Aerogel coating and preparation method thereof

Abstract

The invention discloses an aerogel coating and a preparation method thereof, and belongs to the technical field of aerogel paints.The aerogel coating is mainly prepared from water-borne epoxy resin, composite silicon dioxide aerogel, kieselguhr, a defoaming agent, a coalescing agent, water and the like, through mutual cooperation and combined action with other raw materials, the coating has good radiation performance and heat insulation performance and can meet the requirements of different application scenes. The composite silicon dioxide aerogel is prepared by adding nano ferric oxide, nano titanium dioxide and graphene oxide during preparation of the composite silicon dioxide aerogel, so as to form a composite compact net-shaped structure in which the silicon dioxide aerogel is filled with the nano ferric oxide, the nano titanium dioxide and the graphene oxide; due to the synergistic effect of the four materials and a formed specific composite structure, the composite silicon dioxide aerogel has good heat insulation performance and radiation performance and can be used as filler of a coating.

Description

Technical Field

[0001] The invention belongs to the technical field of aerogel coatings, and particularly relates to an aerogel coating and a preparation method thereof. Background Art

[0002] Aerogel is a low-density porous material with a highly cross-linked, continuous, three-dimensional nanoscale hollow network. Its structural properties effectively inhibit both conductive and convective heat transfer, resulting in low thermal conductivity. Oxide aerogels such as silicon oxide and zirconium oxide, as well as aerogel composites composed of other materials such as fibers, are widely used in industrial energy conservation, aerospace, and new energy vehicles.

[0003] However, oxide aerogels have a strong permeability to near-infrared thermal radiation with a wavelength of 3 to 8 μm. Therefore, oxide aerogels themselves and their composite materials have poor infrared radiation shielding capabilities at high temperatures, their thermal conductivity will increase significantly, and their thermal insulation performance will decay with temperature. Currently, in order to improve the thermal insulation effect of oxides, especially silica aerogels, at high temperatures, carbon black, TiO2, B4C, SiC and other sunscreens are often added to silica aerogels to improve their infrared radiation shielding capabilities, thereby improving their high-temperature thermal insulation capabilities. CN201680010607.5 discloses a felt containing silica aerogel and a method for preparing the same. Titanium dioxide particles are dispersed in an alkaline aqueous solution and etched. After adding water, a sunscreen dispersion is obtained. The sunscreen dispersion is then mixed with a silica precursor, and an alkaline catalyst and a polar organic solvent are added. A substrate for the felt is then added and the resultant is gelled. Finally, the surface is hydrophobized and dried to obtain the product. This patent uses an impregnation method for preparation, but the modification is complex and not suitable for large-scale production. CN202210668753.4 discloses a method for preparing a high-temperature resistant aerogel composite material and the composite material thereof. The method uses a chemical vapor deposition method to pre-load carbon black, B4C or SiC particle sunscreens on a fiber reinforcement, and then impregnates and composites with silica sol. This method requires specialized chemical vapor deposition equipment and has relatively low efficiency. CN201711316915.3 discloses an aerogel composite insulation board and a method for preparing the same. The method uses aerogel powders such as silica aerogel powder, alumina aerogel powder, zirconium oxide aerogel powder and silicon carbide aerogel powder, and sunscreen powders such as silicon carbide micropowder, zircon micropowder, titanium dioxide micropowder and carbon black. The powders are mixed with a binder and loose fibers and then molded to prepare an aerogel board. However, the product obtained by this method is generally a hard board.

[0004] Aerogel coating is a special coating that combines radiation function and thermal insulation properties. Its core mechanism lies in its special treatment of thermal radiation. This type of coating can effectively reflect and absorb thermal radiation, reducing heat dissipation to the surrounding environment. The radiant thermal insulation (coating) layer it forms can significantly reduce the transfer of heat through radiation, providing excellent thermal insulation performance, helping to improve energy efficiency and reduce energy consumption, and generally has good environmental performance. In the construction field, radiant thermal insulation layers effectively reduce indoor temperature fluctuations and improve living comfort; in the aerospace field, radiant thermal insulation layers are crucial for protecting aircraft internal equipment from damage in high-temperature environments; in addition, they are widely used in industrial production and other fields.

[0005] With the development of science and technology and the increase in its application, the requirements for coating products in the coating field are becoming higher and higher. However, among the current coating products, there are still few products that can have both good radiation performance and thermal insulation performance and can meet higher usage requirements. Therefore, the radiation performance and thermal insulation performance of coatings need to be further improved.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] In view of the shortcomings and defects of the existing technology, the present invention aims to provide an aerogel coating and a preparation method thereof, and solve the problem that the radiation performance and thermal insulation performance of the coating need to be further improved through the preparation and application of composite silica aerogel.

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

[0009] In a first aspect, an aerogel coating comprises a composite silica aerogel, titanium dioxide, diatomaceous earth, a defoamer, a film-forming aid, a water-based epoxy resin, and water; based on the total mass of the aerogel coating being 100%, the composite silica aerogel comprises 0.5 to 2.5 wt %, titanium dioxide 12 to 19 wt %, diatomaceous earth 1 to 4 wt %, a defoamer 5 to 12.5 wt %, a film-forming aid 5 to 12.5 wt %, a water-based epoxy resin 37.5 to 50 wt %, and water 12 to 25 wt %;

[0010] The preparation method of the composite silica aerogel comprises the following steps:

[0011] S1, ultrasonically mixing the sodium silicate aqueous solution with the nano-ferric oxide, nano-titanium dioxide and graphene oxide aqueous solutions, and then adding the hydrochloric acid solution and stirring to control the pH of the obtained mixed solution to 4-9;

[0012] S2, sequentially subjecting the mixed solution obtained in step S1 to wet gelation, solution replacement, aging, freezing, and drying to obtain a composite silica aerogel, forming a tight network structure in which the silica aerogel is filled with nano-ferric oxide, nano-titanium dioxide, and graphene oxide and composited with silica;

[0013] In step S1, the mass ratio of sodium silicate in the sodium silicate aqueous solution to nano-ferric oxide, nano-titanium dioxide and graphene oxide in the graphene oxide aqueous solution is 6-10:0.4-1.2:0.4-1.2:0.005-0.01.

[0014] Furthermore, in the aerogel coating, the content of the composite silica aerogel is 1.1-1.3 wt %; in step S1, the mass ratio of sodium silicate in the sodium silicate aqueous solution to nano-ferric oxide, nano-titanium dioxide and graphene oxide in the graphene oxide aqueous solution is 6-8:0.7-0.8:0.7-0.8:0.009-0.01.

[0015] Furthermore, in step S1, the pH of the mixed solution is 7-8.

[0016] Furthermore, in step S1, the concentration of the sodium silicate aqueous solution is 0.3 to 0.6 g / mL;

[0017] and / or, the concentration of the hydrochloric acid solution is 2.5 to 7.5 mol / L;

[0018] And / or, the concentration of the graphene oxide aqueous solution is 0.5-2 mg / mL.

[0019] Furthermore, in step S1, the sodium silicate aqueous solution is obtained by ultrasonically mixing sodium silicate and water for 30 to 60 minutes;

[0020] And / or, the hydrochloric acid solution is obtained by ultrasonically mixing concentrated hydrochloric acid and water for 10 to 30 minutes;

[0021] And / or, the time for ultrasonically mixing the sodium silicate aqueous solution with the nano-ferric oxide, nano-titanium dioxide and graphene oxide aqueous solutions is 10 to 30 minutes.

[0022] Furthermore, in step S2, the replacement solution is to replace the solution in the obtained wet gel with water;

[0023] and / or, the replacement solution is allowed to stand for 24 to 48 hours;

[0024] And / or, the aging temperature is 30-70°C;

[0025] And / or, the aging time is 12 to 24 hours;

[0026] And / or, the freezing time is 12 to 24 hours;

[0027] And / or, the drying temperature is -70 to -85°C;

[0028] And / or, the drying time is 48 to 50 hours.

[0029] Furthermore, the defoaming agent is one of n-butanol, silicone defoaming agent or polyether defoaming agent;

[0030] And / or, the film-forming aid is one of ethylene glycol, propylene glycol butyl ether, dodecyl alcohol ester and hydrocarbons.

[0031] In a second aspect, a method for preparing the aerogel coating described in the first aspect comprises: first, adding titanium dioxide, composite silica aerogel and diatomaceous earth to a reaction container in sequence; then, adding water and stirring for a certain period of time, and then adding a defoaming agent and a film-forming aid; finally, adding a water-based epoxy resin and stirring at high speed for a certain period of time, and then discharging the material after continuing to stir for a certain period of time, thereby preparing an aerogel coating containing the composite silica aerogel.

[0032] Furthermore, the time for adding water and stirring is 5 to 20 minutes; and / or, the time for further high-speed stirring is 10 to 30 minutes; and / or, the time for continuing stirring is 120 to 240 minutes.

[0033] In a third aspect, a coating is provided, wherein the coating is formed by coating the aerogel coating according to the first aspect or the aerogel coating prepared by the preparation method according to the second aspect.

[0034] Compared with the prior art, the present invention has the following effective effects:

[0035] (1) The composite silica aerogel coating of the present invention is mainly made of raw materials such as water-based epoxy resin, titanium dioxide, composite silica aerogel, diatomaceous earth, defoaming agent, film-forming aid and water. The specially prepared composite silica aerogel of the present invention is used as a filler, which cooperates with other raw materials to make the prepared coating have good radiation performance and thermal insulation performance, which can meet the different needs of various application scenarios.

[0036] The specially prepared composite silica aerogel of the present invention is a composite of nano-iron oxide, nano-titanium dioxide, and graphene oxide aqueous solutions with silica aerogel, which is then used as a coating filler to produce a coating with both radiation and thermal insulation properties. Specifically, during the preparation of the silica aerogel, the nano-iron oxide, nano-titanium dioxide, and graphene oxide aqueous solutions are added to the silica aerogel precursor, and the gel is composited to form a unique, tightly meshed structure in which the silica aerogel is filled with nano-iron oxide, nano-titanium dioxide, and graphene oxide and composited with silica. The synergistic effect of the four materials and the resulting specific composite structure give the composite silica aerogel excellent thermal insulation and radiation properties, making it suitable for use as a coating filler.

[0037] By adding composite silica aerogel to the coating in a specific proportion, an aerogel coating with excellent comprehensive performance can be obtained. It not only has good radiation performance and thermal insulation performance, but also has excellent adhesion and hardness.

[0038] (2) The preparation method of the aerogel coating of the present invention adopts a specific adding sequence, so that the coating can be well dispersed and is not easy to form particles or lumps, which is beneficial to the improvement of the overall performance of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 This is a process flow chart for preparing the composite silica aerogel and its coating of the present invention;

[0041] Figure 2 Graphs showing infrared test results of the coatings obtained in Application Examples 1 to 4 of the present invention (0.4 TIS-WER, 0.8 TIS-WER, 1.2 TIS-WER, and 1.6 TIS-WER) and the coatings obtained in Comparative Examples 1 to 3 (0.4 reference, 0.8 reference, and 1.2 reference);

[0042] Figure 3 The thermal insulation temperature difference performance test results of the coatings obtained in Application Examples 1 to 4 of the present invention (0.4 TIS-WER, 0.8 TIS-WER, 1.2 TIS-WER and 1.6 TIS-WER) and the coatings obtained in Application Comparative Examples 1 to 3 (0.4 reference, 0.8 reference and 1.2 reference) after 60 minutes are shown;

[0043] Figure 4 The thermal insulation temperature difference performance test results of the coating obtained in Application Example 3 of the present invention (1.2TIS-WER) and the coatings obtained in Application Examples 5 to 7 after 60 minutes;

[0044] Figure 5 This is a graph showing the emissivity test results of the coatings obtained in Application Examples 1 to 4 of the present invention (0.4 TIS-WER, 0.8 TIS-WER, 1.2 TIS-WER, and 1.6 TIS-WER) and the coatings obtained in Application Comparative Examples 1 to 3 (0.4 reference, 0.8 reference, and 1.2 reference);

[0045] Figure 6 Graph showing adhesion test results of the coatings obtained in Application Examples 1 to 4 of the present invention (0.4 TIS-WER, 0.8 TIS-WER, 1.2 TIS-WER, and 1.6 TIS-WER) and the coatings obtained in Application Comparative Examples 1 to 3 (0.4 reference, 0.8 reference, and 1.2 reference);

[0046] Figure 7 Graph showing adhesion test results of the coating (1.2TIS-WER) obtained in Application Example 3 of the present invention and the coatings obtained in Application Examples 5 to 7;

[0047] Figure 8 Graph showing the thermal conductivity test results of the coatings (0.4 TIS-WER, 0.8 TIS-WER, 1.2 TIS-WER, and 1.6 TIS-WER) obtained in Application Examples 1 to 4 of the present invention;

[0048] Figure 9 The following are scanning electron microscope images of the pure silica aerogel (a) obtained in Comparative Example 1 of the present invention scanned at 450 times magnification, and a scanning electron microscope image of the composite silica aerogel (b) obtained in Example 1 scanned at 450 times magnification;

[0049] Figure 10 These are scanning electron microscope images of the coatings obtained in Application Examples 1 to 4 of the present invention (0.4TIS-WER (a), 0.8TIS-WER (b), 1.2TIS-WER (c), 1.6TIS-WER (d)) scanned at 450 times. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described below with reference to the embodiments. The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and processes are given. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention. The scope of protection of the present invention is not limited to the following embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention.

[0051] In the examples of the present invention, process parameters not specifically specified are generally based on conventional conditions. Unless otherwise specified and / or explained, all numerical values ​​referring to component amounts are expressed as "weights or mass values ​​or ratios." Unless otherwise noted, all raw materials used in the present invention are commercially available.

[0052] In the present invention, the endpoints and any values ​​of the disclosed ranges are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered as specifically disclosed in the present invention. The effect test data of the present invention are all the average values ​​of three parallel test results.

[0053] According to a first aspect of the present invention, a method for preparing a composite silica aerogel is provided, the preparation method comprising the following steps:

[0054] S1, ultrasonically mixing the sodium silicate aqueous solution with the nano-ferric oxide, nano-titanium dioxide and graphene oxide aqueous solution, and then adding the hydrochloric acid solution and stirring to control the pH of the obtained mixed solution to 4 to 9 (such as 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5);

[0055] S2. The mixed solution obtained in step S1 is sequentially subjected to wet gelation, solution replacement, aging, freezing, and drying to obtain a composite silica aerogel.

[0056] The composite silica aerogel of the present application is a nanometer ferroferric oxide, nanometer titanium dioxide and graphene oxide composite silica aerogel. Among them, nanometer ferroferric oxide, as a material with high thermal conductivity and high heat capacity, can reduce the transfer of energy, thereby forming a thermal isolation zone in the indoor space, reducing the loss of energy, and achieving the effect of energy saving. In particular, when the external temperature is high, nanometer ferroferric oxide can also play a role in reflecting solar radiation, which helps to maintain the stability and comfort of the indoor temperature, further embodying its excellent performance in radiation heat insulation.

[0057] Nanometer titanium dioxide has excellent ultraviolet resistance, which is mainly due to its high refractive and high photoactivity. It can effectively absorb, reflect and scatter ultraviolet rays, especially has a significant barrier effect on medium and long wave ultraviolet rays. This property makes nanometer titanium dioxide a superior ultraviolet protective agent, which can significantly improve the ultraviolet resistance of the coating.

[0058] Graphene oxide is a two-dimensional carbon nanomaterial, its structure is similar to graphene, but it introduces oxygen-containing functional groups on the surface and edges. These functional groups change the electronic properties of graphene, and also have a significant impact on its thermal performance. Specifically, the layered structure of graphene oxide and oxygen-containing functional groups can effectively hinder the transfer of heat, thereby imparting its thermal insulation performance. Oxygen-containing functional groups form thermal resistance in the material, slowing down the speed of heat transfer in the material. In addition, the layered structure of graphene oxide also increases the path length of heat transfer, further improving its thermal insulation effect.

[0059] Silica aerogel can be applied in the field of thermal insulation due to the nanopores and three-dimensional network structure of silica aerogel. The unique nanopore structure of silica aerogel restricts the free flow of air molecules and inhibits the convective conduction of air. The three-dimensional network structure of nanometer ferroferric oxide, nanometer titanium dioxide and graphene oxide filling and compounding forms a reflective and refractive surface of thermal radiation, which can maximize the inhibition of radiation heat conduction. Therefore, the use of composite silica aerogel with excellent thermal insulation performance in thermal insulation coating can greatly improve the thermal insulation effect of the coating / film. Generally, the synthesis of silica aerogel is as follows:

[0060] Sodium silicate, also known as water glass, is also known as sodium water glass (Na2O·nSiO2). Water glass is used by many researchers as a silica source for aerogel due to its low cost. With water glass as the source and hydrochloric acid as the catalyst, silica aerogel is prepared. The silica aerogel will first undergo a hydrolysis reaction, followed by a condensation reaction. After the completion of the condensation reaction, a gel is obtained. During the research and development process of the present application, it is found that there are mainly three influencing factors:

[0061] 1. As the amount of water increases, the gel time decreases linearly, consistent with the fact that the hydrolysis rate of waterglass is affected by the amount of water. Water, as a product of the polycondensation reaction, also gradually prolongs the gel time. Studies have shown that a relatively large increase in the amount of water has a significant adverse effect on the finished product's properties (such as density). It is believed that increased water content in the gel increases the difficulty of subsequent processing and can significantly increase shrinkage. Therefore, a series of experiments determined that the optimal volume ratio of waterglass to water is approximately 1:3.

[0062] 2. In the pH range of 4 to 9, the gelation time is inversely proportional to the pH value of the solution. This is because under acidic conditions, the hydrolysis reaction is more favorable, and the polycondensation reaction rate will be inhibited to a certain extent. The sol is difficult to condense into agglomerates, resulting in a lower skeleton structure strength and greater gel shrinkage. Therefore, the gelation time is longer and the density is correspondingly higher. When the solution is alkaline, that is, when the pH is greater than 9, the polycondensation reaction is more favorable, and the corresponding hydrolysis reaction rate will decrease. At this time, the solution will gel rapidly, and the sol monomers will form clusters with a higher density. In order to balance the polycondensation reaction and the hydrolysis reaction, a pH value of 7 to 8 is optimal.

[0063] 3. Newly formed silica aerogels have only a few siloxane bonds connecting their secondary particles, resulting in a fragile structure. During aging, the connection points in the neck regions between particles expand, strengthening the gel skeleton structure. Aging temperature is closely linked to gelation time. Molecular motion accelerates dramatically with increasing temperature, significantly increasing the probability of intermolecular collisions and accelerating the gel's polycondensation reaction.

[0064] In summary, the present invention further obtained the optimal preparation method of composite silica aerogel by exploring the above three influencing factors:

[0065] First, add 140-280 g of sodium silicate to a clean 500 mL volumetric flask, then add deionized water to the scale line, and ultrasonicate the solution for 30-60 minutes to fully mix the deionized water and sodium silicate to obtain a sodium silicate aqueous solution with a concentration of 0.3-0.6 g / mL.

[0066] Secondly, add 20-65 mL of concentrated hydrochloric acid to a clean 100 mL volumetric flask, then add deionized water to the scale line, and ultrasonicate the solution for 10-30 minutes to fully mix the deionized water and hydrochloric acid to obtain a hydrochloric acid solution with a concentration of 2.5-7.5 mol / L.

[0067] Finally, according to the mass ratio of sodium silicate in sodium silicate aqueous solution to nano-iron oxide, nano-titanium dioxide and graphene oxide in graphene oxide aqueous solution of 6-10:0.4-1.2:0.4-1.2:0.005-0.01, sodium silicate aqueous solution was taken in a clean beaker in turn, and then nano-iron oxide, titanium dioxide and graphene oxide aqueous solution were added. The solution was ultrasonicated for 10-30 minutes by ultrasonic instrument to mix the drugs evenly, and then 5-20 mL of hydrochloric acid solution was added. The mixture was stirred evenly and allowed to stand for wet gelation of the composite silica; the wet gel was taken out and placed in a 1000 mL beaker, 500-1000 mL of deionized water was added to replace the solution in the wet gel, and the mixture was allowed to stand for 24-48 hours. The wet gel was taken out and aged at 30-70°C for 12-24 hours to obtain a gel; the gel was then frozen for 12-24 hours, and after freezing, it was placed in a vacuum freeze dryer at -70--85°C for freeze drying for 48-50 hours to obtain a composite silica aerogel.

[0068] Therefore, as an optional embodiment of the composite silica aerogel of the present invention, in step S1, the pH of the mixed solution is 7 to 8, typically but not limited to 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, etc.

[0069] As an optional embodiment of the composite silica aerogel of the present invention, in step S1, the mass ratio of sodium silicate in the sodium silicate aqueous solution to nano-iron trioxide, nano-titanium dioxide and graphene oxide in the graphene oxide aqueous solution is 6-10:0.4-1.2:0.4-1.2:0.005-0.01; in parts by mass, the mass fraction of the sodium silicate is typically but not limited to 6.1, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 9.9, etc., the mass fraction of the nano-iron trioxide is typically but not limited to 0.45, 0.5, 0.55, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, etc., and the mass fraction of the nano-titanium dioxide is typically but not limited to 0. The mass ratio of the graphene oxide is typically but not limited to 0.45, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.15, etc., and the mass ratio of the graphene oxide is typically but not limited to 0.006, 0.007, 0.008, 0.009, etc. According to the above-mentioned mass ratio range, the mass ratio of the sodium silicate in the sodium silicate aqueous solution to the nano-iron oxide, nano-titanium dioxide and graphene oxide in the aqueous solution is selected; preferably, the mass ratio of the sodium silicate in the sodium silicate aqueous solution to the nano-iron oxide, nano-titanium dioxide and graphene oxide in the aqueous solution is 6-8: 0.7-0.8: 0.7-0.8: 0.009-0.01.

[0070] In composite silica aerogels, the ratios of several raw materials must be appropriately controlled. Excessive amounts of nano-ferric oxide (Fe2O3) can lead to decreased porosity and increased density in the aerogel, affecting its low thermal conductivity. TiO2 nanoparticles easily agglomerate, and excessive additions can disrupt the aerogel's mesoporous structure and reduce its specific surface area. While moderate amounts of graphene oxide can increase the specific surface area, excessive amounts can actually reduce it and disrupt the aerogel's nanoporous structure, increasing heat conduction paths and weakening its thermal insulation properties.

[0071] and / or, the concentration of the sodium silicate aqueous solution is 0.3-0.6 g / mL, typically but not limited to 0.31 g / mL, 0.35 g / mL, 0.4 g / mL, 0.45 g / mL, 0.5 g / mL, 0.55 g / mL, 0.59 g / mL, etc.;

[0072] and / or, the concentration of the hydrochloric acid solution is 2.5 to 7.5 mol / L (M), typically but not limited to 2.6 M, 3 M, 3.5 M, 4 M, 4.5 M, 5 M, 5.5 M, 6 M, 6.5 M, 7 M, 7.4 M, etc.;

[0073] And / or, the concentration of the graphene oxide aqueous solution is 0.5-2 mg / mL, typically but not limited to 0.6 mg / mL, 0.8 mg / mL, 1 mg / mL, 1.2 mg / mL, 1.4 mg / mL, 1.6 mg / mL, 1.8 mg / mL, etc.

[0074] As an optional embodiment of the composite silica aerogel of the present invention, in step S1, the sodium silicate aqueous solution is obtained by ultrasonically mixing sodium silicate and water for 30 to 60 minutes (e.g., 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, etc.);

[0075] And / or, the hydrochloric acid solution is obtained by ultrasonically mixing concentrated hydrochloric acid and water for 10 to 30 minutes (e.g., 15 minutes, 20 minutes, 25 minutes, etc.);

[0076] And / or, the time for ultrasonically mixing the sodium silicate aqueous solution with the nano-ferric oxide, nano-titanium dioxide and graphene oxide aqueous solutions is 10 to 30 minutes (such as 15 minutes, 20 minutes, 25 minutes, etc.).

[0077] As an optional embodiment of the composite silica aerogel of the present invention, in step S2, the replacement solution is a solution in the wet gel obtained by replacing it with water; further, the amount of water used in the replacement solution is 500-1000 mL (such as 510 mL, 550 mL, 60 mL, 650 mL, 70 mL, 750 mL, 80 mL, 850 mL, 90 mL, 950 mL, etc.); and / or, the standing time of the replacement solution is 24-48 h (such as 25 h, 30 h, 35 h, 40 h, 45 h, 47 h, etc.);

[0078] and / or, the aging temperature is 30-70° C. (e.g., 31° C., 35° C., 40° C., 45° C., 50° C., 55° C., 60° C., 65° C., 69° C., etc.);

[0079] And / or, the aging time is 12 to 24 hours (such as 13 hours, 15 hours, 17 hours, 19 hours, 21 hours, 23 hours, etc.);

[0080] And / or, the freezing time is 12 to 24 hours (such as 13 hours, 15 hours, 17 hours, 19 hours, 21 hours, 23 hours, etc.);

[0081] And / or, the drying temperature is -70 to -85°C (e.g., -71°C, -73°C, -75°C, -77°C, -79°C, -81°C, -83°C, etc.);

[0082] And / or, the drying time is 48 to 50 hours (such as 48.5 hours, 49 hours, 49.5 hours, etc.).

[0083] According to the first aspect of the present invention, there is also provided an aerogel coating comprising the aforementioned composite silica aerogel.

[0084] As an optional embodiment of the aerogel coating of the present invention, the aerogel coating further includes titanium dioxide, diatomaceous earth, a defoaming agent, a film-forming aid, a water-based epoxy resin and water, wherein, based on the total mass of the aerogel coating being 100%, the composite silica aerogel is 0.5-2.5wt% (such as 0.6wt%, 0.8wt%, 1wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, etc.), titanium dioxide is 12-19wt% (such as 13wt%, 14wt%, 15wt%, 16wt%, 17wt%, 18wt%, etc.), and diatomaceous earth is 100%. 1-4wt% (such as 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, etc.), defoamer 5-12.5wt% (such as 6wt%, 8wt%, 10wt%, 12wt%, etc.), film-forming aid 5-12.5wt% (such as 6wt%, 8wt%, 10wt%, 12wt%, etc.), water-based epoxy resin 37.5-50wt% (such as 38wt%, 40wt%, 42wt%, 44wt%, 46wt%, 48wt%, etc.), water 12-25wt% (such as 13wt%, 15wt%, 17wt%, 19wt%, 21wt%, 23wt%, etc.).

[0085] As an optional embodiment of the aerogel coating of the present invention, in the aerogel coating, the mass percentage of the composite silica aerogel is 0.7-1.8 wt%, preferably 0.7-1.3 wt%, and more preferably 1.1-1.3 wt%.

[0086] As an optional embodiment of the aerogel coating of the present invention, the defoamer is one of n-butanol, silicone defoamer or polyether defoamer;

[0087] And / or, the film-forming aid is one of ethylene glycol, propylene glycol butyl ether, dodecyl alcohol ester and hydrocarbons.

[0088] According to a second aspect of the present invention, a method for preparing the aerogel coating is provided, comprising: first, adding titanium dioxide, composite silica aerogel and diatomaceous earth to a reaction container in sequence; then adding water and stirring for a certain time, such as 5 to 20 minutes (specifically, 6 minutes, 10 minutes, 15 minutes, 17 minutes, etc.), and then adding a defoamer and a film-forming aid; finally, stirring at high speed for a certain time, such as 10 to 30 minutes (specifically, 15 minutes, 20 minutes, 25 minutes, etc.), and then adding a water-based epoxy resin, continuing to stir for a certain time, such as 120 to 240 minutes (specifically, 140 minutes, 180 minutes, 220 minutes, etc.), and then discharging the material, thereby obtaining an aerogel coating containing the composite silica aerogel.

[0089] The aerogel coating of the present invention is a radiation-reflecting thermal insulation coating. By adding composite silica aerogel, the coating exhibits excellent radiation-reflecting thermal insulation properties. Since nano-ferric oxide, nano-titanium dioxide, and graphene oxide are composited during the preparation of the silica aerogel, the nanopores of the silica aerogel are filled with these three nanomaterials, which combine with the silica to form a network structure. This composite network structure forms reflective and refractive surfaces for thermal radiation, minimizing radiative heat conduction. Therefore, the use of composite silica aerogel, which exhibits excellent thermal insulation properties, in thermal insulation coatings significantly enhances the thermal insulation effect of the coating.

[0090] The preparation method of the aerogel coating of the present invention adopts a specific adding sequence, so that the coating can be well dispersed and is not easy to form particles or lumps, which is beneficial to improving the overall performance of the coating.

[0091] According to a third aspect of the present invention, a coating is provided, which is formed by coating the aerogel coating according to the first aspect or the aerogel coating prepared by the preparation method according to the second aspect.

[0092] The present invention will be described in further detail below with reference to specific embodiments.

[0093] Example 1

[0094] The synthesis process of composite silica aerogel is as follows Figure 1 As shown, the preparation method specifically comprises the following steps:

[0095] The first step is to prepare a sodium silicate aqueous solution: add 175g of sodium silicate to a clean 500mL volumetric flask, then add deionized water to the scale line, and sonicate the solution in an ultrasonic instrument for 60 minutes to fully mix the deionized water and sodium silicate to obtain a 0.35g / mL sodium silicate aqueous solution.

[0096] The second step is to prepare the hydrochloric acid solution: add 20.83 mL of concentrated hydrochloric acid to a clean 100 mL volumetric flask, then add deionized water to the scale line, and ultrasonicate the solution for 30 minutes to fully mix the deionized water and hydrochloric acid to obtain a hydrochloric acid solution with a concentration of 2.5 mol / L.

[0097] The third step is to take 20mL of sodium silicate aqueous solution into a clean beaker, add 5mmol (0.798g) of nano-ferric oxide and 10mmol (0.799g) of nano-titanium dioxide, and then add 5mL of 2mg / mL graphene oxide aqueous solution. Ultrasonicate the solution for 30min in an ultrasonic instrument to mix the drugs evenly, then add 10mL of hydrochloric acid solution and stir evenly to control the pH of the obtained mixed solution to about 7. Let it stand for the composite silica wet gelation, take out the wet gel, place it in a 1000mL beaker, add 1000mL of deionized water to replace the solution in the wet gel, let it stand for 48h, take out the wet gel, age it at 70℃ for 24h to obtain a gel, and then freeze the gel for 24h. After freezing, put it into a vacuum freeze dryer and freeze-dry it at -70℃ for 48h to obtain a composite silica aerogel.

[0098] Example 2

[0099] The only difference from Example 1 is the third step:

[0100] The third step is to take 24 mL of sodium silicate aqueous solution into a clean beaker, add 4 mmol (0.639 g) of nano-ferric oxide and 8 mmol (0.639 g) of nano-titanium dioxide, and then add 4 mL of 2 mg / mL graphene oxide aqueous solution. The solution is ultrasonicated for 30 minutes in an ultrasonic instrument to mix the drugs evenly, and then 12 mL of hydrochloric acid solution is added and stirred evenly to control the pH of the obtained mixed solution to be about 7. The composite silica is allowed to stand for wet gelation, the wet gel is taken out, placed in a 1000 mL beaker, 1000 mL of deionized water is added to replace the solution in the wet gel, and the solution is allowed to stand for 48 hours. The wet gel is taken out and aged at 70°C for 24 hours to obtain a gel, and then the gel is frozen for 24 hours. After freezing, it is placed in a vacuum freeze dryer and freeze-dried at -70°C for 48 hours to obtain a composite silica aerogel.

[0101] Example 3

[0102] The only difference from Example 1 is the third step:

[0103] The third step is to take 28 mL of sodium silicate aqueous solution into a clean beaker, add 3 mmol (0.479 g) of nano-ferric oxide and 6 mmol (0.479 g) of nano-titanium dioxide, and then add 3 mL of 2 mg / mL graphene oxide aqueous solution. The solution is ultrasonicated for 30 minutes in an ultrasonic instrument to mix the drugs evenly, and then 14 mL of hydrochloric acid solution is added and stirred evenly to control the pH of the obtained mixed solution to be about 7. The composite silica is allowed to stand for wet gelation, the wet gel is taken out, placed in a 1000 mL beaker, 1000 mL of deionized water is added to replace the solution in the wet gel, and the solution is allowed to stand for 48 hours. The wet gel is taken out and aged at 70°C for 24 hours to obtain a gel, and then the gel is frozen for 24 hours. After freezing, it is placed in a vacuum freeze dryer and freeze-dried at -70°C for 48 hours to obtain a composite silica aerogel.

[0104] Example 4

[0105] The only difference from Example 1 is the third step:

[0106] The third step is to take 20mL of sodium silicate aqueous solution into a clean beaker, add 6.25mmol (1g) of nano-ferric oxide and 12.5mmol (1g) of nano-titanium dioxide, and then add 5mL of graphene oxide aqueous solution with a concentration of 2mg / mL. The solution is ultrasonicated for 30min in an ultrasonic instrument to mix the drugs evenly, and then 14mL of hydrochloric acid solution is added and stirred evenly to control the pH of the obtained mixed solution to be about 7. The composite silica is allowed to stand for wet gelation, the wet gel is taken out, and placed in a 1000mL beaker. 1000mL of deionized water is added to replace the solution in the wet gel, and the mixture is allowed to stand for 48h. The wet gel is taken out and aged at 70°C for 24h to obtain a gel. The gel is then frozen for 24h. After freezing, it is placed in a vacuum freeze dryer and freeze-dried at -70°C for 48h to obtain a composite silica aerogel.

[0107] Example 5

[0108] The only difference from Example 1 is the third step:

[0109] The third step is to take 20mL of sodium silicate aqueous solution into a clean beaker, add 6.25mmol (1g) of nano-ferric oxide and 10mmol (0.799g) of nano-titanium dioxide, and then add 5mL of graphene oxide aqueous solution with a concentration of 2mg / mL. The solution is ultrasonicated for 30min in an ultrasonic instrument to mix the drugs evenly, and then 14mL of hydrochloric acid solution is added and stirred evenly to control the pH of the obtained mixed solution to be about 7. The composite silica is allowed to stand for wet gelation, the wet gel is taken out, placed in a 1000mL beaker, 1000mL of deionized water is added to replace the solution in the wet gel, and the solution is allowed to stand for 48h. The wet gel is taken out and aged at 70°C for 24h to obtain a gel, and then the gel is frozen for 24h. After freezing, it is placed in a vacuum freeze dryer and freeze-dried at -70°C for 48h to obtain a composite silica aerogel.

[0110] Example 6

[0111] The only difference from Example 1 is the third step:

[0112] The third step is to take 20mL of sodium silicate aqueous solution into a clean beaker, add 5mmol (0.798g) of nano-ferric oxide and 12.5mmol (1g) of nano-titanium dioxide, and then add 5mL of 2mg / mL graphene oxide aqueous solution. Ultrasonicate the solution for 30min in an ultrasonic instrument to mix the drugs evenly, then add 14mL of hydrochloric acid solution and stir evenly to control the pH of the obtained mixed solution to about 7. Let it stand for the composite silica wet gelation, take out the wet gel, place it in a 1000mL beaker, add 1000mL of deionized water to replace the solution in the wet gel, let it stand for 48h, take out the wet gel, age it at 70℃ for 24h to obtain a gel, and then freeze the gel for 24h. After freezing, put it into a vacuum freeze dryer and freeze-dry it at -70℃ for 48h to obtain a composite silica aerogel.

[0113] Application Examples 1-4

[0114] The preparation process of aerogel coating containing composite silica aerogel is as follows Figure 1As shown, the preparation method specifically includes the following: first, 15 g of titanium dioxide with a particle size of 0.2-0.3 μm, 0.4-1.6 g of the composite silica aerogel of Example 1, and 3 g of diatomite are sequentially poured into a three-necked flask, 10 mL of deionized water is then added, the stirrer is turned on, and stirring is performed for 20 min, 4 mL of antifoaming agent n-butanol and 4 mL of film-forming aid ethylene glycol are then added, stirring is performed at high speed for 30 min, 38 mL of water-based epoxy resin (water-based epoxy resin, purchased from Shenzhen City Yitian Chemical Co., Ltd., model F0707, epoxy equivalent g / eq 400-800, 25°C rotational viscosity <1000 mPa·S, solid content 50±3%, pH value 5-6) is then added, and stirring is performed at low speed for 120 min, and the composite silica aerogel aerogel coating is then poured out, thereby being prepared. The composite silica aerogel content in the aerogel coatings of Application Examples 1-4 can be seen from Table 1 below:

[0115] Table 1

[0116]

[0117] Note: In Table 1, the numerical value before the sample name represents the mass of the composite silica aerogel added in the coating sample.

[0118] The English of the sample name represents: T represents nanometer titanium dioxide, I represents nanometer ferric oxide, S represents silica aerogel, and WER represents water-based epoxy resin.

[0119] Application Examples 5-7

[0120] Except that the composite silica aerogel added is different from that of Application Example 3, the other steps and component amounts in the preparation of the aerogel coating are the same as those of Application Example 3. In the application examples, the composite silica aerogel added in Application Example 5 is the composite silica aerogel prepared in Example 4, the composite silica aerogel added in Application Example 6 is the composite silica aerogel prepared in Example 5, and the composite silica aerogel added in Application Example 7 is the composite silica aerogel prepared in Example 6. The amount of the composite silica aerogel used in the preparation of the coating in Application Examples 5-7 is 1.2 g.

[0121] Comparative Example 1

[0122] Pure silica aerogel, which is different from Example 1 only in that no nanometer ferric oxide, nanometer titanium dioxide, and graphene oxide are added for compounding.

[0123] The preparation method specifically includes the following steps:

[0124] The first step is to prepare a sodium silicate aqueous solution: add 175g of sodium silicate to a clean 500mL volumetric flask, then add deionized water to the scale line, and sonicate the solution in an ultrasonic instrument for 60 minutes to fully mix the deionized water and sodium silicate to obtain a 0.35g / mL sodium silicate aqueous solution.

[0125] The second step is to prepare the hydrochloric acid solution: add 20.83 mL of concentrated hydrochloric acid to a clean 100 mL volumetric flask, then add deionized water to the scale line, and ultrasonicate the solution for 30 minutes to fully mix the deionized water and hydrochloric acid to obtain a hydrochloric acid solution with a concentration of 2.5 mol / L.

[0126] The third step is to take 20 mL of sodium silicate aqueous solution into a clean beaker, add 10 mL of hydrochloric acid solution, stir evenly to control the pH of the mixed solution to about 7, let it stand until the silica is wet gelled, take out the wet gel, place it in a 1000 mL beaker, add 1000 mL of deionized water to replace the solution in the wet gel, let it stand for 48 hours, take out the wet gel, age it at 70 ° C for 24 hours to obtain a gel, and then freeze the gel for 24 hours. After freezing, put it into a vacuum freeze dryer and freeze-dry it at -70 ° C for 48 hours to obtain 4.88 g of pure silica aerogel.

[0127] Application Comparative Examples 1-3

[0128] Reference coating sample preparation method:

[0129] First, weigh 0.3-1 g of pure silica aerogel, 0.03-0.15 g of nano-ferric oxide, 0.03-0.15 g of nano-titanium dioxide, 0.2-1.0 mL of a 2 mg / mL graphene oxide aqueous solution, 15 g of titanium dioxide, and 3 g of diatomaceous earth in Comparative Example 1, pour them into a three-necked flask in sequence, add 10 mL of deionized water, then turn on the stirrer, stir for 20 minutes, add 4 mL of defoaming agent n-butanol and 4 mL of film-forming aid ethylene glycol, add 38 mL of water-based epoxy resin after high-speed stirring for 30 minutes, stir at low speed for 120 minutes, and then pour out to obtain a reference coating sample containing silica aerogel. The specific preparation parameters can be seen in Table 2 below:

[0130] Table 2

[0131]

[0132] Note: In Table 2, the numerical value before the sample name represents the total mass of silica aerogel, nano-ferric oxide, nano-titanium dioxide and graphene oxide added to the reference coating sample. The mass of each silica aerogel, nano-ferric oxide, nano-titanium dioxide and graphene oxide added to each comparative example is obtained by multiplying the mass percentage of each component in the composite silica aerogel obtained in Example 1 by the total mass of the four components added to the coating. The amount of silica aerogel contained in the composite silica aerogel in Example 1 is calculated based on the amount of 4.88 g of pure silica aerogel prepared from 20 mL of 0.35 g / mL sodium silicate aqueous solution in Comparative Example 1.

[0133] Testing and Analysis

[0134] The coatings obtained in Examples 1-4 and Comparative Examples 1-3 were subjected to the following tests 1-5, and the coatings obtained in Examples 5-7 were subjected to the following tests 2 and 4:

[0135] 1. Infrared test: At room temperature, a Thermo Nicolet Nexus 470 Fourier transform infrared spectrometer was used at a wave number of 4000-400 cm -1 The test was performed using total reflection infrared.

[0136] 2. Thermal insulation performance test: The specific method includes: (1) making two homemade thermal insulation boxes with temperature display and a 7*15cm tinplate-sized hole on the top of the thermal insulation box; (2) placing a 7*15cm blank tinplate (blank sample) and a tinplate coated with 6mm thick paint (paint sample) in the holes of the thermal insulation box and sealing them; (3) irradiating with a 350W infrared lamp, recording the temperature of the blank sample and the paint sample every 5 minutes, stopping the infrared lamp irradiation after 1 hour, and calculating the reference temperature. Reference temperature calculation method: subtract the temperature of the paint sample from the temperature of the blank sample to obtain the temperature difference.

[0137] 3. Emissivity test: Emissivity is based on infrared, and 1250-770cm is selected. -1 The wave number range is converted to a wavelength range of 8-13 μm, where the wavelength is equal to 10000 / wave number, and the transmittance is the emissivity.

[0138] 4. Adhesion test: Conducted in accordance with GB / T 5210-2006 "Paints and varnishes - Adhesion test by pull-off method".

[0139] 5. Hardness test: carried out in accordance with GB / T 6739-1996 "Determination of coating hardness by pencil method".

[0140] The test results and analysis are as follows:

[0141] The infrared test results of 0.4TIS-WER, 0.8TIS-WER, 1.2TIS-WER and 1.6TIS-WER and 0.4 reference, 0.8 reference and 1.2 reference are shown in the following table: Figure 2 As can be seen from the infrared diagram, the peak at 2950cm -1 is attributed to the -CH2 stretching vibration peak in the epoxy resin, the peak at 1650cm -1 is attributed to the characteristic peak of the benzene ring in the epoxy resin, the peak at 903cm -1 is attributed to the characteristic peak of the epoxy group in the epoxy resin, the peak at 1103cm -1 is attributed to the characteristic peak of Si-O-Si in the silica, and thus it can be seen that the coating containing composite silica aerogel + waterborne epoxy resin is successfully synthesized.

[0142] The heat insulation temperature difference performance test results of 0.4TIS-WER, 0.8TIS-WER, 1.2TIS-WER and 1.6TIS-WER and 0.4 reference, 0.8 reference and 1.2 reference after 60min are shown in the following table: Figure 3 As can be seen from the diagram, the heat insulation performance of the coating is improved by increasing the composite silica aerogel in the component, the heat insulation performance of the coating containing 0.4-1.6g of the composite silica aerogel is improved, and the heat insulation performance of the coating sample is better than that of the 0.4 reference, 0.8 reference and 1.2 reference of the coating directly added with silica aerogel, nano ferric oxide, nano titanium dioxide and graphene oxide, wherein the temperature difference of the 1.2 reference is close to that of 0.4TIS-WER, and the temperature difference of the 0.4 reference and 0.8 reference is lower than that of 0.4TIS-WER, indicating that the composite silica aerogel prepared by the present application is more conducive to improving the heat insulation performance. Especially the 1.2TIS-WER, the reference temperature difference can always be kept at about 3℃ during the continuous test time, and the heat insulation effect is the most ideal.

[0143] The heat insulation temperature difference performance test results of the coatings of application example 3 (1.2TIS-WER), application examples 5-7 are shown in the following table: Figure 4 As can be seen from the diagram, the 1.2TIS-WER can achieve the best heat insulation effect more quickly and the heat insulation effect is always the best during the whole test process, although the application example 6 can also achieve a similar heat insulation effect to that of the 1.2TIS-WER after a period of time, but the time to achieve the best heat insulation effect is slower than that of the 1.2TIS-WER, and the application examples 5 and 7 take a long time to achieve the best heat insulation effect, and the best heat insulation effect of the coatings of the two application examples is slightly worse than that of the 1.2TIS-WER.

[0144] The emissivity test results of 0.4TIS-WER, 0.8TIS-WER, 1.2TIS-WER and 1.6TIS-WER and 0.4 reference, 0.8 reference and 1.2 reference are shown in Fig. 1. Figure 5 After being affected by solar radiation, the absorbed heat is converted into infrared radiation by the high infrared emissivity of nano-ferroferric oxide and emitted to the atmospheric window (8-13 μm) range, thereby realizing radiative cooling. The minimum emissivity values of the samples with composite silica aerogel added in the spectrum at 8-13 μm wavelengths are all higher than those of the coating samples of 0.4 reference, 0.8 reference and 1.2 reference with direct addition of silica aerogel, nano-ferroferric oxide, nano-titanium dioxide and graphene oxide. Among them, the minimum emissivity of 0.4 reference, 0.8 reference and 1.2 reference are all at 13 μm wavelength, all lower than 80%, while the minimum emissivity of the composite silica aerogel is 85.97% (0.8TIS-WER at 13 μm wavelength), and the maximum emissivity can reach 97.91% (1.6TIS-WER at 12.33 μm wavelength). Therefore, the composite silica aerogel prepared by the present application is more conducive to improving the emissivity and realizing radiative cooling.

[0145] The adhesion test results of 0.4TIS-WER, 0.8TIS-WER, 1.2TIS-WER and 1.6TIS-WER and 0.4 reference, 0.8 reference and 1.2 reference are shown in Fig. 2. Figure 6 As can be seen from the figure, the adhesion of 0.8TIS-WER and 1.2TIS-WER is better than that of 0.8 reference and 1.2 reference, the adhesion of 0.8 reference is 0.94 MPa, the adhesion of 1.2 reference is 0.71 MPa, while the adhesion of 0.8TIS-WER is 1.21 MPa and the adhesion of 1.2TIS-WER is 0.96 MPa. The adhesion of 0.4TIS-WER is not as good as that of 0.4 reference, which may be due to the direct addition of a small amount of silica aerogel, nano-ferroferric oxide, nano-titanium dioxide and graphene oxide, which improves the adhesion. And 0.8TIS-WER and 1.2TIS-WER, due to the addition of an appropriate amount of composite silica aerogel, can better adhere to the floor with the base material epoxy resin, thereby effectively increasing the adhesion of the coating.

[0146] The adhesion test results of the coatings of application example 3 (1.2TIS-WER), application examples 5-7 are shown in Fig. 3. Figure 7 As can be seen from the figure, when 1.2 g of composite silica aerogel is added to the coating, the adhesion of 1.2TIS-WER is the best, reaching 0.96 MPa, while the adhesion of application examples 5-7 decreases to 0.51 MPa, 0.6 MPa and 0.3 MPa respectively.

[0147] The pencil hardness test standards of 0.4TIS-WER, 0.8TIS-WER, 1.2TIS-WER and 1.6TIS-WER and 0.4 reference, 0.8 reference and 1.2 reference are shown in Table 3:

[0148] Table 3 Pencil hardness standard table of the coatings obtained from application examples 1-4 and comparative examples 1-3

[0149]

[0150] Hardness test standard: pencil numbers are 6H, 5H, 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, and 6B, with 6H being the hardest and 6B being the softest. The hardness decreases from 6H to 6B. According to GB / T6739-1996 "Coating Hardness Pencil Determination Method," the hardness of the coating reaches H, which meets the coating hardness standard. Hardness testing revealed that the coating with composite silica aerogel had a higher hardness, at or above HB, much higher than the 3B and 4B values ​​of the reference coating samples, compared to the 0.4, 0.8, and 1.2 reference coating samples to which silica aerogel, nano-ferric oxide, nano-titanium dioxide, and graphene oxide were directly added. This indicates that the composite silica aerogel prepared by the present invention can enhance coating hardness.

[0151] The thermal conductivity of 0.4TIS-WER, 0.8TIS-WER, 1.2TIS-WER and 1.6TIS-WER is as follows Figure 8 As shown, they are 0.166mm 2 / s、0.208mm 2 / s, 0.257mm 2 / s, 0.190mm 2 / s, compared with the existing coatings of this type (thermal conductivity 0.382mm 2 / s), the smaller the thermal conductivity, the better the thermal insulation performance.

[0152] The scanning electron microscope images of pure silica aerogel (a) scanned at 450 times and the scanning electron microscope images of composite silica aerogel (b) scanned at 450 times are shown in Figure 2. Figure 9 As shown in the figure, it can be found that in the composite silica aerogel prepared by the present invention, nano-iron oxide, nano-titanium dioxide and graphene oxide are tightly structured with silica and wrapped around silica.

[0153] The scanning electron micrographs of 0.4TIS-WER (a) at 450 times scanning, 0.8TIS-WER (b) at 450 times scanning, 1.2TIS-WER (c) at 450 times scanning, and 1.6TIS-WER (d) at 450 times scanning are shown in the figure. Figure 10As shown in the figure, it can be seen that the coating containing composite silica aerogel prepared by the present invention has a smooth surface, and the fine and uniform particles on the surface are composite silica aerogel, which can be evenly dispersed in the coating.

[0154] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. An aerogel coating, characterized in that: The invention comprises composite silica aerogel, titanium dioxide, diatomaceous earth, a defoamer, a film-forming aid, a water-based epoxy resin and water; based on the total mass of the aerogel coating being 100%, the composite silica aerogel comprises 0.5-2.5wt%, titanium dioxide 12-19wt%, diatomaceous earth 1-4wt%, a defoamer 5-12.5wt%, a film-forming aid 5-12.5wt%, a water-based epoxy resin 37.5-50wt% and water 12-25wt%. The preparation method of the composite silica aerogel comprises the following steps: S1, ultrasonically mixing the sodium silicate aqueous solution with the nano-ferric oxide, nano-titanium dioxide and graphene oxide aqueous solutions, and then adding the hydrochloric acid solution and stirring to control the pH of the obtained mixed solution to 4-9; S2, sequentially subjecting the mixed solution obtained in step S1 to wet gelation, solution replacement, aging, freezing, and drying to obtain a composite silica aerogel, forming a tight network structure in which the silica aerogel is filled with nano-ferric oxide, nano-titanium dioxide, and graphene oxide and composited with silica; In step S1, the mass ratio of sodium silicate in the sodium silicate aqueous solution to nano-ferric oxide, nano-titanium dioxide and graphene oxide in the graphene oxide aqueous solution is 6-10:0.4-1.2:0.4-1.2:0.005-0.

01.

2. The aerogel coating according to claim 1, wherein In the aerogel coating, the content of the composite silica aerogel is 1.1 to 1.3 wt%; In step S1, the mass ratio of sodium silicate in the sodium silicate aqueous solution to nano-ferric oxide, nano-titanium dioxide and graphene oxide in the graphene oxide aqueous solution is 6-8:0.7-0.8:0.7-0.8:0.009-0.

01.

3. The aerogel coating according to claim 1, wherein: In step S1, the pH of the mixed solution is 7-8.

4. The aerogel coating according to claim 1, wherein In step S1, the concentration of the sodium silicate aqueous solution is 0.3-0.6 g / mL; and / or, the concentration of the hydrochloric acid solution is 2.5 to 7.5 mol / L; And / or, the concentration of the graphene oxide aqueous solution is 0.5-2 mg / mL.

5. The aerogel coating according to claim 1, wherein In step S1, the sodium silicate aqueous solution is obtained by ultrasonically mixing sodium silicate and water for 30 to 60 minutes; And / or, the hydrochloric acid solution is obtained by ultrasonically mixing concentrated hydrochloric acid and water for 10 to 30 minutes; And / or, the time for ultrasonically mixing the sodium silicate aqueous solution with the nano-ferric oxide, nano-titanium dioxide and graphene oxide aqueous solutions is 10 to 30 minutes.

6. The aerogel coating according to claim 1, wherein: In step S2, the replacement solution is to replace the solution in the obtained wet gel with water; and / or, the replacement solution is allowed to stand for 24 to 48 hours; And / or, the aging temperature is 30-70°C; And / or, the aging time is 12 to 24 hours; And / or, the freezing time is 12 to 24 hours; And / or, the drying temperature is -70 to -85°C; And / or, the drying time is 48 to 50 hours.

7. The aerogel coating according to claim 1, wherein: The defoamer is one of n-butanol, silicone defoamer or polyether defoamer; And / or, the film-forming aid is one of ethylene glycol, propylene glycol butyl ether, dodecyl alcohol ester and hydrocarbons.

8. A method for preparing the aerogel coating according to any one of claims 1 to 7, characterized in that: include: First, titanium dioxide, composite silica aerogel and diatomaceous earth are added to a reaction container in sequence; then, water is added and stirred for a certain period of time, and then a defoaming agent and a film-forming aid are added; finally, water-based epoxy resin is added after stirring at high speed for a certain period of time, and the material is discharged after continuing to stir for a certain period of time, thereby preparing an aerogel coating containing the composite silica aerogel.

9. The preparation method according to claim 8, wherein The time for adding water and stirring is 5 to 20 minutes; and / or, the time for further high-speed stirring is 10 to 30 minutes; and / or, the time for continuing stirring is 120 to 240 minutes.

10. A coating, characterized in that The coating is formed by coating the aerogel coating according to any one of claims 1 to 7 or the aerogel coating prepared by the preparation method according to claim 8 or 9.

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