Flame-retardant high-temperature-resistant high-strength silicone rubber and preparation method thereof

Abstract

The invention relates to the technical field of silicone rubber materials, and particularly discloses flame-retardant, high-temperature-resistant and high-strength silicone rubber and a preparation method thereof. The flame-retardant high-temperature-resistant high-strength silicone rubber comprises a component A and a component B. The component A comprises the following raw materials in parts by weight: 100 parts of base rubber, 20-30 parts of modified fumed nano-silica, 1-5 parts of cerium oxide, 1-3 parts of ferric oxide and 5-15 parts of a flame retardant, and the flame retardant comprises aluminum hydroxide and melamine cyanurate in a mass ratio of 10: (2-4); and the component B is prepared from 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexane. The flame retardance, high temperature resistance and high strength of the silicone rubber can be improved at the same time, and the application scene of the silicone rubber can be expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of silicone rubber materials, and in particular to a flame-retardant, high-temperature resistant and high-strength silicone rubber and a preparation method thereof. Background Art

[0002] Silicone rubber has excellent properties such as good resistance to high and low temperatures, ozone, and weather resistance, and is widely used in various fields of the national economy. Due to its excellent weather and ozone resistance, silicone rubber has broad application prospects in industries such as the automotive industry, electronic packaging, and aerospace.

[0003] In the related art, a silicone rubber material with strong weather resistance is disclosed, and its raw materials include the following weight components: 30-60 parts of silicone rubber, 10-15 parts of hydrogenated nitrile rubber, 10-12 parts of capping silicone rubber, 10-13 parts of bisphenol A solid epoxy resin, 3-4 parts of flame retardant, 1-2 parts of antioxidant, and 3-4 parts of vulcanizing agent.

[0004] The above silicone rubber material has high weather resistance. However, in some application environments, the silicone rubber material is also required to have excellent flame retardant properties, high temperature resistance properties, and high strength. Therefore, it is of great positive significance to study silicone rubber with flame retardancy, high temperature resistance, and high strength. Summary of the Invention

[0005] In order to improve the flame retardant, high temperature resistant, and high strength properties of silicone rubber, the present application provides a flame-retardant, high-temperature resistant and high-strength silicone rubber and a preparation method thereof.

[0006] In a first aspect, a flame-retardant, high-temperature resistant and high-strength silicone rubber provided by the present application adopts the following technical solution: A flame-retardant, high-temperature resistant and high-strength silicone rubber includes component A and component B. The component A includes the following raw materials in parts by weight: 100 parts of base rubber, 20-30 parts of modified fumed nano-silica, 1-5 parts of cerium oxide, 1-3 parts of ferric oxide, 5-15 parts of flame retardant, and the flame retardant includes aluminum hydroxide and melamine cyanurate with a mass ratio of 10:(2-4); the component B includes 2,5-dimethyl-2,5-di-tert-butylperoxyhexane.

[0007] By adopting the above technical solution, aluminum hydroxide decomposes endothermically at 200 - 300 °C, releasing crystal water and reducing the surface temperature of the material. The released water forms vapor, diluting the concentrations of oxygen and combustible gases. Melamine cyanurate decomposes at 250 - 400 °C to produce inert gases such as NH3 and HCN, and the cyanuric acid generated by decomposition reacts with the main chain of silicone rubber, promoting the formation of a dense ceramic carbon layer. Under the synergistic system of aluminum hydroxide and melamine cyanurate with the above mass ratio, aluminum hydroxide provides initial endothermic protection, and melamine cyanurate strengthens gas-phase flame retardancy and carbonization at high temperatures, forming a "gas-phase - condensed phase" double barrier, which can improve the limiting oxygen index of silicone rubber. Iron(III) oxide forms a composite oxide with the decomposition product Al2O3 of aluminum hydroxide, improving the thermal stability of the carbon layer. Cerium oxide promotes the secondary cross-linking of silicone rubber at high temperatures, enhancing the strength retention rate after thermal aging. Modified gas-phase nano-silica forms a three-dimensional network in the matrix, which can not only improve the strength but also hinder heat conduction. The decomposition temperature of 2,5-dimethyl-2,5-di-tert-butylperoxyhexane is 170 - 180 °C, which matches the processing temperature of silicone rubber, helping the A component and B component to cross-link fully and improving the strength of silicone rubber. Therefore, this application can improve the flame retardancy, high-temperature resistance, and high-strength performance of silicone rubber simultaneously, contributing to the expansion of the application scenarios of silicone rubber.

[0008] In a specific feasible embodiment, the base rubber is raw rubber with a vinyl molar content of 0.12 - 0.20%.

[0009] By adopting the above technical solution, vinyl is the key active site for the vulcanization reaction of silicone rubber, and its content directly affects the structure and density of the cross-linking network. Through experiments, it is found in this application that raw rubber with a vinyl molar content of 0.12 - 0.20% can ensure sufficient cross-linking points, avoid low mechanical strength and poor heat resistance caused by insufficient vulcanization, and prevent embrittlement caused by too high cross-linking density, maintaining the elasticity and tear resistance of the material. Moreover, the vinyl raw rubber and modified gas-phase SiO2 are combined through hydrogen bonds and chemical bonds to form a "polymer - filler" interpenetrating network. By using the above base rubber, the high-temperature resistance and strength of silicone rubber can be further improved.

[0010] In a specific feasible embodiment, the flame retardant further includes silicone resin micropowder and ammonium polyphosphate, and the mass ratio of aluminum hydroxide, silicone resin micropowder, and ammonium polyphosphate is 10:(3 - 5):(1 - 3).

[0011] By adopting the above technical solution, aluminum hydroxide decomposes endothermically at 200 - 300 °C. Ammonium polyphosphate decomposes at 250 - 350 °C to form polyphosphoric acid, which catalyzes the dehydration of silicone resin and base rubber into carbon, promoting the formation of a dense and expanded carbon layer. Silicone resin micropowder pyrolyzes at 400 - 600 °C to form a ceramic layer, isolating heat and oxygen and blocking the release of combustible gases. A continuous flame retardant protective layer is formed with aluminum hydroxide absorbing heat at low temperature, ammonium polyphosphate forming carbon at medium temperature, and silicone resin micropowder and melamine cyanurate undergoing high-temperature ceramization. The four components synergistically can greatly improve the flame retardancy and high-temperature resistance of silicone rubber.

[0012] In a specific feasible embodiment, the flame retardant further includes zinc borate.

[0013] By adopting the above technical solution, zinc borate decomposes at 300 - 450 °C to form B2O3, and B2O3 reacts with the decomposition products of melamine cyanurate to form a borosilicate glass network, enhancing the density of the carbon layer. This can not only improve the flame retardant effect but also inhibit the generation of dripping.

[0014] In a specific feasible embodiment, the B component further includes bis(2,5 - dimethyl - 2,5 - bis(tert - butylperoxy)hexane), triallyl isocyanurate, and tetramethyldivinyldisiloxane.

[0015] By adopting the above technical solution, during the vulcanization of silicone rubber, bis(2,5 - dimethyl - 2,5 - bis(tert - butylperoxy)hexane) generates side chains with vinyl groups of silicone rubber to form a uniform three - dimensional cross - linked network. The three allyl groups of triallyl isocyanurate serve as active sites and combine with the free radicals of bis(2,5 - peroxide) to form multi - branched cross - linked points, enhancing the cross - linked network density. Tetramethyldivinyldisiloxane reduces the viscosity of the mixed rubber, improves the filler dispersion, and its vinyl functional groups participate in cross - linking, introducing flexible chain segments to balance the rigidity and elasticity of the material.

[0016] In a specific feasible embodiment, the A component further includes silicon carbide whiskers.

[0017] By adopting the above technical solution, the thermal conductivity of silicon carbide whiskers is much higher than that of silicone rubber, which can accelerate heat diffusion and reduce the thermal degradation rate. Silicon carbide whiskers combine with the decomposition products of the flame retardant to form a composite carbon layer, blocking oxygen and heat.

[0018] In a specific feasible embodiment, the A component further includes a hindered phenol antioxidant.

[0019] By adopting the above technical solution, the hindered phenol antioxidant can exert an antioxidant effect for a long time, inhibit the catalytic oxidation of the acidic substances generated by the decomposition of the flame retardant to the main chain of silicone rubber, and maintain the stability of the flame retardant layer.

[0020] Second aspect, a preparation method of a flame-retardant, high-temperature resistant and high-strength silicone rubber provided by the present application adopts the following technical solutions: A preparation method of a flame-retardant, high-temperature resistant and high-strength silicone rubber includes the following steps: S1. Add the base rubber into a mixer, and sequentially add modified fumed nano-silica, a flame retardant, cerium oxide and iron oxide. After each addition, mix for 1 - 10 min. After mixing and forming, discharge the rubber, filter it, and cool it to room temperature to obtain Component A; S2. Add Component B to Component A, mix evenly, and perform mold pressing and vulcanization at a vulcanization temperature of 172 - 180 °C and a vulcanization pressure of 8.5 - 10.5 MPa for 4 - 6 min. Then transfer it to an environment of 195 - 205 °C for secondary vulcanization. After heat preservation for 3.8 - 4.2 h, naturally cool it to room temperature to obtain the flame-retardant, high-temperature resistant and high-strength silicone rubber.

[0021] By adopting the above technical solutions, each filler is added in sequence and mixed for a period of time after each addition, which helps the fillers to be evenly dispersed. Moreover, adding the modified fumed nano-silica first helps the modified fumed nano-silica to occupy the gaps between the base rubber molecular chains and form a three-dimensional network. Then add the flame retardant to avoid being wrapped by SiO2 and ensure the uniform distribution of the decomposition products. Finally, add cerium oxide and iron oxide to reduce the side reaction with the flame retardant at high temperature. After discharging the rubber, filter and cool it to remove the undispersed filler clusters, reduce the stress concentration points and improve the strength. In step S2, the two-stage vulcanization with the above temperature and time helps to improve the uniformity of the crosslinking density, ensure the density of the product and eliminate the internal stress.

[0022] 1. By adopting specific raw material ratios and preparation methods, the present application can improve the flame retardancy, high-temperature resistance and high-strength properties of the silicone rubber simultaneously.

[0023] 2. In the present application, it is preferably to use raw rubber with a vinyl molar content of 0.12 - 0.20%, which can further improve the high-temperature resistance and strength of the silicone rubber.

[0024] 3. The method of the present application can remove the undispersed filler clusters, improve the uniformity of the crosslinking density, reduce the stress concentration points and improve the strength. Specific Embodiments

[0025] The following further elaborates the present application with reference to examples and comparative examples. Among them, the raw rubber is methyl vinyl raw rubber.

[0026] Examples

[0027] Example 1: This example provides a flame-retardant, high-temperature resistant, and high-strength silicone rubber, which includes component A and component B. Among them, component A includes the following raw materials: 100 g of raw rubber with a vinyl molar content of 0.16%, 25 g of modified fumed nano-silica (model CAB-O-SIL TS620), 3 g of cerium oxide, 2 g of ferric oxide, 10 g of flame retardant, and the flame retardant includes aluminum hydroxide and melamine cyanurate with a mass ratio of 10:3.

[0028] Component B is 2,5-dimethyl-2,5-di-tert-butylperoxyhexane.

[0029] This example also provides a preparation method for the flame-retardant, high-temperature resistant, and high-strength silicone rubber, which includes the following steps: Add the raw rubber with a vinyl molar content of 0.16% into a mixer, and then, successively add modified fumed nano-silica, flame retardant, cerium oxide, and ferric oxide. After each addition, mix for 3 min. After all are added, mix and shape, extrude the rubber, filter, and cool to room temperature to obtain component A.

[0030] According to the weight ratio of component A: component B = 100:0.7, add component B to component A, mix evenly in an open mill, and then transfer it to a flat vulcanizer for mold pressing vulcanization. The vulcanization temperature is 175 °C, the vulcanization pressure is 10 MPa, and the vulcanization time is 5 min. Then transfer it to an oven at 200 °C for secondary vulcanization. After heat preservation for 4 h, the secondary vulcanization ends, and it is naturally cooled to room temperature to obtain the flame-retardant, high-temperature resistant, and high-strength silicone rubber.

[0031] Example 2: The difference between this example and Example 1 is only that component A includes the following raw materials: 100 g of raw rubber with a vinyl molar content of 0.16%, 20 g of modified fumed nano-silica (model CAB-O-SIL TS620), 5 g of cerium oxide, 3 g of ferric oxide, and 15 g of flame retardant.

[0032] Example 3: The difference between this example and Example 1 is only that component A includes the following raw materials: 100 g of raw rubber with a vinyl molar content of 0.16%, 30 g of modified fumed nano-silica (model CAB-O-SIL TS620), 1 g of cerium oxide, 1 g of ferric oxide, and 5 g of flame retardant.

[0033] Example 4: The difference between this example and Example 1 is only that the flame retardant includes aluminum hydroxide and melamine cyanurate with a mass ratio of 5:1.

[0034] Example 5: The difference between this example and Example 1 is only that the flame retardant includes aluminum hydroxide and melamine cyanurate with a mass ratio of 5:2.

[0035] Example 6: The difference between this example and Example 1 lies only in the preparation method of the flame-retardant, high-temperature resistant, and high-strength silicone rubber, which includes the following steps: Add the raw rubber with a vinyl molar content of 0.16% into a kneader, and then, successively add modified fumed nano-silica, flame retardant, cerium oxide, and iron oxide. After each addition, knead for 1 min. After all are added, knead and form, extrude the rubber, filter, and cool to room temperature to obtain Component A.

[0036] According to the weight ratio of Component A:Component B = 100:0.7, add Component B to Component A, mix evenly in an open mill, and then transfer to a flat vulcanizer for compression molding. The vulcanization temperature is 172 °C, the vulcanization pressure is 10.5 MPa, and the vulcanization time is 6 min. Then transfer to an oven at 195 °C for secondary vulcanization. After heat preservation for 4.2 h, the secondary vulcanization is completed, and it is naturally cooled to room temperature to obtain the flame-retardant, high-temperature resistant, and high-strength silicone rubber.

[0037] Example 7: The difference between this example and Example 1 lies only in the preparation method of the flame-retardant, high-temperature resistant, and high-strength silicone rubber, which includes the following steps: Add the raw rubber with a vinyl molar content of 0.16% into a kneader, and then, successively add modified fumed nano-silica, flame retardant, cerium oxide, and iron oxide. After each addition, knead for 10 min. After all are added, knead and form, extrude the rubber, filter, and cool to room temperature to obtain Component A.

[0038] According to the weight ratio of Component A:Component B = 100:0.7, add Component B to Component A, mix evenly in an open mill, and then transfer to a flat vulcanizer for compression molding. The vulcanization temperature is 180 °C, the vulcanization pressure is 8.5 MPa, and the vulcanization time is 4 min. Then transfer to an oven at 205 °C for secondary vulcanization. After heat preservation for 3.8 h, the secondary vulcanization is completed, and it is naturally cooled to room temperature to obtain the flame-retardant, high-temperature resistant, and high-strength silicone rubber.

[0039] Example 8: The difference between this example and Example 1 lies only in that the raw rubber with a vinyl molar content of 0.16% is replaced with an equal amount of raw rubber with a vinyl molar content of 0.10%.

[0040] Example 9: The difference between this example and Example 1 lies only in that the raw rubber with a vinyl molar content of 0.16% is replaced with an equal amount of raw rubber with a vinyl molar content of 0.12%.

[0041] Example 10: The difference between this example and Example 1 lies only in that the raw rubber with a vinyl molar content of 0.16% is replaced with an equal amount of raw rubber with a vinyl molar content of 0.20%.

[0042] Example 11: The difference between this example and Example 1 is only that the raw rubber with a vinyl molar content of 0.22% is used to replace the raw rubber with a vinyl molar content of 0.16% in equal amounts.

[0043] Example 12: The difference between this example and Example 1 is only that the flame retardant includes aluminum hydroxide, melamine cyanurate, silicone resin micropowder (model ZHPUZPF-1009), and ammonium polyphosphate with a mass ratio of 10:3:4:2.

[0044] Example 13: The difference between this example and Example 1 is only that the flame retardant includes aluminum hydroxide, melamine cyanurate, silicone resin micropowder (model ZHPUZPF-1009), and ammonium polyphosphate with a mass ratio of 10:3:3:1.

[0045] Example 14: The difference between this example and Example 1 is only that the flame retardant includes aluminum hydroxide, melamine cyanurate, silicone resin micropowder (model ZHPUZPF-1009), and ammonium polyphosphate with a mass ratio of 10:3:5:3.

[0046] Example 15: The difference between this example and Example 1 is only that the flame retardant includes aluminum hydroxide, melamine cyanurate, and zinc borate with a mass ratio of 10:3:1.

[0047] Example 16: The difference between this example and Example 1 is only that the flame retardant includes aluminum hydroxide, melamine cyanurate, silicone resin micropowder (model ZHPUZPF-1009), ammonium polyphosphate, and zinc borate with a mass ratio of 10:3:4:2:1.

[0048] Example 17: The difference between this example and Example 1 is only that the B component includes 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, bis(2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), triallyl isocyanurate, and tetramethyldivinyldisiloxane with a mass ratio of 10:3:3:3. In the preparation method of the flame-retardant, high-temperature-resistant, and high-strength silicone rubber: Mix 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, bis(2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), triallyl isocyanurate, and tetramethyldivinyldisiloxane according to the ratio to obtain the B component. According to the weight ratio of A component:B component = 100:0.7, add the B component to the A component, mix evenly in an open mill, then transfer it to a flat vulcanizer for compression molding and vulcanization. The vulcanization temperature is 175°C, the vulcanization pressure is 10 MPa, the vulcanization time is 5 min, then transfer it to an oven at 200°C for secondary vulcanization. After heat preservation for 4 h, the secondary vulcanization is completed, and it is naturally cooled to room temperature to obtain the flame-retardant, high-temperature-resistant, and high-strength silicone rubber.

[0049] Example 18: The only difference between this example and Example 1 is that the A component includes the following raw materials: 100 g of raw rubber with a vinyl molar content of 0.16%, 25 g of modified fumed nano-silica (model CAB-O-SIL TS620), 3 g of cerium oxide, 2 g of ferric oxide, 10 g of flame retardant, and 1 g of silicon carbide whiskers. In the preparation method of flame-retardant, high-temperature resistant, and high-strength silicone rubber: Add the raw rubber with a vinyl molar content of 0.16% to a mixer, and then, successively add modified fumed nano-silica, silicon carbide whiskers, flame retardant, cerium oxide, and ferric oxide. After each addition, mix for 3 min. After all are added, mix and form, extrude the rubber, filter, and cool to room temperature to obtain the A component.

[0050] Example 19: The only difference between this example and Example 1 is that the A component includes the following raw materials: 100 g of raw rubber with a vinyl molar content of 0.16%, 25 g of modified fumed nano-silica (model CAB-O-SIL TS620), 3 g of cerium oxide, 2 g of ferric oxide, 10 g of flame retardant, and 1 g of hindered phenol antioxidant (antioxidant 3114). In the preparation method of flame-retardant, high-temperature resistant, and high-strength silicone rubber: Add the raw rubber with a vinyl molar content of 0.16% to a mixer, and then, successively add modified fumed nano-silica, hindered phenol antioxidant, flame retardant, cerium oxide, and ferric oxide. After each addition, mix for 3 min. After all are added, mix and form, extrude the rubber, filter, and cool to room temperature to obtain the A component.

[0051] Example 20: The only difference between this example and Example 1 is that the A component includes the following raw materials: 100 g of raw rubber with a vinyl molar content of 0.16%, 25 g of modified fumed nano-silica (model CAB-O-SIL TS620), 3 g of cerium oxide, 2 g of ferric oxide, 10 g of flame retardant, 1 g of silicon carbide whiskers (brand XBY-SIC), 1 g of hindered phenol antioxidant (antioxidant 3114), and the flame retardant includes aluminum hydroxide and melamine cyanurate with a mass ratio of 10:3.

[0052] The B component includes 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, bis(2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), triallyl isocyanurate, and tetramethyldivinyldisiloxane with a mass ratio of 10:3:3:3.

[0053] This example also provides a preparation method of flame-retardant, high-temperature resistant, and high-strength silicone rubber, including the following steps: Add the raw rubber with a vinyl molar content of 0.16% into a kneader. Then, sequentially add modified fumed nano-silica, silicon carbide whiskers, hindered phenol antioxidant, flame retardant, cerium oxide and iron(III) oxide. After each addition, knead for 3 min. After all the ingredients are added, knead and form, extrude the rubber, filter, and cool to room temperature to obtain Component A.

[0054] According to the ratio, mix 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, bis(2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane), triallyl isocyanurate and tetramethyldivinyldisiloxane to obtain Component B. According to the weight ratio of Component A:Component B = 100:0.7, add Component B to Component A, mix evenly in an open mill, and then transfer to a flat vulcanizer for compression vulcanization. The vulcanization temperature is 175 °C, the vulcanization pressure is 10 MPa for compression vulcanization, the vulcanization time is 5 min, and then transfer to an oven at 200 °C for secondary vulcanization. After heat preservation for 4 h, the secondary vulcanization is completed, and it is naturally cooled to room temperature to obtain a flame-retardant, high-temperature resistant and high-strength silicone rubber.

[0055] Comparative Example Comparative Example 1 The difference between this comparative example and Example 1 is only that Component A includes the following raw materials: 100 g of raw rubber with a vinyl molar content of 0.16%, 25 g of modified fumed nano-silica (model CAB-O-SIL TS620), 3 g of cerium oxide, 2 g of iron(III) oxide, and 10 g of aluminum hydroxide.

[0056] Comparative Example 2 The difference between this comparative example and Example 1 is only that Component A includes the following raw materials: 100 g of raw rubber with a vinyl molar content of 0.16%, 25 g of modified fumed nano-silica (model CAB-O-SIL TS620), 3 g of cerium oxide, 2 g of iron(III) oxide, and 10 g of melamine cyanurate.

[0057] Comparative Example 3 The difference between this comparative example and Example 1 is only that Component A includes the following raw materials: 125 g of raw rubber with a vinyl molar content of 0.16%, 3 g of cerium oxide, 2 g of iron(III) oxide, 10 g of flame retardant, and the flame retardant includes aluminum hydroxide and melamine cyanurate with a mass ratio of 10:3.

[0058] Comparative Example 4 The difference between this comparative example and Example 1 is only that Component A includes the following raw materials: 103 g of raw rubber with a vinyl molar content of 0.16%, 25 g of modified fumed nano-silica (model CAB-O-SIL TS620), 2 g of iron(III) oxide, 10 g of flame retardant, and the flame retardant includes aluminum hydroxide and melamine cyanurate with a mass ratio of 10:3.

[0059] Comparative Example 5 The difference between this comparative example and Example 1 is only that the A component includes the following raw materials: 102 g of raw rubber with a vinyl molar content of 0.16%, 25 g of modified fumed nano-silica (model CAB-O-SIL TS620), 3 g of cerium oxide, 10 g of flame retardant, and the flame retardant includes aluminum hydroxide and melamine cyanurate with a mass ratio of 10:3.

[0060] Performance detection test For Examples 1-20 and Comparative Examples 1-5, the following performance detections were carried out: According to the UL94 standard, the flame retardant grade of the silicone rubber was detected.

[0061] According to DIN53505, the hardness (Shore A), tensile strength, and elongation at break of the silicone rubber prepared in each example and comparative example were detected.

[0062] High-temperature resistance test: The silicone rubber prepared in each example and comparative example was respectively placed in an oven at 300 °C. After aging at a constant temperature for 72 h and 168 h, the hardness (Shore A), tensile strength, and elongation at break of the silicone rubber were detected.

[0063] The results are shown in Tables 1-3.

[0064] Table 1

[0065] Table 2

[0066] Table 3

[0067] Combining Example 1 and Comparative Examples 1-5 and combining Tables 1-3, it can be seen that compared with Example 1, the flame retardant grade of Comparative Examples 1-5 becomes lower, and at least one of the hardness, elongation at break, and tensile strength becomes significantly worse. Moreover, after aging at 300 °C for 72 h and 168 h, the hardness, elongation at break, and tensile strength all become significantly worse. This shows that adopting the raw material ratio and preparation method of Example 1 helps to improve the flame retardancy, high-temperature resistance, and high-strength performance of the silicone rubber simultaneously.

[0068] Combining Examples 1-20 and combining Table 1, it can be seen that the flame retardant grades of Examples 1-20 are all above V1 level, and moreover, the hardness, elongation at break, and tensile strength are all relatively large. After aging at 300 °C for 72 h and 168 h, the changes in hardness, elongation at break, and tensile strength are relatively small. This shows that adopting the raw material ratio and preparation method of Example 1 helps to improve the flame retardancy, high-temperature resistance, and high-strength performance of the silicone rubber simultaneously.

[0069] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment that do not contribute creatively as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A flame-retardant, high-temperature resistant and high-strength silicone rubber, characterized in that, It includes Component A and Component B. Component A includes raw materials in the following parts by weight: 100 parts of base rubber, 20 - 30 parts of modified fumed nano-silica, 1 - 5 parts of cerium oxide, 1 - 3 parts of ferric oxide, 5 - 15 parts of flame retardant, and 1 part of silicon carbide whisker. The flame retardant includes aluminum hydroxide, melamine cyanurate, silicone resin micropowder, and ammonium polyphosphate with a mass ratio of 10:(2 - 4):(3 - 5):(1 - 3); Component B includes 2,5 - dimethyl - 2,5 - di - tert - butylperoxyhexane, bis(2,5 - dimethyl - 2,5 - bis(tert - butylperoxy)hexane), triallyl isocyanurate, and tetramethyldivinyldisiloxane with a mass ratio of 10:3:3:

3.

2. The flame-retardant, high-temperature resistant and high-strength silicone rubber according to claim 1, wherein, The base rubber is raw rubber with a vinyl molar content of 0.12 - 0.20%.

3. The flame-retardant, high-temperature resistant and high-strength silicone rubber according to claim 1, wherein The flame retardant also includes zinc borate.

4. The flame-retardant, high-temperature resistant and high-strength silicone rubber according to claim 1, wherein, Component A also includes a hindered phenol antioxidant.

5. A preparation method of a flame-retardant, high-temperature resistant and high-strength silicone rubber, applicable to the flame-retardant, high-temperature resistant and high-strength silicone rubber described in any one of claims 1-4, characterized in that, It includes the following steps: S1. Add the base rubber into a mixer, and successively add modified fumed nano - silica, flame retardant, cerium oxide, and ferric oxide. After each addition, mix for 1 - 10 min. After mixing and forming, take out the rubber, filter, and cool to room temperature to obtain Component A. S2. Add Component B to Component A and mix evenly. Perform mold pressing vulcanization at a vulcanization temperature of 172 - 180 °C and a vulcanization pressure of 8.5 - 10.5 MPa for 4 - 6 min, then transfer to an environment of 195 - 205 °C for secondary vulcanization. After heat preservation for 3.8 - 4.2 h, cool naturally to room temperature to obtain a flame - retardant, high - temperature - resistant, and high - strength silicone rubber.

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