Method of making aerogel composites and aerogel composites

Abstract

The present invention relates to a method of manufacturing an aerogel composite and an aerogel composite manufactured thereby, wherein the method comprises impregnating catalytic silica sol into a fiber mat at a volume ratio (catalytic silica sol: fiber mat) of 0.1 to 1:1, and then performing gelation thereon (S10).

Description

Technical Field

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2021-0043328 filed in the Korean Intellectual Property Office on April 2, 2021, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] The present invention relates to a method for producing an aerogel composite and an aerogel composite produced thereby, which can be used as a sound absorbing material with improved sound absorption. Background Art

[0005] Glass fiber mats or polymer mats, primarily used as sound absorbing materials, are widely used as insulation materials due to their excellent thermal insulation and sound absorption properties. However, glass fiber mats or polymer mats contain fibers with diameters ranging from several micrometers to tens of micrometers (μm) and macropores in between. Therefore, there are limits to improving thermal insulation and sound absorption properties except by increasing the thickness of the mat.

[0006] Korean Patent Publication No. 10-1391098 discloses a sound-absorbing panel made of a nonwoven fabric of glass fiber, cellulose fiber, and organic synthetic fiber, intended to improve the sound absorption performance of a glass fiber mat. However, this panel has relatively large average pore sizes of approximately 10 μm to 50 μm, making it difficult to achieve substantial improvements in thermal insulation performance. Furthermore, it is difficult to expect improvements in sound absorption performance in the high-frequency range above 2000 Hz, particularly above 2500 Hz.

[0007] Prior art literature

[0008] Patent Literature

[0009] (Patent Document 1) KR10-1391098B1 Summary of the Invention

[0010] Technical issues

[0011] One aspect of the present invention provides a method of manufacturing an aerogel composite and an aerogel composite manufactured thereby, which can be used as a sound absorbing material because the aerogel composite has improved sound absorption rate and can also ensure heat insulation performance.

[0012] Technical Solution

[0013] One aspect of the present invention provides a method of making an aerogel composite, and an aerogel composite made thereby.

[0014] (1) The present invention provides a method for manufacturing an aerogel composite, comprising: impregnating a catalytic silica sol into a fiber mat at a volume ratio of 0.1 to 1:1 (catalytic silica sol: fiber mat), and then performing gelation thereon in step S10.

[0015] (2) In the above (1), the present invention provides a method for manufacturing an aerogel composite, wherein step S10 is performed by impregnating the catalytic silica sol into the fiber mat at a volume ratio of 0.1 to 0.9:1 (catalytic silica sol: fiber mat), and then performing gelation thereon.

[0016] (3) In the above (1) or (2), the present invention provides a method for manufacturing an aerogel composite, wherein a catalytic silica sol is prepared by the following steps: step S1 of mixing a silica precursor, an organic solvent and an aqueous solvent to prepare a silica precursor composition, step S2 of mixing an organic solvent, a base catalyst and a hydrophobizing agent to prepare a catalyst composition, and step S3 of mixing the silica precursor composition and the catalyst composition to prepare the catalytic silica sol.

[0017] (4) In the above (3), the present invention provides a method for manufacturing an aerogel composite, wherein the silica concentration of the silica precursor composition prepared in step S1 is 10 kg / m 3 Up to 100kg / m 3 .

[0018] (5) In the above (3) or (4), the present invention provides a method for manufacturing an aerogel composite, wherein the silica concentration of the silica precursor composition prepared in step S1 is 40 kg / m 3 Up to 70kg / m 3 .

[0019] (6) In any one of the above (1) to (5), the present invention provides a method for manufacturing an aerogel composite, the method comprising a step S20 of ripening the wet gel composite gelled in step S10 and a step S30 of drying the wet gel composite ripened in step S20 to obtain an aerogel composite.

[0020] (7) In the above (6), the present invention provides a method for manufacturing an aerogel composite, wherein the aerogel composite obtained in step S30 has pores with a pore diameter of 2 nm to 50 nm.

[0021] (8) In any one of the above (1) to (7), the present invention provides a method for producing an aerogel composite, wherein the fiber mat is a glass fiber mat.

[0022] (9) In any one of the above (1) to (8), the present invention provides a method for producing an aerogel composite, wherein the fiber mat has pores with a pore size of 100 μm to 1000 μm.

[0023] (10) The present invention provides an aerogel composite comprising a fiber mat and aerogel formed inside and on the surface of the fiber mat, wherein the overall average sound absorption coefficient is greater than 0.41, and the overall average sound absorption coefficient is the average value of the sound absorption coefficient at each frequency obtained by digitizing the 1 / 3 octave band of the sound absorption rate measured in the frequency range of 50 Hz to 6400 Hz using an impedance tube P-S40-20.

[0024] (11) In the above (10), the present invention provides an aerogel composite, wherein the high-frequency average sound absorption coefficient of the aerogel composite is greater than 0.35, and the high-frequency average sound absorption coefficient is the average value of the sound absorption coefficient at each frequency obtained by digitizing the 1 / 3 octave band of the sound absorption rate measured in the frequency range of 2500 Hz to 6400 Hz using an impedance tube P-S40-20.

[0025] (12) In the above (10) or (11), the present invention provides an aerogel composite, wherein the room temperature thermal conductivity of the aerogel composite is less than 30.0 mW / mK.

[0026] Beneficial effects

[0027] The aerogel composite manufactured by the method for manufacturing an aerogel composite of the present invention has reduced macropores and increased mesopores in the fiber mat, thereby having the effects of improving sound absorption and heat insulation performance.

[0028] The aerogel composite of the present invention has excellent sound absorption and heat insulation properties, and therefore can be used as a sound absorption material.

[0029] Furthermore, the aerogel composite of the present invention has particularly good sound absorption properties in the high-frequency range. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The sound absorption coefficients at each frequency of the aerogel composites manufactured in Examples 1 to 3 and the glass fiber mat of Comparative Example 1 are shown, which are calculated by digitizing the 1 / 3 octave band of the sound absorption rate measured in the frequency range of 50 Hz to 6400 Hz using an impedance tube P-S40-20. DETAILED DESCRIPTION

[0031] Hereinafter, the present invention will be described in more detail to facilitate understanding of the present invention.

[0032] It should be understood that the words or terms used in the description and claims of the present invention should not be interpreted as having the meanings defined in commonly used dictionaries. It should be further understood that based on the principle that the inventor can appropriately define the meanings of words or terms in order to best explain the present invention, the words or terms should be interpreted as having a meaning consistent with the background of the relevant technology and the technical concept of the present invention.

[0033] In the present invention, the terms "mesopores" and "macroporous" refer to pores having pore sizes classified according to IUPAC recommendations, wherein mesopores refer to pores with a pore size of 2 nm to 50 nm, and macropores refer to pores with a pore size greater than 50 nm.

[0034] The present invention provides a method for manufacturing an aerogel composite. The aerogel composite manufactured by the method has improved sound absorption rate and can be used as a sound absorbing material.

[0035] According to one embodiment of the present invention, the method for manufacturing an aerogel composite may include: impregnating catalytic silica sol into a fiber mat at a volume ratio of 0.1 to 1:1 (catalytic silica sol: fiber mat), and then performing gelation thereon ( S10 ).

[0036] According to one embodiment of the present invention, step S10 is a step for forming an aerogel composite, which may be a step of impregnating catalytic silica sol into a fiber mat and then performing gelation thereon to form aerogel inside and on the surface of the fiber mat.

[0037] According to one embodiment of the present invention, the "impregnation" can be performed by injecting a fluid catalytic silica sol into the fiber mat, whereby the catalytic silica sol can penetrate into the pores inside the fiber mat.

[0038] According to one embodiment of the present invention, "gelation" can be performed by gelling the catalytic silica sol impregnated into the fiber mat, or by allowing the fiber mat impregnated with the catalytic silica sol to stand. Gelation and impregnation can be performed simultaneously.

[0039] According to one embodiment of the present invention, step S10 may be performed by introducing the catalytic silica sol and the fiber mat into a reaction vessel, or may be performed by introducing the catalytic silica sol onto the fiber mat moving on a conveyor belt according to a roll-to-roll process.

[0040] According to one embodiment of the present invention, when step S10 is performed by introducing a catalytic silica sol and a fiber mat into a reaction vessel, the order in which the catalytic silica sol and the fiber mat are introduced into the reaction vessel is not particularly limited. As specific examples, the impregnation in step S10 can be performed by any of the following methods: introducing the fiber mat into the reaction vessel and then introducing the catalytic silica sol therein; introducing the catalytic silica sol into the reaction vessel and then introducing the fiber mat therein; or introducing the fiber mat into the reaction vessel simultaneously with the catalytic silica sol. Of these methods, the method of introducing the fiber mat and then introducing the catalytic silica sol therein is preferred in terms of inducing more uniform impregnation.

[0041] According to one embodiment of the present invention, as described above, step S10 can be performed by impregnating the catalytic silica sol into the fiber mat at a volume ratio of 0.1 to 1:1 (catalytic silica sol: fiber mat), and then performing gelation thereon. As described above, by controlling the volume ratio of the catalytic silica sol impregnated into the fiber mat, a gel is formed within the fiber mat, thereby increasing the mesopores of the fiber mat while reducing the macropores, thereby improving the sound absorption performance of the aerogel composite and improving the thermal insulation performance of the aerogel formed within and on the surface of the fiber mat.

[0042] According to one embodiment of the present invention, in order to improve thermal insulation performance exceeding a predetermined level compared to a fiber mat and further improve sound absorption performance, particularly in the high-frequency range (referring to above 2500 Hz), the catalytic silica sol can be impregnated into the fiber mat at a volume ratio of 0.1, 0.2, or 0.3 or higher, or at a volume ratio of 1.0, 0.9, 0.8 or less, or 0.7 or less. As a specific example, step S10 can be performed by impregnating the fiber mat with the catalytic silica sol at a volume ratio (catalytic silica sol:fiber mat) of 0.1 to 0.9:1, 0.2 to 0.8, or 0.3 to 0.7, and then performing gelation thereon. In this case, thermal insulation performance exceeding a predetermined level compared to the fiber mat can be ensured, while high-frequency sound absorption performance can be further improved.

[0043] According to one embodiment of the present invention, the catalytic silica sol can be prepared by the following steps: step S1 of mixing a silica precursor, an organic solvent and an aqueous solvent to prepare a silica precursor composition, step S2 of mixing an organic solvent, a base catalyst and a hydrophobizing agent to prepare a catalyst composition, and step S3 of mixing the silica precursor composition and the catalyst composition to prepare the catalytic silica sol.

[0044] According to one embodiment of the present invention, the silica precursor composition prepared in step S1 may be a silica precursor composition for ultimately manufacturing silica aerogel by mixing with the catalyst composition prepared in step S2 to catalyze the gelation reaction of the silica sol prepared in step S3.

[0045] According to one embodiment of the present invention, the silica precursor of step S1 is used to make the aerogel manufactured by gelation in step S10 contain silica, and can be one or more selected from the group consisting of: tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), methyl triethyl orthosilicate, dimethyl diethyl orthosilicate, tetrapropyl orthosilicate, tetraisopropyl orthosilicate, tetrabutyl orthosilicate, tetra-sec-butyl orthosilicate, tetra-tert-butyl orthosilicate, tetrahexyl orthosilicate, tetracyclohexyl orthosilicate and tetra(dodecyl) orthosilicate, or a pre-hydrolyzate of the above compounds can be used. Here, when the pre-hydrolyzate is used, it is not necessary to add acid, the process of hydrolyzing the silica precursor can be shortened or omitted, and the effect of surface modification can be promoted. As a specific example, the silica precursor may be prehydrolyzed polyethyl silicate (HTEOS), which is a prehydrolyzed polyethyl silicate oligomer having a wide molecular weight distribution and can be easily applied according to the user's reaction conditions because physical properties such as gelation time can be controlled when an oligomer form is synthesized from tetraethyl orthosilicate (TEOS) by varying the degree of prehydrolysis (hydration degree).

[0046] According to one embodiment of the present invention, the organic solvent in step S1 can be an alcohol. The alcohol can be a monohydric alcohol such as methanol, ethanol, isopropanol, and butanol; or a polyhydric alcohol such as glycerol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and sorbitol, and any one or a mixture of two or more thereof can be used. Among them, when considering its miscibility with aqueous solvents and aerogels, the alcohol can be a monohydric alcohol having 1 to 6 carbon atoms, such as methanol, ethanol, isopropanol, and butanol, and as a specific example, it can be ethanol.

[0047] According to one embodiment of the present invention, the aqueous solvent in step S1 may be water, and as a specific example, may be distilled water.

[0048] According to one embodiment of the present invention, the silica concentration of the silica precursor composition prepared in step S1 may be 10 kg / m 3 Up to 100kg / m 3The silica concentration is the concentration of silica contained in the silica precursor relative to the silica precursor composition. The silica concentration can be adjusted by adjusting the composition of the silica precursor, the organic solvent, and the aqueous solvent. As a specific example, the silica concentration of the silica precursor composition prepared in step S1 can be 20 kg / m 3 Up to 80kg / m 3 、30kg / m 3 Up to 70kg / m 3 、30kg / m 3 Up to 60kg / m 3 or 35kg / m 3 Up to 45kg / m 3 Within this range, since aerogel is formed in the fiber mat, the mesopores of the fiber mat can be increased while the macropores are reduced, thereby improving the sound absorption performance of the aerogel composite and improving the thermal insulation performance of the aerogel formed inside and on the surface of the fiber mat.

[0049] According to one embodiment of the present invention, step S1 can be performed by mixing a silica precursor, an organic solvent, and an aqueous solvent in a weight ratio of 1:0.1 to 1.5:0.1 to 0.5, 1:0.5 to 1.5:0.1 to 0.4, or 1:0.5 to 1.2:0.1 to 0.3 to satisfy the silica concentration of the silica precursor composition prepared in step S1.

[0050] According to one embodiment of the present invention, the catalyst composition prepared in step S2 may be a catalyst composition for inducing a gelation reaction of the catalytic silica sol prepared in step S3 by mixing with the silica precursor composition prepared in step S1 to ultimately produce silica aerogel.

[0051] According to one embodiment of the present invention, the organic solvent in step S2 can be an alcohol. The alcohol can be a monohydric alcohol such as methanol, ethanol, isopropanol, and butanol; or a polyhydric alcohol such as glycerol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and sorbitol, and any one or a mixture of two or more thereof can be used. When considering the miscibility with the aqueous solvent and the aerogel, the alcohol can be a monohydric alcohol having 1 to 6 carbon atoms, such as methanol, ethanol, isopropanol, and butanol, and as a specific example, can be ethanol.

[0052] According to one embodiment of the present invention, the base catalyst in step S2 can be a base catalyst that allows the formation of pH conditions to achieve the gelation of catalytic silica sol, and the base catalyst can be an inorganic base such as sodium hydroxide and potassium hydroxide, or an organic base such as ammonium hydroxide.

[0053] According to one embodiment of the present invention, the organic base may be one or more selected from the group consisting of ammonium hydroxide (NH4OH), tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), methylamine, ethylamine, isopropylamine, monoisopropylamine, diethylamine, diisopropylamine, dibutylamine, trimethylamine, triethylamine, triisopropylamine, tributylamine, choline, monoethanolamine, diethanolamine, 2-aminoethanol, 2-(ethylamino)ethanol, 2-(methylamino)ethanol, N-methyldiethanolamine, dimethylaminoethanol, diethylaminoethanol, aminotriethanol, 2-(2-aminoethoxy)ethanol, 1-amino-2-propanol, triethanolamine, monopropanolamine or dibutanolamine, and as a specific example, the organic base may be ammonium hydroxide (NH4OH).

[0054] According to one embodiment of the present invention, the hydrophobizing agent of step S2 can be an alkylsilane compound, and as a specific example, the hydrophobizing agent can be an alkylsilane compound comprising an alkyl group induced to be hydrophobized and a silane functional group capable of reacting with "-Si-O-" functional group of a wet gel. The more specific examples of the hydrophobizing agent can include one or more selected from the group consisting of: trimethylethoxysilane (TMES), trimethylsilanol (TMS), trimethylchlorosilane (TMCS), methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), dimethyldiethoxysilane (DMDEOS), ethyltriethoxysilane and phenyltriethoxysilane. As a co-precursor, the alkylsilane compound can participate in the gelation reaction of a silicon dioxide precursor together, and therefore the wet gel composite formed by gelation can be made hydrophobic. That is, the alkylsilane composite can be gelated with a silicon dioxide precursor in the gelation process of step S10. Furthermore, the alkylsilane compounds trapped in the gel that are not gelled can form an alkyl-Si-O-Si network during the ripening process and thus can hydrophobize the wet gel composite.

[0055] According to one embodiment of the present invention, step S2 may be performed by mixing the organic solvent, the base catalyst, and the hydrophobizing agent in a weight ratio of 1:0.01 to 0.1:0.1 to 0.5, 1:0.02 to 0.08:0.1 to 0.3, or 1:0.04 to 0.06:0.1 to 0.2.

[0056] According to one embodiment of the present invention, step S3 is a step for preparing the catalytic silica sol impregnated and gelled into the fiber mat in step S10, and step S3 can be performed by mixing the silica precursor composition prepared in step S1 and the catalyst composition prepared in step S2.

[0057] According to one embodiment of the present application, step S3 can be performed by mixing the silica precursor composition and the catalyst composition at a volume ratio of 1:0.1 to 10.0, 1:0.5 to 5.0, 1:0.7 to 2.0, or 1:0.8 to 1.2.

[0058] According to one embodiment of the present application, the aerogel composite manufactured through the impregnation and gelation of step S10 can be obtained in the form of a wet gel composite in which the solvent is included in the gelation. Therefore, to obtain a dry aerogel composite, the method of manufacturing an aerogel composite can further include a step S20 of ripening the wet gel composite gelated in step S10, and a step S30 of drying the wet gel composite ripened in step S20 to obtain an aerogel composite.

[0059] According to one embodiment of the present application, step S20 is a ripening step in which the gelated wet gel composite is left to stand at a suitable temperature to allow the chemical change to be fully achieved, and since the network structure formed through the gelation can be more firmly formed, the mechanical stability of the aerogel composite can be improved.

[0060] According to one embodiment of the present application, step S20 can be performed by leaving the gelated wet gel composite to stand at a suitable temperature, or as another example, step S20 can be performed by adding a solution in which an alkali catalyst such as sodium hydroxide (NaOH), potassium hydroxide (KOH), ammonium hydroxide (NH4OH), triethylamine, or pyridine, etc. is diluted to a concentration of 1 to 10% in an organic solvent in the presence of the wet gel mat composite. In this case, the Si-O-Si bond in the aerogel is induced to the maximum extent, so that the network structure of the silica gel is more firmly formed, thereby having an effect of facilitating the maintenance of the pore structure in the drying process subsequently performed. At this time, the organic solvent can be the alcohol described above, and specifically, can include ethanol.

[0061] According to one embodiment of the present application, step S20 can be performed by leaving the gelated wet gel composite to stand at a temperature of 30°C to 70°C, 40°C to 70°C, or 50°C to 70°C for 1 hour to 30 hours, 10 hours to 30 hours, or 20 hours to 25 hours to strengthen the pore structure, and within the above ranges, it is possible to prevent the increase in manufacturing cost by preventing the loss of the solvent due to evaporation while preventing the decrease in productivity.

[0062] According to one embodiment of the present application, step S20 can be performed in a separate reaction vessel after recovering the gelated silica wet gel composite, or can be performed inside the reaction vessel in which step S10 is performed.

[0063] According to one embodiment of the present invention, step S30 is a step of drying the wet gel composite matured in step S20 to obtain an aerogel composite, thereby obtaining a dried aerogel composite, and the drying step can be performed by supercritical drying or normal pressure drying, thereby removing the solvent while maintaining the pore structure of the matured gel.

[0064] According to one embodiment of the present invention, supercritical drying can be carried out using supercritical carbon dioxide. Carbon dioxide (CO2) is a gaseous state at room temperature and normal pressure. However, when temperature and pressure exceed the predetermined temperature and pressure limits known as the supercritical point, no evaporation process occurs, causing carbon dioxide to become a critical state in which gas and liquid cannot be distinguished. Carbon dioxide in a critical state is referred to as supercritical carbon dioxide. Supercritical carbon dioxide has a molecular density close to that of a liquid, but has a low viscosity, thereby having properties close to those of a gas. Therefore, supercritical carbon dioxide has a high diffusion rate and high thermal conductivity, making its drying efficiency high and the drying process time can be shortened. Supercritical drying is carried out in the following manner: the slaking wet gel is imported into a supercritical drying reactor, liquid carbon dioxide is loaded therein, and a solvent replacement process is then carried out in which the alcohol solvent in the wet gel is replaced with carbon dioxide. The temperature is then raised to 40°C to 80°C, 50°C to 80°C, or 60°C to 80°C at a heating rate of 0.1°C / min to 1°C / min, and then maintained at a pressure greater than or equal to the pressure at which carbon dioxide becomes supercritical, specifically 100 bar to 150 bar, to maintain the carbon dioxide (CO2) in a supercritical state for a predetermined time, specifically 20 minutes to 1 hour. Typically, carbon dioxide becomes supercritical at a temperature of 31°C and a pressure of 73.8 bar. After maintaining the carbon dioxide at the predetermined temperature and pressure to maintain the supercritical state for 2 to 12 hours, more specifically 2 to 6 hours, the pressure is typically reduced to complete the supercritical drying process, thereby obtaining an aerogel composite. At this point, the organic solvent or other solvent removed from the wet gel composite by supercritical drying can be separately recovered by a separator connected to the supercritical reactor.

[0065] According to one embodiment of the present invention, atmospheric drying can be performed by conventional methods, such as hot air drying or infrared (IR) drying at a temperature of 70° C. to 200° C. and atmospheric pressure (1±0.3 atm).

[0066] According to one embodiment of the present invention, the aerogel composite obtained in step S30 may contain pores with a pore size of 2 nm to 50 nm, and as a specific example, the volume ratio of pores with a pore size of 2 nm to 50 nm may be greater than the volume ratio of pores with a pore size of 100 μm to 1000 μm, and since aerogel is formed inside the fiber mat, the mesopores of the fiber mat can be increased while the macropores of the fiber mat are reduced, thereby improving the sound absorption performance of the aerogel composite and improving the thermal insulation performance of the aerogel formed inside and on the surface of the fiber mat.

[0067] According to one embodiment of the present invention, the fiber mat may be a glass fiber mat that can be used as a sound absorbing material, and as a specific example, the fiber mat may be a fiber mat formed of fibers or glass fibers having a diameter greater than 1 μm or a diameter of 1 μm to 100 μm. In addition, the fiber mat may contain pores between the fibers or glass fibers, and the pores have a pore size greater than 50 nm, specifically, a pore size of 100 μm to 1000 μm, that is, macropores.

[0068] According to the method for manufacturing an aerogel composite of the present invention, by forming an aerogel composite for a fiber mat (specifically, a glass fiber mat) that can itself be used as a sound absorbing material, the mesopores of the fiber mat can be increased while the macropores can be reduced, thereby improving both the sound absorption performance and the thermal insulation performance.

[0069] The present invention provides an aerogel composite. The aerogel composite can be manufactured by the method for manufacturing an aerogel composite, and thus the aerogel composite has improved sound absorption rate and can be used as a sound absorbing material.

[0070] According to one embodiment of the present invention, the aerogel composite includes a fiber mat and aerogel formed inside and on the surface of the fiber mat, wherein the overall average sound absorption coefficient is greater than 0.41, and the overall average sound absorption coefficient is the average value of the sound absorption coefficient of each frequency calculated by digitizing the 1 / 3 octave band of the sound absorption rate measured in the frequency range of 50 Hz to 6400 Hz using an impedance tube P-S40-20.

[0071] According to one embodiment of the present invention, the fiber mat may be the same as the fiber mat described in the method for manufacturing an aerogel composite, and the aerogel may be an aerogel formed according to the method for manufacturing an aerogel composite.

[0072] According to one embodiment of the present invention, an aerogel composite may include a fiber mat component and macropores within the fiber mat. The fiber mat component includes pores originating from the fiber mat and having a pore size of 100 to 1000 μm, formed by fibers or glass fibers having a diameter greater than 1 μm or a diameter of 1 to 100 μm. As a specific example, pores having a pore size of 2 to 50 nm formed within the pores having a pore size of 100 to 1000 μm become mesopores. As described above, when aerogel is formed within the fiber mat, the macropores are reduced while the mesopores are increased, thereby reducing the average diameter of all pores within the fiber mat, thereby improving sound absorption performance. Furthermore, due to the formation of aerogel within the fiber mat, thermal insulation performance can also be improved.

[0073] According to one embodiment of the present invention, the aerogel composite may contain pores with a pore size greater than 50 nm, originating from the fiber mat. Specifically, for example, pores with a pore size of 100 μm to 1000 μm, i.e., some macropores. However, even in this case, the volume ratio of pores with a pore size of 2 nm to 50 nm, i.e., mesopores, in the aerogel composite may be higher than the volume ratio of pores with a pore size greater than 50 nm, i.e., macropores. Furthermore, due to the formation of aerogel within the fiber mat, the mesopores of the fiber mat can be increased while the macropores are reduced, thereby improving the sound absorption performance of the aerogel composite and the thermal insulation performance of the aerogel formed within and on the surface of the fiber mat.

[0074] According to one embodiment of the present invention, the overall average sound absorption coefficient of the aerogel composite is 0.41 or more, 0.41 to 0.60, or 0.43 to 0.54, which is the average value of the sound absorption coefficient of each frequency calculated by digitizing the 1 / 3 octave band of the sound absorption rate measured in the frequency range of 50 Hz to 6400 Hz using an impedance tube P-S40-20, and when the overall average sound absorption coefficient is within this range, it can be considered that the sound absorption performance is excellent.

[0075] According to one embodiment of the present invention, the aerogel composite can have a sound absorption coefficient calculated by digitizing the 1 / 3 octave band of the sound absorption rate measured at a frequency of 2500 Hz using an impedance tube P-S40-20, which can be 0.50 or higher, 0.51 or higher, or 0.59 or higher, and can be 1.00 or lower, 0.95 or lower, or 0.91 or lower. Furthermore, to ensure sound absorption performance in the high-frequency range, the aerogel composite can have a sound absorption coefficient of 0.60 or higher, 0.65 or higher, 0.70 or higher, 0.71 or higher, or 0.82 or higher at a frequency of 2500 Hz.

[0076] According to one embodiment of the present invention, the aerogel composite may have a sound absorption coefficient calculated by digitizing the 1 / 3 octave band of the sound absorption rate measured at a frequency of 3150 Hz using an impedance tube P-S40-20, and may be 0.35 or greater, 0.39 or greater, or 0.41 or greater, and 1.00 or less, 0.95 or less, 0.90 or less, or 0.89 or less. Furthermore, to ensure sound absorption performance in the high-frequency range, the aerogel composite may have a sound absorption coefficient of 0.47 or greater, 0.52 or greater, 0.70 or greater, 0.60 or greater, 0.70 or greater, or 0.77 or greater at a frequency of 3150 Hz.

[0077] According to one embodiment of the present invention, the aerogel composite may have a sound absorption coefficient calculated by digitizing the 1 / 3 octave band of the sound absorption rate measured at a frequency of 4000 Hz using an impedance tube P-S40-20, and may be 0.28 or greater, 0.31 or greater, or 0.36 or greater, and 1.00 or less, 0.95 or less, 0.90 or less, or 0.87 or less. Furthermore, to ensure sound absorption performance in the high-frequency range, the aerogel composite may have a sound absorption coefficient of 0.37 or greater, 0.40 or greater, 0.50 or greater, 0.60 or greater, or 0.61 or greater at a frequency of 4000 Hz.

[0078] According to one embodiment of the present invention, the aerogel composite may have a sound absorption coefficient calculated by digitizing the 1 / 3 octave band of the sound absorption rate measured at a frequency of 5000 Hz using an impedance tube P-S40-20, and may be 0.25 or greater, 0.27 or greater, or 0.35 or greater, and 1.00 or less, 0.90 or less, 0.80 or less, or 0.79 or less. Furthermore, to ensure sound absorption performance in the high-frequency range, the aerogel composite may have a sound absorption coefficient of 0.52 or greater, 0.53 or greater, 0.60 or greater, 0.67 or greater, or 0.69 or greater at a frequency of 5000 Hz.

[0079] According to one embodiment of the present invention, the aerogel composite may have a sound absorption coefficient calculated by digitizing the 1 / 3 octave band of the sound absorption rate measured at a frequency of 6300 Hz using an impedance tube P-S40-20, and may be 0.25 or greater, 0.35 or greater, or 0.36 or greater, and 1.00 or less, 0.90 or less, 0.80 or less, or 0.74 or less. Furthermore, to ensure sound absorption performance in the high-frequency range, the aerogel composite may have a sound absorption coefficient of 0.43 or greater, 0.50 or greater, 0.60 or greater, 0.62 or greater, or 0.68 or greater at a frequency of 6300 Hz.

[0080] According to one embodiment of the present invention, the high-frequency average sound absorption coefficient of the aerogel composite may be 0.35 or more, 0.44 or more, or 0.48 or more, and 1.00 or less, 0.95 or less, 0.90 or less, 0.85 or less, or 0.82 or less. The high-frequency average sound absorption coefficient is the average value of the sound absorption coefficient at each frequency calculated by digitizing the 1 / 3 octave band of the sound absorption rate measured within the frequency range of 2500 Hz to 6400 Hz using an impedance tube P-S40-20. Furthermore, in order to ensure sound absorption performance within the high-frequency range, the high-frequency average sound absorption coefficient of the aerogel composite may be 0.53 or more, 0.60 or more, 0.65 or more, or 0.69 or more.

[0081] According to one embodiment of the present invention, the aerogel composite has excellent sound absorption and thermal insulation properties, and may have a room temperature thermal conductivity of 30.0 mW / mK or less, 1.0 mW / mK to 30.0 mW / mK, 10.0 mW / mK to 29.0 mW / mK, or 18.3 mW / mK to 28.8 mW / mK. When the room temperature thermal conductivity falls within this range, it is considered that the thermal insulation performance is sufficiently ensured.

[0082] Hereinafter, the embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention can be embodied in many different forms and is not limited to the embodiments described herein.

[0083] Example

[0084] Example 1

[0085] Pre-hydrolyzed TEOS (silicon dioxide content: 20 wt %, HTEOS), ethanol, and distilled water were added to a reactor and then mixed in a weight ratio of 1:0.9:0.22 to prepare a silica precursor composition. At this time, the silica concentration of the silica precursor composition was 40 kg / m 3 Meanwhile, ethanol, aqueous ammonia (concentration: 30 wt%), and trimethylethoxysilane (TMES) were added to another reactor and mixed in a weight ratio of 1:0.054:0.154 to prepare a catalyst composition. The silica precursor composition prepared above and the catalyst composition were mixed in a volume ratio of 1:1 to prepare a catalytic silica sol.

[0086] A glass fiber mat (Hyundai Fiber Co., Ltd.) containing pores with a pore size of 100 to 1000 μm was then introduced into the reaction vessel. Catalytic silica sol was impregnated at a volume ratio of 0.3:1 (catalytic silica sol:glass fiber mat) relative to the volume of the glass fiber mat. After 10 minutes, the mixture was gelled to produce a wet gel composite. The gelled wet gel composite was then left to mature in a 70°C oven for 24 hours. The matured wet gel composite was placed in a 7.2L supercritical extractor and injected with carbon dioxide (CO2). The internal temperature of the extractor was then raised to 75°C. Once the temperature reached 75°C and 150 bar, a cycle of injecting and purging CO2 at a rate of 0.5 L / min for 20 minutes, followed by a 20-minute cessation of CO2 injection, was repeated four times. While injecting and purging CO2, ethanol was recovered through the lower end of the extractor. The CO2 was then discharged over a two-hour period. After the supercritical drying is completed, a dry aerogel composite is obtained.

[0087] Example 2

[0088] The wet gel composite was prepared in the same manner as in Example 1, except that the catalytic silica sol was impregnated at a volume ratio of 0.7:1 (catalytic silica sol:glass fiber mat) relative to the volume of the glass fiber mat and then gelated thereon after 10 minutes to prepare the wet gel composite.

[0089] Example 3

[0090] The wet gel composite was prepared in the same manner as in Example 1, except that the catalytic silica sol was impregnated at a volume ratio of 1:1 (catalytic silica sol:glass fiber mat) relative to the volume of the glass fiber mat and then gelled thereon after 10 minutes.

[0091] Example 4

[0092] In addition to the above Example 1, when preparing the silica precursor composition, the silica concentration of the silica precursor composition was 50 kg / m by adjusting the weight ratio of pre-hydrolyzed TEOS (silicon dioxide content: 20 wt %, HTEOS), ethanol and distilled water. 3 The same procedure as in Example 1 was followed except that the silica precursor composition was prepared.

[0093] Example 5

[0094] The wet gel composite was prepared in the same manner as in Example 4, except that the catalytic silica sol was impregnated at a volume ratio of 0.7:1 (catalytic silica sol:glass fiber mat) relative to the volume of the glass fiber mat and then gelated thereon 10 minutes later.

[0095] Example 6

[0096] The wet gel composite was prepared in the same manner as in Example 4, except that the catalytic silica sol was impregnated at a volume ratio of 1:1 (catalytic silica sol:glass fiber mat) relative to the volume of the glass fiber mat and then gelated thereon after 10 minutes to prepare the wet gel composite.

[0097] Example 7

[0098] In addition to the above Example 1, when preparing the silica precursor composition, the silica concentration of the silica precursor composition was 70 kg / m by adjusting the weight ratio of pre-hydrolyzed TEOS (silicon dioxide content: 20 wt %, HTEOS), ethanol and distilled water. 3 The same procedure as in Example 1 was followed except that the silica precursor composition was prepared.

[0099] Example 8

[0100] The wet gel composite was prepared in the same manner as in Example 7, except that the catalytic silica sol was impregnated at a volume ratio of 0.7:1 (catalytic silica sol:glass fiber mat) relative to the volume of the glass fiber mat and then gelated thereon 10 minutes later.

[0101] Example 9

[0102] The wet gel composite was prepared in the same manner as in Example 7, except that the catalytic silica sol was impregnated at a volume ratio of 1:1 (catalytic silica sol:glass fiber mat) relative to the volume of the glass fiber mat and then gelated thereon after 10 minutes to prepare the wet gel composite.

[0103] Comparative Example 1

[0104] A glass fiber mat containing pores having a pore diameter of 100 to 1000 μm (Hyundai Fiber Co., Ltd.) was used as it was.

[0105] Experimental example

[0106] For the aerogel composites prepared in Examples 1 to 9 or the glass fiber mat prepared in Comparative Example 1, the sound absorption coefficient at each frequency, the average sound absorption coefficient, and the room temperature thermal conductivity were measured, as shown in Table 1 below.

[0107] *Sound absorption coefficient and average sound absorption coefficient per frequency: Each aerogel composite was cut into 30 cm x 30 cm pieces to prepare samples. The sound absorption coefficient was measured using a Bruel & Kjaer Corporation P-S40-20 impedance tube within the frequency range of 50 Hz to 6400 Hz, and the sound absorption coefficient per frequency was calculated using 1 / 3 octave band data. Based on the sound absorption coefficient at each frequency, the overall average sound absorption coefficient (corresponding to the overall average) and the high-frequency average sound absorption coefficient (corresponding to the average value within the high-frequency range (2500 Hz to 6300 Hz) were calculated.

[0108] In addition, for the aerogel composites prepared in Examples 1 to 3 and the glass fiber mat of Comparative Example 1, the calculated sound absorption coefficients for each frequency are shown in a graph, as shown in FIG. Figure 1 shown.

[0109] *Room temperature (23±5°C) thermal conductivity (mW / mK): Each aerogel composite or glass fiber mat was cut into 30 cm×30 cm to prepare a sample, and then the room temperature (23±5°C) thermal conductivity was measured using HFM 436 Lambda equipment from NETZSCH Co., Ltd.

[0110] Table 1

[0111]

[0112] As shown in Table 1 above and Figure 1 As shown, it can be seen that compared with the glass fiber mat of Comparative Example 1, each aerogel composite of Examples 1 to 9 prepared according to the present invention has a higher overall average sound absorption coefficient, thereby having improved sound absorption performance, and has low room temperature thermal conductivity, thereby having excellent thermal insulation performance.

[0113] In particular, it can be seen that Examples 1, 2, 4, 5, 7, and 8, which were manufactured by impregnating a fiber mat with a catalytic silica sol at a volume ratio of 0.3:1 to 0.7:1 (catalytic silica sol: fiber mat) and then performing gelation when manufacturing an aerogel composite, ensure sufficient thermal insulation performance compared to Comparative Example 1, and have further improved sound absorption coefficients per frequency and further improved high-frequency average sound absorption coefficients in the high-frequency range compared to Examples 3, 6, and 9, which were manufactured by impregnating a fiber mat with a catalytic silica sol at a volume ratio of 1:1 (catalytic silica sol: fiber mat) with the same silica concentration as in each Example and then performing gelation.

[0114] From these results, it can be determined that, when the aerogel composite is manufactured according to the method of manufacturing an aerogel composite of the present application, the macropores of the fibrous mat are reduced and the mesopores are increased, thereby improving the sound absorption rate and the thermal insulation performance, and thus the aerogel composite of the present application has excellent sound absorption performance and thermal insulation performance, and thus can be used as a sound absorption material.

Claims

1. A method for producing an aerogel composite, comprising: The catalytic silica sol is impregnated into the fiber mat at a volume ratio of 0.3 to 0.7:1 (catalytic silica sol: fiber mat), and then a gelation step S10 is performed thereon, Wherein, the catalytic silica sol is prepared by comprising the following steps: Step S1 of mixing a silica precursor, an organic solvent, and an aqueous solvent to prepare a silica precursor composition; Step S2 of mixing an organic solvent, a base catalyst, and a hydrophobizing agent to prepare a catalyst composition; and Step S3 of mixing the silica precursor composition and the catalyst composition to prepare a catalytic silica sol; The silica concentration of the silica precursor composition prepared in step S1 is 40 kg / m 3 Up to 70kg / m 3 .

2. The method according to claim 1, wherein The method for making an aerogel composite comprises: Step S20 of ripening the wet gel composite gelled in step S10; and Step S30 of drying the wet gel composite matured in step S20 to obtain an aerogel composite.

3. The method according to claim 2, wherein: The aerogel composite obtained in step S30 has pores with a pore diameter of 2 nm to 50 nm.

4. The method according to claim 1, wherein The fiber mat is a glass fiber mat.

5. The method according to claim 1, wherein The fiber mat has pores with a pore diameter of 100 μm to 1000 μm.

6. An aerogel composite produced by the method of any one of claims 1 to 5, comprising: fiber mats; and aerogel formed inside and on the surface of the fiber mat, wherein the overall average sound absorption coefficient is 0.41 or greater, and the overall average sound absorption coefficient is the average value of the sound absorption coefficient at each frequency obtained by digitizing the 1 / 3 octave band of the sound absorption rate measured in the frequency range of 50 Hz to 6400 Hz using an impedance tube P-S40-20, The high-frequency average sound absorption coefficient of the aerogel composite is greater than 0.44, and the high-frequency average sound absorption coefficient is the average value of the sound absorption coefficient of each frequency obtained by digitizing the 1 / 3 octave band of the sound absorption rate measured in the frequency range of 2500 Hz to 6400 Hz using an impedance tube P-S40-20, and The volume ratio of the mesopores of the aerogel composite is higher than the volume ratio of the macropores, the mesopores are pores with a pore diameter of 2 nm to 50 nm, and the macropores are pores with a pore diameter greater than 50 nm.

7. The aerogel composite according to claim 6, wherein The room temperature thermal conductivity of the aerogel composite is less than 30.0 mW / mK.

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