Composite silicone rubber material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of silicone rubber, in particular to a composite silicone rubber material and a preparation method and application thereof. According to the invention, two kinds of aluminum hydroxide with different particle sizes are adopted as inorganic flame-retardant fillers, and the aluminum hydroxide and the inorganic flame-retardant fillers cooperate with each other, so that the mechanical property and the flame-retardant property of the silicone rubber material are effectively improved, and melamine polyphosphate-silicon dioxide-ammonium polyphosphate composite particles are further added, so that the flame-retardant performance of the silicone rubber material is improved. The silicon rubber material and two kinds of aluminum hydroxide with different particle sizes play an organic-inorganic synergistic flame-retardant role, the arc ablation resistance of the silicon rubber material is greatly improved, meanwhile, the operation stability of the silicon rubber material under corona and local arc discharge is improved, the operation life of external insulation of electrical equipment such as a composite insulator is prolonged, and the service life of the silicon rubber material is prolonged. Therefore, the product has a better application prospect.

Description

Technical Field

[0001] The present disclosure relates to the technical field of silicone rubber, and particularly to a composite silicone rubber material, a preparation method thereof, and an application thereof. Background Art

[0002] Composite insulators with silicone rubber as the main material have the advantages of pollution flashover resistance, light weight, high mechanical strength, etc., and have become the mainstream choice for high-voltage transmission lines. However, during long-term operation, silicone rubber is prone to phenomena such as local arc and surface discharge when operating in harsh environments such as high humidity, pollution, heavy rain, and icing. Under the long-term action of the above discharge phenomena, the external insulation silicone rubber material of electrical equipment such as composite insulators is prone to a decrease in electrical and mechanical properties, and even aging failure, and in severe cases, it may even cause malignant accidents such as surface flashover and core rod breakage of composite insulators.

[0003] Currently, aluminum hydroxide (ATH) is generally used as a flame retardant in the field of composite insulators. However, pure ATH is an inorganic flame retardant filler, and it is easy to generate microscopic pores during the combination with organic silicone rubber, resulting in a decrease in the electrical and mechanical properties of the composite silicone rubber; at the same time, ATH is also prone to react with acidic substances in a humid environment, causing premature decomposition and precipitation of the filler, and the application effect is limited.

[0004] Therefore, how to provide a silicone rubber material with high electrical and mechanical properties and arc ablation resistance has become an urgent problem to be solved at present. Summary of the Invention

[0005] In order to solve the above technical problems, the present disclosure provides a composite silicone rubber material, a preparation method thereof, and an application thereof.

[0006] In a first aspect, the present disclosure provides a composite silicone rubber material, and the raw materials of the composite silicone rubber material include a mixed rubber and a vulcanizing agent;

[0007] By weight percentage, the mixed rubber includes the following components:

[0008]

[0009] In the melamine polyphosphate-silica-ammonium polyphosphate composite particles, the mass ratio of melamine polyphosphate, silica, and ammonium polyphosphate is (6-8):(1-3):1.

[0010] Among them, the content of the silicone rubber raw rubber can be 15wt%, 16wt%, 17wt%, 18wt%, 18wt% or 20wt%, etc.; the content of the reinforcing agent can be 30wt%, 32wt%, 34wt%, 36wt%, 38wt% or 40wt%, etc.; the content of the structure control agent can be 0.2wt%, 0.3wt%, 0.4wt% or 0.5wt%, etc.; the content of the lubricant can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt% or 0.5wt%, etc.; the content of the nano-aluminum hydroxide can be 20wt%, 22wt%, 24wt%, 26wt%, 28wt% or 30wt%; the content of the micro-aluminum hydroxide can be 10wt%, 11wt%, 12wt%, 13wt%, 14wt% or 15wt%, etc.; the content of the melamine polyphosphate-silica-ammonium polyphosphate composite particles can be 5wt%, 7wt%, 9wt%, 10wt%, 12wt% or 15wt%, but is not limited to the listed values, and other unlisted values within the above range are equally applicable.

[0011] In the melamine polyphosphate-silica-ammonium polyphosphate composite particles, the mass ratio of melamine polyphosphate, silica, and ammonium polyphosphate can be 6:3:1, 7:2:1, 8:3:2, 6:1:1 or 8:3:1, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0012] In the present disclosure, 1) silicone rubber raw rubber, as the base polymer of the silicone rubber material, is used to provide the main elasticity, high temperature resistance (-60°C - 300°C), and chemical stability of the silicone rubber. The main chain of the silicone rubber raw rubber is the -Si-O- bond, which endows the material with excellent weather resistance (resistance to ultraviolet rays and ozone) and hydrophobicity (contact angle > 90°). Its high hydrophobicity can reduce the formation of surface water films and lower the probability of leakage current paths; 2) reinforcing agents can significantly improve the physical properties of the rubber; 3) structure control agents are used to adjust the molecular weight and processing fluidity of the silicone rubber and prevent structuring; 4) aluminum hydroxide, as a halogen-free flame retardant, can inhibit combustion by endothermic decomposition, and the generated Al2O3 residue covers the surface to block the transfer of oxygen and heat. Moreover, in the present disclosure, by using two different particle sizes of aluminum hydroxide in combination, the mechanical properties and flame retardant properties of the silicone rubber material are greatly improved. Among them, micron-sized aluminum hydroxide (i.e., micron-sized ATH, heat decomposition temperature 200 - 250°C) decomposes when the silicone rubber is subjected to arc ablation, releasing a large amount of water vapor to form a fluffy carbon layer; nano-sized aluminum hydroxide (i.e., nano-sized ATH, decomposition temperature about 300 - 350°C) can fill the pores of the carbon layer and promote crosslinking to form a dense-fluffy composite carbon layer, preventing oxygen from entering and enhancing the flame retardant effect; 5) lubricants can reduce the viscosity of the rubber compound and improve the processing performance (such as extrusion and molding fluidity); 6) melamine polyphosphate - silica - ammonium polyphosphate composite particles (MPP-SiO2-APP composite particles): In the present disclosure, silica - ammonium polyphosphate is used to modify melamine polyphosphate, and the three undergo a crosslinking reaction to form a "phosphorus - nitrogen - silicon" series flame retardant. When applied, it can cooperate with two different particle sizes of aluminum hydroxide to form a double barrier of "carbonized layer - silicon oxide layer", with a thermal decomposition temperature of about 300°C, releasing NH3 and PO· free radicals to inhibit the flame chain reaction.

[0013] In addition, the present disclosure further improves the electrical properties, mechanical properties, and arc ablation resistance of the silicone rubber material by regulating the ratio of suitable raw materials. Among them, if the structure control agent is excessive, it will lead to a decrease in the mechanical properties of the silicone rubber material; if the lubricant is excessive, it will cause oiling on the surface of the silicone rubber material and a decrease in mechanical properties; if the micron-sized ATH is excessive, it will lead to an increase in the micro-porosity of the silicone rubber, and the mechanical and electrical properties of the silicone rubber material will decrease. If it is too little, the flame retardant and ablation resistance of the composite silicone rubber material will be insufficient; if the nano-sized ATH is excessive, it will cause agglomeration of the nano-sized ATH, an increase in the micro-porosity of the silicone rubber, and a decrease in the mechanical and electrical properties of the silicone rubber material; if it is too little, the micro-pores between the micron-sized ATH cannot be effectively filled, the porosity increases, and the mechanical and electrical properties of the silicone rubber material decrease; if the MPP-SiO2-APP composite particles are excessive, the cost of the silicone rubber material will soar from dozens of yuan per kilogram to hundreds of yuan per kilogram, making it difficult to promote and apply on a large scale. If it is too little, the flame retardant properties of the silicone rubber material will decrease.

[0014] For the MPP-SiO2-APP composite particles, the raw material ratio is also of great significance for improving the arc erosion resistance of the silicone rubber material. Too much or too little of any raw material will affect the efficacy of the composite particles and reduce the arc erosion resistance effect.

[0015] The following are the preferred technical solutions of the present disclosure, but not the limitations of the technical solutions provided by the present disclosure. Through the following technical solutions, the technical objectives and beneficial effects of the present disclosure can be better achieved and realized.

[0016] As a preferred technical solution of the present disclosure, the vulcanizing agent includes dicumyl peroxide.

[0017] Preferably, the weight of the vulcanizing agent is 1-3 wt% of the weight of the mixed rubber, such as 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt% or 3 wt%, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0018] As a preferred technical solution of the present disclosure, the silicone rubber raw rubber includes methyl vinyl silicone rubber.

[0019] Preferably, the molecular weight of the methyl vinyl silicone rubber is 500,000-800,000 Daltons, such as 500,000 Daltons, 600,000 Daltons, 700,000 Daltons or 800,000 Daltons, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0020] In the present disclosure, methyl vinyl silicone rubber is selected as the silicone rubber raw rubber, and the vinyl group (-CH=CH2) in its molecule can be cross-linked through peroxide or platinum catalysis to form a three-dimensional network structure.

[0021] Preferably, the reinforcing agent includes fumed silica.

[0022] Preferably, the specific surface area of the fumed silica is 200-300 m 2 / g, such as 200 m 2 / g, 220 m 2 / g, 240 m 2 / g, 260 m 2 / g, 280 m 2 / g or 300 m 2 / g, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0023] In the present disclosure, selecting fumed silica as the reinforcing agent can enhance the mechanical properties of the silicone rubber (the tensile strength is increased from 1-2 MPa to 8-12 MPa).

[0024] Preferably, the structured control agent includes hydroxy silicone oil.

[0025] Preferably, the viscosity of the hydroxy silicone oil at 25 °C is 15-40 mPa·s, such as 15 mPa·s, 20 mPa·s, 25 mPa·s, 30 mPa·s, 35 mPa·s or 40 mPa·s, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0026] In the present disclosure, the structured control agent is selected as hydroxy silicone oil, and the terminal hydroxyl groups (-OH) therein will condense with the hydroxyl groups on the surface of silica, reducing filler agglomeration.

[0027] Preferably, the lubricant includes dimethyl silicone oil.

[0028] Preferably, the dimethyl silicone oil includes linear polydimethylsiloxane.

[0029] Preferably, the molar mass of the dimethyl silicone oil is 1000-10000 g / mol, such as 1000 g / mol, 2000 g / mol, 3000 g / mol, 4000 g / mol, 5000 g / mol, 6000 g / mol, 7000 g / mol, 8000 g / mol, 9000 g / mol or 10000 g / mol, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0030] In the present disclosure, the lubricant is selected as low molecular weight linear polydimethylsiloxane, which has excellent compatibility with silicone rubber.

[0031] As a preferred technical solution of the present disclosure, the particle size of the nanoscale aluminum hydroxide is 100-500 nm, such as 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm or 500 nm, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0032] In the present disclosure, the particle size of the nanoscale aluminum hydroxide should not be too large, otherwise it will cause an increase in the micro-porosity of the composite silicone rubber, resulting in a decrease in mechanical and electrical properties.

[0033] Preferably, the particle size of the micron-scale aluminum hydroxide is 5-15 μm, such as 5 μm, 8 μm, 10 μm, 13 μm or 15 μm, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0034] In the present disclosure, the particle size of the micron-scale aluminum hydroxide should not be too small or too large. Being too small will cause a sharp increase in production costs, and being too large will cause an increase in the micro-porosity of the composite silicone rubber.

[0035] Preferably, the mass ratio of the nano aluminum hydroxide to the micro aluminum hydroxide is (1.8 - 2.2):1, such as 1.8:1, 1.9:1, 2.0:1, 2.1:1 or 2.2:1, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0036] In the present disclosure, by further limiting the mass ratio of the nano aluminum hydroxide to the micro aluminum hydroxide, the micro porosity of the composite silicone rubber can be reduced while not significantly increasing the product cost, and the flame retardancy, electrical properties and mechanical properties of the silicone rubber material can be improved.

[0037] Preferably, the nano aluminum hydroxide includes nano aluminum hydroxide modified with vinyl silane coupling agent (denoted as nano modified ATH).

[0038] Preferably, the micro aluminum hydroxide includes micro aluminum hydroxide modified with vinyl silane coupling agent (denoted as micro modified ATH).

[0039] In the present disclosure, the hydrophobicity of nano ATH and micro ATH is improved after being modified with vinyl silane coupling agent. During the application process, the mechanical properties and flame retardancy of the silicone rubber composite material can be further improved.

[0040] As a preferred technical solution of the present disclosure, the particle size of the melamine polyphosphate - silica - ammonium polyphosphate composite particle is 5 - 15 μm, such as 5 μm, 8 μm, 10 μm, 13 μm or 15 μm, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0041] As a preferred technical solution of the present disclosure, in the melamine polyphosphate - silica - ammonium polyphosphate composite particle, the particle size of the melamine polyphosphate is 5 - 10 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc.; the particle size of the silica is 20 - 50 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 50 nm, etc.; the particle size of the ammonium polyphosphate is 5 - 10 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc., but not limited to the listed values, and other unlisted values within the above range are equally applicable.

[0042] Preferably, in the melamine polyphosphate - silica - ammonium polyphosphate composite particle, the melamine polyphosphate includes melamine polyphosphate modified with amino silane coupling agent (denoted as modified MPP), and the silica includes silica modified with amino silane coupling agent (denoted as modified SiO2).

[0043] In the present disclosure, before forming the composite particles, melamine polyphosphate and silica are respectively modified with an amino-silane coupling agent, which can further improve their flame retardancy and hydrophobicity. Thus, after being mixed with ATH of different particle sizes, their synergistic effect can be more fully exerted, and the arc ablation resistance of the silicone rubber material can be improved.

[0044] In a second aspect, the present disclosure provides a method for preparing the composite silicone rubber material as described in the first aspect, and the preparation method includes the following steps:

[0045] (1) Mix melamine polyphosphate, silica, ammonium polyphosphate and water and carry out a cross-linking reaction, and then successively carry out spray drying and extrusion granulation to obtain melamine polyphosphate-silica-ammonium polyphosphate composite particles;

[0046] (2) Mix the raw silicone rubber, structure control agent, lubricant, nano-sized aluminum hydroxide, micro-sized aluminum hydroxide, melamine polyphosphate-silica-ammonium polyphosphate composite particles, reinforcing agent and vulcanizing agent, and then carry out vulcanization to obtain the composite silicone rubber material.

[0047] As a preferred technical solution of the present disclosure, the melamine polyphosphate and the silica in step (1) are independently modified with an amino-silane coupling agent, and the method for modification with an amino-silane coupling agent includes:

[0048] Mix the amino-silane coupling agent, ethanol aqueous solution and acetic acid to obtain a hydrolysis solution; mix the melamine polyphosphate or the silica with the hydrolysis solution and carry out a siloxane coupling reaction to obtain modified melamine polyphosphate or modified silica.

[0049] Preferably, before mixing the melamine polyphosphate or the silica with the hydrolysis solution, pre-drying is carried out first.

[0050] Preferably, the temperature of the pre-drying is 100 - 130 °C, such as 100 °C, 105 °C, 110 °C, 115 °C, 120 °C, 125 °C or 130 °C, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0051] Preferably, the mass of the amino-silane coupling agent is 0.5 - 3 wt% of the mass of the melamine polyphosphate or silica, such as 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt% or 3 wt%, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0052] Preferably, in the aqueous ethanol solution, the volume ratio of ethanol to water is (8.5 - 9.5):1, such as 8.5:1, 8.7:1, 9.0:1, 9.2:1, or 9.5:1, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0053] Preferably, the pH of the hydrolysis solution is 4 - 5, such as 4, 4.2, 4.4, 4.6, 4.8, or 5, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0054] Preferably, the extrusion granulation is carried out using a twin - screw extruder.

[0055] Inside the twin - screw extruder, there are a conveying zone (zone 1), a melting zone (zone 2), a kneading zone (zone 3), and an exhaust homogenization zone (zone 4). The temperature of the conveying zone is set to 140 - 170 °C, such as 140 °C, 150 °C, 160 °C, or 170 °C, etc.; the temperature of the melting zone is set to 170 - 190 °C, such as 170 °C, 180 °C, or 190 °C, etc.; the temperature of the kneading zone is set to 190 - 210 °C, such as 190 °C, 200 °C, or 210 °C, etc.; the temperature of the exhaust homogenization zone is set to 210 - 230 °C, such as 210 °C, 220 °C, or 230 °C, etc., but not limited to the listed values, and other unlisted values within the above range are equally applicable.

[0056] Preferably, the rotation speed of the twin - screw extruder is 150 - 250 r / min, such as 150 r / min, 180 r / min, 200 r / min, 220 r / min, or 250 r / min, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0057] As a preferred technical solution of the present disclosure, the nano - aluminum hydroxide and the micro - aluminum hydroxide in step (2) are independently modified by a vinyl silane coupling agent, and the method of modifying with a vinyl silane coupling agent includes:

[0058] Mix the nano - aluminum hydroxide or the micro - aluminum hydroxide with an aqueous solution of a vinyl silane coupling agent and carry out a siloxane coupling reaction to obtain nano - modified aluminum hydroxide or micro - modified aluminum hydroxide.

[0059] Preferably, the nano - aluminum hydroxide or the micro - aluminum hydroxide is pre - dried before being mixed with the aqueous solution of the vinyl silane coupling agent, and the temperature of the pre - drying is 100 - 120 °C, such as 100 °C, 105 °C, 110 °C, 115 °C, or 120 °C, etc., but not limited to the listed values, and other unlisted values within this range are equally applicable.

[0060] Preferably, the concentration of the vinyl silane coupling agent aqueous solution is 1-5 wt%, such as 1 wt%, 2 wt%, 3 wt%, 4 wt% or 5 wt%, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0061] Preferably, the vinyl silane coupling agent includes vinyltrimethoxysilane.

[0062] Preferably, the mass of the vinyl silane coupling agent is 0.8-3 wt% of the mass of the nano-sized aluminum hydroxide or the micro-sized aluminum hydroxide, such as 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt% or 3 wt%, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0063] As a preferred technical solution of the present disclosure, the more specific operation of step (2) includes:

[0064] Mix the raw silicone rubber, structure control agent, lubricant, nano-sized aluminum hydroxide, micro-sized aluminum hydroxide, and melamine polyphosphate-silica-ammonium polyphosphate composite particles to obtain a premixed rubber; then mix the premixed rubber, reinforcing agent, and vulcanizing agent, and perform vulcanization after mixing to obtain a composite silicone rubber material.

[0065] As a preferred technical solution of the present disclosure, the temperature of the vulcanization in step (2) is 120-150 °C, such as 120 °C, 130 °C, 140 °C or 150 °C, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0066] Preferably, the pressure of the vulcanization in step (2) is 0.8-1 MPa, such as 0.8 MPa, 0.9 MPa or 1 MPa, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0067] Preferably, the heating rate of the vulcanization in step (2) is 60-62 °C / min, such as 60 °C / min, 61 °C / min or 62 °C / min, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0068] Preferably, the time of the vulcanization in step (2) is 1-1.5 h, such as 1.0 h, 1.1 h, 1.2 h, 1.3 h, 1.4 h or 1.5 h, etc., but is not limited to the listed values, and other unlisted values within this range are equally applicable.

[0069] In the third aspect, the present disclosure provides a composite insulator, which is prepared by using the composite silicone rubber material described in the first aspect or the composite silicone rubber material prepared by the preparation method described in the second aspect.

[0070] The technical solutions provided by the embodiments of the present disclosure have the following advantages compared with the prior art:

[0071] The present disclosure uses two kinds of aluminum hydroxides with different particle sizes as inorganic flame retardant fillers. When used in combination, they effectively improve the mechanical properties and flame retardant properties of the silicone rubber material. Moreover, by further adding melamine polyphosphate-silica-ammonium polyphosphate composite particles, an "organic-inorganic" synergistic flame retardant effect is exerted with the two kinds of aluminum hydroxides with different particle sizes, greatly improving the arc erosion resistance of the silicone rubber material. The ablation depth is maintained below 1.2 mm. At the same time, the operation stability of the silicone rubber material under corona and partial arc discharge is improved, and the operation life of the external insulation of electrical equipment such as composite insulators is increased;

[0072] Furthermore, the present disclosure further limits the ratio of each raw material, and on this basis, further improves the arc erosion resistance of the silicone rubber material, so that the ablation depth is maintained below 1.0 mm, making the product have good application prospects. Detailed implementation manners

[0073] In order to more clearly understand the above-mentioned objects, features and advantages of the present disclosure, the solutions of the present disclosure will be further described below. It should be noted that, without conflict, the embodiments of the present disclosure and the features in the embodiments can be combined with each other.

[0074] Many specific details are set forth in the following description in order to fully understand the present disclosure, but the present disclosure may be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only a part of the embodiments of the present disclosure, rather than all the embodiments.

[0075] All reagents in the following examples and comparative examples were purchased commercially, and the specific parameters of some reagents are shown in Table 1.

[0076] Table 1

[0077]

[0078] Example 1

[0079] This example provides a composite silicone rubber material and a preparation method thereof. The raw materials of the composite silicone rubber material include a mixed rubber and a vulcanizing agent;

[0080] The vulcanizing agent is dicumyl peroxide;

[0081] The weight of the vulcanizing agent is 2 wt% of the weight of the mixed rubber;

[0082] In terms of weight percentage, the mixed rubber includes the following components:

[0083]

[0084] The particle size of the MPP-SiO2-APP composite particles is 8-12 μm, wherein the mass ratio of MPP, SiO2, and APP is 7:2:1;

[0085] The particle size of the MPP is 5-10 μm, the particle size of the SiO2 is 20-50 nm, and the particle size of the APP is 5-10 μm.

[0086] The preparation method includes the following steps:

[0087] (1) Mix MPP, SiO2, APP with water and carry out a cross-linking reaction, then perform spray drying, and then use a twin-screw extruder for extrusion granulation to obtain MPP-SiO2-APP composite particles;

[0088] Among them, the temperature of the conveying zone of the twin-screw extruder is set at 160 °C, the temperature of the melting zone is 180 °C, the temperature of the mixing and kneading zone is 200 °C, and the temperature of the exhaust and homogenization zone is 220 °C;

[0089] (2) Place methyl vinyl silicone rubber, hydroxy silicone oil, dimethyl silicone oil, nano-scale ATH, micro-scale ATH, and MPP-SiO2-APP composite particles in a roller machine, stir at a speed of 10 r / min for 1.2 h to form a premixed rubber, and let it stand for 18 h; then mix and stir the premixed rubber with fumed silica and dicumyl peroxide for 1.2 h and let it stand for 20 h, and place the uniformly mixed raw materials in a high-temperature vulcanizer for vulcanization. Set the heating rate at 61 °C / min, the vulcanization temperature at 130 °C, the vulcanization pressure at 0.9 MPa, and the vulcanization time at 1.2 h to obtain a composite silicone rubber material with a thickness of 5 mm.

[0090] Example 2

[0091] This example provides a composite silicone rubber material and its preparation method. The composite silicone rubber material refers to the composite silicone rubber material in Example 1, and the difference is only that:

[0092] The nano-scale ATH is nano-scale aluminum hydroxide modified with a vinyl coupling agent (denoted as nano-scale modified ATH);

[0093] The micro-scale ATH is micro-scale aluminum hydroxide modified with a vinyl coupling agent (denoted as micro-scale modified ATH);

[0094] In the MPP-SiO2-APP composite particles, MPP is melamine polyphosphate modified with an amino silane coupling agent (denoted as modified MPP), and SiO2 is silica modified with an amino silane coupling agent (denoted as modified SiO2);

[0095] The components of the mixed rubber are as follows:

[0096]

[0097] The preparation method refers to the preparation method in Example 1, with the only difference being that it further includes:

[0098] ① Modify nano-ATH and micro-ATH with vinyl silane coupling agent respectively, including:

[0099] Pre-dry nano-ATH or micro-ATH at 110 °C for 3 h to remove surface moisture;

[0100] Mix the pre-dried nano-ATH or micro-ATH with an aqueous solution of vinyltrimethoxysilane with a concentration of 3 wt%, stir and react at 60 °C for 2 h, and then successively filter, wash, and dry to obtain nano-modified ATH or micro-modified ATH;

[0101] Among them, the mass of vinyltrimethoxysilane is 2 wt% of the mass of nano-ATH or micro-ATH;

[0102] ② Modify MPP and SiO2 in the MPP-SiO2-APP composite particles with amino silane coupling agent respectively, including:

[0103] Pre-dry MPP or SiO2 at 120 °C for 3 h to remove surface moisture;

[0104] Mix KH-550, an ethanol aqueous solution (volume ratio of ethanol to water is 9:1), and acetic acid to obtain a hydrolysis solution with a pH of 4;

[0105] Then mix the pre-dried MPP or SiO2 with the hydrolysis solution, stir at 60 °C for 2 h at a rotation speed of 300 r / min to react, and then successively filter, wash, and vacuum dry to obtain modified MPP or modified SiO2;

[0106] Among them, the mass of KH-550 is 2 wt% of the mass of MPP or SiO2.

[0107] Example 3

[0108] This example provides a composite silicone rubber material and its preparation method. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being:

[0109] The mixed rubber includes the following components:

[0110]

[0111] In the modified MPP-modified SiO2-APP composite particles, the mass ratio of modified MPP, modified SiO2, and APP is 6:3:1.

[0112] Example 4

[0113] This example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, and the difference is only that:

[0114] The mixed rubber includes the following components:

[0115]

[0116]

[0117] In the modified MPP-modified SiO2-APP composite particles, the mass ratio of modified MPP, modified SiO2, and APP is 8:2:1.

[0118] Example 5

[0119] This example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, and the difference is only that: the content of nano-scale modified ATH is 28 wt%, the content of micro-scale modified ATH is 10 wt%, and the contents of the remaining components remain unchanged, so that the components of the mixed rubber are as follows:

[0120]

[0121] The preparation method refers to the preparation method in Example 2.

[0122] Comparative Example 1

[0123] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 1, and the difference is only that: all nano-scale ATH and MPP-SiO2-APP composite particles are replaced with micro-scale ATH, so that the components of the mixed rubber are as follows:

[0124]

[0125] The preparation method refers to the preparation method in Example 1, and the difference is only that: step (1) is not included; and all nano-scale ATH and MPP-SiO2-APP composite particles in step (2) are replaced with micro-scale ATH.

[0126] Comparative Example 2

[0127] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 1, with the only difference being that all of the MPP-SiO2-APP composite particles are replaced with MPP, such that the components of the mixed rubber are as follows:

[0128]

[0129] The preparation method refers to the preparation method in Example 1, with the only difference being that step (1) is not included; and all of the MPP-SiO2-APP composite particles in step (2) are replaced with MPP.

[0130] Comparative Example 3

[0131] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that all of the nano-scale modified ATH and the modified MPP-modified SiO2-APP composite particles are replaced with micro-scale modified ATH, such that the components of the mixed rubber are as follows:

[0132]

[0133] The preparation method refers to the preparation method in Example 2, with the only difference being that step (1) and step ② are not included; and all of the nano-scale modified ATH and the -modified MPP-modified SiO2-APP composite particles in step (2) are replaced with micro-scale modified ATH.

[0134] Comparative Example 4

[0135] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that all of the modified MPP-modified SiO2-APP composite particles are replaced with modified MPP, such that the components of the mixed rubber are as follows:

[0136]

[0137] The preparation method refers to the preparation method in Example 1, with the only difference being that step (1) is not included; and in step ②, only MPP is modified with an amino silane coupling agent; and all of the modified MPP-modified SiO2-APP composite particles in step (2) are replaced with modified MPP.

[0138] Comparative Example 5

[0139] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that the nano-scale modified ATH is completely replaced by micro-scale modified ATH, such that the components of the mixed rubber are as follows:

[0140]

[0141] The preparation method refers to the preparation method in Example 2, with the only difference being that the nano-scale modified ATH in step (2) is completely replaced by micro-scale modified ATH.

[0142] Comparative Example 6

[0143] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that the micro-scale modified ATH is completely replaced by nano-scale modified ATH, such that the components of the mixed rubber are as follows:

[0144]

[0145] The preparation method refers to the preparation method in Example 2, with the only difference being that the micro-scale modified ATH in step (2) is completely replaced by nano-scale modified ATH.

[0146] Comparative Example 7

[0147] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that the modified MPP-modified SiO2-APP composite particles are not added, and the reduced amount is added to the nano-scale modified ATH and micro-scale modified ATH in proportion, such that the components of the mixed rubber are as follows:

[0148]

[0149] The preparation method refers to the preparation method in Example 2, with the only difference being that the modified MPP-modified SiO2-APP composite particles are not added in step (2).

[0150] Comparative Example 8

[0151] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that the content of nano-scale modified ATH is 13 wt%, the content of micro-scale modified ATH is 25 wt%, and the contents of the remaining components remain unchanged, such that the components of the mixed rubber are as follows:

[0152]

[0153] The preparation method refers to the preparation method in Example 2.

[0154] Comparative Example 9

[0155] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that the content of nano-modified ATH is 32 wt%, the content of micro-modified ATH is 6 wt%, and the contents of the other components remain unchanged, such that the components of the mixed rubber are as follows:

[0156]

[0157] The preparation method refers to the preparation method in Example 2.

[0158] Comparative Example 10

[0159] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that the content of the modified MPP-modified SiO2-APP composite particles is 20 wt%, and the increased content is obtained by proportionally reducing the nano-modified ATH and the micro-modified ATH, such that the components of the mixed rubber are as follows:

[0160]

[0161] The preparation method refers to the preparation method in Example 2.

[0162] Comparative Example 11

[0163] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that the content of the modified MPP-modified SiO2-APP composite particles is 1 wt%, and the reduced content is proportionally increased to the nano-modified ATH and the micro-modified ATH, such that the components of the mixed rubber are as follows:

[0164]

[0165] Comparative Example 12

[0166] This comparative example provides a composite silicone rubber material and a preparation method thereof. The composite silicone rubber material refers to the composite silicone rubber material in Example 2, with the only difference being that in the modified MPP-modified SiO2-APP composite particles, the mass ratio of modified MPP, modified SiO2, and APP is 1:1:1.

[0167] Performance Test

[0168] 1. The composite silicone rubber materials obtained in Examples 1-5 and Comparative Examples 1-12 were tested according to GB / T 6553-2024 "Test Method for Evaluating Tracking and Erosion Resistance of Electrical Insulating Materials Used in Severe Environmental Conditions", and the ablation depth was measured. The results are shown in Table 2.

[0169] 2. The composite silicone rubber materials obtained in Examples 1-5 and Comparative Examples 1-12 were tested according to GB / T 1690-2010 "Test Method for Resistance of Vulcanized Rubber or Thermoplastic Rubber to Liquids", and the moisture content was measured. The results are shown in Table 2.

[0170] Table 2

[0171] Ablation depth / mm Water content Example 1 0.9 0.40％ Example 2 0.8 0.25％ Example 3 0.83 0.23％ Example 4 1.0 0.35％ Example 5 1.2 0.41％ Comparative Example 1 2.8 0.50％ Comparative Example 2 1.8 0.31％ Comparative Example 3 2.3 0.45％ Comparative Example 4 1.9 0.35％ Comparative Example 5 1.6 0.32％ Comparative Example 6 1.8 0.29％ Comparative Example 7 1.7 0.31％ Comparative Example 8 1.4 0.37％ Comparative Example 9 1.5 0.35％ Comparative Example 10 1.4 0.31％ Comparative Example 11 1.7 0.43％ Comparative Example 12 2.1 0.33％

[0172] As can be seen from Table 2, the composite silicone rubber materials provided in Examples 1-5 of the present disclosure use ATH with two different particle sizes as flame retardant fillers. When used in combination, the mechanical properties and flame retardant properties of the silicone rubber materials are effectively improved. Moreover, by further adding MPP-SiO2-APP composite particles, their synergistic effect with the two different particle sizes is exerted, significantly improving the arc ablation resistance of the silicone rubber materials. The ablation depth is maintained below 1.2 mm. At the same time, the operating stability of the silicone rubber materials under corona and partial arc discharge is improved, increasing the operating life of the external insulation of electrical equipment such as composite insulators. And, in Examples 1-4, by controlling the ratio of each raw material, the arc ablation resistance of the silicone rubber materials is further improved, and the ablation depth is maintained below 1.0 mm.

[0173] Compared with Example 1, in Comparative Example 1, only micron-sized ATH was added, and nano-sized ATH and MPP-SiO2-APP composite particles were not added (i.e., traditional silicone rubber material), resulting in poor arc ablation resistance, and the ablation depth reached 2.8 mm, more than twice that of Example 1.

[0174] Compared with Example 1, although two different particle sizes of ATH were used in combination in Comparative Example 2, MPP was not compounded, resulting in insufficient flame retardant performance of the organic matter modified additive MPP and a decrease in arc ablation resistance.

[0175] In Comparative Example 3, only micron-sized modified ATH was added, and nano-sized modified ATH and modified MPP-modified SiO2-APP composite particles were not added. Although the arc ablation resistance was slightly improved compared with Comparative Example 1, there was still an obvious gap compared with Example 2, and the ablation depth was close to 3 times that of Example 2.

[0176] Comparative Example 4 is similar to Comparative Example 2. Although two kinds of modified ATH with different particle sizes are used in combination, the modified MPP is not compounded, resulting in the failure of the organic modified additive MPP to exert sufficient flame retardant performance and a reduction in flame retardant performance.

[0177] Compared with Example 2, in Comparative Example 5 and Comparative Example 6, only micron-sized modified ATH or only nano-sized modified ATH is used in combination with the modified MPP-modified SiO2-APP composite particles, and the two kinds of modified ATH with different particle sizes cannot play a synergistic role, and a dense-porous composite carbon layer cannot be formed to enhance the flame retardant effect. Therefore, the arc erosion resistance is poor.

[0178] Compared with Example 2, in Comparative Example 7, only two kinds of modified ATH with different particle sizes are added, and the modified MPP-modified SiO2-APP composite particles are not added, and the "inorganic-organic" synergistic flame retardant effect cannot be exerted, resulting in poor arc erosion resistance.

[0179] Compared with Example 2, in Comparative Example 8, the addition amount of micron-sized modified ATH is too much, and the addition amount of nano-sized modified ATH is too little, resulting in an increase in the micro-porosity of the silicone rubber, and the ATH cannot be filled into the silicone rubber material uniformly and effectively, so it has an adverse effect on the arc erosion resistance of the silicone rubber material.

[0180] Compared with Example 2, in Comparative Example 9, the addition amount of nano-sized modified ATH is too much, and the addition amount of micron-sized modified ATH is too little, resulting in the agglomeration of nano-sized ATH, and the ATH still cannot be filled into the silicone rubber material uniformly and effectively, having an adverse effect on the arc erosion resistance of the silicone rubber material.

[0181] Compared with Example 2, in Comparative Example 10, the addition amount of the modified MPP-modified SiO2-APP composite particles is too much, and the addition amounts of micron-sized modified ATH and nano-sized modified ATH are too little, resulting in too high product cost and reduced flame retardant performance, which in turn affects the arc erosion resistance of the silicone rubber material.

[0182] Compared with Example 2, in Comparative Example 11, the addition amount of the modified MPP-modified SiO2-APP composite particles is too little, and the addition amounts of micron-sized modified ATH and nano-sized modified ATH are too much, resulting in an increase in micro-porosity, reduced flame retardant performance, increased moisture content, and reduced service life.

[0183] Compared with Example 2, in the modified MPP-modified SiO2-APP composite particles of Comparative Example 12, the addition amount of the modified MPP is too little, resulting in insufficient flame retardant performance of the compounded composite particles, and the synergistic effect with nano-sized modified ATH and micron-sized modified ATH cannot be exerted during its application process, thus resulting in poor arc erosion resistance of the silicone rubber material.

[0184] It should be noted that, in this document, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the said element.

[0185] The above are only specific embodiments of the present disclosure, enabling those skilled in the art to understand or implement the present disclosure. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments described herein, but rather will conform to the broadest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composite silicone rubber material, characterized in that, The raw materials of the composite silicone rubber material include a mixed rubber and a vulcanizing agent; In terms of weight percentage, the mixed rubber includes the following components: In the melamine polyphosphate-silica-ammonium polyphosphate composite particles, the mass ratio of melamine polyphosphate, silica, and ammonium polyphosphate is (6-8):(1-3):

1.

2. The composite silicone rubber material according to claim 1, wherein The vulcanizing agent includes dicumyl peroxide; The weight of the vulcanizing agent is 1-3 wt% of the weight of the mixed rubber.

3. The composite silicone rubber material according to claim 1 or 2, characterized in that The raw silicone rubber includes methyl vinyl silicone rubber; Preferably, the molecular weight of the methyl vinyl silicone rubber is 500,000-800,000 Daltons; Preferably, the reinforcing agent includes fumed silica; Preferably, the specific surface area of the fumed silica is 200 - 300 m 2 / g; Preferably, the structure controlling agent includes hydroxy silicone oil; Preferably, the viscosity of the hydroxy silicone oil at 25 °C is 15-40 mPa·s; Preferably, the lubricant includes dimethyl silicone oil; Preferably, the molar mass of the dimethyl silicone oil is 1000-10000 g / mol.

4. The composite silicone rubber material according to any one of claims 1-3, characterized in that, The particle size of the nano-aluminum hydroxide is 100-500 nm; Preferably, the particle size of the micro-aluminum hydroxide is 5-15 μm; Preferably, the mass ratio of the nano-aluminum hydroxide to the micro-aluminum hydroxide is (1.8-2.2):1; Preferably, the nano-aluminum hydroxide includes nano-aluminum hydroxide modified with vinyl silane coupling agent; Preferably, the micro-aluminum hydroxide includes micro-aluminum hydroxide modified with vinyl silane coupling agent.

5. The composite silicone rubber material according to any one of claims 1-4, characterized in that, The particle size of the melamine polyphosphate-silica-ammonium polyphosphate composite particles is 5-15 μm; Preferably, in the melamine polyphosphate-silica-ammonium polyphosphate composite particles, the particle size of the melamine polyphosphate is 5-10 μm, the particle size of the silica is 20-50 nm, and the particle size of the ammonium polyphosphate is 5-10 μm; Preferably, in the melamine polyphosphate-silica-ammonium polyphosphate composite particles, the melamine polyphosphate includes melamine polyphosphate modified with amino silane coupling agent, and the silica includes silica modified with amino silane coupling agent.

6. A method for preparing a composite silicone rubber material according to any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Mix melamine polyphosphate, silica, ammonium polyphosphate with water and carry out a cross-linking reaction, then successively carry out spray drying and extrusion granulation to obtain melamine polyphosphate-silica-ammonium polyphosphate composite particles; (2) Mix the raw silicone rubber, structure controlling agent, lubricant, nano-aluminum hydroxide, micro-aluminum hydroxide, melamine polyphosphate-silica-ammonium polyphosphate composite particles, reinforcing agent, and vulcanizing agent, and then carry out vulcanization to obtain the composite silicone rubber material.

7. The preparation method according to claim 6, characterized in that, In step (1), the melamine polyphosphate and the silica are independently modified with amino silane coupling agent respectively, and the method of modifying with amino silane coupling agent includes: Mix the amino silane coupling agent, ethanol aqueous solution, and acetic acid to obtain a hydrolysis solution; mix the melamine polyphosphate or the silica with the hydrolysis solution and carry out a siloxane coupling reaction to obtain modified melamine polyphosphate or modified silica; Preferably, the mass of the amino-silane coupling agent is 0.5-3 wt% of the mass of the melamine polyphosphate or silica; Preferably, the pH of the hydrolysis solution is 4-5.

8. The preparation method according to claim 6 or 7, characterized in that, In step (2), the nano-aluminum hydroxide and the micro-aluminum hydroxide are each independently modified with a vinyl-silane coupling agent, and the method for modifying with a vinyl-silane coupling agent includes: Mixing the nano-aluminum hydroxide or the micro-aluminum hydroxide with an aqueous solution of a vinyl-silane coupling agent and undergoing a siloxane coupling reaction to obtain nano-modified aluminum hydroxide or micro-modified aluminum hydroxide; Preferably, the concentration of the aqueous solution of the vinyl-silane coupling agent is 1-5 wt%; Preferably, the vinyl-silane coupling agent includes vinyltrimethoxysilane; Preferably, the mass of the vinyl-silane coupling agent is 0.8-3 wt% of the mass of the nano-aluminum hydroxide or the micro-aluminum hydroxide.

9. The preparation method according to any one of claims 6-8, characterized in that, The temperature of vulcanization in step (2) is 120-150 °C; Preferably, the pressure of vulcanization in step (2) is 0.8-1 MPa; Preferably, the heating rate of vulcanization in step (2) is 60-62 °C / min; Preferably, the time of vulcanization in step (2) is 1-1.5 h.

10. A composite insulator, characterized in that, The composite insulator is prepared from the composite silicone rubber material as described in any one of claims 1-5 or the composite silicone rubber material prepared by the preparation method as described in any one of claims 6-9.

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