aerogel complex

Abstract

To provide an aerogel composite having superior performance.SOLUTION: According to an embodiment, an aerogel composite includes a porous substrate and an aerogel filled into the voids inside the porous substrate. The degree of hydrophobicity represented by [SAN / SAM] is 10.0 or more, where SAM denotes a BET specific surface area based on the water vapor adsorption method and SAN denotes a BET specific surface area based on the nitrogen gas adsorption method.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to an aerogel composite. [Background technology]

[0002] Insulation materials are essential for effectively utilizing thermal energy and promoting energy conservation. Various insulation materials, such as foamed and fibrous insulation materials and vacuum insulation materials, are used, mainly in automobiles and housing applications.

[0003] In recent years, aerogels have attracted attention as materials with excellent thermal insulation properties. Aerogels are a general term for dry gels with low density and high porosity, and are porous materials obtained by drying wet gels. Since silica aerogels and the like are extremely brittle and can be very difficult to handle on their own, materials that combine aerogels with other materials (for example, foams) have been investigated (see Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2010-47710 [Overview of the project] [Problems that the invention aims to solve]

[0005] The increasing demand for energy conservation and the miniaturization of electrical products are creating a need for aerogel composites with higher performance.

[0006] Therefore, the object of the present invention is to provide a gel composite having excellent performance. [Means for solving the problem]

[0007] One embodiment of the present invention is It comprises a porous substrate and an aerogel filled in the voids inside the porous substrate, Let the BET specific surface area based on the water vapor adsorption method be SA M and the BET specific surface area based on the nitrogen gas adsorption method be SA N When, [SA N / SA M shows that the degree of hydrophobicity is 10.0 or more, which is characterized by an aerogel composite.

[0008] It is preferable that the aerogel is a silica aerogel. The aerogel composite preferably has a thermal conductivity of less than 0.0160 W / m·K. The porous substrate is preferably a foam. The aerogel composite is preferably a heat insulating material.

Effect of the Invention

[0009] According to the present invention, a gel composite having excellent performance is provided.

Mode for Carrying Out the Invention

[0010] In the following, when the upper limit value and the lower limit value are separately described, a numerical range obtained by combining any upper limit value and any lower limit value is regarded as being substantially disclosed.

[0011] In the following, when a certain compound is described, its isomers are also regarded as being described at the same time.

[0012] In the following, when simply referred to as "density", it indicates the apparent density measured in accordance with JIS K7222:2005 "Foamed Plastics and Rubbers - Method for Determining Apparent Density".

[0013] In the following, unless otherwise specified, various measurements are carried out with the environmental temperature being room temperature (23°C).

[0014] Hereinafter, the structure / components, physical properties / characteristics, manufacturing method, uses, etc. of the aerogel composite will be specifically described, but the present invention is not limited thereto.

[0015] <<<Structure / components>>> The aerogel composite relating to this disclosure includes a porous substrate and an aerogel filled in the voids inside the porous substrate.

[0016] <<Porous base material>> Porous substrates are materials that have many pores capable of holding aerogel.

[0017] The size of the pores in the porous substrate is not particularly limited. The porous substrate may be, for example, a microporous material, a mesoporous material, a macroporous material, or the like.

[0018] The pores in the porous structure are preferably interconnected. Having interconnected pores in the porous structure makes it easier to adequately fill it with aerogel, which tends to result in superior thermal insulation properties for the composite.

[0019] Examples of porous substrates include foams, fibrous substrates formed by fibers (e.g., woven or nonwoven fabrics), and substrates forming a complex three-dimensional framework (e.g., porous ceramic substrates). From the viewpoint of balancing the thermal insulation, processability, and ease of manufacture of the aerogel composite, the porous substrate is preferably a foam or nonwoven fabric, and from the viewpoint of further enhancing the retention of the aerogel, it is particularly preferably a foam.

[0020] The fibers constituting the fibrous base material can include metal fibers made of metals such as stainless steel and aluminum, organic fibers made of organic materials such as polyester, polyolefin, polyvinyl chloride, acrylic, polyimide, polyamide, and cellulose, and inorganic fibers made of inorganic materials such as glass, carbon, silica, rock wool, and ceramics.

[0021] Examples of the foam include known foams such as olefin resin foam, acrylic resin foam, urethane resin foam, vinyl acetate resin foam, vinyl chloride resin foam, epoxy resin foam, rubber foam, silicone resin foam, melamine resin foam, and polyimide resin foam.

[0022] The foam may be thermally compressed. By thermally compressing the foam, it becomes easier to set the density, thickness, air permeability, etc. of the foam base material within a desired range, and the heat insulation property, ease of manufacture, etc. of the resulting aerogel composite can be enhanced.

[0023] Also, the foam may have a skin layer. The skin layer is generally a region having a higher density (fewer air bubbles) than the central part of the foam. When the foam has a skin layer, it is easier to prevent the detachment (powder falling) of the aerogel when using the aerogel composite.

[0024] For the method of thermally compressing the foam and the method of forming a skin layer on the foam, the methods disclosed in JP-A-2022-011146 etc. can be used.

[0025] The density of the porous base material is 0.01 g / cm 3 or more, 0.02 kg / m 3 or more, 0.05 kg / m 3 or more, 0.08 g / cm 3 or more, or 0.10 g / cm 3 or more, and preferably 2.0 g / cm 3 or less, 1.0 g / cm 3 or less, 0.80 g / cm 3 or less, 0.60 kg / m 3 or less, 0.40 g / cm 3 or less, or 0.25 g / cm 3 or less. When the density of the porous base material is within such a range, it is easy to obtain excellent heat insulation properties.

[0026] The thickness of the porous substrate (or the aerogel composite) can be appropriately changed depending on the application and is not particularly limited. From the viewpoint of improving the thermal insulation, processability, ease of manufacture, etc. of the aerogel composite in a balanced manner, the thickness of the porous substrate (or the aerogel composite) is preferably 0.1 mm or more, 0.2 mm or more, 0.5 mm or more, or 1.0 mm or more, and also preferably 100.0 mm or more, 50.0 mm or more, 20.0 mm or more, 10.0 mm or less, or 5.0 mm or less.

[0027] The shape of the porous substrate (or the shape of the aerogel composite) can be changed as appropriate depending on the application and is not particularly limited.

[0028] <<Aerogel>> The aerogel is not particularly limited and includes inorganic aerogels such as silica aerogel and alumina aerogel, organic aerogels such as resorcinol-formaldehyde aerogel (RF aerogel) and cellulose nanofiber aerogel (CNF aerogel), carbon aerogel, and mixtures thereof. Silica aerogel is preferred.

[0029] The density of aerogel is 0.001 g / cm³. 3 More than 0.01kg / m 3 More than 0.05kg / m 3 More than 0.08g / cm 3 Above, or 0.10 g / cm³ 3 Preferably, it should be 2.0 g / cm³ or more, and also 2.0 g / cm³. 3 Below 1.0g / cm 3 Below 0.80g / cm 3 Below 0.60kg / m 3 Below 0.40g / cm 3 Below 0.25g / cm 3 , or 0.20 g / cm³ 3 The following is preferable. When the density of the aerogel is within this range, it is easier to obtain excellent heat insulation properties.

[0030] <<<Physical properties / properties>>> <<Hydrophobicity>> The aerogel composite has a BET specific surface area based on water vapor adsorption. M The BET specific surface area based on the nitrogen gas adsorption method is SA N When that happens, [SA N / SA M The degree of hydrophobicity, indicated by [ ], is preferably 10.0 or higher, 12.0 or higher, or 14.0 or higher. The upper limit of the degree of hydrophobicity is not particularly limited, but for example, it is 50.0 or lower, 40.0 or lower, or 30.0 or lower. Aerogel composites with a degree of hydrophobicity within this range are thought to exhibit excellent thermal insulation because the substitution rate of hydroxyl groups on the aerogel surface with hydrophobic groups is high, and shrinkage of the gel over time can be suppressed.

[0031] The BET specific surface area based on the water vapor adsorption method and the BET specific surface area based on the nitrogen gas adsorption method shall be the values ​​measured using a pore distribution measuring device in accordance with JIS Z 8831-2 "Pore size distribution and pore characteristics of powders (solids) Part 2: Measurement method for mesopores and macropores by gas adsorption".

[0032] <<density>> The density of the aerogel composite is 0.01 g / cm³. 3 More than 0.02kg / m 3 More than 0.05kg / m 3 More than 0.10g / cm 3 Above, or 0.20 g / cm³ 3 Preferably, it should be 2.0 g / cm³ or more, and also 2.0 g / cm³. 3 Below 1.0g / cm 3 Below 0.80g / cm 3 Below 0.60kg / m 3 Below 0.40g / cm 3 The following, or 0.30 g / cm³ 3 The following is preferable. When the density of the aerogel composite is within this range, it is easier to obtain excellent thermal insulation properties.

[0033] <<Thermal conductivity>> The thermal conductivity of the aerogel composite is preferably less than 0.0160 W / m·K, 0.0157 W / m·K or less, or 0.0155 W / m·K or less. When the thermal conductivity of the aerogel composite is within this range, it performs sufficiently as an insulating material and can be applied to various uses.

[0034] The thermal conductivity shall be measured using a thermal conductivity measuring device (HC-72, manufactured by Eiko Seiki Co., Ltd.) in accordance with JIS A1412-2:1999 "Method for measuring the thermal resistance and thermal conductivity of thermal insulating materials - Part 2: Heat flow meter method (HFM method)".

[0035] <<<Manufacturing method>>> The aerogel composite relating to this disclosure can be manufactured, for example, by carrying out the following steps. (1) Sol preparation step to prepare a sol solution (2) Filling process in which a sol solution is filled into a porous substrate (3) Gel preparation step of gelling the sol solution in the porous substrate to prepare a wet gel (4) Solvent replacement step of replacing the water in the wet gel in the porous substrate with a non-aqueous solvent (5) Hydrophobization process to hydrophobize the surface of the wet gel in the porous substrate (6) Drying process to dry the wet gel in the porous substrate and prepare the aerogel

[0036] The method for producing an aerogel composite according to this disclosure may include a processing step of shaping the obtained silica aerogel composite into a different shape.

[0037] These processes may be carried out continuously or intermittently, or multiple processes may be carried out simultaneously.

[0038] The following describes each step in order. While the following details the manufacturing method for silica aerogel composites, composites containing aerogels other than silica aerogel can also be manufactured using the same method, except for changes in the raw materials.

[0039] <<Sol Preparation Process>> The sol preparation process involves adding various raw materials, including the main component (silica raw material), to a predetermined solvent and stirring to prepare a sol solution.

[0040] <Main ingredient> The main component is not particularly limited as long as it is a component that serves as a raw material for silica aerogel; for example, alkali metal silicates and alkoxysilanes can be cited.

[0041] Examples of alkali metal silicates include potassium silicate and sodium silicate. For example, sodium silicate is represented by the molecular formula Na2O·nSiO2·mH2O. The coefficient n is the molar ratio of SiO2·Na2O, and the coefficient m is the molar ratio of H2O to Na2O. The relationship between the mass ratio and molar ratio of the SiO2 and Na2O components is shown in Equation 1 below. (Equation 1) Mole ratio = (a / b) × 1.032 In Equation 1, a is the mass of SiO2 and b is the mass of Na2O. The constant 1.032 is the ratio of the molecular weight of SiO2 to the molecular weight of Na2O. Generally, the molar ratio (n value) of commercially available sodium silicate is 0.5 to 5.0. Sodium silicate can have any structure represented by Na2O·nSiO2, and the n value is not particularly limited. An n value of 0.5 to 5.0 is preferred for sodium silicate because it is readily available, but it may also be outside the range of 0.5 to 5.0, which is not generally manufactured. Sodium silicate can be used as an aqueous solution by dissolving it in water, for example, before mixing it with other raw materials. In that case, if the n value is less than 1, it is crystalline and does not dissolve easily in water, so a value of 1.0 to 5.0, which dissolves easily in water, is more preferred.

[0042] The alkoxysilane is not particularly limited, and difunctional, trifunctional, or tetrafunctional alkoxysilanes can be used individually or in combination. Examples of difunctional alkoxysilanes include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldiethoxysilane, diphenyldimethoxysilane, methylphenyldiethoxysilane, methylphenyldimethoxysilane, diethyldiethoxysilane, and diethyldimethoxysilane. Examples of trifunctional alkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane. Examples of tetrafunctional alkoxysilanes include tetramethoxysilane and tetraethoxysilane. In addition, bistrimethylsilylmethane, bistrimethylsilylethane, bistrimethylsilylhexane, vinyltrimethoxysilane, etc. can be used as alkoxysilanes. Furthermore, partial hydrolysates of alkoxysilanes may be used as raw materials.

[0043] <Solvent> Examples of solvents include water, alcohols (methanol, ethanol, isopropanol, tert-butanol, etc.), aprotic polar organic solvents (N,N-dimethylformamide, dimethyl sulfoxide, N,N-dimethylacetamide, etc.), hydrocarbons (n-hexane, heptane, etc.), fluorine-containing solvents (2H,3H-decafluoropentane, 1,1,2,2,3,3,4-heptafluorocyclopentane, etc.), and mixtures thereof. When alkoxysilane is used as the main agent, the hydrolysis and polymerization of the alkoxysilane are preferably carried out in the presence of water, and more preferably using a mixture of water and an organic solvent that is compatible with water and dissolves the alkoxysilane (this allows the hydrolysis and polymerization steps to be carried out consecutively). Here, the solvent that is compatible with water and dissolves the alkoxysilane is not particularly limited, and examples include alcohols such as methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-butanol, and t-butanol, as well as acetone and N,N-dimethylformamide. One of these may be used alone, or two or more may be used in combination.

[0044] <Surfactants> Surfactants may be added as various raw materials other than the main component. Surfactants contribute to the formation of the bulk portion and pore portion that constitute the aerogel in the gel preparation process described later. Examples of surfactants include nonionic surfactants and ionic surfactants (e.g., cationic surfactants, anionic surfactants, and zwionic surfactants).

[0045] <<Filling process>> The filling process is the process of filling a porous substrate with a sol solution.

[0046] The filling process can be carried out, for example, by impregnating a porous substrate with a sol solution. In this case, the impregnation time and other factors should be adjusted as appropriate so that the sol solution is sufficiently filled into the porous substrate. Furthermore, vibration may be applied to the sol solution to promote the filling of the porous substrate with the sol solution.

[0047] <<Gel Preparation Process>> The gel preparation step is a step of gelling a sol solution filled in a porous substrate, that is, a step of obtaining a gel composite in which a wet gel is filled in a porous substrate.

[0048] The gel preparation step can be carried out, for example, by adding a catalyst to the sol solution obtained in the sol preparation step.

[0049] Specific examples of basic catalysts include ammonia; tetraalkylammonium hydroxides such as tetramethylammonium hydroxide (TMAH); amines such as trimethylamine; alkali hydroxides such as sodium hydroxide; alkali metal carbonates such as sodium carbonate and sodium bicarbonate; and alkali metal silicates. Examples of acidic catalysts include hydrochloric acid, citric acid, nitric acid, sulfuric acid, and ammonium fluoride. Of these, ammonia, tetraalkylammonium hydroxides, or amines are preferred because they do not contain metal elements and do not require washing with water, with ammonia being particularly preferred.

[0050] The amount of catalyst is not particularly limited, as long as it is sufficient to adequately gel the sol solution.

[0051] In this process, a catalyst may be added to the sol solution in advance during the sol preparation or filling process. In this case, for example, the filling process can be completed before the sol solution gels, or an inactivated catalyst can be included in the sol solution and the catalyst can be activated after the filling process is completed, thereby obtaining a gel composite in which a wet gel is filled into a porous substrate.

[0052] The gel preparation process is not limited to adding a catalyst to a sol solution. For example, the gel preparation process may involve heating the sol solution to a high temperature to carry out hydrolysis or condensation polymerization.

[0053] The gel preparation step may include a step of forming a W / O emulsion in order to prepare a spherical aerogel. Specifically, this step is to disperse an aqueous sol solution in a hydrophobic solvent to form a W / O emulsion. In other words, it is a step of forming an emulsion using an aqueous sol solution as the dispersion phase and a hydrophobic solvent as the dispersion medium.

[0054] By forming such a W / O emulsion, the dispersed sol solution becomes spherical due to surface tension, etc. In this state, a spherical gel can be obtained by gelling the sol solution dispersed in the hydrophobic solvent in this spherical shape. Here, it is preferable to add a surfactant when forming the W / O emulsion. Any of anionic surfactants, cationic surfactants, or nonionic surfactants can be used.

[0055] <<Solvent Replacement Process>> The solvent replacement step is a process in which water (or water and organic solvent) on the surface and inside the gel is replaced with a non-aqueous solvent in order to suppress shrinkage of the gel (wet gel) during the drying process.

[0056] A non-aqueous solvent is a solvent other than water, preferably a polar solvent, and more preferably a solvent that is compatible with water. Specific examples include methanol, ethanol, n-propanol, isopropanol, 1-butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, xylene, 1,2-dimethoxyethane, acetonitrile, hexane, toluene, diethyl ether, chloroform, ethyl acetate, tetrahydrofuran, methylene chloride, N,N-dimethylformamide, dimethyl sulfoxide, perfluorohexane, perfluorooctane, fluorinated solvents such as methyl nonafluorobutyl ether, etc. Non-aqueous solvents may be used alone or in combination of two or more types.

[0057] The solvent replacement process may be performed once or multiple times. From the viewpoint of environmental impact, workability, and cost reduction, one solvent replacement is preferable. If multiple solvent replacements are performed, different solvents may be used in each replacement. For example, an organic solvent with a surface tension (hereinafter referred to as ST) of 45 mN / m or less at 20°C may be used as the solvent immediately before the drying process. Examples of such organic solvents include dimethyl sulfoxide (ST: 43.5 mN / m), cyclohexane (ST: 25.2 mN / m), isopropanol (ST: 21 mN / m), heptane (ST: 20.2 mN / m), pentane (ST: 15.5 mN / m), ethanol (ST: 22.4 mN / m), methanol (ST: 22.6 mN / m), perfluorohexane (ST: 12 mN / m), perfluorooctane (ST: 15 mN / m), methyl nonafluorobutyl ether (ST: 13.6 mN / m), and other fluorinated solvents.

[0058] The amount of solvent used in each solvent replacement step is, for example, between 2 and 1000 times the volume of the gel complex. The solvent replacement method may be total replacement, partial replacement, or cyclic replacement.

[0059] In the method for producing the aerogel composite according to this disclosure, a dehydrating agent is used in one, multiple, or all of the aforementioned steps. That is, solvent substitution is performed in a non-aqueous solvent containing a dehydrating agent.

[0060] The dehydrating agent is not particularly limited as long as it can dehydrate water from the solvent. The amount of water absorbed by the dehydrating agent is, for example, a component that can absorb 0.01g or more, 0.05g or more, 0.10g or more, 0.15g or more, or 0.20g or more of water per gram of dry mass of the dehydrating agent. The upper limit of the amount of water absorbed by the dehydrating agent is not limited in any way and can be 1000g or less, 100g or less, 50g or less, 10g or less, 5g or less, 2g or less, or 1g or less per gram of dry mass of the dehydrating agent.

[0061] As a dehydrating agent, a substance capable of chemically or physically dehydrating the water contained in the wet gel is used. More specifically, at least one selected from zeolite, activated alumina, silica gel, calcium oxide, magnesium oxide, aluminum oxide, sodium sulfate, calcium sulfate, magnesium sulfate, potassium carbonate, sodium hydroxide, potassium hydroxide, and calcium chloride is used. Among these, zeolite is particularly preferred because it does not significantly affect the physical properties of the gel, is easy to separate from the system after dehydration is complete, and is easy to reuse.

[0062] Here, a zeolite capable of adsorbing molecules with an effective diameter of less than 1 nm is preferred, a zeolite capable of adsorbing molecules with an effective diameter of less than 0.5 nm is more preferred, a zeolite capable of adsorbing molecules with an effective diameter of less than 0.4 nm is even more preferred, and a zeolite capable of adsorbing molecules with an effective diameter of less than 0.3 nm is most preferred.

[0063] The shape of the dehydrating agent is not particularly limited and can be in the form of a powder, pellet, sphere, or cartridge.

[0064] The amount of dehydrating agent used (dry mass) is preferably 2.5 times or more, 5.0 times or more, 7.5 times or more, 10.0 times or more, 12.5 times or more, 15.0 times or more, 17.5 times or more, 20.0 times or more, 22.5 times or more, 25.0 times or more, 27.5 times or more, 30.0 times or more, 32.5 times or more, 35.0 times or more, 37.5 times or more, 40.0 times or more, 42.5 times or more, 45.0 times or more, 47.5 times or more, or 50.0 times or more, based on the amount of water (mass) contained in the gel or gel complex. Furthermore, there is no particular limit to the amount of dehydrating agent used (dry mass), for example, 1000.0 times or less, 500.0 times or less, 100.0 times or less, 50.0 times or less, 40.0 times or less, 30.0 times or less, 25.0 times or less, 20.0 times or less, 15.0 times or less, 10.0 times or less, etc.

[0065] Thus, by performing a solvent replacement process using a dehydrating agent, moisture is more easily removed from inside the porous substrate than in a normal solvent replacement process without a dehydrating agent. As a result, the hydrophobicization process described later is less likely to be inhibited by moisture, and a silica aerogel composite with a high degree of hydrophobicity can be obtained.

[0066] The degree of hydrophobicity of the silica aerogel composite can be increased by changing the type of dehydrating agent used in the solvent replacement process, increasing the amount of dehydrating agent used, or increasing the application time of the dehydrating agent (or the number of times the solvent replacement process is performed).

[0067] Furthermore, some of the dehydrating agents used in the solvent replacement process can be regenerated by drying them through heating or other means. Such dehydrating agents are preferably reused after regeneration. Similarly, non-aqueous solvents used in the solvent replacement process are also preferably reused.

[0068] <<Hydrophobicization Process>> The hydrophobicization process involves hydrophobicizing the surface of the aerogel with a hydrophobic agent (for example, a silylate or functional silane) to prevent dehydration condensation and shrinkage of hydroxyl groups on the inner wall of the gel during drying.

[0069] Examples of functional silanes include a group of silicon compounds composed of chlorosilanes, alkoxysilanes, and silazanes.

[0070] When solvent substitution using a dehydrating agent is performed during the dehydration process, the action of the hydrophobic agent is not inhibited, and a highly hydrophobic aerogel is formed. Furthermore, such a highly hydrophobic aerogel exhibits excellent thermal insulation properties.

[0071] <<Drying process>> The drying process involves drying the gel to obtain silica aerogel. The drying method is not particularly limited and can include supercritical drying, atmospheric pressure drying, freeze-drying, etc. Of these, the manufacturing method described here is particularly suitable when using supercritical drying.

[0072] <<<Usage>>> The aerogel composite according to this disclosure exhibits superior thermal insulation and heat shielding performance compared to existing aerogel composites. Therefore, it can be made thinner, and even when placed in confined spaces, it can provide sufficient thermal insulation and heat shielding performance without constricting the space. For this reason, the aerogel composite according to this disclosure can be preferably used as a thermal insulation material and can be used in various fields such as building materials, industrial equipment, and electrical products.

[0073] Specific applications of the aerogel composite relating to this disclosure include, for example, wall materials, floor materials, or ceiling materials for buildings; insulation materials used by wrapping them around plant piping; insulation materials used by attaching them to thermoelectric elements to prevent heat diffusion or improve power generation efficiency; insulation materials used by assembling them into the housings of various batteries to stabilize battery performance; insulation materials for insulated boxes used to keep food, medical supplies, pharmaceuticals, etc., cool or warm; insulation materials used in freezers and refrigerators; and interior materials for vehicles such as automobiles, railway cars, aircraft, and ships (for example, ceiling materials installed inside the roof). [Examples]

[0074] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0075] <<Preparation of the aerogel composite according to Example 1>> <Sol preparation process> Tetramethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) is used as the main ingredient, and 45 moles of methanol (manufactured by Wako Pure Chemical Industries, Ltd.) and 25 moles of ion-exchanged water (electrical resistivity 1 × 10⁻¹⁶) are added per mole of the main ingredient. 10 A sol solution was prepared by mixing a Ω·cm or larger oz oz oz oz with 0.01 moles of catalyst {25% aqueous ammonia (manufactured by Wako Pure Chemical Industries, Ltd.)}.

[0076] <Filling process / Gel preparation process> The substrate (foam) shown in Table 1 was cut to a width of 300 mm and a length of 10 m, placed in a separable flask, and then the sol solution was added until the substrate was completely immersed. The mixture was left to stand under atmospheric pressure for 3 hours to obtain a foam substrate filled with wet gel.

[0077] <Solvent replacement process> A polyolefin foam filled with a wet gel and a dehydrating agent (zeolite: molecular sieve 3A) were immersed in methanol, and solvent replacement was performed for 24 hours while stirring. The water concentration in methanol at the end of the process, measured using a Hiranuma trace moisture analyzer (HIRANUMA Co., Ltd.: AQ-2200A) in accordance with JIS K 0068:2001 "Method for measuring moisture content of chemical products," was 0.07%.

[0078] <Hydrophobicization process> To hydrophobize the gel surface within the foamed substrate after solvent replacement, the substrate was immersed in a methanol solution of hexamethyldisilazane (20% by mass) and subjected to a hydrophobic treatment while stirring for 24 hours.

[0079] <Drying process> A substrate with a hydrophobic gel surface was impregnated in carbon dioxide at 80°C and 20 MPa, and supercritical drying was performed for 12 hours to obtain the aerogel composite of Example 1.

[0080] <<Preparation of aerogel composite according to Example 2-4>> Except for using the substrates shown in Table 1, an aerogel composite was prepared in the same manner as in Example 1 to obtain the aerogel composites according to Examples 2-4.

[0081] <<Preparation of the aerogel composite according to Comparative Example 1>> An aerogel composite was produced in the same manner as in Example 1, except that a dehydrating agent was not used in the hydrophobicization process and solvent substitution was performed four times, to obtain the aerogel composite according to Comparative Example 1.

[0082] <<Preparation of the aerogel composite according to Comparative Example 2>> An aerogel composite was manufactured in the same manner as in Comparative Example 1, except that the substrate used was as shown in Table 2, to obtain the aerogel composite according to Comparative Example 2.

[0083] <<Measurement / Evaluation>> The density, degree of hydrophobicity, and thermal conductivity of the aerogel composites in each example and comparative example were measured. The measurement results are shown in Tables 1 and 2.

[0084] [Table 1]

[0085] [Table 2]

Claims

1. It comprises a porous substrate and an aerogel filled in the voids inside the porous substrate, BET specific surface area based on water vapor adsorption method SA Ｍ The BET specific surface area based on the nitrogen gas adsorption method is SA Ｎ When that happens, [SA Ｎ / SA Ｍ An aerogel composite characterized by having a degree of hydrophobicity of 10.0 or higher, as indicated by [ ].

2. The aerogel composite according to claim 1, wherein the aerogel is a silica aerogel.

3. The aerogel composite according to claim 1 or 2, wherein the thermal conductivity is less than 0.0160 W / m·K.

4. The aerogel composite according to claim 1 or 2, wherein the porous substrate is a foam.

5. An aerogel composite according to claim 1 or 2, which is an insulating material.

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