Ethylene-propylene-diene monomer rubber compound for high-performance damping sealing element and preparation method of ethylene-propylene-diene monomer rubber compound

Abstract

The invention relates to the field of vinyl rubber materials, in particular to an ethylene propylene diene monomer rubber compound for a high-performance damping sealing element and a preparation method of the ethylene propylene diene monomer rubber compound. The material is composed of the following raw materials in percentage by weight: 45-65% of ethylene propylene diene monomer; 5-10% of a plasticizer; 26-42% of a reinforcing modifier; 1-2% of an accelerant; 0.1 to 0.5 percent of vulcanizing agent; the reinforced modifier is composed of a filler, petroleum resin and a functional aid in a weight ratio of 10: (0.5-2): (1-2.5); the filler is composed of carbon black and aramid short fiber dispersion; the functional auxiliary agent comprises polysiloxane, a functionalized silicon dioxide dispersion material and an ethylene / vinyl acetate / carbon monoxide terpolymer. The filling material, the petroleum resin and the functional additive are compounded and cooperated to stabilize a composite skeleton, so that a product prepared by vulcanizing the final ethylene propylene diene monomer rubber compound has better physical properties and also has better high temperature resistance, compression resistance, medium resistance and the like.

Description

Technical Field

[0001] This application relates to the field of vinyl rubber materials, and in particular to an EPDM rubber compound for high-performance shock-absorbing seals and its preparation method. Background Technology

[0002] Ethylene propylene diene monomer (EPDM) rubber, with its excellent weather resistance, ozone resistance, and chemical stability, has been widely used in high-end fields such as aerospace, new energy vehicles, high-end industrial transmission, petrochemicals, and rail transportation. With the rapid development of high-end equipment manufacturing, new energy vehicles, and rail transportation, more stringent requirements have been placed on the comprehensive performance of EPDM rubber compounds. These industries not only expect EPDM rubber compounds to maintain basic elasticity and aging resistance, but also urgently require significant improvements in their mechanical strength, abrasion resistance, environmental tolerance, and bonding stability with the substrate. During the operation of high-end equipment, EPDM rubber compounds need to withstand high temperatures, long-term compression, and complex media; in the new energy vehicle sector, the requirements for sealing and shock absorption performance are also increasing; and the rail transportation industry has strict standards for the long-term stability and reliability of materials. Therefore, improving the performance of EPDM rubber compounds is crucial for the development of these high-end fields.

[0003] In existing technologies, to enhance the performance of EPDM rubber compounds, methods such as single-agent carbon black filling or simple compounding with conventional inorganic fillers are commonly used. Single-agent carbon black filling is a relatively common approach, as carbon black, a commonly used reinforcing filler in rubber, can improve the performance of the compound to some extent. Existing modification processes also involve adding silane coupling agents for surface modification to improve the compatibility and dispersibility between the filler and rubber, thereby enhancing the physical properties of the compound to some extent. These methods have contributed to improving the performance of EPDM rubber compounds for a period of time, but with the development of the industry, their limitations have gradually become apparent.

[0004] However, existing technologies have significant drawbacks. When using carbon black as a single filler, excessive carbon black content can reduce the fluidity of the rubber compound during processing, and the improvement in mechanical strength is limited, making it difficult to meet the tear resistance requirements of high-end products. Conventional inorganic fillers such as silica have poor compatibility with EPDM, easily leading to agglomeration and uneven compound performance. Traditional additive systems have limited functionality and cannot achieve a synergistic effect of "reinforcement-toughening-stabilization." When products are applied to high-temperature, long-term compression, or complex media environments (such as oily environments), they are prone to aging failure and performance degradation. Even with modification using silane coupling agents, performance improvements are limited, especially in high-end sealing and vibration damping applications, such as high-performance sealing strips, high-temperature and oil-resistant components in engine compartments, and vibration damping components. The performance stability and service life of products made from existing compounded rubbers cannot meet actual requirements. Summary of the Invention

[0005] In order to obtain high mechanical properties, as well as good high temperature resistance, compression resistance, and media resistance, a EPDM rubber compound for high-performance shock-absorbing seals and its preparation method are provided.

[0006] In the first aspect, an EPDM rubber compound for high-performance shock-absorbing seals comprises the following raw materials by weight percentage: 45-65% EPDM rubber; Plasticizer 5-10% 26-42% reinforcing modifier; Accelerator 1-2%; Vulcanizing agent 0.1-0.5%; The reinforcing modifier is composed of fillers, petroleum resin, and functional additives in a weight ratio of 10:(0.5-2):(1-2.5); The filler is composed of a dispersion of carbon black and aramid short fibers; The functional additives include polysiloxanes, functionalized silica dispersions, and ethylene / vinyl acetate / carbon monoxide terpolymers.

[0007] By adopting the above technical solutions, ethylene propylene diene monomer (EPDM) rubber, plasticizer, accelerator, and vulcanizing agent are used to construct a stable basic formulation system, which provides support for the synergistic effect of subsequent functional components; carbon black and aramid short fiber dispersion form a dense cross-linked composite skeleton, laying the foundation for the mechanical properties of the product.

[0008] Based on this, the various functional components and the filling system form a multi-dimensional synergistic effect: Polysiloxanes enhance the thermal stability and ablation resistance of the system. On the other hand, they promote the uniform dispersion of carbon black in the rubber matrix and strengthen the interfacial bonding between carbon black and rubber, thus providing interfacial protection for the reinforcement of the filler skeleton. They form a synergistic system of "dispersion-reinforcement-high temperature resistance" with carbon black and aramid short fiber dispersions.

[0009] Functionalized silica dispersions have a triple effect of reinforcement, interfacial strengthening and compression resistance enhancement. They work synergistically with polysiloxanes to optimize the interfacial bonding between the rubber matrix and the filler, further reducing stress concentration. At the same time, they form a "double reinforcement" synergistic effect with carbon black, significantly improving the physical properties and structural stability of the material.

[0010] Ethylene / vinyl acetate / carbon monoxide terpolymer (EVA-CO) plays a role in compatibilization and media resistance optimization. When combined with polysiloxane and functionalized silica dispersion, it forms a synergistic system of "interface regulation-dispersion optimization-performance improvement": it not only improves the dispersion uniformity of each component (especially fillers and rubber matrix), but also enhances the resistance of the compound to media, while also helping to enhance the elasticity and toughness of the material. Together with the former two, it solves the technical pain points of uneven filler dispersion and weak interfacial bonding.

[0011] In summary, the core of this application is to form a synergistic system through the ternary compounding of polysiloxane, functionalized silica dispersion, and EVA-CO. This system, together with the filler (carbon black + aramid short fiber dispersion) and petroleum resin, further forms a multi-layered synergistic effect of "functional component - filler system - tackifying component": on the one hand, it synergistically stabilizes the composite skeleton structure, strengthens the bonding stability of the entire raw material system, and avoids the performance shortcomings under the action of a single component; on the other hand, it achieves the simultaneous synergistic improvement of physical properties (mechanical strength, elasticity, toughness) and high temperature resistance, compression resistance, and media resistance, breaking through the limitations of traditional EPDM rubber compounds that are "excellent in a single property but unbalanced in comprehensive performance", ultimately enabling the product to fully meet the stringent requirements of high-end sealing and vibration damping scenarios for the comprehensive performance of materials.

[0012] Preferably, the petroleum resin is one or a combination of multiple of the following: C5 / C9 copolymer petroleum resin, hydrogenated petroleum resin, maleic anhydride modified petroleum resin, and terpene-phenolic petroleum resin.

[0013] C5 / C9 copolymer petroleum resins can improve the viscosity and processing fluidity of rubber compounds, enhance the stability of carbon black-aramid short fiber composite skeletons, and improve the tensile strength and thermal stability of products; hydrogenated petroleum resins can improve high-temperature resistance, aging resistance, and media resistance, and improve the low-temperature resilience of EPDM rubber compounds; maleic anhydride modified petroleum resins can react with functionalized silica dispersants to improve the dispersion of fibers in the rubber matrix and reduce the permanent deformation of products under long-term compression cycles; terpene-phenolic petroleum resins can form hydrogen bond networks, inhibit the thermo-oxidative aging of EPDM molecular chains, improve the hardness, abrasion resistance, and tear resistance of materials, and extend the service life of products.

[0014] Preferably, the petroleum resin is composed of C5 / C9 copolymer petroleum resin, hydrogenated petroleum resin, maleic anhydride modified petroleum resin, and terpene-phenolic petroleum resin.

[0015] Furthermore, the petroleum resin is composed of C5 / C9 copolymer petroleum resin, hydrogenated petroleum resin, maleic anhydride modified petroleum resin, and terpene-phenolic petroleum resin in a weight ratio of 1:(0.2-0.45):(1-3):(1-2).

[0016] By adopting the above technical solution, C5 / C9 copolymer petroleum resin, hydrogenated petroleum resin, maleic anhydride modified petroleum resin, and terpene-phenolic petroleum resin are compounded in a weight ratio of 1:(0.2-0.45):(1-3):(1-2), which can achieve a synergistic effect and further improve the comprehensive performance of EPDM rubber compound.

[0017] Specifically, the active groups in the composite petroleum resin system (such as the anhydride groups in maleic anhydride-modified petroleum resin and the phenolic hydroxyl groups in terpene-phenolic petroleum resin) undergo cross-linking reactions with the active sites (such as double bond addition products and free radicals) formed by the EPDM molecular chain during vulcanization. At the same time, they work together with the active groups of functional additives (such as the hydroxyl groups in functionalized silica dispersions and the siloxane bonds in polysiloxanes) to construct a three-dimensional cross-linking network, thereby enhancing the structural stability of the EPDM matrix. The compatibility advantage of hydrogenated petroleum resin and EPDM ensures that the synergistic system forms a continuous phase structure with the rubber matrix, avoiding interface defects. The tackifying effect of the composite petroleum resin and the reinforcing effect of the functional additives are superimposed, which significantly improves the mechanical properties (elongation at break, tear strength, elastic recovery rate) of the EPDM matrix. The aforementioned multiple synergistic effects ultimately enable the physical properties of EPDM rubber compound to achieve a simultaneous leap in high temperature resistance, compression set resistance, and media resistance (oil resistance and aging media resistance), breaking through the limitations of traditional single petroleum resin or single functional additive modification, and constructing an integrated and stable structure of "matrix-skeleton-additive-resin".

[0018] In summary, this application achieves synergistic reinforcement of the carbon black-aramid short fiber composite skeleton through precise compounding of the composite petroleum resin system and functional additives, and forms deep bonding and structural complementarity with the EPDM matrix. Ultimately, this results in a compound with excellent comprehensive performance, fully meeting the stringent requirements of high-end sealing and vibration damping applications for material mechanical strength, stability, and resistance to environmental media.

[0019] Preferably, the functionalized silica dispersion is an organically functionalized silane-functionalized nano-sized SiO2 particles and / or a silica-trimethylolpropane triacrylate nanocomposite dispersion.

[0020] By adopting the above technical solution, organically functionalized silane-functionalized nano-sized SiO2 particles and / or silica-trimethylolpropane triacrylate nanocomposite dispersion are used as functionalized silica dispersions. These dispersions form a synergistic system with EPDM rubber, petroleum resin, carbon black-aramid short fiber dispersion, polysiloxane, and ethylene / vinyl acetate / carbon monoxide terpolymer, resulting in EPDM rubber compound products with excellent tensile strength, tear strength, and elastic recovery. The active groups of the silane-functionalized nano-sized SiO2 particles react with the active groups of the EPDM rubber molecular chains, and the amino groups form hydrogen bonds with the carboxyl groups of the petroleum resin, preventing filler agglomeration. The nano-sized particles fill the carbon black-aramid short fiber composite... The micropores in the composite skeleton enhance the material's mechanical strength and resistance to deformation, while the silane functional groups strengthen the material's resistance to damp heat aging. During the vulcanization process, TMPTA in the silica-trimethylolpropane triacrylate nanocomposite dispersion undergoes a free radical copolymerization reaction with the carbon-carbon double bonds of the EPDM rubber matrix and polysiloxane, strengthening the stability of the carbon black-aramid short fiber composite skeleton. The ester groups of TMPTA form a compatible interface with the polar groups of the E / VAC / CO terpolymer, improving the compatibility between the inorganic filler and the organic matrix, reducing stress concentration, and enhancing the material's resistance to media penetration. This allows the product to exhibit superior tolerance under high temperature, long-term compression cycles, and complex media environments, significantly improving its adaptability in demanding scenarios such as high-end sealing and vibration damping.

[0021] Preferably, the polysiloxane is an oligomeric polysiloxane containing vinyl, propyl, and ethoxy groups.

[0022] By adopting the above technical solution, the low-polysiloxane containing vinyl, propyl, and ethoxy groups, along with functionalized silica dispersions and ethylene / vinyl acetate / carbon monoxide terpolymers, can significantly improve the compatibility between fillers and petroleum resins in EPDM rubber compounds. This, in turn, synergistically enhances the physical properties, high-temperature resistance, compression resistance, and media resistance of the vulcanized rubber compound. The ethoxy and vinyl groups of the polysiloxane can form binding points with the surface-active groups of the functionalized silica dispersions, achieving uniform dispersion and stable bonding of fillers and petroleum resins within the system.

[0023] Preferably, the aramid short fiber dispersion is an aramid short fiber EPDM dispersion, or is composed of an aramid short fiber EPDM dispersion and an aramid short fiber MBR dispersion.

[0024] By adopting the above technical solution, using aramid short fiber EPDM dispersion or a mixture of aramid short fiber MBR dispersion as the aramid short fiber dispersion, combined with the synergistic effect of petroleum resin and functional additives (vinyl / propyl / ethoxy oligosiloxane, functionalized silica dispersion, ethylene / vinyl acetate / carbon monoxide terpolymer), the raw material system of EPDM rubber compound can be significantly optimized. When aramid short fiber EPDM dispersion and aramid short fiber MBR dispersion are compounded, they can also play a reinforcing role, further improving the synergistic effect and oil resistance.

[0025] Meanwhile, EPDM rubber, plasticizer, accelerator, and vulcanizing agent form the basic formula. Carbon black and aramid short fiber dispersion in the filler form a dense cross-linked composite skeleton, improving the mechanical properties of the EPDM rubber compound after vulcanization. Polysiloxane in the functional additives enhances the thermal stability and ablation resistance of the system and promotes carbon black dispersion. Functionalized silica dispersion has multiple functions, including reinforcement, enhancing interfacial bonding, and improving compression resistance. Ethylene / vinyl acetate / carbon monoxide terpolymer plays a role in compatibilization, improving interfacial compatibility, and optimizing media resistance. The three components work synergistically to stabilize the composite skeleton, so that the final EPDM rubber compound, after vulcanization, not only has good physical properties but also good high-temperature resistance, compression resistance, and media resistance, improving its adaptability in high-end applications such as high-end sealing and vibration damping.

[0026] Preferably, the weight ratio of the aramid short fiber EPDM dispersion to the aramid short fiber MBR dispersion is 1:(3-4).

[0027] By adopting the above technical solution, carbon black is compounded as a filler using aramid short fiber EPDM dispersion and aramid short fiber MBR dispersion in a weight ratio of 1:(3-4). Combined with the synergistic effect of petroleum resin and functional additives (vinyl / propyl / ethoxy oligosiloxane, functionalized silica dispersion, ethylene / vinyl acetate / carbon monoxide terpolymer), the raw material system of EPDM rubber compound can be significantly optimized, playing a reinforcing role, further improving the synergistic effect, and enhancing oil resistance. Simultaneously, in conjunction with the basic formulation consisting of EPDM rubber, plasticizer, accelerator, and vulcanizing agent, carbon black and aramid short fiber dispersion form a dense cross-linked composite skeleton. The functional additives stabilize this skeleton, enabling EPDM rubber compound products to possess both excellent physical properties and high-temperature resistance, compression resistance, and media resistance, meeting the stringent requirements of high-end sealing and vibration damping applications.

[0028] Preferably, the weight ratio of the carbon black and aramid short fiber dispersion is 10:(2-5).

[0029] By adopting the above technical solution, carbon black and aramid short fiber dispersions are constructed in this weight ratio to form a dense cross-linked composite skeleton. Carbon black forms the basic support network, and the aramid short fibers and carbon black network are intertwined and entangled. This can further improve the mechanical properties of EPDM rubber compound after vulcanization. At the same time, this ratio is also part of the efficient synergy of the components in the reinforcing modifier. It enables the EPDM rubber compound to maintain good processing performance and suitable softness after vulcanization, improve physical and mechanical properties such as tensile strength and tear strength, optimize high temperature stability, compression resistance and resistance to media erosion, and comprehensively improve the shock absorption and sealing effect and service life of EPDM products.

[0030] Preferably, the accelerator is one or a combination of N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, 2-thiol-benzothiazole, and dibenzothiazole disulfide; the vulcanizing agent is dicumyl peroxide and / or 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; and the plasticizer is one or a combination of liquid polybutadiene, a liquid copolymer of low molecular weight butadiene and styrene, and trioctyl phosphate.

[0031] By adopting the above technical solution and using a specific combination of accelerators, vulcanizing agents, and plasticizers, the plasticizer can improve processing fluidity, adjust the softness of the vulcanized rubber, and enhance component compatibility. The accelerator and vulcanizing agent can enable the EPDM rubber compound to complete the vulcanization process. Furthermore, the reinforcing modifier and plasticizer form a "synergistic and complementary" relationship. After vulcanization, the EPDM rubber compound maintains good processing performance and suitable softness, and its physical and mechanical properties such as elongation at break and tear strength are improved. Its high-temperature stability, compression resistance, and resistance to media erosion are significantly optimized, further enhancing the shock absorption and sealing effect and service life of EPDM products.

[0032] Secondly, an EPDM rubber compound for high-performance shock-absorbing seals is obtained by the following method: Weigh out EPDM rubber by weight percentage, heat and plasticize it evenly, then add plasticizer and mix evenly, then add reinforcing modifier in batches and mix evenly, then add accelerator after cooling and mix evenly, and finally add vulcanizing agent and mix evenly to obtain EPDM rubber compound.

[0033] By adopting the above technical solution and forming the reinforcing modifier according to this weight ratio, the filler, petroleum resin and functional additives can achieve efficient synergy. The filler constructs the mechanical skeleton of the EPDM vulcanizate, the petroleum resin enhances the interfacial bonding force between the filler and the rubber matrix, and the functional additives solve the compatibility problem between the filler and the petroleum resin and EPDM, so that the filler can be uniformly dispersed at the nanoscale in the system, maximizing the reinforcing effect. In the end, the EPDM rubber compound not only maintains good processing performance and suitable softness, but also improves physical and mechanical properties such as elongation at break and tear strength, optimizes high temperature stability, compression resistance and resistance to media erosion, and comprehensively improves the performance and service life of EPDM products.

[0034] EPDM rubber, plasticizer, reinforcing modifier, accelerator, and vulcanizing agent are weighed and mixed evenly according to the weight percentage to obtain EPDM rubber compound. The plasticizer can improve processing fluidity, adjust the softness of the vulcanized rubber, and improve the compatibility of components. The filler in the reinforcing modifier builds a mechanical skeleton, the petroleum resin enhances the interfacial bonding force, and the functional additives solve the compatibility problem, so that the compound maintains good processing performance and suitable softness, and improves physical and mechanical properties, high temperature stability, compression resistance and resistance to media erosion.

[0035] In summary, this application includes at least one of the following beneficial technical effects: 1. Carbon black and aramid short fiber dispersions form a dense cross-linked composite skeleton, which improves the mechanical properties of EPDM rubber compound after vulcanization. 2. Polysiloxanes improve the thermal stability and ablation resistance of the system, avoid phase separation problems, promote the uniform dispersion of carbon black in the rubber matrix, and enhance the interfacial bonding force between carbon black and rubber; 3. Functionalized silica dispersions have multiple functions, including reinforcement, enhancing interfacial bonding, and improving compressibility, reducing stress concentration and improving the tensile strength, tear strength, and other physical properties of the material. 4. The ethylene / vinyl acetate / carbon monoxide terpolymer plays a role in compatibilizing, improving interfacial compatibility and optimizing media resistance, improving the dispersion uniformity of each component, and enhancing the resistance of EPDM rubber compound to various media. 5. Plasticizers improve processing fluidity, adjust the softness of vulcanized rubber, and enhance component compatibility, making it easier for solid components such as reinforcing modifiers to disperse evenly and precisely control the hardness and elasticity of the final EPDM product. Detailed Implementation

[0036] The present application will be further described in detail below with reference to the embodiments.

[0037] Introduction to some raw materials: Ethylene propylene diene monomer (EPDM) rubber: Mitsui Chemicals 8120E (Japan); Ethylene / vinyl acetate / carbon monoxide terpolymer: ELVALOY™ 741; Oligomeric siloxanes containing vinyl, propyl, and ethoxy groups: Dynasylan® 6598; Organically functionalized silane-functionalized nano-sized SiO2 particles: Dynasylan® SIVO110; Silica-trimethylolpropane triacrylate nanocomposite dispersion: NANOCRYL® C150; Carbon black: Yiborui N770 carbon black; C5 / C9 copolymer petroleum resin: Eastotac™ H100E (CAS No.: 68441-58-1); Hydrogenated petroleum resin: Arkon® P140 (CAS No.: 64742-16-1). Maleic anhydride modified petroleum resin: Escorez® 5600 (CAS No.: 68515-71-5); Terpene-phenolic petroleum resin: Hercules® Piccotac™ 115 (CAS No.: 68442-53-5); Aramid short fiber EPDM dispersion: Rheinland P91-40 / EPDM; Aramid short fiber MBR dispersion: Rheinland P91-40 / NBR; Cyclohexyl-2-benzothiazole sulfenamide: CAS No. 95-33-0; tert-Butyl-2-benzothiazole sulfenamide CAS No. 95-31-8; Thiol-based benzothiazole: CAS No. 149-30-4; Dibenzothiazole disulfide: CAS No. 120-78-5; Liquid polybutadiene: Krevili Ricon 300; Liquid copolymer of low molecular weight butadiene and styrene: Clayville plasticizer Ricon181. Example

[0038] Example 1 An EPDM rubber compound for high-performance shock-absorbing seals is obtained by the following method: The petroleum resin is composed of C5 / C9 copolymer petroleum resin and maleic anhydride modified petroleum resin in a weight ratio of 1:1.

[0039] Reinforcing modifier: Weigh the filler, petroleum resin, and functional additives and place them in a stirring device. Stir at 200 r / min for 30 min to obtain the reinforcing modifier. The weight ratio of filler, petroleum resin, and functional additives is 10:0.5:2.5.

[0040] The filler is composed of carbon black and aramid short fiber dispersion (aramid short fiber EPDM dispersion) in a weight ratio of 10:2. The functional additives are composed of polysiloxane, functionalized silica dispersion, and ethylene / vinyl acetate / carbon monoxide terpolymer in a weight ratio of 1:2:1.

[0041] The functionalized silica dispersion is an organically functionalized silane-functionalized nano-sized SiO2 particle; the polysiloxane is an oligomeric siloxane containing vinyl, propyl and ethoxy groups.

[0042] First stage of mixing: Turn on the internal mixer, set the temperature to 95℃ and the speed to 60r / min, add EPDM rubber, and plasticize for 5 minutes until the rubber compound is uniform; add plasticizer, mix for 2 minutes, and then add reinforcing modifier in 3 batches, each batch mixing for 10 minutes, during which the temperature of the rubber compound is monitored to not exceed 100℃, and discharge the rubber to obtain the first stage of mixed rubber.

[0043] Two-stage mixing: Reduce the temperature of the internal mixer to 60℃, add the first-stage compound, and mix for 3 minutes; then add the accelerator and continue mixing for 5 minutes; finally add the vulcanizing agent and mix quickly for 2 minutes (keeping the temperature below 75℃ to avoid scorching), and discharge the compound.

[0044] Post-processing: The two-stage compound was passed through an open mixing mill 5 times (roll gap 0.5mm), then sheeted (thickness 2mm) and left at room temperature for 4 hours to obtain a high-performance EPDM rubber compound.

[0045] The accelerator is N-cyclohexyl-2-benzothiazole sulfenamide; the vulcanizing agent is 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (bis25 vulcanizing agent); the plasticizer is composed of liquid polybutadiene, a liquid copolymer of low molecular weight butadiene and styrene, and trioctyl phosphate in a weight ratio of 1:1:2.

[0046] The raw material usage for Example 1 is detailed in Table 1.

[0047] Example 2-3 The difference between Examples 2-3 and Example 1 lies in the amount of raw materials used, as shown in Table 1. Table 1. Raw material usage (kg) for Examples 1-3 Example

[0048] The difference between Example 4 and Example 2 is that the petroleum resin is maleic anhydride modified petroleum resin.

[0049] Example 5 The difference between Example 5 and Example 2 is that the petroleum resin is composed of C5 / C9 copolymer petroleum resin and hydrogenated petroleum resin in a weight ratio of 1:1.

[0050] Example 6 The difference between Example 6 and Example 2 is that the petroleum resin is composed of C5 / C9 copolymer petroleum resin, hydrogenated petroleum resin, and terpene-phenolic petroleum resin in a weight ratio of 1:0.5:0.5.

[0051] Example 7 The difference between Example 7 and Example 2 is that the petroleum resin is composed of C5 / C9 copolymer petroleum resin, hydrogenated petroleum resin, maleic anhydride modified petroleum resin, and terpene-phenolic petroleum resin in a weight ratio of 1:0.25:0.5:0.25.

[0052] Example 8 The difference between Example 8 and Example 2 is that the functionalized silica dispersion is a silica-trimethylolpropane triacrylate nanocomposite dispersion.

[0053] Example 9 The difference between Example 9 and Example 2 is that the functionalized silica dispersion is composed of organically functionalized silane-functionalized nano-sized SiO2 particles and silica-trimethylolpropane triacrylate nanocomposite dispersion in a weight ratio of 3:1.

[0054] Example 10 The difference between Example 10 and Example 7 is that the functionalized silica dispersion is composed of organically functionalized silane-functionalized nano-sized SiO2 particles and silica-trimethylolpropane triacrylate nanocomposite dispersion in a weight ratio of 3:1.

[0055] Example 11 The difference between Example 11 and Example 2 is that the aramid short fiber dispersion is composed of aramid short fiber EPDM dispersion and aramid short fiber MBR dispersion in a weight ratio of 1:4.

[0056] Example 12 The difference between Example 12 and Example 10 is that the aramid short fiber dispersion is composed of aramid short fiber EPDM dispersion and aramid short fiber MBR dispersion in a weight ratio of 1:4.

[0057] Example 13 The difference between Example 13 and Example 10 is that the aramid short fiber dispersion is composed of aramid short fiber EPDM dispersion and aramid short fiber MBR dispersion in a weight ratio of 1:3.

[0058] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 2 is that the functional additives were replaced with fillers in equal amounts.

[0059] Comparative Example 2 The difference between Comparative Example 2 and Example 2 is that the functional additives were replaced with an equal amount of silane coupling agent KH530.

[0060] Comparative Example 3 The difference between Comparative Example 3 and Example 2 is that the functional additive is polysiloxane.

[0061] Comparative Example 4 The difference between Comparative Example 4 and Example 2 is that the aramid short fiber dispersion was replaced with an equal amount of carbon black.

[0062] Comparative Example 5 The difference between Comparative Example 5 and Example 2 is that the reinforcing modifier is composed of carbon black and petroleum resin in a weight ratio of 10:3.

[0063] Performance testing Sample preparation: Weigh the EPDM rubber compounds obtained in Examples 1-13 and Comparative Examples 1-5 according to the corresponding weight, place them into a mold, and then transfer the mold to a flat vulcanizing machine. Vulcanize for 8 minutes at a temperature of 155℃ and a pressure of 30MPa. After removing the mold, allow it to cool naturally to 30℃ at room temperature, demold, and cut the sample to obtain several samples for the following experimental tests.

[0064] Test methods 1) Resilience: Refer to ASTM D2632; use a rebound pendulum tester. Drop a pendulum from a specified height to impact the sample and measure the percentage of the rebound height to the drop height. When the rebound value is ≥56%, it is considered qualified.

[0065] 2) Tear strength: Refer to ASTM D624 (DieC); use a right-angled specimen and stretch it at a constant speed on a tensile testing machine until it tears. Calculate the maximum tear force and divide it by the specimen thickness. When the tear strength is ≥45kN / m, it is considered qualified.

[0066] 3) Elongation at break: Refer to ASTM D412; use dumbbell-shaped specimens, stretch them to break on a tensile testing machine, record the change in length at break, calculate the percentage relative to the original gauge length, and when the elongation at break is ≥480%, it is considered acceptable.

[0067] When all of 1)-3) are qualified, the mechanical properties are considered qualified.

[0068] 4) High temperature and high humidity aging: Refer to ASTM D573; place the sample in a controllable constant temperature and humidity chamber, such as at 125℃ and 85% relative humidity, set the time to 168h, take it out and cool it to room temperature, and test the retention rate of its elongation at break.

[0069] 5) Compression retention: Refer to ASTM D395 Method B (Constant Deformation Compression Test Method): Prepare a standard cylindrical rubber specimen and accurately measure the original height t0 of the specimen (take the arithmetic mean of 3 different measuring points); use a rigid compression clamp and a gasket with a thickness of ts=0.75t0 to compress the specimen to a constant deformation of 25% to ensure that the clamp does not loosen or deform during the test; Place the assembled sample-fixture assembly into an oven and maintain it at a constant temperature of 125℃ for 24 hours. After the time is reached, remove the component and unload it in an environment with a room temperature of 25℃ and a relative humidity of 55%, allowing the sample to relax and recover for 30 minutes; then accurately measure the height t1 of the sample after recovery (the measurement position corresponds one-to-one with the original height measurement point). According to the formula: Compression retention rate = (t1 / t0) × 100% The calculation results and the experimental results are the average values ​​of three parallel samples.

[0070] 6) Oil resistance: Refer to ASTM D471; immerse the sample in the specified type of oil (IRM903 oil) at 100°C for 72 hours. After removal, clean and dry, measure the volume, and calculate the volume expansion rate, which is equal to [(volume after test - volume before test) / volume before test] × 100%.

[0071] The specific experimental data are shown in Table 2. Table 2. Experimental data of Examples 1-13 and Comparative Examples 1-5

[0072] Combining Example 2 and Comparative Examples 1-5 with Table 2, it can be seen that the mechanical properties of Comparative Examples 1 and 3-5 are all unqualified. After high temperature and high humidity aging, compression set, and oil resistance tests, their elongation at break retention rate is less than 81%, compression retention rate is less than 80%, and volume expansion rate is greater than 10%. In contrast, Example 2 has a rebound value ≥58%, tear strength ≥45kN / m, elongation at break ≥450%, and a elongation at break retention rate of 85.8%, a compression retention rate of 83.6%, and a volume expansion rate of only 6.2%. This indicates that the present application uses a reinforcing modifier consisting of fillers (carbon black and aramid short fiber dispersion), petroleum resin, and functional additives (polysiloxane, functionalized silica dispersion, ethylene / vinyl acetate / carbon monoxide terpolymer) to further improve the physical properties, high temperature resistance, compression resistance, and media resistance of the EPDM rubber compound after vulcanization.

[0073] Combining Examples 2 and 4-7 with Table 2, it can be seen that the retention rates of elongation at break and compression ratios in Examples 2 and 4-6 are lower than those in Example 7, while the volume expansion rates are higher. This indicates that the use of petroleum resins, which are a blend of C5 / C9 copolymer petroleum resin, hydrogenated petroleum resin, maleic anhydride modified petroleum resin, and terpene-phenolic petroleum resin, has a synergistic effect, further improving the overall performance of the EPDM rubber compound after vulcanization.

[0074] Based on Examples 2 and 7-10 and Table 2, it can be seen that the retention rates of elongation at break and compression ratios in Examples 2 and 7-9 are lower than those in Example 10, while the volume expansion rates are higher. This indicates that the combination of organically functionalized silane-functionalized nano-sized SiO2 particles and silica-trimethylolpropane triacrylate nanocomposite dispersion has a synergistic effect, further improving the physical properties, high-temperature resistance, compression resistance, and media resistance of the EPDM rubber compound after vulcanization.

[0075] Based on Examples 2 and 11-12 and Table 2, it can be seen that the retention rates of elongation at break and compression ratios in Examples 2 and 11 are lower than those in Example 12, while the volume expansion rates are higher. This indicates that the compounding of aramid short fiber EPDM dispersion and aramid short fiber MBR dispersion has a synergistic effect, further improving the physical properties, high temperature resistance, compression resistance, and media resistance of the EPDM rubber compound after vulcanization.

[0076] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A EPDM rubber compound for high-performance shock-absorbing seals, characterized in that, It consists of the following raw materials by weight percentage: 45-65% EPDM rubber; Plasticizer 5-10% 26-42% reinforcing modifier; Accelerator 1-2%; Vulcanizing agent 0.1-0.5%; The reinforcing modifier is composed of fillers, petroleum resin, and functional additives in a weight ratio of 10:(0.5-2):(1-2.5); The filler is composed of a dispersion of carbon black and aramid short fibers; The functional additives include polysiloxanes, functionalized silica dispersions, and ethylene / vinyl acetate / carbon monoxide terpolymers.

2. The EPDM rubber compound for high-performance shock-absorbing seals according to claim 1, characterized in that: The petroleum resin is one or a combination of multiple of the following: C5 / C9 copolymer petroleum resin, hydrogenated petroleum resin, maleic anhydride modified petroleum resin, and terpene-phenolic petroleum resin.

3. The EPDM rubber compound for high-performance shock-absorbing seals according to claim 2, characterized in that: The petroleum resin is composed of C5 / C9 copolymer petroleum resin, hydrogenated petroleum resin, maleic anhydride modified petroleum resin, and terpene-phenolic petroleum resin.

4. The EPDM rubber compound for high-performance shock-absorbing seals according to claim 1, characterized in that: The functionalized silica dispersion is an organically functionalized silane-functionalized nano-sized SiO2 particles and / or a silica-trimethylolpropane triacrylate nanocomposite dispersion.

5. The EPDM rubber compound for high-performance shock-absorbing seals according to claim 1, characterized in that: The polysiloxane is an oligomeric polysiloxane containing vinyl, propyl, and ethoxy groups.

6. The EPDM rubber compound for high-performance shock-absorbing seals according to claim 1, characterized in that: The aramid short fiber dispersion is an aramid short fiber EPDM dispersion, or is composed of an aramid short fiber EPDM dispersion and an aramid short fiber MBR dispersion.

7. The EPDM rubber compound for high-performance shock-absorbing seals according to claim 6, characterized in that: The weight ratio of the aramid short fiber EPDM dispersion to the aramid short fiber MBR dispersion is 1:(3-4).

8. The EPDM rubber compound for high-performance shock-absorbing seals according to claim 1, characterized in that: The weight ratio of the carbon black and aramid short fiber dispersion is 10:(2-5).

9. The EPDM rubber compound for high-performance shock-absorbing seals according to claim 1, characterized in that: The accelerator is one or more of N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, 2-thiol-benzothiazole, and dibenzothiazole disulfide; the vulcanizing agent is dicumyl peroxide and / or 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; and the plasticizer is one or more of liquid polybutadiene, a liquid copolymer of low molecular weight butadiene and styrene, and trioctyl phosphate.

10. A method for preparing a EPDM rubber compound for high-performance shock-absorbing seals as described in any one of claims 1-9, characterized in that, Obtained by the following method: Weigh out EPDM rubber by weight percentage, heat and plasticize it evenly, then add plasticizer and mix evenly, then add reinforcing modifier in batches and mix evenly, then add accelerator after cooling and mix evenly, and finally add vulcanizing agent and mix evenly to obtain EPDM rubber compound.

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