Silicone rubber, preparation method thereof and application of silicone rubber in composite insulator

Abstract

The invention relates to the technical field of external insulating materials for power equipment, in particular to silicone rubber, a preparation method thereof and application of the silicone rubber in a composite insulator. The silicone rubber is prepared from the following raw materials in parts by weight: 100 parts of methyl vinyl silicone rubber raw rubber, 5-20 parts of hydrophobic silicon dioxide aerogel powder, 3-15 parts of conductive and heat-conducting filler, 10-30 parts of modified aluminum hydroxide, 15-35 parts of fumed silica, 1-3 parts of a silane coupling agent and 2-5 parts of a structuring control agent, 1-4 parts by weight of a low surface energy auxiliary agent, and 0.5-2 parts by weight of a vulcanizing agent. The silicone rubber provided by the invention integrates long-acting hydrophobic anti-icing, active low-power-consumption ice melting and excellent arc ablation resistance, has long-term stability, and is especially suitable for high-voltage insulators in severe environments such as heavy ice areas and heavy dirty areas.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power equipment external insulation materials, and particularly relates to a silicone rubber, a preparation method thereof and application of the silicone rubber in composite insulators. BACKGROUND

[0002] Composite insulators have been widely used in power grids due to their light weight, high strength and good pollution flashover resistance. The outer sleeve and umbrella skirt of the composite insulators are usually made of high-temperature vulcanized silicone rubber. However, in winter in cold regions, the surface of the insulator is prone to icing, forming an ice bridge, which causes electric field distortion, reduces the insulation strength, and causes ice flashover accidents, seriously threatening the safety of the power grid. In addition, in a humid and polluted environment, local electric arc may occur on the surface of the insulator, and the high temperature generated by the electric arc may ablate and carbonize the silicone rubber material, forming a permanent conductive channel, and eventually leading to breakdown of the insulator.

[0003] Currently, the problem of icing on insulators is mainly solved by passive ice-repelling coating or active ice-melting devices (such as ice melting with electric heating). The passive coating (such as super-hydrophobic coating) has low mechanical strength and is prone to failure under ultraviolet aging and sand scouring, and cannot cope with severe icing. The active ice-melting device has the disadvantages of complex system, high energy consumption and high cost. In terms of arc ablation resistance, flame retardants such as aluminum hydroxide are usually added to the silicone rubber, but this often sacrifices the mechanical properties and hydrophobicity of the material.

[0004] In the prior art, anti-icing silicone rubber composites mainly achieve electric heating ice melting by adding heat-conducting fillers, but the anti-arc ablation performance of the material is not fully considered, and the material is prone to damage under long-term arc action. Arc-resistant silicone rubber focuses on improving the arc resistance, but lacks active ice-melting function and cannot solve the problem of severe icing.

[0005] Therefore, in view of the single function and difficulty in balancing of the existing composite insulator silicone rubber material in terms of anti-icing and arc ablation resistance, it is urgent to develop a new multifunctional high-performance composite insulator silicone rubber material to cope with the challenges of complex operating environments such as heavy icing areas and heavy pollution areas. SUMMARY

[0006] To solve the above technical problems, the present application provides a silicone rubber, a preparation method thereof and application of the silicone rubber in composite insulators. The silicone rubber provided by the present application integrates long-term hydrophobic anti-icing, active low-power ice melting and excellent arc ablation resistance, has long-term stability, and is particularly suitable for high-voltage insulators in harsh environments such as heavy icing areas and heavy pollution areas.

[0007] In a first aspect, the present application provides a silicone rubber, and the preparation raw materials of the silicone rubber include the following components in the following weight fractions: 100 parts by weight of methyl vinyl silicone rubber raw rubber; 5-20 parts by weight of hydrophobic silica aerogel powder; conductive and heat-conductive filler 3-15 parts by weight; modified aluminum hydroxide 10-30 parts by weight; fumed white carbon black 15-35 parts by weight; silane coupling agent 1-3 parts by weight; structure control agent 2-5 parts by weight; low surface energy aid 1-4 parts by weight; vulcanizing agent 0.5-2 parts by weight.

[0008] The hydrophobic silica aerogel powder can be 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, etc.

[0009] The conductive and heat-conductive filler can be 3 parts by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, etc.

[0010] The modified aluminum hydroxide can be 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, etc.

[0011] The fumed white carbon black can be 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, etc.

[0012] The silane coupling agent can be 1 part by weight, 2 parts by weight, 3 parts by weight, etc.

[0013] The structure control agent can be 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, etc.

[0014] The low surface energy aid can be 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, etc.

[0015] The vulcanizing agent can be 0.5 parts by weight, 1 part by weight, 1.5 parts by weight, 2 parts by weight, etc.

[0016] The silicone rubber provided by the application integrates long-term hydrophobic ice prevention, active low-power ice melting, and excellent arc ablation resistance, has long-term stability, and is especially suitable for high-voltage insulators in harsh environments such as heavy ice areas and heavy pollution areas. Specifically: Matrix and reinforcement: The silicone rubber provided by the application takes methyl vinyl silicone rubber as the matrix, provides inherent weather resistance and electrical insulation, and takes fumed white carbon black as the main reinforcing filler.

[0017] In terms of anti-icing, passive anti-icing and active ice melting can be realized at the same time. Passive anti-icing: the hydrophobic silica aerogel powder has superhydrophobicity and nano-porous structure, the superhydrophobicity of which can build a low surface energy surface, and the nano-porous structure can effectively block heat conduction, delay the icing of the silicone rubber surface, and reduce the ice adhesion. And the low surface energy additive can migrate to the surface of the material, further stabilizing the hydrophobic effect. Active ice melting: the conductive and thermal filler can build a stable and uniform three-dimensional conductive network, which can generate uniform Joule heat when powered on, realizing active and controllable ice melting from the inside to the surface of the silicone rubber material.

[0018] In terms of anti-ablation, flame retardation and arc suppression and ablation resistance enhancement can be realized. Flame retardation and arc suppression: under the high temperature of electric arc, modified aluminum hydroxide will decompose and absorb heat (Al(OH)3→Al2O3+H2O), reducing the surface temperature of the silicone rubber material, and the released water vapor can dilute the combustible gas, effectively inhibiting the sustained combustion and carbonization depth of the electric arc. Ablation resistance enhancement: the conductive and thermal filler has extremely high thermal stability and ablation resistance, and the three-dimensional network built by them can act as a physical barrier to block the penetration and expansion of the electric arc. Moreover, the high thermal conductivity of the network helps to quickly spread the local high heat of the electric arc, avoiding material melting and spattering caused by heat concentration.

[0019] The silicone rubber material provided by the application integrates the three functional modules of "heat insulation and hydrophobicity" of aerogel, "heat conduction and electrical conductivity / ablation resistance" of the conductive and thermal filler network, and "heat absorption and flame retardation" of aluminum hydroxide, realizes the integration of "prevention-melting-resistance", solves the problem of single function of the existing composite insulator under the double threat of icing and electric arc, and ensures the long-term stability of the material performance through the synergistic effect of the components.

[0020] As a preferred technical solution of the application, the specific surface area of the hydrophobic silica aerogel powder is 600-800 m 2 / g (for example, 600 m 2 / g, 650 m 2 / g, 700 m 2 / g, 750 m 2 / g, 800 m 2 / g, etc.), the average particle size is 1-20 μm (for example, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, etc.), and the contact angle is greater than 150°.

[0021] As a preferred technical solution of the application, the conductive and thermal filler includes a combination of chopped carbon fibers and fluorinated carbon nanotubes.

[0022] The fluorination treatment of the carbon nanotubes in the application can effectively improve the compatibility and dispersibility of the carbon nanotubes in the silicone rubber matrix. The chopped carbon fibers and the fluorinated carbon nanotubes synergistically act to construct a stable and uniform three-dimensional conductive network, which generates uniform Joule heat when powered on, and realizes active and controllable ice melting from the inside to the surface of the silicone rubber material. At the same time, both the carbon fibers and the carbon nanotubes have extremely high thermal stability and ablation resistance, and the three-dimensional network constructed by the two can act as a physical barrier to hinder the penetration and expansion of the electric arc. Moreover, the high thermal conductivity of the network helps to quickly spread the local high heat of the electric arc, avoiding material melting and spattering caused by heat concentration.

[0023] As a preferred technical solution of the application, the conductive and thermal conductive filler comprises 2-10 parts by weight of chopped carbon fibers and 1-5 parts by weight of fluorinated carbon nanotubes.

[0024] The chopped carbon fibers can be 2 parts by weight, 4 parts by weight, 6 parts by weight, 8 parts by weight, 10 parts by weight, etc.

[0025] The fluorinated carbon nanotubes can be 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, etc.

[0026] As a preferred technical solution of the application, the length of the chopped carbon fibers is 100-300 μm (e.g., 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, etc.), and the diameter is 7-10 μm (e.g., 7 μm, 8 μm, 9 μm, 10 μm, etc.).

[0027] As a preferred technical solution of the application, the degree of fluorination of the fluorinated carbon nanotubes is 15%-30% (e.g., 15%, 20%, 25%, 30%, etc.), the tube diameter is 10-20 nm (e.g., 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, etc.), and the length is 1-5 μm (e.g., 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.).

[0028] As a preferred technical solution of the application, the modified aluminum hydroxide is silane coupling agent surface modified aluminum hydroxide. After modification, the aluminum hydroxide changes from hydrophilic to hydrophobic, and the compatibility with the silicone rubber matrix increases, which can greatly enhance the mechanical properties of the silicone rubber. The D50 particle size of the modified aluminum hydroxide is 1-5 μm, e.g., 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, etc.

[0029] As a preferred technical solution of the application, the preparation method of the modified aluminum hydroxide comprises uniformly mixing aluminum hydroxide and silane coupling agent to obtain the modified aluminum hydroxide.

[0030] As a preferred technical solution of the present application, the mass ratio of the aluminum hydroxide to the silane coupling agent is (18-24):(0.5-2), such as 18:0.5, 20:1, 22:1, 24:2, etc.

[0031] As a preferred technical solution of the present application, the temperature for mixing is 80-100℃, such as 80℃, 85℃, 90℃, 95℃, 100℃, etc.; and the mixing time is 20-40 min, such as 20 min, 25 min, 30 min, 35 min, 40 min, etc.

[0032] The silicon rubber material provided by the present application realizes triple protection through component synergistic effect: (1) long-term hydrophobicity and super-ice repellency are provided by aerogel and low surface energy characteristics, which greatly reduces the adhesion of ice layer and inhibits rain flash and ice flash; (2) a stable three-dimensional conductive network constructed by carbon fibers and carbon nanotubes endows the material with self-heating capacity of Joule heat, which can realize active and low-power ice melting; (3) the combination of the "heat absorption-flame retardant" effect of aluminum hydroxide and the "heat conduction-burn-resistant" effect of the carbon network significantly improves the arc ablation resistance and tracking performance of the silicon rubber material, which is especially suitable for high-voltage insulators in harsh environments such as heavy ice areas and heavy pollution areas.

[0033] As a preferred technical solution of the present application, the silane coupling agent includes γ-aminopropyl triethoxysilane (KH-550) and / or γ-propyl trimethoxysilane.

[0034] As a preferred technical solution of the present application, the structural control agent includes hydroxyl silicone oil and / or hexamethyl disilazane.

[0035] As a preferred technical solution of the present application, the low surface energy additive includes perfluoroalkyl ether modified polysiloxane and / or dimethyl dimethoxysilane.

[0036] As a preferred technical solution of the present application, the vulcanizing agent includes bis-dipentasulfur agent and / or dicumyl peroxide.

[0037] In the second aspect, the present application provides a preparation method of the silicon rubber of the first aspect, which comprises the following steps: (1) mixing the hydrophobic silica aerogel powder with part of the low surface energy additive to obtain surface-activated aerogel powder; (2) putting the methyl vinyl silicone rubber raw rubber into a banbury mixer for plasticizing, and then adding fumed white carbon black, a structural control agent and modified aluminum hydroxide for mixing to obtain a silicon rubber masterbatch; (3) placing the silicone rubber masterbatch, the electrically and thermally conductive filler, the surface-activated aerogel powder of step (1), a silane coupling agent, and the remaining low-surface-energy additive into an open mill for mixing to obtain a mixed rubber; (4) uniformly mixing the mixed rubber with a vulcanizing agent and vulcanizing to obtain the silicone rubber.

[0038] The preparation method provided by the application ensures uniform dispersion and firm combination of each functional filler (especially brittle silica aerogel) and the matrix through surface modification and stage mixing of the filler, guarantees long-term stability and repeatability of the material performance, and is simple in process and easy for industrial production.

[0039] As a preferred technical solution of the application, the temperature for the mixing of step (1) is 50-70℃, such as 50℃, 55℃, 60℃, 65℃, 70℃, etc.; and the mixing time is 15-25 min, such as 15 min, 18 min, 20 min, 22 min, 25 min, etc.

[0040] As a preferred technical solution of the application, the partial low-surface-energy additive of step (1) accounts for 20-50% of the total amount of the low-surface-energy additive, such as 20%, 30%, 40%, 50%, etc.

[0041] As a preferred technical solution of the application, the plasticizing time of step (2) is 3-5 min, such as 3 min, 4 min, 5 min, etc.

[0042] As a preferred technical solution of the application, the mixing temperature of step (2) is 40-60℃, such as 40℃, 45℃, 50℃, 55℃, 60℃, etc.; and the mixing time is 20-40 min, such as 20 min, 25 min, 30 min, 35 min, 40 min, etc.

[0043] As a preferred technical solution of the application, the electrically and thermally conductive filler of step (3) is a pre-dispersed electrically and thermally conductive filler, and the pre-dispersing method is: ultrasonic dispersion of chopped carbon fibers and fluorinated carbon nanotubes in a solvent, drying to obtain the pre-dispersed electrically and thermally conductive filler. The ultrasonic dispersion time is 30-60 min, such as 30 min, 40 min, 50 min, 60 min, etc.

[0044] As a preferred technical solution of the application, the mixing temperature of step (3) is 30-45℃, such as 30℃, 35℃, 40℃, 45℃, etc.

[0045] As a preferred technical solution of the application, the vulcanizing method of step (4) includes one-stage mold vulcanization and two-stage vulcanization.

[0046] As a preferred technical solution of the present application, the vulcanization conditions of the first stage of the mold vulcanization include: the temperature is 170-180℃, for example, 170℃, 172℃, 174℃, 176℃, 178℃, 180℃, etc.; the pressure is 13-16 MPa, for example, 13 MPa, 14 MPa, 15 MPa, 16 MPa, etc.; and the time is 15-25 min, for example, 15 min, 18 min, 20 min, 22 min, 25 min, etc.

[0047] As a preferred technical solution of the present application, the vulcanization conditions of the second stage of the mold vulcanization include: the temperature is 195-205℃, for example, 195℃, 198℃, 200℃, 202℃, 205℃, etc.; and the time is 3-4 h, for example, 3 h, 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4 h, etc.

[0048] In order to more conveniently understand the preparation method of the silicone rubber of the present application, the present application further provides a flow chart of the preparation method of the silicone rubber, as shown in the specific Figure 1

[0049] In a third aspect, the present application provides an application of the silicone rubber prepared by the preparation method of the second aspect in a composite insulator.

[0050] Compared with the prior art, the technical solution provided by the embodiments of the present application has the following advantages: The silicone rubber provided by the present application integrates long-term hydrophobic ice prevention, active low-power ice melting, and excellent arc ablation resistance, has long-term stability, and is especially suitable for high-voltage insulators in harsh environments such as heavy icing areas and heavy pollution areas. BRIEF DESCRIPTION OF DRAWINGS

[0051] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, for those skilled in the art, other drawings can also be obtained from these drawings without any creative labor.

[0053] Figure 1 The flow chart of the preparation method of the silicone rubber of the present application. DETAILED DESCRIPTION

[0054] ​In order to enable a more complete understanding of the above-mentioned objects, features and advantages of the present application, the following will further describe the solutions of the present application. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0055] In the following description, a large number of specific details are set forth in order to facilitate a thorough understanding of the present application, but the present application can also be implemented in other manners different from those described herein; obviously, the embodiments described in the specification are only a part of the embodiments of the present application, and not all the embodiments.

[0056] Preparation Example 1 The present preparation example provides a modified aluminum hydroxide and a preparation method thereof, the preparation method comprising: 20 parts by weight of the modified aluminum hydroxide and 1 part by weight of KH-550 are mixed at high speed in a high-speed mixer at 90°C for 30 minutes to obtain the modified aluminum hydroxide, D50 = 3 μm.

[0057] Example 1 The present example provides a silicone rubber and a preparation method thereof, the raw materials for preparing the silicone rubber are shown in Table 1: Table 1

[0058] The preparation method comprises the following steps: (1) The chopped carbon fibers and the carbon nanotubes are ultrasonically dispersed in anhydrous ethanol for 40 min, and dried at 80°C to obtain the pre-dispersed conductive and thermal conductive filler; The hydrophobic silica aerogel powder and 1 part by weight of the low-surface-energy additive are mixed at high speed in a high-speed mixer at 60°C for 20 min to obtain the surface-activated aerogel powder; (2) The raw methyl vinyl silicone rubber is put into an internal mixer, and plasticized for 3 min, then the fumed white carbon black, the structure control agent and the modified aluminum hydroxide are added, and mixed at 50°C for 30 min, and the material is discharged to obtain the silicone rubber masterbatch; (3) The silicone rubber masterbatch is cooled to 40°C on an open mill, and the pre-dispersed conductive and thermal conductive filler, the surface-activated aerogel powder, the silane coupling agent and the remaining 1 part by weight of the low-surface-energy additive are added in sequence. Thin pass is performed for 8 times until the fillers are uniformly dispersed to obtain the mixed rubber; (4) The double-dipentasulfide curing agent is added to the mixed rubber, and after mixing, the sheet is discharged. The rubber is filled into a mold, and one-stage mold pressing vulcanization is performed at 175°C and 14 MPa for 20 min. Subsequently, post-vulcanization is performed in a 200°C oven for 3.5 h to obtain the silicone rubber.

[0059] Example 2 The embodiment provides a silicone rubber and a preparation method thereof, raw materials of the silicone rubber are shown in Table 2: Table 2

[0060] The preparation method comprises the following steps: (1) ultrasonic dispersion of short carbon fibers and fluorinated carbon nanotubes in anhydrous ethanol for 60 min, drying at 80 DEG C, to obtain pre-dispersed conductive and thermal conductive fillers; high-speed mixing of hydrophobic silica aerogel powder and 2 parts by weight of a low surface energy additive in a high-speed mixer at 70 DEG C for 15 min, to obtain surface-activated aerogel powder; (2) feeding raw methyl vinyl silicone rubber into a banbury mixer, plasticizing for 5 min, then adding fumed white carbon black, a structure control agent and modified aluminum hydroxide, mixing at 40 DEG C for 40 min, and discharging to obtain silicone rubber masterbatch; (3) cooling the silicone rubber masterbatch on an open mill to 30 DEG C, sequentially adding the pre-dispersed conductive and thermal conductive fillers, the surface-activated aerogel powder, a silane coupling agent and the remaining 2 parts by weight of the low surface energy additive, and thin passing and triangulation packaging for 12 times until the fillers are uniformly dispersed, to obtain a mixed rubber; (4) adding a vulcanizing agent to the mixed rubber, uniformly mixing and then discharging, filling the rubber into a mold, performing one-stage mold pressing vulcanization, and performing mold pressing vulcanization at 180 DEG C and 13 MPa for 15 min, then post-vulcanizing in a 205 DEG C oven for 3 h, to obtain the silicone rubber.

[0061] Example 3 The embodiment provides a silicone rubber and a preparation method thereof, raw materials of the silicone rubber are shown in Table 3: Table 3

[0062] The preparation method comprises the following steps: (1) ultrasonic dispersion of short carbon fibers and fluorinated carbon nanotubes in anhydrous ethanol for 30 min, drying at 80 DEG C, to obtain pre-dispersed conductive and thermal conductive fillers; high-speed mixing of hydrophobic silica aerogel powder and 0.5 parts by weight of a low surface energy additive in a high-speed mixer at 50 DEG C for 25 min, to obtain surface-activated aerogel powder; (2) feeding raw methyl vinyl silicone rubber into a banbury mixer, plasticizing for 4 min, then adding fumed white carbon black, a structure control agent and modified aluminum hydroxide, mixing at 60 DEG C for 20 min, and discharging to obtain silicone rubber masterbatch; (3) The silicone rubber masterbatch was cooled to 45℃ on an open mill, and the pre-dispersed conductive and thermal conductive filler, surface-activated aerogel powder, silane coupling agent, and the remaining 0.5 parts by weight of low-surface-energy additive were sequentially added. The mixture was passed through the triangle packet 6 times until the fillers were uniformly dispersed, obtaining a rubber compound; (4) The vulcanizing agent was added to the rubber compound, which was mixed and sheeted. The rubber compound was filled into a mold, and one-stage mold pressing vulcanization was performed at 170℃ and 16 MPa for 25 min. Subsequently, post-vulcanization was performed in an oven at 195℃ for 4 h, obtaining the silicone rubber.

[0063] Comparative Example 1 This comparative example provides a silicone rubber and a preparation method thereof, wherein the preparation raw materials of the silicone rubber are different from those of Example 1 in that the hydrophobic silica aerogel powder and the conductive and thermal conductive filler are not contained in the comparative example, and the remaining preparation raw materials are the same as those of Example 1, and the preparation method is the same as that of Example 1.

[0064] Comparative Example 2 This comparative example provides a silicone rubber and a preparation method thereof, wherein the preparation raw materials of the silicone rubber are different from those of Example 1 in that the modified aluminum hydroxide is not contained in the comparative example, and the remaining preparation raw materials are the same as those of Example 1, and the preparation method is the same as that of Example 1.

[0065] Performance Test The silicone rubber prepared in the examples and comparative examples was tested, and the test standards and test results are shown in Table 4: Table 4

[0066] It can be found from Table 4 that the silicone rubber material prepared in the examples of the present application is significantly better than the comparative examples in terms of hydrophobicity, low ice adhesion, active ice melting efficiency, and arc ablation resistance, and has excellent hydrophobic anti-icing, active low-power ice melting, and arc ablation resistance.

[0067] It can be found from the comparison of Example 1 and Comparative Examples 1-2 that the ice resistance of the silicone rubber material prepared in the present application is comprehensively improved, the static water contact angle can reach more than 155°, and the ice adhesion is reduced by more than 50% compared with Comparative Example 1. Under the application of a safety voltage (AC 50V), the surface of the material can be heated to above 0℃ within a few minutes, realizing rapid and low-energy ice melting. At the same time, the arc ablation resistance is significantly enhanced, and the arc track resistance grade reaches 1A4.5 or higher according to the IEC 60587 standard for inclined plate arc track test. After arc ablation, the carbonized area of the material is small and shallow, and there is no melting and dripping phenomenon.

[0068] It has to be noted that, in the present document, relational terms are intended only to convey a possible relationship between elements or

[0069] The foregoing is considered as illustrative only of the principles of the application. Numerous modifications and changes will readily occur to those skilled in the art, which modifications and changes are to be understood as intended to be encompassed by the general scope of the application. Accordingly, the application is not to be limited to the above described ones; rather, the above described ones are to serve as a basis for the claims as a support for a patent.

Claims

1. A silicone rubber, characterized in that, The raw materials for preparing the silicone rubber include the following components in parts by weight: 100 parts by weight of raw methyl vinyl silicone rubber; 5-20 parts by weight of hydrophobic silica aerogel powder; 3-15 parts by weight of conductive and thermally conductive filler; 10-30 parts by weight of modified aluminum hydroxide; 15-35 parts by weight of fumed silica; 1-3 parts by weight of silane coupling agent; 2-5 parts by weight of structure control agent; 1-4 parts by weight of low surface energy additive; Vulcanizing agent: 0.5 to 2 parts by weight.

2. The silicone rubber according to claim 1, characterized in that, The specific surface area of ​​the hydrophobic silica aerogel powder is 600~800 m². 2 / g, with an average particle size of 1~20 μm and a contact angle greater than 150°.

3. The silicone rubber according to claim 1 or 2, characterized in that, The conductive and thermally conductive filler comprises a combination of chopped carbon fibers and fluorinated carbon nanotubes. Preferably, the conductive and thermally conductive filler comprises 2-10 parts by weight of chopped carbon fibers and 1-5 parts by weight of fluorinated carbon nanotubes. Preferably, the chopped carbon fibers have a length of 100~300 μm and a diameter of 7~10 μm; Preferably, the fluorinated carbon nanotubes have a fluorination degree of 15% to 30%, a diameter of 10 to 20 nm, and a length of 1 to 5 μm.

4. The silicone rubber according to any one of claims 1 to 3, characterized in that, The modified aluminum hydroxide is a silane coupling agent surface-modified aluminum hydroxide with a D50 particle size of 1~5 μm.

5. The silicone rubber according to claim 4, characterized in that, The method for preparing the modified aluminum hydroxide includes: mixing aluminum hydroxide with a silane coupling agent to obtain the modified aluminum hydroxide; Preferably, the mass ratio of aluminum hydroxide to silane coupling agent is (18~24):(0.5~2); Preferably, the mixing temperature is 80~100℃ and the mixing time is 20-40 min.

6. The silicone rubber according to any one of claims 1 to 5, characterized in that, The silane coupling agent includes γ-aminopropyltriethoxysilane and / or γ-propyltrimethoxysilane; And / or, the structuring control agent includes hydroxyl silicone oil and / or hexamethyldisilazane; And / or, the low surface energy additives include perfluoroalkyl ether modified polysiloxanes and / or dimethyldimethoxysilanes; And / or, the vulcanizing agent includes bis(2,5-dimethyl)sulfide and / or dicumyl peroxide.

7. The method for preparing silicone rubber according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: (1) Mix hydrophobic silica aerogel powder with a portion of low surface energy additives to obtain surface-activated aerogel powder; (2) Methyl vinyl silicone rubber raw rubber is put into a mixer for plasticizing, and then fumed silica, structure control agent and modified aluminum hydroxide are added for mixing to obtain silicone rubber masterbatch. (3) The silicone rubber masterbatch, conductive and thermally conductive filler, surface-activated aerogel powder from step (1), silane coupling agent and remaining low surface energy additives are placed in a two-roll mill and mixed to obtain a compound. (4) The compound is mixed with a vulcanizing agent and vulcanized to obtain the silicone rubber.

8. The preparation method according to claim 7, characterized in that, The mixing temperature in step (1) is 50~70℃, and the mixing time is 15~25 min; And / or, the sculpting time in step (2) is 3~5 min; And / or, the mixing temperature in step (2) is 40~60℃ and the mixing time is 20~40min; And / or, the conductive and thermally conductive filler in step (3) is a pre-dispersed conductive and thermally conductive filler. The pre-dispersed method is: ultrasonically disperse short-cut carbon fibers and fluorinated carbon nanotubes in a solvent, and dry them to obtain the pre-dispersed conductive and thermally conductive filler. And / or, the mixing temperature in step (3) is 30~45℃.

9. The preparation method according to claim 7 or 8, characterized in that, The vulcanization method described in step (4) includes a single-stage compression vulcanization and a two-stage vulcanization; Preferably, the vulcanization conditions for the first-stage compression molding vulcanization include: a temperature of 170~180℃, a pressure of 13~16 MPa, and a time of 15~25 min; Preferably, the vulcanization conditions for the two-stage vulcanization include: a temperature of 195~205℃ and a time of 3~4 h.

10. The application of the silicone rubber according to any one of claims 1 to 6 or the silicone rubber prepared by the preparation method according to any one of claims 7 to 9 in composite insulators.

Images