A kind of reflective heat-insulating aerogel coating and preparation method thereof

Abstract

The present invention discloses a reflective, thermally insulating aerogel coating and its preparation method, belonging to the technical field of energy-saving functional coatings for buildings. The reflective, thermally insulating aerogel coating comprises the following components by weight: 40-60 parts of a film-forming emulsion, 5-15 parts of modified silica aerogel, 5-10 parts of graded hollow glass microspheres, 4-8 parts of a functional filler, 1-3 parts of an additive, and 20-40 parts of deionized water. The reflective, thermally insulating aerogel coating exhibits excellent thermal insulation and energy-saving properties, and can be used for energy conservation and carbon reduction in the construction industry. It also has significant potential for energy conservation and carbon reduction in climate zones where cooling is a primary requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of building energy-saving functional coatings, and in particular to a reflective heat-insulating aerogel coating and a preparation method thereof. Background Art

[0002] In the summer, under the continuous exposure to sunlight, the temperature of the building roof can reach 40-50℃, and the temperature of the metal surface can reach 80-90℃. The accumulation and dispersion of energy has brought inconvenience to people's lives, and the use of cooling equipment has caused serious energy consumption. Therefore, it is of great significance to conduct in-depth research on the thermal insulation measures of buildings.

[0003] Reflective thermal insulation coatings, also known as solar heat reflective coatings, primarily reflect the heat-generating portion of sunlight based on the energy distribution of the solar spectrum. All substances have the ability to absorb or emit sunlight of certain wavelengths. The solar spectrum energy distribution curve shows that the solar radiation spectrum can be divided into three wavelengths: the near-infrared region (780-2500nm), the visible light region (380-780nm), and the ultraviolet region (200-380nm). The near-infrared and visible light regions account for 95% of solar radiation energy. Within this wavelength range, the higher the reflectivity, the better the coating's thermal insulation effect. Therefore, by selecting the appropriate resin, metallic pigment, filler, and production process, a coating with high solar heat reflectivity can be produced to achieve the desired thermal insulation effect.

[0004] The application principle of reflective thermal insulation coatings is mainly to add high-reflectivity thermal insulation fillers to the coatings. The high-reflectivity thermal insulation fillers commonly used in existing reports mainly include hollow glass beads, silicon carbide, titanium oxide, zinc oxide, zirconium oxide, kaolin, ceramic powder, etc. By adding these high-emissivity thermal insulation fillers, the propagation of infrared rays of different wavelengths is hindered and efficiently reflected into the atmosphere, so that the prepared coatings have better thermal insulation and cooling properties.

[0005] SiO2 aerogel has a thermal conductivity of only 0.013W / (m·K), and a porosity of 80% to 99.8% in its spatial network structure. It is non-toxic, harmless, and environmentally friendly, making it the most outstanding solid insulation material currently available. It has promising application prospects in thermal insulation coatings. There have been reports of SiO2 aerogel being used in reflective thermal insulation coatings. However, SiO2 aerogels tend to aggregate in coatings due to the nano-effect, reducing the porosity and thermal insulation performance. Furthermore, SiO2 aerogels absorb moisture, and when exposed to water, their skeleton structures tend to expand and rupture, which can also reduce the coating's weather resistance.

[0006] However, since reflective thermal insulation coatings are mostly applied as topcoats on building exteriors, long-term use can lead to uneven paint films due to erosion from external factors, which in turn affects the coating's reflective and thermal insulation properties. Therefore, reflective thermal insulation coatings containing SiO2 aerogels must maintain their reflective and thermal insulation properties while also optimizing their weather resistance, acid and alkali resistance, and stain resistance. Summary of the Invention

[0007] In view of the problems existing in the above-mentioned prior art, the object of the present invention is to provide a reflective thermal insulation aerogel coating and a preparation method thereof.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] In a first aspect of the present invention, a reflective thermal insulation aerogel coating is provided, comprising the following components in parts by weight:

[0010] 40-60 parts of film-forming emulsion, 5-15 parts of modified silica aerogel, 5-10 parts of graded hollow glass microspheres, 4-8 parts of functional filler, 1-3 parts of additives, and 20-40 parts of deionized water.

[0011] Preferably, the film-forming emulsion is composed of water-based epoxy resin, silicone acrylic emulsion and tert-fluoro emulsion in a weight ratio of 5:1:1.

[0012] The film-forming emulsion of the invention is based on water-based epoxy resin and is compounded with silicone acrylic emulsion and tert-fluoro emulsion, thereby significantly improving the anti-fouling performance of the coating.

[0013] Preferably, the modified silica aerogel is prepared by the following method:

[0014] Mix ethyl orthosilicate, ethanol, and deionized water in a molar ratio of 1:8:4, adjust the pH to 2-4 with dilute hydrochloric acid, and hydrolyze for 1-3 hours; then adjust the pH to 6-7, stir evenly, seal, and let stand until a gel is formed; age the gel, and then perform solvent replacement to obtain a wet gel;

[0015] The wet gel is placed in a trimethylchlorosilane / n-hexanol mixed solution for a first modification and dried to obtain a hydrophobic silica aerogel;

[0016] The hydrophobic silica aerogel is placed in an alkylbenzenesulfonic acid / glycerol mixed solution for secondary modification and drying to prepare the modified silica aerogel.

[0017] The modification treatment method of the present invention can improve the dispersion uniformity of the silica aerogel in the coating, thereby improving the reflective heat insulation performance of the coating.

[0018] Preferably, the graded hollow glass microspheres are composed of hollow glass microspheres HL25 and hollow glass microspheres HM10 in a weight ratio of 5:1.

[0019] The average particle size of hollow glass microspheres HL25 is 65μm, and the D50 of hollow glass microspheres HM10 is 5μm. Both types of hollow glass microspheres can provide strong and stable support and thermal insulation performance. Moreover, compared with reflective thermal insulation coatings prepared with hollow glass microspheres of a single particle size, there are a large number of gaps in the cured coating, which is not conducive to heat blocking. However, compounding hollow glass microspheres HL25 and hollow glass microspheres HM10 can effectively improve the reflective thermal insulation performance of the coating.

[0020] Preferably, the functional filler is selected from one or more of titanium dioxide, zinc oxide, zirconium oxide, talc, magnesium hydroxide whiskers and potassium titanate whiskers.

[0021] More preferably, the functional filler is composed of titanium dioxide, zirconium oxide and potassium titanate whiskers in a weight ratio of 1:1:1.

[0022] Functional fillers are mainly used to reflect solar radiation in the visible and near-infrared bands for heat insulation. The refractive ratio of the functional filler to the resin in the film-forming emulsion will affect the reflectivity of the prepared coating. After experimental optimization, titanium dioxide, zinc oxide and potassium titanate whiskers are mixed in a weight ratio of 1:1:1 as a functional filler, which has the best reflection effect on solar radiation.

[0023] Preferably, the auxiliary agent is selected from one or more of a dispersant, a wetting agent, a defoaming agent and a thickener.

[0024] More preferably, the auxiliary agent is composed of a dispersant, a wetting agent, a defoamer and a thickener in a weight ratio of 1:1:1:1; wherein:

[0025] The dispersant is selected from ZY-9401 aqueous dispersant or ZY-9002 water-oil universal dispersant;

[0026] The wetting agent is selected from ZY-2648 organosilicon wetting agent or ZY-2455 organosilicon wetting agent;

[0027] The thickener is selected from ZY-5020 polyurethane associative thickener or ZY-608 acrylic thickener;

[0028] The defoamer is selected from ZY-6310 organic silicon defoamer for water-based coatings or ZY-1024 silicone polyether defoamer (similar to BYK024).

[0029] The dispersant in the additive can improve the dispersion effect of modified silica aerogel, graded hollow glass microspheres and functional fillers in the coating, thereby affecting the reflective and thermal insulation properties of the coating; the wetting agent can not only reduce the surface energy of the modified silica aerogel, making the aerogel particles more easily combined with the emulsion, but also assist in the dispersion of the aerogel, graded hollow glass microspheres and functional fillers.

[0030] A second aspect of the present invention provides a method for preparing the above-mentioned reflective thermal insulation aerogel coating, comprising the following steps:

[0031] (1) Mixing deionized water and the additives at a low speed for 10-20 minutes, then adding the modified silica aerogel, graded hollow glass microspheres and functional fillers, and stirring and dispersing at a high speed for 20-40 minutes to obtain a mixed slurry;

[0032] (2) Adding the film-forming emulsion to the mixed slurry and stirring at a low speed for 20-40 minutes to prepare the reflective heat-insulating aerogel coating.

[0033] Preferably, in step (1), the rotation speed of the low-speed stirring is 100 r / min; the rotation speed of the high-speed stirring is 1000 r / min.

[0034] A third aspect of the present invention provides the use of the reflective thermal insulation aerogel coating in thermal insulation and cooling of building exterior surfaces, finished oil tanks, or oil pipelines.

[0035] Beneficial effects of the present invention:

[0036] (1) The present invention modifies the silica aerogel so that its surface has a certain hydrophilicity, thereby improving its dispersion performance in the coating.

[0037] (2) The present invention uses a water-based epoxy resin, a silicone acrylic emulsion and a tert-fluoro emulsion as a film-forming emulsion, thereby improving the anti-fouling performance of the coating; moreover, the Si-O chains in the silicone acrylic emulsion, the tert-fluorocarbon macromolecules in the tert-fluoro emulsion, the modified silica aerogel and the titanium, zirconium and other components in the functional filler are cross-linked together to form a three-dimensional structure, which prevents air flow and heat conduction, thereby significantly improving the structural properties of the coating.

[0038] (3) The reflective thermal insulation aerogel coating of the present invention has good thermal insulation performance and energy-saving effect, as well as excellent weather resistance, acid and alkali resistance and stain resistance. It can be used for energy conservation and carbon reduction in the construction field, and has great energy conservation and carbon reduction potential in climate zones where refrigeration demand is the main demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 : The construction process of the reflective heat-insulating aerogel coating of the present invention.

[0040] Figure 2: The reflective heat-insulating aerogel coating of the present invention is applied in reflective heat-insulating and cooling of factory roofs. DETAILED DESCRIPTION

[0041] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0042] As mentioned above, reflective thermal insulation coatings are made from a synthetic resin base, supplemented with functional pigments, fillers, and additives, resulting in a high solar reflectance. Silica aerogels have excellent thermal insulation properties and can be used in reflective thermal insulation coatings. However, silica aerogels tend to agglomerate in coatings and have poor dispersion in water-based coatings, which reduces the coating's thermal insulation performance. Furthermore, silica aerogels absorb moisture, causing their skeleton structure to expand and rupture when exposed to water, which can also reduce the coating's weather resistance.

[0043] In view of this, the present invention has developed a new reflective heat-insulating aerogel coating. By selecting appropriate resins, graded hollow glass microspheres, functional fillers, and modifying silica aerogel, the present invention produces a coating material with excellent reflective heat-insulating properties.

[0044] The reflective heat-insulating aerogel coating of the present invention is made of a film-forming emulsion, modified silica aerogel, graded hollow glass microspheres, functional fillers, additives and deionized water; wherein:

[0045] The film-forming emulsion is the main component of the coating, carrying the functional ingredients in the coating. After film formation, it achieves adhesion to the substrate. Therefore, the selection of the film-forming emulsion is extremely critical. The present invention uses a water-soluble epoxy resin, a silicone acrylic emulsion, and a tert-fluoro emulsion as the film-forming emulsion. The water-soluble epoxy resin can be diluted arbitrarily with water and can be cured to form a film at room temperature. The addition of the silicone acrylic emulsion and the tert-fluoro emulsion introduces tert-carbonic acid macromolecules, which synergize with fluorine and silicon atoms to significantly improve the weather resistance, acid and alkali resistance, and stain resistance of the film-forming coating.

[0046] The present invention first hydrophobically modifies the silica aerogel and then performs secondary modification using alkylbenzenesulfonic acid / glycerol, so that the interior of the modified silica aerogel is hydrophobic, and the exterior is modified by a hydrophilic solvent and a surfactant, thereby improving the compatibility of the silica aerogel with an aqueous emulsion.

[0047] Hollow glass microspheres have a large specific surface area, allowing light to reflect multiple times when it strikes the coating surface, increasing the coating's reflectivity. This invention further combines two hollow glass microspheres of different particle sizes, using large hollow glass microspheres as the main component and smaller hollow glass microspheres as filler, effectively increasing the coating's reflectivity.

[0048] Functional fillers are primarily used to reflect solar radiation in the visible and near-infrared bands for thermal insulation. The refractive index ratio of the functional filler to the resin in the film-forming emulsion affects the reflectivity of the resulting coating. In conjunction with the film-forming emulsion used in this invention, titanium dioxide, zinc oxide, and potassium titanate whiskers are selected as functional fillers, effectively improving the coating's reflective properties.

[0049] In summary, the reflective thermal insulation aerogel coating of the present invention improves the compatibility of silica aerogel in a water-based resin system by modifying silica aerogel; improves the reflectivity of the coating by adding hollow glass microspheres of different sizes; improves the weather resistance, acid and alkali resistance and stain resistance of the coating after film formation by compounding water-soluble epoxy resin, silicone acrylic emulsion and tert-fluoro emulsion as a film-forming emulsion; the film-forming emulsion, modified silica aerogel and functional filler can be cross-linked to form a three-dimensional structure, so that the modified silica aerogel and functional filler are evenly dispersed in the coating, forming many reflective interfaces inside the coating, so that part of the heat entering the coating is further reflected and scattered secondary, and the heat is kept out of the coating, thereby improving the thermal insulation effect of the coating.

[0050] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific embodiments.

[0051] The test materials used in the examples and comparative examples of the present invention are all conventional test materials in the field and can be purchased through commercial channels.

[0052] Water-based epoxy resin GEM07 was purchased from Shanghai Lujia Waterborne Coatings Co., Ltd. The silicone-acrylic emulsion was SD-528, purchased from Jiangsu Shengda New Materials Technology Co., Ltd.; the tert-fluoroelastomer was SD-628, also purchased from Jiangsu Shengda New Materials Technology Co., Ltd. Hollow glass microspheres HL25 and HM10 were purchased from Zhengzhou Shenglait Hollow Microsphere New Materials Co., Ltd. Dispersants, wetting agents, defoamers, and thickeners were purchased from Shanghai Ziyi Chemical Co., Ltd. Potassium titanate whiskers were purchased from Maclean, product number P790560. Alkylbenzenesulfonic acid, CAS number 27176-87-0.

[0053] Example 1: Preparation of reflective thermal insulation aerogel coating

[0054] 1. Raw material composition (by weight):

[0055] 50 parts of film-forming emulsion, 10 parts of modified silica aerogel, 8 parts of graded hollow glass microspheres, 6 parts of functional filler, 2 parts of additives, and 24 parts of deionized water; of which:

[0056] The film-forming emulsion is composed of water-based epoxy resin, silicone acrylic emulsion and tert-fluoro emulsion in a weight ratio of 5:1:1;

[0057] The preparation method of modified silica aerogel is as follows:

[0058] TEOS, ethanol, and deionized water were mixed in a molar ratio of 1:8:4, and the pH was adjusted to 3 with dilute hydrochloric acid. The mixture was hydrolyzed for 2 h. The pH was then adjusted to 6.5, and the mixture was stirred evenly. The mixture was sealed and allowed to stand until a gel was formed. The gel was aged at 50°C for 24 h, and then solvent exchanged (exchanged with anhydrous ethanol three times, and then n-hexane was added to exchange the ethanol in the skeleton structure) to obtain a wet gel.

[0059] The wet gel was placed in a trimethylchlorosilane / n-hexanol mixed solution (the volume ratio of trimethylchlorosilane to n-hexanol in the mixed solution was 1:1) for 12 hours, subjected to a primary modification, and dried to obtain a hydrophobic silica aerogel;

[0060] The hydrophobic silica aerogel was placed in an alkylbenzenesulfonic acid / glycerol mixed solution (the volume ratio of alkylbenzenesulfonic acid to glycerol in the mixed solution was 1:1) for 12 hours, subjected to secondary modification, and dried to prepare a modified silica aerogel.

[0061] Graded hollow glass microspheres are composed of hollow glass microspheres HL25 and hollow glass microspheres HM10 in a weight ratio of 5:1.

[0062] The functional filler is composed of titanium dioxide, zirconium oxide and potassium titanate whiskers in a weight ratio of 1:1:1.

[0063] The additive is composed of ZY-9401 water-based dispersant, ZY-2648 silicone wetting agent, ZY-5020 polyurethane associative thickener and ZY-6310 silicone defoamer for water-based coatings in a weight ratio of 1:1:1:1.

[0064] 2. Preparation method:

[0065] (1) Deionized water and the additive were mixed at a low speed (100 r / min) for 15 min, and then the modified silica aerogel, graded hollow glass microspheres and functional fillers were added and dispersed at a high speed (1000 r / min) for 30 min to obtain a mixed slurry;

[0066] (2) Adding the film-forming emulsion to the mixed slurry, stirring at a low speed (100 r / min) for 30 minutes, thereby preparing a reflective heat-insulating aerogel coating.

[0067] Example 2: Preparation of reflective thermal insulation aerogel coating

[0068] 1. Raw material composition (by weight):

[0069] 40 parts of film-forming emulsion, 15 parts of modified silica aerogel, 5 parts of graded hollow glass microspheres, 8 parts of functional filler, 1 part of additive, and 31 parts of deionized water;

[0070] The film-forming emulsion, modified silica aerogel, graded hollow glass microspheres, functional fillers and additives are the same as those in Example 1.

[0071] 2. Preparation method:

[0072] The reflective heat-insulating aerogel coating was prepared according to the method of Example 1.

[0073] Example 3: Preparation of reflective thermal insulation aerogel coating

[0074] 1. Raw material composition (by weight):

[0075] 60 parts of film-forming emulsion, 5 parts of modified silica aerogel, 8 parts of graded hollow glass microspheres, 4 parts of functional filler, 3 parts of additives, and 20 parts of deionized water;

[0076] The film-forming emulsion, modified silica aerogel, graded hollow glass microspheres, functional fillers and additives are the same as those in Example 1.

[0077] 2. Preparation method:

[0078] The reflective heat-insulating aerogel coating was prepared according to the method of Example 1.

[0079] Comparative Example 1:

[0080] The difference from Example 1 is that the "modified silica aerogel" in Example 1 is replaced by "hydrophobic silica aerogel obtained by one modification".

[0081] Comparative Example 2:

[0082] The difference from Example 1 is that the "film-forming emulsion" in Example 1 is replaced by "water-based epoxy resin".

[0083] Comparative Example 3:

[0084] The difference from Example 1 is that the "film-forming emulsion" in Example 1 is replaced by "aqueous epoxy resin and silicone acrylic emulsion in a weight ratio of 5:1".

[0085] Comparative Example 4:

[0086] The difference from Example 1 is that the "film-forming emulsion" in Example 1 is replaced by "aqueous epoxy resin and tert-fluoro emulsion in a weight ratio of 5:1".

[0087] Test Example 1: Basic Performance Evaluation of Reflective Thermal Insulation Coatings

[0088] The reflective thermal insulation aerogel coatings prepared in Examples 1-3 of the present invention belong to reflective thermal insulation flat coatings in reflective thermal insulation coatings for buildings. The basic performance requirements of the reflective thermal insulation aerogel coatings prepared in Examples 1-3 were examined according to GB / T25261-2018 "Reflective Thermal Insulation Coatings for Buildings".

[0089] The reflective thermal insulation aerogel coatings prepared in Examples 1-3 all meet the performance requirements for "reflective thermal insulation flat coatings" in GB / T25261-2018 "Reflective Thermal Insulation Coatings for Buildings"; the coating appearance test is normal, the alkali resistance test is normal, the water resistance test is normal, and the coating temperature change resistance test is normal.

[0090] Test Example 2: Investigation of the thermal insulation performance and stain resistance of reflective thermal insulation coatings

[0091] Thermal insulation performance and anti-fouling performance are two properties of the reflective thermal insulation coating that the present invention focuses on. Therefore, the present invention investigates the thermal insulation performance and anti-fouling performance of the coatings prepared in Example 1 and Comparative Examples 1-4.

[0092] 1. Test method:

[0093] (1) Cooling temperature difference test:

[0094] According to the method of Appendix B “Determination of the thermal insulation temperature difference with the reference blackboard” of GB / T25261-2018 “Reflective thermal insulation coatings for construction”, the thermal insulation temperature difference of the coatings prepared in Example 1 and Comparative Examples 1 to 4 was tested.

[0095] (2) Anti-fouling test:

[0096] According to the test method for stain resistance of exterior wall coatings in GB / T 9780-2013 "Test method for stain resistance of architectural coatings", the test was carried out according to "5.4 Brushing Method" to test the stain resistance of the coatings prepared in Example 1 and Comparative Examples 1 to 4.

[0097] The stain resistance of exterior wall paint coating is calculated according to formula (1):

[0098]

[0099] Where:

[0100] X外 is the reflection coefficient decrease rate of the coating;

[0101] A is the initial average reflectance of the coating;

[0102] B is the average reflectance of the coating after the stain test.

[0103] 2. Test results:

[0104] The performance of reflective thermal insulation coatings is shown in Table 1.

[0105] Table 1: Performance test results of reflective thermal insulation coatings

[0106] coating Insulation temperature difference (℃) Coating reflectivity decrease rate (%) Example 1 33.8 32.58 Comparative Example 1 25.4 46.32 Comparative Example 2 24.8 60.50 Comparative Example 3 26.3 52.42 Comparative Example 4 27.2 54.15

[0107] The results show that the secondary modification of silica aerogel and the raw material composition of the film-forming emulsion will affect the thermal insulation performance and stain resistance of the reflective thermal insulation coating; the combination of silicone acrylic emulsion, tert-fluoro emulsion and water-based epoxy resin as a film-forming emulsion has a synergistic effect on improving the thermal insulation performance and stain resistance of the reflective thermal insulation coating.

[0108] Application examples:

[0109] The reflective heat-insulating aerogel coating prepared in Example 1 of the present invention was applied to the roof of a factory building for heat insulation and cooling.

[0110] The construction process of the reflective heat-insulating aerogel coating of the present invention is as follows Figure 1 As shown, first clean the area to be sprayed, and then spray after cleaning. The spray thickness is about 0.1mm each time, and generally spray twice, depending on the specific working conditions. After all the spraying is completed, the surface must be smooth and flat, without bubbles, leaks, burrs, or sagging, with uniform thickness and color. Specific construction photos are as follows Figure 2 shown.

[0111] After testing, it was found that spraying the reflective heat-insulating aerogel coating of the present invention on the roof of a factory building had a good heat-insulating and cooling effect, which could avoid or reduce the use of air conditioning in summer, thus achieving the effect of energy saving and carbon reduction.

[0112] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A reflective heat-insulating aerogel coating, characterized in that: The composition comprises the following components in parts by weight: 40-60 parts of film-forming emulsion, 5-15 parts of modified silica aerogel, 5-10 parts of graded hollow glass microspheres, 4-8 parts of functional filler, 1-3 parts of additives, and 20-40 parts of deionized water; The film-forming emulsion is composed of water-based epoxy resin, silicone acrylic emulsion and tert-fluoro emulsion in a weight ratio of 5:1:1; The modified silica aerogel is prepared by the following method: Mix ethyl orthosilicate, ethanol, and deionized water in a molar ratio of 1:8:4, adjust the pH to 2-4 with dilute hydrochloric acid, and hydrolyze for 1-3 hours; then adjust the pH to 6-7, stir evenly, seal, and let stand until a gel is formed; age the gel, and then perform solvent replacement to obtain a wet gel; The wet gel is placed in a trimethylchlorosilane / n-hexanol mixed solution for a first modification and dried to obtain a hydrophobic silica aerogel; The hydrophobic silica aerogel is placed in an alkylbenzenesulfonic acid / glycerol mixed solution for secondary modification, and then dried to prepare a modified silica aerogel; The graded hollow glass microspheres are composed of hollow glass microspheres HL25 and hollow glass microspheres HM10 in a weight ratio of 5:1; The functional filler is composed of titanium dioxide, zirconium oxide and potassium titanate whiskers in a weight ratio of 1:1:1; The auxiliary agent is composed of a dispersant, a wetting agent, a defoaming agent and a thickener in a weight ratio of 1:1:1:

1.

2. The method for preparing the reflective heat-insulating aerogel coating according to claim 1, characterized in that: The following steps are involved: (1) Mixing deionized water and the additives at a low speed for 10-20 minutes, then adding the modified silica aerogel, graded hollow glass microspheres and functional fillers, and stirring and dispersing at a high speed for 20-40 minutes to obtain a mixed slurry; (2) Adding the film-forming emulsion to the mixed slurry and stirring at a low speed for 20-40 minutes to prepare the reflective heat-insulating aerogel coating.

3. Use of the reflective heat-insulating aerogel coating according to claim 1 in heat insulation and cooling of building exterior surfaces.

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