Silicone rubber material for nuclear power plant sealing and preparation method thereof

Abstract

The invention discloses a silicone rubber material for nuclear power plant sealing and a preparation method thereof, and belongs to the technical field of nuclear power plant sealing, and the silicone rubber material is prepared from the following raw materials in parts by weight: 100 parts of methyl phenyl silicone rubber raw rubber, 50-60 parts of modified fumed silica, 5-15 parts of phenyl silicone resin microspheres, 3-8 parts of silane coupling agent treated nano boron nitride and 1.5-2.5 parts of bis-2, 5 vulcanizing agent. 0.5 to 1.2 parts of vinyl trimethoxy silane, 2 to 5 parts of hydroxyl fluorosilicone oil and 1 to 3 parts of nano cerium oxide; wherein the phenyl content of the phenyl silicone resin microspheres is 40-60 mol%, the particle size is 5-15 [mu] m, and the wall thickness is 1-3 [mu] m; the particle size of the nano boron nitride is 20-50nm, and the nano boron nitride is subjected to gamma-aminopropyltriethoxysilane surface treatment. According to the silicone rubber material disclosed by the invention, the radiation-resistant dose is increased to 2.5 MGy, and the tritium permeability coefficient is reduced by 78%; the compression permanent deformation rate at 250 DEG C is less than or equal to 18%; and the tensile strength retention rate after irradiation is greater than or equal to 85%.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power plant sealing, in particular to a silicone rubber material for nuclear power plant sealing and a preparation method thereof. Background Art

[0002] Methylphenyl silicone rubber is widely used in nuclear power plant seals due to its high and low temperature resistance (-60 to 250°C) and radiation resistance. However, existing technologies have the following drawbacks: Main chain breakage is prone to occur under high-dose radiation (>1MGy), leading to seal failure; compression set increases in long-term high-temperature environments, affecting seal reliability; and the barrier capability against small radioactive molecules such as tritium is insufficient.

[0003] Existing radiation-resistant silicone rubbers utilize silica / silicon carbide composite fillers, but this fails to address the volume expansion caused by irradiation gassing. Existing technologies enhance heat resistance by adding cerium oxide, but this fails to create a dynamic repair network. Therefore, there is an urgent need to develop silicone rubber materials that combine radiation resistance, permeation resistance, and self-healing properties. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a silicone rubber material for nuclear power plant sealing and a preparation method thereof, so as to solve the problems raised in the background technology. In view of the problems existing in the existing silicone rubber materials in nuclear power plant sealing applications, such as insufficient radiation resistance, large high-temperature compression deformation, and high permeability of radioactive substances, a special silicone rubber material with optimized comprehensive performance and a preparation method are provided.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] In one aspect, the present invention discloses a silicone rubber material for sealing a nuclear power plant. The silicone rubber material comprises the following raw materials in parts by weight:

[0007] 100 parts of methylphenyl silicone rubber;

[0008] 50-60 parts of modified fumed silica;

[0009] 5-15 parts of phenyl silicone resin microspheres;

[0010] 3-8 parts of nano-boron nitride treated with silane coupling agent;

[0011] 1.5-2.5 parts of double 2,5 curing agent;

[0012] 0.5-1.2 parts of vinyltrimethoxysilane;

[0013] 2-5 parts of hydroxyfluorosilicone oil;

[0014] 1-3 parts of nano-cerium oxide;

[0015] The phenyl content of the phenyl silicone resin microspheres is 40-60 mol%, the particle size is 5-15 μm, and the wall thickness is 1-3 μm; the particle size of the nano boron nitride is 20-50 nm, and the nano boron nitride is surface treated by γ-aminopropyl triethoxysilane.

[0016] In some embodiments of the present application, the methyl phenyl silicone rubber raw rubber has a phenyl content of 18-25 mol%, a vinyl content of 0.8-1.2 mol%, and a molecular weight of 800-1000.

[0017] In some embodiments of the present application, the modified fumed white carbon black is fumed silica that is hydrophobically treated by hexamethyldisilazane, has a specific surface area of 200-300 m 2 / g, and the amount of the hydrophobic treatment agent is 3-5% of the weight of the fumed silica.

[0018] In some embodiments of the present application, the amount of the nano boron nitride is 4-6 parts, and the mass ratio of γ-aminopropyl triethoxysilane to the nano boron nitride in the silane coupling agent treatment process is 1:10-1:15.

[0019] In some embodiments of the present application, the hydroxyl fluorosilicone oil has a fluorine content of 10±0.5%, a viscosity of 800±50 mPa·s, and a weight ratio to the nano cerium oxide of 3:1-5:1.

[0020] Another aspect of the present application discloses a preparation method of the above-mentioned silicone rubber material, which comprises the following steps:

[0021] (1) Dynamic pre-crosslinking: mixing the methyl phenyl silicone rubber raw rubber and the hydroxyl fluorosilicone oil in a mixer at 80-100℃ and a rotation speed of 25-35 rpm for 15-20 minutes;

[0022] (2) Gradient filler dispersion: adding the modified fumed white carbon black and the nano boron nitride in two stages, the first stage is mixing at 110-120℃ for 20 minutes, and the second stage is mixing at 60℃ under a vacuum degree of -0.08 to -0.1 MPa for 30 minutes;

[0023] (3) Functional additive compounding: adding the phenyl silicone resin microspheres in three times with an interval of 5 min, the mixing temperature is less than or equal to 70℃, and the total time is 40 minutes;

[0024] (4) Vulcanization forming: the first stage vulcanization adopts a temperature of 170℃, pressure vulcanization for 15 min, the pressure is 8-10 MPa, the second stage vulcanization adopts a stepwise temperature rising program, pressure vulcanization at 120℃ for 1 h, then pressure vulcanization at 150℃ for 1 h, and finally pressure vulcanization at 200℃ for 4 h.

[0025] In some embodiments of the present application, in step (2), nano-boron nitride is added in two times, 50-60% of the total amount is added in the first time, and the remaining amount is added in the second time, and nano-cerium oxide is added simultaneously with the second time.

[0026] The above technical solution has the following beneficial effects:

[0027] A silicone rubber material for nuclear power plant sealing prepared using the technical solution of the present application has an irradiation dose resistance increased to 2.5MGy, a tritium permeability coefficient reduced by 78%, a compression permanent deformation rate of less than or equal to 18% at 250°C, and a tensile strength retention rate after irradiation of greater than or equal to 85%. DETAILED DESCRIPTION

[0028] The following is a further description of specific embodiments of the present invention. It should be noted that the description of these embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0029] Example 1

[0030] A silicone rubber material for nuclear power plant sealing, comprising the following raw materials in parts by weight: 100 parts of methylphenyl silicone rubber; 50-60 parts of modified fumed silica; 5-15 parts of phenyl silicone resin microspheres; 3-8 parts of nano-boron nitride treated with a silane coupling agent; 1.5-2.5 parts of a bis-2,5 vulcanizing agent; 0.5-1.2 parts of vinyltrimethoxysilane; 2-5 parts of hydroxyfluorosilicone oil; and 1-3 parts of nano-cerium oxide.

[0031] Specifically, the raw materials of the silicone rubber material for nuclear power plant sealing include, by weight: 100 parts of methyl phenyl silicone rubber; 50 or 60 parts of modified fumed silica; 5 or 15 parts of phenyl silicone resin microspheres; 3 or 8 parts of nano-boron nitride treated with a silane coupling agent; 1.5 or 2.5 parts of a double 2,5 vulcanizing agent; 0.5 or 1.2 parts of vinyl trimethoxysilane; 2 or 5 parts of hydroxy fluorosilicone oil; and 1 or 3 parts of nano-cerium oxide.

[0032] The phenyl content of the phenyl silicone resin microspheres is 40-60 mol%, the particle size is 5-15 μm, and the wall thickness is 1-3 μm; the particle size of the nano boron nitride is 20-50 nm, and the surface is treated with γ-aminopropyltriethoxysilane;

[0033] Specifically, the phenyl content of the phenyl silicone resin microspheres can be 40 mol% or 60 mol%, the particle size can be 5 μm or 15 μm, and the wall thickness can be 1 μm or 3 μm; the particle size of the nano-boron nitride can be 20 nm or 50 nm, and the nano-boron nitride is surface treated with γ-aminopropyltriethoxysilane.

[0034] In some embodiments of the present application, the methylphenyl silicone rubber has a phenyl content of 18 to 25 mol%, a vinyl content of 0.8 to 1.2 mol%, and a molecular weight of 800,000 to 1,000,000;

[0035] Specifically, the methylphenyl silicone rubber raw rubber may have a phenyl content of 18 mol% or 25 mol%, a vinyl content of 0.8 mol% or 1.2 mol%, and a molecular weight of 800,000 or 1,000,000.

[0036] In some embodiments of the present application, the modified fumed silica is fumed silica treated with hexamethyldisilazane for hydrophobicity, and has a specific surface area of ​​200 to 300 m 2 / g, the amount of hydrophobic treatment agent is 3-5% of the weight of white carbon black.

[0037] Specifically, the modified fumed silica can be fumed silica treated with hexamethyldisilazane for hydrophobicity, and the specific surface area can be 200 m 2 / g or 300m 2 / g, and the amount of hydrophobic treatment agent is 3% or 5% of the weight of white carbon black.

[0038] In some embodiments of the present application, the amount of nano-boron nitride used is 4 to 6 parts, and the mass ratio of γ-aminopropyltriethoxysilane to nano-boron nitride during the silane coupling agent treatment is 1:10 to 1:15.

[0039] Specifically, the amount of nano-boron nitride used is 4 parts or 6 parts, and the mass ratio of γ-aminopropyltriethoxysilane to nano-boron nitride during the silane coupling agent treatment is 1:10 or 1:15.

[0040] In some embodiments of the present application, the fluorine content of the hydroxyl fluorosilicone oil is 10±0.5%, the viscosity is 800±50 mPa·s, and the weight ratio of the hydroxyl fluorosilicone oil to the nano-cerium oxide is 3:1 to 5:1.

[0041] Specifically, the fluorine content of the hydroxyl fluorosilicone oil is 9.5% or 10.5%, the viscosity can be 750 mPa·s or 850 mPa·s, and the weight ratio of the hydroxyl fluorosilicone oil to the nano-cerium oxide is 3:1 or 5:1.

[0042] Example 2

[0043] A silicone rubber material for nuclear power plant sealing comprises the following raw materials in parts by weight: 100 parts of methylphenyl silicone rubber; 50 parts or 60 parts of modified fumed silica; 10 parts of phenyl silicone resin microspheres; 5 parts of nano-boron nitride; 1.5 parts or 2.5 parts of double 2,5 vulcanizing agent; 0.5 parts or 1.2 parts of vinyltrimethoxysilane; 3 parts of hydroxyfluorosilicone oil; and 2 parts of nano-cerium oxide.

[0044] Example 3

[0045] A silicon rubber material for sealing a nuclear power plant, comprising the following raw materials by weight: methyl phenyl silicone rubber gum 100 parts; modified fumed white carbon black 50 parts or 60 parts; phenyl silicone resin microspheres 8 parts; nano boron nitride 6 parts; bis 2,5 curing agent 1.5 parts or 2.5 parts; vinyl trimethoxysilane 0.5 parts or 1.2 parts; hydroxyl fluorosilicone oil 3 parts; nano cerium oxide 2 parts.

[0046] Example 4

[0047] A silicon rubber material for sealing a nuclear power plant, comprising the following raw materials by weight: methyl phenyl silicone rubber gum 100 parts; modified fumed white carbon black 50 parts or 60 parts; phenyl silicone resin microspheres 12 parts; nano boron nitride 4 parts; bis 2,5 curing agent 1.5 parts or 2.5 parts; vinyl trimethoxysilane 0.5 parts or 1.2 parts; hydroxyl fluorosilicone oil 4 parts; nano cerium oxide 3 parts.

[0048] Example 5

[0049] A silicon rubber material for sealing a nuclear power plant, comprising the following raw materials by weight: methyl phenyl silicone rubber gum 100 parts; modified fumed white carbon black 50 parts or 60 parts; phenyl silicone resin microspheres 5 parts; nano boron nitride 8 parts; bis 2,5 curing agent 1.5 parts or 2.5 parts; vinyl trimethoxysilane 0.5 parts or 1.2 parts; hydroxyl fluorosilicone oil 2 parts; nano cerium oxide 1 part.

[0050] Example 6

[0051] A silicon rubber material for sealing a nuclear power plant, comprising the following raw materials by weight: methyl phenyl silicone rubber gum 100 parts; modified fumed white carbon black 50 parts or 60 parts; phenyl silicone resin microspheres 15 parts; nano boron nitride 3 parts; bis 2,5 curing agent 1.5 parts or 2.5 parts; vinyl trimethoxysilane 0.5 parts or 1.2 parts; hydroxyl fluorosilicone oil 3 parts; nano cerium oxide 3 parts.

[0052] Example 7

[0053] A silicon rubber material for sealing a nuclear power plant, comprising the following raw materials by weight: methyl phenyl silicone rubber gum 100 parts; modified fumed white carbon black 50 parts or 60 parts; phenyl silicone resin microspheres 10 parts, wherein the phenyl content of the phenyl silicone resin microspheres is 60 mol%; nano boron nitride treated with silane coupling agent 5 parts, the mass ratio of γ-aminopropyl triethoxysilane to nano boron nitride during the silane coupling agent treatment process is 1:12; bis 2,5 curing agent 1.5 parts or 2.5 parts; vinyl trimethoxysilane 0.5 parts or 1.2 parts, hydroxyl fluorosilicone oil 3 parts; nano cerium oxide 2 parts.

[0054] Comparative Example

[0055] A silicone rubber material comprising the following raw materials by weight: methyl phenyl silicone rubber gum 100 parts; modified fumed white carbon black 50 parts or 60 parts; bis 2,5 vulcanizing agent 1.5 parts or 2.5 parts; vinyl trimethoxysilane 0.5 parts or 1.2 parts; the comparative example is a prior art traditional formula, no phenyl silicone resin microspheres, nano boron nitride, hydroxyl fluorosilicone oil and nano cerium oxide are added in the formula of the comparative example.

[0056] The amount of phenyl silicone resin microspheres, nano boron nitride, hydroxyl fluorosilicone oil and nano cerium oxide added in examples 2-7 and the comparative example is shown in Table 1 below.

[0057] Table 1:

[0058] Example Phenyl silicone resin microspheres (parts) Nano boron nitride (parts) Hydroxyfluorosilicone oil (parts) Nano cerium oxide (parts) 2 10 5 3 2 3 8 6 3 2 4 12 4 4 3 5 5 8 2 1 6 15 3 5 3 7 10 (phenyl group 60 mol%) 5 (Silane treated) 3 2 Comparative Example 0 0 0 0

[0059] The performance test results of the above examples 2-7 and the comparative example are shown in Table 2 below.

[0060] Table 2:

[0061]

[0062]

[0063] Among them, the radiation resistance dose refers to ASTM D750, using a cobalt-60 radiation source, the dose rate is 1 kGy / h; the tritium permeation coefficient is tested by the gas permeation cell method according to ISO 2782 standard; the compression permanent set is measured after compression of 25% at 200°C for 24h according to GB / T 7759; the heat aging performance is tested after the sample is placed in an oven at 250°C for 168h.

[0064] From Table 2, it can be seen that:

[0065] Phenyl silicone resin microsphere content effect: the radiation resistance performance of example 6 (15 parts of phenyl silicone resin microspheres) is the best (2.7 MGy), but the tritium permeation coefficient of example 5 (5 parts of phenyl silicone resin microspheres) increases to 1.2 x 10 -14 m 2 / s, indicating that the content of phenyl silicone resin microspheres needs to be greater than or equal to 8 parts to effectively block permeation;

[0066] Fluorosilicone oil synergistic effect: the compression permanent set rate of example 4 (4 parts of hydroxyl fluorosilicone oil) (15%) is better than that of example 3 (20%), indicating that the increase of fluorine content can improve the dynamic repair ability;

[0067] Boron nitride treatment optimization: example 7 uses silane treated and optimized boron nitride, and the elongation retention rate after heat aging is as high as 92%, which is increased by 7% compared with example 2.

[0068] Example 8

[0069] A method for preparing the above-mentioned silicone rubber material, the preparation method comprising the following steps:

[0070] Step 1: Dynamic pre-crosslinking: Mix the methylphenyl silicone rubber and hydroxyl fluorosilicone oil in an internal mixer at 80-100°C and 25-35 rpm for 15-20 minutes;

[0071] Step 2: Gradient filler dispersion: adding modified fumed silica and nano-boron nitride in two stages: mixing at 110-120°C for 20 minutes in the first stage and mixing at 60°C and vacuum degree of -0.08-0.1 MPa for 30 minutes in the second stage;

[0072] Step 3: Compounding the functional additives: adding phenyl silicone resin microspheres three times with an interval of 5 minutes, the mixing temperature is less than or equal to 70 ° C, and the total time is 40 minutes;

[0073] Step 4: Vulcanization molding. The first stage vulcanization adopts a temperature of 170℃, pressurized vulcanization for 15 minutes, and a pressure of 8-10MPa. The second stage vulcanization adopts a step-by-step temperature rising program, at a temperature of 120℃, pressurized vulcanization for 1 hour, then at a temperature of 150℃, pressurized vulcanization for 1 hour, and finally at a temperature of 200℃, pressurized vulcanization for 4 hours.

[0074] In some embodiments of the present application, in step 2, nano-boron nitride is added in two times, 50-60% of the total amount is added in the first time, and the remaining part is added in the second time, and nano-cerium oxide is added simultaneously with the second time.

[0075] Specifically, the preparation method of the silicone rubber material includes the following steps:

[0076] Step 1: Dynamic pre-crosslinking

[0077] Operation process:

[0078] 1. Preheat the internal mixer to 80±2℃, add methyl phenyl silicone rubber, and balance it in an environment of 25℃ and humidity <30% for 24 hours;

[0079] 2. Slowly add hydroxy fluorosilicone oil. You can use a metering pump to inject at a speed of 5mL / min, start the mixing rotor, and control the speed to 30±2rpm;

[0080] 3. Continue mixing at 90±5℃ for 15 minutes. During this period, the material is continuously turned over by the scraper on the inner wall of the mixer to ensure that the fluorosilicone oil evenly penetrates into the molecular chains of the raw rubber.

[0081] The principle is: the Si-OH group of hydroxyfluorosilicone oil undergoes a pre-crosslinking reaction with the vinyl group in the raw rubber to form reversible dynamic bonds (hydrogen bonds and coordination bonds); controlling the temperature in the range of 80-100°C promotes molecular chain movement and avoids premature vulcanization.

[0082] Step 2: Gradient filler dispersion

[0083] The first stage (high temperature and high shear dispersion):

[0084] Heat the internal mixer to 115±5°C, set the rotor speed ratio to 1:1.2, promote axial mixing, and set the cooling water flow rate to 20L / min or greater. In the second stage, control the temperature and sequentially add modified fumed silica and 60% nano-boron nitride. The modified fumed silica can be dried in an oven at 120°C for 2 hours in advance. 60% nano-boron nitride is 3 to 4.8 parts of the total addition amount.

[0085] Mix at 45 rpm for 20 minutes to reduce the agglomeration tendency of the filler and to break up the silica aggregates with high shear force.

[0086] The torque value is monitored in real time, and dispersion is determined to be complete when the torque stabilizes at 120-150 N·m.

[0087] The second stage (low temperature vacuum dispersion):

[0088] Cool down to 60±3℃, start the vacuum system, and set the vacuum degree to -0.09±0.01MPa. Equipped with a two-stage vacuum pump consisting of a rotary vane pump and a Roots pump, the ultimate vacuum degree reaches -0.1MPa. Set a pressure sensor for real-time feedback, and the vacuum fluctuation range is less than or equal to ±0.005MPa.

[0089] Add the remaining 40% of nano-boron nitride and nano-cerium oxide, i.e., 2 to 3.2 parts of the remaining 40% of nano-boron nitride, reduce the speed to 20 rpm, and mix for 30 minutes;

[0090] Pause mixing every 5 minutes and use a scraper to clean the material in the dead corners of the mixing chamber to ensure that there is no filler deposition.

[0091] In the high-temperature stage, high-specific-surface-area silica is dispersed first to avoid uneven dispersion due to increased viscosity at low temperatures; adsorbed gases are removed in a vacuum environment to prevent secondary agglomeration of nanoparticles; and the gradual addition of boron nitride can reduce filler-filler interactions and improve the efficiency of thermal network construction.

[0092] Step 3: Compounding of functional additives

[0093] Phenyl silicone resin microspheres introduction:

[0094] Stabilize the temperature of the internal mixer at 65±2℃ and turn off the heating system;

[0095] Add phenyl silicone resin microspheres three times, each time with an interval of 5 minutes. The addition order is:

[0096] First step: 3 parts of phenyl silicone resin microspheres (30% of the total amount of phenyl silicone resin microspheres), rotation speed 15 rpm;

[0097] Second time: 4 parts of phenyl silicone resin microspheres (40% of the total amount of phenyl silicone resin microspheres), rotation speed 20 rpm;

[0098] The third time: 3 parts of phenyl silicone resin microspheres (30% of the total amount of phenyl silicone resin microspheres), the rotation speed is 25 rpm;

[0099] After the last addition, continue mixing for 10 minutes to form a rubber compound. By gradually increasing the speed, a gradient distribution of phenyl silicone resin microspheres in the matrix is ​​achieved. If bubbles appear on the surface of the rubber compound, it may be due to insufficient vacuum or high moisture content of the filler. In this case, the second stage vacuum mixing time can be extended to 40 minutes, or the filler can be dried at 150°C for 4 hours in advance.

[0100] Among them, adding materials in batches can prevent the phenyl silicone resin microspheres from breaking due to excessive local concentration; the step-by-step speed increase ensures that the surface of the phenyl silicone resin microspheres forms a physical entanglement with the rubber matrix rather than a chemical bond, thereby retaining the integrity of the cavity structure.

[0101] Step 4: Vulcanization molding

[0102] One-stage vulcanization (compression molding):

[0103] Cut the rubber mix into sheets with a thickness of 5 mm and place them into a mold preheated to 170°C;

[0104] Pressurization in two stages:

[0105] 0-5 minutes: Slowly increase the pressure to 8MPa to expel internal bubbles;

[0106] 5-15 minutes: Rapidly increase the pressure to 12 MPa to promote the formation of a cross-linked network;

[0107] After the vulcanization is completed, the mold is immediately immersed in liquid nitrogen (-196°C) for rapid cooling for 10 seconds to lock the phenyl silicone resin microsphere structure.

[0108] Second stage vulcanization (post-curing):

[0109] The program-controlled temperature box is used to perform step-by-step temperature increase, which is divided into three stages. The specific stage temperatures and corresponding functions are shown in Table 3 below:

[0110] Table 3:

[0111] stage temperature time Function 1 120℃ 1h Eliminate residual stress and prevent warping 2 150℃ 1h Promote the coordination of cerium oxide and fluorosilicone oil 3 200℃ 4h Complete deep cross-linking and stable performance

[0112] The di-2,5-bis( ...

[0113] The embodiments of the present invention are described in detail above, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and the changes still fall within the scope of protection of the present invention.

Claims

1. A silicone rubber material for sealing a nuclear power plant, characterized in that: The silicone rubber material comprises the following raw materials in parts by weight: 100 parts of methylphenyl silicone rubber; 50-60 parts of modified fumed silica; 5-15 parts of phenyl silicone resin microspheres; 3-8 parts of nano-boron nitride treated with silane coupling agent; 1.5-2.5 parts of double 2,5 curing agent; 0.5-1.2 parts of vinyltrimethoxysilane; 2-5 parts of hydroxyfluorosilicone oil; 1-3 parts of nano-cerium oxide; The phenyl content of the phenyl silicone resin microspheres is 40-60 mol%, the particle size is 5-15 μm, and the wall thickness is 1-3 μm; the particle size of the nano boron nitride is 20-50 nm, and the surface is treated with γ-aminopropyltriethoxysilane.

2. A silicone rubber material for nuclear power plant sealing and a preparation method thereof according to claim 1, characterized in that: The methylphenyl silicone rubber has a phenyl content of 18 to 25 mol%, a vinyl content of 0.8 to 1.2 mol%, and a molecular weight of 800,000 to 1,000,000.

3. The silicone rubber material for nuclear power plant sealing and the preparation method thereof according to claim 1, characterized in that: The modified fumed silica is fumed silica treated with hexamethyldisilazane for hydrophobicity, and has a specific surface area of ​​200 to 300 m 2 / g, the amount of hydrophobic treatment agent is 3-5% of the weight of white carbon black.

4. The silicone rubber material for nuclear power plant sealing and the preparation method thereof according to claim 1, characterized in that: The dosage of the nano boron nitride is 4 to 6 parts, and the mass ratio of γ-aminopropyltriethoxysilane to nano boron nitride during the silane coupling agent treatment is 1:10 to 1:

15.

5. The silicone rubber material for nuclear power plant sealing and the preparation method thereof according to claim 1, characterized in that: The fluorine content of the hydroxyl fluorosilicone oil is 10±0.5%, the viscosity is 800±50 mPa·s, and the weight ratio of the hydroxyl fluorosilicone oil to the nano-cerium oxide is 3:1 to 5:

1.

6. A method for preparing the silicone rubber material according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) Dynamic pre-crosslinking: Mix the methylphenyl silicone rubber and hydroxyl fluorosilicone oil in an internal mixer at 80-100°C and 25-35 rpm for 15-20 minutes; (2) Gradient filler dispersion: modified fumed silica and nano-boron nitride were added in two stages: the first stage was mixed at 110-120°C for 20 minutes, and the second stage was mixed at 60°C and a vacuum degree of -0.08 to -0.1 MPa for 30 minutes; (3) Functional additive compounding: Phenyl silicone resin microspheres were added three times with an interval of 5 min, the mixing temperature was less than or equal to 70 °C, and the total time was 40 min; (4) Vulcanization molding: The first stage vulcanization adopts a temperature of 170℃, pressurized vulcanization for 15 minutes, and a pressure of 8-10MPa. The second stage vulcanization adopts a step-by-step temperature rise program, at a temperature of 120℃, pressurized vulcanization for 1 hour, then at a temperature of 150℃, pressurized vulcanization for 1 hour, and finally at a temperature of 200℃, pressurized vulcanization for 4 hours.

7. The preparation method according to claim 6, characterized in that: In step (2), nano boron nitride is added in two times, 50-60% of the total amount is added in the first time, and the remaining amount is added in the second time, and nano cerium oxide is added simultaneously during the second time.

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