Heat-resistant and infrared-resistant rubber sealing element and preparation method thereof

Abstract

The invention relates to the technical field of sealing element processing, in particular to a heat-resistant and infrared-resistant rubber sealing element and a preparation method thereof. The high-performance silicone rubber is prepared from the following raw materials in parts by weight: 100 parts of silicone rubber, 20-30 parts of fumed silica, 5-10 parts of fluorinated silicone rubber, 3-5 parts of nano copper oxide, 2-4 parts of nano zinc sulfide, 3-5 parts of hexamethyldisilazane, 3-6 parts of hydroxyl silicone oil, 3-5 parts of a heat stabilizer and 0.5-1 part of a peroxide vulcanizing agent, the sealing element prepared according to the formula still keeps excellent elasticity and sealing performance in a long-term high-temperature infrared environment, hardening and cracking are reduced, and the service life is greatly prolonged.

Description

Technical Field

[0001] This application relates to the field of sealing component processing technology, and more specifically, to a heat-resistant and infrared-resistant rubber seal and its preparation method. Background Technology

[0002] An infrared lamp is a type of infrared therapy device that can promote recovery from skin infections, ulcers, postoperative wounds, and burns. Its working principle involves using infrared radiation to penetrate clothing and reach the affected area. Through photothermal conversion, it raises the temperature of muscle and subcutaneous tissues, thereby accelerating local blood circulation, promoting cell metabolism, relieving pain, and improving tissue nutrition. During treatment, the thermal effect of infrared rays can also relax muscle tissue, producing a massage-like auxiliary therapeutic effect.

[0003] Existing infrared therapy devices typically consist of a lamp body, a reflector, a circuit control system, and sealing components. The sealing components are mostly made of silicone rubber, and their function is to effectively isolate the internal electronic components of the lamp body from the external environment, preventing the intrusion of moisture and dust, and ensuring the safe operation of the equipment in a medical environment. However, under long-term continuous operation, the sustained high-temperature radiation generated by the infrared lamp will subject the silicone rubber seals to a prolonged thermo-oxidative aging environment. Under the combined effects of high temperature and infrared radiation, the silicone rubber molecular chains are prone to irreversible degradation reactions such as breakage and cross-linking, leading to aging phenomena such as hardening, cracking, and decreased elasticity in the seals. This, in turn, can cause problems such as seal failure, moisture leakage, and reduced insulation performance, not only affecting the service life of the therapy device but also potentially posing electrical safety hazards. Summary of the Invention

[0004] To address the issue of silicone rubber seals aging easily under long-term use conditions of high temperature and infrared radiation, this application provides a heat-resistant and infrared-resistant rubber seal and its preparation method.

[0005] In a first aspect, this application provides a heat-resistant and infrared-resistant rubber seal, which adopts the following technical solution: A heat-resistant and infrared-resistant rubber seal is prepared from the following raw materials in parts by weight: 100 parts of silicone rubber 20-30 parts of fumed silica 5-10 parts of fluorosilicone rubber 3-5 parts of nano copper oxide 2-4 parts of nano zinc sulfide 3-5 parts of hexamethyldisilazane 3-6 parts of hydroxy silicone oil 3-5 parts heat stabilizer Peroxide vulcanizing agent 0.5-1 part The silicone rubber is composed of methyl vinyl silicone rubber and phenyl vinyl silicone rubber.

[0006] By adopting the above technical solutions, the rubber seals possess excellent heat resistance and infrared resistance, enabling long-term use in high-temperature infrared environments while maintaining good tensile strength and low compression set. Firstly, phenyl vinyl silicone rubber and methyl vinyl silicone rubber are used together as the matrix. The introduction of phenyl groups effectively improves the rigidity and thermal stability of the molecular chain. The blending of fluorosilicone rubber utilizes the strong electronegativity of fluorine atoms to form CF bonds with higher chemical bond energy in the molecular chain segments, significantly enhancing the material's resistance to heat and oxygen aging and its chemical inertness. The synergistic effect of these two components allows the seals to maintain the integrity of the molecular chain structure in continuous high-temperature environments, effectively delaying thermal degradation reactions. Secondly, the added nano-copper oxide and nano-zinc sulfide, as functional fillers, form a uniformly dispersed nano-shielding layer in the rubber matrix. Through absorption and reflection mechanisms, this significantly reduces the penetration depth of infrared radiation energy into the rubber interior, minimizing the damage to the molecular chain caused by photothermal effects, while also inhibiting free radical reactions during heat and oxygen aging.

[0007] Fumed silica forms a physical cross-linked network with silicone rubber molecular chains through hydrogen bonding, which not only improves the tensile strength of the material but also acts as a supporting skeleton at high temperatures, preventing the material from deforming and failing due to thermal softening. Furthermore, hexamethyldisilazane and hydroxyl silicone oil act as structure control agents, effectively regulating the activity of hydroxyl groups on the surface of fumed silica, improving its dispersibility and interfacial compatibility in silicone rubber, avoiding structural phenomena during processing, ensuring the flowability of the rubber compound and the stability of the molding process, and participating in the cross-linking reaction during vulcanization to form a more stable three-dimensional network structure. Combined with an optimized ratio of peroxide vulcanizing agent and heat stabilizer, the seals achieve suitable cross-linking density and efficient heat oxidation protection. Even under long-term continuous operation, they maintain excellent elastic recovery, reduce hardening cracking, maintain reliable moisture sealing, and thus extend the service life of the seals.

[0008] Preferably, the weight ratio of the methyl vinyl silicone rubber to the phenyl vinyl silicone rubber is (5-9):2.

[0009] By adopting the above technical solution and optimizing the weight ratio of methyl vinyl silicone rubber and phenyl vinyl silicone rubber, the phenyl groups form an appropriate crosslinking density and chain segment rigidity in the molecular chain, thereby increasing the glass transition temperature of the seal and further improving its thermal and oxygen stability and resistance to infrared radiation. Simultaneously, methyl vinyl silicone rubber, as the matrix, retains its excellent low-temperature elasticity and good processing fluidity, ensuring that the rubber compound has appropriate Mooney viscosity and vulcanization characteristics during mixing and molding, avoiding process defects such as hardening, poor fluidity, and incomplete vulcanization caused by excessive phenyl content.

[0010] Preferably, the methyl vinyl silicone rubber is composed of methyl vinyl silicone rubber I, methyl vinyl silicone rubber II, and methyl vinyl silicone rubber III in a weight ratio of (3-6):(2-5):1; The degree of polymerization of methyl vinyl silicone rubber I is 1000-3000, the vinyl content is 0.1-0.3 mol%, and the viscosity at 25℃ is 7000-10000 mPa·s; Methyl vinyl silicone rubber II has a degree of polymerization of 4000-8000, a vinyl content of 0.05-0.1 mol%, and a viscosity of 15000-20000 mPa·s at 25°C. The degree of polymerization of methyl vinyl silicone rubber III is 8000-10000, the vinyl content is 0.08-0.2 mol%, and the viscosity at 25℃ is 30000-50000 mPa·s.

[0011] By adopting the above technical solution, methyl vinyl silicone rubber III with high polymerization degree and moderate vinyl content serves as a long-chain backbone, forming a main crosslinking network that runs through the entire system after vulcanization. This endows the seal with excellent resilience and dimensional stability at high temperatures, effectively suppressing thermal creep. Methyl vinyl silicone rubber II with medium polymerization degree but the lowest vinyl content acts as a flexible chain segment regulator. Its low crosslinking density region forms a microphase separation structure in space, which can absorb and dissipate local thermal stress generated by infrared radiation, while improving the tear strength and elongation at break of the material. Methyl vinyl silicone rubber I with low polymerization degree of 1000-3000 and the highest vinyl content serves as a crosslinking active center. Its short-chain structure and high reactivity ensure the sufficiency and uniformity of the crosslinking reaction during vulcanization, avoiding vulcanization reversion or crosslinking blind spots caused by uneven composition. When these three components are blended in a specific ratio, they form a composite structure of interpenetrating and semi-interpenetrating networks at the microscopic level. This ensures that the rubber compound has a suitable processing viscosity during the mixing stage and also creates a gradient characteristic in the crosslinking density distribution of the vulcanizate. This structure effectively buffers thermal shock under infrared thermal radiation through the synergistic relaxation effect between different chain segments, thereby enhancing the material's thermo-oxidative aging activation energy. Ultimately, this blended system further reduces the compression set of the seal under continuous infrared irradiation to below 12%, increases the tensile strength retention rate to over 90%, and reduces the hardness change rate after thermal aging to below 3 degrees. Simultaneously, it enhances the absorption and shielding efficiency of the seal against high-frequency infrared radiation, extending its service life in infrared therapy devices.

[0012] Preferably, the phenyl vinyl silicone rubber has a molecular weight of 50,000 to 150,000 and a phenyl content of 1% to 5%.

[0013] By adopting the above technical solutions, a molecular weight of 5-150,000 ensures good compatibility between phenyl vinyl silicone rubber and the compounded methyl rubber system, moderate Mooney viscosity, uniform mixing and dispersion, and sufficient vulcanization and crosslinking, thereby increasing the crosslinking density and enhancing dimensional stability and resistance to thermal creep. A phenyl content of 1-5% improves molecular chain rigidity and thermo-oxidative degradation activation energy through conjugation, reducing the surface temperature rise of the seal under infrared radiation by 5-8°C, achieving an infrared absorption rate of over 85%. It forms a multiple shielding mechanism with nano-copper oxide and zinc sulfide, effectively weakening photothermal aging. This content range avoids insufficient modification due to excessively low phenyl content, while overcoming processing difficulties and increased brittleness caused by excessively high content. It also synergistically improves filler dispersion with hydroxyl silicone oil, enhancing the reinforcing effect of silica. Ultimately, this extends the service life of the seal while maintaining good molding processability.

[0014] Preferably, the fluorosilicone rubber is pretreated by the following method: According to the weight parts, 5-7 parts of γ-trifluoropropylmethylpolysiloxane and 1-2 parts of tetrafluoropropylene rubber are mixed evenly, heated to 100-110℃, and then 3-6 parts of triallyl isocyanurate are added and stirred evenly to obtain pretreated fluorosilicone rubber.

[0015] By adopting the above technical solutions, fluorosilicone rubber can improve the thermal aging performance of seals. However, its poor compatibility with silicone rubber makes the finished product prone to cracking. In this application, γ-trifluoropropylmethylpolysiloxane and tetrafluoropropylene rubber are premixed at 100-110℃. The thermal activation effect promotes the interdiffusion of molecular chains of different fluorinated polymers and forms a pre-dispersed micro-phase structure, effectively solving the problem of poor compatibility between tetrafluoropropylene rubber and silicone rubber. Triallyl isocyanurate fully penetrates to the interface of each component under preheating conditions. Its high-functionality allyl group acts as a crosslinking bridge during peroxide vulcanization, reacting with the vinyl groups of silicone rubber and the unsaturated bonds of fluororubber to form a high-density interpenetrating network, thereby increasing the crosslinking density, improving the thermal aging and infrared resistance performance of the seals, and extending the service life of the seals under infrared irradiation.

[0016] Preferably, the tetrafluoropropylene rubber is a tetrafluoroethylene-propylene polymer with a number average molecular weight of 50,000-100,000, a tetrafluoroethylene unit content of 50-60 mol%, and a propylene unit content of 40-50 mol%.

[0017] By adopting the above technical solution, the high proportion of tetrafluoroethylene units introduces high-bond-energy CF bonds to enhance thermal stability, while the propylene units provide flexibility to alleviate infrared thermal stress and can form a dense interpenetrating network with triallyl isocyanurate and silicone rubber vinyl groups, improving resistance to heat and oxygen aging and infrared radiation. Simultaneously, it ensures suitable Mooney viscosity for the fluorosilicone rubber, uniform mixing and dispersion, maintains excellent mechanical properties and elasticity of the sealant, ensures stable molding processes and long-term sealing performance, and extends service life.

[0018] Preferably, the peroxide vulcanizing agent includes at least one of benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, and di-tert-butyl peroxide.

[0019] By adopting the above technical solution, in conjunction with triallyl isocyanurate, the synchronous cross-linking of silicone rubber and fluororubber molecules is achieved, forming a stable three-dimensional network. This enhances the heat and oxygen aging resistance and compression resilience of the seal, ensures that the vulcanization process is controllable and that no acidic byproducts are released, and makes the cross-linking network of the seal stable under continuous infrared irradiation.

[0020] Preferably, the hydroxyl content of the hydroxyl silicone oil is 5-10 wt%.

[0021] By adopting the above technical solution, hydroxyl silicone oil with a hydroxyl content of 5-10wt% serves as a highly efficient structure control agent. Through hydrogen bonding, it shields the surface activity of fumed silica, preventing the rubber compound from becoming structured. This reduces Mooney viscosity during mixing and improves the uniformity of filler dispersion. Its hydroxyl groups participate in the peroxide vulcanization reaction, forming flexible crosslinking points, optimizing the crosslinking density distribution, and enhancing the resilience and tear strength of the seals. At the same time, it avoids processing difficulties caused by too low a hydroxyl content and heat resistance degradation caused by too high a hydroxyl content, ensuring stable mechanical properties under infrared irradiation.

[0022] Preferably, the heat stabilizer is composed of nano-cerium oxide and nano-titanium dioxide in a weight ratio of 1:(2-5).

[0023] By adopting the above technical solution, nano-cerium oxide inhibits the chain reaction by capturing thermo-oxidative degradation free radicals, while nano-titanium dioxide reflects and shields infrared radiation energy. The combination of the two produces a synergistic effect, which reduces the thermal degradation rate of the seal under continuous infrared irradiation, maintains high tensile strength, and effectively extends its service life.

[0024] Secondly, this application provides a method for preparing a heat-resistant and infrared-resistant rubber seal, which adopts the following technical solution: A method for preparing a heat-resistant and infrared-resistant rubber seal includes the following preparation steps: S1. Plasticize the silicone rubber matrix at 80-90℃, raise the temperature to 110-120℃, and then add hydroxyl silicone oil, hexamethyldisilazane, fumed silica, nano copper oxide, zinc sulfide, heat stabilizer and fluorosilicone rubber for mixing. Cool down to 75-80℃, add peroxide vulcanizing agent and mix to obtain a mixture. S2. Place the mixture in an environment with a temperature of 170-180℃ and a pressure of 12-15MPa for 12-15 minutes, and then place it in an environment with a temperature of 200-220℃ for 1-2 hours to obtain heat-resistant and infrared-resistant rubber seals.

[0025] By adopting the above technical solution, in stage S1, the silicone rubber matrix is ​​plasticized and softened at 80-90℃, and mixed at 110-120℃ to promote the uniform dispersion of hydroxyl silicone oil and other additives and fillers. A vulcanizing agent is added at 75-80℃ to prevent premature cross-linking and ensure the processing stability of the rubber compound. In the two-stage vulcanization process of S2, rapid molding and initial cross-linking are achieved at 170-180℃ / 12-15MPa, and deep vulcanization at 200-220℃ further increases the cross-linking density, forming a stable three-dimensional network structure. The overall process is adapted to the characteristics of the raw material system, ensuring uniform dispersion of components such as nanofillers and fluorosilicone rubber, while also enhancing the synergistic effects of heat resistance and infrared resistance. This results in seals possessing excellent mechanical properties, resistance to thermo-oxidative aging, and infrared shielding capabilities, leading to good molding results and further extending the service life of the seals in high-temperature infrared environments.

[0026] In summary, this application has the following beneficial effects: 1. This application utilizes a blend of methyl vinyl silicone rubber and phenyl vinyl silicone rubber as the matrix. The phenyl groups enhance the rigidity and thermal stability of the molecular chain, while the addition of high-energy CF bonds through fluorosilicone rubber synergistically delays molecular chain degradation at high temperatures, improving resistance to heat and oxygen aging. Nano-copper oxide and zinc sulfide form a nano-shielding layer, reducing infrared radiation penetration and photothermal damage. Fumed silica constructs a physical cross-linking network, strengthening mechanical properties and high-temperature deformation resistance. Hexamethyldisilazane and hydroxyl silicone oil optimize filler dispersion and processing stability, participating in cross-linking to form a stable three-dimensional structure. With an optimized ratio of vulcanizing agent and heat stabilizer, the seal achieves suitable cross-linking density and highly efficient heat oxidation protection, maintaining excellent elasticity and sealing performance even under long-term high-temperature infrared conditions, reducing hardening cracks, and significantly extending service life. Detailed Implementation Example

[0027] Example 1

[0028] A heat-resistant and infrared-resistant rubber seal is prepared by the following method: S1. Plasticize 1000g of silicone rubber in a silicone rubber matrix at 80℃, raise the temperature to 110℃, and then add 30g of hydroxyl silicone oil, 30g of hexamethyldisilazane, 200g of fumed silica, 30g of nano copper oxide, 20g of zinc sulfide, 30g of heat stabilizer and 50g of fluorosilicone rubber for mixing. Cool down to 75℃, add 5g of peroxide vulcanizing agent (benzoyl peroxide) and mix to obtain a mixture. Silicone rubber is composed of methyl vinyl silicone rubber and phenyl vinyl silicone rubber in a weight ratio of 5:2. Methyl vinyl silicone rubber is composed of methyl vinyl silicone rubber I, methyl vinyl silicone rubber II, and methyl vinyl silicone rubber III in a weight ratio of 3:2:1; The degree of polymerization of methyl vinyl silicone rubber I is 1000, the vinyl content is 0.1 mol%, and the viscosity at 25°C is 7000 mPa·s. Methyl vinyl silicone rubber II has a degree of polymerization of 4000, a vinyl content of 0.05 mol%, and a viscosity of 15000 mPa·s at 25°C. The degree of polymerization of methyl vinyl silicone rubber III is 8000, the vinyl content is 0.08 mol%, and the viscosity at 25°C is 30000 mPa·s. The molecular weight of phenyl vinyl silicone rubber is 50,000, and the phenyl content is 1%. The hydroxyl content of the hydroxyl silicone oil is 5 wt%, and the molecular weight is 4000. The heat stabilizer is composed of nano-cerium oxide and nano-titanium dioxide in a weight ratio of 1:2; Fluorosilicone rubber is a tetrafluoroethylene-propylene polymer with a number average molecular weight of 50,000, a tetrafluoroethylene unit content of 50 mol%, and a propylene unit content of 40 mol%. S2. Place the mixture in an environment with a temperature of 170℃ and a pressure of 12MPa for 12 minutes, and then place it in an environment with a temperature of 200℃ for 1 hour to obtain a heat-resistant and infrared-resistant rubber seal.

[0029] Example 2

[0030] A heat-resistant and infrared-resistant rubber seal is prepared by the following method: S1. Plasticize 1000g of silicone rubber in a silicone rubber matrix at 85℃, raise the temperature to 115℃, and then add 45g of hydroxyl silicone oil, 40g of hexamethyldisilazane, 250g of fumed silica, 40g of nano copper oxide, 30g of zinc sulfide, 40g of heat stabilizer and 80g of fluorosilicone rubber for mixing. Cool down to 78℃, add 8g of peroxide vulcanizing agent (dicumyl peroxide) and mix to obtain a mixture. Silicone rubber is composed of methyl vinyl silicone rubber and phenyl vinyl silicone rubber in a weight ratio of 7:2. Methyl vinyl silicone rubber is composed of methyl vinyl silicone rubber I, methyl vinyl silicone rubber II, and methyl vinyl silicone rubber III in a weight ratio of 4.5:3.5:1; The degree of polymerization of methyl vinyl silicone rubber I is 2000, the vinyl content is 0.2 mol%, and the viscosity at 25°C is 9000 mPa·s. Methyl vinyl silicone rubber II has a degree of polymerization of 6000, a vinyl content of 0.08 mol%, and a viscosity of 18000 mPa·s at 25°C. The degree of polymerization of methyl vinyl silicone rubber III is 9000, the vinyl content is 0.1 mol%, and the viscosity at 25°C is 40000 mPa·s. The molecular weight of phenyl vinyl silicone rubber is 100,000, and the phenyl content is 3%. The hydroxyl content of the hydroxyl silicone oil is 8 wt%, and the molecular weight is 6000. The heat stabilizer is composed of nano-cerium oxide and nano-titanium dioxide in a weight ratio of 1:3; Fluorosilicone rubber is a tetrafluoroethylene-propylene polymer with a number average molecular weight of 80,000, a tetrafluoroethylene unit content of 55 mol%, and a propylene unit content of 45 mol%. S2. Place the mixture in an environment with a temperature of 175℃ and a pressure of 14MPa for 13 minutes, and then place it in an environment with a temperature of 210℃ for 1.5 hours to obtain a heat-resistant and infrared-resistant rubber seal.

[0031] Example 3

[0032] A heat-resistant and infrared-resistant rubber seal is prepared by the following method: S1. 1000g of silicone rubber is plasticized in a silicone rubber matrix at 90℃, heated to 120℃, and then 60g of hydroxyl silicone oil, 50g of hexamethyldisilazane, 300g of fumed silica, 50g of nano copper oxide, 40g of zinc sulfide, 50g of heat stabilizer and 100g of fluorosilicone rubber are added and mixed. The mixture is then cooled to 80℃, and 10g of peroxide vulcanizing agent (2,4-dichlorobenzoyl peroxide) is added and mixed to obtain a mixture. Silicone rubber is composed of methyl vinyl silicone rubber and phenyl vinyl silicone rubber in a weight ratio of 9:2. Methyl vinyl silicone rubber is composed of methyl vinyl silicone rubber I, methyl vinyl silicone rubber II, and methyl vinyl silicone rubber III in a weight ratio of 6:5:1; The degree of polymerization of methyl vinyl silicone rubber I is 3000, the vinyl content is 0.3 mol%, and the viscosity at 25°C is 10000 mPa·s. Methyl vinyl silicone rubber II has a degree of polymerization of 8000, a vinyl content of 0.1 mol%, and a viscosity of 20000 mPa·s at 25°C. The degree of polymerization of methyl vinyl silicone rubber III is 10,000, the vinyl content is 0.2 mol%, and the viscosity at 25°C is 50,000 mPa·s. The molecular weight of phenyl vinyl silicone rubber is 150,000, and the phenyl content is 5%. The hydroxyl content of the hydroxyl silicone oil is 10 wt%, and the molecular weight is 8000. The heat stabilizer is composed of nano-cerium oxide and nano-titanium dioxide in a weight ratio of 1:2; Fluorosilicone rubber is a tetrafluoroethylene-propylene polymer with a number average molecular weight of 100,000, a tetrafluoroethylene unit content of 60 mol%, and a propylene unit content of 50 mol%. S2. Place the mixture in an environment with a temperature of 180℃ and a pressure of 15MPa for 15 minutes, and then place it in an environment with a temperature of 220℃ for 2 hours to obtain a heat-resistant and infrared-resistant rubber seal.

[0033] Example 4

[0034] A heat-resistant and infrared-resistant rubber seal, the difference between this embodiment and Embodiment 1 is that the fluorosilicone rubber is pretreated by the following method: Mix 50g of γ-trifluoropropylmethylpolysiloxane and 10g of tetrafluoropropylene rubber evenly, heat to 100℃, then add 30g of triallyl isocyanurate and stir evenly to obtain pretreated fluorosilicone rubber.

[0035] Example 5

[0036] A heat-resistant and infrared-resistant rubber seal, the difference between this embodiment and Embodiment 1 is that the fluorosilicone rubber is pretreated by the following method: Mix 70g of γ-trifluoropropylmethylpolysiloxane and 20g of tetrafluoropropylene rubber evenly, heat to 110℃, then add 60g of triallyl isocyanurate and stir evenly to obtain pretreated fluorosilicone rubber.

[0037] Example 6

[0038] A heat-resistant and infrared-resistant rubber seal, the difference between this embodiment and embodiment 1 is that the methyl vinyl silicone rubber is composed of methyl vinyl silicone rubber I and methyl vinyl silicone rubber II.

[0039] Example 7

[0040] A heat-resistant and infrared-resistant rubber seal, the difference between this embodiment and embodiment 1 is that the methyl vinyl silicone rubber is methyl vinyl silicone rubber III. Comparative Example

[0041] Comparative Example 1 A rubber seal, the difference between this comparative example and Example 1 is that the silicone rubber is methyl vinyl silicone rubber.

[0042] Comparative Example 2 A rubber seal, the difference between this comparative example and Example 1 is that the silicone rubber is phenyl vinyl silicone rubber.

[0043] Comparative Example 3 A rubber seal, the difference between this comparative example and Example 1 is that no nano copper oxide is added.

[0044] Comparative Example 4 A rubber seal, the difference between this comparative example and Example 1 is that diphenylsilanediol is used instead of hexamethyldisilazane. Test methods / detection methods

[0045] Tensile strength: The test was conducted in accordance with GB / T 528-2009 "Determination of tensile properties of vulcanized rubber or thermoplastic rubber", using a dumbbell-shaped sample at a speed of 100 mm / min. Compression set: Refer to GB / T 7759.1-2015 (Determination of compression set of vulcanized rubber or thermoplastic rubber - Part 1: Under normal and high temperature conditions), the sample is type A, the test temperature is 120℃, and the test time is 100h. Thermo-oxidative aging performance: The finished products obtained in Examples 1-7 and Comparative Examples 1-4 were placed in a hot air aging chamber at 150°C and left to stand for 168 hours before their tensile strength was tested.

[0046] Infrared radiation resistance test: The finished infrared lamps prepared in Examples 1-7 and Comparative Examples 1-4 were placed in an infrared lamp simulation device (wavelength 10μm, radiation intensity 500W / m², temperature 120℃) and left to stand for 1000 hours. The surface was observed for cracking. If no cracks appeared, the tensile strength was tested. The experimental data are shown in Table 1. Table 2 Examples 1-7 and Comparative Examples 1-4

[0047] The experimental data above show that the seal made by the formula of this application has good heat aging resistance and infrared resistance, enabling the seal to be used for a long time in a high temperature infrared environment.

[0048] By comparing Example 1 with Comparative Examples 1-4, it is shown that this application achieves improvements in tensile strength, thermo-oxidative aging performance, and resistance to infrared radiation, while reducing compression set, through the synergistic effect of the compounding of methyl vinyl silicone rubber and phenyl vinyl silicone rubber, the composite shielding layer of nano copper oxide and zinc sulfide, and the hexamethyldisilazane structure control agent.

[0049] Comparing Examples 1 and 4-5, it is evident that pretreatment of fluorosilicone rubber using the method described in this application effectively improves the compatibility between fluorosilicone rubber and silicone rubber and forms a high-density interpenetrating network, thereby enhancing its thermo-oxidative aging performance, resistance to infrared radiation, and tensile strength, while reducing its compression set.

[0050] Comparing Examples 1 and 6-7, it is shown that the crosslinked network formed by compounding methyl vinyl silicone rubber I, methyl vinyl silicone rubber II and methyl vinyl silicone rubber III in a specific ratio is beneficial to improving the heat resistance and infrared resistance of the seal, and is beneficial to maintaining a low compression set under continuous infrared irradiation.

[0051] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A heat-resistant and infrared-resistant rubber seal, characterized in that, It is prepared from the following raw materials in parts by weight: 100 parts of silicone rubber 20-30 parts of fumed silica 5-10 parts of fluorosilicone rubber 3-5 parts of nano copper oxide 2-4 parts of nano zinc sulfide 3-5 parts of hexamethyldisilazane 3-6 parts of hydroxy silicone oil 3-5 parts heat stabilizer Peroxide vulcanizing agent 0.5-1 part The silicone rubber is composed of methyl vinyl silicone rubber and phenyl vinyl silicone rubber.

2. The heat-resistant and infrared-resistant rubber seal according to claim 1, characterized in that: The weight ratio of the methyl vinyl silicone rubber to the phenyl vinyl silicone rubber is (5-9):

2.

3. The heat-resistant and infrared-resistant rubber seal according to claim 2, characterized in that: The methyl vinyl silicone rubber is composed of methyl vinyl silicone rubber I, methyl vinyl silicone rubber II and methyl vinyl silicone rubber III in a weight ratio of (3-6):(2-5):1; The degree of polymerization of methyl vinyl silicone rubber I is 1000-3000, the vinyl content is 0.1-0.3 mol%, and the viscosity at 25℃ is 7000-10000 mPa·s; Methyl vinyl silicone rubber II has a degree of polymerization of 4000-8000, a vinyl content of 0.05-0.1 mol%, and a viscosity of 15000-20000 mPa·s at 25°C. The degree of polymerization of methyl vinyl silicone rubber III is 8000-10000, the vinyl content is 0.08-0.2 mol%, and the viscosity at 25℃ is 30000-50000 mPa·s.

4. The heat-resistant and infrared-resistant rubber seal according to claim 2, characterized in that: The phenyl vinyl silicone rubber has a molecular weight of 50,000-150,000 and a phenyl content of 1-5%.

5. The heat-resistant and infrared-resistant rubber seal according to claim 1, characterized in that, The fluorosilicone rubber is pretreated by the following method: According to the weight parts, 5-7 parts of γ-trifluoropropylmethylpolysiloxane and 1-2 parts of tetrafluoropropylene rubber are mixed evenly, heated to 100-110℃, and then 3-6 parts of triallyl isocyanurate are added and stirred evenly to obtain pretreated fluorosilicone rubber.

6. The heat-resistant and infrared-resistant rubber seal according to claim 5, characterized in that: The tetrafluoropropylene rubber is a tetrafluoroethylene-propylene polymer with a number average molecular weight of 50,000-100,000, a tetrafluoroethylene unit content of 50-60 mol%, and a propylene unit content of 40-50 mol%.

7. The heat-resistant and infrared-resistant rubber seal according to claim 1, characterized in that: The peroxide vulcanizing agent includes at least one of benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, and di-tert-butyl peroxide.

8. The heat-resistant and infrared-resistant rubber seal according to claim 1, characterized in that: The hydroxyl content of the hydroxyl silicone oil is 5-10 wt%.

9. The heat-resistant and infrared-resistant rubber seal according to claim 1, characterized in that: The heat stabilizer is composed of nano-cerium oxide and nano-titanium dioxide in a weight ratio of 1:(2-5).

10. A method for preparing a heat-resistant and infrared-resistant rubber seal as described in any one of claims 1-9, characterized in that, The preparation steps include the following: S1. Plasticize the silicone rubber matrix at 80-90℃, raise the temperature to 110-120℃, and then add hydroxyl silicone oil, hexamethyldisilazane, fumed silica, nano copper oxide, zinc sulfide, heat stabilizer and fluorosilicone rubber for mixing. Cool down to 75-80℃, add peroxide vulcanizing agent and mix to obtain a mixture. S2. Place the mixture in an environment with a temperature of 170-180℃ and a pressure of 12-15MPa for 12-15 minutes, and then place it in an environment with a temperature of 200-220℃ for 1-2 hours to obtain heat-resistant and infrared-resistant rubber seals.

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