Low-temperature ceramic room-temperature curing silicone rubber and preparation method thereof

Abstract

The invention relates to low-temperature ceramic room-temperature curing silicone rubber and a preparation method thereof, and belongs to the technical field of high polymer materials. The silicone rubber comprises the following components in parts by weight: 100 parts of an organic silicone rubber matrix; 5-15 parts of modified zinc borate, wherein the surface of the modified zinc borate is coated with silicon dioxide modified zinc borate; 10-30 parts of low-melting-point glass powder, wherein the softening point of the low-melting-point glass powder is 350-450 DEG C; 30 to 50 parts of white carbon black; 4-16 parts of a heat-conducting filler; 2-8 parts of an interface modifier; 2-5 parts of a curing system and 0-10 parts of a processing aid. According to the invention, the modified zinc borate and low-melting-point glass powder compound is introduced as a composite fluxing agent system, and through the synergistic effect of the composite fluxing agent system and the heat-conducting filler, the ceramic initial temperature of the silicone rubber is obviously reduced, so that an effective ceramic layer can be formed at 400 DEG C or lower. The silicone rubber material can quickly form a fireproof barrier at the initial stage of a fire, effectively solves the problem of failure of fire protection of curtain wall gaps and other parts, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high polymer materials, and relates to a low-temperature ceramicized room-temperature cured silicone rubber and a preparation method thereof. BACKGROUND

[0002] In the field of building safety, curtain wall gap fire prevention is crucial. Curtain wall gap refers to the gap in the building curtain wall system due to material splicing, structure expansion or installation process, etc. These gaps will affect the sealing, waterproofing, thermal insulation and other properties of the curtain wall, and need to be treated with sealant strips, sealant and other materials to ensure the overall performance of the curtain wall.

[0003] In the field of building fire protection, traditional silicone rubber materials have been widely used as curtain wall sealing materials for a long time due to their excellent high and low temperature resistance (-60°C to 200°C) and elasticity. However, they have obvious defects in fire protection at the initial stage: the heat release rate peak of ordinary silicone rubber materials can reach 350kW / m 2 at 400°C high temperature environment, and they will quickly soften and flow, not only losing sealing performance, but also possibly helping the spread of fire, leading to serious safety hazards.

[0004] Ceramifiable silicone rubber composite material is a new type of fireproof material developed in recent years, which can form a ceramic layer with certain strength and integrity at high temperature, playing a role in heat insulation, oxygen insulation and flame spread prevention. However, the ceramicization temperature of traditional silicone rubber is usually above 800°C, which cannot form an effective fireproof barrier at the initial stage of fire (around 400°C). For example, in actual engineering application, a conventional ceramifiable silicone rubber was used to seal the curtain wall gap of a commercial complex, and in the simulated fire test, the sealing material did not form an effective ceramic layer after 400°C high temperature for 5 minutes, resulting in the flame penetrating the gap and spreading to the adjacent area.

[0005] Therefore, it is of important theoretical significance and practical application value to develop a room-temperature cured silicone rubber material that can start ceramicization at a lower temperature. SUMMARY

[0006] The application aims to provide a low-temperature ceramicized room-temperature cured silicone rubber and a preparation method thereof, which has the characteristic of low ceramicization temperature.

[0007] The purpose of the application can be achieved by the following technical solutions: A low-temperature ceramicized room-temperature cured silicone rubber, comprising the following components by weight fraction: 100 parts of silicone rubber matrix; 5-15 parts of modified zinc borate; 10-30 parts of low-melting-point glass powder; White carbon black 30-50 parts; Thermal conductive filler 4-16 parts; Interface modifier 2-8 parts; Curing system 2-5 parts; and Processing aid 0-10 parts.

[0008] The traditional silicon rubber ceramic mechanism is that the traditional silicon rubber is oxidized and decomposed at high temperature, and the main component of polydimethylsiloxane (PDMS) will form amorphous silicon dioxide. Silicon dioxide reacts with other inorganic fillers in the system to form a liquid phase, which connects the filler particles and promotes densification, thereby forming ceramic. At lower temperatures, the ceramic residue may have more pores and unreacted silicon dioxide. As the temperature rises above 800°C, the network structure of the residue becomes more dense, the crystal growth is more perfect, the porosity is reduced, and the strength is increased. Therefore, traditional ceramicization requires high temperature above 800°C.

[0009] Further, the softening point of the low-melting glass powder is 350-450°C.

[0010] In the technical solution, low-melting glass powder is introduced as a fluxing agent and a ceramic-forming promoter, which can melt to form a liquid phase at a relatively low temperature (such as 400-500°C). This liquid phase is beneficial to the flow, diffusion, dissolution, and precipitation of substances, thereby promoting the connection of fillers and the ceramicization reaction at a lower temperature. Moreover, when the glass powder melts, it can act as a framework to prevent the loss of the liquid phase, significantly improving the strength of the ceramic.

[0011] White carbon black, as a reinforcing agent, not only improves the mechanical properties of silicon rubber, but also has a large specific surface area and high surface energy, which can improve the sintering kinetics and reaction speed. In addition, it can effectively migrate, making the reaction more uniform, thereby completing sintering at a lower temperature and serving as a framework to support the liquid phase.

[0012] Zinc borate, as a fluxing agent and flame retardant, releases boron oxide during the ceramicization of silicon rubber. Boron oxide is a low-melting glass phase that can melt at temperatures of 300-450°C to form a liquid phase. This liquid phase can fill the gaps between filler particles, promote the connection and sintering densification of filler particles, thereby reducing the ceramicization temperature and improving the mechanical strength of the ceramic residue, acting as a fluxing agent.

[0013] Boron oxide and low-melting glass powder participate in the formation of the network structure of the residue at different temperature regions, continuously generating a liquid phase during the ceramicization process. As the temperature rises, the network structure of the ceramic residue becomes more and more dense, providing better protection for heat transfer and mass loss.

[0014] Further, the modified zinc borate is nano-sized zinc borate.

[0015] Nanoscale zinc borate particles have greater specific surface area and higher surface energy, which can improve reactivity and dispersion uniformity, thus possibly promoting ceramization at lower temperatures.

[0016] Further, the modified zinc borate is a zinc borate coated with silica modification. This improves the dispersibility of zinc borate in the silicone rubber matrix and possibly synergistically enhances the flame retardation and ceramization effects. For example, ZnB-SiO2 particles can migrate to the surface of the combustion zone, increasing the local concentration and forming a dense carbon layer.

[0017] Zinc borate can also react with SiO2 produced by the decomposition of silicone rubber and other inorganic fillers to form new ceramic phases, further improving the strength and stability of the ceramic residue.

[0018] Further, the silicone rubber matrix is a methyl vinyl silicone rubber and / or a methyl phenyl vinyl silicone rubber.

[0019] In this way, the silicone rubber matrix provides the basic elasticity and mechanical performance framework for the material.

[0020] Further, the thermally conductive filler is at least one of boron nitride, aluminum oxide, silicon carbide, and graphene.

[0021] Preferably, the thermally conductive filler is a boron nitride and aluminum oxide composite.

[0022] Although boron nitride does not directly reduce the ceramization temperature, its high thermal conductivity helps to quickly transfer heat at the initial stage of the fire, accelerates the overall ceramization process, and improves the thermal management performance of the final ceramic residue. The addition of aluminum oxide not only improves the thermal conductivity of the material, but also enhances the structural strength after ceramization.

[0023] Further, the mass ratio of boron nitride to aluminum oxide is 1:1.

[0024] Boron nitride has a layered structure, and the thermal conduction direction is mainly in the plane; aluminum oxide is in the form of particles, which can fill the interlayer gaps of boron nitride. A 1:1 ratio can form a "layered-particle" composite thermal conduction network. This uniform thermal conduction network can ensure rapid heat transfer at the initial stage of the fire, avoid local temperature lag, and enable the modified zinc borate and low-melting glass powder to melt and react synchronously at around 400°C, promoting the uniform formation of the ceramic layer and reducing ceramization defects caused by uneven heat distribution. At the same time, boron nitride is relatively soft and has little effect on the toughness of the silicone rubber matrix; aluminum oxide is hard and can enhance the rigidity of the material but easily lead to increased brittleness. A 1:1 ratio can strike a balance between the two.

[0025] Further, the interface modifier is a silane coupling agent.

[0026] Therefore, the addition of the interface modifier can improve the compatibility between the inorganic filler and the organic matrix, and enhance the interface bonding force.

[0027] Specifically, the silane coupling agent is KH-560 or KH-550.

[0028] Further, the curing system is a composite system of a vulcanizing agent and a catalyst, the vulcanizing agent is a double tetra vulcanizing agent or benzoyl peroxide, and the catalyst is platinum catalyst or stannous octoate.

[0029] The double tetra vulcanizing agent is 2,5-dimethyl-2,5-di(tert-butyl peroxy) hexane, which initiates the crosslinking reaction as a vulcanizing agent, and the platinum catalyst catalyzes the crosslinking process, together ensuring the material to be cured at room temperature.

[0030] Further, the processing aid includes at least one of a mineral filler, a plasticizer, a lubricant, a dispersant, an anti-scorching agent, a tackifier, and a defoaming agent.

[0031] Further, the mineral filler is mica or kaolin.

[0032] The mineral filler remains structurally stable at high temperatures and can react with fluxing agents and silica to form a high-strength ceramic skeleton.

[0033] Further, the plasticizer is hydroxyl silicone oil or polydimethylsiloxane, and the amount is 4-8 parts by weight.

[0034] The lubricant is zinc stearate, and the amount is 1-3 parts by weight. The lubricant can reduce the friction between the rubber and the equipment during mixing, prevent the phenomenon of sticking to the roller, and at the same time help the uniform dispersion of the filler.

[0035] The dispersant is triethylhexyl phosphate, and the amount is 0.5-2 parts by weight. The dispersant can reduce the friction between the rubber and the equipment during mixing, prevent the phenomenon of sticking to the roller, and at the same time help the uniform dispersion of the filler.

[0036] The anti-scorching agent is N-cyclohexyl thio phthalimide, and the amount is 0.1-0.5 parts by weight. The anti-scorching agent can prolong the scorching time of the rubber, prevent premature vulcanization during mixing or storage, and ensure the safety and stability of the processing process.

[0037] The tackifier is terpene resin, and the amount is 2-5 parts by weight. The tackifier can improve the bonding strength of silicone rubber and other materials, and enhance the sealing effect.

[0038] Further, the defoaming agent is a silicone defoaming agent, and the amount is 0.1-0.3 parts by weight. The defoaming agent can eliminate the bubbles generated during mixing, avoid the formation of defects after curing, and affect the mechanical properties and fireproof effect of the material.

[0039] The preparation method of the low-temperature ceramicized room-temperature cured silicone rubber comprises the following steps: S1, adding an organic silicone rubber matrix into an open mill for plasticizing and softening, and then sequentially adding modified zinc borate, low-melting-point glass powder, heat-conducting filler, white carbon black, interface modifier and processing aid for mixing and dispersing; S2, performing vacuum degassing treatment on the mixture of step S1; S3, adding a curing system and continuing mixing, and then injecting into a preset mold for molding; S4, placing the molded sample at room temperature for 20-40 hours for full curing.

[0040] Further, in step S1, the low-melting-point glass powder, modified zinc borate and heat-conducting filler are pre-dried. The temperature for mixing and dispersing is 40-60°C.

[0041] Further, the preparation method of the modified zinc borate comprises the following steps: A1, dispersing zinc borate in an ethanol solution containing a siloxane precursor, adjusting the pH to 9.5-10.5, and stirring at a speed of 800-1200 rpm for 3-5 hours to make the siloxane precursor hydrolyze and condense on the surface of the zinc borate to form a silica coating layer; A2, adding a silane coupling agent to the mixture of A1 and stirring to form a chemical grafting modification layer on the surface of the silica; A3, filtering and drying the mixture obtained in step A2 to obtain modified zinc borate.

[0042] Further, the siloxane precursor is tetraethyl orthosilicate, methyl triethoxysilane or ethyl triethoxysilane. In the ethanol solution, the mass ratio of anhydrous ethanol to deionized water is 3-5:1. The mass percentage of the siloxane precursor in the ethanol solution is 2-4%. The mass ratio of the zinc borate to the ethanol solution containing the siloxane precursor is 1:3-4.

[0043] In the technical solution, a silica coating layer is formed on the surface of the zinc borate particles, which can improve the problem that zinc borate as an inorganic filler causes agglomeration or weak interface bonding due to large polarity difference with the organic silicone rubber matrix. The silica coating layer can form chemical bonding with the hydroxyl groups on the surface of the zinc borate, and can also produce compatibility with the organic groups of the organic silicone rubber matrix through subsequent modification of the silane coupling agent, which is equivalent to building a molecular bridge between the inorganic filler and the organic matrix to reduce interface defects.

[0044] In addition, the silica coating layer can delay the decomposition rate of zinc borate at high temperature, so that it can more stably release the fire-retardant component at the initial stage of fire to form a fire-retardant barrier. Meanwhile, the silica itself as an inorganic inert filler can enhance the compactness of the carbon layer structure. The silica coating layer can also form a more compact chemical bond with the silicate component in the low-melting-point glass powder, reduce the melting temperature, promote the ceramization at low temperature, and promote the uniform distribution of the ceramic phase.

[0045] Advantages of the present application: (1) The present application aims to significantly reduce the ceramization starting temperature of silicone rubber by introducing a modified zinc borate and low-melting-point glass powder composite as a composite fluxing agent system, and the synergistic effect with the heat-conducting filler, so that it can form an effective ceramic layer at 400°C or lower. At the same time, a reasonable curing system is adopted to realize room temperature curing of the material, ensuring the elasticity and mechanical properties of the material in daily use. The silicone rubber material can quickly form a fireproof barrier at the initial stage of fire, effectively solving the problem of fire protection failure at curtain wall gaps and other parts, and has a broad application prospect. DETAILED DESCRIPTION

[0046] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined application purpose, the specific embodiments, structures, features and effects according to the present application are described in detail as follows in combination with examples.

[0047] Example 1 A low-temperature ceramization room temperature curing silicone rubber comprises the following components by weight fraction: The preparation method of the modified zinc borate is as follows: A1, 30 parts by weight of zinc borate is added to 100 parts by weight of an ethanol aqueous solution, wherein the ethanol aqueous solution contains 3% of tetraethyl orthosilicate by mass percentage, and the mass ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution is 4:1; then, ultrasonic dispersion is performed at 60°C for 30 minutes, glacial acetic acid is used to adjust the pH to 10±0.2, and continuous stirring is performed at a speed of 1000 rpm for 4 hours, so that the siloxane precursor is hydrolyzed and condensed on the surface of the zinc borate to form a silica coating layer.

[0048] A2, the KH-560 silane coupling agent pre-hydrolyzed is added to the above mixture, and stirring is continued for 30 minutes, so that the KH-560 reacts with the hydroxyl groups on the surface of the silica to form a chemical grafting modification layer.

[0049] A3, the mixture obtained in step A2 is filtered, then placed in a vacuum drying oven at 120°C for drying for 2 hours, and then ground into fine powder to obtain the modified zinc borate.

[0050] The preparation method of the low-temperature ceramicized room temperature curing silicone rubber comprises the following steps: S1, dry the low-melting-point glass powder, boron nitride, aluminum oxide and white carbon black in an 80°C oven for 6h; S2, plasticize the methyl vinyl silicone rubber on a two-roll open mill, and control the mixing temperature of the two-roll open mill at 40°C; S3, add the modified zinc borate to the methyl vinyl silicone rubber, and mix on the two-roll open mill until uniformly dispersed; S4, add the low-melting-point glass powder, boron nitride and aluminum oxide to the methyl vinyl silicone rubber, and continue to mix until uniformly dispersed; S5, add the white carbon black and hydroxyl silicone oil, and mix until uniform to obtain a mixture; S6, perform vacuum degassing treatment on the mixture; S7, add the bis-dinitrogen tetrafluoride vulcanizing agent and platinum catalyst, and continue to mix until uniform, then pour into a pre-set mold, and perform vulcanization on a flat plate vulcanizer, with a vulcanization temperature of 150°C and a vulcanization time of 15 minutes to form a sample; S8, place the vulcanized sample at room temperature for 24h to obtain the low-temperature ceramicized room temperature curing silicone rubber.

[0051] Example 2 A low-temperature ceramicized room temperature curing silicone rubber comprises the following components by weight fraction: In the preparation method, the mixing temperature of the two-roll open mill is controlled at 50°C, and the remaining steps are the same as those of Example 1.

[0052] Example 3 A low-temperature ceramicized room temperature curing silicone rubber comprises the following components by weight fraction: In the preparation method, the mixing temperature of the two-roll open mill is controlled at 60°C, and the remaining steps are the same as those of Example 1.

[0053] Comparative Example 1 Comparative Example 1 differs from Example 2 in that the zinc borate of Comparative Example 1 is not modified, and the remaining components, preparation steps and parameters are consistent.

[0054] Comparative Example 2 Comparative Example 2 differs from Example 2 in that the low-melting-point glass powder of Comparative Example 2 is replaced by a high-melting-point glass powder with a softening point of 650°C, and the remaining components, preparation steps and parameters are consistent.

[0055] Comparative Example 3 Comparative Example 3 differs from Example 2 in that the amount of boron nitride and alumina added in Comparative Example 3 is 0, and the remaining components, preparation steps and parameters are consistent.

[0056] Comparative Example 4 Comparative Example 4 differs from Example 2 in that Comparative Example 4 replaces methyl vinyl silicone rubber with ethylene propylene diene rubber, and the remaining components, preparation steps and parameters are consistent.

[0057] Comparative Example 5 Comparative Example 5 differs from Example 2 in that Comparative Example 5 replaces methyl vinyl silicone rubber with nitrile rubber, and the remaining components, preparation steps and parameters are consistent.

[0058] Comparative Example 6 Comparative Example 6 differs from Example 2 in that Comparative Example 6 replaces white carbon black with calcium carbonate, and the remaining components, preparation steps and parameters are consistent.

[0059] Examples 1-3 and Comparative Examples 1-6 are respectively subjected to the following performance tests: (1) Mechanical property test Tensile strength and elongation at break test: The test is performed according to the standard of GB / T 528-2009 “Determination of tensile stress-strain properties of vulcanized or thermoplastic rubber”. Type I dumbbell-shaped samples are used, with a sample thickness of 2.0 mm ± 0.2 mm and a distance between marks of 25 mm. Before testing, the samples are placed in an environment of (23 ± 2) °C and a relative humidity of (50 ± 5)% for at least 24 h. A universal mechanical testing machine is used, with a tensile speed set to 500 mm / min. The machine is started until the sample breaks. The maximum tensile force (N) at the time of sample breakage is recorded, and the tensile strength (MPa) is calculated according to the formula σ = F / A, where F is the maximum tensile force (N) and A is the original cross-sectional area of the sample (mm 2 ). During the tensile test, the distance between the marks at the time of sample breakage is recorded. The elongation at break (%) is calculated according to the formula ε = [(L1-L0) / L0] x 100, where L0 is the original distance between the marks of the sample (25 mm) and L1 is the distance between the marks at the time of sample breakage (mm). Five samples are tested for each group, and the arithmetic mean is taken as the test result.

[0060] Hardness test: The test was performed according to the standard GB / T 531.1-2008 "Vulcanized or thermoplastic rubber - Determination of indentation hardness - Part 1 : method using a type A or type D durometer" using a digital type A durometer. The test was performed at a temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) %. The sample was placed on a flat and hard test table. The pressure foot of the durometer was aligned perpendicularly to the surface of the sample. The pressure was applied so that the pressure foot of the durometer contacted the surface of the sample steadily and the pressure foot was aligned perpendicularly to the surface of the sample. The hardness value was read after 1 s from the moment the durometer contacted the sample. Three samples were tested for each group and three different points were tested for each sample. The arithmetic mean of the hardness values was taken as the hardness value of the sample. The final result was the average of the values.

[0061] (2) Ceramification performance test Firstly, cuboid samples with a size of 20 mm x 10 mm x 2 mm were prepared. Three samples were tested for each group. The samples were placed in a muffle furnace and the temperature was raised at a rate of 10 °C / min from room temperature. The state of the samples was observed in real time through the observation window of the muffle furnace, or a sample was taken out every 20 °C for appearance and structure analysis. When the surface of the sample began to appear a hard and dense ceramification layer, and no obvious deformation and powder shedding occurred when the sample was touched with tweezers, the temperature at this time was recorded as the ceramification starting temperature.

[0062] (3) Bending strength test after 400 °C ablation Firstly, the standard bending samples (with a size of 80 mm x 10 mm x 4 mm) prepared were placed in an environment with a temperature of (23 ± 2) °C and a relative humidity of (50 ± 5) % for at least 24 h. The samples were placed in a muffle furnace and the temperature was raised at a rate of 10 °C / min to 400 °C. After 30 min of heat preservation, the furnace was cooled to room temperature. The ablated samples were taken out and a three-point bending test was performed using a universal mechanical testing machine. During the test, the sample was placed on two support points with a span of 30 mm, and the loading pressure head was located directly above the midpoint of the span. The pressure was applied at a rate of 5 mm / min until the sample broke. The maximum load (N) was recorded, and the bending strength (MPa) was calculated according to the formula σ = 3FL / (2bh 2 ), wherein F is the maximum load (N), L is the support span (mm), b is the sample width (mm), and h is the sample thickness (mm). Five samples were tested for each group, and the arithmetic mean was taken as the test result.

[0063] The test results are shown in Table 1.

[0064] Table 1 From the test results in Table 1, it can be seen that, compared with Comparative Examples 1-6, the silicone rubber material of the present application has better tensile strength, elongation at break and hardness, and the ceramic starting temperature is at 400°C or lower, and the bending strength after ablation at 400°C is higher, and can form an effective ceramic protective layer in the early stage of fire.

[0065] In Comparative Example 1, the ceramic starting temperature is increased and the bending strength after ablation at 400°C is reduced due to the use of unmodified zinc borate; in Comparative Example 2, the ceramic starting temperature is greatly increased due to the use of high-melting-point glass powder; and in Comparative Example 3, the ceramic starting temperature is increased and it is difficult to form an effective ceramic layer after ablation at 400°C due to the absence of a thermally conductive filler.

[0066] In Comparative Examples 4 and 5, ethylene-propylene-diene rubber and nitrile rubber are respectively used to replace methyl vinyl silicone rubber, and the ceramic starting temperature of both is greatly increased, resulting in the inability to form an effective ceramic protective layer in the early stage of fire, and the mechanical properties such as tensile strength and elongation at break are also not as good as those of the material in the present application. This further indicates that the selected silicone rubber matrix in the present application can better synergize with other components to achieve low-temperature ceramicization and good room-temperature curing performance.

[0067] In Comparative Example 6, the tensile strength, elongation at break and bending strength after ablation at 400°C of the material are all lower than those of the material in the present application after calcium carbonate is used to replace fumed silica. This indicates that fumed silica can better cooperate with other components in the low-temperature ceramicization room-temperature curing silicone rubber, effectively improving the mechanical properties and ceramic properties of the material.

[0068] It can be seen that the low-temperature ceramicization room-temperature curing silicone rubber of the present application has excellent performance, and is significantly creative and practical.

[0069] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, change, equivalent change and modification of the above embodiments made in accordance with the technical essence of the present application, without departing from the technical solution of the present application, are still within the scope of the present application.

Claims

1. A low temperature ceramic room temperature vulcanized silicone rubber characterized in that, The following components are included by weight parts: 100 parts of silicone rubber matrix; 5-15 parts of modified zinc borate, which is zinc borate coated with silica modification; 10-30 parts of low-melting-point glass powder, which has a softening point of 350-450°C; 30-50 parts of white carbon black; 4-16 parts of heat-conducting filler; 2-8 parts of interface modifier; 2-5 parts of curing system; and 0-10 parts of processing aid.

2. A cryogenic ceramicizable room temperature vulcanizing silicone rubber according to claim 1, wherein, The silicone rubber matrix is methyl vinyl silicone rubber and / or methyl phenyl vinyl silicone rubber.

3. A cryogenic ceramicizable room temperature vulcanizing silicone rubber according to claim 1, wherein, The heat-conducting filler is at least one of boron nitride, aluminum oxide, silicon carbide, and graphene.

4. A cryogenic ceramicizable room temperature vulcanizing silicone rubber according to claim 3, wherein The heat-conducting filler is a composite of boron nitride and aluminum oxide.

5. A cryogenic ceramicizable room temperature vulcanizing silicone rubber according to claim 4, wherein The mass ratio of boron nitride to aluminum oxide is 1:

1.

6. A cryogenic ceramicizable room temperature vulcanizing silicone rubber according to claim 1, wherein, The interface modifier is a silane coupling agent.

7. A cryogenic ceramicizable room temperature vulcanizing silicone rubber according to claim 1, wherein The curing system is a composite system of vulcanizing agent and catalyst, the vulcanizing agent is bis-ditetravalent vulcanizing agent or benzoyl peroxide; the catalyst is platinum catalyst or stannous octoate.

8. A cryogenic ceramicizable room temperature vulcanizing silicone rubber according to claim 1, wherein, The processing aid includes at least one of mineral filler, plasticizer, lubricant, dispersant, anti-scorching agent, tackifier, and defoaming agent.

9. A process for the preparation of a cryogenic ceramicized room temperature vulcanizing silicone rubber as claimed in any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: S1, add the silicone rubber matrix to the open mill for plasticizing and softening; then add the modified zinc borate, low-melting-point glass powder, heat-conducting filler, white carbon black, interface modifier, and processing aid in sequence, and mix and disperse; S2, perform vacuum defoaming treatment on the mixture of step S1; S3, add the curing system, continue mixing, and then inject into a preset mold for molding; S4, place the molded sample at room temperature for 20-40 hours for sufficient curing.

10. The method of claim 9, wherein, In step S1, the low-melting-point glass powder, modified zinc borate, and heat-conducting filler are pre-dried; the temperature for mixing and dispersing is 40-60°C; the preparation method of the modified zinc borate includes the following steps: A1, disperse zinc borate in an ethanol solution containing siloxane precursor, adjust the pH to 9.5-10.5, and stir at a speed of 800-1200 rpm for 3-5 hours to make the siloxane precursor hydrolyze and condense on the surface of zinc borate to form a silica coating layer; A2, add a silane coupling agent to the mixture of A1, and stir to form a chemical grafting modification layer on the surface of silica; A3, filter and dry the mixture obtained in step A2 to obtain modified zinc borate.

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