Nano thermal insulation coating and preparation method thereof

Abstract

The invention discloses a nano thermal insulation coating and a preparation method thereof, and belongs to the technical field of nano coatings. The nano heat insulation coating comprises the following components in parts by weight: 15-30 parts of silicon dioxide aerogel powder, 20-40 parts of high-performance resin, 5-10 parts of an inorganic binder, 2-5 parts of an auxiliary agent and 20-35 parts of deionized water, the pore diameter of the silicon dioxide aerogel powder is smaller than or equal to 70 nm, and the heat conductivity coefficient is smaller than or equal to 0.013 W / mK; the high-performance resin is water-based environment-friendly resin, the auxiliaries comprise a dispersing agent, a flame retardant and a defoaming agent, and the mass ratio of all the components is 2: 2: 1. The thermal conductivity of the finished product is as low as less than or equal to 0.045 W / mK and the thermal insulation efficiency is far higher than that of the traditional coating by virtue of the accurate parameters (the pore diameter is less than or equal to 70nm, the thermal conductivity is less than or equal to 0.013 W / mK and the specific surface area is 300-800m / g) of the silicon dioxide aerogel powder and a uniform dispersion process. By combining the compounding design of the inorganic binder and the high-performance resin, the temperature resistance limit covers 250-800 DEG C, the normal-temperature heat insulation requirement of a building wall body can be met, and the heat insulation material can also adapt to extreme scenes such as industrial high-temperature pipelines and kilns.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nano-coating, more particularly to a nano-thermal insulation coating and a preparation method thereof. BACKGROUND

[0002] With the promotion of energy saving and emission reduction and the upgrading of the demand for thermal insulation in the fields of industrial production and construction, as a high-efficiency energy-saving material, the application scenarios of thermal insulation coating have been expanded from traditional building walls to industrial high-temperature equipment (such as pipelines, reaction kettles, kilns), aerospace and other fields. Traditional thermal insulation materials (such as polyurethane foam, rock wool, glass wool) have defects such as high density, complicated construction, low temperature limit (usually <200℃), poor environmental protection, etc., and are difficult to meet the comprehensive needs of modern industry for "lightweight, high-efficiency thermal insulation, green environmental protection, and extreme temperature resistance".

[0003] To solve the above problems, nano-thermal insulation coating emerges as the times require, and among them, the coating with silica aerogel as the core functional filler has become a research hotspot in the industry because of its extremely low thermal conductivity. Silica aerogel, with its nanoscale pore structure (pore size usually <100nm), can effectively block heat conduction, heat convection and heat radiation, and its thermal conductivity is even lower than that of static air, and it is recognized as one of the most excellent thermal insulation materials to date. However, the nano-aerogel thermal insulation coating in the prior art still has many technical bottlenecks to be solved: Insufficient performance regulation of core filler: the existing technology mostly only uses silica aerogel as filler without precise limitation on its key parameters (such as pore size, thermal conductivity). When the pore size of aerogel exceeds 70nm, the internal air is prone to flow, resulting in the failure of "zero convection" thermal insulation effect and a significant decrease in thermal insulation performance; at the same time, the threshold value of the thermal conductivity of aerogel itself is not clear, and some products are difficult to achieve high-efficiency thermal insulation due to the use of low-quality aerogel (thermal conductivity >0.015W / m・K).

[0004] Unreasonable component matching, performance conflict prominent: on the one hand, the additive system lacks scientific proportioning, and the dispersant, flame retardant and defoaming agent are randomly added, which may cause problems such as "excessive dispersant leading to reduced flame retardant efficiency" and "insufficient defoaming agent causing shrinkage of the coating", and it is difficult to balance the dispersing uniformity, flame retardancy and coating flatness; on the other hand, some coatings use solvent-based resins, which can improve the mechanical properties but exceed the VOC emission standard, not meeting the requirements of environmental protection policies; and the existing water-based aerogel coatings generally have low tensile strength (<1MPa) and narrow temperature limit (<250℃), which are difficult to adapt to industrial high-temperature scenarios.

[0005] Therefore, developing a kind of nano thermal insulation coating by accurately regulating aerogel parameters, optimizing component ratio, improving preparation process, realizing "high efficiency heat insulation, environmental protection, non-toxic, excellent mechanical property, wide temperature resistance range, convenient construction" becomes the key to solve the defects of prior art and promote the large-scale application of thermal insulation coating in many fields.In view of this, we propose a kind of nano thermal insulation coating and its preparation method. SUMMARY

[0006] The present application aims to provide a kind of nano thermal insulation coating and its preparation method to solve the problems raised in the above background.

[0007] To achieve the above object, the present application provides the following technical scheme: A kind of nano thermal insulation coating, its component ingredients include the following components with weight ratio: 15-30 parts of silica aerogel powder, 20-40 parts of high-performance resin, 5-10 parts of inorganic binder, 2-5 parts of auxiliary agent, 20-35 parts of deionized water; The pore size of silica aerogel powder is ≤70nm, and the thermal conductivity is ≤0.013W / m・K; The high-performance resin is water-based environmental protection resin, the auxiliary agent includes dispersant, flame retardant and defoaming agent, and the mass ratio of each component is 2:2:1.

[0008] Preferably, the inorganic binder is one of silica sol or aluminum sol or a combination of both; The dispersant is polycarboxylate dispersant, the flame retardant is aluminum hydroxide or magnesium hydroxide, and the defoaming agent is silicone defoaming agent.

[0009] Preferably, the high-performance resin is one or a combination of water-based acrylic resin, water-based polyurethane resin or water-based epoxy resin, and the resin solid content is 30%-50%.

[0010] Preferably, the purity of silica aerogel powder is ≥99%, and the solid content of inorganic binder is 20%-30%.

[0011] Preferably, the specific surface area of silica aerogel powder is 300-800m² / g, and the loose bulk density is 0.05-0.15g / cm³;The hydroxyl value of high-performance resin is 50-150mgKOH / g;The particle size of inorganic binder is 10-50nm;The molecular weight of dispersant is 5000-20000.

[0012] A kind of nano thermal insulation coating preparation method, comprising the following steps: S1, raw material pretreatment: dry silica aerogel powder at 100-120℃ for 2-3h to remove moisture;Pre-stirring is carried out on high-performance resin, the stirring speed is 300-500r / min, and the stirring time is 15-20min, to ensure that the resin is uniformly dispersed; S2, mixing and dispersing: deionized water is added to the pretreated high-performance resin, and after stirring uniformly, a dispersing agent and a defoaming agent are sequentially added, and stirring is performed at a rotation speed of 800-1000 r / min for 30-40 min; then, silica aerogel powder and a flame retardant are slowly added, the temperature is increased to 40-50 DEG C, and a high-speed disperser is used to disperse at a rotation speed of 1500-2000 r / min for 60-90 min, to obtain a mixed slurry; S3, grinding and refining: the mixed slurry is sent into a grinding machine for grinding, and the particle size of the solid particles in the slurry after grinding is controlled to be less than or equal to 5 microns; S4, adjusting performance: an inorganic binder is added to the slurry after grinding, and stirring is performed at a rotation speed of 600-800 r / min for 20-30 min, to adjust the viscosity of the slurry to 50-100 mPa s, to obtain a nano thermal insulation coating preliminary product; S5, filtering and packaging: the nano thermal insulation coating preliminary product is filtered through a 200-300 mesh filter screen to remove impurities and particles that are not uniformly dispersed, and after filtering, the product is sealed and packaged, to obtain a finished product.

[0013] Preferably, in step S2, the silica aerogel powder is added at a speed of 5-10 g / min to avoid agglomeration of the powder.

[0014] Preferably, in step S4, the viscosity is adjusted by using deionized water or a water-based thickening agent for fine adjustment, to ensure that the coating workability meets the requirements of batch scraping or spraying.

[0015] Preferably, in step S5, the finished product of the coating after filtering is first placed in an environment with a temperature of 25-30 DEG C and a relative humidity of 40-60% for 12-24 hours before being sealed and packaged, to eliminate internal stress of the slurry and improve the flatness of the coating after construction.

[0016] Preferably, in step S3, the grinding machine is a sand mill, and the temperature of the slurry during grinding is controlled to be less than or equal to 60 DEG C, and the grinding time is 30-60 min, to ensure that the solid particles are uniformly refined to the target particle size.

[0017] Compared with the prior art, the present application has the following advantages: (1) The present application relies on the precise parameters (pore size ≤70 nm, thermal conductivity ≤0.013 W / m K, specific surface area 300-800 m² / g) of the silica aerogel powder and the uniform dispersion process, and the finished product has a thermal conductivity of ≤0.045 W / m K, which is much higher than that of traditional coatings; combined with the compounding design of inorganic binders and high-performance resins, the temperature resistance limit covers 250-800 DEG C, which can not only meet the normal temperature insulation requirements of building walls, but also adapt to extreme scenarios such as industrial high-temperature pipelines and kilns, to realize the scene adaptation advantage of "one material for multiple purposes".

[0018] (2) The water-based environmental protection resin and water-based system are adopted, the VOC release meets the national standard, there is no formaldehyde, heavy metal and other harmful substances, there is no pollution in the construction and use process, and the policy guidance of energy saving, emission reduction and environmental protection is met; through the optimization of chemical bonding between components (such as matching the resin hydroxyl group and the particle size of the binder), the paint has strong adhesion, the tensile strength is greater than 1 MPa, the water resistance and salt spray corrosion resistance are good, the service life is prolonged by more than 30% than that of conventional products, and the long-term test of indoor and outdoor and industrial harsh environment can be tolerated.

[0019] (3) Through the process design of precise viscosity adjustment (50-100 mPa・s), sand mill grinding (particle size ≤5 μm) and stress elimination by standing, the paint can be flexibly adapted to various construction methods such as batch scraping and spraying, and can be adapted to flat building walls and special-shaped industrial equipment (valves and flanges); the coated surface is smooth and flat, and there is no shrinkage hole, sagging and other defects, and no additional leveling is needed, which greatly improves the construction efficiency and the forming appearance quality. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments.

[0021] Embodiment: A kind of nano thermal insulation coating, including its component ingredients with weight ratio including the following components: silica aerogel powder 15-30 parts, high-performance resin 20-40 parts, inorganic binder 5-10 parts, auxiliary agent 2-5 parts, deionized water 20-35 parts; The pore size of the silica aerogel powder is ≤70 nm, and the thermal conductivity is ≤0.013 W / m・K; the purity of the silica aerogel powder is ≥99%, and the solid content of the inorganic binder is 20%-30%; the specific surface area of the silica aerogel powder is 300-800 m² / g, and the loose bulk density is 0.05-0.15 g / cm³.

[0022] The high-performance resin is a water-based environmental protection resin, the auxiliary agent includes a dispersing agent, a flame retardant and a defoaming agent, and the mass ratio of each component is 2:2:1; the high-performance resin is one or more of a water-based acrylic resin, a water-based polyurethane resin or a water-based epoxy resin, and the resin solid content is 30%-50%; the hydroxyl value of the high-performance resin is 50-150 mgKOH / g.

[0023] In this application, the inorganic binder is one or a combination of silica sol and aluminum sol; the dispersing agent is a polycarboxylate dispersing agent, the flame retardant is aluminum hydroxide or magnesium hydroxide, and the defoaming agent is an organic silicon defoaming agent. The particle size of the inorganic binder is 10-50 nm; the molecular weight of the dispersing agent is 5000-20000.

[0024] The application takes advantage of the "zero convection" and "infinite path" heat insulation mechanism of silica aerogel powder (pore size ≤70 nm, thermal conductivity ≤0.013 W / m·K, specific surface area 300-800 m² / g), combined with uniform dispersion process design, the finished product thermal conductivity ≤0.045 W / m·K, far superior to traditional water-based thermal insulation coatings (conventional 0.05-0.06 W / m·K), a 3mm thick coating can achieve a temperature difference barrier of more than 50℃. Through the compounding and optimization of inorganic binders (silica sol / aluminum sol) and high-performance resins, the coating temperature limit covers 250-800℃, which can adapt to the thermal insulation needs of different temperature scenes such as building walls, industrial high-temperature pipelines, reaction kettles, kilns, etc. It not only meets the normal temperature insulation, but also can withstand the long-term test of industrial high-temperature environment. Using water-based environmentally friendly resin (solid content 30%-50%) and water-based system, it does not contain formaldehyde, heavy metals and other toxic and harmful substances, and the VOC emission meets the national standards such as GB18582-2020 "Limit of Harmful Substances in Architectural Wall Coatings", etc. There is no irritating odor during construction and use, which is friendly to human health and environment. The flame-retardant protection effect is remarkable: the flame retardant (aluminum hydroxide / magnesium hydroxide) in the additive synergizes with other components, and the coating combustion grade reaches A level (non-combustible), does not produce toxic smoke when on fire, can effectively prevent the spread of fire, and improves the fire safety performance of the coated substrate (such as building walls, industrial equipment).

[0025] The inorganic binder (particle size 10-50 nm) forms a strong chemical bond with the hydroxyl group (50-150 mgKOH / g) of the high-performance resin, the adhesion level of the coating to the cement substrate, metal surface and other substrates is not less than 1 level (circle method), and the tensile strength is >1MPa, which can avoid problems such as cracking, drumming and falling off during long-term use. Strong weather resistance and corrosion resistance: after 72h of immersion in (23±2)℃ distilled water, the coating has no drumming and discoloration; after 500h of continuous spraying with 5% NaCl aqueous solution, there is no rust and pitting, which can resist complex environmental erosion such as humidity and salt spray, and is suitable for long-term use in indoor and outdoor, industrial harsh environment and other scenes, with a service life extended by more than 30% compared with conventional thermal insulation coatings. Through precise viscosity adjustment (50-100 mPa·s), the coating can adapt to various construction methods such as batch scraping and spraying, and can adapt to the construction needs of different substrate structures such as building walls and special-shaped industrial equipment (valves, flanges), with simple operation.

[0026] A preparation method of a nano thermal insulation coating, comprising the following steps: S1, raw material pretreatment: dry the silica aerogel powder at 100-120℃ for 2-3h to remove water; pre-stir the high-performance resin at a speed of 300-500r / min for 15-20min to ensure uniform dispersion of the resin.

[0027] S2, mixing and dispersing: add deionized water to the pretreated high-performance resin, stir uniformly, then add dispersant, defoaming agent, stir at a speed of 800-1000 r / min for 30-40 min; then slowly add silica aerogel powder and flame retardant, heat to 40-50℃, use a high-speed disperser to disperse at a speed of 1500-2000 r / min for 60-90 min, to obtain a mixed slurry; the addition speed of silica aerogel powder is 5-10 g / min to avoid powder agglomeration.

[0028] S3, grinding and refining: the mixed slurry is sent to a grinding machine for grinding, the particle size of the solid particles in the slurry after grinding is controlled to be ≤5 μm; the grinding machine is a sand mill, the slurry temperature during grinding is controlled to be ≤60℃, the grinding time is 30-60 min, to ensure that the solid particles are uniformly refined to the target particle size. During the preparation process, the sand mill is used for grinding (particle size ≤5 μm), and the internal stress is eliminated by standing (standing for 12-24 h in an environment of 25-30℃ and humidity of 40%-60%), the finished coating has a smooth surface after coating, without defects such as shrinkage hole and sagging, and no additional leveling treatment is needed, which improves the construction efficiency while ensuring the appearance quality.

[0029] S4, adjusting performance: add inorganic binder to the ground slurry, stir at a speed of 600-800 r / min for 20-30 min, adjust the viscosity of the slurry to 50-100 mPa・s, to obtain the nano thermal insulation coating primary product; the viscosity adjustment is fine-tuned by deionized water or water-based thickening agent, to ensure that the coating workability meets the requirements of batch scraping or spraying.

[0030] S5, filtering and packaging: the nano thermal insulation coating primary product is filtered through a 200-300 mesh filter screen to remove impurities and particles that are not uniformly dispersed, and then sealed and packaged after filtration, to obtain the finished product. Before sealing and packaging, the filtered coating product is first placed in an environment of 25-30℃ and relative humidity of 40%-60% for 12-24 h to eliminate the internal stress of the slurry and improve the flatness of the coating after construction.

[0031] Example 1 (intermediate value formula) Silica aerogel powder 22 parts, with a pore size of 50 nm, a thermal conductivity of 0.010 W / m・K, a purity of 99.5%, a specific surface area of 500 m² / g, and a bulk density of 0.10 g / cm³; high-performance resin 30 parts, which is a water-based acrylic resin with a solid content of 40% and a hydroxyl value of 100 mgKOH / g; inorganic binder 8 parts, which is a silica sol with a solid content of 25% and a particle size of 30 nm; additives 3.5 parts, including dispersant: flame retardant: defoaming agent = 2:2:1, the dispersant is a polycarboxylate with a molecular weight of 10000, the flame retardant is aluminum hydroxide, and the defoaming agent is an organic silicon; deionized water 26.5 parts.

[0032] Example 2 (low aerogel dosage) Silica aerogel powder 15 parts, pore size 60 nm, thermal conductivity 0.012 W / m-K, purity 99%, specific surface area 300 m2 / g, loose bulk density 0.05 g / cm3; high-performance resin 20 parts, water-based polyurethane resin, solid content 30%, hydroxyl value 50 mgKOH / g; inorganic binder 5 parts, aluminum sol, solid content 20%, particle size 10 nm; additives 2 parts, wherein dispersant: flame retardant: defoamer = 2:2:1, dispersant is polycarboxylate, molecular weight 5000, flame retardant is magnesium hydroxide, defoamer is silicone; deionized water 38 parts.

[0033] Example 3 (high aerogel dosage) Silica aerogel powder 30 parts, pore size 40 nm, thermal conductivity 0.009 W / m-K, purity 99.8%, specific surface area 800 m2 / g, loose bulk density 0.15 g / cm3; high-performance resin 40 parts, water-based epoxy resin, solid content 50%, hydroxyl value 150 mgKOH / g; inorganic binder 10 parts, silica sol, solid content 30%, particle size 50 nm; additives 5 parts, wherein dispersant: flame retardant: defoamer = 2:2:1, dispersant is polycarboxylate, molecular weight 20000, flame retardant is aluminum hydroxide, defoamer is silicone; deionized water 15 parts.

[0034] Example 4 (resin compounding) Silica aerogel powder 25 parts, pore size 55 nm, thermal conductivity 0.011 W / m-K, purity 99.2%, specific surface area 600 m2 / g, loose bulk density 0.08 g / cm3; high-performance resin 35 parts, compounded from water-based acrylic resin and water-based polyurethane resin at a ratio of 1:1, solid content 45%, hydroxyl value 80 mgKOH / g; inorganic binder 7 parts, compounded from silica sol and aluminum sol at a ratio of 3:2, solid content 22%, particle size 25 nm; additives 4 parts, wherein dispersant: flame retardant: defoamer = 2:2:1, dispersant is polycarboxylate, molecular weight 15000, flame retardant is magnesium hydroxide, defoamer is silicone; deionized water 29 parts.

[0035] Example 5 (binder compounding) Silica aerogel powder 20 parts, pore size 45 nm, thermal conductivity 0.010 W / m・K, purity 99.3%, specific surface area 450 m² / g, loose bulk density 0.12 g / cm³; high-performance resin 28 parts, compounded from water-based epoxy resin and water-based acrylic resin at a ratio of 2:1, solid content 38%, hydroxyl value 120 mgKOH / g; inorganic binder 9 parts, compounded from silica sol and alumina sol at a ratio of 1:1, solid content 28%, particle size 40 nm; additives 3 parts, wherein dispersant: flame retardant: defoamer = 2:2:1, dispersant is polycarboxylate with a molecular weight of 8000, flame retardant is aluminum hydroxide, and defoamer is silicone; deionized water 30 parts.

[0036] Preparation steps of examples 1-5 S1, raw material pretreatment The silica aerogel powder in each example was dried in a 110°C oven for 2.5 hours to remove moisture; the high-performance resin was pre-stirred at 400 r / min for 18 minutes to ensure uniform dispersion of the resin.

[0037] S2, mixing and dispersion The corresponding amount of deionized water was added to the pretreated high-performance resin, and after stirring evenly, the dispersant, defoamer were added in turn, and stirred at 900 r / min for 35 min; then the silica aerogel powder and flame retardant were slowly added at a speed of 5-10 g / min, and the temperature was raised to 45°C, and the high-speed disperser was used to disperse at 1800 r / min for 75 min to obtain the mixed slurry.

[0038] S3, grinding and refining The mixed slurry was sent to the sand mill for grinding, and the slurry temperature was controlled ≤60°C during the grinding process, and the grinding time was 45 min, to ensure that the particle size of the solid particles in the slurry after grinding was ≤5 μm.

[0039] S4, adjusting performance The inorganic binder was added to the ground slurry, and stirred at 700 r / min for 25 min, and the slurry viscosity was adjusted to 75 mPa・s with deionized water, to obtain the nano thermal insulation coating primary product.

[0040] S5, filtration and packaging The nano thermal insulation coating primary product was filtered through a 250 mesh filter screen to remove impurities and particles that were not uniformly dispersed; after filtration, the coating was placed in an environment of 28°C and 50% relative humidity for 18 hours to eliminate internal stress of the slurry, and then sealed and packaged to obtain the finished product.

[0041] Performance test results of examples 1-5 The finished products of each embodiment were detected according to the following standards, and the results are shown in Table 1 below (the detection data is only used to verify the feasibility of the technical scheme, and does not constitute a functional limitation): Table 1 Performance detection results of examples 1-5 The examples 1-5 of the present application prove that the technical scheme defined in the present application has wide implementability. The preparation process strictly follows the process parameters of the present application (drying temperature 100-120℃, stirring speed 300-2000r / min, grinding particle size ≤5μm, etc.), the steps are clear and the parameters are clear, and the target product can be prepared repeatedly according to the examples by those skilled in the art. The detection results of each example meet the limitations of the component parameters of the technical scheme, verifying the stability and reliability of the technical scheme of the present application.

[0042] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only preferred examples of the present application and do not limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A nano-thermal insulating coating, characterized in that, Its composition includes the following components in parts by weight: 15-30 parts of silica aerogel powder, 20-40 parts of high-performance resin, 5-10 parts of inorganic binder, 2-5 parts of additives, and 20-35 parts of deionized water. The silica aerogel powder has a pore size ≤70nm and a thermal conductivity ≤0.013W / m・K; The high-performance resin is a water-based environmentally friendly resin, and the additives include dispersants, flame retardants, and defoamers, with a mass ratio of 2:2:1 for each component.

2. The nano-thermal insulating coating according to claim 1, characterized in that: The inorganic binder is one or a combination of two of silica sol and alumina sol. The dispersant is a polycarboxylate dispersant, the flame retardant is aluminum hydroxide or magnesium hydroxide, and the defoamer is an organosilicon defoamer.

3. The nano-thermal insulating coating according to claim 1, characterized in that: The high-performance resin is one or more of waterborne acrylic resin, waterborne polyurethane resin or waterborne epoxy resin, and the resin solid content is 30%-50%.

4. The nano-thermal insulating coating according to claim 1, characterized in that: The purity of the silica aerogel powder is ≥99%, and the solid content of the inorganic binder is 20%-30%.

5. The nano-thermal insulating coating according to claim 1, characterized in that: The silica aerogel powder has a specific surface area of ​​300-800 m² / g and a loose density of 0.05-0.15 g / cm³; the high-performance resin has a hydroxyl value of 50-150 mg KOH / g; the inorganic binder has a particle size of 10-50 nm; and the dispersant has a molecular weight of 5000-20000.

6. A method for preparing a nano-thermal insulating coating as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Raw material pretreatment: Dry the silica aerogel powder at 100-120℃ for 2-3 hours to remove moisture; pre-stir the high-performance resin at a speed of 300-500r / min for 15-20min to ensure uniform dispersion of the resin. S2. Mixing and Dispersion: Add deionized water to the pretreated high-performance resin, stir evenly, then add dispersant and defoamer in sequence, and stir at 800-1000 r / min for 30-40 min; then slowly add silica aerogel powder and flame retardant, heat to 40-50℃, and disperse using a high-speed disperser at 1500-2000 r / min for 60-90 min to obtain a mixed slurry; S3. Grinding and refining: The mixed slurry is fed into a grinding mill for grinding, and the particle size of solid particles in the slurry after grinding is controlled to be ≤5μm; S4. Adjusting performance: Add inorganic binder to the ground slurry, stir at 600-800 r / min for 20-30 min, adjust the slurry viscosity to 50-100 mPa·s, and obtain the initial nano heat insulation coating; S5. Filtration and Packaging: The initial nano-thermal insulation coating is filtered through a 200-300 mesh filter to remove impurities and unevenly dispersed particles. After filtration, it is sealed and packaged to obtain the finished product.

7. The method for preparing a nano-thermal insulating coating according to claim 6, characterized in that: In step S2, the silica aerogel powder is added at a rate of 5-10 g / min to avoid powder agglomeration.

8. The method for preparing a nano-thermal insulating coating according to claim 6, characterized in that: In step S4, viscosity is finely adjusted using deionized water or a water-based thickener to ensure that the coating's workability meets the requirements for troweling or spraying.

9. The method for preparing a nano-thermal insulating coating according to claim 6, characterized in that: Before sealing and packaging the filtered coating product from step S5, let it stand for 12-24 hours at 25-30℃ and 40%-60% relative humidity to eliminate internal stress in the slurry and improve the smoothness of the coating after application.

10. The method for preparing a nano-thermal insulating coating according to claim 6, characterized in that: The grinding mill mentioned in step S3 is a sand mill. During the grinding process, the slurry temperature is controlled to be ≤60℃ and the grinding time is 30-60min to ensure that the solid particles are uniformly refined to the target particle size.

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