Silica aerogel thermal insulation coating and preparation method and application thereof

Abstract

The application relates to the field of coatings, and discloses a silica aerogel heat insulation coating and a preparation method and application thereof. The silica aerogel heat insulation coating comprises 40-70 parts of an aerogel slurry, 30-45 parts of a resin color paste and 4-8 parts of a solvent; the aerogel slurry comprises 3-10 parts of normal-pressure silica aerogel, 0.5-1 part of a silane coupling agent, 2-5 parts of a surfactant, 70-90 parts of water and 60-85 parts of anhydrous ethanol; the normal-pressure silica aerogel comprises 10-25 parts of tetraethoxysilane, 2-8 parts of octyltrimethoxysilane, 20-30 parts of n-heptane, 40-60 parts of an anhydrous ethanol-isopropanol mixed solution, 1-3 parts of a catalyst and 0.1-0.4 parts of polyethylene glycol and 7-15 parts of water; and the resin color paste comprises 50-80 parts of an organic silicon resin, 40-60 parts of a pigment and filler and 10-15 parts of an elastomer component. The coating takes the aerogel slurry as a core heat insulation component, is matched with the resin color paste containing the elastomer component, realizes uniform dispersion of the aerogel by controlling a process and a raw material ratio, and has low thermal conductivity, high adhesion and high coating stability.

Description

Technical Field

[0001] This invention relates to the field of coatings, and more particularly to a silica aerogel heat-insulating coating, its preparation method, and its application. Background Technology

[0002] With the promotion of mandatory standards for ultra-low energy consumption buildings, traditional insulation materials (rock wool, EPS boards) have drawbacks such as high thermal conductivity and poor fire resistance. Furthermore, traditional materials are bulky, prone to detachment, and occupy usable floor space, creating a demand for lightweight, efficient, and safe insulation materials. Current thermal insulation coatings can effectively reduce heat exchange and achieve efficient energy utilization, and are widely used in building energy conservation, industrial production, and equipment protection. They often use hollow glass microspheres and expanded perlite as insulation fillers. Although the cost is relatively low, they still suffer from high thermal conductivity (typically >0.03 W / (m·K)), limited insulation effect, and the coating is prone to cracking and detachment due to uneven filler dispersion, resulting in poor long-term stability.

[0003] Silica aerogel, as a super thermal insulation material, breaks through the limitations of traditional materials in principle due to its nanoporous structure. Its nanopore size is smaller than the mean free path of air molecules (68nm), which can completely suppress gas convection. Moreover, the framework is also composed of nanoscale silica particles, resulting in a long solid-phase heat conduction path and a thermal conductivity that is half that of static air and 1 / 3 to 1 / 4 that of traditional materials. At the same time, its low density reduces the burden on the substrate, and a coating thickness of 3-5mm can achieve the thermal insulation effect of 10-20mm of traditional materials.

[0004] Despite the significant advantages of silica aerogel thermal insulation coatings, several challenges remain. For instance, the preparation of silica aerogels is expensive, requiring supercritical CO2 drying for molding, resulting in costly equipment, high energy consumption, and limited large-scale production. For example, a silica aerogel material developed by the Haiying Aerospace Materials Research Institute, after sol-gel processing, is dried at 8-16 MPa, 40-80℃, and a CO2 flow rate of 100-1000 L / h. This aerogel is highly sensitive to process parameters, limiting production to small quantities and hindering large-scale coating applications. Furthermore, the high hydroxyl content and poor hydrophobicity of silica aerogels lead to poor compatibility with resin matrices, causing agglomeration and uneven dispersion in coatings, thus failing to fully realize their thermal insulation properties. For example, patent CN110527396B discloses a flexible modified aerogel thermal insulation coating and its preparation method. It involves mixing a thickening solution and an aqueous resin, then directly adding aerogel powder, and then adding reinforcing fibers to prepare a creamy coating. In this high-viscosity resin mixture, the aerogel powder is difficult to disperse evenly and tends to agglomerate during stirring, resulting in a significant reduction in the thermal insulation effect.

[0005] Furthermore, existing processes for preparing aerogel-containing thermal insulation coatings suffer from prominent issues such as incomplete aerogel modification, uncontrolled pigment grinding fineness, and unstable coating viscosity. Some processes require complex equipment or multiple adjustments, making it difficult to meet the demands of large-scale production. Therefore, developing a silica aerogel thermal insulation coating that exhibits uniform aerogel dispersion, excellent thermal insulation performance, good coating stability, and simple preparation has become an urgent problem for the industry. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a silica aerogel thermal insulation coating, its preparation method, and its application. This coating uses aerogel slurry as the core thermal insulation component, combined with a resin colorant containing elastomer components. By precisely controlling the preparation process and the proportions of each raw material in the coating, uniform dispersion of the aerogel is achieved. It possesses low thermal conductivity, high adhesion, high coating stability, and good workability, and the preparation process is simple and easy for industrial production.

[0007] The specific technical solution of this invention is as follows: First, a silica aerogel heat insulation coating comprises the following raw materials in parts by weight: 40-70 parts aerogel slurry, 30-45 parts resin pigment, 0.5-3 parts spraying additive, and 4-8 parts solvent.

[0008] In this invention, the aerogel slurry serves as the core thermal insulation structure of the coating. Its numerous porous structures significantly reduce heat conduction, while its extremely low density reduces the load on the substrate. After uniform dispersion, it forms a stable microstructure, enhancing the mechanical strength and structural integrity of the dried coating and preventing cracking. The resin pigment, acting as a film-forming and coloring matrix, not only provides excellent weather resistance and substrate adhesion but also imparts superior hiding power and color, while further enhancing the thermal insulation effect. Additives optimize the grinding and dispersion efficiency of the pigment, preventing pigment and filler agglomeration. Spraying aids improve the coating's spraying effect, resulting in a smooth and even coating.

[0009] The aerogel slurry comprises the following raw materials in parts by weight: 3-10 parts of atmospheric pressure silica aerogel, 0.5-1 part of silane coupling agent, 2-5 parts of surfactant, 70-90 parts of water, 60-85 parts of anhydrous ethanol, and pH adjuster.

[0010] The atmospheric pressure silica aerogel comprises the following raw materials in parts by weight: 10-25 parts tetraethoxysilane, 2-8 parts octyltrimethoxysilane, 20-30 parts n-heptane, 40-60 parts anhydrous ethanol-isopropanol mixture, 1-3 parts catalyst, 0.1-0.4 parts polyethylene glycol, and 7-15 parts water.

[0011] The resin color paste comprises the following raw materials in parts by weight: 50-80 parts of silicone resin, 40-60 parts of pigments and fillers, 10-15 parts of elastomer components, and 1-6 parts of additives.

[0012] The elastomer component is selected from hydroxyl-terminated polydimethylsiloxane elastomer (PMX-0156) and polyurethane modified silane prepolymer (XP2678).

[0013] This invention adds an appropriate amount of elastomer components to the coating, which can reduce the brittleness of the coating after it is formed, thus reducing the risk of cracking and peeling. Furthermore, this invention has found that not all types of elastomer components can achieve ideal results in the coating system of this invention. For example, pure polyurethane elastomers and polyolefin elastomers are not effective because they are prone to resin system delamination or reduce the weather resistance of the coating, failing to balance toughness and the stability of the heat-insulating coating. Ultimately, this invention selects hydroxyl-terminated polydimethylsiloxane elastomer (PMX-0156) and polyurethane-modified silane prepolymer (XP2678), both of which have good compatibility with the coating system of this invention and can form an ideal elastic buffer network.

[0014] Preferably, the additives include wetting and dispersing agents and leveling agents. The spraying additives include defoamers and film-forming agents. More preferably, the wetting and dispersing agents include one or more of BYK-307, BYK-371, and TEGO Dispers 610; the leveling agents include one or more of BYK-333, BYK-306, and TEGO Glide 410; the defoamers include one or more of BYK-052, BYK-077, and TEGO Airex 9100; and the film-forming agents include one or more of alcohol ester dodecyl, alcohol ester hexadecyl, and propyl benzoate.

[0015] Among them, wetting and dispersing agents are used to improve the dispersion stability of aerogels and pigments / fillers; leveling agents are used to ensure a smooth coating surface and avoid sagging or pinholes; defoamers are used to eliminate air bubbles generated during coating preparation and application, ensuring coating density; and film-forming agents are used to lower the film-forming temperature of silicone resins and improve coating integrity. Solvents are used to adjust the viscosity of the coating, adapt it to brushing, spraying, and other application methods, and also assist in the dissolution of resins and additives, ensuring the stability of the coating system.

[0016] Preferably, the solvent includes one or more of toluene, xylene, ethylene glycol butyl ether, and methyl isobutyl ketone.

[0017] The solvents mentioned above exhibit excellent compatibility with silicone resins and have a moderate evaporation rate.

[0018] Preferably, the silane coupling agent is KH-560.

[0019] Choosing the above-mentioned silane coupling agents can effectively improve the dispersibility of aerogels and inhibit their aggregation after modification.

[0020] Preferably, the surfactant is Tween-80.

[0021] The above-mentioned surfactants can be selected to address the problem of hydrophobic modification of aerogels agglomeration in water and improve the stability of the slurry.

[0022] Preferably, the pH adjuster is a 45-55 wt% formic acid solution.

[0023] Choosing the pH adjuster mentioned above is more effective in promoting the hydrolysis of silane coupling agents.

[0024] Preferably, the catalyst comprises a 5-15 wt% hydrochloric acid solution and a 30-40 wt% ammonia solution.

[0025] Choosing the catalysts mentioned above allows for better control of the sol-gel reaction rate.

[0026] Preferably, the pigments and fillers include one or more of ATO powder, hollow glass microspheres, and nano-TiO2.

[0027] Choosing the pigments and fillers mentioned above can further enhance the heat insulation effect of the coating.

[0028] Secondly, a method for preparing a silica aerogel heat-insulating coating includes: 1) Preparation of silica aerogel by atmospheric pressure method: Tetraethoxysilane and octyltrimethoxysilane were mixed and then anhydrous ethanol-isopropanol mixture was added and stirred evenly. Water and part of the catalyst were added and stirred to obtain a transparent silica sol system. Heptane and polyethylene glycol were added and stirred. Then, part of the catalyst was added and stirred again. After standing, silica gel was obtained. The silica gel was aged. After aging, it was first dried at 30-35℃ for 6-8h, then heated to 50-55℃ for 8-10h, and finally heated to 70-75℃ for 6-10h to obtain silica aerogel by atmospheric pressure method.

[0029] The method described above for preparing silica aerogel is low-cost, requiring only conventional drying ovens and reaction vessels, eliminating the need for high-pressure equipment for supercritical drying. This significantly reduces costs and eliminates cumbersome steps such as solvent replacement and high-pressure temperature control, thus shortening the production cycle. The ambient pressure environment eliminates the risk of high-pressure explosions, and VOC emissions are far lower than those of supercritical processes.

[0030] 2) Preparation of aerogel slurry: Silane coupling agent, water, anhydrous ethanol, and pH adjuster are mixed and stirred to fully hydrolyze the silane coupling agent to obtain a hydrolysate; the silica aerogel produced by atmospheric pressure method is ground into aerogel powder, sieved, mixed with anhydrous ethanol, stirred at low temperature, and the hydrolysate is added dropwise. After reaction, the mixture is filtered, washed, and dried to obtain modified aerogel powder; the modified aerogel powder, water, and surfactant are mixed and stirred to obtain aerogel slurry.

[0031] In the above steps, the siloxane bonds of the silane coupling agent are first hydrolyzed to generate silanols, providing active sites for subsequent modification. These silanols are then added dropwise to a suspension of silica aerogel powder dispersed in anhydrous ethanol under normal pressure. The hydroxyl groups of the silanols undergo dehydration condensation with the hydroxyl groups on the aerogel surface, thus achieving grafting and completing the modification. The silica aerogel modified with the silane coupling agent can be more uniformly dispersed in the slurry system, effectively preventing slurry aggregation and stratification.

[0032] 3) Preparation of resin color paste: Mix organosilicon resin, pigments, fillers, elastomer components and additives, ball mill, filter, and obtain resin color paste.

[0033] This invention reveals that the timing of adding the elastomer component is crucial. If it is added as an additive in step 4), it will not be able to fully grind and blend with the resin pigment, resulting in the formation of localized agglomerated particles. This significantly reduces the uniformity of dispersion in the coating system, leading to a noticeable grainy texture in the coating. Furthermore, because it cannot form a continuous elastic network, it cannot provide sufficient cushioning during bending, thus slightly reducing crack resistance. At the same time, the agglomerated particles will also damage the original intact thermal insulation structure, further reducing the thermal insulation performance of the coating. Therefore, all performance characteristics are significantly reduced.

[0034] 4) Preparation of silica aerogel thermal insulation coating: The aerogel slurry, resin pigment and spraying additive are mixed and stirred evenly, and the viscosity of the coating is adjusted with solvent to obtain silica aerogel thermal insulation coating.

[0035] The key to the preparation method of the present invention is that, through multiple treatments such as hydrolysis modification of silane coupling agent, wet dispersion of surfactant and grinding and sieving of silica aerogel under normal pressure, the problem of silica aerogel agglomeration can be completely solved, ensuring its uniform dispersion in coatings.

[0036] Preferably, in step 1), the stirring speed is 1100-1500 rpm and the aging temperature is 30-50℃.

[0037] Preferably, in step 2): the first mixing and stirring time is 0.5-2 hours; the sieving is done through a 400-600 mesh sieve; the reaction temperature is 40-70°C and the time is 0.5-1 hours; the washing uses anhydrous ethanol; the second mixing and stirring speed is 250-350 rpm and the time is 0.5-1 hours.

[0038] Preferably, in step 3): the mass ratio of grinding balls to raw materials during ball milling is 1:0.8-1.2; the rotation speed of the ball mill is 400-600 rpm, and the time is 3-7 h; the fineness of the color paste is below 30 μm.

[0039] Optimizing the ratio of grinding beads to raw materials and the grinding fineness can ensure the dispersion stability of resin pigments and the hiding power of coatings.

[0040] Preferably, in step 4): the stirring speed is 500-800 rpm; the viscosity of the coating is 7000-11000 mPa·s.

[0041] Precise control of stirring speed and viscosity range can balance the stability of coating system and application adaptability. The entire process requires no special equipment, the operation procedure is standardized, and it can be directly used for large-scale production.

[0042] Finally, the application of the aforementioned silica aerogel thermal insulation coating in the preparation of thermal insulation coatings includes: applying the coating to the surface of a substrate, heating and drying it to obtain a silica aerogel thermal insulation coating.

[0043] Preferably, the drying temperature is 150-250℃ and the time is 5-15 minutes.

[0044] Compared with the prior art, the beneficial effects of the present invention are: (1) By modifying silica aerogel powder, this invention can ensure that it is evenly dispersed in the coating, which solves the disadvantages of easy agglomeration and difficult processing, thus greatly extending the storage time of the coating, improving the heat insulation performance of the coating, and making the cured coating smoother.

[0045] (2) The present invention uses organosilicon resin as the film-forming body, which can greatly improve the heat resistance, water repellency and moisture resistance of the coating.

[0046] (3) The silica aerogel method of the present invention adopts a low cost, which does not require high-pressure equipment for supercritical drying, but only conventional drying ovens and reaction vessels, greatly reducing costs and eliminating cumbersome steps such as solvent replacement and high-pressure temperature control, and the production cycle is also shortened accordingly. There is no risk of high-pressure explosion in the atmospheric pressure environment, and VOCs emissions are far lower than those of the supercritical process.

[0047] (4) The present invention adds an appropriate amount of a specific type of elastomer component during a specific period of coating preparation, which can reduce the brittleness of the coating after the coating is formed and reduce the risk of the coating cracking and falling off. Attached Figure Description

[0048] Figure 1 The images show the smoothness of the coatings obtained in Example 1 and Comparative Examples 1-12. Detailed Implementation

[0049] The present invention will be further described below with reference to embodiments.

[0050] (I) The effect of silane coupling agents on the performance of coatings and coating layers Example 1 1) Preparation of silica aerogel by atmospheric pressure method: 15.6g of tetraethoxysilane and 4g of octyltrimethoxysilane were mixed, and then 46.5g of anhydrous ethanol-isopropanol 1:1 mixture was added and stirred evenly. Then, 9.4g of deionized water and 0.3g of 10wt% hydrochloric acid mixture were added, and the mixture was stirred at 1100rpm for 10min to obtain a transparent silica sol system. Then, 22.8g of n-heptane and 0.2g of polyethylene glycol were added, and the mixture was stirred at 1100rpm for 10min. Then, 0.7g of 30wt% ammonia water was added, and the mixture was stirred again for 1min. After standing for 20min, silica gel was obtained. The silica gel was transferred into a beaker and sealed with plastic wrap. Twenty small holes were punched in the top, and the mixture was aged at 40℃ for 12h. After aging, the sample was first dried in a 30℃ drying oven for 6 hours, then heated to 50℃ for 8 hours, and finally heated to 70℃ for 10 hours until the sample weight no longer changed, thus obtaining silica aerogel obtained by atmospheric pressure method.

[0051] 2) Preparation of aerogel slurry: Mix 5g KH-560, 5g deionized water, and 25g anhydrous ethanol, then add 50wt% formic acid to adjust the pH to 3.5. Stir at room temperature for 1h to fully hydrolyze KH-560 and obtain hydrolysate. Then, grind the silica aerogel produced by atmospheric pressure method in a grinding device and sieve it through a 500-mesh sieve to obtain fine powder. Take 5g of the sieved aerogel powder and 70g of anhydrous ethanol, place them in a reaction vessel at 50℃ and stir for 1h. Then, add 10g of hydrolysate dropwise and react at a constant temperature for 1h. After the reaction, filter, wash three times with anhydrous ethanol, and dry at 80℃ for 2h to obtain modified aerogel powder. Finally, mix 15g of modified aerogel powder, 82g of deionized water, and 3g of Tween-80 and stir at 300rpm for 30min to obtain aerogel slurry.

[0052] 3) Preparation of resin color paste: 65g of silicone resin, 25g of hollow glass microspheres, 15g of nano TiO2, 10g of elastomer component (hydroxyl-terminated polydimethylsiloxane elastomer (PMX-0156) and polyurethane modified silane prepolymer (XP2678) mixed in a 1:1 mass ratio), 1g of BYK-371, 1.2g of BYK-333 and 117.2g of zirconium beads were added to a dispersion tank and ground at 600rpm using a high-speed disperser. Samples were taken every 30min to check the fineness until the fineness of the color paste reached below 30μm. The zirconium beads were removed by filtration with a 300-mesh filter cloth to obtain the resin color paste.

[0053] 4) Preparation of silica aerogel thermal insulation coating: 53.5g aerogel slurry, 38.9g resin pigment, 0.5g BYK-077 and 2.2g propyl benzoate were added to a mixing tank and stirred at 800rpm for 1.5h. Then 6.5g ethylene glycol butyl ether was added and stirring was continued for 30min. The viscosity of the coating was then adjusted to 9000mPa·s with xylene to obtain silica aerogel thermal insulation coating.

[0054] 5) Apply the coating to the surface of the substrate and dry it at 150°C for 5 minutes to obtain a silica aerogel heat insulation coating.

[0055] Comparative Example 1 The only difference from Example 1 is that in step (2), the silica aerogel is not modified and KH-560 is not added. The remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of silica aerogel by atmospheric pressure method: Same as in Example 1.

[0056] 2) Preparation of aerogel slurry: Mix 5g of deionized water and 25g of anhydrous ethanol, then add 50wt% formic acid to adjust the pH to 3.5, and stir evenly at room temperature to obtain an ethanol solution. Then, grind the silica aerogel produced by atmospheric pressure method in a grinding device and sieve it through a 500-mesh sieve to obtain fine powder. Take 5g of the sieved aerogel powder and 70g of anhydrous ethanol, place them in a reaction vessel at 50℃ and stir for 1h. Then, add 10g of ethanol solution dropwise, and react at a constant temperature for 1h. After the reaction is completed, filter, wash three times with anhydrous ethanol, and dry at 80℃ for 2h to obtain aerogel powder. Finally, mix 15g of aerogel powder, 82g of deionized water and 3g of Tween-80, and stir at 300rpm for 30min to obtain an aerogel slurry.

[0057] 3) Preparation of resin pigment: Same as in Example 1.

[0058] 4) Preparation of silica aerogel thermal insulation coating: Same as in Example 1.

[0059] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0060] Comparative Example 2 The only difference from Example 1 is that the proportion of KH-560 is reduced in step (2), that is, the amount of hydrolysate added during modification is reduced to 2g. The remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of silica aerogel by atmospheric pressure method: Same as in Example 1.

[0061] 2) Preparation of aerogel slurry: Mix 5g KH-560, 5g deionized water, and 25g anhydrous ethanol, then add 50wt% formic acid to adjust the pH to 3.5. Stir at room temperature for 1h to fully hydrolyze KH-560 and obtain hydrolysate. Then, grind the silica aerogel produced by atmospheric pressure method in a grinding device and sieve it through a 500-mesh sieve to obtain fine powder. Take 5g of the sieved aerogel powder and 70g of anhydrous ethanol, place them in a reaction vessel at 50℃ and stir for 1h. Then, add 2g of hydrolysate dropwise and react at a constant temperature for 1h. After the reaction, filter, wash three times with anhydrous ethanol, and dry at 80℃ for 2h to obtain modified aerogel powder. Finally, mix 15g of modified aerogel powder, 82g of deionized water, and 3g of Tween-80 and stir at 300rpm for 30min to obtain aerogel slurry.

[0062] 3) Preparation of resin pigment: Same as in Example 1.

[0063] 4) Preparation of silica aerogel thermal insulation coating: Same as in Example 1.

[0064] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0065] Comparative Example 3 The only difference from Example 1 is that the proportion of KH-560 is increased in step (2), that is, the amount of hydrolysate added during modification is increased to 30g. The remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of silica aerogel by atmospheric pressure method: Same as in Example 1.

[0066] 2) Preparation of aerogel slurry: Mix 5g KH-560, 5g deionized water, and 25g anhydrous ethanol, then add 50wt% formic acid to adjust the pH to 3.5. Stir at room temperature for 1h to fully hydrolyze KH-560 and obtain hydrolysate. Then, grind the silica aerogel produced by atmospheric pressure method in a grinding device and sieve it through a 500-mesh sieve to obtain fine powder. Take 5g of the sieved aerogel powder and 70g of anhydrous ethanol, place them in a reaction vessel at 50℃ and stir for 1h. Then, add 30g of hydrolysate dropwise and react at a constant temperature for 1h. After the reaction, filter, wash three times with anhydrous ethanol, and dry at 80℃ for 2h to obtain modified aerogel powder. Finally, mix 15g of modified aerogel powder, 82g of deionized water, and 3g of Tween-80 and stir at 300rpm for 30min to obtain aerogel slurry.

[0067] 3) Preparation of resin pigment: Same as in Example 1.

[0068] 4) Preparation of silica aerogel thermal insulation coating: Same as in Example 1.

[0069] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0070] (II) The Influence of Elastomer Components on the Performance of Coatings and Coatings Comparative Example 4 The only difference from Example 1 is that no elastomer component is added in step (3); the remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of silica aerogel by atmospheric pressure method: Same as in Example 1.

[0071] 2) Preparation of aerogel slurry: Same as in Example 1.

[0072] 3) Preparation of resin color paste: 65g of silicone resin, 25g of hollow glass microspheres, 15g of nano TiO2, 1g of BYK-371, 1.2g of BYK-333 and 107.2g of zirconium beads were added to a dispersion tank and ground at 600rpm using a high-speed disperser. Samples were taken every 30min to check the fineness until the fineness of the color paste reached below 30μm. The zirconium beads were removed by filtration with a 300-mesh filter cloth to obtain the resin color paste.

[0073] 4) Preparation of silica aerogel thermal insulation coating: Same as in Example 1.

[0074] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0075] Comparative Example 5 The only difference from Example 1 is that the amount of elastomer component added in step (3) is reduced to 3g; the remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of supercritical silica aerogel: Same as in Example 1.

[0076] 2) Preparation of aerogel slurry: Same as in Example 1.

[0077] 3) Preparation of resin color paste: 65g of silicone resin, 25g of hollow glass microspheres, 15g of nano TiO2, 3g of elastomer component (hydroxyl-terminated polydimethylsiloxane elastomer (PMX-0156) and polyurethane modified silane prepolymer (XP2678) mixed in a mass ratio of 1:1), 1g of BYK-371, 1.2g of BYK-333 and 117.2g of zirconium beads were added to a dispersion tank and ground at 600rpm using a high-speed disperser. Samples were taken every 30min to check the fineness until the fineness of the color paste reached below 30μm. The zirconium beads were removed by filtration with a 300-mesh filter cloth to obtain the resin color paste.

[0078] 4) Preparation of silica aerogel thermal insulation coating: Same as in Example 1.

[0079] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0080] Comparative Example 6 The only difference from Example 1 is that the amount of elastomer component added in step (3) is increased to 25g; the remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of supercritical silica aerogel: Same as in Example 1.

[0081] 2) Preparation of aerogel slurry: Same as in Example 1.

[0082] 3) Preparation of resin color paste: 65g of silicone resin, 25g of hollow glass microspheres, 15g of nano TiO2, 25g of elastomer component (hydroxyl-terminated polydimethylsiloxane elastomer (PMX-0156) and polyurethane modified silane prepolymer (XP2678) mixed in a 1:1 mass ratio), 1g of BYK-371, 1.2g of BYK-333 and 117.2g of zirconium beads were added to a dispersion tank and ground at 600rpm using a high-speed disperser. Samples were taken every 30min to check the fineness until the color paste fineness reached below 30μm. The zirconium beads were removed by filtration with a 300-mesh filter cloth to obtain the resin color paste.

[0083] 4) Preparation of silica aerogel thermal insulation coating: Same as in Example 1.

[0084] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0085] Comparative Example 7 The only difference from Example 1 is that the elastomer component in step (3) is moved to step (4) as an additive; the remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of supercritical silica aerogel: Same as in Example 1.

[0086] 2) Preparation of aerogel slurry: Same as in Example 1.

[0087] 3) Preparation of resin color paste: 65g of silicone resin, 25g of hollow glass microspheres, 15g of nano TiO2, 1g of BYK-371, 1.2g of BYK-333 and 117.2g of zirconium beads were added to a dispersion tank and ground at 600rpm using a high-speed disperser. Samples were taken every 30min to check the fineness until the fineness of the color paste reached below 30μm. The zirconium beads were removed by filtration with a 300-mesh filter cloth to obtain the resin color paste.

[0088] 4) Preparation of silica aerogel thermal insulation coating: 53.5g of aerogel slurry, 38.9g of resin pigment, 10g of elastomer component (hydroxyl-terminated polydimethylsiloxane elastomer (PMX-0156) and polyurethane modified silane prepolymer (XP2678) mixed in a mass ratio of 1:1), 0.5g of BYK-077 and 2.2g of propyl benzoate were added to a mixing tank and stirred at 800rpm for 1.5h. Then 6.5g of ethylene glycol butyl ether was added and stirring was continued for 30min. The viscosity of the coating was then adjusted to 9000mPa·s with xylene to obtain silica aerogel thermal insulation coating.

[0089] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0090] Comparative Example 8 The only difference from Example 1 is that the elastomer component (a mixture of hydroxyl-terminated polydimethylsiloxane elastomer and polyurethane-modified silane prepolymer in a 1:1 mass ratio) in step (3) is replaced with carboxylated butadiene-acrylonitrile rubber elastomer (XNBR-40). The remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of silica aerogel by atmospheric pressure method: Same as in Example 1.

[0091] 2) Preparation of aerogel slurry: Same as in Example 1.

[0092] 3) Preparation of resin color paste: 65g of silicone resin, 25g of hollow glass microspheres, 15g of nano TiO2, 10g of carboxylated nitrile rubber elastomer (XNBR-40), 1g of BYK-371, 1.2g of BYK-333 and 117.2g of zirconium beads were added to a dispersion tank and ground at 600rpm using a high-speed disperser. Samples were taken every 30min to check the fineness until the fineness of the color paste reached below 30μm. The zirconium beads were removed by filtration with a 300-mesh filter cloth to obtain the resin color paste.

[0093] 4) Preparation of silica aerogel thermal insulation coating: Same as in Example 1.

[0094] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0095] Comparative Example 9 The only difference from Example 1 is that the elastomer component (a mixture of hydroxyl-terminated polydimethylsiloxane elastomer and polyurethane-modified silane prepolymer in a 1:1 mass ratio) in step (3) is replaced with a polyolefin elastomer (POE-1010). The remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of silica aerogel by atmospheric pressure method: Same as in Example 1.

[0096] 2) Preparation of aerogel slurry: Same as in Example 1.

[0097] 3) Preparation of resin color paste: 65g of silicone resin, 25g of hollow glass microspheres, 15g of nano TiO2, 10g of polyolefin elastomer (POE-1010), 1g of BYK-371, 1.2g of BYK-333 and 117.2g of zirconium beads were added to a dispersion tank and ground at 600rpm using a high-speed disperser. Samples were taken every 30min to check the fineness until the fineness of the color paste reached below 30μm. The zirconium beads were removed by filtration with a 300-mesh filter cloth to obtain the resin color paste.

[0098] 4) Preparation of silica aerogel thermal insulation coating: Same as in Example 1.

[0099] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0100] (III) The effects of aerogel slurry, resin pigment, and atmospheric pressure silica aerogel on the performance of coatings and coating layers. Comparative Example 10 The only difference from Example 1 is that the mass of the aerogel slurry is increased to 107g in step (4), while the remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of silica aerogel by atmospheric pressure method: Same as in Example 1.

[0101] 2) Preparation of aerogel slurry: Same as in Example 1.

[0102] 3) Preparation of resin pigment: Same as in Example 1.

[0103] 4) Preparation of silica aerogel thermal insulation coating: 107g of aerogel slurry, 38.9g of resin pigment, 0.5g of BYK-077 and 2.2g of propyl benzoate were added to a mixing tank and stirred at 800rpm for 1.5h. Then 6.5g of ethylene glycol butyl ether was added and stirring was continued for 30min. The viscosity of the coating was then adjusted to 9000mPa·s with xylene to obtain silica aerogel thermal insulation coating.

[0104] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0105] Comparative Example 11 The only difference from Example 1 is that the mass of the resin pigment in step (4) is increased to 80g; the remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of silica aerogel by atmospheric pressure method: Same as in Example 1.

[0106] 2) Preparation of aerogel slurry: Same as in Example 1.

[0107] 3) Preparation of resin pigment: Same as in Example 1.

[0108] 4) Preparation of silica aerogel thermal insulation coating: 53.5g aerogel slurry, 80g resin pigment, 0.5g BYK-077 and 2.2g propyl benzoate were added to a mixing tank and stirred at 800rpm for 1.5h. Then 6.5g ethylene glycol butyl ether was added and stirring was continued for 30min. The viscosity of the coating was then adjusted to 9000mPa·s with xylene to obtain silica aerogel thermal insulation coating.

[0109] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0110] Comparative Example 12 The only difference from Example 1 is that in step (1), the atmospheric pressure silica aerogel is replaced with the supercritical silica aerogel; the remaining steps, materials, and composition are the same as in Example 1. The specific steps are as follows: 1) Preparation of supercritical silica aerogel: 15.6 g of tetraethoxysilane and 4 g of octyltrimethoxysilane were mixed, and then 46.5 g of anhydrous ethanol-isopropanol 1:1 mixture was added and stirred evenly. Then, 9.4 g of deionized water and 0.3 g of 10 wt% hydrochloric acid mixture were added, and the mixture was stirred at 1100 rpm for 10 min to obtain a transparent silica sol system. Next, 22.8 g of n-heptane and 0.2 g of polyethylene glycol were added, and the mixture was stirred at 1100 rpm for 10 min. Then, 0.7 g of concentrated 30 wt% ammonia was added, and the mixture was stirred again for 1 min. After standing for 20 min, silica gel was obtained. The silica gel was transferred to a beaker and sealed with plastic wrap. Twenty small holes were punched in the top, and the mixture was aged at 30℃ for 36 h. The aerogel was replaced with anhydrous ethanol four times (10 h each time), and finally dried with supercritical CO2 at 45℃ and 9 MPa for 5 h to obtain supercritical silica aerogel.

[0111] 2) Preparation of aerogel slurry: Same as in Example 1.

[0112] 3) Preparation of resin pigment: Same as in Example 1.

[0113] 4) Preparation of silica aerogel thermal insulation coating: Same as in Example 1.

[0114] 5) Same as in Example 1, a silica aerogel heat insulation coating is obtained.

[0115] Example 2 1) Preparation of silica aerogel by atmospheric pressure method: 10g of tetraethoxysilane and 2g of octyltrimethoxysilane were mixed, and then 40g of anhydrous ethanol-isopropanol 1:1 mixture was added and stirred evenly. Then, 7g of deionized water and 0.2g of 10wt% hydrochloric acid mixture were added, and the mixture was stirred at 1100rpm for 10min to obtain a transparent silica sol system. Then, 20g of n-heptane and 0.1g of polyethylene glycol were added and stirred at high speed for 10min. Then, 0.5g of 30wt% ammonia water was added, and the mixture was stirred at high speed for 1min again. After standing for 20min, silica gel was obtained. The silica gel was transferred to a beaker and sealed with plastic wrap. 20 small holes were punched in the top, and the mixture was aged at 30℃ for 12h. After aging, the sample was dried in a drying oven at 30℃ for 6h, then the temperature was raised to 50℃ for 8h, and finally raised to 70℃ for 10h until the sample weight no longer changed, thus obtaining silica aerogel by atmospheric pressure method.

[0116] 2) Preparation of aerogel slurry: Mix 5g KH-560, 5g deionized water, and 25g anhydrous ethanol, then add 50wt% formic acid to adjust the pH to 3.5. Stir at room temperature for 1h to fully hydrolyze KH-560 and obtain hydrolysate. Then, grind the silica aerogel produced by atmospheric pressure method in a grinding device and sieve it through a 500-mesh sieve to obtain fine powder. Take 3g of the sieved aerogel powder and 60g of anhydrous ethanol, place them in a reaction vessel at 50℃ and stir for 1h. Then, add 5g of hydrolysate dropwise and react at a constant temperature for 1h. After the reaction, filter, wash three times with anhydrous ethanol, and dry at 80℃ for 2h to obtain modified aerogel powder. Finally, mix 10g of modified aerogel powder, 70g of deionized water, and 2g of Tween-80 and stir at 300rpm for 30min to obtain aerogel slurry.

[0117] 3) Preparation of resin color paste: 58g of silicone resin, 25g of hollow glass microspheres, 10g of nano TiO2, 10g of elastomer component (hydroxyl-terminated polydimethylsiloxane elastomer and polyurethane modified silane prepolymer mixed in a mass ratio of 1:1), 1g of BYK-371, 1g of BYK-333 and 105g of zirconium beads were added to a dispersion tank and ground at 600rpm using a high-speed disperser. Samples were taken every 30min to test the fineness until the fineness of the color paste reached below 30μm. The zirconium beads were removed by filtration with a 300-mesh filter cloth to obtain the resin color paste.

[0118] 4) Preparation of silica aerogel thermal insulation coating: 40g aerogel slurry, 30g resin pigment, 0.4g BYK-077 and 1.7g propyl benzoate were added to a mixing tank and stirred at 800rpm for 1.5h. Then 4.2g ethylene glycol butyl ether was added and stirring was continued for 30min. The viscosity of the coating was then adjusted to 9000mPa·s with xylene to obtain silica aerogel thermal insulation coating.

[0119] 5) Apply the coating to the surface of the substrate and dry it at 150°C for 5 minutes to obtain a silica aerogel heat insulation coating.

[0120] Example 3 1) Preparation of silica aerogel by atmospheric pressure method: 25g of tetraethoxysilane and 8g of octyltrimethoxysilane were mixed, and then 60g of anhydrous ethanol-isopropanol 1:1 mixture was added and stirred evenly. Then, 15g of deionized water and 0.8g of 10wt% hydrochloric acid mixture were added, and the mixture was stirred at 1100rpm for 10min to obtain a transparent silica sol system. Next, 30g of n-heptane and 0.4g of polyethylene glycol were added, and the mixture was stirred at 1100rpm for 10min. Then, 1.2g of 30wt% ammonia water was added, and the mixture was stirred again for 1min. After standing for 20min, silica gel was obtained. The silica gel was transferred to a beaker and sealed with plastic wrap. Twenty small holes were punched in the top, and the mixture was aged at 40℃ for 12h. After aging, the sample was first dried in a 30℃ drying oven for 6h, then the temperature was increased to 50℃ for 8h, and finally increased to 70℃ for 10h, until the sample weight no longer changed, thus obtaining the silica aerogel by atmospheric pressure method.

[0121] 2) Preparation of aerogel slurry: Mix 5g KH-560, 5g deionized water, and 25g anhydrous ethanol, then add 50wt% formic acid to adjust the pH to 3.5. Stir at room temperature for 1h to fully hydrolyze KH-560 and obtain hydrolysate. Then, grind the silica aerogel produced by atmospheric pressure method in a grinding device and sieve it through a 500-mesh sieve to obtain fine powder. Take 10g of the sieved aerogel powder and 85g of anhydrous ethanol, place them in a reaction vessel at 50℃ and stir for 1h. Then, add 15g of hydrolysate dropwise and react at a constant temperature for 1h. After the reaction, filter, wash three times with anhydrous ethanol, and dry at 80℃ for 2h to obtain modified aerogel powder. Finally, mix 20g of modified aerogel powder, 90g of deionized water, and 5g of Tween-80 and stir at 300rpm for 30min to obtain aerogel slurry.

[0122] 3) Preparation of resin color paste: 80g of silicone resin, 30g of hollow glass microspheres, 20g of nano TiO2, 15g of elastomer component (hydroxyl-terminated polydimethylsiloxane elastomer and polyurethane modified silane prepolymer mixed in a 1:1 mass ratio), 2g of BYK-371, 2.5g of BYK-333 and 134.5g of zirconium beads were added to a dispersion tank and ground at 600rpm using a high-speed disperser. Samples were taken every 30min to check the fineness until the color paste fineness reached below 30μm. The zirconium beads were removed by filtration with a 300-mesh filter cloth to obtain the resin color paste.

[0123] 4) Preparation of silica aerogel thermal insulation coating: 70g aerogel slurry, 45g resin pigment, 1g BYK-077 and 4g propyl benzoate were added to a mixing tank and stirred at 800rpm for 1.5h. Then 12g ethylene glycol butyl ether was added and stirred for another 30min. The viscosity of the coating was then adjusted to 9000mPa·s with xylene to obtain silica aerogel thermal insulation coating.

[0124] 5) Apply the coating to the surface of the substrate and dry it at 150°C for 5 minutes to obtain a silica aerogel heat insulation coating.

[0125] Performance testing The coating samples obtained in each embodiment and comparative example were tested for thermal conductivity, coating adhesion, coating smoothness, viscosity stability, and crack resistance. Thermal conductivity was tested according to GB / T 10294-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Protective Hot Plate Method" (25℃ environment). Coating adhesion was tested according to GB / T 5210-2006 "Adhesion Test of Paints and Varnishes - Pull-Off Method". Coating smoothness was tested by preparing a 100μm wet film using a paint film applicator, drying at room temperature for 24 hours, and then visually observing for sagging, pinholes, and particle protrusions. Viscosity stability was tested by sealing the coating at 25℃ for 7 days, measuring the initial viscosity and the viscosity after 7 days, and calculating the viscosity change rate (change rate = |viscosity after 7 days - initial viscosity| / initial viscosity × 100%). Cracking resistance (90° bending test) was tested according to GB / T 13448-2019 standard. The coated sheet was precisely bent to 90° using a bending tester, pressure-sensitive tape was applied along the bent surface, pressed firmly, and then quickly peeled off. The coating peeling was observed. The test results are shown in Table 1. Figure 1 As shown.

[0126] Table 1 Based on the data in the table above and Figure 1 A comparison of the photos shows that: In Comparative Example 1, due to the lack of modification of the aerogel, the thermal conductivity increased to 0.154 W / (m·K), while the coating exhibited large-area shrinkage. This was because without the modification of KH-560, the hydroxyl groups on the aerogel surface were not shielded, leading to severe aggregation of hydrophilic groups, destruction of the nanoporous structure, and unobstructed heat conduction pathways. The aggregated particles caused shrinkage in the coating, resulting in extremely poor system stability. In Comparative Example 2, the amount of KH-560 added was reduced, resulting in insufficient silanol generated from the hydrolysis of the silane coupling agent. The aerogel surface modification was incomplete, remaining predominantly hydrophilic, with severe aggregation, decreased thermal insulation, weak interfacial bonding between the aerogel and resin, and reduced adhesion. In Comparative Example 3, the amount of KH-560 added was increased, resulting in a slight increase in thermal conductivity, while other properties remained almost unchanged. This was because excessive hydrolysate caused some silane self-condensation, generating amorphous siloxane precipitates, which slightly blocked the aerogel pores, slightly increasing the thermal conductivity but not inducing aggregation. Other properties remained basically maintained, indicating that the harm of excessive coupling agent was less than that of insufficient dosage.

[0127] In Comparative Example 4, no elastomer component was added. Due to the lack of hydroxyl-terminated polydimethylsiloxane and polyurethane-modified silane prepolymer, the film layer lacked an elastic buffer network. Shrinkage stress could not be released during 90° bending, leading to coating cracking. However, the elastomer did not affect thermal insulation and dispersion, so the thermal conductivity and viscosity stability remained basically normal. In Comparative Example 5, the amount of elastomer component added was reduced, resulting in insufficient elastic components in the coating and significantly reduced crack resistance. Shrinkage stress could not be effectively released after bending, making the coating prone to cracking and peeling. In Comparative Example 6, the amount of elastomer component added was increased, resulting in redundant coating toughness and poor film-forming properties. Furthermore, the excessive elastomer filled some aerogel pores, shortening the heat conduction path, thus significantly increasing thermal conductivity. Other properties remained largely unchanged.

[0128] In Comparative Example 7, the elastomer component was changed from the filler in step (3) to the additive in step (4). In this case, the elastomer failed to fully grind and fuse with the resin pigment, resulting in localized agglomerated particles. This significantly reduced the uniformity of dispersion in the coating system, leading to a noticeable grainy texture in the coating. Furthermore, because it could not form a continuous elastic network, it could not provide sufficient cushioning during bending, thus slightly reducing crack resistance. Simultaneously, the agglomerated particles also damaged the original intact thermal insulation structure, further reducing the coating's thermal insulation performance. Therefore, all performance characteristics declined significantly. This demonstrates that the timing of adding the elastomer component is crucial.

[0129] In Comparative Example 8, the elastomer component was replaced with an equal mass of carboxylated nitrile rubber elastomer (XNBR-40). XNBR-40 had poor compatibility with the resin system and could not be ground uniformly, resulting in a slightly grainy texture. This compromised the coating's density, increased thermal conductivity, and prevented the formation of a continuous elastic network due to uneven dispersion. During 90° bending, stress concentrated at particle agglomerations, leading to localized detachment. This demonstrates that the type of elastomer component is also crucial. In Comparative Example 9, the elastomer component was replaced with an equal mass of polyolefin elastomer (POE-1010). POE-1010 had even worse compatibility with the resin system and could not be ground uniformly, resulting in large localized particles. These large particles disrupted the nanoporous thermal insulation structure of the aerogel, shortened the heat conduction path, and significantly reduced thermal insulation performance. Incompatible POE particles also created interfacial defects in the resin matrix, weakening the adhesion between the coating and the substrate.

[0130] In Comparative Example 10, the proportion of aerogel slurry was too high, which caused some silica aerogel particles to agglomerate, resulting in a grainy coating. However, due to the increase in the thermal insulation component, the overall thermal insulation performance increased. The significant reduction in the resin component led to severe cracking of the coating after bending.

[0131] In Comparative Example 11, the proportion of resin pigment was too high, the coating was mainly composed of silicone resin, and the heat insulation component was reduced, thus the heat insulation performance was reduced, the adhesion was increased, and the viscosity change rate was slightly improved.

[0132] In Comparative Example 12, the supercritical method was used instead of the atmospheric pressure method. The supercritical dried aerogel has higher porosity and more complete structure, so its thermal insulation performance is slightly better than that of the atmospheric pressure method. However, the preparation requires high-pressure equipment, and the cost is several times that of the atmospheric pressure method. Moreover, the process is complex and cannot be mass-produced, which does not meet the core advantages of low cost and industrialization.

Claims

1. A silica aerogel heat-insulating coating, characterized in that: The raw materials include the following parts by weight: 40-70 parts aerogel paste, 30-45 parts resin color paste, 0.5-3 parts spraying additive, and 4-8 parts solvent; The aerogel slurry comprises the following raw materials in parts by weight: 3-10 parts of atmospheric pressure silica aerogel, 0.5-1 part of silane coupling agent, 2-5 parts of surfactant, 70-90 parts of water, 60-85 parts of anhydrous ethanol, and pH adjuster. The atmospheric pressure silica aerogel comprises the following raw materials in parts by weight: 10-25 parts tetraethoxysilane, 2-8 parts octyltrimethoxysilane, 20-30 parts n-heptane, 40-60 parts anhydrous ethanol-isopropanol mixture, 1-3 parts catalyst, 0.1-0.4 parts polyethylene glycol, and 7-15 parts water. The resin color paste comprises the following raw materials in parts by weight: 50-80 parts of organosilicon resin, 40-60 parts of pigments and fillers, 10-15 parts of elastomer components, and 1-6 parts of additives. The elastomer component is selected from hydroxyl-terminated polydimethylsiloxane elastomer and polyurethane-modified silane prepolymer.

2. The silica aerogel thermal insulation coating as described in claim 1, characterized in that: The spraying aids include defoamers and film-forming aids; The solvent includes one or more of toluene, xylene, ethylene glycol butyl ether, and methyl isobutyl ketone; The silane coupling agent is KH-560; The surfactant is Tween-80; The pH adjuster is a 45-55 wt% formic acid solution; The catalyst comprises a 5-15 wt% hydrochloric acid solution and an ammonia solution with a concentration of 30-40 wt%. The pigments and fillers include one or more of ATO powder, hollow glass microspheres, and nano-TiO2; The additives include wetting and dispersing agents and leveling agents.

3. The silica aerogel thermal insulation coating as described in claim 2, characterized in that: The wetting and dispersing agent includes one or more of BYK-307, BYK-371, and TEGO Dispers 610; The leveling agent includes one or more of BYK-333, BYK-306, and TEGO Glide 410; The defoamer includes one or more of BYK-052, BYK-077, and TEGO Airex 9100; The film-forming aid includes one or more of alcohol ester twelve, alcohol ester sixteen, and propyl benzoate.

4. A method for preparing a silica aerogel thermal insulation coating as described in any one of claims 1-3, characterized in that... include: (1) Tetraethoxysilane and octyltrimethoxysilane were mixed and then anhydrous ethanol-isopropanol mixture was added and stirred evenly. Water and part of the catalyst were added and stirred to obtain a transparent silica sol system. Heptane and polyethylene glycol were added and stirred. Part of the catalyst was added and stirred again. After standing, silica gel was obtained. The silica gel was aged. After aging, it was dried at 30-35℃ for 6-8h, then heated to 50-55℃ for 8-10h, and finally heated to 70-75℃ for 6-10h to obtain atmospheric pressure silica aerogel. (2) Mix and stir the silane coupling agent, water, anhydrous ethanol and pH adjuster to hydrolyze the silane coupling agent to obtain hydrolysate; grind the silica aerogel by atmospheric pressure method into aerogel powder, sieve it and mix it with anhydrous ethanol, add the hydrolysate dropwise, filter, wash and dry after reaction to obtain modified aerogel powder. Modified aerogel powder, water, and surfactant are mixed and stirred to obtain an aerogel slurry; (3) Mix the silicone resin, pigments, fillers, elastomer components and additives, ball mill and filter to obtain resin paste; (4) Mix the aerogel slurry, resin pigment and spraying additive evenly, and adjust the viscosity of the coating with solvent to obtain silica aerogel heat insulation coating.

5. The preparation method according to claim 4, characterized in that: In step 1): The stirring speed is 1100-1500 rpm; The aging temperature is 30-50℃.

6. The preparation method according to claim 4, characterized in that: In step 2): The mixing time for the first time is 0.5-2 hours; The sieving process is a 400-600 mesh sieve; The reaction is carried out at a temperature of 40-70℃ for a time of 0.5-1h. The cleaning process uses anhydrous ethanol. The second mixing and stirring is performed at a speed of 250-350 rpm for 0.5-1 h.

7. The preparation method according to claim 4, characterized in that: In step 3): The mass ratio of grinding balls to raw materials during ball milling is 1:0.8-1.2; The ball mill operates at a speed of 400-600 rpm for 3-7 hours. The fineness of the pigment is less than 30 μm.

8. The preparation method according to claim 4, characterized in that: In step 4): The stirring speed is 500-800 rpm; The viscosity of the coating is 7000-11000 mPa·s.

9. The application of the silica aerogel thermal insulation coating according to any one of claims 1-3 or the silica aerogel thermal insulation coating obtained by the preparation method according to any one of claims 4-8 in the preparation of thermal insulation coatings, characterized in that... include: The coating is applied to the surface of the substrate and heated to dry, resulting in a silica aerogel heat insulation coating.

10. The application as described in claim 9, characterized in that: The drying temperature is 150-250℃, and the time is 5-15 minutes.

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