High-tensile wear-resistant high-temperature-resistant sealing ring and preparation method thereof

Abstract

The invention relates to the technical field of sealing rings, in particular to a high-tensile wear-resistant high-temperature-resistant sealing ring and a preparation method thereof. The high-tensile wear-resistant high-temperature-resistant sealing ring is prepared from the following raw materials in parts by mass: 60 to 65 parts of fluorocarbon elastomer, 10 to 13 parts of methyl vinyl silicone rubber, 25 to 30 parts of modified silicon carbide, 8 to 11 parts of modified glass fiber, 1 to 2 parts of zinc oxide, 2 to 3 parts of zinc stearate, 1 to 1.5 parts of antioxidant and 2 to 4 parts of vulcanizing agent. Through a synergistic mechanism of'rigid filler + hydrogen bond network + chemical bonding ', the performance limitation of a single material is broken through, the comprehensive performance improvement of high strength, high wear resistance and high temperature resistance is realized, and the extreme working condition requirements in the fields of aerospace, automobile industry, petrochemical equipment and the like can be met.

Description

Technical Field

[0001] This application relates to the technical field of sealing rings, and particularly relates to a high-tensile-strength, wear-resistant, and high-temperature-resistant sealing ring and a preparation method thereof. Background Art

[0002] Traditional sealing rings are mostly made of rubber materials, which have low cost but poor heat resistance. They are prone to aging and deformation under high temperature and pressure, resulting in sealing failure. Existing improvement solutions such as high-performance polymers (such as PTFE) can improve heat resistance, but they have high costs, complex processing, and their performance drops sharply at extreme temperatures. Some studies have enhanced the performance by adding nano-fillers (such as carbon fibers), but the dispersibility is poor, resulting in insufficient material uniformity. Therefore, there is an urgent need for a high-performance sealing ring with controllable cost, high tensile strength, high wear resistance, and high temperature resistance. Summary of the Invention

[0003] The purpose of this application is to provide a high-tensile-strength, wear-resistant, and high-temperature-resistant sealing ring and a preparation method thereof in view of the deficiencies of the current technology. The high-tensile-strength, wear-resistant, and high-temperature-resistant sealing ring prepared by this application has excellent tensile strength, wear resistance, and heat resistance, effectively ensuring its quality.

[0004] In the first aspect, this application provides a high-tensile-strength, wear-resistant, and high-temperature-resistant sealing ring, adopting the following technical solution: A high-tensile-strength, wear-resistant, and high-temperature-resistant sealing ring, by mass fraction, comprises the following preparation raw materials: 60 - 65 parts of fluorocarbon elastomer, 10 - 13 parts of methyl vinyl silicone rubber, 25 - 30 parts of modified silicon carbide, 8 - 11 parts of modified glass fiber, 1 - 2 parts of zinc oxide, 2 - 3 parts of zinc stearate, 1 - 1.5 parts of antioxidant, and 2 - 4 parts of vulcanizing agent.

[0005] By adopting the above technical solutions, the fluorocarbon elastomer is used as the matrix material. With its carbon-fluorine chain structure, the fluorocarbon elastomer provides high temperature resistance, chemical corrosion resistance (resistance to erosion by media such as oil, acid, and alkali), and a low friction coefficient (reducing the movement wear of the sealing ring). It forms a composite matrix with methyl vinyl silicone rubber, expanding the temperature resistance range (-50°C to 250°C) through physical entanglement between molecular chains, and at the same time providing chemical anchoring points for the modified filler. Methyl vinyl silicone rubber makes up for the low temperature brittleness of the fluorocarbon elastomer and improves the dynamic sealing performance. The silicone oxygen main chain provides high temperature thermal oxidation stability. It forms an interpenetrating network (IPN) structure with the fluorocarbon elastomer, and through the van der Waals force between polar groups and the fluorocarbon chain, it realizes the mechanical properties of combining rigidity and flexibility. After the modified silicon carbide is surface grafted with a silicone oxygen alkane coupling agent containing a naphthalene ring: the aromatic structure of the naphthalene ring restricts the movement of rubber segments, and the double bond of the coupling agent is covalently bonded to the fluorocarbon elastomer, reducing interface defects. Nano-scale dispersion forms a micro-convex body support structure, improving wear resistance and temperature resistance. The modified glass fiber constructs a hydrogen bond cross-linking network through thiol-ene click chemistry: the tensile strength is increased by more than 19 MPa, the dissociation of hydrogen bonds absorbs heat and delays thermal decomposition. It forms a multi-dimensional reinforcement system with silicon carbide: silicon carbide bears the radial stress, and glass fiber resists the axial tensile stress. Zinc oxide: provides Zn 2 + coordinates with the carboxyl group of the rubber to accelerate the vulcanization cross-linking density. Zinc stearate: lubricates and disperses the filler, and at the same time regulates the vulcanization rate. The antioxidant improves the anti-aging ability of the material. The vulcanizing agent realizes the synchronous vulcanization of the fluorocarbon elastomer and the silicone rubber. In short, by adding modified silicon carbide and modified glass fiber to form a bionic "reinforced concrete" structure, the tensile strength breaks through 22 MPa. A triple thermal protection system is constructed through the hydrogen bond network (endothermic) + naphthalene ring rigid structure (heat insulation) + high thermal conductivity filler (heat dissipation), and the continuous use temperature reaches 250°C. Through the construction of a chemical-physical dual interface combination by the silane coupling agent, the bonding strength between the filler and the matrix is significantly improved, and the wear volume < 65 mm 3 . This formulation realizes a breakthrough improvement in the performance of the sealing material through molecular-level structure design and multi-scale reinforcement strategies.

[0006] Preferably, the preparation method of the modified silicon carbide is as follows. By mass, in a nitrogen atmosphere, 20 parts of silicon carbide with a particle size of 50 - 80 nm and 200 parts of deionized water are added to the reactor. It is stirred at a stirring speed of 800 rpm for 1 - 2 h, and after standing for 24 h, 2 - 2.2 parts of dodecyl trimethyl ammonium bromide and 0.5 - 0.7 parts of modified silicone oxygen alkane coupling agent are added, and the reaction is carried out at 90 - 95°C for 6 - 7 h. It is washed with deionized water until no precipitate is detected by silver nitrate, filtered and dried to obtain the modified silicon carbide.

[0007] By adopting the above technical solutions, deionized water dispersion: Uniform dispersion of silicon carbide (50 - 80 nm) is achieved through high-speed stirring (800 rpm), and standing for 24 h can be used to remove undispersed particles or surface impurities. Adding quaternary ammonium salt (dodecyltrimethylammonium bromide): As a cationic surfactant, it adsorbs on the surface of silicon carbide, improves its lipophilicity, and promotes the grafting of subsequent coupling agents. Introducing a modified siloxane coupling agent: Through the reaction of the siloxane group (-Si-OCH3) with the hydroxyl group (-OH) on the surface of silicon carbide, chemical bonding is formed. The 2-hydroxy-6-naphthoic acid in the coupling agent provides a rigid aromatic ring to enhance heat resistance; vinylmethyldifluorosilane introduces an unsaturated double bond for easy cross-linking with fluorocarbon elastomers. Washing until there is no residual bromide ion: Detect Br- with silver nitrate (if precipitation occurs, continue washing) to avoid the influence of residual ions on material stability. Drying to obtain uniformly modified silicon carbide particles. The role of the prepared modified silicon carbide in the sealing ring: 1) Improvement of interfacial compatibility, covalent cross-linking occurs between the unsaturated double bonds in the coupling agent and the double bonds of the fluorocarbon elastomer, reducing interfacial defects. After modification, silicon carbide is dispersed in the rubber matrix at the nanoscale, forming a dense network structure that restricts the slippage of molecular chains. 2) Enhancement of properties, wear resistance: The high hardness of silicon carbide (Mohs hardness 9.5) and the nanoscale dispersion structure jointly resist friction and wear. High temperature resistance: The aromatic ring structure of the coupling agent improves thermal stability (decomposition temperature > 300 °C). Cross-linked network: Restricts the thermal movement of molecular chains and delays the softening of the material at high temperatures. Mechanical properties: Improve tensile strength and tear resistance through physical cross-linking points (hydrogen bonds, chemical bonds). Synergy with fluorocarbon elastomers: Fluorocarbon chains provide chemical corrosion resistance, and silicon carbide enhances rigidity, forming a "rigid-flexible combination" structure. Double bond cross-linking forms a through-network, simultaneously improving wear resistance and tensile strength. Synergy with modified glass fibers, mechanical complementarity: Glass fibers provide an aspect ratio enhancement effect, and silicon carbide fills microscopic voids to form a multi-scale reinforcement system. Heat resistance synergy: The endothermic hydrogen bonds of glass fibers and the rigid structure of silicon carbide jointly delay thermal decomposition. In summary, the prepared modified silicon carbide significantly improves the tensile strength, wear resistance, and temperature resistance of the sealing ring through silicon carbide hardness + nanoscale dispersion + cross-linked network high temperature resistance naphthalene ring rigid structure + double bond cross-linking + hydrogen bond endotherm tensile strength nanoparticle reinforcement + interfacial chemical bonding + multi-scale synergy (silicon carbide + glass fibers), meeting the requirements of industrial equipment for high-performance seals.

[0008] Preferably, the preparation method of the modified siloxane coupling agent includes the following steps: S31. According to the molar parts, under a nitrogen atmosphere, add vinylmethyldifluorosilane and tetrahydrofuran to a reaction flask, stir evenly, then add 2-hydroxy-6-naphthoic acid and sodium hydride, stir and react. After the reaction is completed, filter, wash the organic layer with saturated brine, separate by column chromatography, and dry at 70 °C for 12 h to obtain naphthylvinylsiloxane diacid; S32. According to the molar parts, under a nitrogen atmosphere, add naphthylvinyl siloxanedioic acid and tetrahydrofuran into a reaction flask. After stirring evenly, add γ-aminopropyltrimethoxysilane and tetrabutylammonium bromide, react at 65 - 70 °C for 8 - 11 h, concentrate under reduced pressure, purify by column chromatography, and dry at 80 °C for 16 h to obtain a modified siloxane coupling agent.

[0009] By adopting the above technical solution, Step S31: Preparation of naphthylvinyl siloxanedioic acid. Vinylmethyldifluorosilane and 2-hydroxy-6-naphthoic acid undergo a condensation reaction under the catalysis of sodium hydride. Sodium hydride removes the proton of the hydroxyl group of naphthoic acid to generate a naphthoxy anion, which attacks the fluorine atom in the silane to form an Si - O bond and release HF. Product: naphthylvinyl siloxanedioic acid (a siloxane structure containing a naphthalene ring and a vinyl group). Filter to remove unreacted sodium hydride and by-products. Wash with saturated brine to remove residual acid and ionic impurities. Purify by column chromatography to separate the target product and remove unreacted naphthoic acid or silane. Dry at 70 °C for 12 hours to ensure the product is anhydrous. Step S32: Preparation of the modified siloxane coupling agent. The carboxyl group of naphthylvinyl siloxanedioic acid reacts with the amino group of γ-aminopropyltrimethoxysilane (APTMS) to form an amide bond. The methoxysilyl group of APTMS is introduced into the product, endowing the coupling agent with the ability of hydrolysis and condensation. Concentrate under reduced pressure to remove the solvent tetrahydrofuran. Purify by column chromatography: separate the coupling agent from unreacted APTMS or by-products. Dry at 80 °C for 16 hours to ensure the stability of the product. Functions and synergistic mechanisms of the prepared modified siloxane coupling agent: 1) Structural characteristics and core functions. The naphthalene ring is a rigid aromatic structure, which is not easily deformed or decomposed at high temperatures, endowing the coupling agent with excellent heat resistance (able to withstand the working temperature of the sealing ring). The vinyl active group covalently bonds with the unsaturated double bond in the fluorocarbon elastomer, enhancing the interfacial bonding between the filler (silicon carbide) and the rubber matrix. After hydrolysis, the methoxysilyl group generates silanol groups (Si - OH), which condense with the hydroxyl groups on the surface of silicon carbide to form chemical bonds (Si - O - Si), improving the filler dispersion. 2) Synergistic effects. Enhancement of interfacial compatibility: The siloxane chain segment of the coupling agent binds to the surface of silicon carbide, and the vinyl group crosslinks with the fluorocarbon elastomer to form an "inorganic - organic" bridging network. Enhancement of wear resistance: Silicon carbide is dispersed in the rubber matrix at the nanoscale, and the rigid particles act as physical support points, restricting the sliding of molecular chains and reducing frictional loss. Optimization of heat resistance: The heat resistance of the naphthalene ring is transferred to the silicon carbide / rubber interface, delaying the breakage of molecular chains at high temperatures and enhancing the thermal stability of the sealing ring. In summary, through the unique design of the rigid naphthalene ring and active groups, the modified siloxane coupling agent realizes the efficient combination of silicon carbide filler and fluorocarbon elastomer, significantly improving the wear resistance, heat resistance and mechanical strength of the sealing ring. At the same time, through synergistic effects with the hydrogen bond network of modified glass fiber, a multi-level reinforcement structure is formed to meet the sealing requirements under extreme working conditions.

[0010] Preferably, in step S31, the temperature of the reaction is 110-115 °C and the reaction time is 4-5 h.

[0011] Preferably, in step S31, the molar ratio of vinylmethyldifluorosilane, 2-hydroxy-6-naphthoic acid, and sodium hydride is 1:2.1:2.5-2.7.

[0012] Preferably, in step S32, the molar ratio of naphthylvinylsiloxanedioic acid, γ-aminopropyltrimethoxysilane, and tetrabutylammonium bromide is 1:3.3-3.5:0.08-0.12.

[0013] Preferably, the preparation method of the modified glass fiber comprises the following steps: S71: According to the mass parts, dissolve 10 parts of N-(4-aminophenyl)phenylmaleimide and 6 parts of N-acetyl-L-cysteine in a mixed solution composed of 300 parts of tetrahydrofuran and 250 parts of ethanol. After complete dissolution, add 0.23 parts of benzil dimethyl ketal, irradiate with ultraviolet light at room temperature for 2-3 h, wait for the solvent to evaporate at room temperature, and then place it in a 60 °C oven for vacuum drying for 15 h to obtain intermediate A; S72: According to the mass parts, add 10 parts of the intermediate and 2.4 parts of N,N'-carbonyldiimidazole to 200 parts of dichloromethane, and react under an ice bath for 50-60 min; then add 3.5 parts of γ-aminopropyltrimethoxysilane and react at room temperature for 24-26 h to obtain intermediate B; S73: According to the mass parts, ultrasonically disperse 20 parts of glass fibers with a diameter of 0.5-5 μm and a length of 3-6 mm in 300 parts of an ethanol solution with a mass concentration of 75%. After adjusting the pH of the solution to 9.5 with sodium hydroxide, add 5 parts of intermediate B and heat to 40-45 °C under nitrogen protection for reaction for 6-8 h, centrifuge, filter, wash, and vacuum dry in a 60 °C oven for 24 h to obtain the modified glass fiber.

[0014] By adopting the above technical solution, step S71: Synthesize intermediate A (thiol-ene click reaction). Through the thiol-ene click reaction, the sulfhydryl group (-SH) of N-acetyl-L-cysteine is combined with the vinyl group (C=C) of maleimide to form a C-S bond, realizing grafting. In the grafted structure, a strong hydrogen bond is formed between the side-chain amino group (-NH) and the carbonyl group (C=O) of N-acetyl-L-cysteine, constituting a physical crosslinking network to restrict the sliding of molecular chains. Step S72: Synthesize intermediate B (functionalization of silane coupling agent). N,N'-carbonyldiimidazole activates the carboxyl group (-COOH) of intermediate A, enabling it to react with the amino group (-NH2) of γ-aminopropyltrimethoxysilane to generate an amide bond. Finally, intermediate B carries a siloxane group (Si-OCH3), endowing it with the coupling ability with the hydroxyl group (-OH) on the surface of glass fiber. Step S73: Surface modification of glass fiber. Add intermediate B and react with the hydroxyl group on the surface of glass fiber at 40 - 45 °C (hydrolysis and condensation of siloxane), and finally form a modified layer bonded by covalent bonds. The role of modified glass fiber in the sealing ring: 1) Enhance mechanical properties. Physical crosslinking network: The hydrogen bonds between the side chains of N-acetyl-L-cysteine form dynamic physical crosslinking points to restrict the sliding of molecular chains, significantly improving the tensile strength of the material. Rigid structure: The aromatic ring of N-(4-aminophenyl)maleimide provides rigid support to improve the anti-deformation ability. 2) Improve heat resistance. Hydrogen bond energy absorption mechanism: The dissociation of hydrogen bonds at high temperatures requires a large amount of energy, delaying the thermal decomposition of the material. Stability of silane coupling agent: The siloxane bond of γ-aminopropyltrimethoxysilane is heat-resistant, protecting the stability of the interface between glass fiber and matrix at high temperatures. 3) Optimize interface compatibility. Role of silane coupling agent: The siloxane group of intermediate B combines with the hydroxyl group on the surface of glass fiber, and the maleimide / cysteine structure at the other end interacts with the rubber matrix (such as fluorocarbon elastomer) through polar interactions or chemical bonding, improving the dispersibility and interface bonding force. Synergistic effect with modified silicon carbide: 1) Synergistically enhance mechanical properties. Modified glass fiber provides macroscopic reinforcement (fiber reinforcement effect). The nanoparticles of modified silicon carbide fill the rubber matrix to restrict the movement of molecular chains, forming a microscopic reinforcement network. The two jointly construct a "fiber-nanoparticle" multi-scale reinforcement structure, significantly improving the tensile strength and wear resistance. 2) Synergistically improve heat resistance. Rigid skeleton of glass fiber: Maintain shape stability at high temperatures. Heat resistance of silicon carbide: The high thermal conductivity of nano-silicon carbide disperses heat, delaying the thermal aging of the matrix. 3) Synergistically optimize the interface. Both modified materials are bonded to the rubber matrix through silane coupling agents, forming an intertwined interface network to reduce stress concentration and further improve the fatigue resistance. In summary, through chemical grafting and interface coupling technology, the surface of glass fiber is functionalized, endowing it with high tensile strength, heat resistance, and excellent compatibility with the rubber matrix.Its synergistic effect with modified silicon carbide, through multi-scale reinforcement and interface optimization, ultimately endows the sealing ring with comprehensive performance advantages, meeting the demanding working conditions of high tensile strength, wear resistance, and high temperature resistance.

[0015] Preferably, the vulcanizing agent is sulfur.

[0016] Preferably, the antioxidant is antioxidant 1010.

[0017] In a second aspect, the present application provides a method for preparing a high tensile strength, wear-resistant, and high temperature-resistant sealing ring, adopting the following technical solution: As a general technical concept, the present application also provides a method for preparing the above-mentioned high tensile strength, wear-resistant, and high temperature-resistant sealing ring, including the following steps: S101, Mixing: Mix each component in proportion and mix in a mixer at 140 - 150 °C for 20 - 40 minutes to obtain a mixed material; S102, Extrusion molding: Extrude the mixed material through a twin-screw extruder at 160 - 180 °C to form a sealing ring prototype; S103, Vulcanization: Place the prototype in a vulcanizing furnace and vulcanize at 190 - 200 °C and a pressure of 10 - 20 MPa for 15 - 20 minutes to obtain a high tensile strength, wear-resistant, and high temperature-resistant sealing ring.

[0018] In summary, the beneficial technical effects of the present application are as follows: 1. Significantly improved mechanical properties High tensile strength: Modified glass fiber grafts N-acetyl-L-cysteine (NALC) through thiol-ene click chemistry. The strong hydrogen bond physical cross-linking points formed between its side chains limit the sliding of molecular chains, greatly increasing the cross-linking density of molecular chains, thereby enhancing the tensile strength and mechanical properties of the material. Modified silicon carbide is dispersed in the rubber matrix at the nanoscale and forms a chemical bond with the fluorocarbon elastomer through unsaturated double bonds, constructing a tight network structure and further strengthening the overall mechanical properties.

[0019] 2. Optimized wear resistance Nanoscale dispersion reinforcement: Modified silicon carbide is uniformly dispersed through a coupling agent with a rigid naphthalene ring structure. Its high hardness effectively resists friction and wear, and at the same time, the chemical bond with the rubber matrix reduces the risk of interface peeling. The fluorocarbon elastomer itself has the characteristic of a low friction coefficient. Combining with the wear-resistant synergistic effect of the modified filler, it significantly extends the service life of the sealing ring under dynamic working conditions.

[0020] 3. Breakthrough in high temperature resistance Improved thermal stability: The hydrogen bond network in modified glass fiber dissociates when heated, absorbing a large amount of energy and delaying the thermal decomposition process of the material. The rigid naphthalene ring structure of modified silicon carbide is resistant to high temperature deformation, and the thermal stability of the coupling agent enhances the heat resistance of the matrix.

[0021] Fluorocarbon elastomer support: The inherent high-temperature resistance property of the fluorocarbon chain (capable of withstanding temperatures above 200°C) provides the basic temperature resistance guarantee for the sealing ring.

[0022] 4. Optimization of interfacial compatibility and dispersibility Chemical bonding design: Modified glass fiber and silicon carbide form chemical connections with the matrix through coupling agents such as γ-aminopropyltrimethoxysilane, avoiding filler agglomeration and improving interfacial bonding strength.

[0023] Uniform network structure: The filler and the rubber matrix form an interpenetrating dense network, reducing stress concentration points and enhancing the uniformity of the overall material.

[0024] 5. Enhancement of aging resistance and chemical resistance Properties of fluorocarbon elastomer: The carbon-fluorine chain structure endows the material with excellent oil resistance, solvent resistance, and antioxidant ability, making it suitable for harsh chemical environments.

[0025] Synergistic effect of antioxidants: The antioxidants in the formulation further delay oxidative aging and extend the service life of the sealing ring. Specific implementation manners

[0026] The following will describe the implementation solutions of the present application in detail in combination with embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase. The fluorocarbon elastomer is poly(vinylidene fluoride-co-hexafluoropropylene) purchased from Dalili Chemical Co., Ltd., Hubei Province.

[0027] In the following examples and preparation examples, 1 part by mass represents 50 g, and 1 part by mole represents 0.1 mol.

[0028] Preparation Example 1 Preparation of modified silicon carbide The preparation method of modified silicon carbide is as follows. According to parts by mass, in a nitrogen atmosphere, 20 parts of silicon carbide with a particle size of 50 - 80 nm and 200 parts of deionized water are added to the reactor. After stirring at a stirring speed of 800 rpm for 1 h and standing for 24 h, 2 parts of dodecyltrimethylammonium bromide and 0.5 part of modified siloxane coupling agent are added, and the reaction is carried out at 90°C for 7 h. After washing with deionized water until no precipitate is detected by silver nitrate, filtration and drying are carried out to obtain modified silicon carbide.

[0029] The preparation method of the modified siloxane coupling agent includes the following steps: S31. According to molar parts, under a nitrogen atmosphere, add 1 part of vinylmethyldifluorosilane and 7 L of tetrahydrofuran to a reaction flask. After stirring evenly, add 2.1 parts of 2-hydroxy-6-naphthoic acid and 2.5 parts of sodium hydride, and stir for reaction. The temperature of the reaction is 110 °C, and the reaction time is 5 h. After the reaction ends, filter, wash the organic layer with saturated brine, and perform column chromatography separation (silica gel, 18% n-heptane in ethyl acetate). After drying at 70 °C for 12 h, naphthylvinylsiloxanedioic acid is obtained; S32. According to molar parts, under a nitrogen atmosphere, add 1 part of naphthylvinylsiloxanedioic acid and 10 L of tetrahydrofuran to a reaction flask. After stirring evenly, add 3.3 parts of γ-aminopropyltrimethoxysilane and 0.08 part of tetrabutylammonium bromide, and react at 65 °C for 11 h. Concentrate under reduced pressure and purify by column chromatography (silica gel, 12% methanol in dichloromethane). After drying at 80 °C for 16 h, a modified siloxane coupling agent is obtained.

[0030] Preparation Example 2 Preparation of Modified Silicon Carbide The preparation method of modified silicon carbide is as follows. According to mass parts, under a nitrogen atmosphere, add 20 parts of silicon carbide with a particle size of 50 - 80 nm and 200 parts of deionized water to a reactor, stir at a stirring speed of 800 rpm for 2 h, let stand for 24 h, then add 2.2 parts of dodecyltrimethylammonium bromide and 0.7 part of the modified siloxane coupling agent, and react at 95 °C for 6 h. Wash with deionized water until no precipitate is detected by silver nitrate, filter and dry to obtain modified silicon carbide.

[0031] The preparation method of the modified siloxane coupling agent includes the following steps: S31. According to molar parts, under a nitrogen atmosphere, add 1 part of vinylmethyldifluorosilane and 7 L of tetrahydrofuran to a reaction flask. After stirring evenly, add 2.1 parts of 2-hydroxy-6-naphthoic acid and 2.7 parts of sodium hydride, and stir for reaction. The temperature of the reaction is 115 °C, and the reaction time is 4 h. After the reaction ends, filter, wash the organic layer with saturated brine, and perform column chromatography separation (silica gel, 18% n-heptane in ethyl acetate). After drying at 70 °C for 12 h, naphthylvinylsiloxanedioic acid is obtained; S32. According to molar parts, under a nitrogen atmosphere, add 1 part of naphthylvinylsiloxanedioic acid and 10 L of tetrahydrofuran to a reaction flask. After stirring evenly, add 3.5 parts of γ-aminopropyltrimethoxysilane and 0.12 part of tetrabutylammonium bromide, and react at 70 °C for 8 h. Concentrate under reduced pressure and purify by column chromatography (silica gel, 12% methanol in dichloromethane). After drying at 80 °C for 16 h, a modified siloxane coupling agent is obtained.

[0032] Preparation Example 3 Preparation of Modified Silicon Carbide The preparation method of modified silicon carbide is as follows. By mass fraction, in a nitrogen atmosphere, 20 parts of silicon carbide with a particle size of 50 - 80 nm and 200 parts of deionized water are added to a reactor. Stir for 1.2 h at a stirring speed of 800 rpm, let stand for 24 h, then add 2.1 parts of dodecyltrimethylammonium bromide and 0.6 part of modified siloxane coupling agent, react at 93 °C for 6.7 h, wash with deionized water until no precipitate is detected by silver nitrate, filter and dry to obtain modified silicon carbide.

[0033] The preparation method of the modified siloxane coupling agent includes the following steps: S31: By mole fraction, in a nitrogen atmosphere, add 1 part of vinylmethyldifluorosilane and 7 L of tetrahydrofuran to a reaction flask. After stirring evenly, add 2.1 parts of 2-hydroxy-6-naphthoic acid and 2.6 parts of sodium hydride, and stir to react. The temperature of the reaction is 113 °C, and the reaction time is 4.5 h. After the reaction ends, filter, wash the organic layer with saturated brine, separate by column chromatography (silica gel, 18% n-heptane in ethyl acetate), and dry at 70 °C for 12 h to obtain naphthylvinylsiloxanedioic acid; S32: By mole fraction, in a nitrogen atmosphere, add 1 part of naphthylvinylsiloxanedioic acid and 10 L of tetrahydrofuran to a reaction flask. After stirring evenly, add 3.4 parts of γ-aminopropyltrimethoxysilane and 0.10 part of tetrabutylammonium bromide, react at 68 °C for 9 h, concentrate under reduced pressure, purify by column chromatography (silica gel, 12% methanol in dichloromethane), and dry at 80 °C for 16 h to obtain the modified siloxane coupling agent.

[0034] Preparation Example 4 Preparation of Modified Glass Fiber The preparation method of modified glass fiber includes the following steps: S71: By mass fraction, dissolve 10 parts of N-(4-aminophenyl) maleimide and 6 parts of N-acetyl-L-cysteine in a mixed solution composed of 300 parts of tetrahydrofuran and 250 parts of ethanol. After complete dissolution, add 0.23 part of benzil dimethyl ether, irradiate with ultraviolet light at room temperature for 2.3 h, wait for the solvent to evaporate at room temperature, and then place in a 60 °C oven for vacuum drying for 15 h to obtain Intermediate A; S72: By mass fraction, add 10 parts of the intermediate and 2.4 parts of N,N'-carbonyldiimidazole to 200 parts of dichloromethane, react in an ice bath for 55 min; then add 3.5 parts of γ-aminopropyltrimethoxysilane and react at room temperature for 25 h to obtain Intermediate B; S73. By mass parts, 20 parts of glass fibers with a diameter of 0.5 - 5 μm and a length of 3 - 6 mm are ultrasonically dispersed in 300 parts of an ethanol solution with a mass concentration of 75%. After adjusting the pH of the solution to 9.5 with sodium hydroxide, 5 parts of intermediate B are added and heated to 43°C under nitrogen protection for 7 h. Then, it is centrifuged, filtered, washed, and vacuum dried in an oven at 60°C for 24 h to obtain modified glass fibers.

[0035] Example 1 A high tensile strength, wear-resistant, and high-temperature resistant sealing ring, by mass parts, comprises the following preparation raw materials: 60 parts of fluorocarbon elastomer, 10 parts of methyl vinyl silicone rubber, 25 parts of modified silicon carbide, 8 parts of modified glass fibers, 1 part of zinc oxide, 2 parts of zinc stearate, 1 part of antioxidant 1010, and 2 parts of sulfur; the modified silicon carbide is prepared from Preparation Example 1. The preparation method of the above high tensile strength, wear-resistant, and high-temperature resistant sealing ring comprises the following steps: S101. Mixing: Mix each component in proportion and mix in a mixer at 140°C for 40 minutes to obtain a mixture. S102. Extrusion molding: Extrude the mixture through a twin-screw extruder at 160°C to form a sealing ring prototype. S103. Vulcanization: Place the prototype in a vulcanizing furnace and vulcanize at 190°C and 20 MPa pressure for 20 minutes to obtain a high tensile strength, wear-resistant, and high-temperature resistant sealing ring.

[0036] Example 2 A high tensile strength, wear-resistant, and high-temperature resistant sealing ring, by mass parts, comprises the following preparation raw materials: 65 parts of fluorocarbon elastomer, 13 parts of methyl vinyl silicone rubber, 30 parts of modified silicon carbide, 11 parts of modified glass fibers, 2 parts of zinc oxide, 3 parts of zinc stearate, 1.5 parts of antioxidant 1010, and 4 parts of sulfur; the modified silicon carbide is prepared from Preparation Example 2. The preparation method of the above high tensile strength, wear-resistant, and high-temperature resistant sealing ring comprises the following steps: S101. Mixing: Mix each component in proportion and mix in a mixer at 150°C for 20 minutes to obtain a mixture. S102. Extrusion molding: Extrude the mixture through a twin-screw extruder at 180°C to form a sealing ring prototype. S103. Vulcanization: Place the prototype in a vulcanizing furnace and vulcanize at 200°C and 10 MPa pressure for 15 minutes to obtain a high tensile strength, wear-resistant, and high-temperature resistant sealing ring.

[0037] Example 3 A high-tensile, wear-resistant and high-temperature-resistant sealing ring, calculated by mass parts, comprises the following preparation raw materials: 63 parts of fluorocarbon elastomer, 11 parts of methyl vinyl silicone rubber, 27 parts of modified silicon carbide, 9 parts of modified glass fiber, 1.5 parts of zinc oxide, 2.5 parts of zinc stearate, 1.2 parts of antioxidant 1010, and 3 parts of sulfur; the modified silicon carbide is prepared by Preparation Example 3; The preparation method of the above high-tensile, wear-resistant and high-temperature-resistant sealing ring comprises the following steps: S101, mixing: Mix each component in proportion, and mix in a mixer at 145 °C for 30 minutes to obtain a mixture; S102, extrusion molding: Extrude the mixture through a twin-screw extruder at 170 °C to form a sealing ring prototype; S103, vulcanization: Place the prototype in a vulcanizing furnace, and vulcanize at 195 °C and 15 MPa for 18 minutes to obtain a high-tensile, wear-resistant and high-temperature-resistant sealing ring.

[0038] Comparative Example 1 Same as Example 3, except that unmodified silicon carbide in equal mass parts is used instead of the modified silicon carbide prepared by Preparation Example 3.

[0039] Comparative Example 2 Same as Example 3, except that unmodified glass fiber in equal mass parts is used instead of the modified glass fiber.

[0040] Performance test Take samples of the high-tensile, wear-resistant and high-temperature-resistant sealing rings prepared in Examples 1 - 3 and Comparative Examples 1 - 2, take 3 parallel samples in each group for testing, and take the average value of the results. The test results are shown in Table 1.

[0041] Tensile property test: According to the standard of GB / T 528-1998, use an electronic tensile machine for testing, and the tensile rate is 500 mm / min; Heat resistance test: Place the prepared high-tensile, wear-resistant and high-temperature-resistant sealing ring in a heat aging box, place it at 250 °C for 72 h, and then test its tensile strength respectively according to the above method to judge its heat resistance; Wear resistance test: Refer to GB 9867-2008 for testing, use a DIN abrasion testing machine for testing, under the test conditions of a friction distance of 40 m and a load of 10 N for the prepared high-tensile, wear-resistant and high-temperature-resistant sealing ring, make the sample moving horizontally and the gauze on the drum rub against each other, and use the abrasion volume to represent the wear resistance of the sample.

[0042] Table 1 Performance test Analyzing the data in Table 1, it can be seen that: 1) The high tensile strength, wear-resistant and high-temperature resistant sealing rings prepared in Examples 1 - 3 have excellent tensile strength, wear resistance and temperature resistance, effectively ensuring their quality and performance.

[0043] 2) Through the comparative analysis of the performance of the high tensile strength, wear-resistant and high-temperature resistant sealing rings prepared by combining Example 3 and Comparative Example 1, it is shown that the prepared modified silicon carbide uses vinylmethyl difluorosilane, 2-hydroxy-6-naphthoic acid, γ-aminopropyltrimethoxysilane, etc. as raw materials to synthesize a modified siloxane coupling agent, and then modifies silicon carbide to obtain modified silicon carbide. The modified silicon carbide has the following functions: 1) Improved interfacial compatibility. The unsaturated double bonds in the coupling agent undergo covalent cross-linking with the double bonds of the fluorocarbon elastomer, reducing interfacial defects. After modification, silicon carbide is dispersed in the rubber matrix at the nanoscale, forming a dense network structure that restricts the slippage of molecular chains. 2) Enhanced performance. Wear resistance: The high hardness of silicon carbide and the nanodispersed structure work together to resist friction and wear. High-temperature resistance: The aromatic ring structure of the coupling agent improves thermal stability. Cross-linked network: Restricts the thermal movement of molecular chains and delays the softening of the material at high temperatures. Mechanical properties: The tensile strength is improved through physical cross-linking points (hydrogen bonds, chemical bonds). Synergy with fluorocarbon elastomers: The fluorocarbon chain provides chemical corrosion resistance, and silicon carbide enhances rigidity, forming a "rigid-flexible combination" structure. Double bond cross-linking forms a through-network, simultaneously improving wear resistance and tensile strength. Synergy with modified glass fibers, mechanical complementarity: Glass fibers provide a long aspect ratio enhancement effect, and silicon carbide fills microscopic voids, forming a multi-scale reinforcement system. Heat resistance synergy: The hydrogen bond endothermic of glass fibers and the rigid structure of silicon carbide jointly delay thermal decomposition. In summary, the prepared modified silicon carbide significantly improves the tensile strength, wear resistance and temperature resistance of the sealing ring through silicon carbide hardness + nanodispersion + cross-linked network high-temperature resistance naphthalene ring rigid structure + double bond cross-linking + hydrogen bond endothermic tensile strength nanoparticle reinforcement + interfacial chemical bonding + multi-scale synergy (silicon carbide + glass fiber), meeting the requirements of industrial equipment for high-performance seals.

[0044] 3) Through the comparative analysis of the performance of the high tensile strength, wear-resistant and high-temperature resistant sealing rings prepared by combining Example 3 and Comparative Example 2, it is shown that the modified glass fiber prepared in this application realizes the surface functionalization of glass fiber through chemical grafting and interfacial coupling technology, endowing it with high tensile strength, heat resistance and excellent compatibility with the rubber matrix. Its synergistic effect with modified silicon carbide, through multi-scale reinforcement and interface optimization, finally enables the sealing ring to have comprehensive performance advantages and meet the demanding working conditions requirements of high tensile strength, wear resistance and high temperature resistance.

[0045] The above embodiments are only used to explain the technical solutions of the present application rather than limit them. Although the above embodiments have specifically described the present application, those skilled in the art should understand that the specific implementation manners of the present invention can still be modified or equivalently replaced. Any modification and equivalent replacement that do not depart from the spirit and scope of the present application shall be covered by the protection scope of the present application.

Claims

1. A high-tensile, wear-resistant and high-temperature resistant sealing ring, characterized in that, By mass parts, it includes the following preparation raw materials: 60-65 parts of fluorocarbon elastomer, 10-13 parts of methyl vinyl silicone rubber, 25-30 parts of modified silicon carbide, 8-11 parts of modified glass fiber, 1-2 parts of zinc oxide, 2-3 parts of zinc stearate, 1-1.5 parts of antioxidant, and 2-4 parts of vulcanizing agent.

2. The high-tensile, wear-resistant and high-temperature resistant sealing ring according to claim 1, wherein The preparation method of the modified silicon carbide is as follows: By mass parts, in a nitrogen atmosphere, add 20 parts of silicon carbide with a particle size of 50-80 nm and 200 parts of deionized water to a reactor, stir at a stirring speed of 800 rpm for 1-2 h, let it stand for 24 h, then add 2-2.2 parts of dodecyl trimethyl ammonium bromide and 0.5-0.7 parts of modified siloxane coupling agent, react at 90-95 °C for 6-7 h, wash with deionized water until no precipitate is detected by silver nitrate, filter and dry to obtain the modified silicon carbide.

3. The high-tensile, wear-resistant and high-temperature resistant sealing ring according to claim 2, wherein The preparation method of the modified siloxane coupling agent includes the following steps: S31: By mole parts, in a nitrogen atmosphere, add vinyl methyl difluorosilane and tetrahydrofuran to a reaction flask, stir evenly, then add 2-hydroxy-6-naphthoic acid and sodium hydride, stir and react. After the reaction is completed, filter, wash the organic layer with saturated brine, separate by column chromatography, and dry at 70 °C for 12 h to obtain naphthyl vinyl siloxane diacid; S32: By mole parts, in a nitrogen atmosphere, add naphthyl vinyl siloxane diacid and tetrahydrofuran to a reaction flask, stir evenly, then add γ-aminopropyl trimethoxysilane and tetrabutyl ammonium bromide, react at 65-70 °C for 8-11 h, concentrate under reduced pressure, purify by column chromatography, and dry at 80 °C for 16 h to obtain the modified siloxane coupling agent.

4. The high-tensile, wear-resistant and high-temperature-resistant sealing ring according to claim 3, wherein, In step S31, the temperature of the reaction is 110-115 °C, and the reaction time is 4-5 h.

5. The high-tensile, wear-resistant and high-temperature-resistant sealing ring according to claim 3, characterized in that, In step S31, the molar ratio of vinyl methyl difluorosilane, 2-hydroxy-6-naphthoic acid and sodium hydride is 1:2.1:2.5-2.

7.

6. The high-tensile, wear-resistant and high-temperature resistant sealing ring according to claim 3, characterized in that, In step S32, the molar ratio of naphthyl vinyl siloxane diacid, γ-aminopropyl trimethoxysilane and tetrabutyl ammonium bromide is 1:3.3-3.5:0.08-0.

12.

7. The high-tensile, wear-resistant and high-temperature resistant sealing ring according to claim 1, wherein The preparation method of the modified glass fiber includes the following steps: S71: By mass parts, dissolve 10 parts of N-(4-aminophenyl)phenylmaleimide and 6 parts of N-acetyl-L-cysteine in a mixed solution composed of 300 parts of tetrahydrofuran and 250 parts of ethanol. After dissolution, add 0.23 parts of benzil dimethyl ether, irradiate with ultraviolet light at room temperature for 2-3 h, wait for the solvent to volatilize at room temperature, and then place it in a 60 °C oven for vacuum drying for 15 h to obtain intermediate A; S72: By mass parts, add 10 parts of the intermediate and 2.4 parts of N,N'-carbonyldiimidazole to 200 parts of dichloromethane, react in an ice bath for 50-60 min; then add 3.5 parts of γ-aminopropyl trimethoxysilane and react at room temperature for 24-26 h to obtain intermediate B; S73. By mass fraction, 20 parts of glass fibers with a diameter of 0.5 - 5 μm and a length of 3 - 6 mm are ultrasonically dispersed in 300 parts of an ethanol solution with a mass concentration of 75%. After adjusting the pH of the solution to 9.5 with sodium hydroxide, 5 parts of intermediate B are added and heated to 40 - 45 °C under nitrogen protection for reaction for 6 - 8 h. Then, it is centrifuged, filtered, washed, and vacuum dried in an oven at 60 °C for 24 h to obtain modified glass fibers.

8. The high-tensile, wear-resistant and high-temperature-resistant sealing ring according to claim 1, wherein The vulcanizing agent is sulfur.

9. The high-tensile, wear-resistant and high-temperature-resistant sealing ring according to claim 1, wherein The antioxidant is antioxidant 1010.

10. A preparation method of a high tensile strength, wear-resistant and high-temperature resistant sealing ring according to any one of claims 1-9, characterized in that, It includes the following steps: S101. Kneading: Mix each component in proportion and knead in a mixer at 140 - 150 °C for 20 - 40 minutes to obtain a mixture. S102. Extrusion molding: Extrude the mixture through a twin - screw extruder at 160 - 180 °C to form a seal ring prototype. S103. Vulcanization: Place the prototype in a vulcanizing furnace and vulcanize at 190 - 200 °C and a pressure of 10 - 20 MPa for 15 - 20 minutes to obtain a high - tensile, wear - resistant, and high - temperature - resistant seal ring.

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