Aerogel material and method of making and use thereof

Abstract

The application provides an aerogel material and a preparation method and application thereof, and the preparation method comprises the following steps: (1) foaming polystyrene particles once to obtain pre-foamed particles; (2) soaking the pre-foamed particles obtained in the step (1) in a silica sol to obtain an intermediate A; (3) soaking the intermediate A obtained in the step (2) in a silane coupling agent solution to obtain an intermediate B; (4) sequentially performing alcohol solvent replacement and liquid protective medium replacement on the intermediate B obtained in the step (3) to obtain an intermediate C; and (5) foaming the intermediate C obtained in the step (4) twice, and cooling and aging to obtain the aerogel material. The preparation method adopts a template-permeation-sol-gel-replacement non-supercritical preparation aerogel mode, so that the aerogel material reaches A-grade non-combustible, and the heat insulation performance of the aerogel material can be effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of aerogel materials technology, specifically relating to an aerogel material, its preparation method, and its application. Background Technology

[0002] EPS (expandable polystyrene) foamed insulation materials are difficult to make to achieve Class A non-combustible properties and have high thermal conductivity. The foaming and cooling process absorbs moisture-containing air with high thermal conductivity, reducing the insulation performance of the foamed material. Furthermore, aerogel preparation suffers from long solvent replacement times, and obtaining high-quality aerogels requires a supercritical method, which is relatively limited. Therefore, it is urgently needed to develop a non-combustible, hydrophobic, ultra-low thermal conductivity insulation material and a non-supercritical preparation method.

[0003] CN110818349A discloses a silicon-modified EPS insulation board, comprising 43-45% 525 cement, 43-45% water, 0.9-1.1% water-repellent agent, 0.2-0.4% cellulose ether, 2.5-3.5% adhesive powder, 0.9-1.1% water-reducing agent, and 5-10% EPS graphite foam particles. The silicon-modified EPS insulation board has a thermal conductivity of 0.05 W / (m·K), but its flame-retardant properties are poor, making it unsuitable for applications in building materials, electrical appliances, chemical equipment, energy storage equipment, machinery, or oil extraction.

[0004] CN109486090A discloses an EPS foam board, the surface of which is covered with an auxiliary layer and a support. The auxiliary layer and support comprise 350-500 parts of ABS rubber powder, 46-82 parts of antimony trioxide, 30-47 parts of calcium-zinc composite heat stabilizer, 210-290 parts of silver nanoparticles, 134-184 parts of nano-silica, 71-145 parts of ethanol, 51-125 parts of dibutyl phthalate, 46-64 parts of crosslinking agent, and 20-34 parts of 2,6-di-tert-butyl-4-methylphenol. This EPS foam board, by incorporating the auxiliary layer, improves its strength and exhibits good flame retardant properties; however, its thermal insulation performance is poor, limiting its application range.

[0005] CN112876726A discloses a supercritical microfoamed polyurethane material, comprising 20-40 parts of polyester polyol, 20-50 parts of dodecylbenzene-2,4-diisocyanate, 2-10 parts of castor oil alcohol, 0.5-3 parts of dibutyltin dilaurate, 0.2-2 parts of elasticity modifier, 1-4 parts of surfactant, 0.5-2 parts of accelerator, and 1-3 parts of nucleating agent. This supercritical microfoamed polyurethane material effectively solves the problems of cracking, poor flexibility, compression deformation, and poor flame retardancy in materials; however, it has a high thermal conductivity, resulting in poor thermal insulation performance.

[0006] Existing aerogel materials suffer from several drawbacks, including insufficient flame retardancy, high thermal conductivity, and poor insulation, making it difficult to balance their properties and requiring a single, limited approach. Therefore, developing an aerogel composite material with good flame retardancy and low thermal conductivity, along with a non-supercritical preparation method, is a pressing issue in this field. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide an aerogel material, its preparation method, and its applications. The preparation method, through the selection of raw materials and optimization of processes, enables the thermal insulation aerogel material to possess excellent flame-retardant and thermal insulation properties, as well as a low thermal conductivity, thus fully meeting the application requirements of aerogel materials in thermal insulation materials, building materials, electrical appliances, chemical equipment, energy storage equipment, mechanical equipment, or oil extraction.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing an aerogel material, the method comprising the following steps:

[0010] (1) The expandable polystyrene particles are foamed once to obtain pre-foamed particles;

[0011] (2) The pre-foamed particles obtained in step (1) are immersed in silica sol to obtain intermediate A;

[0012] (3) The intermediate A obtained in step (2) is soaked in a silane coupling agent solution to obtain intermediate B;

[0013] (4) The intermediate B obtained in step (3) is subjected to alcohol solvent replacement and liquid protective medium replacement in sequence to obtain intermediate C;

[0014] (5) The intermediate C obtained in step (4) is foamed a second time and cooled and aged to obtain the aerogel material.

[0015] In the preparation method of the aerogel material provided by the present invention, expandable polystyrene (EPS) particles are used as templates. First, the (EPS) particles are foamed once to obtain pre-foamed particles, in which pores are formed in the microsphere cavities. Then, the pre-foamed particles are immersed in silica sol. Silica sol has strong permeability, which allows the silica sol to penetrate into the interior of the pre-foamed particles. Then, a silane coupling agent is added, which reacts with water (from silica sol) to form stable siloxane groups, which promotes the silica sol to gel and forms siloxane bonds between the gel and the EPS cavity membrane, playing a role in cross-linking modification. In step (4), excess water is replaced with alcohol solvent, and then excess alcohol solvent is replaced with liquid protective medium, thereby avoiding the collapse of the nanopores of silica aerogel and improving the heat preservation and insulation performance. The intermediate C that has completed the liquid protective medium replacement is foamed a second time. The membrane bubble is bonded and formed under the expansion pressure of foaming. After cooling and aging, the aerogel material is obtained. This invention provides a non-supercritical method for preparing aerogels, which involves a process of "template-permeation-sol-gel-displacement-foaming". The resulting aerogel material contains silica aerogel, which has excellent flame retardant properties and can achieve Class A non-combustible performance. At the same time, the silica aerogel has good stability under the cross-linking effect of EPS film and silane coupling agent, effectively avoiding the collapse and deformation of the porous structure and exhibiting excellent thermal insulation properties.

[0016] Preferably, the diameter of the expandable polystyrene particles is 0.5-1 mm, for example, it can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0017] Preferably, the volume ratio of the pre-foamed particles to the expandable polystyrene particles is (2-10):1, which can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, and specific values ​​between the above-mentioned values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0018] As a preferred embodiment of the present invention, the primary foaming expands the volume of EPS particles by 2-10 times, which then serve as templates. Subsequent steps of infiltration-sol-gel-displacement-foaming are then performed to obtain a Class A non-combustible aerogel material. If the volume expansion factor of the primary foaming is too small (<2), pre-foamed particles with suitable porosity and internal cavities cannot be formed, preventing effective penetration of the silica sol and reducing the flame retardancy and thermal insulation properties of the aerogel material. If the volume expansion factor of the primary foaming is too large (>10), secondary foaming will fail to form the desired shape, resulting in dispersed particles and preventing the acquisition of an ideal aerogel material.

[0019] Preferably, the solid content of the silica sol is 10-40%, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0020] Preferably, the dispersion medium (solvent) in the silica sol is water.

[0021] Preferably, the soaking time in step (2) is 2-24h, for example, it can be 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0022] Preferably, the soaking pressure in step (2) is 0-10 MPa, for example, it can be 0 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0023] As a preferred embodiment of the present invention, the soaking time in step (2) is 2-24 hours to allow the silica sol to fully penetrate into the interior of the pre-foamed particles; the soaking can be a single soaking (2-24 hours) or multiple soakings, with a total soaking time of 2-24 hours. The soaking can be carried out under normal pressure (without additional pressure) or under pressure (0-10 MPa), with pressure helping to improve the penetration efficiency of the silica sol.

[0024] Preferably, step (2) further includes a draining and rinsing step after soaking to remove excess silica sol from the surface.

[0025] Preferably, the solvent of the silane coupling agent solution is an alcohol solvent, such as any one or a combination of at least two of methanol, ethanol, propanol, isopropanol, butanol, and isobutanol, with ethanol being preferred.

[0026] Preferably, the mass concentration of the silane coupling agent in the silane coupling agent solution is 1-10%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0027] Preferably, the silane coupling agent comprises any one or a combination of at least two of methyltrimethoxysilane, vinyltriethoxysilane solution, vinyltrimethoxysilane solution, and vinyltri(β-methoxyethoxy)silane, with methyltrimethoxysilane being the most preferred.

[0028] Preferably, the soaking time in step (3) is 10 min to 24 h, for example, it can be 10 min, 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h, 17 h, 18 h, 19 h, 20 h, 21 h, 22 h, 23 h, 24 h, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0029] Preferably, the soaking pressure in step (3) is 0-10 MPa, for example, it can be 0 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0030] As a preferred embodiment of the present invention, the soaking time in step (3) is 10 min to 24 h, so that the silane coupling agent can fully enter intermediate A and undergo a full hydrolysis reaction with the water in the silica sol, promoting silica sol gelation and forming silicon-oxygen bonds on the gel and EPS cavity membrane, thus completing the crosslinking modification. The soaking can be a single soaking (10 min to 24 h) or multiple soakings, with a total soaking time of 10 min to 24 h. The soaking can be carried out under normal pressure (without additional pressure) or under pressure (pressure 0-10 MPa).

[0031] Preferably, the alcohol solvent used for the alcohol solvent replacement includes any one or a combination of at least two of methanol, ethanol, n-propanol, and isopropanol.

[0032] Preferably, the alcohol solvent replacement method includes: immersing the intermediate B in an alcohol solvent to complete the alcohol solvent replacement.

[0033] Preferably, the soaking time in the alcohol solvent is 1-24 hours, for example, it can be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0034] Preferably, the immersion pressure in the alcohol solvent is 0-10 MPa, for example, it can be 0 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0035] As a preferred embodiment of the present invention, the soaking (alcohol solvent replacement) in the alcohol solvent is carried out for 1-24 hours to ensure that the alcohol solvent fully replaces the excess water in the intermediate B, thus avoiding the adverse effects of water on the thermal conductivity. The gel and EPS cavity in the intermediate B are insoluble in the alcohol solvent, therefore they will not affect the composition and structure of the intermediate B. The soaking can be a single soaking (single alcohol solvent replacement, time 1-24 hours) or multiple soakings (multiple alcohol solvent replacements, total time 1-24 hours). The soaking (alcohol solvent replacement) in the alcohol solvent can be carried out under normal pressure (without additional pressure) or under pressure (pressure 0-10 MPa), with pressure helping to improve the efficiency of alcohol solvent replacement.

[0036] Preferably, the liquid protective medium used for the liquid protective medium replacement includes any one or a combination of at least two of liquid carbon dioxide, liquid nitrogen, and liquid argon, with liquid carbon dioxide being the most preferred.

[0037] Preferably, the method for replacing the liquid protective medium includes: immersing the product after alcohol solvent replacement in a liquid protective medium to complete the replacement of the liquid protective medium.

[0038] As a preferred technical solution of the present invention, in the preparation method, the selection of liquid protective medium replacement can replace the remaining alcohol solvent, and at the same time can act as a foaming agent to promote foaming.

[0039] Preferably, the immersion time in the liquid protective medium is 2-24 hours, for example, it can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0040] Preferably, the immersion pressure in the liquid protective medium is 0-10 MPa, for example, it can be 0 MPa, 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0041] As a preferred embodiment of the present invention, the immersion (liquid protective medium replacement) time in the liquid protective medium is 2-24 hours to ensure that the liquid protective medium fully replaces the remaining alcohol solvent; the immersion can be a single immersion (single liquid protective medium replacement, time 2-24 hours) or multiple immersions (multiple liquid protective medium replacements, total time 2-24 hours). The immersion (liquid protective medium replacement) in the liquid protective medium can be carried out under normal pressure (without additional pressure) or under pressure (pressure 0-10 MPa), and pressure helps to improve the efficiency of liquid protective medium replacement.

[0042] Preferably, the temperature of the secondary foaming is 100-200℃, for example, it can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0043] Preferably, the secondary foaming time is 5-20 minutes, for example, it can be 5 minutes, 8 minutes, 10 minutes, 12 minutes, 15 minutes, 18 minutes, 20 minutes, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0044] Preferably, the cooling aging is carried out in a protective atmosphere.

[0045] As a preferred technical solution of the present invention, in the preparation method, after the secondary foaming is completed, the material is cooled (preferably naturally cooled) and aged in a protective atmosphere, which can make the porous structure in the aerogel material more uniform and stable, avoid deformation or collapse of the porous structure, and thus have better thermal insulation performance.

[0046] Preferably, the cooling aging time is 2-24 hours, for example, it can be 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0047] Preferably, the preparation method specifically includes the following steps:

[0048] (1) The expandable polystyrene particles are foamed once at 90-100℃ to obtain pre-foamed particles; the volume ratio of the pre-foamed particles to the expandable polystyrene particles is (2-10):1.

[0049] (2) Soak the pre-foamed particles obtained in step (1) in silica sol for 2-24 hours to obtain intermediate A;

[0050] (3) The intermediate A obtained in step (2) is soaked in a silane coupling agent solution for 10 min-24 h to obtain intermediate B; the solvent of the silane coupling agent solution is an alcohol solvent, wherein the mass concentration of the silane coupling agent is 1-10%;

[0051] (4) The intermediate B obtained in step (3) is immersed in an alcohol solvent for 1-24 hours to complete the alcohol solvent replacement; the product after the alcohol solvent replacement is immersed in a liquid protective medium for 2-24 hours to complete the liquid protective medium replacement, and intermediate C is obtained; the liquid protective medium includes any one or a combination of at least two of liquid carbon dioxide, liquid nitrogen, and liquid argon.

[0052] (5) After the intermediate C obtained in step (4) is foamed a second time, it is cooled and aged in a protective atmosphere for 2-24 hours to obtain the aerogel material; the temperature of the second foaming is 100-200℃ and the time is 5-20 minutes.

[0053] In a second aspect, the present invention provides an aerogel material, which is prepared by the preparation method described in the first aspect.

[0054] Preferably, the density of the aerogel material is 10-50 kg / m³. 3 For example, it can be 12kg / m 3 15kg / m 3 18kg / m 3 20kg / m 3 22kg / m 3 25kg / m 3 28kg / m 330kg / m 3 35kg / m 3 40kg / m 3 Or 45kg / m 3 As well as the specific point values ​​between the above point values, due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0055] Preferably, the thermal conductivity of the aerogel material is <0.03 W / (m·k), for example, it can be 0.01 W / (m·k), 0.011 W / (m·k), 0.013 W / (m·k), 0.015 W / (m·k), 0.017 W / (m·k), 0.019 W / (m·k), 0.02 W / (m·k), 0.022 W / (m·k), 0.025 W / (m·k), or 0.028 W / (m·k), etc., more preferably ≤0.02 W / (m·k), and even more preferably ≤0.018 W / (m·k).

[0056] Thirdly, the present invention provides an application of the aerogel material as described in the second aspect in thermal insulation materials, building materials, electrical appliances, chemical equipment, energy storage equipment, mechanical equipment, or oil extraction.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] The aerogel material preparation method provided by this invention uses EPS as a template and adopts a non-supercritical preparation process of "template-infiltration-sol-gel-displacement-foaming". Through the selection of raw materials and optimization of process design, the aerogel material has excellent flame retardant properties and can achieve Class A non-combustible effect. At the same time, the silica aerogel has good stability under the cross-linking effect of EPS film and silane coupling agent, avoiding the collapse and deformation of porous structure, and has excellent thermal insulation performance. Its thermal conductivity is ≤0.018W / (m·k), which is a high-quality non-combustible, hydrophobic, and ultra-low thermal conductivity insulation material. Detailed Implementation

[0059] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0060] The experimental materials used in the embodiments and comparative examples of this invention are all commercially available products. Among them, expandable polystyrene (EPS) particles are commercially available products with an average diameter of 0.8 mm; silica sol is a commercially available product with a solid content of 30%.

[0061] Example 1

[0062] An aerogel material and its preparation method, the preparation method specifically including the following steps:

[0063] (1) The EPS particles were foamed once at 100℃ and normal pressure. The resulting microspheres were screened and graded with diameters of 5mm, 6mm, 7mm, 8mm, 9mm and 10mm respectively. The microspheres with a diameter of 5mm were taken as pre-foamed particles.

[0064] (2) The pre-foamed particles obtained in step (1) are immersed in silica sol with a solid content of 30% at 1MPa for 12h, taken out, and the excess silica sol on the surface is drained to obtain intermediate A;

[0065] (3) The intermediate A obtained in step (2) was placed in a methyltrimethoxysilane solution (the mass concentration of methyltrimethoxysilane was 5% and the solvent was anhydrous ethanol) and soaked at 1 MPa for 12 h to obtain intermediate B;

[0066] (4) Place the intermediate B obtained in step (3) in ethanol and soak it at 1 MPa for 12 h to complete the alcohol solvent replacement; place the product after alcohol solvent replacement in liquid carbon dioxide and soak it at 1 MPa for 12 h to complete the liquid protective medium replacement to obtain intermediate C;

[0067] (5) Take 20g of intermediate C obtained in step (4), place it in a 1L foaming mold, heat it to 120°C with supersaturated steam, keep it warm for 15min, and complete the second foaming; then place the product obtained from the second foaming in a carbon dioxide atmosphere to cool and age for 12h to obtain the aerogel material.

[0068] Example 2

[0069] An aerogel material and its preparation method are disclosed. The only difference between this material and Example 1 is that the soaking pressure in steps (2), (3) and (4) is 10 MPa and the soaking time is 1 h. All other raw materials, process steps and parameters are the same as in Example 1.

[0070] Example 3

[0071] An aerogel material and its preparation method are disclosed. The only difference between this material and Example 1 is that the soaking pressure in steps (2), (3) and (4) is 10 MPa and the soaking time is 5 h. The other raw materials, process steps and parameters are the same as in Example 1.

[0072] Example 4

[0073] An aerogel material and its preparation method are disclosed. The only difference between the aerogel material and Example 1 is that the soaking pressure in steps (2), (3) and (4) is 10 MPa and the soaking time is 10 h. The other raw materials, process steps and parameters are the same as those in Example 1.

[0074] Example 5

[0075] An aerogel material and its preparation method are different from those in Example 1 only in that the cooling aging in step (5) is carried out in a room temperature air atmosphere for 12 hours; the other raw materials, process steps and parameters are the same as those in Example 1.

[0076] Example 6

[0077] An aerogel material and its preparation method are disclosed. The only difference between this material and Example 1 is that in step (1), microspheres with a diameter of 10 mm are used as pre-foamed particles; the other raw materials, process steps and parameters are the same as in Example 1.

[0078] Comparative Example 1

[0079] An aerogel material and its preparation method are disclosed, wherein the aerogel material is conventionally foamed from EPS particles, and the specific method is as follows:

[0080] Pre-foamed particles were obtained by the method in step (1) of Example 1. The pre-foamed particles were then placed in a 1L foaming mold and heated to 120°C with supersaturated steam for 15 minutes to complete the secondary foaming. The product obtained from the secondary foaming was then placed in a carbon dioxide atmosphere for cooling and aging for 12 hours to obtain the aerogel material.

[0081] Comparative Example 2

[0082] An aerogel material and its preparation method, the preparation method specifically including the following steps:

[0083] Intermediate B was prepared by the method in steps (1)-(3) of Example 1; 20g of intermediate B was placed in a 1L foaming mold, heated to 120°C with supersaturated steam, and kept warm for 15min to complete the secondary foaming; then the product obtained from the secondary foaming was placed in a carbon dioxide atmosphere to cool and age for 12h to obtain the aerogel material.

[0084] Comparative Example 3

[0085] An aerogel material and its preparation method are different from those in Example 1 only in that step (4) only involves alcohol solvent replacement (specific parameters are the same as in Example 1) and does not involve liquid protective medium replacement; other raw materials, process steps and parameters are the same as in Example 1.

[0086] Comparative Example 4

[0087] An aerogel material and its preparation method are different from those in Example 1 only in that step (4) does not involve alcohol solvent replacement, but only liquid protective medium replacement (the specific parameters are the same as in Example 1); other raw materials, process steps and parameters are the same as in Example 1.

[0088] Comparative Example 5

[0089] An aerogel material and its preparation method are different from those in Example 1 only in that the step (3) of soaking in methyltrimethoxysilane solution is not performed. That is, the intermediate A obtained in step (2) directly enters step (4) for alcohol solvent replacement and liquid protective medium replacement. Other raw materials, process steps and parameters are the same as those in Example 1.

[0090] Comparative Example 6

[0091] An aerogel material and its preparation method are different from those in Example 1 only in that the first foaming step (1) is not performed, that is, the EPS particles directly enter the step (2) to be soaked in silica sol; the other raw materials, process steps and parameters are the same as those in Example 1.

[0092] Examples 1-6 and Comparative Examples 1-6 were used to test the performance of the aerogel materials provided. The specific methods are as follows:

[0093] (1) Thermal conductivity: The test was conducted according to the standard GB / T 10294-2008 Determination of steady-state thermal resistance and related properties of thermal insulation materials by the protective hot plate method.

[0094] (2) Combustion rating: Tested according to the standard GB / T 8624-2012 Classification of Combustion Performance of Building Materials and Products;

[0095] The test results are shown in Table 1:

[0096] Table 1

[0097] <![CDATA[Density (kg / m 3 )]]> Thermal conductivity (W / (mk)) flammability rating Example 1 20 0.0145 Class A Non-combustible Example 2 20 0.0160 Class A Non-combustible Example 3 20 0.0155 Class A Non-combustible Example 4 20 0.0145 Class A Non-combustible Example 5 20 0.0165 Class A Non-combustible Example 6 20 0.040 Class B Flame Retardant Comparative Example 1 20 0.0420 Class B combustible Comparative Example 2 20 0.038 Class A Non-combustible Comparative Example 3 20 0.032 Class A Non-combustible Comparative Example 4 20 0.038 Class A Non-combustible Comparative Example 5 20 0.022 Class A Non-combustible Comparative Example 6 20 0.041 Class B combustible

[0098] As can be seen from the data in Table 1, the aerogel materials provided in Examples 1-5 of the present invention have a low thermal conductivity, which is as low as 0.0145-0.0165 W / (m·k), and can achieve Class A non-combustible performance in terms of combustion.

[0099] Specifically, this invention employs a non-supercritical method for preparing aerogels, which involves template-permeation-sol-gel-displacement, enabling the aerogel material to achieve Class A non-combustibility. Comparison of Examples 1-4 shows that increasing pressure during the displacement process improves the displacement rate. Comparison of Examples 1 and 5 shows that aging under a protective atmosphere makes the porous structure in the aerogel material more uniform and stable, preventing deformation or collapse and thus providing better thermal insulation performance. Comparison of Examples 1 and 6 shows that if the expansion ratio of the primary foaming is too high, it will affect the formability of the secondary foaming, resulting in a certain dispersion of particles and consequently impacting the overall performance of the aerogel material.

[0100] The preparation method provided by this invention uses EPS particles as templates to allow silica sol to penetrate into the interior of pre-foamed particles. Then, a silane coupling agent is used to modify and gel the particles, forming silicon-oxygen bonds between the gel and the EPS cavity membrane. After alcohol solvent replacement and liquid protective medium replacement, excess water is removed to prevent the collapse of the nanopores of the silica aerogel and improve its heat preservation and insulation properties. Finally, after secondary foaming and cooling aging, a non-flammable, hydrophobic aerogel material with ultra-low thermal conductivity is obtained. Comparative Example 1 is a polystyrene foam material formed by conventional EPS particle foaming, which has a high thermal conductivity and poor insulation. Comparative Examples 2-4 did not undergo alcohol solvent replacement and / or liquid protective medium replacement, resulting in collapse of the aerogel micropores during the drying process, thus leading to a higher thermal conductivity of the product. The preparation method of Comparative Example 5 did not include the immersion step of silane coupling agent solution, resulting in a product that is not hydrophobic and, due to its hydrophilicity, easily absorbs moisture, leading to a higher thermal conductivity of the product. The preparation method of Comparative Example 6 did not perform a primary foaming of EPS particles, making it impossible to form pre-foamed particles with suitable cavities and pores. This resulted in the silica sol not being able to effectively penetrate into the interior of the EPS particles, thus failing to obtain an effective aerogel material with a high thermal conductivity and a combustion rating that could not reach Class A.

[0101] The applicant declares that the aerogel material, its preparation method, and its application are illustrated by the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing an aerogel material, characterized in that, The preparation method includes the following steps: (1) The expandable polystyrene particles are foamed once to obtain pre-foamed particles; (2) The pre-foamed particles obtained in step (1) are immersed in silica sol to obtain intermediate A; (3) The intermediate A obtained in step (2) is soaked in a silane coupling agent solution to obtain intermediate B; (4) The intermediate B obtained in step (3) is subjected to alcohol solvent replacement and liquid protective medium replacement in sequence to obtain intermediate C; (5) The intermediate C obtained in step (4) is foamed a second time and cooled and aged to obtain the aerogel material; The diameter ratio of the pre-foamed particles to the expandable polystyrene particles is (2-10):1; The silane coupling agent includes any one or a combination of at least two of methyltrimethoxysilane, vinyltriethoxysilane solution, vinyltrimethoxysilane solution, and vinyltri(β-methoxyethoxy)silane; The liquid protective medium used for the replacement of the liquid protective medium includes liquid carbon dioxide.

2. The preparation method according to claim 1, characterized in that, The temperature for the first foaming is 90-100℃.

3. The preparation method according to claim 1, characterized in that, The solid content of the silica sol is 10-40%.

4. The preparation method according to claim 1, characterized in that, The soaking time in step (2) is 2-24 h, and the pressure is 0-10 MPa.

5. The preparation method according to claim 1, characterized in that, Step (2) includes the steps of draining and washing after soaking.

6. The preparation method according to claim 1, characterized in that, The solvent for the silane coupling agent solution is an alcohol solvent.

7. The preparation method according to claim 1, characterized in that, The mass concentration of the silane coupling agent in the silane coupling agent solution is 1-10%.

8. The preparation method according to claim 1, characterized in that, The soaking time in step (3) is 10 min-24 h, and the pressure is 0-10 MPa.

9. The preparation method according to claim 1, characterized in that, The alcohol solvent used for the alcohol solvent replacement includes any one or a combination of at least two of methanol, ethanol, n-propanol, and isopropanol.

10. The preparation method according to claim 1, characterized in that, The method of alcohol solvent replacement includes: immersing the intermediate B in an alcohol solvent to complete the alcohol solvent replacement.

11. The preparation method according to claim 10, characterized in that, The soaking time in the alcohol solvent is 1-24 hours, and the pressure is 0-10 MPa.

12. The preparation method according to claim 1, characterized in that, The method for replacing the liquid protective medium includes: immersing the product after alcohol solvent replacement in a liquid protective medium to complete the replacement of the liquid protective medium.

13. The preparation method according to claim 12, characterized in that, The immersion time in the liquid protective medium is 2-24 h, and the pressure is 1-10 MPa.

14. The preparation method according to claim 1, characterized in that, The secondary foaming temperature is 100-200℃, and the time is 5-20 min.

15. The preparation method according to claim 1, characterized in that, The cooling aging is carried out in a protective atmosphere.

16. The preparation method according to claim 1, characterized in that, The cooling aging time is 2-24 hours.

17. The preparation method according to claim 1, characterized in that, The preparation method specifically includes the following steps: (1) The expandable polystyrene particles are foamed once at 90-100℃ to obtain pre-foamed particles; the diameter ratio of the pre-foamed particles to the expandable polystyrene particles is (2-10):

1. (2) Soak the pre-foamed particles obtained in step (1) in silica sol for 2-24 h to obtain intermediate A; (3) The intermediate A obtained in step (2) is soaked in a silane coupling agent solution for 10 min-24 h to obtain intermediate B; the solvent of the silane coupling agent solution is an alcohol solvent, wherein the mass concentration of the silane coupling agent is 1-10%; (4) The intermediate B obtained in step (3) is soaked in an alcohol solvent for 1-24 h to complete the alcohol solvent replacement; the product after the alcohol solvent replacement is soaked in a liquid protective medium for 2-24 h to complete the liquid protective medium replacement, and intermediate C is obtained; the liquid protective medium includes liquid carbon dioxide; (5) After the intermediate C obtained in step (4) is foamed a second time, it is cooled and aged in a protective atmosphere for 2-24 h to obtain the aerogel material; the temperature of the second foaming is 100-200℃ and the time is 5-20 min.

18. An aerogel material, characterized in that, The aerogel material is prepared using the preparation method described in any one of claims 1-17.

19. The application of the aerogel material as described in claim 18 in thermal insulation materials, building materials, electrical appliances, chemical equipment, energy storage equipment, mechanical equipment, or oil extraction.