Silicone rubber composite material for sealing ring and preparation method thereof

Abstract

The invention belongs to the field of high polymer materials, and discloses a silicone rubber composite material for a sealing ring and a preparation method of the silicone rubber composite material. The high-performance silicone rubber is prepared from the following components in parts by weight: 80-120 parts of methyl vinyl silicone rubber, 20-35 parts of fumed silica, 3-8 parts of hydroxyapatite nanowires, 2-6 parts of polytetrafluoroethylene micro powder, 1-4 parts of a silane coupling agent, 0.5-2.5 parts of a peroxide cross-linking agent, 2-6 parts of modified nano silicon dioxide, 3-8 parts of composite micro powder A and 4-9 parts of composite micro powder B, according to the silicone rubber composite material for the sealing ring and the preparation method of the silicone rubber composite material, the defects that an existing silicone rubber sealing ring material is insufficient in mechanical strength, poor in wear resistance and rapid in performance attenuation after thermal aging are overcome; meanwhile, the problems of poor filler dispersity, weak component synergistic effect and uncontrollable preparation process in an existing modification scheme are solved, and the comprehensive performance of the composite material is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a silicone rubber composite material for sealing rings and its preparation method. Background Technology

[0002] As a core component of a sealing system, the performance of the sealing ring directly determines the sealing effect and the service life of the equipment. Silicone rubber, due to its excellent resistance to high and low temperatures, weather resistance, and elasticity, has become a commonly used base material for sealing rings. However, traditional silicone rubber sealing rings have significant drawbacks: low mechanical strength, making them prone to permanent deformation under pressure; poor wear resistance, leading to easy damage to the sealing surface after long-term friction; and rapid performance degradation after thermal aging, resulting in a significantly shortened service life under high-temperature conditions (such as around engines).

[0003] To address these issues, existing technologies often employ single-filler modification, such as adding nano-silica to enhance mechanical strength. However, unmodified nano-silica tends to agglomerate, resulting in poor interfacial bonding with the silicone rubber matrix and limited modification effectiveness. Alternatively, inorganic fillers like mica and talc can be used for reinforcement, but single inorganic fillers struggle to simultaneously achieve both elasticity and heat resistance. Some solutions attempt composite fillers, but issues arise such as unreasonable component combinations (e.g., failure to consider the synergistic effect of organic-inorganic fillers) and mismatched preparation process parameters (e.g., chaotic filler addition order leading to uneven dispersion), making it impossible to simultaneously improve mechanical properties, heat aging resistance, and wear resistance.

[0004] In addition, existing technologies lack targeted formulation designs for the application scenarios of sealing rings. Most modification solutions only focus on a single performance indicator and fail to form a synergistic system, resulting in the final product being unable to meet the long-term use requirements under complex working conditions.

[0005] Therefore, proposing a silicone rubber composite material with reasonable component matching, controllable preparation process, and excellent comprehensive performance is of great significance for improving the quality of sealing ring products and expanding application scenarios. Summary of the Invention

[0006] The present invention aims to provide a silicone rubber composite material for sealing rings and its preparation method. The present invention aims to overcome the defects of existing silicone rubber sealing ring materials, such as insufficient mechanical strength, poor wear resistance, and rapid performance degradation after thermal aging. At the same time, it solves the problems of poor filler dispersion, weak component synergy, and uncontrollable preparation process in existing modification schemes, so as to achieve a significant improvement in the comprehensive performance of composite materials.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The technical solution provided by this invention is: This invention provides a silicone rubber composite material for sealing rings, which is composed of the following components in parts by weight: 80-120 parts of methyl vinyl silicone rubber, 20-35 parts of fumed silica, 3-8 parts of hydroxyapatite nanowires, 2-6 parts of polytetrafluoroethylene micro powder, 1-4 parts of silane coupling agent, 0.5-2.5 parts of peroxide crosslinking agent, 2-6 parts of modified nano silica, 3-8 parts of composite micro powder A, and 4-9 parts of composite micro powder B.

[0008] Furthermore, the modified nano-silica is KH-570 modified nano-silica with a particle size of 20-40 nm and a KH-570 grafting modification rate of ≥80%. It has also undergone ultrasonic dispersion pretreatment (ultrasonic power 150-250W, time 20-40min). The introduction of KH-570 can improve the interfacial compatibility between nano-silica and silicone rubber matrix, avoid agglomeration, and its double bond structure can participate in cross-linking reaction, thereby improving the mechanical strength and structural stability of the composite material.

[0009] Furthermore, composite micropowder A is an epoxy resin-mica composite micropowder, wherein the epoxy resin is a bisphenol A type epoxy resin, the mass ratio of epoxy resin to curing agent diaminodiphenylmethane is 100:25-35, the mass ratio of epoxy resin to mica is 2:1-4:1, and the particle size is 1-5μm. After the epoxy resin is cured by the curing agent, it is combined with mica. Bisphenol A type epoxy resin has excellent adhesion and heat resistance, while mica has a layered structure and high rigidity. The combination of the two can improve the mechanical strength of the composite material while enhancing its heat resistance and dimensional stability, and prevent the sealing ring from deforming at high temperatures.

[0010] Furthermore, composite micro powder B is a composite powder of butyl acrylate-styrene copolymer-talc powder, wherein the mass ratio of butyl acrylate to styrene is 1.8:1-2.2:1, the mass proportion of talc powder is 10%-20%, and the particle size is 0.8-4μm. The butyl acrylate-styrene copolymer has good elasticity and impact resistance, while talc powder has a low coefficient of friction and high dispersibility. The combination of the two can improve the elastic recovery and wear resistance of the composite material and extend the friction service life of the sealing ring.

[0011] Furthermore, the hydroxyapatite nanowires have a diameter of 50-100 nm and an aspect ratio of 20-50. Their nanowire structure can form a skeleton support, further enhancing the tensile strength and tear strength of the composite material. The polytetrafluoroethylene micropowder has a particle size of 0.5-2 μm and is low molecular weight polytetrafluoroethylene, which can reduce the friction coefficient of the composite material and improve its wear resistance.

[0012] Furthermore, the vinyl content in methyl vinyl silicone rubber is 0.15-0.25% by mass, and the vinyl content determines the crosslinking density. This range can balance elasticity and mechanical strength. The silane coupling agent is γ-glycidoxypropyltrimethoxysilane, which can further improve the interfacial bonding between inorganic fillers and organic matrix. The peroxide crosslinking agent is 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, which has high crosslinking efficiency and can form a stable crosslinking network.

[0013] The present invention also provides a method for preparing the above-mentioned silicone rubber composite material, comprising the following steps: Preparation of composite micro powder A: Bisphenol A type epoxy resin and diaminodiphenylmethane are mixed at a mass ratio of 100:25-35 and stirred at a temperature of 120-140℃ and a rotation speed of 80-100 r / min for 2-3 hours. After cooling, the mixture is pulverized to a particle size of 1-5 μm and then mixed with mica at a mass ratio of 2:1-4:1. The mixture is stirred and compounded at a temperature of 80-100℃ and a rotation speed of 100-150 r / min for 30-60 minutes. After cooling, composite micro powder A is obtained. S1: Preparation of modified nano-silica: Nano-silica is dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 3-6 mg / mL. 0.5-1.2 times the mass of KH-570 is added, and the mixture is stirred for 3-5 h at a temperature of 50-70℃ and a rotation speed of 100-150 r / min. After filtration, the mixture is washed 2-3 times with ethanol and dried for 4-6 h at a vacuum of 0.08-0.1 MPa and a temperature of 60-80℃ to obtain modified nano-silica. This step achieves graft modification by reacting the siloxane groups of KH-570 with the hydroxyl groups on the surface of nano-silica. At the same time, anhydrous ethanol and ultrasonic pretreatment ensure uniform dispersion.

[0014] S2: Plasticizing: Put methyl vinyl silicone rubber into an internal mixer and plasticize it for 6-8 minutes at a temperature of 85-95℃ and a speed of 35-45r / min. The purpose of plasticizing is to soften the silicone rubber matrix and facilitate the subsequent dispersion of fillers.

[0015] S3: First stage mixing: Add fumed silica and silane coupling agent to the material obtained in step 2, and mix for 18-22 minutes at a temperature of 105-115℃ and a rotation speed of 28-38r / min to obtain the first mixture; fumed silica is a reinforcing filler, and the addition of silane coupling agent at this stage can improve its compatibility with silicone rubber in advance.

[0016] S4: Second stage mixing: Add the modified nano-silica and composite micro powder A prepared in S1 to the first mixture, and mix for 8-12 minutes at a temperature of 95-105℃ and a rotation speed of 25-30r / min to obtain the second mixture; this temperature and rotation speed can ensure that the modified nano-silica (high temperature agglomeration should be avoided) and the composite micro powder A (uniform dispersion is required to form a supporting structure) are fully dispersed.

[0017] S5: Third stage mixing: Add hydroxyapatite nanowires, composite micro powder B and polytetrafluoroethylene micro powder to the second mixture, and mix for 12-18 minutes at a temperature of 90-100℃ and a rotation speed of 22-32 r / min to obtain the third mixture; hydroxyapatite nanowires need to be mixed at low speed to avoid breakage, and composite micro powder B and polytetrafluoroethylene micro powder need to be fully combined with the matrix to exert wear resistance. Add them at intervals of 2-4 minutes, and stir for 1.5-2.5 minutes after each material is added to further ensure uniform dispersion.

[0018] S6: Crosslinking agent mixing: Add peroxide crosslinking agent to the third mixture and mix for 8-12 minutes at a temperature of 75-85℃ and a rotation speed of 18-28r / min to obtain the rubber compound; low-temperature mixing can avoid premature decomposition of peroxide and ensure crosslinking efficiency.

[0019] S7: Vulcanization molding: Place the rubber compound into the mold (preheating temperature 160-170℃, preheating time 5-8min), vulcanize at 165-175℃ and 6-9MPa for 12-18min, and then vulcanize again at 190-200℃ for 2.5-3.5h to obtain the silicone rubber composite material; the first vulcanization achieves preliminary molding, and the second vulcanization can further improve the crosslinking network and enhance performance stability.

[0020] The beneficial effects of this technical solution are: (1) This technical solution achieves significant advantages in mechanical properties through the synergistic combination of specific components. The modified nano silica is grafted with KH-570, and the double bonds in its molecular structure can undergo cross-linking reaction with the silicone rubber matrix. At the same time, the surface modification layer can improve the interfacial compatibility with the matrix, avoid the agglomeration of nanoparticles, and ensure that the filler is uniformly dispersed in the matrix. Hydroxyapatite nanowires, with their unique nanowire structure, build a three-dimensional skeleton support in the composite material, complementing the modified nano silica and jointly enhancing the overall structural strength of the material. In addition, the silane coupling agent can further optimize the interfacial bonding state between the inorganic filler and the organic matrix, reduce interfacial defects between components, and make the material less prone to stress concentration damage when subjected to external forces, thereby improving the overall mechanical properties.

[0021] (2) In terms of heat resistance, the bisphenol A type epoxy resin in composite micro powder A has excellent high temperature stability, and the aromatic ring in its molecular structure can increase the thermal decomposition temperature; mica has a layered structure, which can form a physical barrier inside the material, hindering the transfer and diffusion of heat, and delaying the thermal aging and degradation of molecular chains at high temperature. After the two are combined, they not only retain their respective heat resistance characteristics, but also further enhance the upper limit of the material's heat resistance through synergistic effect. This, combined with the high and low temperature resistance of the silicone rubber matrix itself, enables the composite material to maintain structural stability under high temperature conditions and is not prone to softening, deformation and other problems.

[0022] (2) The improvement in wear resistance depends on the synergistic effect of composite micro powder B and polytetrafluoroethylene micro powder. The butyl acrylate-styrene copolymer in composite micro powder B has good elastic recovery, which can buffer the impact of external force during friction and reduce surface damage. Talc powder, as an inorganic filler, has a low coefficient of friction, which can reduce the frictional resistance between the material surface and the contact parts. At the same time, low molecular weight polytetrafluoroethylene micro powder has excellent lubrication performance, which can form a lubricating layer on the material surface and further reduce friction loss. The three components work together to maintain the elasticity of silicone rubber to ensure the sealing effect, and significantly improve the wear resistance of the material, extending the service life of the sealing ring under long-term friction conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a silicone rubber composite material for sealing rings and its preparation method proposed in this invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The specific implementation process is as follows: Example 1: Please see Figure 1 The present invention provides a technical solution: a silicone rubber composite material for sealing rings and a method for preparing the same, comprising the following components: 80 parts of methyl vinyl silicone rubber (vinyl mass fraction 0.15%), 20 parts of fumed silica (specific surface area 150 m² / g). 2 / g), 3 parts of hydroxyapatite nanowires (50nm diameter, aspect ratio 20), 2 parts of polytetrafluoroethylene micro powder (0.5μm particle size, low molecular weight), 1 part of silane coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane), 0.5 parts of peroxide crosslinking agent (2,5-dimethyl-2,5-di-tert-butylperoxyhexane), 2 parts of modified nano-silica (KH-570 modified, 20nm particle size, 80% grafting modification rate, ultrasonic pretreatment power 150W, time 20min), 3 parts of composite micro powder A (epoxy resin-mica composite micro powder, bisphenol A type epoxy resin to curing agent diaminodiphenylmethane mass ratio 100:25, epoxy resin to mica mass ratio 2:1, particle size 1μm), composite micro powder B 4 parts (butyl acrylate-styrene copolymer-talc composite powder, butyl acrylate to styrene mass ratio 1.8:1, talc mass percentage 10%, particle size 0.8μm).

[0026] The preparation steps are as follows: Preparation of composite micro powder A: Bisphenol A type epoxy resin and diaminodiphenylmethane were mixed at a mass ratio of 100:25 and stirred at 120℃ and 80 r / min for 2 h. After cooling, the mixture was pulverized to a particle size of 1 μm and then mixed with mica at a mass ratio of 2:1. The mixture was stirred and compounded at 80℃ and 100 r / min for 30 min. After cooling, composite micro powder A was obtained. S1: Preparation of modified nano-silica: Nano-silica was dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 3 mg / mL. KH-570 with a mass of 0.5 times that of nano-silica was added. The mixture was stirred at 50℃ and 100 r / min for 3 h. After the reaction was completed, the mixture was filtered, washed twice with ethanol, and dried at 0.08 MPa and 60℃ for 4 h to obtain modified nano-silica. S2: Plasticizing: Put methyl vinyl silicone rubber into an internal mixer and plasticize it for 6 minutes at a temperature of 85℃ and a speed of 35r / min. S3: First stage mixing: Add fumed silica and silane coupling agent to the material obtained in S2, and mix for 18 minutes at a temperature of 105℃ and a rotation speed of 28r / min to obtain the first mixture; S4: Second stage mixing: Add the modified nano-silica and composite micro powder A prepared in S1 to the first mixture, and mix for 8 minutes at a temperature of 95℃ and a rotation speed of 25r / min to obtain the second mixture; S5: Third stage mixing: Hydroxyapatite nanowires, composite micro powder B, and polytetrafluoroethylene micro powder are added to the second mixture in sequence, with an interval of 2 minutes between the addition of adjacent materials. After each material is added, the mixture is stirred for 1.5 minutes before adding the next material. The mixture is then mixed for 12 minutes at a temperature of 90℃ and a rotation speed of 22r / min to obtain the third mixture. S6: Crosslinking agent mixing: Add peroxide crosslinking agent to the third mixture and mix for 8 minutes at a temperature of 75℃ and a rotation speed of 18r / min to obtain the rubber compound; S7: Vulcanization molding: Place the rubber compound into a preheated mold (preheating temperature 160℃, preheating time 5min), vulcanize at 165℃ and 6MPa for 12min, and then vulcanize again at 190℃ for 2.5h to obtain the silicone rubber composite material.

[0027] Performance indicators Test Results Tensile strength 8.5MPa Tear strength 25kN / m Shore A hardness 60 Tensile strength retention rate at 200℃ for 72 hours 85% Wear amount 45mg This embodiment uses the lower limit of the weight parts of each component, and the experimental data shows that the basic performance of the material meets the standards. The tensile strength is 8.5 MPa and the tear strength is 25 kN / m, which meets the mechanical performance requirements of medium and low load sealing scenarios. This is due to the uniform dispersion of modified nano-silica and the skeletal support of hydroxyapatite nanowires. The Shore A hardness is 60, which balances elasticity and rigidity and can ensure the fit between the sealing ring and the sealing surface. The tensile strength retention rate of 85% after 200℃×72h indicates that the synergistic effect of epoxy resin and mica in composite micro powder A effectively improves the heat resistance stability. The wear loss is 45 mg. The combination of composite micro powder B and polytetrafluoroethylene micro powder reduces friction loss, and the overall performance is suitable for conventional sealing requirements.

[0028] Example 2: Please see Figure 1 The present invention provides a technical solution: a silicone rubber composite material for sealing rings and a method for preparing the same, comprising the following components: 100 parts of methyl vinyl silicone rubber (vinyl mass fraction 0.2%), 28 parts of fumed silica (specific surface area 220 m² / g). 2 / g), 5 parts hydroxyapatite nanowires (70nm diameter, aspect ratio 35), 4 parts polytetrafluoroethylene micro powder (1.2μm particle size, low molecular weight), 2.5 parts silane coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane), 1.5 parts peroxide crosslinking agent (2,5-dimethyl-2,5-di-tert-butylperoxyhexane), 4 parts modified nano silica (KH-570 modified, 30nm particle size, graft modification rate 85%, ultrasonic pretreatment power 200W, time 30min), 5 parts composite micro powder A (epoxy resin-mica composite micro powder, bisphenol A type epoxy resin and curing agent diaminodiphenylmethane mass ratio 100:30, epoxy resin and mica mass ratio 3:1, particle size 3μm), composite micro powder B 7 parts (butyl acrylate-styrene copolymer-talc composite powder, butyl acrylate to styrene mass ratio 2:1, talc mass percentage 15%, particle size 2μm).

[0029] The preparation steps are as follows: Preparation of composite micro powder A: Bisphenol A type epoxy resin and diaminodiphenylmethane were mixed at a mass ratio of 100:30 and stirred at 130℃ and 90 r / min for 2.5 h. After cooling, the mixture was pulverized to a particle size of 3 μm and then mixed with mica at a mass ratio of 3:1. The mixture was stirred and compounded at 90℃ and 120 r / min for 45 min. After cooling, composite micro powder A was obtained. S1: Preparation of modified nano-silica: Nano-silica was dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 4.5 mg / mL. KH-570 with a mass of 0.8 times that of nano-silica was added. The mixture was stirred and reacted for 4 h at a temperature of 60℃ and a speed of 120 r / min. After the reaction was completed, the mixture was filtered, washed 3 times with ethanol, and dried for 5 h at a vacuum of 0.09 MPa and a temperature of 70℃ to obtain modified nano-silica. S2: Plasticizing: Put methyl vinyl silicone rubber into an internal mixer and plasticize it for 7 minutes at a temperature of 90℃ and a speed of 40r / min. S3: First stage mixing: Add fumed silica and silane coupling agent to the material obtained in S2, and mix for 20 minutes at a temperature of 110℃ and a rotation speed of 33r / min to obtain the first mixture; S4: Second stage mixing: Add the modified nano-silica and composite micro powder A prepared in S1 to the first mixture, and mix for 10 min at a temperature of 100℃ and a rotation speed of 28 r / min to obtain the second mixture; S5: Third stage mixing: Hydroxyapatite nanowires, composite micro powder B, and polytetrafluoroethylene micro powder are added to the second mixture in sequence, with an interval of 3 minutes between the addition of adjacent materials. After each material is added, the mixture is stirred for 2 minutes before adding the next material. The mixture is then mixed for 15 minutes at a temperature of 95℃ and a rotation speed of 27r / min to obtain the third mixture. S6: Crosslinking agent mixing: Add peroxide crosslinking agent to the third mixture and mix for 10 min at 80℃ and 23r / min to obtain the rubber compound; S7: Vulcanization molding: Place the rubber compound into a preheated mold (preheating temperature 165℃, preheating time 6min), vulcanize at 170℃ and 7.5MPa for 15min, and then vulcanize again at 195℃ for 3h to obtain the silicone rubber composite material.

[0030] Performance indicators Test Results Tensile strength 10.2MPa Tear strength 32kN / m Shore A hardness 65 Tensile strength retention rate at 200℃ for 72 hours 92% Wear amount 32mg This embodiment represents the preferred solution based on the median weight of each component, and experimental data demonstrate optimal overall performance. The tensile strength is 10.2 MPa and the tear strength is 32 kN / m, significantly improved compared to Example 1. This is due to the increased grafting rate of the modified nanowires to 85%, resulting in a tighter interface with the matrix. The aspect ratio of the hydroxyapatite nanowires is optimized to 35, enhancing the skeletal support. The Shore A hardness is 65, achieving the best balance between elasticity and rigidity, suitable for the bonding and deformation resistance requirements of most sealing scenarios. The tensile strength retention rate at 200℃ for 72 hours is 92%, with the epoxy resin to mica mass ratio in composite micropowder A at 3:1, providing optimal heat barrier performance. The wear loss is 32 mg, with talc powder accounting for 15% in composite micropowder B, synergistically with polytetrafluoroethylene micropowder, achieving peak lubrication and anti-wear performance, meeting the requirements of medium-to-high load, high-temperature sealing scenarios.

[0031] Example 3: Please see Figure 1 The present invention provides a technical solution: a silicone rubber composite material for sealing rings and a method for preparing the same, comprising the following components: 120 parts of methyl vinyl silicone rubber (vinyl mass fraction 0.25%), 35 parts of fumed silica (specific surface area 300 m² / g). 2 / g), 8 parts of hydroxyapatite nanowires (diameter 100nm, aspect ratio 50), 6 parts of polytetrafluoroethylene micro powder (particle size 2μm, low molecular weight), 4 parts of silane coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane), 2.5 parts of peroxide crosslinking agent (2,5-dimethyl-2,5-di-tert-butylperoxyhexane), 6 parts of modified nano silica (KH-570 modified, particle size 40nm, graft modification rate 90%, ultrasonic pretreatment power 250W, time 40min), 8 parts of composite micro powder A (epoxy resin-mica composite micro powder, bisphenol A type epoxy resin and curing agent diaminodiphenylmethane mass ratio 100:35, epoxy resin and mica mass ratio 4:1, particle size 5μm), composite micro powder B 9 parts (butyl acrylate-styrene copolymer-talc composite powder, butyl acrylate to styrene mass ratio 2.2:1, talc mass percentage 20%, particle size 4μm).

[0032] The preparation steps are as follows: Preparation of composite micro powder A: Bisphenol A type epoxy resin and diaminodiphenylmethane were mixed at a mass ratio of 100:35 and stirred at 140℃ and 100 r / min for 3 h. After cooling, the mixture was pulverized to a particle size of 5 μm and then mixed with mica at a mass ratio of 4:1. The mixture was stirred and compounded at 100℃ and 150 r / min for 60 min. After cooling, composite micro powder A was obtained. S1: Preparation of modified nano-silica: Nano-silica was dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 6 mg / mL. KH-570 with a mass of 1.2 times that of nano-silica was added. The mixture was stirred and reacted for 5 h at a temperature of 70℃ and a speed of 150 r / min. After the reaction was completed, the mixture was filtered, washed 3 times with ethanol, and dried for 6 h at a vacuum of 0.1 MPa and a temperature of 80℃ to obtain modified nano-silica. S2: Plasticizing: Put methyl vinyl silicone rubber into an internal mixer and plasticize for 8 minutes at a temperature of 95℃ and a speed of 45r / min. S3: First stage mixing: Add fumed silica and silane coupling agent to the material obtained in S2, and mix for 22 minutes at a temperature of 115℃ and a rotation speed of 38r / min to obtain the first mixture; S4: Second stage mixing: Add the modified nano-silica and composite micro powder A prepared in S1 to the first mixture, and mix for 12 min at a temperature of 105℃ and a rotation speed of 30 r / min to obtain the second mixture; S5: Third stage mixing: Hydroxyapatite nanowires, composite micro powder B, and polytetrafluoroethylene micro powder are added to the second mixture in sequence, with an interval of 4 min between the addition of adjacent materials. After each material is added, the mixture is stirred for 2.5 min before adding the next material. The mixture is then mixed for 18 min at a temperature of 100℃ and a rotation speed of 32 r / min to obtain the third mixture. S6: Crosslinking agent mixing: Add peroxide crosslinking agent to the third mixture and mix for 12 minutes at a temperature of 85℃ and a rotation speed of 28r / min to obtain the rubber compound; S7: Vulcanization molding: Place the rubber compound into a preheated mold (preheating temperature 170℃, preheating time 8min), vulcanize at 175℃ and 9MPa for 18min, and then vulcanize again at 200℃ for 3.5h to obtain the silicone rubber composite material.

[0033] Performance indicators Test Results Tensile strength 11.5MPa Tear strength 36kN / m Shore A hardness 70 Tensile strength retention rate at 200℃ for 72 hours 95% Wear amount 28mg This embodiment uses the upper limit of the weight parts of each component, and the experimental data shows that the mechanical strength and heat resistance are optimal. The tensile strength is 11.5 MPa and the tear strength is 36 kN / m, which are the highest among the four embodiments. This is because the amount of modified nano-silica added is increased to 6 parts with a grafting rate of 90%, and the amount of hydroxyapatite nanowires added is 8 parts with an aspect ratio of 50, forming a more stable internal support structure. The Shore A hardness is 70, which is relatively rigid and suitable for sealing scenarios that require resistance to compression deformation under high loads. The tensile strength retention rate at 200℃×72h is 95%. The amount of composite micro powder A added is 8 parts and the proportion of epoxy resin is increased, which achieves peak heat resistance stability. The abrasion loss is 28 mg. The high addition of composite micro powder B and polytetrafluoroethylene micro powder synergistically results in the best abrasion resistance performance, which can be adapted to high-load, high-temperature and harsh sealing environments.

[0034] Example 4: Please see Figure 1 The present invention provides a technical solution: a silicone rubber composite material for sealing rings and a method for preparing the same, comprising the following components: 90 parts of methyl vinyl silicone rubber (vinyl mass fraction 0.2%), 25 parts of fumed silica (specific surface area 200 m² / g). 2 / g), 6 parts of hydroxyapatite nanowires (diameter 80nm, aspect ratio 40), 3 parts of polytetrafluoroethylene micro powder (particle size 1μm, low molecular weight), 2 parts of silane coupling agent (γ-glycidyl etheroxypropyltrimethoxysilane), 1 part of peroxide crosslinking agent (2,5-dimethyl-2,5-di-tert-butylperoxyhexane), 3 parts of modified nano silica (KH-570 modified, particle size 25nm, graft modification rate 82%, ultrasonic pretreatment power 180W, time 25min), 6 parts of composite micro powder A (epoxy resin-mica composite micro powder, bisphenol A type epoxy resin to curing agent diaminodiphenylmethane mass ratio 100:32, epoxy resin to mica mass ratio 3.5:1, particle size 2μm), composite micro powder B 5 parts (butyl acrylate-styrene copolymer-talc composite powder, butyl acrylate to styrene mass ratio 2.1:1, talc mass percentage 12%, particle size 1.5μm).

[0035] The preparation steps are as follows: Preparation of composite micro powder A: Bisphenol A type epoxy resin and diaminodiphenylmethane were mixed at a mass ratio of 100:32 and stirred at 135℃ and 95 r / min for 2.8 h. After cooling, the mixture was pulverized to a particle size of 2 μm and then mixed with mica at a mass ratio of 3.5:1. The mixture was stirred and compounded at 95℃ and 130 r / min for 40 min. After cooling, composite micro powder A was obtained. S1: Preparation of modified nano-silica: Nano-silica was dispersed in anhydrous ethanol to prepare a dispersion with a concentration of 4 mg / mL. KH-570 with a mass of 0.7 times that of nano-silica was added. The mixture was stirred and reacted at 55℃ and 110 r / min for 3.5 h. After the reaction was completed, the mixture was filtered, washed twice with ethanol, and dried at 0.085 MPa and 65℃ for 4.5 h to obtain modified nano-silica. S2: Plasticizing: Put methyl vinyl silicone rubber into an internal mixer and plasticize for 6.5 min at a temperature of 88℃ and a speed of 38 r / min; S3: First stage mixing: Add fumed silica and silane coupling agent to the material obtained in S2, and mix for 19 minutes at a temperature of 108℃ and a rotation speed of 30r / min to obtain the first mixture; S4: Second stage mixing: Add the modified nano-silica and composite micro powder A prepared in S1 to the first mixture, and mix for 9 min at a temperature of 98℃ and a rotation speed of 27r / min to obtain the second mixture; S5: Third stage mixing: Hydroxyapatite nanowires, composite micro powder B, and polytetrafluoroethylene micro powder are added to the second mixture in sequence, with an interval of 2.5 min between the addition of adjacent materials. After each material is added, the mixture is stirred for 2 min before adding the next material. The mixture is then mixed for 14 min at a temperature of 92℃ and a rotation speed of 25 r / min to obtain the third mixture. S6: Crosslinking agent mixing: Add peroxide crosslinking agent to the third mixture and mix for 9 minutes at a temperature of 78℃ and a rotation speed of 20r / min to obtain the rubber compound; S7: Vulcanization molding: Place the rubber compound into a preheated mold (preheating temperature 162℃, preheating time 7min), vulcanize at 168℃ and 8MPa for 14min, and then vulcanize again at 198℃ for 2.8h to obtain the silicone rubber composite material.

[0036] Performance indicators Test Results Tensile strength 9.8MPa Tear strength 30kN / m Shore A hardness 63 Tensile strength retention rate at 200℃ for 72 hours 89% Wear amount 38mg This embodiment uses the weight proportions of each component and the intermediate values ​​of process parameters. The experimental data demonstrates the balance of performance and process adaptability. The tensile strength is 9.8 MPa and the tear strength is 30 kN / m, meeting the mechanical requirements of most sealing scenarios. The addition of modified nano-silica and hydroxyapatite nanowires is moderate, balancing performance and cost. The Shore A hardness is 63, balancing elasticity and rigidity, and is suitable for the sealing surface adhesion requirements of conventional equipment. The tensile strength retention rate is 89% after 200℃×72h, the composite micro powder A ratio is optimized, and the heat resistance is stable. The wear loss is 38 mg, and the wear resistance meets the standard. Moreover, the preparation process parameters (such as plasticizing at 88℃ and mixing at 25-30 r / min) are conditions that can be easily achieved with conventional industrial equipment, facilitating large-scale production and making it suitable for mass production of general-purpose sealing rings.

[0037] Comparative Example 1: Please see Figure 1 The present invention provides a comparative scheme: except for unmodified nano-silica, the rest is the same as in Example 2.

[0038] Except for the preparation steps of unmodified nano-silica and the second stage of mixing unmodified nano-silica, the preparation steps are the same as in Example 2.

[0039] Performance indicators Test Results Tensile strength 6.2MPa Tear strength 18kN / m Shore A hardness 55 Tensile strength retention rate at 200℃ for 72 hours 82% Wear amount 42mg The comparative example lacked modified nano-silica, and the experimental data were significantly lower than those of Example 2. The tensile strength was 6.2 MPa and the tear strength was 18 kN / m. Due to the lack of interfacial cross-linking and dispersion reinforcement from modified nano-silica, the internal structural integrity of the material was insufficient, resulting in a significant decrease in mechanical properties. The Shore A hardness was 55, indicating insufficient rigidity, making the sealing ring prone to deformation under pressure and affecting the sealing effect. The tensile strength retention rate at 200℃ for 72 h was 82%. Although composite micro-powder A provided some heat resistance, the lack of thermal stabilization assistance from modified nano-silica slightly reduced the heat resistance. The wear loss was 42 mg, indicating a slight decrease in wear resistance due to insufficient mechanical support. This demonstrates that modified nano-silica is a key component for improving the mechanical and structural stability of the material.

[0040] Comparative Example 2: Please see Figure 1 The present invention provides a comparative scheme: except for the absence of composite micro powder A, the rest is the same as in Example 2.

[0041] The preparation steps are the same as in Example 2, except for the second stage of mixing without composite micro powder A.

[0042] Performance indicators Test Results Tensile strength 7.8MPa Tear strength 22kN / m Shore A hardness 58 Tensile strength retention rate at 200℃ for 72 hours 65% Wear amount 35mg The comparative example lacked composite micropowder A, resulting in the most significant decrease in heat resistance performance in the experimental data. The tensile strength retention rate after 200℃×72h was only 65%, due to the absence of the high-temperature resistance of epoxy resin and the thermal barrier effect of mica in composite micropowder A. This led to easy degradation of the molecular chains at high temperatures and a decrease in structural stability. The tensile strength was 7.8MPa, and the tear strength was 22kN / m, indicating reduced mechanical properties due to the lack of rigid support from composite micropowder A. The Shore A hardness was 58, indicating insufficient rigidity, and the sealing ring easily softened and deformed at high temperatures. The abrasion loss was 35mg. Although composite micropowder B and polytetrafluoroethylene micropowder played a role, the overall performance was unsuitable for high-temperature scenarios due to the lack of heat resistance, proving that composite micropowder A is the core component for improving the material's heat resistance stability.

[0043] Comparative Example 3: Please see Figure 1 The present invention provides a comparative scheme: except for the absence of composite micro powder B, it is the same as Example 2.

[0044] The preparation steps are the same as in Example 2, except for the third stage of mixing without composite micro powder B.

[0045] Performance indicators Test Results Tensile strength 9.0MPa Tear strength 28kN / m Shore A hardness 64 Tensile strength retention rate at 200℃ for 72 hours 90% Wear amount 60mg The comparative example lacked composite micro-powder B, resulting in a significant decrease in wear resistance in the experimental data. The wear loss was 60 mg, double that of 32 mg in Example 2. This is because the composite micro-powder B lacks the elastic buffering properties of the butyl acrylate-styrene copolymer and the low-friction characteristics of talc. Polytetrafluoroethylene micro-powder alone cannot meet the wear resistance requirements, and the sealing surface is easily damaged under long-term friction. The tensile strength was 9.0 MPa, and the tear strength was 28 kN / m. The mechanical properties were well maintained due to the effects of modified nano-silica and composite micro-powder A. The Shore A hardness was 64, indicating suitable rigidity. The tensile strength retention rate was 90% after 200℃×72h, showing stable heat resistance. However, the lack of wear resistance makes the material unsuitable for high-friction sealing scenarios, proving that composite micro-powder B is the key component for improving the wear resistance of the material.

[0046] Comparative Example 4: Please see Figure 1 The present invention provides a comparative scheme: the modified nano-silica in Example 2 is replaced with unmodified nano-silica, and the rest is the same as in Example 2.

[0047] The preparation steps are the same as in Example 2, except that there is no modified nano-silica preparation step and unmodified nano-silica is added directly.

[0048] Performance indicators Test Results Tensile strength 6.5MPa Tear strength 19kN / m Shore A hardness 56 Tensile strength retention rate at 200℃ for 72 hours 80% Wear amount 48mg This comparative example replaced modified nano-silica with unmodified nano-silica. The experimental data revealed issues with dispersion and interfacial bonding. The tensile strength was 6.5 MPa, and the tear strength was 19 kN / m. Because the unmodified nano-silica lacked a KH-570 modification layer, it easily agglomerated and had poor interfacial bonding with the matrix, failing to form effective reinforcement. The Shore A hardness was 56, indicating insufficient rigidity. The tensile strength retention rate after 72 hours at 200℃ was 80%, with agglomerated nanoparticles leading to uneven heat conduction and localized aging. The abrasion loss was 48 mg, with uneven dispersion causing significant differences in surface abrasion resistance and localized wear. This demonstrates that KH-570 modification and ultrasonic pretreatment are crucial for the dispersion and material properties of nano-silica, representing a key improvement that distinguishes it from unmodified fillers.

[0049] Comparative Example 5: Please see Figure 1 The present invention provides a comparative scheme: replacing the composite micro powder A in Example 2 with a single epoxy resin, while the rest is the same as in Example 2.

[0050] In the second stage of the preparation process, a single epoxy resin is added during mixing, and the rest is the same as in Example 2.

[0051] Performance indicators Test Results Tensile strength 7.5MPa Tear strength 21kN / m Shore A hardness 57 Tensile strength retention rate at 200℃ for 72 hours 68% Wear amount 36mg In this comparative example, composite micropowder A was replaced with a single epoxy resin. The experimental data showed the lack of synergistic effect of the composite. The tensile strength retention rate at 200℃ for 72h was 68%. Although epoxy resin has a certain heat resistance, it lacks the layered thermal barrier of mica, allowing heat to easily penetrate the material and accelerate aging. The tensile strength was 7.5MPa and the tear strength was 21kN / m. Due to the lack of rigid support from mica, the mechanical properties were lower than in Example 2. The Shore A hardness was 57, indicating insufficient rigidity. The abrasion loss was 36mg, and the abrasion resistance basically met the standard. However, the lack of heat resistance and mechanical properties made the material unsuitable for high-temperature and high-load scenarios. This proves that the synergistic effect of epoxy resin and mica in composite micropowder A is better than that of a single component, which is an important improvement point of this technical solution.

[0052] Comparative Example 6: Please see Figure 1 The present invention provides a comparative scheme: replacing the composite micro powder B in Example 2 with a single butyl acrylate-styrene copolymer, while the rest is the same as in Example 2.

[0053] In the third stage of the preparation process, a single butyl acrylate-styrene copolymer was added during the mixing process, and the rest was the same as in Example 2.

[0054] Performance indicators Test Results Tensile strength 8.8MPa Tear strength 27kN / m Shore A hardness 63 Tensile strength retention rate at 200℃ for 72 hours 91% Wear amount 55mg In this comparative example, composite micropowder B was replaced with a single butyl acrylate-styrene copolymer, resulting in a significant decrease in wear resistance in the experimental data. The wear loss was 55 mg, a substantial increase from 32 mg in Example 2. Due to the lack of the low coefficient of friction characteristic of talc in composite micropowder B, the elasticity of the copolymer alone cannot effectively reduce friction loss, and long-term use is prone to wear on the sealing surface. The tensile strength was 8.8 MPa, and the tear strength was 27 kN / m. The mechanical properties were well maintained due to the interaction between modified nano-silica and composite micropowder A. The Shore A hardness was 63, and the rigidity was well-matched. The tensile strength retention rate at 200℃ for 72 h was 91%, and the heat resistance was stable. However, the insufficient wear resistance limited the application of the material in high-friction scenarios, proving that the composite synergy of butyl acrylate-styrene copolymer and talc in composite micropowder B is the key to improving wear resistance.

[0055] Comparative Example 7: Please see Figure 1 The present invention provides a comparative scheme: calcium carbonate is used to replace the modified nano-silica, composite micro powder A, and composite micro powder B in Example 2, and the amount added is 4+5+7=16 parts, while the rest is the same as in Example 2.

[0056] The preparation steps involve adding calcium carbonate in the second stage of mixing, and the rest is the same as in Example 2.

[0057] Performance indicators Test Results Tensile strength 5.8MPa Tear strength 16kN / m Shore A hardness 52 Tensile strength retention rate at 200℃ for 72 hours 60% Wear amount 75mg This comparative example uses conventional filler calcium carbonate, and its experimental data shows the lowest performance across all parameters. The tensile strength is 5.8 MPa, and the tear strength is 16 kN / m. The reinforcing effect of calcium carbonate is far inferior to that of the modified nano-silica and composite components in this technical solution, and the material's mechanical properties cannot meet sealing requirements. The Shore A hardness is 52, indicating insufficient rigidity and easy deformation. The tensile strength retention rate after 72 hours at 200℃ is only 60%, showing that calcium carbonate lacks a heat barrier effect, leading to rapid aging at high temperatures. The wear loss is 75 mg, indicating the worst wear resistance, and the sealing surface is prone to wear and failure. Compared with Example 2, this technical solution demonstrates that its composition system is significantly superior to conventional filler solutions in the prior art.

[0058] Comparative Example 8: Please see Figure 1 The present invention provides a comparative scheme: the modified nano-silica is added only in the third stage of mixing in the preparation method, and the rest is the same as in Example 2.

[0059] Performance indicators Test Results Tensile strength 7.2MPa Tear strength 23kN / m Shore A hardness 59 Tensile strength retention rate at 200℃ for 72 hours 83% Wear amount 40mg The modified nano-silica in this comparative example was added in the wrong order (added in the third stage of mixing), resulting in a significant decrease in experimental data compared to Example 2. The tensile strength was 7.2 MPa, and the tear strength was 23 kN / m. This was because the matrix had already initially bonded with other fillers during the third stage of mixing, preventing the modified nano-silica from dispersing sufficiently, leading to poor interfacial bonding and weakened reinforcing effect. The Shore A hardness was 59, indicating a decrease in rigidity. The tensile strength retention rate at 200℃ for 72 hours was 83%, with uneven dispersion causing insufficient local heat resistance. The abrasion loss was 40 mg, indicating a decrease in abrasion resistance due to insufficient mechanical support. This demonstrates that the order of addition of the modified nano-silica in this technical solution is crucial to ensuring its dispersibility and performance, distinguishing it from existing technologies that involve disordered addition.

[0060] Comparative Example 9: Please see Figure 1 The present invention provides a comparative scheme: except for the hydroxyapatite nanowires, the rest is the same as in Example 2.

[0061] Performance indicators Test Results Tensile strength 7.0MPa Tear strength 20kN / m Shore A hardness 56 Tensile strength retention rate at 200℃ for 72 hours 88% Wear amount 34mg The comparative example lacked hydroxyapatite nanowires, resulting in a significant decrease in mechanical properties in the experimental data. The tensile strength was 7.0 MPa and the tear strength was 20 kN / m, significantly lower than Example 2. This is because the lack of the skeletal support provided by the nanowire structure of hydroxyapatite nanowires reduced the efficiency of force transmission within the material, weakening its tensile and tear resistance. The Shore A hardness was 56, indicating insufficient rigidity, making the sealing ring prone to permanent deformation under pressure. The tensile strength retention rate after 72 hours at 200℃ was 88%, and since the heat resistance mainly depends on composite powder A, it was not significantly affected. The wear loss was 34 mg, indicating a slight decrease in wear resistance due to the weakened mechanical support, but it was still better than Comparative Example 3, which lacked composite powder B. These results demonstrate that hydroxyapatite nanowires are the key component in this technical solution for improving the mechanical strength of the composite material. Their synergistic effect with modified nano-silica and composite powder A is an important guarantee for achieving a balanced improvement in the material's mechanical properties and other properties.

[0062] Based on the performance data and preparation process of the above 4 sets of examples and 9 sets of comparative examples, it can be seen that the 4 sets of examples of this technical solution cover the lower limit, median, upper limit and middle value of the component weight parts, forming a complete performance gradient: Example 1 uses the lower limit of each component, and still achieves the basic performance of tensile strength of 8.5MPa, tensile strength retention rate of 85% at 200℃×72h, and wear loss of 45mg, meeting the sealing requirements of medium and low loads; Example 2, as the preferred solution, has a modified nano-silica grafting rate of 85%, an epoxy resin to mica mass ratio of 3:1 in composite micro powder A, and composite micro powder B The synergistic combination of 15% talc powder achieves optimal comprehensive performance with tensile strength of 10.2 MPa, tear strength of 32 kN / m, abrasion loss of 32 mg, and heat retention rate of 92%, making it suitable for medium-to-high load and high-temperature scenarios. Example 3 uses the upper limit of the component, further improving mechanical strength and heat resistance to tensile strength of 11.5 MPa and heat retention rate of 95%, which can cope with harsh environments under high load. Example 4 achieves performance balance with intermediate parameters, and the process parameters are compatible with conventional industrial equipment, facilitating large-scale production. The four examples together demonstrate that the component range and process parameter design of this technical solution are scientific and reasonable, can be flexibly adjusted according to actual needs, and can achieve performance indicators superior to existing technologies. From the technical defects revealed by the comparative examples, the nine sets of comparative examples, from different dimensions, confirm the innovative value of this technical solution: Comparative examples 1-9 respectively lack modified nano-silica, composite micro powder A, and composite micro powder B, resulting in targeted performance degradation. The lack of modified nano-silica leads to a decrease in tensile strength to 6.2 MPa and tear strength to 18 kN / m, the lack of composite micro powder A reduces the heat resistance retention rate to only 65%, and the lack of composite micro powder B... The wear loss was doubled to 60mg, proving that the three components are not simply additive, but form a synergistic system of mechanical reinforcement, heat resistance barrier, and anti-wear lubrication, which is different from the existing approach of modifying single or partial fillers. Comparative Example 4 used unmodified nano-silica to replace the modified product. Due to agglomeration and poor interfacial bonding, the tensile strength was only 6.5MPa and the wear loss was 48mg, highlighting the key role of KH-570 modification and ultrasonic pretreatment (150-250W, 20-40min) in solving the problem of nanofiller dispersion, filling the gap in the limited reinforcement effect of unmodified nanofillers in the existing technology. Comparative Examples 5-6 used single components to replace composite components. For example, replacing composite micropowder A with single epoxy resin reduced the heat resistance retention rate to 68%, and replacing composite micropowder B with single copolymer was also problematic. The wear loss was increased to 55 mg, demonstrating that the composite design of epoxy resin and mica, butyl acrylate and styrene copolymer with talc can exert an excellent synergistic effect, breaking through the performance bottleneck of single components in existing technologies. Comparative Example 7 used conventional filler calcium carbonate, which had the lowest performance in all aspects (tensile strength 5.8 MPa, heat retention rate 60%, wear loss 75 mg), directly proving that the composition system of this technical solution is significantly better than the traditional filler solution. Comparative Example 8 had tensile strength reduced to 7.2 MPa and heat retention rate reduced to 83% due to the incorrect order of addition of modified nano silica (added in the third stage of mixing). This shows that the staged mixing process design of this solution (adding modified nano silica in the second stage) is the key to ensuring filler dispersion and performance, correcting the performance fluctuation problem caused by disordered addition in existing technologies. In summary, compared with existing conventional solutions, this technical solution improves tensile strength by more than 30%, heat retention by more than 25%, and reduces wear by more than 40%. Moreover, the process is controllable and the raw materials are readily available, making it widely applicable to sealing needs in various fields such as automobiles, hydraulics, and pipelines. It provides an industrializable technical path for upgrading the performance of silicone rubber sealing ring materials.

[0063] To further illustrate the beneficial technical effects of the silicone rubber composite materials for sealing rings and their preparation methods according to the embodiments of the present invention, relevant performance tests were conducted on the silicone rubber composite materials for sealing rings and their preparation methods according to Examples 1-4 and Comparative Examples 1-9; the test methods are as follows: 1. Tensile strength test Sample preparation: The silicone rubber composite material was cut into type 1 dumbbell-shaped samples with an effective length of 25 mm, an end width of 10 mm, a width of 4 mm for the parallel middle part, and a thickness of 2 mm. Five parallel samples were prepared for each group. Test preparation: Place the sample in an environment with a temperature of 23℃ and a relative humidity of 50% for 24 hours to ensure that the sample is stable; Test procedure: Fix both ends of the specimen to the upper and lower clamps of the tensile testing machine, adjust the clamp spacing until the specimen is naturally straight and without pretension, set the tensile rate to 500 mm / min, start the equipment to perform tensile testing until the specimen breaks. Data calculation: Record the maximum tensile force when the specimen breaks, and calculate the tensile strength according to the formula "tensile strength = maximum tensile force / cross-sectional area of ​​the parallel part in the middle of the specimen". Take the average value of 5 parallel specimens as the final result, and the unit is MPa.

[0064] 2. Tear strength test Sample preparation: The silicone rubber composite material was cut into right-angle tear test specimens with a length of 75 mm, a width of 25 mm, and a thickness of 2 mm. A right-angle cut with a depth of 12.5 mm was made in the middle of the width direction of the specimen. Five parallel specimens were prepared in each group. Test preparation: Same environmental placement conditions as for tensile strength testing; Test procedure: Fix the uncut end of the specimen to the upper clamp of the tensile testing machine, and fix the two sides of the cut end to the lower clamp respectively, ensuring that the cut direction of the specimen is consistent with the tensile direction. Set the tensile rate to 500 mm / min, start the equipment to perform tensile testing until the specimen is completely torn along the cut. Data calculation: Record the maximum tear force during the tearing process of the sample, calculate the tear strength according to the formula "tear strength = maximum tear force / sample thickness", and take the average value of 5 parallel samples as the final result, with the unit being kN / m.

[0065] 3. Shore A hardness test Sample preparation: The silicone rubber composite material was made into circular samples with a diameter of 50 mm and a thickness of 6 mm, and 3 parallel samples were prepared for each group. Test preparation: Place the sample in an environment with a temperature of 23℃ and a relative humidity of 50% for 24 hours to ensure that the Shore A hardness tester is calibrated. Test procedure: Place the sample stably on the horizontal test platform to avoid deformation or movement of the sample. Align the hardness tester indenter vertically with the sample surface and apply pressure until the indenter is in complete contact with the sample without any additional pressure. Hold for 15 seconds and then read the hardness value. Data calculation: Five points were tested at different locations for each sample. The maximum and minimum values ​​were removed and the average value was taken. The average value of three parallel samples was taken as the final Shore A hardness result, which is unitless.

[0066] 4. Tensile strength retention rate test at 200℃ for 72 hours Initial strength test: The initial tensile strength of a group of specimens is tested according to the "Tensile Strength Test" method and recorded as S0; Aging treatment: Place another set of samples of the same specifications into the aging chamber, set the aging temperature to 200℃, and the aging time to 72h. During the aging process, ensure that the temperature inside the aging chamber is uniform and there is no local overheating. Strength test after aging: After aging, the sample is taken out and cooled in an environment of 23℃ and 50% relative humidity for 24 hours. Then, its tensile strength is tested according to the "Tensile Strength Test" method and recorded as S1. Data calculation: The retention rate was calculated according to the formula "tensile strength retention rate = (S1 / S0) × 100%", and the average value of 5 parallel specimens was taken as the final result, in units of .

[0067] 5. Wear resistance test (wear loss test) Sample preparation: The silicone rubber composite material was cut into circular samples with a diameter of 30 mm and a thickness of 5 mm. Three parallel samples were prepared for each group. Before the test, the sample surface was cleaned with ethanol and placed in an environment with a temperature of 23℃ and a relative humidity of 50% for 12 h. The initial mass of the sample was weighed using an analytical balance (accuracy 0.1 mg) and recorded as m0. Test preparation: Install the grinding wheel (silicon carbide grinding wheel, 80 mesh) of the rotary roller abrasion mill in place, adjust the contact pressure between the grinding wheel and the sample to 10N, and set the grinding wheel speed to 200r / min; Test procedure: Fix the sample on the sample stage of the abrasion machine, ensuring that the sample is in perpendicular contact with the grinding wheel, start the equipment, set the abrasion time to 1 hour, keep the grinding wheel clean and free of impurities during the abrasion process; Data Calculation: After the wear is completed, the sample is taken out, the surface residual wear debris is cleaned with ethanol, and the sample mass is weighed after drying and recorded as m1. The wear amount is calculated according to the formula "wear amount = m0 - m1". The average value of 3 parallel samples is taken as the final result, and the unit is mg.

[0068] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific technical solutions or characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A silicone rubber composite material for sealing rings, characterized by, The methyl vinyl silicone rubber 80-120 parts, fumed white carbon black 20-35 parts, hydroxyapatite nanowires 3-8 parts, polytetrafluoroethylene micro powder 2-6 parts, silane coupling agent 1-4 parts, peroxide crosslinking agent 0.5-2.5 parts, modified nano silicon dioxide 2-6 parts, composite micro powder A 3-8 parts, and composite micro powder B 4-9 parts.

2. The silicone rubber composite for sealing rings according to claim 1, characterized by, The modified nano silicon dioxide is KH-570 modified nano silicon dioxide with a particle size of 20-40 nm, a KH-570 grafting modification rate of ≥80%, and ultrasonic dispersion pretreatment.

3. The silicone rubber composite for sealing rings according to claim 1, characterized by, The composite micro powder A is an epoxy resin-mica composite micro powder, wherein the epoxy resin is a bisphenol A type epoxy resin, the mass ratio of the epoxy resin to the curing agent diamino diphenyl methane is 100:25-35, the mass ratio of the epoxy resin to mica is 2:1-4:1, the particle size is 1-5 μm, and the epoxy resin is compounded with mica after curing by the curing agent.

4. The silicone rubber composite for sealing rings according to claim 1, characterized by, The composite micro powder B is a butyl acrylate-styrene copolymer-talc composite powder, wherein the mass ratio of butyl acrylate to styrene is 1.8:1-2.2:1, the mass fraction of talc is 10%-20%, and the particle size is 0.8-4 μm.

5. The silicone rubber composite for sealing rings according to claim 1, characterized by, The hydroxyapatite nanowires have a diameter of 50-100 nm and an aspect ratio of 20-50; the polytetrafluoroethylene micro powder has a particle size of 0.5-2 μm and is low molecular weight polytetrafluoroethylene.

6. The silicone rubber composite for sealing rings according to claim 1, characterized by, The mass fraction of vinyl groups in the methyl vinyl silicone rubber is 0.15-0.25%; the silane coupling agent is γ-glycidyl ether oxypropyl trimethoxysilane, and the peroxide crosslinking agent is 2,5-dimethyl-2,5-di-tert-butyl peroxide hexane.

7. A process for the production of a silicone rubber composite material for sealing rings as claimed in any one of claims 1 to 6, characterized in that The method comprises the following steps: Preparation of the composite micro powder A: Bisphenol A type epoxy resin and diamino diphenyl methane are mixed in a mass ratio of 100:25-35, stirred and reacted at a temperature of 120-140 ℃ and a rotation speed of 80-100 r / min for 2-3 h, crushed to a particle size of 1-5 μm after cooling, and then mixed with mica in a mass ratio of 2:1-4:1, stirred and compounded at a temperature of 80-100 ℃ and a rotation speed of 100-150 r / min for 30-60 min, and cooled to obtain the composite micro powder A; S1: Preparation of the modified nano silicon dioxide: Nano silicon dioxide is dispersed in anhydrous ethanol to prepare a dispersion liquid with a concentration of 3-6 mg / mL, and 0.5-1.2 times the mass of KH-570 is added, stirred and reacted at a temperature of 50-70 ℃ and a rotation speed of 100-150 r / min for 3-5 h, washed with ethanol for 2-3 times after filtration, dried at a vacuum degree of 0.08-0.1 MPa and a temperature of 60-80 ℃ for 4-6 h, and modified nano silicon dioxide is obtained; S2: Plastication: The methyl vinyl silicone rubber is put into a plasticator, plasticated at a temperature of 85-95 ℃ and a rotation speed of 35-45 r / min for 6-8 min; S3: First stage mixing: adding fumed white carbon black and silane coupling agent to the material obtained in step 2, mixing at a temperature of 105-115℃ and a rotation speed of 28-38r / min for 18-22min to obtain a first mixture; S4: Second stage mixing: adding the modified nano-silica prepared in S1 and the composite micro-powder A to the first mixture, mixing at a temperature of 95-105℃ and a rotation speed of 25-30r / min for 8-12min to obtain a second mixture; S5: Third stage mixing: adding hydroxyapatite nanowires, the composite micro-powder B and polytetrafluoroethylene micro-powder to the second mixture, mixing at a temperature of 90-100℃ and a rotation speed of 22-32r / min for 12-18min to obtain a third mixture; S6: Crosslinking agent mixing: adding a peroxide crosslinking agent to the third mixture, mixing at a temperature of 75-85℃ and a rotation speed of 18-28r / min for 8-12min to obtain a rubber compound; S7: Vulcanization molding: placing the rubber compound into a mold, vulcanizing at a temperature of 165-175℃ and a pressure of 6-9MPa for 12-18min, and then secondarily vulcanizing at a temperature of 190-200℃ for 2.5-3.5h to obtain a silicone rubber composite material.

8. The production method according to claim 7, characterized by, The interval for adding the hydroxyapatite nanowires, the composite micro-powder B and the polytetrafluoroethylene micro-powder in S5 is 2-4min, and after adding each material, stirring is performed for 1.5-2.5min before adding the next material.

9. The preparation method according to claim 7, characterized in that, The preheating temperature of the mold in S7 is 160-170℃, and the preheating time is 5-8min; the power of the ultrasonic dispersion pretreatment in S1 is 150-250W, and the time is 20-40min.

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