Insulating silicone rubber material resistant to humid and hot environment, insulating silicone rubber umbrella skirt, and preparation methods

Abstract

The present application provides an insulating silicone rubber material resistant to a humid and hot environment, an insulating silicone rubber umbrella skirt, and preparation methods. The insulating silicone rubber material provided in the present application comprises, in parts by mass: 100 parts of methyl ethylene silicone rubber, 25-40 parts of white carbon black, 100-120 parts of aluminum hydroxide, 2-4 parts of a silane coupling agent, 3-7 parts of nano montmorillonite, 1-3 parts of a vulcanizing agent, and 3-5 parts of hydroxyl silicone oil, wherein aluminum hydroxide comprises first aluminum hydroxide and second aluminum hydroxide, the particle size of the first aluminum hydroxide is 0.5-1.5 µm, the particle size of the second aluminum hydroxide is 4-6 µm, and the mass ratio of the first aluminum hydroxide to the second aluminum hydroxide is 5-7:1. According to the present application, the first aluminum hydroxide having the particle size of 0.5-1.5 µm and the second aluminum hydroxide having the particle size of 4-6 µm are selected and used in conjunction as a filler, so that the water absorption characteristic is effectively improved, the thermal conductivity is effectively improved, and then the polarization loss and abnormal heating in a humid and hot environment are effectively reduced.

Description

Insulating silicone rubber material resistant to hot and humid environments, insulating silicone rubber shed and preparation method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the Patent Office of China on June 16, 2023, with application number "202310725974.5" and application name "Insulating silicone rubber material, insulating silicone rubber umbrella skirt and preparation method", all contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of silicone rubber materials, and in particular to an insulating silicone rubber material resistant to hot and humid environments, an insulating silicone rubber shed, and a preparation method. Background Art

[0004] Composite insulators have excellent pollution flashover resistance and are well-suited to various polluted environments. They are widely used in the Southern Power Grid. However, with the rapid increase in their use, reports of defects such as abnormal heating have increased. This phenomenon is particularly severe in southern China, where temperatures and humidity are high, posing a serious threat to the safe operation of transmission lines.

[0005] Previous research has shown that polarization heating caused by moisture absorption in silicone rubber has a significant impact on the heating of the high-voltage side of composite insulators. Because the silicone rubber in heat-generating composite insulators has a loose and porous structure, it easily absorbs water, resulting in a significant increase in dielectric power loss when wet.

[0006] Based on this, optimizing the dielectric properties of silicone rubber materials for composite insulators has important research significance for suppressing abnormal heating of composite insulators in humid and hot areas.

[0007] Summary of the Invention

[0008] The main purpose of this application is to provide an insulating silicone rubber material, an insulating silicone rubber shed and a preparation method that are resistant to hot and humid environments, so as to solve the problem in the prior art that the heat-generating composite insulation has a loose and porous pore structure of silicone rubber and is extremely easy to absorb water, resulting in a significant increase in dielectric loss power after being damp.

[0009] In order to achieve the above-mentioned purpose, according to one aspect of the present application, an insulating silicone rubber material is provided, which includes, by mass, 100 parts of methyl vinyl silicone rubber, 25-40 parts of white carbon black, 100-120 parts of aluminum hydroxide, 2-4 parts of silane coupling agent, 3-7 parts of nano-montmorillonite, 1-3 parts of vulcanizing agent and 3-5 parts of hydroxy silicone oil, wherein the aluminum hydroxide includes a first aluminum hydroxide and a second aluminum hydroxide, the particle size of the first aluminum hydroxide is 0.5-1.5 μm, the particle size of the second aluminum hydroxide is 4-6 μm, and the mass ratio of the two is 5-7:1.

[0010] Furthermore, the methyl vinyl silicone rubber includes a first silicone rubber and a second silicone rubber, the number average molecular weight of the first silicone rubber is 600,000 to 700,000, the mass content of vinyl is 2.5 to 3.5%, and the mass ratio of the first silicone rubber to the second silicone rubber is 1:1.5 to 2.

[0011] Furthermore, the white carbon black is fumed white carbon black with a specific surface area of ​​150 to 300 m 3 / g.

[0012] Further, the silane coupling agent includes at least one of KH550, KH560 or KH570; and / or the vulcanizing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0013] Furthermore, the nano-montmorillonite is organically modified nano-montmorillonite; and / or the hydroxyl content of the hydroxy silicone oil is 3.5-4.5% by weight. Furthermore, the insulating silicone rubber material further comprises 3-5 parts by weight of a colorant, preferably iron oxide with a particle size of 0.5-1.5 μm, and further preferably, the surface of the iron oxide is hydrophobically treated.

[0014] According to another aspect of the present application, a method for preparing an insulating silicone rubber material is also provided, which comprises: mixing, refining, and vulcanizing methyl vinyl silicone rubber, white carbon black, a first aluminum hydroxide, a second aluminum hydroxide, a silane coupling agent, a vulcanizing agent, nano-montmorillonite, a vulcanizing agent, hydroxyl silicone oil, and an optional colorant to obtain an insulating silicone rubber material.

[0015] Furthermore, the vulcanization molding temperature is 165-185° C., the pressure is 10-12 MPa, and the time is 10-14 minutes.

[0016] According to a third aspect of the present application, an insulating silicone rubber shed is further provided. The material of the insulating silicone rubber shed is any insulating silicone rubber material provided in the first aspect.

[0017] According to a fourth aspect of the present application, a method for preparing the above-mentioned insulating silicone rubber shed is also provided, which comprises: placing the insulating silicone rubber material into a mold and performing hot pressing molding to obtain the insulating silicone rubber shed.

[0018] Furthermore, the temperature of the hot pressing molding is 170-190° C., the pressure is 10-15 MPa, and the time is 15-20 minutes.

[0019] The technical solution provided by this application utilizes a first aluminum hydroxide with a particle size of 0.5 to 1.5 μm and a second aluminum hydroxide with a particle size of 4 to 6 μm, which are combined as fillers. This effectively improves the water absorption and thermal conductivity of the insulating silicone rubber material provided by this application, thereby effectively reducing polarization loss and abnormal heating in hot and humid environments. Furthermore, the insulating silicone rubber material provided by this application exhibits excellent mechanical properties and pollution flashover resistance, and has broad application prospects. DETAILED DESCRIPTION

[0020] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the embodiments.

[0021] As analyzed in the background of this application, existing heat-generating composite insulation materials suffer from a problem where the dielectric loss power increases significantly when exposed to moisture due to the loose and porous structure of the silicone rubber. To address this problem, this application provides an insulating silicone rubber material, an insulating silicone rubber shed, and a preparation method.

[0022] In a typical embodiment of the present application, an insulating silicone rubber material is provided, which includes, by mass, 100 parts of methyl vinyl silicone rubber, 25-40 parts of white carbon black, 100-120 parts of aluminum hydroxide, 2-4 parts of silane coupling agent, 3-7 parts of nano-montmorillonite, 1-3 parts of vulcanizing agent and 3-5 parts of hydroxy silicone oil, wherein the aluminum hydroxide includes a first aluminum hydroxide and a second aluminum hydroxide, the particle size of the first aluminum hydroxide is 0.5-1.5 μm, the particle size of the second aluminum hydroxide is 4-6 μm, and the mass ratio of the two is 5-7:1.

[0023] In order to ensure excellent pollution flashover resistance, a large amount of aluminum hydroxide is filled in the insulating silicone rubber material. The applicant has found through research that when the particle size of aluminum hydroxide is large, the prepared insulating silicone rubber material has a higher thermal conductivity. This is because under the same filling mass, the amount of aluminum hydroxide with larger particle size is larger, and the interface in contact with the silicone rubber matrix is ​​less, resulting in a smaller thermal resistance. In addition, aluminum hydroxide with larger particle size is easier to form a heat conduction channel than aluminum hydroxide with smaller particle size, thereby making the thermal conductivity of the insulating silicone rubber material higher. However, aluminum hydroxide with smaller particle size has a larger specific surface area and more bonding interfaces with the silicone rubber matrix, which is more conducive to improving the mechanical properties of the insulating silicone rubber material. However, aluminum hydroxide with smaller particle size provides more space for water to bind to the specific surface, which will result in a higher water absorption rate, which is not conducive to reducing polarization loss and abnormal heat in a humid and hot environment.

[0024] Furthermore, the larger-sized second aluminum hydroxide has a smaller specific surface area than the smaller-sized first aluminum hydroxide, resulting in a smaller interface area with the silicone rubber. This allows for a stronger thermal conductivity path between the two particles, resulting in a thinner rubber layer between the particles and, consequently, lower heat transfer resistance. Silicone rubber is inherently a poor conductor of heat, and its improved thermal conductivity depends on the effective packing of thermally conductive fillers to form thermal pathways. Within a certain particle size range, larger-sized second aluminum hydroxide particles exhibit higher thermal conductivity due to fewer interfaces with the matrix and lower thermal resistance. However, at a certain aluminum hydroxide dosage, effective interparticle packing becomes a critical factor. A mixed packing of large and small-sized first and second aluminum hydroxide particles is more effective than a single-sized packing. This is because the smaller-sized first aluminum hydroxide particles can enter spaces that the larger-sized second aluminum hydroxide particles cannot occupy. Within the gaps between the larger-sized second aluminum hydroxide particles, the larger-sized second aluminum hydroxide and the smaller-sized first aluminum hydroxide particles form a tighter packing. This packing creates more points of contact between the particles, resulting in a greater number of thermal pathways. Therefore, a combination of large and small-sized first and second aluminum hydroxide particles can effectively improve the thermal conductivity of rubber and reduce thermal resistance. In addition, the combination of large and small particle sizes of the first aluminum hydroxide and the second aluminum hydroxide can effectively improve the mechanical properties of the silicone rubber. The small particle size of the first aluminum hydroxide is beneficial to the mechanical strength, and the addition of the large particle size of the second aluminum hydroxide can reduce the viscosity of the system. Therefore, the compounding of the first aluminum hydroxide and the second aluminum hydroxide can optimize the heat dissipation, mechanical and aging properties of the insulating silicone rubber.

[0025] The technical solution provided by this application utilizes a first aluminum hydroxide with a particle size of 0.5 to 1.5 μm and a second aluminum hydroxide with a particle size of 4 to 6 μm as fillers. This effectively improves the water absorption properties and thermal conductivity of the insulating silicone rubber material provided by this application, thereby effectively reducing polarization loss and abnormal heating in hot and humid environments. The insulating silicone rubber material provided by this application also has excellent mechanical properties and pollution flashover resistance, and has broad application prospects.

[0026] In this application, "particle size" refers to the average particle size D50.

[0027] In the insulating silicone rubber material provided in the present application, the methyl vinyl silicone rubber is 100 parts by mass, the mass fraction of white carbon black is 25 parts, 28 parts, 30 parts, 32 parts, 35 parts, 38 parts, 40 parts or a range value consisting of any two numerical values; the mass fraction of aluminum hydroxide is 100 parts, 102 parts, 105 parts, 108 parts, 110 parts, 112 parts, 115 parts, 118 parts, 120 parts or a range value consisting of any two numerical values; the mass fraction of silane coupling agent is 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or a range value consisting of any two numerical values; the mass fraction of nano-montmorillonite is The mass fraction of the sulfiding agent is 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts, 2.5 parts, 3 parts or a range of values ​​consisting of any two values; the mass fraction of the hydroxy silicone oil is 3 parts, 3.2 parts, 3.5 parts, 3.8 parts, 4 parts, 4.5 parts, 5 parts or a range of values ​​consisting of any two values; the particle size of the first aluminum hydroxide is 0.5 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.5 μm or a range of values ​​consisting of any two values; the particle size of the second aluminum hydroxide is 4 μm, 4.2μm, 4.5μm, 4.8μm, 5μm, 5.2μm, 5.5μm, 5.8μm, 6μm or a range value consisting of any two values; the mass ratio of the first aluminum hydroxide to the second aluminum hydroxide is, for example, 5:1, 5.5:1, 6:1, 6.5:1, 7:1 or a range value consisting of any two values.

[0028] [Aluminum hydroxide]

[0029] Aluminum hydroxide includes active aluminum hydroxide and inactive aluminum hydroxide. Since active aluminum hydroxide may have a negative impact on the electrical corrosion resistance of the insulating silicone rubber material and may inhibit the effect of the vulcanizing agent, and is also expensive, the first aluminum hydroxide and the second aluminum hydroxide selected in this application are preferably inactive aluminum hydroxide to reduce the cost, reduce the impact on the electrical corrosion resistance of the insulating silicone rubber material, and avoid inhibiting the effect of the vulcanizing agent.

[0030] [Methyl vinyl silicone rubber]

[0031] In order to further improve the mechanical properties of the insulating silicone rubber material, the methyl vinyl silicone rubber preferably includes a first silicone rubber and a second silicone rubber, the number average molecular weight of the first silicone rubber is 600,000 to 700,000, and the mass content of the vinyl group is 0.15 to 0.20%; the number average molecular weight of the second silicone rubber is 600,000 to 700,000, and the mass content of the vinyl group is 2.5 to 3.5%, and the mass ratio of the two is 1:1.5 to 2.

[0032] The number average molecular weights of the first and second silicone rubbers may be 600,000, 620,000, 650,000, 680,000, or 700,000, or any range consisting of two values; the vinyl content of the first silicone rubber may be 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.20%, or any range consisting of two values; and the vinyl content of the second silicone rubber may be 2.5%, 2.8%, 3.0%, 3.2%, or 3.5%, or any range consisting of two values. The weight ratio of the first and second silicone rubbers may be 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, or 1:2.0, or any range consisting of two values.

[0033] [Silica]

[0034] In order to further improve the mechanical properties of insulating silicone rubber materials, the preferred silica is fumed silica with a surface area of ​​150 to 300 m 3 / g (such as 150m 3 / g, 180m 3 / g, 200m 3 / g, 220m 3 / g, 250m 3 / g, 280m 3 / g、300m 3 / g, etc.). The chemical inertness and special thixotropy of fumed silica can significantly improve the tensile strength, tear resistance and wear resistance of rubber materials.

[0035] [Silane coupling agent]

[0036] The use of a silane coupling agent facilitates a more uniform dispersion of silica in the silicon matrix and a more stable interface between silica and the silicon matrix. The specific type of silane coupling agent is not specifically limited and includes but is not limited to any one of KH550, KH560, or KH570, or a mixture of two or more silane coupling agents.

[0037] [Vulcanizing agent]

[0038] The specific type of the above-mentioned vulcanizing agent is not particularly limited, and any vulcanizing agent commonly used in the art can be used, including but not limited to 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, etc.

[0039] [Nano-montmorillonite]

[0040] Montmorillonite has unique layered one-dimensional nanostructure characteristics, morphological characteristics, designable reactivity between layers, and large specific surface area (750m 2 / g) and a diameter / thickness ratio of over 200. Nano-montmorillonite has a smaller particle size, which is more conducive to uniform dispersion in the silicon matrix, improving the thermal stability and dimensional stability of the insulating silicone rubber material.

[0041] In order to further improve the compatibility between the nano-montmorillonite and the silicone rubber matrix, the nano-montmorillonite is preferably an organically modified nano-montmorillonite, which can generally be purchased commercially.

[0042] [Hydroxy silicone oil]

[0043] The mixing efficiency is improved by adding hydroxy silicone oil to the insulating silicone rubber material provided in the present application. The hydroxy silicone oil is a commonly used hydroxy silicone oil in this field. From the perspective of improving the mixing efficiency, the hydroxy content in the hydroxy silicone oil is preferably 3.5-4.5% (such as 3.5%, 3.8%, 4.0%, 4.2%, 4.5%).

[0044] [Colorant]

[0045] In order to obtain a suitable color, in some embodiments of the present application, the insulating silicone rubber material further includes 3 to 5 parts by weight of a colorant (e.g., 3 parts, 3.2 parts, 3.5 parts, 3.8 parts, 4.0 parts, 4.2 parts, 4.5 parts, 4.8 parts, 5 parts, etc.). Based on the commonly used colors of insulating silicone rubber materials, the colorant is preferably iron oxide with a particle size of 0.5 to 1.5 μm (e.g., 0.5 μm, 0.8 μm, 1.0 μm, 1.2 μm, 1.5 μm, etc.), to further improve the mechanical properties of the insulating silicone rubber material.

[0046] In order to prevent the hydrophilicity of the iron oxide surface from affecting the thermal conductivity of the insulating silicone rubber material, the surface of the iron oxide is preferably hydrophobically modified and can be purchased from a commercial source, such as Zhejiang Huayuan Pigment Co., Ltd., model F110.

[0047] In a second typical embodiment of the present application, a method for preparing an insulating silicone rubber material is also provided, which comprises: mixing, refining and vulcanizing methyl vinyl silicone rubber, white carbon black, a first aluminum hydroxide, a second aluminum hydroxide, a silane coupling agent, a vulcanizing agent, nano-montmorillonite, a vulcanizing agent, hydroxyl silicone oil and an optional colorant in sequence to obtain the insulating silicone rubber material.

[0048] The preparation method of the insulating silicone rubber material provided in the present application has a simple process and is operable, can be produced on a large scale, improves production efficiency and reduces preparation costs.

[0049] In order to further improve the mechanical properties of the insulating silicone rubber material, the vulcanization molding temperature is preferably 165-185° C., the pressure is 10-12 MPa, and the time is 10-14 minutes.

[0050] Typically, but not limitatively, the vulcanization molding temperature is 165°C, 170°C, 175°C, 180°C, 185°C, or a range consisting of any two values; the pressure is 10MPa, 10.5MPa, 11MPa, 11.5MPa, 12MPa, or a range consisting of any two values; the time is 10min, 11min, 12min, 13min, 14min, or a range consisting of any two values.

[0051] In some specific embodiments of the present application, the insulating silicone rubber material is prepared according to the following steps:

[0052] Step S1, placing various surface-untreated powders (white carbon black, first aluminum hydroxide, second aluminum hydroxide) in a vacuum drying oven and drying at 100-120° C. for 3-4 hours;

[0053] Step S2: Place the weighed methyl vinyl silicone rubber, nano-montmorillonite, the first aluminum hydroxide, and the second aluminum hydroxide into a kneader and knead thoroughly. The powder is gradually added in batches to allow the methyl vinyl silicone rubber and the powder to fully blend. After the powder addition is complete, mix for 0.5 to 1 hour. Then, add the iron oxide, nano-montmorillonite, and silane coupling agent into the kneader and evacuate the mixture for vacuum kneading. The vacuum degree is controlled at 0.05 to 0.25 MPa and the temperature is 130 to 160°C. Mix for 2 to 3 hours to obtain a rubber mix.

[0054] Step S3, rolling the mixed rubber on an open mill, adding a vulcanizing agent, thinning, and sheeting to obtain a sheet material, and then placing the sheet material on a flat vulcanizing press for vulcanization molding at 165-185° C. and a pressure of 10-12 MPa for 10-14 minutes to obtain the insulating silicone rubber material.

[0055] In a third typical embodiment of the present application, an insulating silicone rubber shed is further provided. The material of the insulating silicone rubber shed is the insulating silicone rubber material provided in the first typical embodiment.

[0056] The insulating silicone rubber shed material provided in this application is the same as the insulating silicone rubber material provided in the first exemplary embodiment described above. This material not only improves water absorption properties but also increases thermal conductivity, while also reducing polarization losses and abnormal heating in hot and humid environments. Furthermore, the insulating silicone rubber shed material provided in this application also possesses excellent mechanical properties and pollution resistance, offering broad application prospects.

[0057] In a fourth typical embodiment of the present application, a method for preparing the above-mentioned insulating silicone rubber shed is also provided, which comprises: placing the insulating silicone rubber material into a mold and performing hot pressing molding to obtain the insulating silicone rubber shed.

[0058] The preparation method of the insulating silicone rubber shed provided in the present application has a simple process and is suitable for large-scale production, thereby effectively reducing production costs.

[0059] In order to further improve the efficiency of hot pressing, the hot pressing temperature is preferably 170-190° C., the pressure is 10-15 MPa, and the time is 15-20 min.

[0060] Typically, but not limitatively, in the present application, the temperature of hot pressing is 170°C, 175°C, 180°C, 185°C, 190°C or a range consisting of any two values; the pressure is 10MP, 11MP, 12MP, 13MP, 14MP, 15MPa or a range consisting of any two values; and the time is 15min, 16min, 17min, 18min, 19min, 20min or a range consisting of any two values.

[0061] The beneficial effects of the present application will be further illustrated below with reference to examples and comparative examples.

[0062] Example 1

[0063] This embodiment provides an insulating silicone rubber shed, the materials of which, by weight, include 100 parts of methyl vinyl silicone rubber, 30 parts of fumed silica, 110 parts of aluminum hydroxide, 3 parts of a silane coupling agent, 5 parts of organically modified nano-montmorillonite, 2 parts of a vulcanizing agent, 4 parts of hydroxy silicone oil, and iron oxide with a particle size of 1 μm (the surface of which has been hydrophobically treated). The methyl vinyl silicone rubber includes a first silicone rubber (with a number average molecular weight of 650,000 and a vinyl content of 0.2%) and a second silicone rubber (with a number average molecular weight of 650,000 and a vinyl content of 3%). , and the mass ratio of the two is 1:1.8; aluminum hydroxide includes a first aluminum hydroxide with an average particle size of 1 μm and a second aluminum hydroxide with an average particle size of 5 μm, and the mass ratio of the two is 6:1; the silane coupling agent is KH550; the vulcanizing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; the hydroxyl content in the hydroxyl silicone oil is 4%; the iron oxide with a hydrophobic surface treatment is purchased from Zhejiang Huayuan Pigment Co., Ltd., model F110; the organically modified nano-montmorillonite is purchased from Zhejiang Fenghong New Materials Co., Ltd., model DK5.

[0064] The insulating silicone rubber shed is prepared according to the following steps:

[0065] (1) Place various surface-untreated powders (white carbon black, first aluminum hydroxide, and second aluminum hydroxide) in a vacuum drying oven and dry at 100-120°C for 3-4 hours;

[0066] (2) The weighed methyl vinyl silicone rubber, nano-montmorillonite, the first aluminum hydroxide and the second aluminum hydroxide are placed in a kneader and fully kneaded, and the powder is gradually added in batches to allow the methyl vinyl silicone rubber and the powder to be fully integrated. After the powder is added, mix for 1 hour, and then add the iron oxide, nano-montmorillonite and silane coupling agent into the kneader, evacuate and perform vacuum kneading, control the vacuum degree to 0.15MPa, the temperature to 145°C, and mix for 2.5 hours to obtain a rubber mixture;

[0067] (3) Roll the rubber mix on an open mill, add a vulcanizing agent, thin it, and form a sheet to obtain a sheet. The sheet is then placed on a flat vulcanizing press for vulcanization molding at 175°C and a pressure of 11 MPa for 12 minutes to obtain an insulating silicone rubber material.

[0068] (4) The insulating silicone rubber material is placed in a mold and hot-pressed for 20 minutes at 180° C. and a pressure of 13 MPa to obtain the insulating silicone rubber umbrella skirt.

[0069] Example 2

[0070] The difference between this embodiment and embodiment 1 is that the mass ratio of the first aluminum hydroxide to the second aluminum hydroxide is 5:1.

[0071] Example 3

[0072] The difference between this embodiment and embodiment 1 is that the mass ratio of the first aluminum hydroxide to the second aluminum hydroxide is 7:1.

[0073] Example 4

[0074] The difference between this embodiment and embodiment 1 is that the particle size of the first aluminum hydroxide is 0.5 μm, and the particle size of the second aluminum hydroxide is 4 μm.

[0075] Example 5

[0076] The difference between this embodiment and embodiment 1 is that the particle size of the first aluminum hydroxide is 1.5 μm, and the particle size of the second aluminum hydroxide is 6 μm.

[0077] Example 6

[0078] The difference between this embodiment and Example 1 is that, by mass, the amount of fumed silica is 40 parts, the total amount of aluminum hydroxide is 100 parts, the amount of silane coupling agent is 2 parts, the amount of nano-montmorillonite is 7 parts, the amount of vulcanizing agent is 1 part, the amount of hydroxy silicone oil is 5 parts, and the amount of iron oxide is 3 parts.

[0079] Example 7

[0080] The difference between this embodiment and Example 1 is that, by mass, the amount of fumed silica is 25 parts, the total amount of aluminum hydroxide is 120 parts, the amount of silane coupling agent is 4 parts, the amount of nano-montmorillonite is 3 parts, the amount of vulcanizing agent is 3 parts, the amount of hydroxy silicone oil is 3 parts, and the amount of iron oxide is 5 parts.

[0081] Example 8

[0082] The difference between this embodiment and Example 1 is that the number average molecular weight of the first silicone rubber is 600,000, the mass content of vinyl is 0.15%, the number average molecular weight of the second silicone rubber is 700,000, the mass content of vinyl is 2.5%, and the mass ratio of the first silicone rubber to the second silicone rubber is 1:1.5.

[0083] Example 9

[0084] The difference between this embodiment and embodiment 1 is that the number average molecular weight of the first silicone rubber is 700,000, the number average molecular weight of the second silicone rubber is 600,000, the mass content of vinyl is 3.5%, and the mass ratio of the first silicone rubber to the second silicone rubber is 1:2.

[0085] Example 10

[0086] The difference between this embodiment and embodiment 1 is that methyl vinyl silicone rubber is the first silicone rubber.

[0087] Example 11

[0088] The difference between this embodiment and embodiment 1 is that methyl vinyl silicone rubber is used as the second silicone rubber.

[0089] Example 12

[0090] The difference between this embodiment and embodiment 1 is that the mass ratio of the first silicone rubber to the second silicone rubber is 1:4.

[0091] Example 13

[0092] The difference between this embodiment and embodiment 1 is that the mass ratio of the first silicone rubber to the second silicone rubber is 4:1.

[0093] Comparative Example 1

[0094] The difference between this comparative example and Example 1 is that all the aluminum hydroxide is the first aluminum hydroxide.

[0095] Comparative Example 2

[0096] The difference between this comparative example and Example 1 is that all the aluminum hydroxide is the second aluminum hydroxide.

[0097] Comparative Example 3

[0098] The difference between this comparative example and Example 1 is that the mass ratio of the first aluminum hydroxide to the second aluminum hydroxide is 4:1.

[0099] Comparative Example 4

[0100] The difference between this comparative example and Example 1 is that the mass ratio of the first aluminum hydroxide to the second aluminum hydroxide is 8:1.

[0101] Comparative Example 5

[0102] The difference between this comparative example and Example 1 is that the amount of white carbon black used is 10 parts by mass, and the total amount of aluminum hydroxide used is 130 parts by mass.

[0103] Comparative Example 6

[0104] The difference between this comparative example and Example 1 is that the amount of white carbon black used is 55 parts by mass, and the total amount of aluminum hydroxide used is 85 parts by mass.

[0105] Test Example 1

[0106] The thermal conductivity, dielectric loss tangent, tensile strength of the insulating silicone rubber sheds provided in the above embodiments and comparative examples, as well as the thermal conductivity, dielectric loss tangent and tensile strength after wet heat aging treatment, are shown in Table 1 below.

[0107] Among them, the specific steps of (1) wet heat aging treatment are:

[0108] The surface of the silicone rubber sample with a length of 200 mm, a width of 200 mm, and a thickness of 1 mm was wiped clean with anhydrous ethanol and non-woven fabric, and then placed in a constant temperature digital display water bath for water boiling and heat aging test. The test temperature was set at 100 ° C. After boiling for 28 days, the sample was taken out for testing and the test data was recorded.

[0109] (2) The test method for thermal conductivity is:

[0110] The DRL-II heat flow thermal conductivity tester, manufactured by Xiangtan Xiangyi Instrument Co., Ltd., uses the steady-state heat flow method. Once the sample temperature reaches a stable 45°C, the temperature of four evenly distributed points on the upper and lower sides of the sample is measured. Based on the heat transfer area and thickness, the thermal conductivity of the sample is calculated. During the test, to ensure good contact between the sample and the test rod, thermal grease is evenly applied to the upper and lower surfaces of the sample. For this instrument, the sample used is a circular wafer with a diameter of 30 mm and a thickness of approximately 1 mm.

[0111] (3) The test method for dielectric loss tangent is:

[0112] The dielectric constant and dielectric loss tangent were tested using a NOVOCONTROL Concept 40 broadband dielectric spectrum analyzer according to GBT 1693-2007. HTV insulation test pieces with a diameter of 100 mm and a thickness of 1 mm were prepared. Method A was used for testing, with a test voltage of 1000 V and a power supply frequency of 50 Hz.

[0113] (4) The test method for tensile strength is:

[0114] A CMT6104 microcomputer-controlled electronic universal testing machine was used to prepare dumbbell-shaped specimens with a thickness of 2 mm and a tensile speed of 500 mm / min to test the tensile properties.

[0115] Table 1

[0116] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0117] The technical solution provided by this application utilizes a first aluminum hydroxide with a particle size of 0.5 to 1.5 μm and a second aluminum hydroxide with a particle size of 4 to 6 μm, which are combined as fillers. This effectively improves the water absorption and thermal conductivity of the insulating silicone rubber material provided by this application, thereby effectively reducing polarization loss and abnormal heating in hot and humid environments. Furthermore, the insulating silicone rubber material provided by this application exhibits excellent mechanical properties and pollution flashover resistance, and has broad application prospects.

[0118] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. An insulating silicone rubber material resistant to hot and humid environments, characterized in that: In terms of mass, the insulating silicone rubber material includes: 100 parts of methyl vinyl silicone rubber, 25-40 parts of white carbon black, 100-120 parts of aluminum hydroxide, 2-4 parts of silane coupling agent, 3-7 parts of nano-montmorillonite, 1-3 parts of vulcanizing agent and 3-5 parts of hydroxy silicone oil, wherein the aluminum hydroxide includes a first aluminum hydroxide and a second aluminum hydroxide, the particle size of the first aluminum hydroxide is 0.5-1.5 μm, the particle size of the second aluminum hydroxide is 4-6 μm, and the mass ratio of the two is 5-7:

1.

2. The insulating silicone rubber material according to claim 1, characterized in that: The methyl vinyl silicone rubber includes a first silicone rubber and a second silicone rubber, wherein the first silicone rubber has a number average molecular weight of 600,000 to 700,000 and a vinyl content of 0.15 to 0.20%, the second silicone rubber has a number average molecular weight of 600,000 to 700,000 and a vinyl content of 2.5 to 3.5%, and the mass ratio of the two is 1:1.5 to 2.

3. The insulating silicone rubber material according to claim 1, characterized in that: The white carbon black is fumed white carbon black with a specific surface area of ​​150 to 300 m 3 / g.

4. The insulating silicone rubber material according to claim 1, characterized in that: The silane coupling agent includes at least one of KH550, KH560 or KH570; And / or, the vulcanizing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

5. The insulating silicone rubber material according to claim 1, characterized in that: The nano-montmorillonite is organically modified nano-montmorillonite; And / or, the mass content of hydroxyl groups in the hydroxyl silicone oil is 3.5-4.5%.

6. The insulating silicone rubber material according to any one of claims 1 to 5, characterized in that: The insulating silicone rubber material further comprises 3 to 5 parts by mass of a colorant; preferably, the colorant is iron oxide with a particle size of 0.5 to 1.5 μm, and further preferably, the surface of the iron oxide is hydrophobically modified.

7. A method for preparing the insulating silicone rubber material according to any one of claims 1 to 6, characterized in that: The preparation method comprises: mixing, refining and vulcanizing the methyl vinyl silicone rubber, the white carbon black, the first aluminum hydroxide, the second aluminum hydroxide, the silane coupling agent, the vulcanizing agent, the nano-montmorillonite, the vulcanizing agent, the hydroxy silicone oil and the optional colorant in sequence to obtain the insulating silicone rubber material.

8. The preparation method according to claim 7, characterized in that: The vulcanization molding temperature is 165-185° C., the pressure is 10-12 MPa, and the time is 10-14 min.

9. An insulating silicone rubber shed, characterized in that: The material of the insulating silicone rubber shed is the insulating silicone rubber material according to any one of claims 1 to 6.

10. A method for preparing the insulating silicone rubber shed according to claim 9, characterized in that: The preparation method comprises: placing the insulating silicone rubber material into a mold for hot pressing to obtain the insulating silicone rubber shed; Preferably, the temperature of the hot pressing molding is 170-190° C., the pressure is 10-15 MPa, and the time is 15-20 min.

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