Nanometer aerogel thermal insulation coating and preparation method thereof

Abstract

This invention relates to the field of coating technology and proposes a nano-aerogel thermal insulation coating and its preparation method. The nano-aerogel thermal insulation coating comprises the following components in parts by weight: 35-50 parts silicate binder, 10-30 parts polymer-modified silica aerogel, 20-40 parts filler, and 1.5-8 parts additives; the polymer includes ethylene-vinyl alcohol copolymer. This technical solution solves the problem of insufficient thermal insulation performance of aerogel coatings in related technologies.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a nano-aerogel heat-insulating coating and its preparation method. Background Technology

[0002] Aerogel thermal insulation coatings are key protective materials in industrial high-temperature equipment, building energy conservation, and high-end manufacturing. Their thermal insulation performance directly determines the operational safety, service life, and energy-saving effect of equipment. Currently, the core problem of insufficient thermal insulation performance in conventional aerogel thermal insulation coatings has become a constraint on their application in high-end fields.

[0003] Existing products mostly use single fillers and simple compounding processes, resulting in simple insulation structures, low thermal barrier efficiency, and thermal conductivity generally exceeding 0.03 W / (m²). Inorganic thermal insulation fillers (K) are difficult to achieve ultra-low thermal conductivity. Furthermore, they tend to agglomerate and exhibit poor dispersion stability within the system, leading to defects such as uneven porosity, cracking, and peeling after coating formation, significantly reducing the thermal insulation effect.

[0004] In high-temperature environments such as metallurgy and kilns, the thermal insulation performance of coatings rapidly degrades, making it difficult to meet the requirements for long-term, stable high-temperature thermal insulation. Due to insufficient thermal insulation performance, existing aerogel coatings cannot be adapted to high-end high-temperature protection scenarios, limiting their promotion and application in industrial high-temperature energy conservation and special protection fields. Summary of the Invention

[0005] This invention proposes a nano-aerogel thermal insulation coating and its preparation method, which solves the problem of insufficient thermal insulation performance of aerogel coatings in related technologies.

[0006] The technical solution of the present invention is as follows: This invention proposes a nano-aerogel thermal insulation coating, comprising the following components in parts by weight: The composition includes 35-50 parts of silicate binder, 10-30 parts of polymer-modified silica aerogel, 20-40 parts of filler, and 1.5-8 parts of additives; the polymer includes ethylene-vinyl alcohol copolymer.

[0007] As a further technical solution, the polymer content in the polymer-modified silica aerogel is 12%~14%.

[0008] As a further technical solution, the preparation method of the polymer-modified silica aerogel includes the following steps: The polymer is dissolved to obtain a solution; The silicon source was hydrolyzed, ammonia was added for catalysis, and the mixture was allowed to stand to obtain gel A; After the gel A ages, solvent exchange is performed to obtain gel B; The gel B was immersed in the solution, the phases were separated, and solvent exchange was performed to obtain the modified gel. The modified gel was dried and pulverized to obtain polymer-modified silica aerogel.

[0009] As a further technical solution, the silicon source includes tetraethyl orthosilicate.

[0010] As a further technical solution, the solvent used for dissolution is a mixture of isopropanol and water; The mass-to-volume ratio of the polymer to the mixed solvent is 1g:60~70mL.

[0011] As a further technical solution, the hydrolysis step specifically involves mixing a silicon source with an ethanol and hydrochloric acid solution to obtain a hydrolysate. The mass ratio of the silicon source, ethanol, and hydrochloric acid solution is 1.1~1.3:1:0.1; The volume ratio of the hydrolysate to the ammonia solution is 4:1; The aging time is 24 hours, and the temperature is 25~30℃; The solvent exchange time is 24 hours; The soaking temperature is 65~70℃, and the soaking time is 2.5~3.5 days; The phase separation temperature is 25~30℃; The drying process is supercritical carbon dioxide drying.

[0012] As a further technical solution, the packing includes at least one of spherical packing and fibrous packing; The spherical filler includes at least one of hollow glass microspheres, zirconium oxide, and alumina; The fibrous filler includes at least one of mullite fiber and aluminosilicate fiber; Preferably, the spherical filler comprises hollow glass microspheres, zirconium oxide, and alumina; the fibrous filler comprises mullite fibers.

[0013] As a further technical solution, the additives include at least one of leveling agents, suspending agents, and defoamers; Preferably, the additive comprises the following components in parts by weight: 0.5 to 3 parts of leveling agent and 1 to 5 parts of suspending agent.

[0014] As a further technical solution, the leveling agent includes a polyether-modified polysiloxane leveling agent; The suspending agent includes at least one of attapulgite and bentonite.

[0015] As a further technical solution, the silicate binder includes a potassium sodium silicate binder with a solid content of 25% to 35%.

[0016] As a further technical solution, the preparation method of the potassium sodium silicate binder includes the following steps: mixing potassium silicate, sodium silicate and water, aging, cooling, and obtaining potassium sodium silicate binder.

[0017] In this invention, a potassium sodium silicate composite silicate solution is used as the inorganic binder phase, which does not decompose or fail at high temperatures. Combined with the high-temperature structural stabilizing effect of nano-zirconia, the high-temperature stability of the coating is improved. Modified aerogel, hollow glass microspheres and other composite heat-insulating fillers are used, which combine the dual effects of nanoporous heat insulation and microporous heat insulation to significantly reduce the thermal conductivity. The combined use of inorganic leveling agents and suspending agents takes into account both the leveling properties of the coating during application and its storage stability. It shows no sedimentation or stratification after being stored at room temperature for 3 months or more.

[0018] As a further technical solution, the mass ratio of potassium silicate to sodium silicate is 1:0.5~1.2; The mixing temperature is 40~60℃, the rotation speed is 200~300rpm, and the time is 30~60min; The ripening time is 1 to 3 hours.

[0019] As a further technical solution, the polymer-modified silica aerogel also includes nano-montmorillonite, with the content of nano-montmorillonite being 5%~8%.

[0020] This invention also discloses a method for preparing a nano-aerogel thermal insulation coating, comprising the following steps: The silicate binder and filler are mixed, and then polymer-modified silica aerogel and additives are added and mixed further to obtain a nano-aerogel heat insulation coating.

[0021] As a further technical solution, the filler is also pre-crushed and sieved.

[0022] As a further technical solution, the nano-aerogel thermal insulation coating is also filtered through a 250-mesh filter and subjected to vacuum degassing treatment to finally obtain the finished coating.

[0023] In this invention, the raw materials are finely pretreated by airflow pulverization, ultrasonic vibration, and sieving to remove large particulate impurities and ensure the uniformity of powder particle size; the pre-dispersion process effectively solves the problem of agglomeration of inorganic fillers in silicate solution, so that each component is fully dispersed; vacuum degassing treatment removes air bubbles from the slurry, avoids defects such as pinholes and shrinkage cavities after coating film formation, and improves the density of the coating.

[0024] The nano-aerogel thermal insulation coating prepared by this invention can be used on a variety of substrates such as metals, ceramics, and refractory materials; it can be applied to metallurgical kilns, high-temperature power equipment, industrial high-temperature pipelines, aerospace high-temperature components, and high-temperature structural parts of high-end equipment.

[0025] The raw materials used in this invention are all commercially available materials, and the preparation equipment is conventional industrial dispersion, crushing and filtration equipment. There are no special customized equipment requirements. The process steps are simple, the parameters are easy to control, it is suitable for large-scale continuous industrial production, the production cost is controllable, and it has extremely high industrial promotion value.

[0026] The working principle and beneficial effects of this invention are as follows: In this invention, ethylene-vinyl alcohol copolymer-modified silica aerogel is used as the core component of the coating, significantly improving its thermal insulation performance. The ethylene-vinyl alcohol copolymer in situ modifies the silica aerogel, effectively inhibiting aerogel particle agglomeration and maintaining a complete nanoporous network structure within the coating. This retains high porosity and a low thermal conductivity framework, significantly reducing solid-state heat conduction. Simultaneously, the copolymer forms a uniform coating layer on the aerogel surface, optimizing the interfacial bonding between components and reducing interfacial thermal resistance and heat convection loss. Through the synergistic enhancement of pore insulation, interfacial barrier, and heat conduction inhibition, the coating's thermal conductivity is significantly reduced, resulting in a substantial improvement in thermal insulation performance. Furthermore, the coating structure is denser and more stable, achieving long-lasting and highly efficient thermal insulation. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] The hollow glass microspheres are low-alkalinity hollow glass microspheres with a particle size of 50 μm and a floating rate of ≥90%; the zirconium oxide is monoclinic nano-zirconia powder with a particle size of 100 nm and a purity of ≥99.5%; the alumina has a particle size of 25 μm; the mullite fiber has a length of 30 μm; the ethylene-vinyl alcohol copolymer is model VH2704RB; and the polyether-modified polysiloxane leveling agent is model CZ-L4627.

[0029] Example 1 Nano-aerogel thermal insulation coating comprises the following components in parts by weight: 35 parts of potassium sodium silicate binder, 10 parts of ethylene-vinyl alcohol copolymer modified silica aerogel, 20 parts of filler, 0.5 parts of polyether modified polysiloxane leveling agent, and 1 part of attapulgite clay; the filler is hollow glass microspheres, zirconium oxide, alumina and mullite fibers in a mass ratio of 5:1:1:1. A method for preparing ethylene-vinyl alcohol copolymer modified silica aerogel includes the following steps: The ethylene-vinyl alcohol copolymer was dissolved in a 75% (v / v) aqueous solution of isopropanol to obtain a solution. Tetraethyl orthosilicate, ethanol, and hydrochloric acid solution (0.05M) were mixed and hydrolyzed at a mass ratio of 1.1:1:0.1 to obtain a hydrolysate. Ammonia water (0.3M) (volume ratio of hydrolysate to ammonia water was 4:1) was added to the hydrolysate for catalysis. After standing for 24 hours, gel A was obtained. Gel A was aged at 25°C for 24 hours, and then subjected to solvent (isopropanol) exchange for 24 hours to obtain gel B; Gel B was immersed in the solution (65℃) for 3.5 days, phase separation was performed at 25℃, and solvent (isopropanol) exchange was carried out for 24 hours to obtain the modified gel. The modified gel was subjected to supercritical carbon dioxide drying and pulverized to obtain ethylene-vinyl alcohol copolymer modified silica aerogel (the content of ethylene-vinyl alcohol copolymer in the ethylene-vinyl alcohol copolymer modified silica aerogel was 12wt%). The preparation method of potassium sodium silicate binder includes the following steps: potassium silicate, sodium silicate and water are mixed at 40°C and 200 rpm for 60 min, matured for 1 h, and cooled to obtain potassium sodium silicate binder (solid content 25%); the mass ratio of potassium silicate to sodium silicate is 1:0.5; The preparation method of nano-aerogel thermal insulation coating includes the following steps: The filler was pre-treated by crushing and then sieved through a 300-mesh ultrasonic vibrating screen (vibration frequency 30kHz) to obtain pre-treated filler. The potassium sodium silicate binder and the pre-treated filler were mixed to obtain a preliminary mixture. Ethylene-vinyl alcohol copolymer modified silica aerogel, polyether modified polysiloxane leveling agent, and attapulgite clay were added and mixed further. The mixture was filtered through a 250-mesh filter and degassed in a vacuum degassing machine (-0.09MPa vacuum, 80rpm) for 15 minutes to obtain a nano aerogel thermal insulation coating.

[0030] Example 2 Nano-aerogel thermal insulation coating comprises the following components in parts by weight: 50 parts of potassium sodium silicate binder, 30 parts of ethylene-vinyl alcohol copolymer modified silica aerogel, 40 parts of filler, 3 parts of polyether modified polysiloxane leveling agent, and 5 parts of attapulgite; the filler is hollow glass microspheres, zirconium oxide, alumina and mullite fiber in a mass ratio of 5:1:1:1. A method for preparing ethylene-vinyl alcohol copolymer modified silica aerogel includes the following steps: The ethylene-vinyl alcohol copolymer was dissolved in a 75% (v / v) aqueous solution of isopropanol to obtain a solution. Tetraethyl orthosilicate, ethanol, and hydrochloric acid solution (0.05M) were mixed and hydrolyzed at a mass ratio of 1.3:1:0.1 to obtain a hydrolysate. Ammonia water (0.3M) (volume ratio of hydrolysate to ammonia water was 4:1) was added to the hydrolysate for catalysis. After standing for 24 hours, gel A was obtained. Gel A was aged at 30°C for 24 hours, and then subjected to solvent (isopropanol) exchange for 24 hours to obtain gel B; Gel B was immersed in a dissolving solution (70℃) for 2.5 days, phase separation was performed at 30℃, and solvent (isopropanol) exchange was carried out for 24 hours to obtain the modified gel. The modified gel was subjected to supercritical carbon dioxide drying and pulverized to obtain ethylene-vinyl alcohol copolymer modified silica aerogel (the content of ethylene-vinyl alcohol copolymer in the ethylene-vinyl alcohol copolymer modified silica aerogel was 14 wt%). The preparation method of potassium sodium silicate binder includes the following steps: potassium silicate, sodium silicate and water are mixed at 60°C and 300 rpm for 30 min, matured for 3 h, and cooled to obtain potassium sodium silicate binder (solid content 30%); the mass ratio of potassium silicate to sodium silicate is 1:1.2. The preparation method of nano-aerogel thermal insulation coating includes the following steps: The filler was pre-treated by crushing and then sieved through a 300-mesh ultrasonic vibrating screen (vibration frequency 30kHz) to obtain pre-treated filler. The potassium sodium silicate binder and the pre-treated filler were mixed to obtain a preliminary mixture. Ethylene-vinyl alcohol copolymer modified silica aerogel, polyether modified polysiloxane leveling agent, and attapulgite clay were added and mixed further. The mixture was filtered through a 250-mesh filter and degassed in a vacuum degassing machine (-0.09MPa vacuum, 80rpm) for 15 minutes to obtain a nano aerogel thermal insulation coating.

[0031] Example 3 Nano-aerogel thermal insulation coating comprises the following components in parts by weight: 40 parts of potassium sodium silicate binder, 20 parts of ethylene-vinyl alcohol copolymer modified silica aerogel, 30 parts of filler, 2 parts of polyether modified polysiloxane leveling agent, and 3 parts of attapulgite clay; the filler is hollow glass microspheres, zirconium oxide, alumina and mullite fiber in a mass ratio of 5:1:1:1. A method for preparing ethylene-vinyl alcohol copolymer modified silica aerogel includes the following steps: The ethylene-vinyl alcohol copolymer was dissolved in a 75% (v / v) aqueous solution of isopropanol to obtain a solution. Tetraethyl orthosilicate, ethanol, and hydrochloric acid solution (0.05M) were mixed and hydrolyzed at a mass ratio of 1.2:1:0.1 to obtain a hydrolysate. Ammonia water (0.3M) (volume ratio of hydrolysate to ammonia water was 4:1) was added to the hydrolysate for catalysis. After standing for 24 hours, gel A was obtained. Gel A was aged at 28°C for 24 hours, and then subjected to solvent (isopropanol) exchange for 24 hours to obtain gel B; Gel B was immersed in a dissolving solution (70℃) for 3 days, phase separation was performed at 30℃, and solvent (isopropanol) exchange was carried out for 24 hours to obtain the modified gel. The modified gel was subjected to supercritical carbon dioxide drying and pulverized to obtain ethylene-vinyl alcohol copolymer modified silica aerogel (the content of ethylene-vinyl alcohol copolymer in the ethylene-vinyl alcohol copolymer modified silica aerogel was 13wt%). The preparation method of potassium sodium silicate binder includes the following steps: potassium silicate, sodium silicate and water are mixed at 50°C and 250 rpm for 50 min, matured for 2 h, and cooled to obtain potassium sodium silicate binder (solid content 35%); the mass ratio of potassium silicate to sodium silicate is 1:0.8. The preparation method of nano-aerogel thermal insulation coating includes the following steps: The filler was pre-treated by crushing and then sieved through a 300-mesh ultrasonic vibrating screen (vibration frequency 30kHz) to obtain pre-treated filler. The potassium sodium silicate binder and the pre-treated filler were mixed to obtain a preliminary mixture. Ethylene-vinyl alcohol copolymer modified silica aerogel, polyether modified polysiloxane leveling agent, and attapulgite clay were added and mixed further. The mixture was filtered through a 250-mesh filter and degassed in a vacuum degassing machine (-0.09MPa vacuum, 80rpm) for 15 minutes to obtain a nano aerogel thermal insulation coating.

[0032] Example 4 Nano-aerogel thermal insulation coating comprises the following components in parts by weight: 40 parts of potassium sodium silicate binder, 20 parts of ethylene-vinyl alcohol copolymer modified silica aerogel, 30 parts of filler, 2 parts of polyether modified polysiloxane leveling agent, and 3 parts of attapulgite clay; the filler is hollow glass microspheres, zirconium oxide, alumina and mullite fiber in a mass ratio of 5:1:1:1. A method for preparing ethylene-vinyl alcohol copolymer modified silica aerogel includes the following steps: The ethylene-vinyl alcohol copolymer was dissolved in a 75% (v / v) aqueous solution of isopropanol to obtain a solution. Tetraethyl orthosilicate, ethanol, and hydrochloric acid solution (0.05M) were mixed and hydrolyzed at a mass ratio of 1.2:1:0.1 to obtain a hydrolysate. Ammonia water (0.3M) (volume ratio of hydrolysate to ammonia water was 4:1) was added to the hydrolysate for catalysis. After standing for 24 hours, gel A was obtained. Gel A was aged at 28°C for 24 hours, and then subjected to solvent (isopropanol) exchange for 24 hours to obtain gel B; Gel B was first soaked in a nano-montmorillonite dispersion for 2 days, then soaked in a solution (70℃) for 3 days, phase separation was performed at 30℃, and solvent (isopropanol) exchange was carried out for 24 hours to obtain the modified gel. The modified gel was subjected to supercritical carbon dioxide drying and pulverized to obtain ethylene-vinyl alcohol copolymer modified silica aerogel (the content of ethylene-vinyl alcohol copolymer in the ethylene-vinyl alcohol copolymer modified silica aerogel is 13wt%, and the content of nano-montmorillonite is 5wt%). The preparation method of potassium sodium silicate binder includes the following steps: potassium silicate, sodium silicate and water are mixed at 50°C and 250 rpm for 50 min, matured for 2 h, and cooled to obtain potassium sodium silicate binder (solid content 35%); the mass ratio of potassium silicate to sodium silicate is 1:0.8. The preparation method of nano-aerogel thermal insulation coating includes the following steps: The filler was pre-treated by crushing and then sieved through a 300-mesh ultrasonic vibrating screen (vibration frequency 30kHz) to obtain pre-treated filler. The potassium sodium silicate binder and the pre-treated filler were mixed to obtain a preliminary mixture. Ethylene-vinyl alcohol copolymer modified silica aerogel, polyether modified polysiloxane leveling agent, and attapulgite clay were added and mixed further. The mixture was filtered through a 250-mesh filter and degassed in a vacuum degassing machine (-0.09MPa vacuum, 80rpm) for 15 minutes to obtain a nano aerogel thermal insulation coating.

[0033] Example 5 Nano-aerogel thermal insulation coating comprises the following components in parts by weight: 40 parts of potassium sodium silicate binder, 20 parts of ethylene-vinyl alcohol copolymer modified silica aerogel, 30 parts of filler, 2 parts of polyether modified polysiloxane leveling agent, and 3 parts of attapulgite clay; the filler is hollow glass microspheres, zirconium oxide, alumina and mullite fiber in a mass ratio of 5:1:1:1. A method for preparing ethylene-vinyl alcohol copolymer modified silica aerogel includes the following steps: The ethylene-vinyl alcohol copolymer was dissolved in a 75% (v / v) aqueous solution of isopropanol to obtain a solution. Tetraethyl orthosilicate, ethanol, and hydrochloric acid solution (0.05M) were mixed and hydrolyzed at a mass ratio of 1.2:1:0.1 to obtain a hydrolysate. Ammonia water (0.3M) (volume ratio of hydrolysate to ammonia water was 4:1) was added to the hydrolysate for catalysis. After standing for 24 hours, gel A was obtained. Gel A was aged at 28°C for 24 hours, and then subjected to solvent (isopropanol) exchange for 24 hours to obtain gel B; Gel B was first soaked in a nano-montmorillonite dispersion for 2 days, then soaked in a solution (70℃) for 3 days, phase separation was performed at 30℃, and solvent (isopropanol) exchange was carried out for 24 hours to obtain the modified gel. The modified gel was subjected to supercritical carbon dioxide drying and pulverized to obtain ethylene-vinyl alcohol copolymer modified silica aerogel (the content of ethylene-vinyl alcohol copolymer in the ethylene-vinyl alcohol copolymer modified silica aerogel is 13wt%, and the content of nano-montmorillonite is 8wt%). The preparation method of potassium sodium silicate binder includes the following steps: potassium silicate, sodium silicate and water are mixed at 50°C and 250 rpm for 50 min, matured for 2 h, and cooled to obtain potassium sodium silicate binder (solid content 35%); the mass ratio of potassium silicate to sodium silicate is 1:0.8. The preparation method of nano-aerogel thermal insulation coating includes the following steps: The filler was pre-treated by crushing and then sieved through a 300-mesh ultrasonic vibrating screen (vibration frequency 30kHz) to obtain pre-treated filler. The potassium sodium silicate binder and the pre-treated filler were mixed to obtain a preliminary mixture. Ethylene-vinyl alcohol copolymer modified silica aerogel, polyether modified polysiloxane leveling agent, and attapulgite clay were added and mixed further. The mixture was filtered through a 250-mesh filter and degassed in a vacuum degassing machine (-0.09MPa vacuum, 80rpm) for 15 minutes to obtain a nano aerogel thermal insulation coating.

[0034] Comparative Example 1 The only difference between this comparative example and Example 3 is that the ethylene-vinyl alcohol copolymer modified silica aerogel is replaced with silica aerogel.

[0035] Comparative Example 2 The only difference between this comparative example and Example 3 is that the ethylene-vinyl alcohol copolymer is replaced with polymethyl methacrylate.

[0036] Experimental Example 1 The thermal insulation performance of the nano-aerogel thermal insulation coatings prepared in the examples and comparative examples was tested according to the standard GB / T 10295-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Thermal Insulation Materials - Heat Flow Meter Method". The results are shown in Table 1 below.

[0037] Table 1 Test Results

[0038] Compared with Comparative Examples 1-2, the nano-aerogel thermal insulation coatings prepared in Examples 1-5 have lower thermal conductivity, indicating that the modification of silica aerogel with ethylene-vinyl alcohol copolymer and the addition of nano-montmorillonite improve the thermal insulation performance of the aerogel coating.

[0039] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A nanoaerogel thermal barrier coating, characterized in that, The components include the following parts by weight: The composition includes 35-50 parts of silicate binder, 10-30 parts of polymer-modified silica aerogel, 20-40 parts of filler, and 1.5-8 parts of additives; the polymer includes ethylene-vinyl alcohol copolymer.

2. The nano-aerogel thermal barrier coating of claim 1, wherein, The polymer content in the polymer-modified silica aerogel is 12% to 14%.

3. The nano-aerogel thermal barrier coating of claim 1, wherein, The packing material includes at least one of spherical packing and fibrous packing; The spherical filler includes at least one of hollow glass microspheres, zirconium oxide, and alumina; The fibrous filler includes at least one of mullite fiber and aluminosilicate fiber; Preferably, the spherical filler comprises hollow glass microspheres, zirconium oxide, and alumina; the fibrous filler comprises mullite fibers.

4. The nano-aerogel heat-insulating coating according to claim 1, characterized in that, The additives include at least one of leveling agents, suspending agents, and defoamers; Preferably, the additive comprises the following components in parts by weight: 0.5 to 3 parts of leveling agent and 1 to 5 parts of suspending agent.

5. The nano-aerogel thermal insulation coating according to claim 1, characterized in that, The silicate binder includes a potassium sodium silicate binder with a solid content of 25% to 35%.

6. The nano-aerogel thermal insulation coating according to claim 5, characterized in that, The preparation method of the potassium sodium silicate binder includes the following steps: mixing potassium silicate, sodium silicate and water, aging, and cooling to obtain the potassium sodium silicate binder.

7. The nano-aerogel thermal insulation coating according to claim 2, characterized in that, The preparation method of the polymer-modified silica aerogel includes the following steps: The polymer is dissolved to obtain a solution; The silicon source was hydrolyzed, ammonia was added for catalysis, and the mixture was allowed to stand to obtain gel A; After the gel A ages, solvent exchange is performed to obtain gel B; The gel B was immersed in the solution, the phases were separated, and solvent exchange was performed to obtain the modified gel. The modified gel was dried and pulverized to obtain polymer-modified silica aerogel.

8. The nano-aerogel thermal insulation coating according to claim 7, characterized in that, The hydrolysis step specifically involves mixing a silicon source with an ethanol and hydrochloric acid solution to obtain a hydrolysate. The mass ratio of the silicon source, ethanol, and hydrochloric acid solution is 1.1~1.3:1:0.1; The aging time is 24 hours, and the temperature is 25~30℃; The soaking temperature is 65~70℃, and the soaking time is 2.5~3.5 days.

9. The nano-aerogel heat-insulating coating according to claim 1, characterized in that, The polymer-modified silica aerogel also includes nano-montmorillonite, with a content of 5% to 8%.

10. A method for preparing a nano-aerogel thermal insulation coating, used to prepare the nano-aerogel thermal insulation coating according to any one of claims 1 to 9, characterized in that, Includes the following steps: The silicate binder and filler are mixed, and then polymer-modified silica aerogel and additives are added and mixed further to obtain a nano-aerogel heat insulation coating.

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