SiO2 aerogel composite material, composite plate containing same, and preparation and application thereof

Abstract

The present application discloses a SiO2 aerogel composite material, a composite board containing the same, and its preparation and application. The preparation of the SiO2 aerogel composite material includes the following steps: a silicon source, an organic solvent, water, and an acidic catalyst are subjected to a hydrolysis reaction, cooled to room temperature, the pH value is adjusted to 8-8.5, and a condensation reaction is performed to obtain a SiO2 sol; rock wool staple fibers are soaked in a hydroxyl-containing polar organic solvent, ultrasonicated, and dried to obtain activated rock wool staple fibers; 1 part of the SiO2 sol is mixed with 10-25 parts of the activated rock wool staple fibers, sealed and stored, subjected to heat aging and polar solvent aging, and then solvent replacement with a polar organic solvent and a non-polar organic solvent in sequence, surface hydrophobic modification, washing, and normal pressure drying to obtain a SiO2 aerogel composite material. The SiO2 aerogel composite material and composite board prepared in the present application have a low thermal conductivity, are not prone to cracking and chipping, have better mechanical properties, and are energy-saving, emission-reducing, and cost-reducing.

Description

Technical Field

[0001] The present application belongs to the field of construction technology, and in particular relates to a SiO2 aerogel composite material, a composite board containing the same, and preparation and application thereof. Background Art

[0002] Silica (SiO2) aerogels differ from dense porous systems in that they consist of a low-density network of SiO2 filaments with a porosity of up to 99.8%. The unique structure of SiO2 aerogels leads to their unusual properties, such as extremely low density, high porosity, low thermal conductivity, high optical transparency, low refractive index, low dielectric constant and a low temperature of 100 m·s -1 The unique properties of SiO2 aerogel make it suitable for applications in electrical, thermal, optical, chemical and other fields.

[0003] The excellent properties of SiO2 aerogel and the advancement of technology have enabled SiO2 aerogel to enter industrial production. In fact, due to the cheap silicon source, silicon aerogel is expected to have a wider range of applications, especially in super-thermal insulators. However, SiO2 aerogel still faces the problems of fragility and low strength. For example, when aerogel is used as an insulating material, its fragility limits its actual use and it cannot be used alone as an insulation board in the scene. The current process route for industrial SiO2 aerogel insulation boards is to mix aerogel powder with some additives to make a slurry, use a template to shape it, or go through a series of processing techniques to make aerogel insulation boards. Although this method is simple and easy to operate, the thermal insulation effect of the product is not ideal.

[0004] Therefore, there is an urgent need in this field to develop a SiO2 aerogel material that has ideal thermal insulation performance, excellent mechanical properties, and is not prone to cracking or chipping during use. Summary of the Invention

[0005] The technical problem addressed by this application is to overcome the shortcomings of the prior art by providing a SiO2 aerogel composite material, a composite board containing the same, and its preparation and application. The SiO2 aerogel composite material and SiO2 aerogel composite board produced in this application preserve the pore structure of the SiO2 aerogel, exhibit low thermal conductivity, are less susceptible to cracking and chipping, and exhibit superior mechanical properties. The use of atmospheric pressure drying technology achieves energy conservation and emission reduction, reduces costs, and is safe and reliable. The composite material is suitable for industrial production and can be applied in various architectural scenarios.

[0006] This application adopts the following technical solutions to solve the above technical problems:

[0007] The present application provides a method for preparing a SiO2 aerogel composite material, which comprises the following steps:

[0008] (a1) a silicon source, an organic solvent, water, and an acidic catalyst are subjected to a hydrolysis reaction, cooled to room temperature, the pH value of the system is adjusted to 8 to 8.5, and subjected to a polycondensation reaction to obtain a SiO2 sol;

[0009] (a2) soaking the rock wool staple fibers in a hydroxyl-containing polar organic solvent, ultrasonically treating the fibers, and drying the fibers to obtain activated rock wool staple fibers;

[0010] (a3) uniformly mixing the SiO2 sol obtained in step (a1) and the activated rock wool short fibers obtained in step (a2), sealing and storing, sequentially subjecting the mixture to heat aging and polar solvent aging, then sequentially subjecting the mixture to solvent replacement with a polar organic solvent and a non-polar organic solvent, surface hydrophobic modification, washing, and normal pressure drying to obtain a SiO2 aerogel composite material; the mass ratio of the SiO2 sol to the activated rock wool short fibers is (10-25):1;

[0011] There is no particular order in which step (a1) and step (a2) are performed.

[0012] In step (a1), the silicon source may include at least one of tetraethyl orthosilicate, methyltriethoxysilane, and methyltrimethoxysilane, preferably tetraethyl orthosilicate. During research and development, it was found that using tetraethyl orthosilicate as the silicon source resulted in the best thermal insulation performance for the SiO2 aerogel composite, and this insulation performance can be maintained stably over the long term.

[0013] In step (a1), the organic solvent may include an alcohol organic solvent and / or an alkane organic solvent, preferably includes ethanol and / or n-hexane.

[0014] In step (a1), the acidic catalyst may include at least one of hydrochloric acid, nitric acid, sulfuric acid and hydrofluoric acid, preferably hydrochloric acid.

[0015] In step (a1), the molar ratio of the silicon source, the organic solvent, the water and the acidic catalyst may be 1: (2-10): (5-25): (10 -4 ~10 -2 ), preferably 1:5:10:10 -3 .

[0016] In step (a1), the temperature of the hydrolysis reaction can be 70-100°C, preferably 80-90°C.

[0017] In step (a1), the hydrolysis reaction time can be 2.5 to 5.5 hours, preferably 3 to 4 hours.

[0018] In step (a1), preferably, the pH value of the system is adjusted to 8.3.

[0019] In step (a1), the method for adjusting the pH value of the system to 8-8.5 can be conventional in the art, and generally a basic catalyst is added.

[0020] Wherein, the alkaline catalyst may include aqueous ammonia.

[0021] The alkaline catalyst can be added dropwise according to conventional methods in the art.

[0022] In step (a1), the polycondensation reaction can be carried out under stirring conditions according to the conventional art, and the stirring speed can be 1000-1400 rpm.

[0023] In step (a1), the polycondensation reaction time may be 20 to 40 minutes, preferably 25 to 30 minutes.

[0024] In step (a1), the temperature of the polycondensation reaction may be room temperature.

[0025] In step (a2), the length of the rock wool short fibers may be 5 to 30 mm, preferably 10 to 20 mm, for example 13 mm.

[0026] In step (a2), the diameter of the rock wool short fibers may be 5 to 15 μm, for example, 12 μm.

[0027] In step (a2), the hydroxyl-containing polar organic solvent may include an alcohol solvent, preferably anhydrous ethanol.

[0028] In step (a2), the mass ratio of the rock wool short fibers to the hydroxyl-containing polar organic solvent may be 1:(20-100), preferably 1:50.

[0029] In step (a2), the soaking temperature may be room temperature.

[0030] In step (a2), the soaking time may be 20 to 60 minutes.

[0031] In step (a2), the frequency of the ultrasound can be a frequency that can be achieved by ultrasound instruments in the art, preferably 20 to 40 kHz.

[0032] In step (a2), the ultrasonication time may be 15 to 45 minutes.

[0033] In step (a2), the drying method may be normal pressure drying.

[0034] In step (a2), the drying temperature may be 100-120°C.

[0035] In step (a2), the drying time may be 3 to 4 hours.

[0036] In step (a3), the mass ratio of the SiO2 sol to the activated rock wool short fibers is preferably (10-20):1, more preferably (14-18):1.

[0037] In step (a3), a reinforcing agent and / or a dispersing agent may be added during the mixing process.

[0038] The reinforcing agent may include N,N-dimethylformamide. During the research and development process, it was found that the addition of the reinforcing agent can increase the strength of the aerogel skeleton and offset some of the pore collapse caused by the drying process.

[0039] The mass ratio of the SiO2 sol to the reinforcing agent may be 1:(0.01-0.1), preferably 1:0.025.

[0040] The dispersant may include at least one of sodium pyrophosphate, sodium hexametaphosphate, sodium polyacrylate, stearamide, cellulose and polyethylene glycol, preferably polyethylene glycol.

[0041] Wherein, the mass ratio of the SiO2 sol to the dispersant can be 1:(10 -3 ~5×10 -3 ), preferably 1:4.5×10 -3 .

[0042] In step (a3), the sealed storage time can be 10 to 36 hours, preferably 24 to 28 hours.

[0043] In step (a3), the sealed storage temperature can be 50-70°C, preferably 60°C.

[0044] In step (a3), it was found during the research and development process that when heat aging and polar solvent aging are used simultaneously, the strength of the SiO2 aerogel network skeleton can be effectively enhanced, and the volume shrinkage of the system during the drying process can be reduced to prevent pore collapse and the degradation of thermal insulation performance.

[0045] In step (a3), the heat aging can be performed in an oven according to conventional techniques in the art.

[0046] In step (a3), the heat aging temperature may be 50-65°C, preferably 60-65°C.

[0047] In step (a3), the heat aging time may be 24 to 50 hours, preferably 36 to 48 hours.

[0048] In step (a3), the polar solvent used in the polar solvent aging may include water and / or alcohol solvents, preferably water and ethanol.

[0049] When the polar solvent includes the water and the alcohol solvent, the volume ratio of the water to the alcohol solvent may be 1:(3-5), preferably 1:4.

[0050] In step (a3), the aging time of the polar solvent can be 12 to 20 hours, preferably 16 hours.

[0051] Wherein, the aging temperature of the polar solvent may be room temperature.

[0052] In step (a3), when the polar organic solvent is used for the solvent replacement, the polar organic solvent can be a conventional polar organic solvent used in the art that does not chemically react with other materials in the system, preferably an alcohol solvent, more preferably anhydrous ethanol. The purpose of using the polar organic solvent for the solvent replacement is to remove unreacted silicon source, water, and alkaline catalyst in the system.

[0053] In step (a3), when the polar organic solvent is used for the solvent replacement, the solvent replacement time can be 8 to 12 hours, preferably 10 hours.

[0054] In step (a3), when the polar organic solvent is used for the solvent replacement, the temperature of the solvent replacement can be 50-65°C, preferably 60°C.

[0055] In step (a3), when the solvent replacement is performed using the non-polar organic solvent, the non-polar organic solvent can be a non-polar organic solvent commonly used in the art that does not chemically react with other materials in the system, preferably including an alkane solvent, more preferably including n-hexane, such as n-hexane with a purity of 99.9%. The purpose of using the non-polar organic solvent for the solvent replacement is to utilize the lower surface tension of the non-polar organic solvent to further increase the skeleton strength of the wet gel, reduce the pore collapse caused by subsequent atmospheric pressure drying, and prepare for the next step of surface hydrophobic modification.

[0056] In step (a3), when the non-polar organic solvent is used for the solvent replacement, the solvent replacement time may be 6 to 10 hours.

[0057] In step (a3), when the non-polar organic solvent is used for the solvent replacement, the temperature of the solvent replacement can be 40-50°C.

[0058] In step (a3), the surface hydrophobic modification method may include the following steps: completely immersing the solvent-displaced material in a modifier containing trimethylsilyl groups and a non-polar organic solvent, and allowing the mixture to react. The purpose of the surface hydrophobic modification is primarily to replace the more polar hydroxyl groups (-OH) on the surface of the material with trimethylsilyl groups (CH3)3Si-, which have low polarity. This effectively prevents pore collapse caused by volume shrinkage during drying of the SiO2 aerogel composite material, and the product becomes hydrophobic, which helps maintain the product's good thermal insulation and waterproof properties.

[0059] During the surface hydrophobic modification process, the modifier containing a trimethylsilyl group may include trimethylchlorosilane.

[0060] During the surface hydrophobic modification process, the non-polar organic solvent may include an alkane solvent, preferably n-hexane, for example, n-hexane with a purity of 99.9% or more.

[0061] During the surface hydrophobic modification process, the volume ratio of the modifier containing trimethylsilyl groups to the non-polar organic solvent may be 1:(8-10), preferably 1:9.

[0062] In step (a3), the surface hydrophobic modification time can be 2 to 4 days, preferably 3 days.

[0063] In step (a3), the temperature for the surface hydrophobic modification may be 30-45°C, preferably 40°C.

[0064] In step (a3), the washing method comprises the following steps: immersing the surface-hydrophobically modified material in a non-polar organic solvent for washing. The purpose of the washing is to remove unreacted trimethylsilyl group-containing modifying solution, further completely displace water and other solvents in the system, reduce capillary forces, and prepare for the next step of normal pressure drying.

[0065] The non-polar organic solvent may include an alkane solvent, preferably n-hexane, for example, n-hexane with a purity of 99.9% or more.

[0066] In step (a3), the washing time may be 10 to 12 hours.

[0067] In step (a3), the washing temperature may be 40-50°C.

[0068] In step (a3), the conditions and methods for drying at normal pressure can be conventional in the art, preferably a normal pressure graded drying method, more preferably drying at 55-65°C, 75-85°C, 95-105°C, 115-125°C and 155-165°C in sequence, with each stage drying time being 2-5h, for example, drying at 60°C, 80°C, 100°C, 120°C and 160°C in sequence, with each stage drying time being 2h. When the normal pressure graded drying method is adopted, the solvent can be effectively prevented from volatilizing too quickly, causing pore collapse and cracking of the product. The normal pressure graded drying method can promote the orderliness of the entire drying degree, be safe and controllable, and ensure good product quality.

[0069] Existing technologies often use supercritical drying for drying. However, the supercritical drying process requires relatively long experimental cycles, low yields, high costs, and very demanding equipment, making it difficult to industrialize. Using atmospheric pressure drying can lead to problems such as poor performance of the resulting insulation board, prone to cracking and chipping, and poor mechanical properties. The inventors of this application creatively added activated rock wool staple fibers to the silica aerogel preparation process, and combined this with a two-step aging and two-step solvent replacement method to cleverly address the aforementioned issues with atmospheric pressure drying.

[0070] The present application provides a SiO2 aerogel composite material, which is prepared by the above-mentioned preparation method of the SiO2 aerogel composite material.

[0071] The present application also provides an application of the SiO2 aerogel composite material as described above as a thermal insulation material in the construction field.

[0072] The present application provides a method for preparing a SiO2 aerogel composite plate, which comprises the following steps:

[0073] Step (b1) is the same as step (a1) in the method for preparing the SiO2 aerogel composite material as described above, to obtain the SiO2 sol;

[0074] Step (b2) is the same as step (a2) in the method for preparing the SiO2 aerogel composite material as described above, to obtain the activated rock wool short fibers;

[0075] Step (b3): uniformly mixing the SiO2 sol prepared in step (b1) and the activated rock wool short fibers prepared in step (b2), injecting the mixture into a grid, sealing and storing the mixture, sequentially subjecting the mixture to heat aging and polar solvent aging, and then sequentially subjecting the mixture to solvent replacement with a polar organic solvent and a non-polar organic solvent, surface hydrophobic modification, washing, and normal pressure drying to obtain a SiO2 aerogel composite board; the mass ratio of the SiO2 sol to the activated rock wool short fibers is (10-25):1;

[0076] There is no particular order in which step (b1) and step (b2) are performed.

[0077] In step (b3), the conditions and methods for the mixing, the sealed storage, the heat aging, the polar solvent aging, the solvent replacement, the surface hydrophobic modification, the washing or the normal pressure drying are the same as the conditions and methods for the corresponding operations in step (a3) of the preparation method of the SiO2 aerogel composite material as described above.

[0078] In step (b3), the grid may comprise a three-dimensional grid. In the SiO2 aerogel composite plate produced in this application, the SiO2 aerogel composite material has a strong bond with the grid, making it difficult for the SiO2 aerogel to fall off the grid. Furthermore, the grid further enhances the mechanical strength of the SiO2 aerogel composite plate.

[0079] In which, the three-dimensional grid includes at least two mesh layers and a connecting layer arranged between two adjacent mesh layers. The mesh layer includes multiple groups of first and second woven wires interwoven with each other. The connecting layer includes a third woven wire, and the third woven wire is connected to the two adjacent mesh layers.

[0080] Preferably, the first filament, the second filament and the third filament have different extension directions; with x, y and z as the three axes of the three-dimensional rectangular coordinate system, the first filament is the x-direction filament, the second filament is the y-direction filament, and the third filament is the z-direction filament.

[0081] Preferably, the grid layer is planar or curved.

[0082] Preferably, the third woven yarn is arranged in an "X" shape between the two mesh layers.

[0083] Preferably, the "X"-shaped third filaments are connected at their own intersection points.

[0084] In step (b3), the material of the grid may include at least one of glass fiber, carbon fiber and basalt fiber.

[0085] In step (b3), the three-dimensional grid may be a multi-layer three-dimensional grid core woven fabric disclosed in Chinese patent ZL201410041645.X.

[0086] In step (b3), after the normal pressure drying operation, resin may be coated on the surface of the obtained material.

[0087] The resin may include a radiation-proof resin commonly used in the art. The radiation-proof resin may be a commonly used resin for shielding neutrons and subneutrons, preferably comprising at least one of an organosilicon-modified boron phenolic resin, a xylene-modified boron phenolic resin, and a diphenyl ether formaldehyde resin. The radiation-proof resin may improve the insulation, radiation resistance, and water resistance of the SiO2 aerogel composite panel.

[0088] In a more preferred embodiment, the resin coating step may further include coating the resin surface with a fiber cloth. The resin coating, such as the radiation-proof resin, not only ensures the SiO2 aerogel composite board has radiation-proof properties, but also effectively bonds the fiber cloth to the SiO2 aerogel.

[0089] The fiber cloth may include at least one of glass fiber cloth, polyester fiber cloth and carbon fiber cloth, preferably carbon fiber cloth.

[0090] In a further preferred embodiment, resin is coated on the surface of the fiber cloth.

[0091] The resin may be selected from at least one of the resins mentioned above.

[0092] The present application provides a SiO2 aerogel composite plate, which is prepared by the above-mentioned preparation method of the SiO2 aerogel composite plate.

[0093] The present application also provides an application of the SiO2 aerogel composite board as described above as a thermal insulation material in the construction field.

[0094] In some embodiments, when the radiation-proof resin is coated during the preparation of the SiO2 aerogel composite board, the SiO2 aerogel composite board can be used as a radiation-proof heat-insulating material in the construction field.

[0095] In this application, room temperature generally refers to 20-35°C.

[0096] On the basis of conforming to the common sense in this field, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present application.

[0097] The reagents and raw materials used in this application are commercially available.

[0098] The positive progress of this application is that it improves the preparation process of SiO2 aerogel, adds activated rock wool short fibers during the preparation of SiO2 aerogel composite materials, and combines a two-step aging method, a two-step solvent replacement method, and a normal pressure drying method. This method promotes the prepared SiO2 aerogel composite material to have a lower thermal conductivity coefficient, while also effectively solving the problems of SiO2 aerogel being prone to cracking and falling apart, and the mechanical properties of the prepared SiO2 aerogel composite material are superior. The use of normal pressure drying technology achieves energy conservation and emission reduction, reduces costs, is safe and reliable, is suitable for industrial production, and can meet the application needs of various architectural scenarios.

[0099] In the process of preparing SiO2 aerogel composite panels in this application, the grid is used as a carrier, which greatly enhances the mechanical properties of the SiO2 aerogel composite panels. The prepared SiO2 aerogel composite panels are not easy to crack or chip, and the pore structure of the SiO2 aerogel is protected, maintaining good thermal insulation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0100] The present disclosure may be better understood by referring to the following description in conjunction with the accompanying drawings, which together with the following detailed description are incorporated in and form a part of this specification and are used to further illustrate the preferred embodiments of the present disclosure and to explain the principles and advantages of the present disclosure.

[0101] in:

[0102] Figure 1 Schematic diagram of the preparation steps of the SiO2 aerogel composite material in Example 1;

[0103] Figure 2 Schematic diagram of the preparation steps of the SiO2 aerogel composite plate in Example 2;

[0104] Figure 3 This is a front view of the structure of the three-dimensional grid in Example 2;

[0105] Figure 4 This is a schematic diagram of the partial three-dimensional structure of the three-dimensional grid in Example 2.

[0106] Description of Figure Numbers:

[0107] 100 - mesh layer, 110 - first woven wire, 120 - second woven wire, 200 - connection layer, 210 - third woven wire. DETAILED DESCRIPTION

[0108] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. In the following examples, the experimental methods without specific conditions are selected according to conventional methods and conditions or according to the product specifications.

[0109] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0110] It should be noted that if there are directional indications (such as up, down, left, right, front, back, etc.) in this application, such directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0111] Example 1

[0112] Preparation method of SiO2 aerogel composite material, preparation steps are as follows Figure 1 As shown, the following steps are included:

[0113] (1) Mix ethyl orthosilicate, ethanol, water and hydrochloric acid in the ratio of 1:5:10:10. -3 The mixture was stirred at a molar ratio of 1:1 and 1:2, and hydrolyzed at 90° C. for 4 h. After the reaction, the mixture was cooled to 25° C., and an alkaline catalyst (ammonia water) was added dropwise to the system to adjust the pH value of the system to 8.3. The polycondensation reaction was carried out at room temperature and a stirring speed of 1000 rpm for 30 min to obtain SiO2 sol.

[0114] (2) At room temperature, rock wool short fibers with a length of 13 mm and a diameter of 12 μm were soaked in anhydrous ethanol for 20 min, with the mass ratio of rock wool short fibers to anhydrous ethanol being 1:50; then ultrasonic treatment was performed, with the ultrasonic frequency being 40 kHz and the ultrasonic time being 15 min. After ultrasonication, the material was transferred to an oven and dried at normal pressure at a temperature of 120 ° C for 4 h to obtain activated rock wool short fibers;

[0115] (3) The SiO2 sol prepared in step (1), the activated rock wool short fiber prepared in step (2), the reinforcing agent (N,N-dimethylformamide) and the dispersant (polyethylene glycol) were mixed in a ratio of 1:0.07:0.025:4.5×10 -3The mass ratio of the raw materials was evenly mixed, and then sealed and stored at 60 ° C for 24 hours; the sealed and stored materials were transferred to a 60 ° C oven for heat aging for 48 hours; at room temperature, the heat-aged materials were immersed in a mixture of water and ethanol (the volume ratio of water to ethanol was 1:4) for polar solvent aging for 16 hours; the polar solvent-aged materials were first immersed in 60 ° C anhydrous ethanol for solvent replacement for 10 hours, and then immersed in 50 ° C 99.9% pure n-hexane for solvent replacement for 6 hours; after solvent replacement, The material was completely immersed in a mixed solution of trimethylchlorosilane and n-hexane for modification, wherein the volume ratio of trimethylchlorosilane to n-hexane was 1:9, the modification time was 3 days, and the modification temperature was 40°C; then it was washed with n-hexane with a purity of 99.9% at 50°C for 12 hours; the washed material was dried at temperatures of 60°C, 80°C, 100°C, 120°C, and 160°C, respectively, with the drying time for each stage being 2 hours, to obtain a SiO2 aerogel composite material.

[0116] Example 2

[0117] The preparation method of SiO2 aerogel composite board includes the following steps: Figure 2 As shown, the following steps are included:

[0118] (1) Mix ethyl orthosilicate, ethanol, water and hydrochloric acid in the ratio of 1:5:10:10. -3 The mixture was stirred at a molar ratio of 1:1 and 1:2, and hydrolyzed at 90° C. for 4 h. After the reaction, the mixture was cooled to 25° C., and an alkaline catalyst (ammonia water) was added dropwise to the system to adjust the pH value of the system to 8.3. The polycondensation reaction was carried out at room temperature and a stirring speed of 1000 rpm for 30 min to obtain SiO2 sol.

[0119] (2) At room temperature, rock wool short fibers with a length of 13 mm and a diameter of 12 μm were soaked in anhydrous ethanol for 20 min, with the mass ratio of rock wool short fibers to anhydrous ethanol being 1:50; then ultrasonic treatment was performed, with the ultrasonic frequency being 40 kHz and the ultrasonic time being 15 min. After ultrasonication, the material was transferred to an oven and dried at a temperature of 120 ° C for 4 h to obtain activated rock wool short fibers;

[0120] (3) The SiO2 sol prepared in step (1), the activated rock wool short fiber prepared in step (2), the reinforcing agent (N,N-dimethylformamide) and the dispersant (polyethylene glycol) were mixed in a ratio of 1:0.07:0.025:4.5×10 -3The mixture was uniformly mixed in a mass ratio of 1:1 and injected into a three-dimensional grid of glass fiber, and then sealed and stored at 60°C for 24 hours; the sealed and stored material was transferred to a 60°C oven for heat aging for 48 hours; at room temperature, the heat-aged material was immersed in a mixture of water and ethanol (the volume ratio of water to ethanol was 1:4) for polar solvent aging for 16 hours; the polar solvent-aged material was first immersed in 60°C anhydrous ethanol for solvent replacement for 10 hours, and then immersed in 50°C 99.9% pure n-hexane for solvent replacement 6h; the material after solvent replacement is completely immersed in a mixed solution of trimethylchlorosilane and n-hexane for modification, the volume ratio of trimethylchlorosilane and n-hexane is 1:9, the modification time is 3 days, and the modification temperature is 40°C; then it is washed with n-hexane with a purity of 99.9% at 50°C for 12h; the washed material is dried at temperatures of 60°C, 80°C, 100°C, 120°C, and 160°C, respectively, and the drying time for each stage is 2h to obtain a SiO2 aerogel composite plate.

[0121] In this embodiment, the three-dimensional fiberglass grid is as follows Figure 3 As shown, the three-dimensional grid includes five mesh layers 100 and four connecting layers 200. The mesh layers 100 and the connecting layers 200 are both woven from woven silk. In this embodiment, the woven silk is made of stranded glass fiber. In other embodiments, one or more strands of glass fiber, carbon fiber, or basalt fiber can also be selected. In addition, it should be noted that in this embodiment, five mesh layers 100 and four connecting layers 200 are provided, but in other embodiments, more or fewer mesh layers 100 and connecting layers 200 can be provided. The specific number of mesh layers 100 and connecting layers 200 can be determined according to the thickness of the SiO2 aerogel composite board.

[0122] Continue to refer to Figure 4 Taking two mesh layers 100 and one connecting layer 200 as an example, the upper and lower mesh layers 100 have the same structure and respectively constitute the top and bottom layers of the glass fiber three-dimensional grid. The mesh layer 100 includes a first woven wire 110 and a second woven wire 120. The first woven wire 110 and the second woven wire 120 are cross-woven to form a grid shape.

[0123] Continue to refer to Figure 4 The connecting layer 200 is located between the upper and lower mesh layers 100. The connecting layer 200 is composed of a third woven wire 210. The components of the third woven wire 210 can refer to the composition of the first woven wire 110 and the second woven wire 120 of the mesh layer 100, which will not be repeated here.

[0124] In this embodiment, the first, second, and third filaments extend in different directions; with x, y, and z as the three axes of a three-dimensional rectangular coordinate system, the first filament is an x-direction filament, the second filament is a y-direction filament, and the third filament is a z-direction filament. The first filament 110 and the second filament 120 are cross-woven in the horizontal directions (x and y directions) to form a grid, which can be a square grid, a rhombus, or a parallelogram grid; the third filament 130 is connected to the two adjacent grid layers 100 in the vertical direction (z direction).

[0125] In this embodiment, the third woven yarn 210 is connected to the two adjacent mesh layers 100 by a common weaving method. Figure 4 As shown, the third silk S1 starts from the intersection a of the first silk 110 and the second silk 120 of the bottom mesh layer 100, and is first woven together with the bottom mesh layer 100, and then extends upward to the intersection b of the top mesh layer 100, and is woven together with the top mesh layer 100, and then extends downward to the intersection c of the bottom mesh layer 100, and is woven together with the bottom mesh layer 100, and then extends upward to the intersection d of the top mesh layer 100, and is woven together with the top mesh layer 100, and so on. The third silk S1 is also woven together with the bottom mesh layer 100 at intersections e and g, and is woven together with the top mesh layer 100 at intersections f and h. Among them, after the weaving at intersection h is completed, you can also choose to continue weaving in the direction of intersection j, and of course you can also choose to continue weaving in the direction of intersection i. The embodiment of the present application does not limit the order of weaving. Similarly, the weaving method of the third silk S2 is the same as that of the third silk S1, and will not be repeated here. In addition, it should be noted that in Figure 4 In the embodiment, the third yarn 210 is not only woven in the horizontal direction, but also in the vertical direction. For example, the intersections a, b, c, d, e, and f are woven in the horizontal direction, while the intersections f, g, h, and i are woven in the vertical direction. Figure 4 Only the third woven wires 210 of the outermost layer on the front and the outer layer on the right are shown, and other areas are not shown. However, in actual weaving, each intersection of two adjacent mesh layers 100 is woven with third woven wires 210 in both horizontal and vertical directions.

[0126] from Figure 4 It is not difficult to see that in this embodiment, the third woven wire 210 extends upward from an intersection point of the lower layer of mesh to another intersection point of the adjacent upper layer of mesh 100, and then downward to another intersection point of the lower layer of mesh 100. After weaving in this way, when the third woven wire 210 is completely woven, an "X"-shaped connecting layer 200 is formed, so that the three-dimensional grid can maintain good stability no matter from which direction the force is applied.

[0127] Example 3

[0128] The preparation method of the SiO2 aerogel composite material is different from that of Example 1, except that in step (3), the mass ratio of the SiO2 sol to the activated rock wool short fiber is different and adjusted to 1:0.04. The other conditions and parameters are the same as those of Example 1, and the method includes the following steps:

[0129] (1) Mix ethyl orthosilicate, ethanol, water and hydrochloric acid in the ratio of 1:5:10:10. -3 The mixture was stirred at a molar ratio of 1:1 and 1:2, and hydrolyzed at 90° C. for 4 h. After the reaction, the mixture was cooled to 25° C., and an alkaline catalyst (ammonia water) was added dropwise to the system to adjust the pH value of the system to 8.3. The polycondensation reaction was carried out at room temperature and a stirring speed of 1000 rpm for 30 min to obtain SiO2 sol.

[0130] (2) At room temperature, rock wool short fibers with a length of 13 mm and a diameter of 12 μm were soaked in anhydrous ethanol for 20 min, with the mass ratio of rock wool short fibers to anhydrous ethanol being 1:50; then ultrasonic treatment was performed, with the ultrasonic frequency being 40 kHz and the ultrasonic time being 15 min. After ultrasonication, the material was transferred to an oven and dried at a temperature of 120 ° C for 4 h to obtain activated rock wool short fibers;

[0131] (3) The SiO2 sol prepared in step (1), the activated rock wool short fiber prepared in step (2), the reinforcing agent (N,N-dimethylformamide) and the dispersant (polyethylene glycol) were mixed in a ratio of 1:0.04:0.025:4.5×10 -3 The mass ratio of the raw materials was evenly mixed, and then sealed and stored at 60 ° C for 24 hours; the sealed and stored materials were transferred to a 60 ° C oven for heat aging for 48 hours; at room temperature, the heat-aged materials were immersed in a mixture of water and ethanol (the volume ratio of water to ethanol was 1:4) for polar solvent aging for 16 hours; the polar solvent-aged materials were first immersed in 60 ° C anhydrous ethanol for solvent replacement for 10 hours, and then immersed in 50 ° C 99.9% pure n-hexane for solvent replacement for 6 hours; after solvent replacement, The material was completely immersed in a mixed solution of trimethylchlorosilane and n-hexane for modification, wherein the volume ratio of trimethylchlorosilane to n-hexane was 1:9, the modification time was 3 days, and the modification temperature was 40°C; then it was washed with n-hexane with a purity of 99.9% at 50°C for 12 hours; the washed material was dried at temperatures of 60°C, 80°C, 100°C, 120°C, and 160°C, respectively, with the drying time for each stage being 2 hours, to obtain a SiO2 aerogel composite material.

[0132] Example 4

[0133] The preparation method of the SiO2 aerogel composite material is different from that of Example 1, except that in step (3), the mass ratio of the SiO2 sol to the activated rock wool short fiber is adjusted to 1:0.056. The other conditions and parameters are the same as those of Example 1, and the method includes the following steps:

[0134] (1) Mix ethyl orthosilicate, ethanol, water and hydrochloric acid in the ratio of 1:5:10:10. -3 The mixture was stirred at a molar ratio of 1:1 and 1:2, and hydrolyzed at 90° C. for 4 h. After the reaction, the mixture was cooled to 25° C., and an alkaline catalyst (ammonia water) was added dropwise to the system to adjust the pH value of the system to 8.3. The polycondensation reaction was carried out at room temperature and a stirring speed of 1000 rpm for 30 min to obtain SiO2 sol.

[0135] (2) At room temperature, rock wool short fibers with a length of 13 mm and a diameter of 12 μm were soaked in anhydrous ethanol for 20 min, with the mass ratio of rock wool short fibers to anhydrous ethanol being 1:50; then ultrasonic treatment was performed, with the ultrasonic frequency being 40 kHz and the ultrasonic time being 15 min. After ultrasonication, the material was transferred to an oven and dried at a temperature of 120 ° C for 4 h to obtain activated rock wool short fibers;

[0136] (3) The SiO2 sol prepared in step (1), the activated rock wool short fiber prepared in step (2), the reinforcing agent (N,N-dimethylformamide) and the dispersant (polyethylene glycol) were mixed in a ratio of 1:0.056:0.025:4.5×10 -3 The mass ratio of the raw materials was evenly mixed, and then sealed and stored at 60 ° C for 24 hours; the sealed and stored materials were transferred to a 60 ° C oven for heat aging for 48 hours; at room temperature, the heat-aged materials were immersed in a mixture of water and ethanol (the volume ratio of water to ethanol was 1:4) for polar solvent aging for 16 hours; the polar solvent-aged materials were first immersed in 60 ° C anhydrous ethanol for solvent replacement for 10 hours, and then immersed in 50 ° C 99.9% pure n-hexane for solvent replacement for 6 hours; after solvent replacement, The material was completely immersed in a mixed solution of trimethylchlorosilane and n-hexane for modification, wherein the volume ratio of trimethylchlorosilane to n-hexane was 1:9, the modification time was 3 days, and the modification temperature was 40°C; then it was washed with n-hexane with a purity of 99.9% at 50°C for 12 hours; the washed material was dried at temperatures of 60°C, 80°C, 100°C, 120°C, and 160°C, respectively, with the drying time for each stage being 2 hours, to obtain a SiO2 aerogel composite material.

[0137] Comparative Example 1

[0138] The preparation method of the SiO2 aerogel composite material is different from that of Example 1 except that no activated rock wool short fibers are added. Other conditions and parameters are the same as those of Example 1, and the method includes the following steps:

[0139] (1) Mix ethyl orthosilicate, ethanol, water and hydrochloric acid in the ratio of 1:5:10:10. -3 The mixture was stirred at a molar ratio of 1:1 and 1:2, and hydrolyzed at 90° C. for 4 h. After the reaction, the mixture was cooled to 25° C., and an alkaline catalyst (ammonia water) was added dropwise to the system to adjust the pH value of the system to 8.3. The polycondensation reaction was carried out at room temperature and a stirring speed of 1000 rpm for 30 min to obtain SiO2 sol.

[0140] (2) The SiO2 sol prepared in step (1), the reinforcing agent (N,N-dimethylformamide) and the dispersant (polyethylene glycol) were mixed at a ratio of 1:0.025:4.5×10 -3 The mass ratio of the two materials was uniformly mixed, and then sealed and stored at 60°C for 24 hours; the sealed and stored materials were transferred to a 60°C oven for heat aging for 48 hours; at room temperature, the heat-aged materials were immersed in a mixture of water and ethanol (the volume ratio of water to ethanol was 1:4) for polar solvent aging for 16 hours; the aged materials were first immersed in 60°C anhydrous ethanol for solvent replacement for 10 hours, and then immersed in 50°C 99.9% pure n-hexane for solvent replacement for 6 hours; the solvent-replaced materials were The material was completely immersed in a mixed solution of trimethylchlorosilane and n-hexane for modification. The volume ratio of trimethylchlorosilane to n-hexane was 1:9, the modification time was 3 days, and the modification temperature was 40°C. The material was then washed with 99.9% pure n-hexane at 50°C for 12 hours. The washed material was dried at 60°C, 80°C, 100°C, 120°C, and 160°C, respectively, with the drying time for each stage being 2 hours, to obtain a SiO2 aerogel composite material.

[0141] Comparative Example 2

[0142] The preparation method of the SiO2 aerogel composite material is different from that of Example 1, except that the amount of activated rock wool short fibers added in step (3) is too low, the mass ratio of SiO2 sol to activated rock wool short fibers is 1:0.01, and other conditions and parameters are the same as those of Example 1, and the method comprises the following steps:

[0143] (1) Mix ethyl orthosilicate, ethanol, water and hydrochloric acid in the ratio of 1:5:10:10. -3 The mixture was stirred at a molar ratio of 1:1 and 1:2, and hydrolyzed at 90° C. for 4 h. After the reaction, the mixture was cooled to 25° C., and an alkaline catalyst (ammonia water) was added dropwise to the system to adjust the pH value of the system to 8.3. The polycondensation reaction was carried out at room temperature and a stirring speed of 1000 rpm for 30 min to obtain SiO2 sol.

[0144] (2) At room temperature, rock wool short fibers with a length of 13 mm and a diameter of 12 μm were soaked in anhydrous ethanol for 20 min, with the mass ratio of rock wool short fibers to anhydrous ethanol being 1:50; then ultrasonic treatment was performed, with the ultrasonic frequency being 40 kHz and the ultrasonic time being 15 min. After ultrasonication, the material was transferred to an oven and dried at a temperature of 120 ° C for 4 h to obtain activated rock wool short fibers;

[0145] (3) The SiO2 sol prepared in step (1), the activated rock wool short fiber prepared in step (2), the reinforcing agent (N,N-dimethylformamide) and the dispersant (polyethylene glycol) were mixed in a ratio of 1:0.01:0.025:4.5×10 -3 The mass ratio of the two materials was evenly mixed, and then sealed and stored at 60°C for 24 hours; the sealed and stored materials were transferred to a 60°C oven for heat aging for 48 hours, and the heat-aged materials were immersed in a mixture of water and ethanol (the volume ratio of water to ethanol was 1:4) for polar solvent aging for 16 hours at room temperature; the aged materials were first immersed in 60°C anhydrous ethanol for solvent replacement for 10 hours, and then immersed in 50°C 99.9% pure n-hexane for solvent replacement for 6 hours; the solvent-replaced materials were The material was completely immersed in a mixture of trimethylchlorosilane and n-hexane for modification, wherein the volume ratio of trimethylchlorosilane to n-hexane was 1:9, the modification time was 3 days, and the modification temperature was 40°C; then it was washed with n-hexane with a purity of 99.9% at 50°C for 12 hours; after washing, the material was dried at temperatures of 60°C, 80°C, 100°C, 120°C, and 160°C, respectively, with the drying time for each stage being 2 hours, to obtain SiO2 aerogel composite materials.

[0146] Comparative Example 3

[0147] The preparation method of the SiO2 aerogel composite material is different from that of Example 1, except that no thermal aging is performed in step (3), and only polar solvent aging is used. Other conditions and parameters are the same as those of Example 1, and the method includes the following steps:

[0148] (1) Mix ethyl orthosilicate, ethanol, water and hydrochloric acid in the ratio of 1:5:10:10. -3 The mixture was stirred at a molar ratio of 1:1 and 1:2, and hydrolyzed at 90° C. for 4 h. After the reaction, the mixture was cooled to 25° C., and an alkaline catalyst (ammonia water) was added dropwise to the system to adjust the pH value of the system to 8.3. The polycondensation reaction was carried out at room temperature and a stirring speed of 1000 rpm for 30 min to obtain SiO2 sol.

[0149] (2) At room temperature, rock wool short fibers with a length of 13 mm and a diameter of 12 μm were soaked in anhydrous ethanol for 20 min, with the mass ratio of rock wool short fibers to anhydrous ethanol being 1:50; then ultrasonic treatment was performed, with the ultrasonic frequency being 40 kHz and the ultrasonic time being 15 min. After ultrasonication, the material was transferred to an oven and dried at a temperature of 120 ° C for 4 h to obtain activated rock wool short fibers;

[0150] (3) The SiO2 sol prepared in step (1), the activated rock wool short fiber prepared in step (2), the reinforcing agent (N,N-dimethylformamide) and the dispersant (polyethylene glycol) were mixed in a ratio of 1:0.07:0.025:4.5×10 -3 The material was mixed evenly in a mass ratio of 1:4 and then sealed and stored at 60°C for 24 hours; the sealed material was immersed in a mixture of water and ethanol (the volume ratio of water to ethanol was 1:4) for polar solvent aging for 16 hours; the material after polar solvent aging was first immersed in 60°C anhydrous ethanol for solvent replacement for 10 hours, and then immersed in 50°C 99.9% pure n-hexane for solvent replacement for 6 hours; the material after solvent replacement was completely immersed in a mixed solution of trimethylchlorosilane and n-hexane for modification, wherein the volume ratio of trimethylchlorosilane to n-hexane was 1:9, the modification time was 3 days, and the modification temperature was 40°C; then washed with 99.9% pure n-hexane at 50°C for 12 hours; the washed material was dried at temperatures of 60°C, 80°C, 100°C, 120°C, and 160°C, and the drying time for each stage was 2 hours to obtain a SiO2 aerogel composite material.

[0151] Comparative Example 4

[0152] The preparation method of the SiO2 aerogel composite material is different from that of Example 1, except that the activated rock wool short fibers are replaced with unactivated ordinary rock wool short fibers. Other conditions and parameters are the same as those of Example 1, and the method includes the following steps:

[0153] (1) Mix ethyl orthosilicate, ethanol, water and hydrochloric acid in the ratio of 1:5:10:10. -3 The mixture was stirred at a molar ratio of 1:1 and 1:2, and hydrolyzed at 90° C. for 4 h. After the reaction, the mixture was cooled to 25° C., and an alkaline catalyst (ammonia water) was added dropwise to the system to adjust the pH value of the system to 8.3. The polycondensation reaction was carried out at room temperature and a stirring speed of 1000 rpm for 30 min to obtain SiO2 sol.

[0154] (2) The SiO2 sol, rock wool short fibers, reinforcing agent (N,N-dimethylformamide) and dispersant (polyethylene glycol) prepared in step (1) were mixed in a ratio of 1:0.07:0.025:4.5×10 -3The mass ratio of the raw materials was evenly mixed, and then sealed and stored at 60°C for 24 hours; the sealed and stored materials were transferred to a 60°C oven for heat aging for 48 hours, and the heat-aged materials were immersed in a mixture of water and ethanol (the volume ratio of water to ethanol was 1:4) for polar solvent aging for 16 hours at room temperature; the polar solvent-aged materials were first immersed in 60°C anhydrous ethanol for solvent replacement for 10 hours, and then immersed in 50°C 99.9% pure n-hexane for solvent replacement for 6 hours; after solvent replacement, The material was completely immersed in a mixed solution of trimethylchlorosilane and n-hexane for modification, wherein the volume ratio of trimethylchlorosilane to n-hexane was 1:9, the modification time was 3 days, and the modification temperature was 40°C; then it was washed with n-hexane with a purity of 99.9% at 50°C for 12 hours; the washed material was dried at temperatures of 60°C, 80°C, 100°C, 120°C, and 160°C, respectively, with the drying time for each stage being 2 hours, to obtain a SiO2 aerogel composite material.

[0155] Effect Example 1

[0156] The test results of appearance, density, thermal conductivity, mechanical properties and electromagnetic shielding effectiveness of the products obtained in the above examples and comparative examples are shown in Table 1.

[0157] The thermal conductivity is measured using a thermal conductivity meter, and the test method refers to GB / T 10295-2008 "Insulating materials - Determination of steady-state thermal resistance and related properties - Heat flow meter method".

[0158] The compression strength is tested using an electronic universal testing machine, and the test method refers to GB / T 13480-2014 "Determination of compression properties of thermal insulation products for building use".

[0159] The test method for tensile strength refers to Chapter 10 of GB / T 17911-2018.

[0160] The electromagnetic shielding effectiveness is measured according to GJB8820-2015 “Measurement Method of Shielding Effectiveness of Electromagnetic Shielding Materials”.

[0161] Table 1

[0162]

[0163] As can be seen from the data in Table 1, this application adopts a new preparation process and a new composite structure, especially improves the formula of each material in the preparation process of SiO2 aerogel, and optimizes the design of the preparation parameters, so that the prepared new SiO2 aerogel composite material and SiO2 aerogel composite board not only exhibit better thermal insulation performance than general aerogel insulation materials, but also have lower density and thermal conductivity, excellent radiation protection performance, and solve the problem of material fragility and cracking. At the same time, the mechanical properties such as elastic modulus and tensile strength of the SiO2 aerogel composite material and SiO2 aerogel composite board are greatly enhanced, meeting the requirements of GB / T 34336-2017.

[0164] Finally, it should be noted that in this application, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0165] Although the present application has been disclosed above through the description of the specific embodiments of the present application, it should be understood that those skilled in the art may design various modifications, improvements or equivalents to the present application within the spirit and scope of the attached solutions. Such modifications, improvements or equivalents should also be considered to be included in the scope of protection claimed in the present application.

Claims

1. A method for preparing a SiO2 aerogel composite material, characterized in that: The steps include: (a1) a silicon source, an organic solvent, water, and an acidic catalyst are subjected to a hydrolysis reaction, cooled to room temperature, the pH value of the system is adjusted to 8 to 8.5, and subjected to a polycondensation reaction to obtain a SiO2 sol; (a2) soaking the rock wool staple fibers in a hydroxyl-containing polar organic solvent, ultrasonically treating the fibers, and drying the fibers to obtain activated rock wool staple fibers; (a3) uniformly mixing the SiO2 sol obtained in step (a1) and the activated rock wool short fibers obtained in step (a2), sealing and storing, sequentially subjecting the mixture to heat aging and polar solvent aging, then sequentially subjecting the mixture to solvent replacement with a polar organic solvent and a non-polar organic solvent, surface hydrophobic modification, washing, and normal pressure drying to obtain a SiO2 aerogel composite material; the mass ratio of the SiO2 sol to the activated rock wool short fibers is (14-18):1; Wherein, step (a1) and step (a2) are performed in no particular order; In step (a1), the silicon source includes at least one of tetraethyl orthosilicate, methyltriethoxysilane and methyltrimethoxysilane; the organic solvent includes an alcohol organic solvent and / or an alkane organic solvent; the acidic catalyst includes at least one of hydrochloric acid, nitric acid, sulfuric acid and hydrofluoric acid; the molar ratio of the silicon source, the organic solvent, the water and the acidic catalyst is 1: (2 to 10): (5 to 25): (10 -4 ~10 -2 ); In step (a1), the pH value of the system is adjusted to 8 to 8.5 by adding an alkaline catalyst; the alkaline catalyst comprises aqueous ammonia; In step (a2), the hydroxyl-containing polar organic solvent includes an alcohol solvent; the mass ratio of the rock wool short fibers to the hydroxyl-containing polar organic solvent is 1:(20-100); In step (a3), the heat aging temperature is 50-65° C., and the heat aging time is 24-50 h; the polar solvent aging temperature is room temperature, and the polar solvent aging time is 12-20 h; In step (a3), the polar solvent used in the polar solvent aging includes water and / or an alcohol solvent; when the polar solvent includes water and the alcohol solvent, the volume ratio of the water to the alcohol solvent is 1:(3-5); In step (a3), when the polar organic solvent is used for the solvent replacement, the polar organic solvent includes an alcohol solvent; when the non-polar organic solvent is used for the solvent replacement, the non-polar organic solvent includes an alkane solvent; In step (a3), the surface hydrophobic modification method comprises the following steps: completely immersing the material after solvent replacement in a modifier containing a trimethylsilyl group and a non-polar organic solvent, and mixing and reacting; the modifier containing a trimethylsilyl group comprises trimethylchlorosilane, and the non-polar organic solvent comprises an alkane solvent; the volume ratio of the modifier containing a trimethylsilyl group to the non-polar organic solvent is 1: (8 to 10), and the solvent comprises an alkane solvent; In step (a3), the atmospheric pressure drying method is a atmospheric pressure graded drying method, which is drying at 55-65°C, 75-85°C, 95-105°C, 115-125°C and 155-165°C in sequence, and the drying time in each stage is 2-5 hours.

2. The method for preparing the SiO2 aerogel composite material according to claim 1, wherein: The preparation method meets the following conditions: In step (a1), the temperature of the hydrolysis reaction is 70 to 100° C., and the time of the hydrolysis reaction is 2.5 to 5.5 hours; In step (a1), the polycondensation reaction is carried out under stirring conditions, the stirring speed is 1000-1400 rpm, the polycondensation reaction time is 20-40 min, and the polycondensation reaction temperature is room temperature.

3. The method for preparing the SiO2 aerogel composite material according to claim 2, wherein: The preparation method meets the following conditions: In step (a1), the organic solvent includes ethanol and / or n-hexane; In step (a1), the molar ratio of the silicon source, the organic solvent, the water and the acidic catalyst is 1:5:10:

10. -3 ; In step (a1), the temperature of the hydrolysis reaction is 80-90° C., and the time of the hydrolysis reaction is 3-4 hours; In step (a1), the polycondensation reaction time is 25 to 30 minutes.

4. The method for preparing the SiO2 aerogel composite material according to claim 1, wherein: The preparation method meets the following conditions: In step (a2), the length of the rock wool short fibers is 5 to 30 mm, and the diameter of the rock wool short fibers is 5 to 15 μm; In step (a2), the soaking temperature is room temperature and the soaking time is 20 to 60 minutes; In step (a2), the frequency of the ultrasound is 20 to 40 kHz, and the time of the ultrasound is 15 to 45 minutes; In step (a2), the drying temperature is 100-120° C., and the drying time is 3-4 hours.

5. The method for preparing the SiO2 aerogel composite material according to claim 4, wherein: The preparation method meets the following conditions: In step (a2), the length of the rock wool short fibers is 10 to 20 mm; In step (a2), the hydroxyl-containing polar organic solvent includes anhydrous ethanol; In step (a2), the mass ratio of the rock wool short fibers to the hydroxyl-containing polar organic solvent is 1:

50.

6. The method for preparing the SiO2 aerogel composite material according to any one of claims 1 to 4, characterized in that: The preparation method meets the following conditions: In step (a3), a reinforcing agent and / or a dispersant is added during the mixing process; the mass ratio of the SiO2 sol to the reinforcing agent is 1:(0.01-0.1); the mass ratio of the SiO2 sol to the dispersant is 1:(10 -3 ~5×10 -3 ); In step (a3), the sealed storage time is 10 to 36 hours, and the sealed storage temperature is 50 to 70° C.; In step (a3), when the polar organic solvent is used for the solvent replacement, the time of the solvent replacement is 8 to 12 hours, and the temperature of the solvent replacement is 50 to 65° C.; In step (a3), when the non-polar organic solvent is used for the solvent replacement, the time of the solvent replacement is 6 to 10 hours, and the temperature of the solvent replacement is 40 to 50° C.; In step (a3), the surface hydrophobic modification time is 2 to 4 days, and the surface hydrophobic modification temperature is 30 to 45° C.; In step (a3), the washing method comprises the following steps: immersing the surface-hydrophobically modified material in a non-polar organic solvent for washing, wherein the non-polar organic solvent comprises an alkane solvent; In step (a3), the washing time is 10 to 12 hours, and the washing temperature is 40 to 50°C.

7. The method for preparing the SiO2 aerogel composite material according to claim 6, wherein: The preparation method meets the following conditions: In step (a3), the reinforcing agent includes N,N-dimethylformamide; the dispersing agent includes at least one of sodium pyrophosphate, sodium hexametaphosphate, sodium polyacrylate, stearamide, cellulose and polyethylene glycol; the mass ratio of the SiO2 sol to the reinforcing agent is 1:0.025; the mass ratio of the SiO2 sol to the dispersing agent is 1:4.5×10 -3 ; In step (a3), the sealed storage time is 24 to 28 hours, and the sealed storage temperature is 60° C. In step (a3), the heat aging temperature is 60-65° C., and the heat aging time is 36-48 h; In step (a3), the polar solvent used for the polar solvent aging includes water and ethanol, and the polar solvent aging time is 16 hours; In step (a3), when the polar organic solvent is used for the solvent replacement, the polar organic solvent includes anhydrous ethanol, the solvent replacement time is 10 hours, and the solvent replacement temperature is 60° C.; In step (a3), when the non-polar organic solvent is used for the solvent replacement, the non-polar organic solvent includes n-hexane; In step (a3), the time for the surface hydrophobic modification is 2 to 4 days, and the temperature for the surface hydrophobic modification is 30 to 45°C.

8. The method for preparing the SiO2 aerogel composite material according to claim 7, wherein: The preparation method meets the following conditions: In step (a3), the material after the surface hydrophobic modification is immersed in a non-polar organic solvent for washing, and the non-polar organic solvent includes n-hexane.

9. A SiO2 aerogel composite material, characterized in that: The aerogel composite material is prepared by the preparation method of the SiO2 aerogel composite material according to any one of claims 1 to 8.

10. A method for preparing a SiO2 aerogel composite plate, characterized in that: The steps include: Step (b1) is the same as step (a1) in the method for preparing the SiO2 aerogel composite material according to claim 1 or 2, to obtain the SiO2 sol; Step (b2) is the same as step (a2) in the method for preparing the SiO2 aerogel composite material according to claim 1 or 3, to obtain the activated rock wool short fibers; Step (b3): uniformly mixing the SiO2 sol prepared in step (b1) and the activated rock wool short fibers prepared in step (b2), injecting the mixture into a grid, sealing and storing the mixture, sequentially subjecting the mixture to heat aging and polar solvent aging, sequentially subjecting the mixture to solvent replacement with a polar organic solvent and a non-polar organic solvent, performing surface hydrophobic modification, washing, and drying at normal pressure to obtain a SiO2 aerogel composite board; the mass ratio of the SiO2 sol to the activated rock wool short fibers is (14-18):1; Wherein, step (b1) and step (b2) are performed in no particular order; In step (b3), the grid comprises a three-dimensional grid; the three-dimensional grid comprises at least two mesh layers, and a connecting layer arranged between two adjacent mesh layers, the mesh layer comprises multiple groups of first and second woven wires interwoven with each other, the connecting layer comprises a third woven wire, the third woven wire is connected to the two adjacent mesh layers, and the extension directions of the first woven wire, the second woven wire and the third woven wire are different; with x, y, and z as the three axes of the three-dimensional rectangular coordinate system, the first woven wire is the x-direction woven wire, the second woven wire is the y-direction woven wire, and the third woven wire is the z-direction woven wire, the third woven wire is arranged in an "X" shape between the two mesh layers, and the "X"-shaped third woven wire is connected at its own intersection position, the mesh layer and the connecting layer are both woven by woven wires, the first woven wire and the second woven wire are cross-woven, the third woven wire is connected to the intersection of the first woven wire and the second woven wire of the two adjacent mesh layers, and the connection method of the third woven wire and the intersection of the first woven wire and the second woven wire of the two adjacent mesh layers is common weaving.

11. The method for preparing a SiO2 aerogel composite plate according to claim 10, wherein: The preparation method meets the following conditions: In step (b3), the material of the grid includes at least one of glass fiber, carbon fiber and basalt fiber; In step (b3), after the normal pressure drying operation, resin is coated on the surface of the obtained material.

12. The method for preparing a SiO2 aerogel composite plate according to claim 11, wherein: The preparation method meets the following conditions: In step (b3), the resin includes a radiation-proof resin.

13. The method for preparing the SiO2 aerogel composite plate according to claim 11, wherein: The preparation method meets the following conditions: In step (b3), the resin includes at least one of an organosilicon-modified boron phenolic resin, a xylene-modified boron phenolic resin, and a diphenyl ether formaldehyde resin.

14. The method for preparing a SiO2 aerogel composite plate according to claim 11, wherein: The preparation method meets the following conditions: The grid layer is planar or curved; The resin coating operation further includes an operation of covering the resin surface with fiber cloth.

15. The method for preparing a SiO2 aerogel composite plate according to claim 14, wherein: The preparation method meets the following conditions: The fiber cloth includes at least one of glass fiber cloth, polyester fiber cloth and carbon fiber cloth.

16. A SiO2 aerogel composite plate, characterized in that: The aerogel composite plate is prepared by the method for preparing the SiO2 aerogel composite plate according to any one of claims 10 to 15.

17. Use of the SiO2 aerogel composite material according to claim 9 or the SiO2 aerogel composite board according to claim 16 as a thermal insulation material in the construction field.

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