Silica gel composite insulating blanket with insulation and fireproof functions and preparation method thereof

Abstract

The present application relates to the technical field of insulation blanket, in particular to a silica gel composite insulation blanket with insulation and fireproof functions and a preparation method thereof. The silica gel composite insulation blanket comprises a methyl vinyl silica gel flexible insulation base layer, a silane coupling agent interface modification layer and an intumescent flame-retardant fireproof and heat-insulating coating layer which are sequentially stacked. The insulation base layer provides excellent electrical insulation, flexibility and weather resistance. The interface modification layer significantly enhances the adhesion between the base layer and the functional coating layer through chemical bonding, solving the problem of easy peeling between layers. The intumescent flame-retardant fireproof and heat-insulating coating layer on the outermost layer can rapidly expand to form a dense and high-strength carbonized heat-insulating layer when encountering high temperature or open flame, effectively blocking the transfer of heat to the inside and isolating oxygen.

Description

Technical Field

[0001] This invention relates to the field of insulating blanket technology, and in particular to a silicone composite insulating blanket with insulating and fireproof functions and its preparation method. Background Technology

[0002] In the field of power equipment protection, insulating blankets are mainly used to insulate and isolate energized or de-energized equipment to prevent electric shock or short circuits. Existing insulating blankets are mainly divided into two categories: one is single-function insulating blankets, typically made of rubber, epoxy resin, or ordinary silicone, possessing basic insulation properties but lacking or having only very low fire resistance, easily igniting or melting when exposed to fire, and unable to provide protection in fire scenarios. The other category is a combined solution adopted to improve safety, which involves first laying an insulating blanket on the electrical equipment, and then covering it with an additional layer of fireproof blankets such as asbestos cloth or fiberglass cloth. The method of layering insulating blankets with fireproof blankets has problems such as cumbersome installation, bulky size, poor fit, and no firm bond between the insulating and fireproof blankets, making them prone to displacement and peeling, affecting the reliability and durability of protection. It also increases storage, carrying, and handling costs.

[0003] In addition, some high-end insulation materials improve their flame retardancy rating by adding flame retardants such as aluminum hydroxide, but this method often comes at the cost of sacrificing the material's mechanical properties (such as flexibility and tear resistance) and electrical properties, and the thermal insulation effect is limited.

[0004] It is evident that existing technologies still need improvement and enhancement. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide a silicone composite insulating blanket with insulation and fireproof functions and its preparation method, aiming to solve the technical problem that insulating blankets in the prior art lack fireproof performance.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first aspect of the present invention provides a silicone composite insulating blanket with insulating and fireproof functions, comprising a methyl vinyl silicone flexible insulating matrix layer, a silane coupling agent interface modification layer, and an intumescent flame-retardant, fireproof, and heat-insulating coating, which are stacked sequentially. The raw materials for preparing the methyl vinyl silicone flexible insulating substrate layer, by weight, include: 100 parts methyl vinyl silicone, 38-42 parts fumed silica, 4.5-5.5 parts hydroxyl silicone oil, 5-6 parts vinyltrimethoxysilane modified lithium niobate nanosheets, 2-4 parts vinyltrimethoxysilane modified glass microspheres, and 1.2-1.8 parts peroxide curing agent; The raw materials for preparing the intumescent flame-retardant and fire-resistant heat-insulating coating, by weight, include: 100 parts of resin with a solid content of 40% to 50%, 20 to 35 parts of flame retardant, 5 to 10 parts of aluminum hydroxide or magnesium hydroxide, 1 to 3 parts of nano-silica, 0.8 to 2.2 parts of dispersant, 0.12 to 0.8 parts of defoamer, and 0.12 to 0.8 parts of leveling agent; the flame retardant includes ammonium polyphosphate, pentaerythritol, and melamine in a weight ratio of (2.5 to 5):1:1.

[0007] The silicone composite insulating blanket with insulation and fireproof functions is provided, wherein the raw material for preparing the silane coupling agent interface modification layer is an aminosilane coupling agent or an epoxysilane coupling agent.

[0008] The silicone composite insulating blanket with insulation and fireproof functions, wherein the resin is water-based acrylic resin or water-based epoxy resin.

[0009] The silicone composite insulating blanket with insulation and fireproof functions is wherein the flame retardant is composed of ammonium polyphosphate, pentaerythritol and melamine in a mass ratio of 3:1:1.

[0010] The silicone composite insulating blanket with insulation and fireproof functions, wherein the peroxide curing agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0011] The silicone composite insulating blanket with insulating and fireproof functions, wherein the fumed silica has a specific surface area of ​​150-200 m². 2 / g.

[0012] A second aspect of the present invention provides a method for preparing a silicone composite insulating blanket, comprising the following steps: S01. Preparation of a flexible insulating matrix of methyl vinyl silicone; S02. Spray a silane coupling agent with a concentration of 1-5 wt% onto the surface of a methyl vinyl silicone flexible insulating substrate; preheat at 80-100°C for 5-15 minutes to allow the solvent to evaporate; then cure at 120-150°C for 20-40 minutes to form a silane coupling agent interface modification layer. S03. Add flame retardant, aluminum hydroxide or magnesium hydroxide, nano silica, dispersant, defoamer and leveling agent to resin, disperse at high speed and uniformly to form fireproof coating slurry; spray the fireproof coating slurry uniformly onto the silane coupling agent interface modification layer, preheat and level at 60-80℃ for 5-10 minutes after each layer is sprayed, the wet film thickness of one layer is 200-300μm, and then cure at 100-120℃ for 15-25 minutes; repeat the operation until the designed total thickness is reached; finally, perform final curing at 120-140℃ for 60-120 minutes to obtain the silicone composite insulation blanket as described above.

[0013] The method for preparing the silicone composite insulating blanket includes the following steps: First, plasticize the raw methyl vinyl silicone rubber for 2-3 minutes; then add fumed silica, hydroxyl silicone oil, vinyltrimethoxysilane-modified lithium niobate nanosheets, and vinyltrimethoxysilane-modified glass microspheres in batches, controlling the discharge temperature to ≤65℃; after uniform mixing, sheet out and let it cure at room temperature for 24 hours; after curing, re-mill on a two-roll mill, add peroxide vulcanizing agent, and make triangular bags to ensure uniform dispersion to obtain the compound; press vulcanize, and after vulcanization, obtain the methyl vinyl silicone flexible insulating matrix.

[0014] The method for preparing the silicone composite insulating blanket includes the following steps: placing the compounded rubber into a flat vulcanizing mold preheated to 160-170°C, applying a pressure of 12-18 MPa, and determining the vulcanization time according to the thickness; after vulcanization, the methyl vinyl silicone flexible insulating matrix is ​​obtained.

[0015] Beneficial Effects: This invention provides a silicone composite insulating blanket with insulating and fireproof functions. It consists of a methyl vinyl silicone flexible insulating matrix layer and an intumescent flame-retardant and fire-resistant heat-insulating coating, achieved through a silane coupling agent interface modification layer. The methyl vinyl silicone flexible insulating matrix layer provides basic electrical insulation properties, mechanical strength, flexibility, and flame retardancy. Combined with the intumescent flame-retardant and fire-resistant heat-insulating coating containing a composite intumescent flame-retardant system, this integrated product simultaneously meets the requirements of high-level insulation, efficient fireproofing, excellent heat insulation, and good flexibility. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a silicone composite insulating blanket with insulation and fireproof functions.

[0017] Explanation of key component symbols: 1-Methyl vinyl silicone flexible insulating substrate layer, 2-Silane coupling agent interface modification layer, 3-Intumescent flame retardant and heat insulation coating. Detailed Implementation

[0018] This invention provides a silicone composite insulating blanket with insulating and fire-retardant functions, and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention.

[0019] The first aspect of the present invention provides a silicone composite insulating blanket with insulating and fireproof functions, comprising a methyl vinyl silicone flexible insulating matrix layer, a silane coupling agent interface modification layer, and an intumescent flame-retardant, fireproof, and heat-insulating coating, which are stacked sequentially. The raw materials for preparing the methyl vinyl silicone flexible insulating substrate layer, by weight, include: 100 parts methyl vinyl silicone, 38-42 parts fumed silica, 4.5-5.5 parts hydroxyl silicone oil, 5-6 parts vinyltrimethoxysilane modified lithium niobate nanosheets, 2-4 parts vinyltrimethoxysilane modified glass microspheres, and 1.2-1.8 parts peroxide curing agent.

[0020] Methyl vinyl silicone exhibits excellent insulation properties, good resistance to high and low temperatures, good weather resistance, and good flexibility. Compared with phenyl silicone and fluorosilicone, methyl vinyl silicone is less expensive and easier to process. To ensure good vulcanization activity and flexibility, the vinyl content of the methyl vinyl silicone is 0.08% to 0.16%.

[0021] The vinyltrimethoxysilane-modified lithium niobate nanosheets and vinyltrimethoxysilane-modified glass microspheres, after being modified with vinyltrimethoxysilane, have an organic hydrophobic layer grafted onto the powder surface, reducing the surface free energy of the powder. During the mixing process, they are wetted and encapsulated by silicone rubber molecular chains, preventing the formation of micron-level agglomeration defects, thus avoiding micro-powder agglomeration that would affect the strength of the matrix layer. The modified lithium niobate nanosheets form numerous tortuous barrier channels within the rubber matrix. At low temperatures, this delays heat conduction inward and hinders the outward diffusion of pyrolysis combustible gases, reducing combustion supply. At medium temperatures, the glass microspheres (borosilicate glass microspheres) soften and melt, generating borosilicate liquid glass. Combined with the rigid inorganic framework constructed by the overlapping lithium niobate nanosheets, the borosilicate glass liquid phase formed after the glass microspheres soften and melt can flow and fill the gaps in the framework, forming a seamless, integrated ceramic barrier layer. In addition, the organic branched chain of vinyltrimethoxysilane decomposes into silicon dioxide at high temperature, which is further integrated into the composite ceramic system to further improve the density and high temperature thermal stability of the carbon layer. At the same time, the decomposition process can absorb a small amount of combustion heat, which, together with the core calcium borate system, forms a multiple endothermic flame retardant mechanism to synergistically enhance the flame retardant effect of the condensed phase.

[0022] Ordinary metal oxide fillers readily catalyze the thermal oxidative cracking of the silicon-oxygen backbone, accelerating substrate combustion. In contrast, lithium niobate, after being coated with vinylsilane to passivate surface active sites, not only does not support combustion but also captures a small number of combustion-active free radicals, assisting in gas-phase flame retardancy. Furthermore, lithium niobate exhibits good stability at high temperatures, helping to prevent the overall collapse of the fireproof structure.

[0023] The modification steps for vinyltrimethoxysilane-modified lithium niobate nanosheets and vinyltrimethoxysilane-modified glass microspheres are as follows: Lithium niobate nanosheets and glass microspheres are mixed. For every 100 parts by weight of the mixed powder, prepare 4 parts vinyltrimethoxysilane, 80 parts anhydrous ethanol, and 8 parts deionized water. Adjust the pH of the system to 4.0–4.5 with glacial acetic acid. Stir and hydrolyze the vinyltrimethoxysilane for 15 min to obtain the hydrolysate. Then, mix the hydrolysate with the mixed powder, and modify by high-speed stirring at 60℃ in a water bath for 2 h. Filter, vacuum dry at 80℃, and disperse to obtain a composite powder of vinyltrimethoxysilane-modified lithium niobate nanosheets and vinyltrimethoxysilane-modified glass microspheres. The modification of lithium niobate nanosheets and glass microspheres can also be carried out separately.

[0024] With the help of vinyltrimethoxysilane-modified lithium niobate nanosheets and vinyltrimethoxysilane-modified glass microspheres, the methyl vinyl silicone flexible insulating matrix layer has a certain flame retardancy. In combination with the use of an intumescent flame retardant and heat-insulating coating, it can form multiple flame retardant effects during combustion, thereby improving the flame retardancy.

[0025] Since the tensile strength of pure methyl vinyl silicone rubber raw rubber after vulcanization is only 0.3–0.5 MPa, which cannot meet the mechanical requirements, this solution also incorporates fumed silica for reinforcement. Fumed silica, with its extremely high specific surface area and abundant silanol groups, forms a three-dimensional network in the rubber compound. Through hydrogen bonding and physical entanglement, it can significantly improve tensile strength, tear strength, and abrasion resistance, while having minimal impact on electrical properties and low cost.

[0026] While fumed silica can improve the mechanical properties of raw rubber, its tendency to form hydrogen bonds with silica gel raw rubber molecules leads to gradual hardening and loss of plasticity during storage, a phenomenon known as "structuring." Therefore, this solution incorporates hydroxyl silicone oil as a structure control agent. The hydroxyl groups at the molecular ends of hydroxyl silicone oil preferentially react with the silanol groups on the surface of fumed silica, blocking active sites and effectively inhibiting the tendency of the rubber compound to structure, extending its shelf life, and ensuring the processing performance and storage stability of the compound. Simultaneously, hydroxyl silicone oil also improves the dispersibility of fumed silica, enhancing its reinforcing effect.

[0027] Peroxide vulcanizing agent is the core component of silicone crosslinking and curing. Under heating conditions, it decomposes to generate free radicals, which trigger free radical coupling reactions of active groups (such as vinyl and methyl) on the side chains of silicone molecules to form CC crosslinks. This transforms the linear methyl vinyl silicone molecular chains into a three-dimensional network structure, thereby changing silicone from a plastic compound into a vulcanized elastomer with high elasticity, high strength, heat resistance and excellent electrical insulation.

[0028] The raw materials for preparing the intumescent flame-retardant and fire-resistant heat-insulating coating, by weight, include: 100 parts of resin with a solid content of 40% to 50%, 20 to 35 parts of flame retardant, 5 to 10 parts of aluminum hydroxide or magnesium hydroxide, 1 to 3 parts of nano-silica, 0.8 to 2.2 parts of dispersant, 0.12 to 0.8 parts of defoamer, and 0.12 to 0.8 parts of leveling agent; the flame retardant includes ammonium polyphosphate, pentaerythritol, and melamine in a weight ratio of (2.5 to 5):1:1.

[0029] In the raw materials for preparing the intumescent flame-retardant and heat-insulating coating, the resin is used to provide the film-forming properties and matrix adhesion of the coating, and can react with the active matrix of the silane coupling agent interface modification layer to form a multilayer composite structure.

[0030] The flame retardant uses a compound system, in which ammonium polyphosphate serves as both an acid and gas source flame retardant, pentaerythritol as a carbon source flame retardant, and melamine as a gas source flame retardant. Ammonium polyphosphate undergoes thermal decomposition upon heating (200–280°C), gradually releasing bound water and breaking POP bonds to generate strong dehydrating inorganic acids such as polyphosphoric acid, metaphosphoric acid, and pyrophosphoric acid. Phosphoric acids are strong protic acids, stable at room temperature and activated at high temperatures, catalyzing the dehydration and carbonization of the hydroxyl groups in pentaerythritol polyol: removing intramolecular H and O atoms, which then detach from the organic skeleton in the form of water vapor, leaving the remaining carbon-rich skeleton cross-linked and solidified into a dense carbon layer. Without acid catalysis, pentaerythritol simply melts, flows, and decomposes upon heating, hardly forming carbon. Simultaneously, the melted polyphosphoric acid forms a glassy, ​​viscous liquid phase, wetting the pores of the carbon layer and improving its density and high-temperature stability. The phosphorus oxides generated from the decomposition of ammonium polyphosphate can coat the carbon layer, isolating oxygen and blocking heat transfer within the substrate; phosphorus free radicals in the gas phase can capture combustion free radicals and weakly inhibit chain combustion reactions. In addition, ammonium polyphosphate can continuously decompose at high temperatures to release ammonia, water vapor, and a small amount of gaseous phosphorus oxides. The gas can initially bubble and support the molten system, providing the basic gas volume for expansion and foaming.

[0031] Pentaerythritol undergoes intermolecular dehydration, etherification, and cross-linking reactions under acidic catalysis, transforming from a small-molecule alcohol into a fused-ring aromatic hard carbon framework, which forms the solid matrix of the expanded carbon layer. During dehydration, pentaerythritol generates a large amount of water vapor, which, together with the gas source components, causes the molten phosphoric acid-carbon precursor system to foam and expand, forming a porous honeycomb carbon layer. The entire melting, dehydration, and pyrolysis process can absorb a large amount of phase transition heat and reaction heat, thereby reducing the temperature of the material itself.

[0032] Melamine has a thermal decomposition temperature of 300–380℃, higher than that of ammonium polyphosphate and pentaerythritol, which is used to match the char layer solidification stage. Melamine can undergo significant endothermic sublimation and thermal decomposition, releasing inert, non-flammable gases such as NH3, N2, and CO2. When ammonium polyphosphate and pentaerythritol have formed a molten, viscous char precursor, the decomposition and gas release of melamine lifts and stretches the molten system, forming a thick and fluffy expanded char layer. Because the decomposition temperature lags behind the char formation reaction, premature foaming will not cause the char layer to crack or gas to escape. The inert gas formed by the decomposition of melamine can fill the micropores of the char layer, diluting the concentration of oxygen and combustible decomposition gases at the char layer interface, thus weakening the oxygen supply for combustion. The nitrogen-containing groups in melamine can also form ionic bonds with polyphosphate to generate a phosphorus-nitrogen hybrid char layer, improving the char layer's oxidation resistance and burn-resistance, making it less prone to oxidation and burn-through at high temperatures; while the nitrogen-containing free radicals in the gas phase can quench combustion-active free radicals, assisting in gas-phase flame retardancy.

[0033] The composite flame-retardant system employed in this invention functions sequentially across different temperature ranges, providing overall synergistic flame retardancy. At 200–280°C, ammonium polyphosphate decomposes first, releasing phosphoric acid, causing melamine to dehydrate and carbonize under acid catalysis, generating water vapor, and the system begins to melt and initially foam. At 280–380°C, melamine decomposes in large quantities, releasing inert gases, and the melt is fully foamed and expanded, forming a honeycomb carbon layer several times its original thickness. Above 400°C, the phosphorus-nitrogen composite carbon layer solidifies and vitrifies, firmly covering the substrate surface, thus providing a blocking effect and terminating combustion.

[0034] The aluminum hydroxide or magnesium hydroxide is used to assist in flame retardancy and smoke suppression.

[0035] The nano-silica is used to improve the coating strength and heat resistance.

[0036] The dispersant is used to prevent solid particles such as flame retardants from agglomerating in the slurry and to ensure uniform dispersion.

[0037] The defoamer is used to eliminate bubbles generated during stirring and spraying, preventing defects such as pinholes and craters from appearing in the coating.

[0038] The leveling agent is used to reduce the surface tension of the coating, so that the wet film after spraying can spread evenly and obtain a smooth and flat surface.

[0039] Preferably, the raw material for preparing the silane coupling agent interface modification layer is an aminosilane coupling agent or an epoxysilane coupling agent.

[0040] Preferably, the resin is a water-based acrylic resin or a water-based epoxy resin.

[0041] Preferably, the flame retardant is composed of ammonium polyphosphate, pentaerythritol and melamine in a mass ratio of 3:1:1.

[0042] Preferably, the peroxide sulfiding agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0043] Preferably, the specific surface area of ​​the fumed silica is 150–200 m² / g. 2 / g.

[0044] A second aspect of the present invention provides a method for preparing a silicone composite insulating blanket, comprising the following steps: S01. Preparation of a flexible insulating matrix of methyl vinyl silicone; S02. Spray a 1-5 wt% silane coupling agent onto the surface of a methyl vinyl silicone flexible insulating substrate; preheat at 80-100°C for 5-15 minutes to allow the solvent to evaporate and the silane coupling agent to be initially adsorbed; then cure at 120-150°C for 20-40 minutes to form a silane coupling agent interface modification layer; during this process, the alkoxy group at one end of the silane coupling agent undergoes a condensation reaction with the silanol group on the surface of the silicone substrate to form a strong Si-O-Si covalent bond; the amino or epoxy group at the other end faces outward, providing reactive active sites and high surface energy for subsequent coatings; S03. Add flame retardant, aluminum hydroxide or magnesium hydroxide, nano silica, dispersant, defoamer and leveling agent to resin, disperse at high speed and uniformly to form fireproof coating slurry; spray the fireproof coating slurry uniformly onto the silane coupling agent interface modification layer, preheat and level at 60-80℃ for 5-10 minutes after each layer is sprayed, the wet film thickness of one layer is 200-300μm, and then cure at 100-120℃ for 15-25 minutes; repeat the operation until the designed total thickness is reached; finally, perform final curing at 120-140℃ for 60-120 minutes to obtain the silicone composite insulation blanket as described above.

[0045] Preferably, the method for preparing the methyl vinyl silicone flexible insulating substrate includes the following steps: First, plasticize the raw methyl vinyl silicone rubber for 2-3 minutes; then add fumed silica, hydroxyl silicone oil, vinyltrimethoxysilane-modified lithium niobate nanosheets, and vinyltrimethoxysilane-modified glass microspheres in batches, controlling the discharge temperature to ≤65℃; after uniform mixing, sheet out and let it cure at room temperature for 24 hours; after curing, re-mill on a two-roll mill, add peroxide vulcanizing agent, and make triangular bags to ensure uniform dispersion to obtain the compound; press vulcanize, and after vulcanization, obtain the methyl vinyl silicone flexible insulating matrix.

[0046] Preferably, the pressure vulcanization step includes: placing the compounded rubber into a flat vulcanizing mold preheated to 160-170°C, applying a pressure of 12-18 MPa, and determining the vulcanization time according to the thickness; after vulcanization, the methyl vinyl silicone flexible insulating matrix is ​​obtained.

[0047] The present invention will be further illustrated by the following examples and comparative examples.

[0048] Example 1 A method for preparing a silicone composite insulating blanket includes the following steps: S01. Preparation of methyl vinyl silicone flexible insulating matrix: First, plasticize 100 parts of methyl vinyl silica gel (vinyl content 0.14%) raw rubber for 3 minutes; then add 40 parts of fumed silica (specific surface area 180m²) in batches. 2 The mixture consists of 5 parts hydroxyl silicone oil, 5 parts vinyltrimethoxysilane-modified lithium niobate nanosheets, and 3 parts vinyltrimethoxysilane-modified glass microspheres, with the discharge temperature controlled at ≤65℃. After uniform mixing, the mixture is sheeted and left to cure at room temperature for 24 hours. After curing, it is re-milled on a two-roll mill, and 1.5 parts peroxide vulcanizing agent (2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane) is added. Triangular packaging is used to ensure uniform dispersion. Pressure vulcanization is performed by placing the mixed rubber into a flat vulcanizing mold preheated to 165℃ and applying a pressure of 16 MPa. The vulcanization time is determined according to the thickness. After vulcanization, a 3mm thick methyl vinyl silicone flexible insulating matrix is ​​obtained. S02. Preparation of interface modification solution: Dissolve aminosilane coupling agent (KH-550) in a mixed solvent of ethanol and deionized water (volume ratio ethanol:water = 9:1), with a silane coupling agent concentration of 4 wt%; adjust the pH to 4 with acetic acid, and hydrolyze and age at room temperature for 1.5 hours to form a pre-hydrolyzed solution, i.e., interface modification solution; uniformly spray the interface modification solution onto the surface of the vulcanized, shaped, and cleaned methyl vinyl silicone flexible insulating substrate to ensure complete wetting; preheat at 90℃ for 8 minutes to allow the solvent to evaporate and the silane coupling agent to be initially adsorbed; then cure at 135℃ for 30 minutes; S03. Add 30 parts of flame retardant (composed of ammonium polyphosphate, pentaerythritol and melamine in a mass ratio of 3:1:1), 5 parts of aluminum hydroxide, 3 parts of nano silica, 1.2 parts of dispersant (DH-6190 water-based dispersant), 0.5 parts of defoamer (BYK-081 silicone defoamer), and 0.5 parts of leveling agent (BYK-358N silicone leveling agent) to 100 parts of resin (Nanhai Zhanying Chemical Materials' liquid water-based acrylic resin NN05), and disperse at high speed to form a fire-retardant coating slurry; uniformly spray the fire-retardant coating slurry onto the silane coupling agent interface modification layer, preheating and leveling at 70°C for 6 minutes after each layer is sprayed, with a wet film thickness of 300μm per layer, and then cure at 110°C for 20 minutes, repeating the operation until the thickness reaches 1.2mm; finally, perform final curing at 130°C for 100 minutes to obtain the silicone composite insulation blanket.

[0049] Example 2 A method for preparing a silicone composite insulating blanket differs from Example 1 in that the mass ratio of ammonium polyphosphate, pentaerythritol, and melamine in the intumescent flame-retardant and heat-insulating coating is 5:1:1, while the rest is the same as in Example 1.

[0050] Comparative Example 1 A method for preparing a silicone composite insulating blanket differs from Example 1 in that hydroxyl silicone oil is not added during the preparation of the methyl vinyl silicone flexible insulating matrix; otherwise, the method is the same as in Example 1.

[0051] Comparative Example 2 A method for preparing a silicone composite insulating blanket differs from Example 1 in that the methyl vinyl silicone flexible insulating matrix is ​​prepared without adding fumed silica, and instead uses an equal amount of calcium carbonate as filler; otherwise, it is the same as Example 1.

[0052] Comparative Example 3 A method for preparing a silicone composite insulating blanket, which differs from Example 1 in that vinyltrimethoxysilane-modified lithium niobate nanosheets are not added.

[0053] Comparative Example 4 A method for preparing a silicone composite insulating blanket differs from Example 1 in that the amount of vinyltrimethoxysilane-modified lithium niobate nanosheets added is 10 parts.

[0054] Comparative Example 5 A method for preparing a silicone composite insulating blanket, which differs from Example 1 in that vinyltrimethoxysilane modified glass microspheres are not added.

[0055] Comparative Example 6 A method for preparing a silicone composite insulating blanket differs from Example 1 in that the amount of vinyltrimethoxysilane modified glass microspheres added is 10 parts.

[0056] Comparative Example 7 A method for preparing a silicone composite insulating blanket differs from Example 1 in that the mass ratio of ammonium polyphosphate, pentaerythritol, and melamine in the intumescent flame-retardant and heat-insulating coating is 1:1:1, while the rest is the same as in Example 1.

[0057] Comparative Example 8 A method for preparing a silicone composite insulating blanket differs from Example 1 in that nano-silica is not added to the intumescent flame-retardant and heat-insulating coating, while the rest is the same as in Example 1.

[0058] Comparative Example 9 A method for preparing a silicone composite insulating blanket differs from Example 1 in that the amount of nano-silica added to the intumescent flame-retardant and heat-insulating coating is 10 parts.

[0059] The performance of the above embodiments and comparative examples was tested, and the results are shown in Table 1.

[0060] Table 1

[0061] As can be seen from the results in Table 1, considering multiple properties such as tensile strength, elongation at break, and volume resistivity, Examples 1 and 2 exhibit the best overall performance. Among them, Example 1 shows the best overall performance. Compared with Example 1, Example 2 has an adjusted ratio of flame retardant, resulting in a decrease in its power frequency withstand voltage, reflecting that the use of flame retardant in the flame-retardant and heat-insulating coating affects the overall insulation performance of the insulating blanket.

[0062] Compared with Example 1, Comparative Example 1 showed a significant decrease in tensile strength and elongation at break, reflecting that hydroxyl silicone oil helps to improve the strength of the methyl vinyl silicone flexible insulating matrix layer and can improve the volume resistivity.

[0063] Compared with Example 1, Comparative Example 2 showed a more significant decrease in tensile strength and elongation at break, reflecting that fumed silica played a key reinforcing role in the methyl vinyl silicone flexible insulating matrix. Although the addition of calcium carbonate can improve tensile strength, it is significantly less effective than that of fumed silica.

[0064] Compared with Example 1, Comparative Example 3 mainly shows a decrease in flame retardancy rating. The main reason is the lack of lithium niobate nanosheets, which leads to a decrease in the flame retardancy performance of the methyl vinyl silicone flexible insulating substrate layer. Although the intumescent flame retardant and heat-insulating coating can play a flame retardant role, the final flame retardant effect of this solution requires the methyl vinyl silicone flexible insulating substrate layer and the intumescent flame retardant and heat-insulating coating to work together.

[0065] Compared with Example 1, Comparative Example 4 showed a decrease in tensile strength, elongation at break, and volume resistivity. The main reason for this was that when there were too many modified lithium niobate nanosheets, it would lead to internal defects in the silicone, and the amount of silicone would be insufficient to encapsulate all the additives, thus resulting in poor crosslinking uniformity of the silicone.

[0066] Compared with Example 1, Comparative Example 5 mainly shows a decrease in flame retardancy rating. The main reason for this is the lack of vinyltrimethoxysilane modified glass microspheres. Glass microspheres can melt under medium temperature conditions to form a ceramic barrier layer, thereby playing a barrier role. In the absence of glass microspheres, the formation of the ceramic barrier layer is lacking, thus weakening the flame retardant effect.

[0067] Compared with Example 1, Comparative Example 6 mainly showed a decrease in tensile strength, elongation at break, and volume resistivity. This is because an excessive number of glass microspheres can lead to an imbalance in the ratio, resulting in internal defects in the silicone and thus a decrease in the uniformity of crosslinking of the silicone.

[0068] Compared with Example 1, Comparative Example 7 had a different mass ratio of ammonium polyphosphate, pentaerythritol, and melamine, resulting in a decrease in its flame retardancy rating and a significant reduction in its volume resistivity. This reflects that the change in the component ratio of the flame retardant not only affects the flame retardancy but also the volume resistivity.

[0069] Compared with Example 1, Comparative Example 8 showed a decrease in flame retardancy and flexibility, indicating that nano-silica plays a certain role in improving the flexibility and heat resistance of the coating.

[0070] Compared to Example 1, Comparative Example 9 showed a decrease in both elongation at break and power frequency withstand voltage, indicating that the amount of nano-silica used should not be excessive. Excessive use can easily lead to accumulation and a decrease in the resin content, resulting in a significant increase in system rigidity and a decrease in elongation at break. In addition, the surface of nano-SiO2 has a large number of Si-OH groups, which have strong hygroscopicity. Excessive addition may increase the overall moisture absorption of the coating and reduce the power frequency withstand voltage. The decrease in the strength of the coating itself is also one of the possible reasons for the decrease in power frequency withstand voltage.

[0071] Seven samples were prepared using the same formulation as in Example 1, and their electrical performance at 20kV / 1min was tested. The results are shown in Table 2.

[0072] Table 2

[0073] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of the present invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A silicone composite insulating blanket with insulating and fireproof functions, characterized in that, It includes a methyl vinyl silicone flexible insulating substrate layer, a silane coupling agent interface modification layer, and an intumescent flame-retardant and heat-insulating coating, which are stacked sequentially. The raw materials for preparing the methyl vinyl silicone flexible insulating substrate layer, by weight, include: 100 parts methyl vinyl silicone, 38-42 parts fumed silica, 4.5-5.5 parts hydroxyl silicone oil, 5-6 parts vinyltrimethoxysilane modified lithium niobate nanosheets, 2-4 parts vinyltrimethoxysilane modified glass microspheres, and 1.2-1.8 parts peroxide curing agent; The raw materials for preparing the intumescent flame-retardant and fire-resistant heat-insulating coating, by weight, include: 100 parts of resin with a solid content of 40% to 50%, 20 to 35 parts of flame retardant, 5 to 10 parts of aluminum hydroxide or magnesium hydroxide, 1 to 3 parts of nano-silica, 0.8 to 2.2 parts of dispersant, 0.12 to 0.8 parts of defoamer, and 0.12 to 0.8 parts of leveling agent; the flame retardant includes ammonium polyphosphate, pentaerythritol, and melamine in a weight ratio of (2.5 to 5):1:

1.

2. The silicone composite insulating blanket with insulating and fireproof functions according to claim 1, characterized in that, The raw materials for preparing the silane coupling agent interface modification layer are aminosilane coupling agents or epoxysilane coupling agents.

3. The silicone composite insulating blanket with insulating and fireproof functions according to claim 1, characterized in that, The resin is a water-based acrylic resin or a water-based epoxy resin.

4. The silicone composite insulating blanket with insulating and fireproof functions according to claim 1, characterized in that, The flame retardant is composed of ammonium polyphosphate, pentaerythritol and melamine in a mass ratio of 3:1:

1.

5. The silicone composite insulating blanket with insulating and fireproof functions according to claim 1, characterized in that, The peroxide sulfiding agent is 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

6. The silicone composite insulating blanket with insulating and fireproof functions according to claim 1, characterized in that, The specific surface area of ​​the fumed silica is 150–200 m². 2 / g.

7. A method for preparing a silicone composite insulating blanket, characterized in that, Includes the following steps: S01. Preparation of a flexible insulating matrix of methyl vinyl silicone; S02. Spray a silane coupling agent with a concentration of 1-5 wt% onto the surface of a methyl vinyl silicone flexible insulating substrate; preheat at 80-100°C for 5-15 minutes to allow the solvent to evaporate; then cure at 120-150°C for 20-40 minutes to form a silane coupling agent interface modification layer. S03. Add flame retardant, aluminum hydroxide or magnesium hydroxide, nano silica, dispersant, defoamer and leveling agent to resin, disperse at high speed and uniformly to form fireproof coating slurry; spray the fireproof coating slurry uniformly onto the silane coupling agent interface modification layer, preheat and level at 60-80°C for 5-10 minutes after each layer is sprayed, the wet film thickness of one layer is 200-300μm, and then cure at 100-120°C for 15-25 minutes; repeat the operation until the designed total thickness is reached; finally, perform final curing at 120-140°C for 60-120 minutes to obtain the silicone composite insulation blanket according to any one of claims 1-6.

8. The method for preparing the silicone composite insulating blanket according to claim 7, characterized in that, The preparation method of the methyl vinyl silicone flexible insulating matrix includes the following steps: First, plasticize the raw methyl vinyl silicone rubber for 2-3 minutes; then add fumed silica, hydroxyl silicone oil, vinyltrimethoxysilane-modified lithium niobate nanosheets, and vinyltrimethoxysilane-modified glass microspheres in batches, controlling the discharge temperature to ≤65℃; after uniform mixing, sheet out and let it cure at room temperature for 24 hours; after curing, re-mill on a two-roll mill, add peroxide vulcanizing agent, and make triangular bags to ensure uniform dispersion to obtain the compound; press vulcanize, and after vulcanization, obtain the methyl vinyl silicone flexible insulating matrix.

9. The method for preparing the silicone composite insulating blanket according to claim 8, characterized in that, The pressure vulcanization step includes: placing the compounded rubber into a flat vulcanizing mold preheated to 160-170°C, applying a pressure of 12-18 MPa, and determining the vulcanization time according to the thickness; after vulcanization, the methyl vinyl silicone flexible insulating matrix is ​​obtained.

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