Thermal insulation coating and preparation method thereof

Abstract

The invention discloses a thermal insulation coating and a preparation method thereof, and relates to the technical field of coatings. The heat insulation and heat preservation coating is prepared from cross-linked coated modified SiO2 aerogel hybrid microspheres, modified basic slurry, flaky zinc-aluminum powder and polymethylphenyl organic silicon resin, the cross-linked, coated and modified SiO2 aerogel hybrid microspheres are uniformly embedded into a modified basic slurry network, countless tiny heat insulation units are formed in a three-dimensional nano thermal barrier network, heat conduction is effectively inhibited and blocked, the heat insulation and heat preservation performance is improved, meanwhile, the coating is endowed with extremely high hydrophobicity and permeability resistance, the waterproof performance is remarkably enhanced, and in addition, the coating has a good application prospect. The three-dimensional nano network fixedly wraps the cross-linked and coated modified SiO2 aerogel hybrid microspheres, so that not only is the overall mechanical durability improved and the risk of falling off and abrasion reduced, but also the immersion and permeation of a corrosive medium can be further reduced by a compact barrier effect, and the durability of the coating is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of coatings, and particularly relates to a heat insulation coating and a preparation method thereof. BACKGROUND

[0002] The energy consumption of a building mainly comes from heating and cooling systems required for maintaining the comfortable temperature in the building envelope, and the heat conduction of the building wall and roof accounts for about 40% of the total heat load of a typical building. The most widely used wall insulation form in the market is external wall insulation, that is, using extruded polystyrene board, rock wool board, polyurethane foam board, expanded polystyrene board and other insulation materials to bond to the surface of the building external wall to block the conduction of heat energy, so as to achieve the purpose of building insulation. However, such insulation system has great construction difficulty, and the insulation board has great thickness, strong elasticity and easy deformation, and is prone to cracking and falling off, thereby causing safety hazards.

[0003] The heat insulation coating is a building external wall and roof coating material with heat insulation and insulation effects, and forms a heat conduction barrier layer with certain strength and elasticity after drying and curing. The coating thickness only needs to be 2-3 mm to achieve the insulation effect of the traditional insulation system, and it is an ideal building external wall insulation and heat insulation material.

[0004] The existing technology mainly has the following problems:

[0005] The existing insulation coating has poor water resistance and durability, and is prone to problems such as coating cracking, leakage, falling off and wear, thereby limiting the stable and effective play of the heat insulation performance of the coating. SUMMARY

[0006] In view of the above situation, in order to overcome the defects of the prior art, the application provides a heat insulation coating, which comprises the following components in parts by weight: cross-linked coated modified SiO2 aerogel hybrid microspheres 20-30 parts, modified base slurry 50-60 parts, sheet-like zinc aluminum powder 1-3 parts, and polymethylphenyl silicone resin 2-4 parts.

[0007] The cross-linked coated modified SiO2 aerogel hybrid microspheres comprise the following components in parts by weight: glutarate agarose 8-10 parts, polyvinyl alcohol 3-5 parts, polyvinyl butyral 2-4 parts, hydrophobic SiO2 aerogel 20-30 parts, and methyltrimethoxysilane 5-10 parts.

[0008] The modified base paste is made of the following components by weight: carbon nanotubes 0.3-0.5 parts, graphene oxide 0.2-0.4 parts, epoxy resin 40-50 parts, barium sulfate 8-10 parts, graphite powder 10-15 parts, glass microbeads 5-10 parts, BYK-2150 dispersant 0.1-0.3 parts, BYK-333 leveling agent 0.5-0.8 parts, TEGO805 defoaming agent 0.2-0.4 parts.

[0009] The preparation method of the cross-linked coated modified SiO2 aerogel hybrid microspheres specifically comprises the following steps:

[0010] (1) 4.0-5.0 g of agarose is dispersed in 250 mL of N,N-dimethylformamide solvent, heated to 40-50°C and simultaneously subjected to magnetic stirring, the stirring is continuously performed for 3-4 h, then 1.0-2.0 g of carbodiimide hydrochloride, 0.8-1.0 g of 4-dimethylaminopyridine are added, finally glutaric acid is added, the reaction is performed at 30-40°C for 3-4 h, then the agarose is precipitated using an ethanol solution with a mass fraction of 95% and is suction filtered, the washing is repeated for 2-4 times, the precipitate is dried in an oven at 40°C for 18-20 h, through the modification treatment of glutaric acid, the hydrophobic chain segment is simultaneously introduced into the agarose and a strong cross-linked network is constructed, the waterproofness, mechanical durability and long-acting thermal insulation of the agarose as a coating filler are improved, and in addition, the compatibility and affinity with the hydrophobic SiO2 aerogel in the subsequent process are also favorable, and the glutarate agarose is obtained;

[0011] (2) 0.3-0.5g polyvinyl alcohol, glutarate agarose described in step (1) is dispersed in an 80% ethanol solution, dissolved under stirring in a water bath at 80-85°C, then 0.2-0.4g polyvinyl butyral is added, and magnetic stirring is performed at 200-300rpm for 1-2h, to obtain a polymer solution for use, 2.0-3.0g hydrophobic SiO2 aerogel is dispersed in 30mL of an 80% ethanol solution, and ultrasonic assistance is performed for 30-40min to obtain a hydrophobic SiO2 aerogel dispersion for use, then the hydrophobic SiO2 aerogel dispersion is slowly added to the polymer solution, stirring is performed at 80-85°C and 700-800rpm for 0.5-1h, and the mixture is left to stand for 10-20min to obtain a mixture for use, 200-300mL of dimethyl silicone oil is preheated to 80-85°C and stirred at 800-1000rpm for 8-10min, then the mixture is slowly added to the pre-treated dimethyl silicone oil, and stirring is continued for 30-60min, the precipitated solid is washed with anhydrous ethanol, a 90% ethanol solution and deionized water for 3-5 times, the hydrophobic SiO2 aerogel is modified by the polymer system of polyvinyl alcohol, glutarate agarose and polyvinyl butyral, which effectively improves the thermal insulation performance, waterproof performance and durability of the aerogel, wherein the polymer is coated on the surface of the hydrophobic SiO2 aerogel, without damaging the pore structure of the aerogel, effectively blocking the transfer and loss of heat, the barrier effect of the coating layer can isolate part of the silicon hydroxyl groups on the surface of the aerogel, further enhancing the hydrophobicity of the whole, polyvinyl butyral acts as a toughening agent, forming a flexible polymer coating layer that effectively absorbs and disperses energy, inhibiting the generation and expansion of microcracks, at the same time, the hard hydrophobic SiO2 aerogel core not only ensures the hardness and wear resistance, but also resists acid and alkali corrosion, and the polymer coating layer also helps to isolate the contact between corrosive substances and the aerogel core, thus enhancing the overall thermal insulation, waterproof and durability, obtaining a coated and modified SiO2 aerogel;

[0012] (3) 150 mL of 90% ethanol solution is adjusted to pH 4.0-5.0 with glacial acetic acid, 5-10 mL of methyltrimethoxysilane is added under magnetic stirring, and stirring is continued for 30-60 min to obtain a hydrolysis solution, then the coated modified SiO2 aerogel in step (2) is added, and the mixture is incubated in a 40-50°C water bath under low-speed stirring for 6-12 h, the stirring speed is 100-200 rpm, and the obtained solid product is washed with anhydrous ethanol and deionized water for 3-5 times in sequence, the washed wet product is soaked with t-butyl alcohol for 3 times, each time for 2-3 h, and after replacement, the product is placed in a 40-50°C vacuum drying oven for drying for 24-48 h; the methyltrimethoxysilane not only forms Si-O-C covalent bonds with the hydroxyl groups of the coated modified SiO2 aerogel, but also forms a dense Si-O-Si three-dimensional network in an intermolecular self-condensation manner, penetrates and reinforces the polymer coating layer, the unreacted hydrophobic methyl groups are densely arranged on the outermost side to form a lotus leaf surface, so that water molecules are difficult to wet, meanwhile, the stable and firm Si-O-Si chemical bonds greatly enhance the interfacial bonding force between the polymer coating layer and the hydrophobic SiO2 aerogel core, avoid the coating layer from falling off, and make the filler particles more resistant to wear and extrusion; through the crosslinking treatment of methyltrimethoxysilane, the network of the structure surface of the coated modified SiO2 aerogel is strengthened, hydrophobic groups are introduced, and a firm, durable and super-hydrophobic siloxane protective layer is constructed, so that the integrity and stability of the nano-porous structure of the aerogel are ensured, the heat insulation and thermal preservation performance can be stably exerted for a long time, and the crosslinked coated modified SiO2 aerogel hybrid microspheres are obtained;

[0013] Preferably, in step (1), the addition amount of glutaric acid is 2.5-3.5 g; the addition of glutaric acid not only introduces a hydrophobic segment (-CO- (CH2) 3-COOH) on the agarose molecule, but also reacts with the hydroxyl groups on two different agarose molecular chains to form a chemical crosslinking point, so that the linear agarose molecules are connected into a three-dimensional network structure.

[0014] Preferably, in step (2), the hydrophobic SiO2 aerogel is KNF-W50, which has ultra-low density, low thermal conductivity and extremely high porosity, and can be used as a functional filler to improve the thermal insulation performance of the heat insulation coating.

[0015] The application also provides a preparation method of the heat insulation coating, which specifically comprises the following steps:

[0016] S1, 0.3-0.5g carbon nanotubes, 0.1-0.3g BYK-2150 dispersant is added to 26ml N,N-dimethylformamide solvent, ultrasonic treatment for 30-40min, then add 0.2-0.4g graphene oxide powder, ultrasonic dispersion for 40-50min, get carbon nanotube and graphene oxide composite dispersion, ready for use, then the carbon nanotube and graphene oxide composite dispersion and 40.0-50.0g epoxy resin, 8.0-10.0g barium sulfate, 10.0-15.0g graphite powder, 0.5-0.8g BYK-333 leveling agent, 0.2-0.4g TEGO805 defoamer is mixed uniformly, grinding to the fineness of slurry <25μm, slowly add 5.0-10.0g glass beads under stirring at 300-600rpm, continue stirring for 20-30min, finally pass through 120 mesh screen, in this process, graphene oxide provides sheet barrier, block heat conduction, prolong the heat path, carbon nanotubes fill in the graphene oxide sheet, form a network structure similar to reinforced cement, not only provide basic strength and toughness, reduce the risk of cracking, shedding, wear and tear, improve mechanical durability, but also through the three-dimensional nano thermal barrier network effectively trapped heat, combined with zero-dimensional glass beads on the gas phase conduction and direct inhibition of convection, the full inhibition of heat transfer, at the same time, this close filling sheet barrier, further prolong the tortuous path needed to pass through by water and corrosion medium penetration, enhance the waterproof and corrosion resistance, get modified base slurry;

[0017] S2, slowly add the modified base slurry in step S1 under stirring at 300-600 rpm, after complete addition, stir at 600-800 rpm for 15-20 min, then add 2.0-4.0 g of polymethylphenyl silicone resin, stir for 20-30 min, then slowly add the cross-linked coated modified SiO2 aerogel hybrid microspheres under stirring at 200-400 rpm, continue stirring for 20-30 min after complete addition, by embedding the cross-linked coated modified SiO2 aerogel hybrid microspheres in the modified base slurry network, a large number of uniformly dispersed cross-linked coated modified SiO2 aerogel hybrid microspheres form countless small adiabatic units, which is equivalent to setting countless barriers, greatly extending the path of heat transfer, effectively blocking heat conduction, significantly improving the thermal insulation performance, and the aerogel microspheres are not easy to be lost due to wear, erosion or aging, and the embedded aerogel microspheres can also improve the mechanical properties of the modified base slurry, effectively hinder the expansion of cracks, at the same time, the hydrophobic cross-linked coated modified SiO2 aerogel hybrid microspheres dispersed in the modified base slurry not only impart excellent water resistance to the coating, but also further reduce the immersion and penetration of water and corrosive media with the dense barrier effect, which is beneficial to improve the durability of the coating, and the thermal insulation coating is obtained.

[0018] Preferably, in step S1, the carbon nanotube type is multi-walled carbon nanotube, the diameter is 5-9 nm, and the length is 0.5-1.0 μm, the carbon nanotube with smaller diameter and shorter length is easy to bend and wind, and it is difficult to connect with other carbon nanotubes, thereby preventing the formation of long-range and high-efficiency heat conduction network by connecting the carbon nanotubes end to end, and the interface exists between the layers of the multi-walled carbon nanotube, and the phonon is scattered when transferring between the layers, thereby reducing the thermal conductivity and being beneficial to enhancing the thermal insulation performance.

[0019] Preferably, in step S2, the addition amount of the flaky zinc-aluminum powder is 1.0-3.0 g, and the average particle size is 5-7 μm, the flaky zinc-aluminum powder as a hard alloy particle can improve the hardness and wear resistance of the coating, and prolong the penetration path of the corrosive medium, thereby improving the durability of the coating.

[0020] The beneficial effects obtained by the present application are as follows:

[0021] This invention uniformly embeds cross-linked modified SiO2 aerogel hybrid microspheres into a modified base slurry network, forming numerous tiny insulating units within a three-dimensional nano-thermal barrier network. This effectively inhibits and blocks heat conduction, improving thermal insulation performance. Simultaneously, it endows the coating with strong hydrophobicity and impermeability, significantly enhancing waterproofing. Furthermore, the three-dimensional nano-network firmly encapsulates the cross-linked modified SiO2 aerogel hybrid microspheres, not only improving overall mechanical durability and reducing the risk of cracking, peeling, and wear, but also further reducing the infiltration and penetration of corrosive media through a dense barrier effect, thus improving coating durability and ensuring the stable and effective performance of the coating's thermal insulation properties. The cross-linked... In the coated and modified SiO2 aerogel hybrid microspheres, a polymer system of polyvinyl alcohol, glutarate-esterified agarose, and polyvinyl butyral was first used to coat and modify the hydrophobic SiO2 aerogel. The polymer coating on the surface of the hydrophobic SiO2 aerogel increased the difficulty of heat flow through through an enhanced labyrinth effect, blocking heat transfer and loss. The barrier effect of the coating layer isolated some of the silanol groups on the aerogel surface, further enhancing the overall hydrophobicity. The flexible polymer coating layer effectively absorbed and dispersed energy, inhibiting the generation and propagation of microcracks. The rigid hydrophobic SiO2 aerogel core provided hardness and wear resistance, and its chemical inertness and porous structure also resisted and extended… The process of slowing down acid and alkali corrosion is followed by cross-linking treatment of the coated modified SiO2 aerogel with methyltrimethoxysilane. Methyltrimethoxysilane forms a dense three-dimensional Si-O-Si network through intermolecular self-condensation, penetrating and reinforcing the polymer coating layer. Its unreacted hydrophobic methyl groups are densely arranged on the outermost side, forming a lotus leaf-like surface that makes it difficult for water molecules to wet, exhibiting strong hydrophobicity and reducing the penetration channels of corrosive media. Simultaneously, the Si-O-Si chemical bonds greatly enhance the interfacial bonding force between the polymer coating layer and the hydrophobic SiO2 aerogel, preventing coating layer detachment and making the filler particles more wear-resistant and compression-resistant. In the modified base slurry, in the epoxy resin matrix... One-dimensional carbon nanotubes and two-dimensional graphene oxide nano-reinforcing phases are introduced to form a network structure similar to steel bars and cement, providing basic strength and toughness and reducing the risk of detachment and wear. This three-dimensional nano thermal barrier network can effectively trap heat. Combined with the direct inhibition of gas phase conduction and convection by zero-dimensional glass microspheres, it achieves all-round suppression of heat transfer. At the same time, this tightly filled sheet barrier further extends the tortuous path required for the penetration of water and corrosive media, enhances waterproofness and corrosion resistance, and is also conducive to enhancing durability. Furthermore, this nano network can also adsorb and entangle on the surface of cross-linked coated modified SiO2 aerogel hybrid microspheres, stably fixing them in the coating matrix.This invention utilizes cross-linked modified SiO2 aerogel hybrid microspheres, modified base slurry, flake zinc-aluminum powder, and polymethylphenyl silicone resin to create a thermal insulation coating. This coating enhances waterproofing and durability, ensuring effective thermal insulation performance. Attached Figure Description

[0022] Figure 1 The graph shows the temperature difference results of Examples 1-4 and Comparative Examples 1-3 of the present invention;

[0023] Figure 2 The graph shows the water absorption rate results of Examples 1-4 and Comparative Examples 1-3 of the present invention;

[0024] Figure 3 The figures show the volume wear rate results for Examples 1-4 and Comparative Examples 1-3 of the present invention.

[0025] Figure 4 The diagram shows the failure area percentage results for Examples 1-4 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0028] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods; unless otherwise specified, the experimental materials used in the following embodiments are all purchased from commercial channels.

[0029] Example 1

[0030] This embodiment proposes a heat insulation coating comprising the following components in parts by weight: 30 parts of cross-linked modified SiO2 aerogel hybrid microspheres, 60 parts of modified base slurry, 3 parts of flake zinc-aluminum powder, and 4 parts of polymethylphenyl silicone resin.

[0031] Cross-linked coated modified SiO2 aerogel hybrid microspheres comprise the following components in parts by weight: 10 parts glutarate esterified agarose, 5 parts polyvinyl alcohol, 4 parts polyvinyl butyral, 30 parts hydrophobic SiO2 aerogel, and 10 parts methyltrimethoxysilane.

[0032] The modified base slurry is made from the following components in parts by weight: 0.5 parts carbon nanotubes, 0.4 parts graphene oxide, 50 parts epoxy resin, 10 parts barium sulfate, 15 parts graphite powder, 10 parts glass microspheres, 0.3 parts BYK-2150 dispersant, 0.8 parts BYK-333 leveling agent, and 0.4 parts TEGO805 defoamer.

[0033] The preparation method of cross-linked coated modified SiO2 aerogel hybrid microspheres specifically includes the following steps:

[0034] (1) Disperse 5.0 g of agarose in 250 mL of N,N-dimethylformamide solvent, heat to 50 °C and stir magnetically for 4 h. Then add 2.0 g of carbodiimide hydrochloride and 1.0 g of 4-dimethylaminopyridine. Finally, add 3.5 g of glutaric acid. The addition of glutaric acid can not only graft hydrophobic segments (-CO-(CH2)3-COOH) onto the agarose molecules, but also react with the hydroxyl groups on two different agarose molecular chains to form chemical cross-linking points, thus transforming the linear... Agarose molecules were linked into a three-dimensional network structure and reacted at 40℃ for 4 hours. Then, agarose was precipitated with a 95% ethanol solution and filtered. The washing was repeated 4 times, and the precipitate was dried in an oven at 40℃ for 20 hours. Through glutaric acid modification, hydrophobic segments and a robust cross-linked network were introduced into the agarose, which improved the waterproofness, mechanical durability and long-term thermal insulation properties of agarose as a coating filler. In addition, it also facilitated the compatibility and affinity with hydrophobic SiO2 aerogel, resulting in glutaric acid-esterified agarose.

[0035] (2) Disperse 0.5g of polyvinyl alcohol and the glutaric acid esterified agarose described in step (1) in an 80% ethanol solution and stir to dissolve in an 85°C water bath. Then add 0.4g of polyvinyl butyral and stir magnetically for 2 hours at a stirring speed of 300 rpm to obtain a polymer solution for later use. Disperse 3.0g of hydrophobic SiO2 aerogel in 30mL of an 80% ethanol solution. The hydrophobic SiO2 aerogel is brand KNF-W50, which has ultra-low density, low thermal conductivity and extremely high thermal conductivity. Porosity can be used as a functional filler in thermal insulation coatings to improve thermal insulation performance. After ultrasonic assisted stirring for 40 minutes, a hydrophobic SiO2 aerogel dispersion was obtained and set aside. Then, the hydrophobic SiO2 aerogel dispersion was slowly added to the polymer solution, and stirred at 85℃ and 800rpm for 1 hour. After standing for 20 minutes, a mixed solution was obtained and set aside. 300mL of dimethyl silicone oil was preheated to 85℃ and stirred at 1000rpm for 10 minutes. The mixed solution was then slowly added to the pretreated dimethyl silicone oil and stirred for 1 hour. After stirring for 60 minutes, the precipitated solid was washed five times successively with anhydrous ethanol, 90% ethanol solution, and deionized water. The hydrophobic SiO2 aerogel was modified by coating it with a polymer system of polyvinyl alcohol, glutaric acid-esterified agarose, and polyvinyl butyral. This effectively improved the aerogel's thermal insulation, waterproofing, and durability. The polymer coating on the surface of the hydrophobic SiO2 aerogel did not damage its porous structure, effectively blocking heat transfer and loss. The barrier effect of the coating layer effectively isolated the gas... The partial silanol groups on the gel surface further enhance the overall hydrophobicity. Polyvinyl butyral acts as a toughening agent, forming a flexible polymer coating layer that effectively absorbs and disperses energy, inhibiting the generation and propagation of microcracks. Meanwhile, the hard, hydrophobic SiO2 aerogel core not only ensures hardness and wear resistance but also resists acid and alkali corrosion. The polymer coating layer also helps to isolate corrosive substances from contact with the aerogel core, thus enhancing the overall thermal insulation, waterproofing, and durability, resulting in a coated modified SiO2 aerogel.

[0036] (3) Adjust the pH of 150 mL of 90% ethanol solution to 5.0 using glacial acetic acid. Add 10 mL of methyltrimethoxysilane under magnetic stirring and continue stirring for 60 min to obtain a hydrolysate for later use. Then add the coated modified SiO2 aerogel described in step (2) and keep it warm in a 50℃ water bath with low-speed stirring for 12 h at a stirring speed of 200 rpm. Filter the mixture and wash the obtained solid product with anhydrous ethanol and deionized water five times in sequence. Soak the washed wet product in tert-butanol three times for 3 h each time. After the replacement, dry it in a vacuum drying oven at 50℃ for 48 h. Methyltrimethoxysilane not only forms Si-OC covalent bonds with the hydroxyl groups of the polymer in the coated modified SiO2 aerogel, but also forms dense Si-O- through intermolecular self-condensation. A three-dimensional Si network penetrates and reinforces the polymer coating layer. Its unreacted hydrophobic methyl groups are densely arranged on the outermost side, forming a lotus leaf-like surface that makes it difficult for water molecules to wet. At the same time, this stable and strong Si-O-Si chemical bond greatly enhances the interfacial bonding force between the polymer coating layer and the hydrophobic SiO2 aerogel core, preventing the coating layer from falling off. This makes the filler particles more wear-resistant and compression-resistant. Through cross-linking treatment with methyltrimethoxysilane, the network of the coated and modified SiO2 aerogel structure is strengthened and hydrophobic groups are introduced, constructing a robust, durable, and superhydrophobic siloxane protective layer. This ensures the integrity and stability of the aerogel nanoporous structure, allowing the thermal insulation performance to be maintained stably for a long time, resulting in cross-linked coated and modified SiO2 aerogel hybrid microspheres.

[0037] This embodiment provides a method for preparing a heat-insulating coating, specifically including the following steps:

[0038] S1. Add 0.5g of carbon nanotubes and 0.3g of BYK-2150 dispersant to 26mL of N,N-dimethylformamide solvent. The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 9nm and a length of 1.0μm. Smaller diameter and shorter length carbon nanotubes are easily bent and entangled, making it difficult to connect with other carbon nanotubes. This prevents the formation of a long-range, highly efficient thermally conductive network by connecting end-to-end. The multi-walled carbon nanotubes have interfaces between layers, and phonons are scattered during interlayer transmission, thus reducing thermal conductivity and enhancing thermal insulation. Sonicate for 40min, then add 0.4g of graphene oxide powder and sonicate for 50min to obtain a composite dispersion of carbon nanotubes and graphene oxide. Set aside. Then, mix the composite dispersion of carbon nanotubes and graphene oxide with 50.0g of epoxy resin, 10.0g of barium sulfate, 15.0g of graphite powder, and 0.8g of B... YK-333 leveling agent and 0.4g TEGO805 defoamer are mixed evenly and ground until the fineness of the slurry is <25μm. 10.0g glass microspheres are slowly added while stirring at 600rpm, and stirring is continued for 30min. Finally, the mixture is passed through a 120-mesh sieve. In this process, graphene oxide provides a sheet barrier to block heat conduction and extend the heat path. Carbon nanotubes fill the spaces between the graphene oxide sheets, forming a network structure similar to reinforced concrete. This not only provides basic strength and toughness, reducing the risk of cracks, detachment, and wear, and improving mechanical durability, but also effectively traps heat through the three-dimensional nano-thermal barrier network. Combined with the direct inhibition of gas phase conduction and convection by zero-dimensional glass microspheres, comprehensive inhibition of heat transfer is achieved. At the same time, this tightly filled sheet barrier further extends the tortuous path required for the penetration of moisture and corrosive media, enhancing waterproofness and corrosion resistance, resulting in a modified basic slurry.

[0039] S2. Slowly add 3.0g of flake zinc-aluminum powder to the modified base slurry described in step S1 while stirring at 600rpm. The average particle size of the flake zinc-aluminum powder is 7μm. As hard alloy particles, the flake zinc-aluminum powder can improve the hardness and wear resistance of the coating and extend the penetration path of corrosive media, thereby improving the durability of the coating. After complete addition, stir at 800rpm for 20min. Then add 4.0g of polymethylphenyl silicone resin and stir for 30min. Next, slowly add cross-linked modified SiO2 aerogel hybrid microspheres at 400rpm. After complete addition, continue stirring for 30min. By embedding the cross-linked modified SiO2 aerogel hybrid microspheres into the modified base slurry network, a large number of uniformly dispersed cross-linked modified SiO2 aerogel hybrid microspheres are formed. O2 aerogel hybrid microspheres form countless tiny insulating units, equivalent to setting up numerous barriers, greatly extending the heat transfer path, effectively blocking heat conduction, and significantly improving thermal insulation performance. As a rigid particle, it is wrapped and fixed by a tough modified base slurry network. Not only are the aerogel microspheres not easily lost due to wear, erosion, or aging, but the embedded aerogel microspheres can also improve the mechanical properties of the modified base slurry, effectively hindering crack propagation. At the same time, the dispersion and embedding of hydrophobic cross-linked modified SiO2 aerogel hybrid microspheres in the modified base slurry not only endows the coating with excellent waterproofness, but also further reduces the infiltration and penetration of moisture and corrosive media through a dense barrier effect, which is conducive to improving the durability of the coating and obtaining a thermal insulation coating.

[0040] Example 2

[0041] This embodiment proposes a heat insulation coating comprising the following components in parts by weight: 20 parts of cross-linked modified SiO2 aerogel hybrid microspheres, 50 parts of modified base slurry, 1 part of flake zinc-aluminum powder, and 2 parts of polymethylphenyl silicone resin.

[0042] Cross-linked coated modified SiO2 aerogel hybrid microspheres comprise the following components in parts by weight: 8 parts glutarate esterified agarose, 3 parts polyvinyl alcohol, 2 parts polyvinyl butyral, 20 parts hydrophobic SiO2 aerogel, and 5 parts methyltrimethoxysilane.

[0043] The modified base slurry is made from the following components in parts by weight: 0.3 parts carbon nanotubes, 0.2 parts graphene oxide, 40 parts epoxy resin, 8 parts barium sulfate, 10 parts graphite powder, 5 parts glass microspheres, 0.1 parts BYK-2150 dispersant, 0.5 parts BYK-333 leveling agent, and 0.2 parts TEGO805 defoamer.

[0044] The preparation method of cross-linked coated modified SiO2 aerogel hybrid microspheres specifically includes the following steps:

[0045] (1) Disperse 4.0 g of agarose in 250 mL of N,N-dimethylformamide solvent, heat to 40 °C and stir magnetically for 3 h. Then add 1.0 g of carbodiimide hydrochloride and 0.8 g of 4-dimethylaminopyridine. Finally, add 2.5 g of glutaric acid. The addition of glutaric acid can not only graft hydrophobic segments (-CO-(CH2)3-COOH) onto the agarose molecules, but also react with the hydroxyl groups on two different agarose molecular chains to form chemical cross-linking points, thus linearizing the agarose molecules. Agarose molecules were linked into a three-dimensional network structure and reacted at 30°C for 3 hours. Then, agarose was precipitated with a 95% ethanol solution and filtered. The washing was repeated twice, and the precipitate was dried in an oven at 40°C for 18 hours. Through glutaric acid modification, hydrophobic segments and a robust cross-linked network were introduced into the agarose, which improved the waterproofness, mechanical durability, and long-term thermal insulation properties of agarose as a coating filler. In addition, it also facilitated the compatibility and affinity with hydrophobic SiO2 aerogel, resulting in glutaric acid-esterified agarose.

[0046] (2) Disperse 0.3g of polyvinyl alcohol and the glutaric acid esterified agarose described in step (1) in an 80% ethanol solution and stir to dissolve in an 80°C water bath. Then add 0.2g of polyvinyl butyral and stir magnetically for 1 hour at a stirring speed of 200 rpm to obtain a polymer solution for later use. Disperse 2.0g of hydrophobic SiO2 aerogel in 30mL of an 80% ethanol solution. The hydrophobic SiO2 aerogel is brand KNF-W50, which has ultra-low density, low thermal conductivity and extremely high thermal conductivity. Porosity can be used as a functional filler in thermal insulation coatings to improve thermal insulation performance. After 30 minutes of ultrasonic assisted stirring, a hydrophobic SiO2 aerogel dispersion was obtained and set aside. Then, the hydrophobic SiO2 aerogel dispersion was slowly added to the polymer solution, and stirred at 80℃ and 700rpm for 0.5 hours. After standing for 10 minutes, a mixed solution was obtained and set aside. 200mL of dimethyl silicone oil was preheated to 80℃ and stirred at 800rpm for 8 minutes. The mixed solution was then slowly added to the pretreated dimethyl silicone oil and stirred for 10 minutes. After stirring for another 30 minutes, the precipitated solid was washed three times sequentially with anhydrous ethanol, 90% ethanol solution, and deionized water. The hydrophobic SiO2 aerogel was modified by coating it with a polymer system of polyvinyl alcohol, glutaric acid-esterified agarose, and polyvinyl butyral. This effectively improved the aerogel's thermal insulation, waterproofing, and durability. The polymer coating on the surface of the hydrophobic SiO2 aerogel did not damage its pore structure, effectively preventing heat transfer and loss. The barrier effect of the coating layer effectively isolated the gas... The partial silanol groups on the gel surface further enhance the overall hydrophobicity. Polyvinyl butyral acts as a toughening agent, forming a flexible polymer coating layer that effectively absorbs and disperses energy, inhibiting the generation and propagation of microcracks. Meanwhile, the hard, hydrophobic SiO2 aerogel core not only ensures hardness and wear resistance but also resists acid and alkali corrosion. The polymer coating layer also helps to isolate corrosive substances from contact with the aerogel core, thus enhancing the overall thermal insulation, waterproofing, and durability, resulting in a coated modified SiO2 aerogel.

[0047] (3) Adjust the pH of 150 mL of 90% ethanol solution to 4.0 using glacial acetic acid. Add 5 mL of methyltrimethoxysilane under magnetic stirring and continue stirring for 30 min to obtain hydrolysate for later use. Then add the coated modified SiO2 aerogel described in step (2) and keep it warm in a 40℃ water bath with low-speed stirring for 6 h at a stirring speed of 100 rpm. Filter the mixture and wash the obtained solid product three times with anhydrous ethanol and deionized water. Soak the washed wet product in tert-butanol three times for 2 h each time. After the replacement, dry it in a vacuum drying oven at 40℃ for 24 h. Methyltrimethoxysilane not only forms Si-OC covalent bonds with the hydroxyl groups of the polymer in the coated modified SiO2 aerogel, but also forms dense Si-O-S through intermolecular self-condensation. The i-three-dimensional network penetrates and reinforces the polymer coating layer. Its unreacted hydrophobic methyl groups are densely arranged on the outermost side, forming a lotus leaf-like surface that makes it difficult for water molecules to wet. At the same time, the stable and strong Si-O-Si chemical bonds greatly enhance the interfacial bonding force between the polymer coating layer and the hydrophobic SiO2 aerogel core, preventing the coating layer from falling off. This makes the filler particles more wear-resistant and compression-resistant. Through the cross-linking treatment of methyltrimethoxysilane, the network of the coated and modified SiO2 aerogel structure is strengthened and hydrophobic groups are introduced, constructing a robust, durable, and superhydrophobic siloxane protective layer. This ensures the integrity and stability of the aerogel nanoporous structure, allowing the thermal insulation performance to be maintained stably for a long time, resulting in cross-linked coated and modified SiO2 aerogel hybrid microspheres.

[0048] This embodiment provides a method for preparing a heat-insulating coating, specifically including the following steps:

[0049] S1. Add 0.3g of carbon nanotubes and 0.1g of BYK-2150 dispersant to 26mL of N,N-dimethylformamide solvent. The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 5nm and a length of 0.5μm. Smaller diameter and shorter length carbon nanotubes are easily bent and entangled, making it difficult to connect with other carbon nanotubes. This prevents the formation of a long-range, highly efficient thermally conductive network by connecting end-to-end. The multi-walled carbon nanotubes have interfaces between layers, and phonons are scattered during interlayer transmission, thus reducing thermal conductivity and enhancing thermal insulation. Sonicate for 30min, then add 0.2g of graphene oxide powder and sonicate for 40min to obtain a composite dispersion of carbon nanotubes and graphene oxide. Set aside. Then, mix the composite dispersion of carbon nanotubes and graphene oxide with 40.0g of epoxy resin, 8.0g of barium sulfate, 10.0g of graphite powder, and 0.5g of B... YK-333 leveling agent and 0.2g TEGO805 defoamer are mixed evenly and ground until the fineness of the slurry is <25μm. 5.0g glass microspheres are slowly added while stirring at 300rpm and stirring continuously for 20min. Finally, the mixture is passed through a 120-mesh sieve. In this process, graphene oxide provides a sheet barrier to block heat conduction and extend the heat path. Carbon nanotubes fill the spaces between the graphene oxide sheets, forming a network structure similar to reinforced concrete. This not only provides basic strength and toughness, reducing the risk of cracks, peeling, and wear, and improving mechanical durability, but also effectively traps heat through the three-dimensional nano-thermal barrier network. Combined with the direct inhibition of gas phase conduction and convection by zero-dimensional glass microspheres, comprehensive inhibition of heat transfer is achieved. At the same time, this tightly filled sheet barrier further extends the tortuous path required for the penetration of water and corrosive media, enhancing waterproofness and corrosion resistance, resulting in a modified basic slurry.

[0050] S2. Slowly add 1.0g of flake zinc-aluminum powder to the modified base slurry described in step S1 while stirring at 300rpm. The average particle size of the flake zinc-aluminum powder is 5μm. As hard alloy particles, the flake zinc-aluminum powder can improve the hardness and wear resistance of the coating and extend the penetration path of corrosive media, thereby improving the durability of the coating. After complete addition, stir at 600rpm for 15min. Then add 2.0g of polymethyl phenyl silicone resin and stir for 20min. Next, slowly add cross-linked modified SiO2 aerogel hybrid microspheres at 200rpm. After complete addition, continue stirring for 20min. By embedding the cross-linked modified SiO2 aerogel hybrid microspheres into the modified base slurry network, a large amount of uniformly dispersed cross-linked modified SiO2 aerogel hybrid microspheres are formed. O2 aerogel hybrid microspheres form countless tiny insulating units, equivalent to setting up numerous barriers, greatly extending the heat transfer path, effectively blocking heat conduction, and significantly improving thermal insulation performance. As a rigid particle, it is wrapped and fixed by a tough modified base slurry network. Not only are the aerogel microspheres not easily lost due to wear, erosion, or aging, but the embedded aerogel microspheres can also improve the mechanical properties of the modified base slurry, effectively hindering crack propagation. At the same time, the dispersion and embedding of hydrophobic cross-linked modified SiO2 aerogel hybrid microspheres in the modified base slurry not only endows the coating with excellent waterproofness, but also further reduces the infiltration and penetration of moisture and corrosive media through a dense barrier effect, which is conducive to improving the durability of the coating and obtaining a thermal insulation coating.

[0051] Example 3

[0052] This embodiment proposes a heat insulation coating comprising the following components in parts by weight: 25 parts of cross-linked modified SiO2 aerogel hybrid microspheres, 55 parts of modified base slurry, 2 parts of flake zinc-aluminum powder, and 3 parts of polymethylphenyl silicone resin.

[0053] Cross-linked coated modified SiO2 aerogel hybrid microspheres comprise the following components in parts by weight: glutaric acid esterified agarose 9 parts, polyvinyl alcohol 4 parts, polyvinyl butyral 3 parts, hydrophobic SiO2 aerogel 25 parts, and methyltrimethoxysilane 7.5 parts.

[0054] The modified base slurry is made from the following components in parts by weight: 0.4 parts carbon nanotubes, 0.3 parts graphene oxide, 45 parts epoxy resin, 9 parts barium sulfate, 12.5 parts graphite powder, 7.5 parts glass microspheres, 0.2 parts BYK-2150 dispersant, 0.65 parts BYK-333 leveling agent, and 0.3 parts TEGO805 defoamer.

[0055] The preparation method of cross-linked coated modified SiO2 aerogel hybrid microspheres specifically includes the following steps:

[0056] (1) Disperse 4.5g of agarose in 250mL of N,N-dimethylformamide solvent, heat to 45℃ and stir magnetically for 3.5h. Then add 1.5g of carbodiimide hydrochloride and 0.9g of 4-dimethylaminopyridine. Finally, add 3.0g of glutaric acid. The addition of glutaric acid can not only graft hydrophobic segments (-CO-(CH2)3-COOH) onto the agarose molecules, but also react with the hydroxyl groups on two different agarose molecular chains to form chemical cross-linking points, thus transforming the linear agarose molecules into a more cohesive and cohesive product. Agarose molecules were linked into a three-dimensional network structure and reacted at 35°C for 3.5 h. Then, agarose was precipitated with 95% ethanol solution and filtered. The washing was repeated 3 times, and the precipitate was dried in an oven at 40°C for 19 h. Through glutaric acid modification, hydrophobic segments and a robust cross-linked network were introduced into the agarose, which improved the waterproofness, mechanical durability and long-term thermal insulation properties of agarose as a coating filler. In addition, it also facilitated the compatibility and affinity with hydrophobic SiO2 aerogel, resulting in glutaric acid-esterified agarose.

[0057] (2) Disperse 0.4g of polyvinyl alcohol and the glutaric acid esterified agarose described in step (1) in an 80% ethanol solution and stir to dissolve in a water bath at 82.5℃. Then add 0.3g of polyvinyl butyral and stir magnetically for 1.5h at a stirring speed of 250rpm to obtain a polymer solution for later use. Disperse 2.5g of hydrophobic SiO2 aerogel in 30mL of an 80% ethanol solution. The hydrophobic SiO2 aerogel is brand KNF-W50, which has ultra-low density, low thermal conductivity and extremely high thermal conductivity. The high porosity allows it to be used as a functional filler in thermal insulation coatings to improve thermal insulation performance. After ultrasonic assisted stirring for 35 minutes, a hydrophobic SiO2 aerogel dispersion was obtained and set aside. Then, the hydrophobic SiO2 aerogel dispersion was slowly added to the polymer solution, and stirred at 82.5℃ and 750 rpm for 0.75 h. After standing for 15 min, a mixed solution was obtained and set aside. 250 mL of dimethyl silicone oil was preheated to 82.5℃ and stirred at 900 rpm for 9 min. The mixed solution was then slowly added to the pretreated dimethyl silicone oil. In oil, the mixture was continuously stirred for 45 minutes. The precipitated solid was washed four times sequentially with anhydrous ethanol, 90% ethanol solution, and deionized water. The hydrophobic SiO2 aerogel was modified by coating it with a polymer system of polyvinyl alcohol, glutaric acid-esterified agarose, and polyvinyl butyral. This effectively improved the aerogel's thermal insulation, waterproofing, and durability. The polymer coating on the surface of the hydrophobic SiO2 aerogel did not damage its pore structure, effectively blocking heat transfer and loss. The barrier effect of the coating layer can... The partial addition of silanol groups on the surface of the aerogel further enhances its overall hydrophobicity. Polyvinyl butyral acts as a toughening agent, forming a flexible polymer coating layer that effectively absorbs and disperses energy, inhibiting the generation and propagation of microcracks. Meanwhile, the hard, hydrophobic SiO2 aerogel core not only ensures hardness and wear resistance but also resists acid and alkali corrosion. The polymer coating layer also helps to isolate corrosive substances from contact with the aerogel core, thus enhancing the overall thermal insulation, waterproofing, and durability, resulting in a coated modified SiO2 aerogel.

[0058] (3) Adjust the pH of 150 mL of 90% ethanol solution to 4.5 using glacial acetic acid. Add 7.5 mL of methyltrimethoxysilane under magnetic stirring and continue stirring for 45 min to obtain a hydrolysate for later use. Then add the coated modified SiO2 aerogel described in step (2) and keep it warm in a 45℃ water bath with low-speed stirring for 9 h at a stirring speed of 150 rpm. Filter the mixture and wash the obtained solid product with anhydrous ethanol and deionized water four times in sequence. Soak the washed wet product in tert-butanol three times for 2.5 h each time. After the replacement, dry it in a vacuum drying oven at 45℃ for 36 h. Methyltrimethoxysilane not only forms Si-OC covalent bonds with the hydroxyl groups of the polymer in the coated modified SiO2 aerogel, but also forms dense Si-O through intermolecular self-condensation. The -Si three-dimensional network penetrates and reinforces the polymer coating layer. Its unreacted hydrophobic methyl groups are densely arranged on the outermost side, forming a lotus leaf-like surface that makes it difficult for water molecules to wet. At the same time, this stable and strong Si-O-Si chemical bond greatly enhances the interfacial bonding force between the polymer coating layer and the hydrophobic SiO2 aerogel core, preventing the coating layer from falling off. This makes the filler particles more wear-resistant and compression-resistant. Through the cross-linking treatment of methyltrimethoxysilane, the network of the coated and modified SiO2 aerogel structure is strengthened and hydrophobic groups are introduced, constructing a robust, durable, and superhydrophobic siloxane protective layer. This ensures the integrity and stability of the aerogel nanoporous structure, allowing the thermal insulation performance to be maintained stably for a long time, resulting in cross-linked coated and modified SiO2 aerogel hybrid microspheres.

[0059] This embodiment provides a method for preparing a heat-insulating coating, specifically including the following steps:

[0060] S1. Add 0.4g of carbon nanotubes and 0.2g of BYK-2150 dispersant to 26mL of N,N-dimethylformamide solvent. The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 7nm and a length of 0.75μm. The smaller diameter and shorter length of the carbon nanotubes make them easier to bend and entangle, making it difficult for them to connect with other carbon nanotubes. This prevents the formation of a long-range, highly efficient thermally conductive network by connecting the ends of the carbon nanotubes. The multi-walled carbon nanotubes have interfaces between their layers, and phonons are scattered during interlayer transmission, thus reducing thermal conductivity and enhancing thermal insulation. Sonicate the mixture for 35min, then add 0.3g of graphene oxide powder and sonicate for 45min to obtain a composite dispersion of carbon nanotubes and graphene oxide. Set aside for later use. Then, mix the composite dispersion of carbon nanotubes and graphene oxide with 45.0g of epoxy resin, 9.0g of barium sulfate, 12.5g of graphite powder, and 0.65g of... BYK-333 leveling agent and 0.3g TEGO805 defoamer are mixed evenly and ground until the fineness of the slurry is <25μm. 7.5g glass microspheres are slowly added while stirring at 450rpm and stirring continuously for 25min. Finally, the mixture is passed through a 120-mesh sieve. In this process, graphene oxide provides a sheet barrier to block heat conduction and extend the heat path. Carbon nanotubes fill the spaces between the graphene oxide sheets, forming a network structure similar to reinforced concrete. This not only provides basic strength and toughness, reducing the risk of cracks, detachment, and wear, and improving mechanical durability, but also effectively traps heat through the three-dimensional nano-thermal barrier network. Combined with the direct inhibition of gas phase conduction and convection by zero-dimensional glass microspheres, comprehensive inhibition of heat transfer is achieved. At the same time, this tightly filled sheet barrier further extends the tortuous path required for the penetration of water and corrosive media, enhancing waterproofness and corrosion resistance, resulting in a modified basic slurry.

[0061] S2. Slowly add 2.0g of flake zinc-aluminum powder to the modified base slurry described in step S1 while stirring at 450rpm. The average particle size of the flake zinc-aluminum powder is 6μm. As hard alloy particles, the flake zinc-aluminum powder can improve the hardness and wear resistance of the coating and extend the penetration path of corrosive media, thereby improving the durability of the coating. After complete addition, stir at 700rpm for 17.5min. Then add 3.0g of polymethyl phenyl silicone resin and stir for 25min. Next, slowly add cross-linked modified SiO2 aerogel hybrid microspheres at 300rpm. After complete addition, continue stirring for 25min. By embedding the cross-linked modified SiO2 aerogel hybrid microspheres into the modified base slurry network, a large number of uniformly dispersed cross-linked modified SiO2 aerogel hybrid microspheres are formed. The iO2 aerogel hybrid microspheres form countless tiny insulating units, equivalent to setting up numerous barriers. This greatly extends the heat transfer path, effectively blocks heat conduction, and significantly improves thermal insulation performance. As a rigid particle, it is encapsulated and fixed by a tough modified base slurry network. Not only are the aerogel microspheres not easily lost due to wear, erosion, or aging, but the embedded aerogel microspheres can also improve the mechanical properties of the modified base slurry, effectively hindering crack propagation. At the same time, the dispersion and embedding of hydrophobic cross-linked modified SiO2 aerogel hybrid microspheres in the modified base slurry not only endows the coating with excellent waterproofness, but also further reduces the infiltration and penetration of moisture and corrosive media through a dense barrier effect, which is conducive to improving the durability of the coating and obtaining a thermal insulation coating.

[0062] Example 4

[0063] This embodiment proposes a heat insulation coating comprising the following components in parts by weight: 30 parts of cross-linked modified SiO2 aerogel hybrid microspheres, 50 parts of modified base slurry, 1 part of flake zinc-aluminum powder, and 4 parts of polymethylphenyl silicone resin.

[0064] Cross-linked coated modified SiO2 aerogel hybrid microspheres comprise the following components in parts by weight: 8 parts glutarate esterified agarose, 5 parts polyvinyl alcohol, 4 parts polyvinyl butyral, 30 parts hydrophobic SiO2 aerogel, and 5 parts methyltrimethoxysilane.

[0065] The modified base slurry is made from the following components in parts by weight: 0.5 parts carbon nanotubes, 0.2 parts graphene oxide, 50 parts epoxy resin, 10 parts barium sulfate, 15 parts graphite powder, 10 parts glass microspheres, 0.3 parts BYK-2150 dispersant, 0.8 parts BYK-333 leveling agent, and 0.4 parts TEGO805 defoamer.

[0066] The preparation method of cross-linked coated modified SiO2 aerogel hybrid microspheres specifically includes the following steps:

[0067] (1) Disperse 5.0 g of agarose in 250 mL of N,N-dimethylformamide solvent, heat to 50 °C and stir magnetically for 3 h. Then add 2.0 g of carbodiimide hydrochloride and 1.0 g of 4-dimethylaminopyridine. Finally, add 2.5 g of glutaric acid. The addition of glutaric acid can not only graft hydrophobic segments (-CO-(CH2)3-COOH) onto the agarose molecules, but also react with the hydroxyl groups on two different agarose molecular chains to form chemical cross-linking points, thus transforming the linear... Agarose molecules were linked into a three-dimensional network structure and reacted at 40℃ for 3 hours. Then, agarose was precipitated with a 95% ethanol solution and filtered. The washing was repeated 4 times, and the precipitate was dried in an oven at 40℃ for 18 hours. Through glutaric acid modification, hydrophobic segments and a robust cross-linked network were introduced into the agarose, which improved the waterproofness, mechanical durability and long-term thermal insulation properties of agarose as a coating filler. In addition, it also facilitated the compatibility and affinity with hydrophobic SiO2 aerogel, resulting in glutaric acid-esterified agarose.

[0068] (2) Disperse 0.5g of polyvinyl alcohol and the glutaric acid esterified agarose mentioned in step (1) in an 80% ethanol solution and stir to dissolve in an 85°C water bath. Then add 0.4g of polyvinyl butyral and stir magnetically for 1 hour at a stirring speed of 300 rpm to obtain a polymer solution for later use. Disperse 3.0g of hydrophobic SiO2 aerogel in 30mL of an 80% ethanol solution. The hydrophobic SiO2 aerogel is brand KNF-W50, which has ultra-low density, low thermal conductivity and extremely high porosity. The porosity can be used as a functional filler in thermal insulation coatings to improve thermal insulation performance. After ultrasonic assisted stirring for 30 minutes, a hydrophobic SiO2 aerogel dispersion was obtained and set aside. Then, the hydrophobic SiO2 aerogel dispersion was slowly added to the polymer solution and stirred at 85℃ and 800rpm for 0.5h. After standing for 10min, a mixed solution was obtained and set aside. 300mL of dimethyl silicone oil was preheated to 85℃ and stirred at 1000rpm for 8min. The mixed solution was then slowly added to the pretreated dimethyl silicone oil and stirred for 10min. After stirring for another 30 minutes, the precipitated solid was washed five times successively with anhydrous ethanol, 90% ethanol solution, and deionized water. The hydrophobic SiO2 aerogel was modified by coating it with a polymer system of polyvinyl alcohol, glutaric acid-esterified agarose, and polyvinyl butyral. This effectively improved the aerogel's thermal insulation, waterproofing, and durability. The polymer coating on the surface of the hydrophobic SiO2 aerogel did not damage its pore structure, effectively blocking heat transfer and loss. The barrier effect of the coating layer effectively isolated the gas... The partial silanol groups on the gel surface further enhance the overall hydrophobicity. Polyvinyl butyral acts as a toughening agent, forming a flexible polymer coating layer that effectively absorbs and disperses energy, inhibiting the generation and propagation of microcracks. Meanwhile, the hard, hydrophobic SiO2 aerogel core not only ensures hardness and wear resistance but also resists acid and alkali corrosion. The polymer coating layer also helps to isolate corrosive substances from contact with the aerogel core, thus enhancing the overall thermal insulation, waterproofing, and durability, resulting in a coated modified SiO2 aerogel.

[0069] (3) Adjust the pH of 150 mL of 90% ethanol solution to 5.0 using glacial acetic acid. Add 5 mL of methyltrimethoxysilane under magnetic stirring and continue stirring for 30 min to obtain hydrolysate for later use. Then add the coated modified SiO2 aerogel described in step (2) and keep it warm in a 50℃ water bath with low-speed stirring for 6 h at a stirring speed of 200 rpm. Filter the mixture and wash the obtained solid product with anhydrous ethanol and deionized water 5 times in sequence. Soak the washed wet product in tert-butanol 3 times for 2 h each time. After the replacement, dry it in a vacuum drying oven at 50℃ for 24 h. Methyltrimethoxysilane not only forms Si-OC covalent bonds with the hydroxyl groups of the polymer in the coated modified SiO2 aerogel, but also forms dense Si-O-S through intermolecular self-condensation. The i-three-dimensional network penetrates and reinforces the polymer coating layer. Its unreacted hydrophobic methyl groups are densely arranged on the outermost side, forming a lotus leaf-like surface that makes it difficult for water molecules to wet. At the same time, the stable and strong Si-O-Si chemical bonds greatly enhance the interfacial bonding force between the polymer coating layer and the hydrophobic SiO2 aerogel core, preventing the coating layer from falling off. This makes the filler particles more wear-resistant and compression-resistant. Through the cross-linking treatment of methyltrimethoxysilane, the network of the coated and modified SiO2 aerogel structure is strengthened and hydrophobic groups are introduced, constructing a robust, durable, and superhydrophobic siloxane protective layer. This ensures the integrity and stability of the aerogel nanoporous structure, allowing the thermal insulation performance to be maintained stably for a long time, resulting in cross-linked coated and modified SiO2 aerogel hybrid microspheres.

[0070] This embodiment provides a method for preparing a heat-insulating coating, specifically including the following steps:

[0071] S1. Add 0.5g of carbon nanotubes and 0.3g of BYK-2150 dispersant to 26mL of N,N-dimethylformamide solvent. The carbon nanotubes are multi-walled carbon nanotubes with a diameter of 9nm and a length of 1.0μm. Smaller diameter and shorter length carbon nanotubes are easily bent and entangled, making it difficult to connect with other carbon nanotubes. This prevents the formation of a long-range, highly efficient thermally conductive network by connecting end-to-end. The multi-walled carbon nanotubes have interfaces between layers, and phonons are scattered during interlayer transmission, thus reducing thermal conductivity and enhancing thermal insulation. Sonicate for 30min, then add 0.2g of graphene oxide powder and sonicate for 40min to obtain a composite dispersion of carbon nanotubes and graphene oxide. Set aside. Then, mix the composite dispersion of carbon nanotubes and graphene oxide with 50.0g of epoxy resin, 10.0g of barium sulfate, 15.0g of graphite powder, and 0.8g of B... YK-333 leveling agent and 0.4g TEGO805 defoamer are mixed evenly and ground until the fineness of the slurry is <25μm. 10.0g glass microspheres are slowly added while stirring at 600rpm, and stirring is continued for 20min. Finally, the mixture is passed through a 120-mesh sieve. In this process, graphene oxide provides a sheet barrier to block heat conduction and extend the heat path. Carbon nanotubes fill the spaces between the graphene oxide sheets, forming a network structure similar to reinforced concrete. This not only provides basic strength and toughness, reducing the risk of cracks, detachment, and wear, and improving mechanical durability, but also effectively traps heat through the three-dimensional nano-thermal barrier network. Combined with the direct inhibition of gas phase conduction and convection by zero-dimensional glass microspheres, comprehensive inhibition of heat transfer is achieved. At the same time, this tightly filled sheet barrier further extends the tortuous path required for the penetration of water and corrosive media, enhancing waterproofness and corrosion resistance, resulting in a modified basic slurry.

[0072] S2. Slowly add 1.0g of flake zinc-aluminum powder to the modified base slurry described in step S1 while stirring at 600rpm. The average particle size of the flake zinc-aluminum powder is 7μm. As hard alloy particles, the flake zinc-aluminum powder can improve the hardness and wear resistance of the coating and extend the penetration path of corrosive media, thereby improving the durability of the coating. After complete addition, stir at 800rpm for 15min. Then add 4.0g of polymethylphenyl silicone resin and stir for 20min. Next, slowly add cross-linked modified SiO2 aerogel hybrid microspheres at 400rpm. After complete addition, continue stirring for 20min. By embedding the cross-linked modified SiO2 aerogel hybrid microspheres into the modified base slurry network, a large number of uniformly dispersed cross-linked modified SiO2 aerogel hybrid microspheres are formed. O2 aerogel hybrid microspheres form countless tiny insulating units, equivalent to setting up numerous barriers, greatly extending the heat transfer path, effectively blocking heat conduction, and significantly improving thermal insulation performance. As a rigid particle, it is wrapped and fixed by a tough modified base slurry network. Not only are the aerogel microspheres not easily lost due to wear, erosion, or aging, but the embedded aerogel microspheres can also improve the mechanical properties of the modified base slurry, effectively hindering crack propagation. At the same time, the dispersion and embedding of hydrophobic cross-linked modified SiO2 aerogel hybrid microspheres in the modified base slurry not only endows the coating with excellent waterproofness, but also further reduces the infiltration and penetration of moisture and corrosive media through a dense barrier effect, which is conducive to improving the durability of the coating and obtaining a thermal insulation coating.

[0073] Comparative Example 1

[0074] This comparative example provides a thermal insulation coating, which differs from Example 1 in that the cross-linked coated modified SiO2 aerogel hybrid microspheres do not contain glutaric acid and are not modified with agarose; the preparation method of the cross-linked coated modified SiO2 aerogel hybrid microspheres does not include step (1), and agarose is directly added in step (2); the preparation method of the thermal insulation coating is the same as that of Example 1.

[0075] Comparative Example 2

[0076] This comparative example provides a thermal insulation coating, which differs from Example 1 in that the cross-linked coated modified SiO2 aerogel hybrid microspheres do not contain methyltrimethoxysilane; the preparation method of the cross-linked coated modified SiO2 aerogel hybrid microspheres does not include step (3); the preparation method of the thermal insulation coating is the same as that of Example 1.

[0077] Comparative Example 3

[0078] This comparative example provides a thermal insulation coating, which differs from Example 1 in that the modified base slurry does not contain carbon nanotubes or graphene oxide; the preparation method of the cross-linked coated modified SiO2 aerogel hybrid microspheres is the same as in Example 1; and carbon nanotubes or graphene oxide powder are not added in step S1 of the preparation method of the thermal insulation coating.

[0079] Experimental Example 1

[0080] Thermal insulation test

[0081] Test samples: thermal insulation coatings prepared in Examples 1-4 and Comparative Examples 1-3.

[0082] Test method: The test sample was evenly coated on a ceramic fiber board (330×300×3mm) to make a sample with a coating thickness of 2±0.1mm. At room temperature of 27℃, the sample was placed vertically at the opening of a 250℃ muffle furnace. Appropriate heat insulation baffles were added around the furnace opening and the sample. The coating was then placed facing the muffle furnace. The temperature of the back of the coating was measured using an infrared thermometer. The initial test temperature T1 was recorded. After 30 minutes, the test was repeated and recorded as T2. Ten points were taken for each test, and the average value was calculated. The temperature difference (℃) between T2 and T1 was then calculated. The smaller the temperature difference, the better the thermal insulation performance.

[0083] Figure 1 The figure shows the temperature difference results for Examples 1-4 and Comparative Examples 1-3. As shown, the temperature difference for Examples 1-4 is 20-28℃, indicating good thermal insulation performance. The temperature difference for Comparative Examples 1-3 is 37-46℃, indicating average thermal insulation performance. The cross-linked coated modified SiO2 aerogel hybrid microspheres in Comparative Example 1 do not contain glutaric acid and are not modified with agarose. Agarose will directly penetrate and block the pore structure of the hydrophobic SiO2 aerogel, resulting in average thermal insulation performance. The cross-linked coated modified SiO2 aerogel hybrid microspheres in Comparative Example 2 do not contain methyltrimethoxysilane, which cannot penetrate and reinforce the polymer coating layer, thus hindering structural reinforcement, increasing the risk of collapse, and failing to effectively maintain the nanoporous structure, resulting in average thermal insulation performance. The modified base slurry in Comparative Example 3 does not contain carbon nanotubes or graphene oxide, thus failing to form a three-dimensional nanothermal barrier network, which is detrimental to the inhibition of heat transfer, resulting in average thermal insulation performance.

[0084] Experiment Example 2

[0085] Waterproofing test

[0086] Test samples: thermal insulation coatings prepared in Examples 1-4 and Comparative Examples 1-3.

[0087] Test method: The test sample is evenly coated on a ceramic fiber board (330×300×3mm) to make a sample with a coating thickness of 2±0.1mm. After drying, the sample is weighed and then the water absorption rate is tested according to the method of HG / T3344-2012. The sample is sealed with a 1:1 mixture of paraffin and rosin. The sealed sample is placed vertically in a water tank, ensuring that 2 / 3 of the sample area is completely immersed in water and does not come into contact with the water tank wall. After 48 hours, the sample is removed and weighed. The water absorption rate (%) is then obtained.

[0088] Figure 2 The figures show the water absorption rates of Examples 1-4 and Comparative Examples 1-3. As shown, the water absorption rate of Examples 1-4 was 2.6-4.2%, indicating good water resistance; the water absorption rate of Comparative Examples 1-3 was 8.8-13.4%, indicating moderate water resistance. The cross-linked modified SiO2 aerogel microspheres of Comparative Example 1 did not contain glutaric acid or undergo agarose modification, making it impossible to introduce hydrophobic segments and construct a cross-linked network in the agarose. This hindered further hydrophobic coating modification of the hydrophobic SiO2 aerogel, resulting in moderate water resistance. The cross-linked modified SiO2 aerogel microspheres of Comparative Example 2 did not contain methyltrimethoxysilane, making it impossible to construct a superhydrophobic siloxane protective layer through cross-linking curing and the introduction of hydrophobic groups, resulting in moderate water resistance. The modified base slurry of Comparative Example 3 did not contain carbon nanotubes or graphene oxide, making it impossible to form a dense, filled sheet barrier, which hindered the extension of the water entry path, resulting in moderate water resistance.

[0089] Experimental Example 3

[0090] Durability test

[0091] Test samples: thermal insulation coatings prepared in Examples 1-4 and Comparative Examples 1-3.

[0092] Test methods: (1) Wear resistance: The test sample was uniformly coated on a ceramic fiber board (330×300×3mm) to make a sample with a coating thickness of 2±0.1mm. After complete curing, the wear performance of the sample was tested using a UMT-Tribolbab ball-disc friction tester. A Si3N4 ball with a diameter of 6.35mm was used as the friction pair material. The load (F) of the sliding test was 10N, the rotation speed (R) was 364r / min, the rotation radius (d) was 3.5mm, and the test time (T) was 60min. The total wear volume (Vm) of the coating was measured by an Alphastep P-7 probe contact profilometer, and the volume wear rate (mm) of the coating was calculated using the following formula. 3 / N·m):

[0093] Volumetric wear rate (mm) 3 / N·m)=Vm / (3.14×F×d×R×T;

[0094] (2) Corrosion resistance: The test sample was evenly coated onto a ceramic fiber board (330×300×3mm) to form a sample with a coating thickness of 2±0.1mm. The edges were sealed with salt spray resistant tape. After complete curing, in accordance with GB / T2423.17-93, a YWX / Q-150 salt spray test chamber was used to prepare a 5% NaCl aqueous solution and adjust the pH to 7 as the solution for the salt spray test. The temperature was 35℃ and the salt spray deposition was 1.5mL / 80cm. 3 •h, observe and calculate the percentage of the failed area of ​​the sample after 1000h, where the failed area includes areas that are abnormally damaged such as blistering, peeling, and discoloration.

[0095] Figure 3 The graph shows the volumetric wear rate results for Examples 1-4 and Comparative Examples 1-3; Figure 4 The graph shows the failure area percentage results for Examples 1-4 and Comparative Examples 1-3; as shown. Figure 3 The volumetric wear rate of Examples 1-4 was 1.3-2.5 × 10⁻⁴. -5 mm 3 / N·m indicates strong wear resistance; the volumetric wear rate of comparative examples 1-3 was 4.8-8.3×10 -5 mm 3 / N·m indicates that the wear resistance is average; such as Figure 4 The failure area ratio of Examples 1-4 was 2.0-4.6%, indicating strong corrosion resistance; the failure area ratio of Comparative Examples 1-3 was 10.8-18.5%, indicating moderate corrosion resistance. The cross-linked coated modified SiO2 aerogel hybrid microspheres of Comparative Example 1 did not contain glutaric acid and were not modified with agarose. The direct addition of agarose is detrimental to the structural stability of the hydrophobic SiO2 aerogel and cannot exert the resistance and delay effect of the nanoporous structure against acid and alkali corrosion, thus increasing the risk of wear and corrosion, resulting in poor durability. The cross-linked coated modified SiO2 aerogel hybrid microspheres of Comparative Example 2 did not contain methyltrimethoxysilane, and therefore could not form a dense S... The i-O-Si three-dimensional network penetrates and reinforces the polymer coating layer, increasing the risk of coating layer detachment and wear. It also prevents the dense arrangement of hydrophobic methyl groups on the outermost layer, which is not conducive to reducing the penetration channels of corrosive media. Therefore, it cannot effectively reduce wear and inhibit corrosion, resulting in poor durability. The modified base slurry in Comparative Example 3 does not contain carbon nanotubes or graphene oxide, so it cannot form a nano three-dimensional network to adsorb and entangle on the surface of cross-linked coated modified SiO2 aerogel hybrid microspheres, increasing the risk of wear and detachment. It also cannot form a tight filled sheet barrier, which is not conducive to extending the tortuous path required for corrosive media penetration. Therefore, it is not conducive to reducing wear and corrosion, resulting in poor durability.

[0096] The above experimental results show that the thermal insulation, waterproofing, and durability of Examples 1-4 of the present invention are significantly better than those of Comparative Examples 1-3. Among them, Example 1, which uses cross-linked coated modified SiO2 aerogel hybrid microspheres and modified base slurry, has better thermal insulation, waterproofing, wear resistance, and corrosion resistance. The cross-linked coated modified SiO2 aerogel hybrid microspheres are uniformly embedded in the modified base slurry network, forming numerous tiny thermal insulation units in the three-dimensional nano-thermal barrier network. This effectively inhibits and blocks heat conduction, improving thermal insulation performance. At the same time, it also endows the coating with strong hydrophobicity and impermeability, significantly enhancing waterproofing performance. Furthermore, the three-dimensional nano-network fixes and encapsulates the cross-linked coated modified SiO2 aerogel hybrid microspheres, which not only improves the overall mechanical durability and reduces the risk of cracking, peeling, and wear, but also further reduces the intrusion and penetration of corrosive media with a dense barrier effect, which is beneficial to improving the durability of the coating.

[0097] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

[0098] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A heat-insulating coating, characterized in that: The thermal insulation coating comprises the following components in parts by weight: 20-30 parts of cross-linked modified SiO2 aerogel hybrid microspheres, 50-60 parts of modified base slurry, 1-3 parts of flake zinc-aluminum powder, and 2-4 parts of polymethyl phenyl silicone resin; the cross-linked modified SiO2 aerogel hybrid microspheres comprise the following components in parts by weight: 8-10 parts of glutaric acid esterified agarose, 3-5 parts of polyvinyl alcohol, 2-4 parts of polyvinyl butyral, and 20-30 parts of hydrophobic SiO2 aerogel. The modified base slurry is composed of the following components in parts by weight: carbon nanotubes 0.3-0.5 parts, graphene oxide 0.2-0.4 parts, epoxy resin 40-50 parts, barium sulfate 8-10 parts, graphite powder 10-15 parts, glass microspheres 5-10 parts, BYK-2150 dispersant 0.1-0.3 parts, BYK-333 leveling agent 0.5-0.8 parts, and TEGO805 defoamer 0.2-0.4 parts.

2. A method for preparing the thermal insulation coating according to claim 1, characterized in that: Specifically, the following steps are included: S1. Add 0.3-0.5g of carbon nanotubes and 0.1-0.3g of BYK-2150 dispersant to 26mL of N,N-dimethylformamide solvent, and sonicate for 30-40min. Then add 0.2-0.4g of graphene oxide powder and sonicate for 40-50min to obtain a composite dispersion of carbon nanotubes and graphene oxide, which is set aside. Then, mix the composite dispersion of carbon nanotubes and graphene oxide with 40.0-50.0... Mix 8.0-10.0g epoxy resin, 10.0-15.0g barium sulfate, 0.5-0.8g graphite powder, 0.2-0.4g BYK-333 leveling agent, and 0.2-0.4g TEGO805 defoamer evenly, grind until the fineness of the slurry is <25μm, slowly add 5.0-10.0g glass microspheres while stirring at 300-600rpm, continue stirring for 20-30min, and finally pass through a 120-mesh sieve to obtain the modified base slurry; S2. Slowly add the modified base slurry described in step S1 to the flake zinc-aluminum powder while stirring at 300-600 rpm. After it is completely added, stir at 600-800 rpm for 15-20 minutes. Then add 2.0-4.0 g of polymethylphenyl silicone resin and stir for 20-30 minutes. Next, slowly add the cross-linked coated modified SiO2 aerogel hybrid microspheres at 200-400 rpm. After it is completely added, continue stirring for 20-30 minutes to obtain the heat insulation coating.

3. The method for preparing the heat-insulating coating according to claim 2, characterized in that: In step S1, the carbon nanotubes are multi-walled carbon nanotubes with a diameter of 5-9 nm and a length of 0.5-1.0 μm.

4. The method for preparing the heat-insulating coating according to claim 3, characterized in that: In step S2, the amount of flaky zinc-aluminum powder added is 1.0-3.0g, and the average particle size is 5-7μm.

5. The method for preparing the heat-insulating coating according to claim 4, characterized in that: The preparation method of the cross-linked coated modified SiO2 aerogel hybrid microspheres specifically includes the following steps: (1) Disperse 4.0-5.0g of agarose in 250mL of N,N-dimethylformamide solvent, heat to 40-50℃ and stir magnetically at the same time for 3-4h. Then add 1.0-2.0g of carbodiimide hydrochloride and 0.8-1.0g of 4-dimethylaminopyridine. Finally add glutaric acid and react at 30-40℃ for 3-4h. Then precipitate the agarose with 95% ethanol solution and filter. Repeat washing 2-4 times. Dry the precipitate in an oven at 40℃ for 18-20h to obtain glutaric acid esterified agarose. (2) Disperse 0.3-0.5g of polyvinyl alcohol and the glutaric acid esterified agarose described in step (1) in an 80% ethanol solution and stir to dissolve in a water bath at 80-85℃. Then add 0.2-0.4g of polyvinyl butyral and stir magnetically for 1-2 hours at a stirring speed of 200-300 rpm to obtain a polymer solution for later use. Disperse 2.0-3.0g of hydrophobic SiO2 aerogel in 30mL of an 80% ethanol solution and sonicate for 30-40 minutes to obtain a hydrophobic SiO2 aerogel dispersion for later use. Then, dissolve the hydrophobic SiO2... The aerogel dispersion was slowly added to the polymer solution and stirred at 80-85℃ and 700-800rpm for 0.5-1h. After standing for 10-20min, the mixture was prepared for use. 200-300mL of dimethyl silicone oil was preheated to 80-85℃ and stirred at 800-1000rpm for 8-10min. The mixture was then slowly added to the pretreated dimethyl silicone oil and stirred for 30-60min. The precipitated solid was washed 3-5 times with anhydrous ethanol, 90% ethanol solution and deionized water to obtain the coated modified SiO2 aerogel. (3) Adjust the pH of 150 mL of 90% ethanol solution to 4.0-5.0 with glacial acetic acid. Add 5-10 mL of methyltrimethoxysilane under magnetic stirring and continue stirring for 30-60 min to obtain hydrolysate for later use. Then add the coated modified SiO2 aerogel described in step (2) and keep it warm in a water bath at 40-50℃ with low-speed stirring for 6-12 h at a stirring speed of 100-200 rpm. Filter the product and wash the obtained solid product with anhydrous ethanol and deionized water 3-5 times in sequence. Soak the washed wet product in tert-butanol for 3 times for 2-3 h each time. After replacement, put it in a vacuum drying oven at 40-50℃ and dry for 24-48 h to obtain cross-linked coated modified SiO2 aerogel hybrid microspheres.

6. The method for preparing the heat-insulating coating according to claim 5, characterized in that: In step (1), the amount of glutaric acid added is 2.5-3.5g.

7. The method for preparing the heat-insulating coating according to claim 6, characterized in that: In step (2), the hydrophobic SiO2 aerogel is grade KNF-W50.

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