperature is 100-110℃; in step S2, the temperature of the first vulcanization mixing is 155-165℃, the rotation speed is 60 rpm, and the mixing time is 2-3 min; in step S3, the temperature of the second vulcanization mixing is 150-160℃, and the mixing time is 4-5 min.

10. The electrolyte-resistant modified EPDM rubber according to claim 7, characterized in that, In S4, post-vulcanization involves molding the film at 160-170℃ and 8-12MPa for 10-20 minutes, and heat treatment involves heat-treating the molded product at 140-160℃ for 3-5 hours.

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