JP3100856B2 - Manufacturing method of bulk airgel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a bulk aerogel, and more particularly, to various uses such as a translucent heat insulating material, an acoustic material, a catalyst carrier, and a Cherenkov counter medium useful for solar heat collection. Daylighting that can be used for
The present invention relates to a method for producing a bulk airgel that is useful as a material that requires translucency and heat insulation as well as productivity and workability.

[0002]

2. Description of the Related Art An airgel made of silica has been known as a material having a low thermal conductivity and a light transmitting property. This airgel is available from USP 4,402,927
No. 4,432,956 and No. 4,610,863, a wet gel comprising a silica skeleton obtained by hydrolyzing and polymerizing alkoxysilane (also referred to as silicon alkoxide, alkyl silicate, etc.). The compound can be produced by drying the compound in a supercritical state above the critical point of the solvent in the presence of a solvent (dispersion medium) such as alcohol or liquefied carbon dioxide.
The airgel obtained by such a production method is useful, for example, as a heat-insulating material having a light-transmitting property. In order to obtain such an aerogel, it is necessary to remove the solvent therein without destroying the structure of the gel-like compound during the manufacturing process. A so-called supercritical drying method for removing this in a state is used.

However, in order to obtain a bulk material having a large size without destroying the structure of the gel-like compound in the above-mentioned aerogel production method, it is generally necessary to expand the production equipment, and the production time is very long. There was a problem of becoming long. This is because when the solvent in the gel compound is rapidly removed, the stress accompanying the diffusion and expansion of the solvent in the gel compound becomes large, and cracks occur. This is particularly remarkable in a method in which the solvent of the gel compound is replaced with carbon dioxide, and then the solvent in the gel compound is removed in a supercritical state of carbon dioxide.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned facts, and has as its object the object of the present invention is to provide a material having excellent heat insulating properties and the like and a light-transmitting property inherent to a porous material. ,
An object of the present invention is to provide a method for producing a bulk aerogel which can obtain a bulk having a large size without destroying the structure of the gel compound and which is excellent in productivity and workability.

[0005]

According to the method for producing a bulk airgel according to claim 1 of the present invention, a polycondensable alkoxysilane is hydrolyzed and gelled by a polycondensation reaction to form a gel-like compound. Manufacturing a bulk aerogel 2 by laminating, bonding and integrating a plurality of blocks 1 of a hydrophobic aerogel comprising a porous skeleton of silica obtained by subjecting a gel compound to a hydrophobic treatment and supercritical drying. It is characterized by.

A method of manufacturing a bulk airgel according to a second aspect of the present invention is characterized in that a plurality of blocks 1 of the airgel are directly brought into contact with each other and laminated and pressed.

A method for producing a bulk airgel according to a third aspect of the present invention is characterized in that a plurality of the airgel blocks 1 are bonded by applying a pressure of 0.005 to 0.5 kg / cm ^2. .

According to a fourth aspect of the present invention, there is provided a method of manufacturing a bulk airgel, wherein the bonding surface 1a of the block 1 of the airgel is used.
Are uneven, and are laminated in alignment with each other.

According to a fifth aspect of the present invention, there is provided a method for producing a bulk airgel, wherein the adhesive surface 1a of the block 1 of the airgel is provided.
Is characterized by having a wavy shape, a saw blade shape or a tooth shape.

In the method for producing a bulk aerogel according to claim 6 of the present invention, the density of the block 1 of the aerogel is 0.1.
It is characterized in that it is from 0.01 to 0.3 g / cm ³ .

Hereinafter, the present invention will be described in detail. The airgel block used in the method for producing a bulk airgel according to the present invention is obtained as follows. That is, for example, alcohol, water and a catalyst are added to and mixed with a polycondensable alkoxysilane, and the alkoxysilane is hydrolyzed to obtain a reaction solution (sol). The alcohol used at this time may be, for example, methanol, ethanol, isopropanol, butanol, etc., and is not particularly limited. Next, the reaction solution is placed in a container having a predetermined shape. When the polycondensation reaction of the reaction solution proceeds sufficiently, the reaction solution gels, and a gel compound is obtained. Next, if necessary, alcohol is added to this gel compound. It is preferable that the gel-like compound is one in which water and unreacted substances are removed and the solvent portion is completely replaced with alcohol (also referred to as an alcohol gel). Further, the gel-like compound is heated, if necessary, in a hydrophobizing solution in which a hydrophobizing agent is dissolved in a solvent such as alcohol to perform a hydrophobizing treatment. Next, the substrate is washed with a solvent for supercritical drying such as alcohol. The hydrophobic treatment may be performed using a supercritical fluid as a dispersion medium of the hydrophobic agent. In this case, carbon dioxide is preferable because the dispersion medium easily forms a supercritical state. Then
The gel-like compound in this state is supercritically dried, and a solvent such as alcohol or carbon dioxide is removed from the gel-like compound to obtain a block of a hydrophobic airgel.

The method for producing a bulk airgel according to the present invention is, for example, as shown in FIGS. 1 (a-1) and 1 (b-1), a block 1 of a hydrophobic airgel having a porous skeleton of silica. The bulk airgel 2 is manufactured by laminating, bonding and integrating the plurality. The aerogel constituting the bulk aerogel 2 according to the present invention is a porous silica body having translucency. Aerogel (aerogel) generally refers to a porous material obtained by removing a solvent or the like from a gel-like compound containing a solvent before drying, such as a wet alcogel, and removing the solvent by supercritical extraction. It is a dry porous gel or the like obtained by removal.

The alkoxysilane used in the present invention is an alkoxysilane represented by the following general formula, and more specifically, a bifunctional alkoxysilane represented by the following general formula, Examples include trifunctional alkoxysilanes represented by the following formulas, tetrafunctional alkoxysilanes represented by the following general formula, and oligomers of alkoxysilanes represented by the following general formula.

[0014]

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[0015]

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[0016]

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[0017]

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[0018]

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The gel compound (wet alcogel) according to the present invention is, for example, at least one selected from the group consisting of alkoxysilanes represented by the aforementioned general formulas to general formulas, or the general formulas and general formulas above. At least one selected from the group consisting of alkoxysilanes represented by the formula:
It is obtained by hydrolyzing and polycondensing a mixture containing a seed and an alkoxysilane represented by the above general formula.

Specific examples of the alkoxysilanes represented by the above general formulas to general formulas used in the present invention include:
Examples of the bifunctional alkoxysilane include, for example, dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldiethoxysilane, diphenyldimethoxysilane, methylphenyldiethoxysilane, methylphenyldimethoxysilane, diethyldiethoxysilane, diethyldimethoxysilane, and the like. Examples of the trifunctional alkoxysilane include, for example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane. Examples of the tetrafunctional alkoxysilane include , Tetramethoxysilane, tetraethoxysilane and the like, but are not particularly limited.

The alkoxysilane oligomer represented by the above general formula preferably has a degree of polymerization of 10 or less (hereinafter, those having a degree of polymerization of n are referred to as n-mers). However, it is not limited to this. The oligomer of the alkoxysilane does not need to be a compound having a uniform degree of polymerization, and may have a distribution of the degree of polymerization or may have a mixed molecular structure of a chain, a branch, and a ring. In consideration of the stability as a substance and the reaction time for producing a gel compound, a dimer to hexamer is preferable. R in the oligomer of the alkoxysilane represents an alkyl group or a phenyl group, and among them, a methyl group (—CH
_3), ethyl group (-C ₂ H ₅₎ are preferred. Specifically, in the case of an oligomer of methoxysilane, the average molecular weight is 2
In the case of an oligomer of ethoxysilane of 50 to 700, an oligomer having an average molecular weight of 300 to 900 is preferable.

In the present invention, in order to efficiently hydrolyze the alkoxysilane and carry out polycondensation, it is preferable to add a catalyst to the reaction solution containing the alkoxysilane in advance. Examples of such a catalyst include an acidic catalyst and a basic catalyst. Specifically, as the acidic catalyst, hydrochloric acid, citric acid, nitric acid, sulfuric acid, ammonium fluoride and the like are used, and as the basic catalyst, ammonia, piperidine and the like are used, but not limited thereto. Absent.

The solvent used for the hydrolysis and condensation polymerization of alkoxysilane is usually alcohol, in order to uniformly dissolve and mix the raw material alkoxysilane and water.
Acetone or the like is used, but is not limited thereto, and any solvent may be used as long as both the alkoxysilane and water are easily dissolved. However, alcohol is preferred as the solvent in view of the fact that alcohol is produced by a hydrolysis reaction in the process of producing the gel-like compound and that supercritical drying is taken into account.

The gel-like compound thus obtained is dried in the presence of a dispersion medium under supercritical conditions above the critical point of the dispersion medium to obtain an airgel block. However, in the aerogel obtained by this method, when the silica forming the skeleton has a hygroscopic property, it absorbs moisture in the atmosphere, and causes problems such as deterioration of properties such as light transmittance and heat insulating properties and shrinkage. Sometimes. In other words, when most of the surface of the silica forming the skeleton is covered with a hydrophilic group, the airgel has no tackiness and is difficult to adhere by pressure, adsorbs moisture in the atmosphere, and transmits light. In some cases, problems such as a decrease in properties such as heat insulation and heat insulation and a change in dimensions may occur. Therefore, by replacing the hydrophilic group on the silica surface with a hydrophobic group, that is, by performing a hydrophobic treatment, it is possible to increase the adhesiveness of the airgel, and at the same time, suppress a change over time in performance due to moisture adsorption or the like. As the hydrophobizing agent, one having a functional group reactive with a silanol group and a hydrophobic group is used.
Examples of the functional group that reacts with the silanol group include a halogen, an amino group, an imino group, a carboxyl group,
Examples include an alkoxyl group and a hydroxyl group. Examples of the hydrophobic group include an alkyl group, a phenyl group, and a fluoride thereof. The hydrophobizing agent may have only one type of the functional group and the hydrophobic group, or may have two or more types. Specifically, hexamethyldisilazane, hexamethyldisiloxane, trimethylchlorosilane, trimethylmethoxysilane, trimethylethoxysilane, triethylethoxysilane, triethylmethoxysilane, dimethyldichlorosilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrichlorosilane And organic compounds such as carboxylic acids such as acetic acid, formic acid and succinic acid, and alkyl halides such as methyl chloride. As the hydrophobizing agent, only one kind may be used, or two or more kinds may be used.

Here, the hydrophobizing treatment is carried out beforehand by using a liquid as a medium before supercritical drying, or by using a supercritical fluid as a medium during supercritical drying described later. These media are not particularly limited as long as they have low reactivity with the hydrophobizing agent and dissolve the hydrophobizing agent.

The gel-like compound thus obtained is dried in the presence of a dispersion medium under supercritical conditions above the critical point of the dispersion medium to obtain an aerogel.

The solvent used for supercritical drying is not particularly limited. For example, a single solvent such as ethanol, methanol, dichlorodifluoromethane, carbon dioxide, water or a mixture of two or more solvents is used. Can be mentioned.

When supercritical drying is performed using a single solvent instead of a mixed system, generally, a solvent and a gel-like compound that has been subjected to solvent replacement in the same solvent are put together in an autoclave. After the temperature and the pressure are raised to a temperature higher than the critical point of the solvent, the solvent is gradually removed, and finally the state is returned to a normal temperature and a normal pressure, thereby completing the drying. When supercritical drying is performed in a mixed system of two or more types, a method in which the temperature and pressure are set to a supercritical state in the mixed system in a drying container, and a method of raising the gel-like compound in the drying container. There is a method in which the first solvent is replaced with a second solvent to be brought into a supercritical state, the solvent is almost completely replaced, and then the solvent is removed in a supercritical state of the second solvent.

Since the surface of the aerogel block has been subjected to a hydrophobic treatment, the surface of the aerogel block has tackiness.
As shown in (a-1) and FIG. 1 (b-1), a plurality of blocks 1 of the aerogel are directly brought into contact with each other and laminated and pressed to be integrated to obtain a bulk aerogel 2.

The plurality of blocks of aerogel 1...
It is preferable that the layers are laminated and pressurized at a pressure of 0.005 to 0.5 kg / cm ² for adhesion. That is, when the pressure to be applied is less than 0.005 kg / cm ² , the plurality of airgel blocks 1...
If it exceeds g / cm ² , block 1 of aerogel
... tend to break.

FIG. 1A is a perspective view of a bulk airgel according to the present invention.
1) to FIG. 1 (a-4), and a cross section taken along line BB of FIG.
-1) to FIG. 1 (b-4). The shape of the aerogel block 1 used in the method for producing a bulk aerogel according to the present invention is not particularly limited.
(A-1) and a flat plate shape as shown in FIG. 1 (b-1). Further, FIGS. 1 (a-2) to 1 (a-
4) and FIG. 1 (b-2) to FIG. 1 (b-4), it is preferable that the adhesive surface 1a of the airgel block 1 has an uneven shape, and is laminated in alignment with each other. Examples of the uneven shape include a wave shape, a saw blade shape, and a tooth shape. That is, the adhesive surface 1 of the airgel block 1
By making a a concave-convex shape, it is possible to prevent displacement in the front-rear and left-right directions, increase the bonding area, and further improve the adhesiveness.

The method for producing a gel compound having these shapes is not particularly limited, but the shape of a container in which the reaction solution is to be put and gelled is required in advance, and the above-mentioned container is formed thereon. A method of pouring the reaction solution, covering the gel with a lid having a required shape before gelling, and then gelling may be mentioned. In addition, the thickness of the bulk airgel 2 of the present invention is appropriately selected depending on the required properties such as required light transmittance and heat insulation, and is not particularly limited.

The density of the block 1 of the airgel used in the method for producing a bulk airgel according to the present invention is not particularly limited, but is preferably 0.01 to 0.3 g / cm ³ , and more preferably 0.04 to 0.3 g / cm ^3. More preferably, it is 0.2 g / cm ³ . That is, when the density of the block 1 of the aerogel is less than 0.01 g / cm ³ , it becomes difficult to prepare the aerogel, it takes a long time to gel, and shrinkage during supercritical drying can be avoided. However, it is almost impossible to manufacture such an airgel block 1 in practice, and 0.3
If it exceeds g / cm ³ , the performance such as heat insulation and light transmission will be reduced, and it will be difficult to prepare an airgel.

Note that the densities of the blocks 1 of each aerogel may be the same or different.

The aerogel used in the method for producing a bulk aerogel according to the present invention is a structure composed of very fine silica particles, and since the particle size and the interparticle space are much smaller than the wavelength of light, a porous material is used. However, it has a light-transmitting property and is also excellent in heat insulation. However, it is very difficult to obtain a bulk material having a large size without destroying the structure of the gel compound from the viewpoint of manufacturing equipment and manufacturing time.

The bulk airgel according to the present invention is formed by laminating blocks 1 of aerogel having relatively small dimensions which are easy to produce, and since the block 1 of the aerogel has been subjected to a hydrophobic treatment. In addition, the hydrophobic groups on the surface of the block 1 of the airgel have tackiness, and the blocks of the airgel can adhere to each other with a slight pressure.

The bulk airgel according to the present invention has the same light transmission and heat insulation properties as the integral bulk airgel, and is excellent in terms of production and construction. Here, the translucency is, for example, visual transparency in a visible light wavelength region or the like, or transparency in an infrared region, but is not limited thereto.

[0038]

In the method for producing a bulk airgel according to the first aspect of the present invention, a plurality of blocks 1 of a hydrophobic airgel having a porous skeleton of silica are laminated, adhered and integrated,
Since the bulk aerogel 2 is manufactured, a bulk aerogel having excellent heat insulating properties and the like, which is characteristic of a porous material, having translucency, and having large dimensions can be easily obtained.

In the method for producing a bulk airgel according to the second aspect of the present invention, since the block 1 of the hydrophobic airgel has adhesiveness, a plurality of the blocks 1 of the airgel are directly contacted and laminated and pressed. No adhesive is required.

In the method for producing a bulk airgel according to the third aspect of the present invention, a plurality of the aerogel blocks 1 are set to 0.1.
.. Are adhered by applying a pressure of 005 to 0.5 kg / cm ² , so that a plurality of airgel blocks 1 are securely adhered without breaking.

In the method for manufacturing a bulk aerogel according to the fourth and fifth aspects of the present invention, the adhesive surface 1a of the block 1 of the aerogel is formed in a corrugated shape, a saw blade shape or a tooth shape, and is aligned with each other. Since the stacking is performed, it is possible to prevent a shift to the front, rear, left and right, increase the bonding area, and further improve the adhesion.

In the method for producing a bulk airgel according to claim 6 of the present invention, since the density of the block 1 of the airgel is 0.01 to 0.3 g / cm ³ , the preparation of the airgel is easy and the gelation is performed. And the shrinkage during supercritical drying can be reduced, and the performance such as heat insulation and light transmission is good.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be specifically described below with reference to the drawings.

Hereinafter, specific examples and comparative examples of the present invention will be described, but the present invention is not limited to the following examples.

Example 1 An oligomer of tetramethoxysilane having an average molecular weight of 470 (manufactured by Colcoat Co., Ltd .; trade name: methylsilicate 51) was mixed with ethanol (special grade reagent manufactured by Nacalai Tesque Co., Ltd.), water and 0.01 mol / l. Of tetramethoxysilane: ethanol: water: aqueous ammonia solution = 1: 12.
A reaction solution (hereinafter, referred to as sol) having a mixing ratio of 0: 20: 2.16 (molar ratio) was obtained.

The sol was poured into a container and allowed to stand at room temperature to gel. The dimensions of the obtained gel compound were 54 mm × 38 mm × 8 mm.

Next, this gel compound was heated at 18 ° C. and 55 k
An operation of replacing the ethanol in the gel with carbon dioxide in carbon dioxide at g / cm ² was performed for 2 to 3 hours. After that, the inside of the container is supercritical condition of carbon dioxide, 80 ° C.,
160 kg / cm ² , supercritical drying (solvent removal) 1
Performed for 0 hours. Next, to the atmosphere in the supercritical state, hexamethyldisilazane as a hydrophobizing agent was added at a ratio of 0.3 mol / liter, and the hydrophobizing agent was diffused into the supercritical fluid over 2 hours. The gel compound was left in a supercritical fluid and subjected to a hydrophobic treatment. Thereafter, the pressure was reduced after circulating carbon dioxide in a supercritical state to remove ethanol and the hydrophobizing agent contained in the gel compound. It took 15 hours from injection of the hydrophobizing agent to decompression. The airgel block was removed from the container. Next, six blocks of the obtained aerogel were stacked, pressed under a pressure of 0.05 kg / cm ² , and adhered to obtain a bulk aerogel. The thickness of the obtained bulk airgel was 48 mm, and the adhesiveness of the blocks 1 of the airgel was good. The bulk density, thermal conductivity, and light transmittance of the bulk aerogel were measured, and the results are shown in Table 1, including the configuration, thickness, and presence or absence of a hydrophobic treatment of the bulk aerogel.

Example 2 Using a sol having the same composition as the sol used in Example 1, one gel-like compound 3 as shown in FIG. 2A was obtained, and as shown in FIG. In addition, four gel-like compounds 4 as shown in FIG.
2 in the same manner as in Example 1 except that one
As shown in (d), a bulk airgel 2 composed of the airgel block 1 was obtained. The thickness of the obtained bulk airgel is 48 mm, and the airgel block 1
The adhesion between the comrades was very good. The bulk density, thermal conductivity, and light transmittance of the bulk aerogel were measured, and the results are shown in Table 1, including the configuration, thickness, and presence or absence of a hydrophobic treatment of the bulk aerogel.

Example 3 The same procedure as in Example 2 was carried out except that the mixing ratio of the sol was set to oligomer (tetramethoxysilane): ethanol: water: aqueous ammonia = 1: 70: 20: 0.6 (molar ratio). Then, as shown in FIG.
Bulk airgel 2 consisting of airgel blocks 1
I got The thickness of the obtained bulk airgel is 48 mm.
The adhesiveness of the airgel blocks 1 was very good. The bulk density, thermal conductivity, and light transmittance of the bulk aerogel were measured, and the results are shown in Table 1, including the configuration, thickness, and presence or absence of a hydrophobic treatment of the bulk aerogel.

Example 4 As shown in FIG. 2 (b), the mixing ratio of the sol to obtain the gelled compound 4 was as follows: oligomer of tetramethoxysilane: ethanol: water: aqueous ammonia solution = 1: 120: 20: 2.16 (molar ratio), and as shown in FIG. 2 (a), gelled compound 3 and FIG. 2 (c)
The mixing ratio of the sol for obtaining the gelled compound 5 as shown in FIG.
As in Example 2, except that water: aqueous ammonia = 1: 70: 20: 0.6 (molar ratio).
As shown in (d), a bulk airgel 2 composed of the airgel block 1 was obtained. The thickness of the obtained bulk airgel is 48 mm, and the airgel block 1
The adhesion between the comrades was very good. The bulk density, thermal conductivity, and light transmittance of the bulk aerogel were measured, and the results are shown in Table 1, including the configuration, thickness, and presence or absence of a hydrophobic treatment of the bulk aerogel. Here, the bulk density of the block 1 of the aerogel corresponding to the gel compound 4 is 0.04 g / c.
In c, the bulk density of the block 1 of the airgel corresponding to the gel compounds 3 and 5 was 0.07 g / cc.

[0051]

[Table 1]

(Comparative Example 1) The shape of the gel compound was 54 m
m × 38 mm × 48 mm, and an attempt was made to obtain a bulk airgel in the same manner as in Example 1 except that an integrated gel compound was obtained. However, the removal of the solvent was insufficient, and the shrinkage and cloudiness occurred. The aerogel was completely destroyed. Table 1 shows the structure of the bulk airgel and the presence or absence of a hydrophobic treatment.

Comparative Example 2 In the same manner as in Example 2, except that the hydrophobizing treatment of the gel compound was not performed, FIG.
As shown in (d), a bulk airgel 2 composed of the airgel block 1 was obtained. The thickness of the obtained bulk airgel was 48 mm. However, the adhesion between the airgel blocks 1 was not so good. The bulk density, thermal conductivity, and light transmittance of the bulk aerogel were measured, and the results are shown in Table 1, including the configuration, thickness, and presence or absence of a hydrophobic treatment of the bulk aerogel.

The bulk density was determined by measuring the weight of each aerogel block, calculating the volume, and calculating the weight / volume. The thermal conductivity was measured using an ASTM using a thermal conductivity measuring device manufactured by Eiko Seiki Co., Ltd. by the steady method.
-Set temperature 20 ° C and 40 ° C by a method based on C518
It measured on condition of. The light transmittance is measured by measuring the spectral distribution of the transmitted light of the sample in the visible light range and determining the visible light transmittance by JI.
It was determined based on S-R3106.

[0055]

According to the method for producing a bulk airgel according to the first aspect of the present invention, a plurality of blocks of a hydrophobic aerogel having a porous skeleton of silica are laminated, adhered and integrated to form a bulk aerogel. Because it is manufactured, it is excellent in performance such as heat insulation characteristic of porous material, it has translucency, and it can be appropriately combined with airgel blocks with small dimensions, so it is excellent in productivity and workability, and required performance It is also possible to appropriately combine blocks of aerogels having different densities or change the thickness of the bulk aerogel in accordance with the requirements, and to meet various demands such as easily obtaining bulk aerogels having large dimensions.

According to the method for producing a bulk airgel according to the second aspect of the present invention, since the blocks of the hydrophobic airgel have adhesiveness, a plurality of blocks of the airgel are directly contacted and laminated and pressed. Since no adhesive is required, the productivity and workability are further improved.

According to the method for producing a bulk airgel according to the third aspect of the present invention, a plurality of aerogel blocks are pressurized at a pressure of 0.005 to 0.5 kg / cm ² and adhered. Larger bulk aerogels are more easily obtained because the blocks are securely bonded without breaking.

According to the method for manufacturing a bulk airgel according to the fourth and fifth aspects of the present invention, the adhesive surface of the block of the airgel is formed in a corrugated shape, a saw blade shape, a tooth shape or the like, and is aligned with each other. Since it is laminated, it can be prevented from shifting to the front, rear, left and right, the bonding area increases,
Because of the improved adhesion, bulk aerogels with large dimensions are more easily obtained.

According to the method for producing a bulk airgel according to the sixth aspect of the present invention, the density of the block 1 of the airgel is set to 0.1.
Since it is 0.01 to 0.3 g / cm ³ , the preparation of the airgel is easy, the time required for gelation is shortened, the shrinkage during supercritical drying can be reduced, and the properties such as heat insulation and light transmission are obtained. Is good, so that a bulk airgel excellent in productivity, workability and quality can be easily obtained.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a method for producing a bulk airgel according to an embodiment of the present invention, wherein (a) is a perspective view of the bulk airgel, and (a-1) to (a-4) are ( a) A
FIG. 4A is a cross-sectional view, and (b-1) to (b-4)
It is a BB sectional view of (a). (A-1) and (b-
1) is a cross-sectional view of a bulk airgel using a flat airgel block, (a-2) and (b-2) are cross-sectional views of a bulk airgel using a wavy airgel block, and (a). -3) and (b-3) are cross-sectional views of a bulk airgel using a saw blade-shaped airgel block, and (a-4) and (b-4) use a tooth-shaped airgel block. It is sectional drawing of the bulk airgel which was put.

FIGS. 2A and 2B are explanatory diagrams of a method for producing a bulk airgel according to another embodiment of the present invention, in which FIG. 2A is a gel compound corresponding to an airgel block in the uppermost layer of the bulk airgel, and FIG. The gel-like compound corresponding to the aerogel block in the intermediate layer of the bulk aerogel and (c) are three-view (a plan view, an elevation view, and the like) of the gel-like compound corresponding to the aerogel block in the lowermost layer of the bulk aerogel. (D) is a perspective view of a bulk aerogel composed of aerogel blocks.

[Explanation of symbols]

 1 Aerogel block 1a Adhesive surface 2 Bulk aerogel

Continuation of the front page (56) References JP-A-4-17942 (JP, A) JP-A-4-198238 (JP, A) JP-A-5-49910 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) B32B 1/00-35/00 C01B 33/16 C08J 9/28 102

Claims (6)

(57) [Claims] 1. A method of hydrolyzing an alkoxysilane having polycondensability, gelling by a polycondensation reaction to form a gel compound, and subjecting the gel compound to hydrophobic treatment and supercritical drying to obtain a porous silica. A method for producing a bulk aerogel, characterized in that a plurality of hydrophobic aerogel blocks (1) each comprising a porous skeleton are laminated, adhered and integrated to produce a bulk aerogel (2). 2. A method for producing a bulk airgel according to claim 1, wherein a plurality of said airgel blocks (1) are directly brought into contact with each other and laminated and pressed. 3. The bulk of claim 1 or ² , wherein a plurality of the airgel blocks (1) are bonded by applying a pressure of 0.005 to 0.5 kg / cm ^2. Aerogel manufacturing method. 4. The method for producing a bulk airgel according to claim 1, wherein the adhesive surface (1a) of the block (1) of the airgel has an uneven shape and is laminated in alignment with each other. 5. The method for producing a bulk airgel according to claim 4, wherein the uneven surface of the adhesive surface (1a) of the block (1) of the airgel has a wavy shape, a saw blade shape or a tooth shape. 6. The method for producing a bulk airgel according to claim 1, wherein the density of the block (1) of the airgel is 0.01 to 0.3 g / cm ³ .