WO2017170498A1

WO2017170498A1 - Aerogel composite, and support member and adiabatic material provided with aerogel composite

Info

Publication number: WO2017170498A1
Application number: PCT/JP2017/012556
Authority: WO
Inventors: 海斗小暮; 智彦小竹; 正人宮武; 竜也牧野
Original assignee: 日立化成株式会社
Priority date: 2016-03-29
Filing date: 2017-03-28
Publication date: 2017-10-05
Also published as: TW201806862A; JPWO2017170498A1

Abstract

The present disclosure pertains to an aerogel composite containing an aerogel component and silica particles derived from an alkoxysilane, an aerogel composite containing silica particles derived from an alkoxysilane as a component that constitutes a three-dimensional mesh skeleton, and a aerogel composite that is a dried product of a wet gel that is a condensate of a sol containing silica particles derived from an alkoxysilane and at least one selected from the group consisting of silicon compounds having a hydrolyzable functional group or a condensable functional group and hydrolysis products of silicon compounds having a hydrolyzable functional group.

Description

Airgel composite, support member with airgel composite, and heat insulating material

The present disclosure relates to an airgel composite, a support member with an airgel composite, and a heat insulating material.

Silica airgel is known as a material having low thermal conductivity and heat insulation. Silica airgel is useful as a functional material having excellent functionality (such as heat insulation), unique optical characteristics, and unique electrical characteristics. Silica airgel is used, for example, as an electronic substrate material that utilizes the ultra-low dielectric constant characteristics of silica airgel, a heat-insulating material that utilizes the high thermal insulation property of silica airgel, and a light-reflecting material that utilizes the ultra-low refractive index of silica airgel. ing.

As a method for producing such a silica airgel, a supercritical drying method is known in which a gel-like compound (alcogel) obtained by hydrolyzing and polymerizing alkoxysilane is dried under supercritical conditions of a dispersion medium. (For example, refer to Patent Document 1). In the supercritical drying method, an alcogel and a dispersion medium (solvent used for drying) are introduced into a high-pressure vessel, and the dispersion medium is applied to the supercritical fluid by applying a temperature and pressure above its critical point to form a supercritical fluid. It is a method of removing the solvent. However, since the supercritical drying method requires a high-pressure process, capital investment is required for a special apparatus that can withstand supercriticality, and much labor and time are required.

Therefore, a technique for drying alcogel using a general-purpose method that does not require a high-pressure process has been proposed. As such a method, for example, a method of improving the strength of the resulting alcogel by using a monoalkyltrialkoxysilane and a tetraalkoxysilane in combination at a specific ratio as a gel material and drying at normal pressure is known. (For example, refer to Patent Document 2). However, when such atmospheric pressure drying is employed, the gel tends to contract due to stress caused by the capillary force inside the alcogel.

U.S. Pat. No. 4,402,927 JP 2011-93744 A

As described above, while the problems of the conventional manufacturing process have been studied from various viewpoints, even if any of the above processes is adopted, the obtained airgel is poor in handling and large in size. Because it is difficult, there is a problem in productivity. For example, the agglomerated airgel obtained by the above process may be broken simply by trying to lift it by hand. This is presumably due to the fact that the density of the airgel is low and that the airgel has a pore structure in which fine particles of about 10 nm are weakly connected.

As a method for improving such problems of conventional aerogels, a method of imparting flexibility to the gel by enlarging the pore diameter of the gel to the micrometer scale is conceivable. However, the airgel thus obtained has a problem that the thermal conductivity is greatly increased, and the excellent heat insulating property of the airgel is lost.

The present disclosure has been made in view of the above circumstances, and an object thereof is to provide an airgel composite excellent in heat insulation and flexibility. The present disclosure also provides a support member with an airgel composite and a heat insulating material that carry the airgel composite.

As a result of intensive studies to achieve the above object, the present inventor has achieved excellent heat insulation and flexibility by using an airgel composite in which silica particles prepared from a predetermined raw material are combined in an airgel. And were found to be expressed.

The present disclosure provides an airgel composite containing an airgel component and alkoxysilane-derived silica particles. The airgel composite of the present disclosure is excellent in heat insulation and flexibility, unlike the airgel obtained by the prior art.

The airgel composite can have a three-dimensional network skeleton formed from an airgel component and silica particles, and pores. Thereby, it becomes easy to improve heat insulation and a softness | flexibility further.

The present disclosure also provides an airgel composite containing alkoxysilane-derived silica particles as a component constituting a three-dimensional network skeleton. The airgel composite thus obtained is excellent in heat insulation and flexibility.

The present disclosure also includes a group consisting of alkoxysilane-derived silica particles, a silicon compound having a hydrolyzable functional group or a condensable functional group, and a hydrolysis product of the silicon compound having a hydrolyzable functional group. An airgel composite that is a dried product of a wet gel that is a condensate of a sol containing at least one selected from the above. The airgel composite thus obtained is excellent in heat insulation and flexibility.

In addition, the airgel composite mentioned above also hydrolyzes silica particles derived from alkoxysilane, a silicon compound having a hydrolyzable functional group or a condensable functional group, and a silicon compound having a hydrolyzable functional group. It may be a dried product of a wet gel that is a condensate of a sol containing at least one selected from the group consisting of products.

In the present disclosure, the silicon compound may include a polysiloxane compound having a hydrolyzable functional group or a condensable functional group. Thereby, the further outstanding heat insulation and softness | flexibility can be achieved.

The average primary particle diameter of the silica particles can be 1 to 500 nm. Thereby, it becomes easy to improve heat insulation and a softness | flexibility further.

The silica particles can be colloidal silica particles. Thereby, the further outstanding heat insulation and softness | flexibility can be achieved.

The present disclosure further provides a support member with an airgel composite comprising the airgel composite and a support member supporting the airgel composite. According to the present disclosure, since the airgel composite has excellent heat insulating properties and flexibility, it can exhibit excellent heat insulating properties and excellent flexibility that is difficult to achieve with conventional airgels.

The present disclosure further provides a heat insulating material comprising the airgel composite. The heat insulating material according to the present disclosure exhibits excellent heat insulating properties and excellent flexibility that is difficult to achieve with conventional heat insulating materials because the airgel composite has excellent heat insulating properties and flexibility. Can do.

According to the present disclosure, an airgel composite excellent in heat insulation and flexibility can be provided. That is, it is possible to provide an airgel composite that exhibits excellent heat insulating properties, improves handleability, can be increased in size, and can increase productivity. Thus, the airgel composite excellent in heat insulation and flexibility has a possibility of being used for various purposes. According to the present disclosure, it is also possible to provide a support member with an airgel composite formed by supporting such an airgel composite, and a heat insulating material. Here, an important point according to the present disclosure is that it becomes easier to control heat insulation and flexibility than conventional aerogels. This is not possible with conventional aerogels that require sacrificing thermal insulation to obtain flexibility or sacrificing flexibility to obtain thermal insulation. The above “excellent in heat insulation and flexibility” does not necessarily mean that both numerical values representing both characteristics are high. For example, “excellent flexibility while maintaining good heat insulation” , “Excellent thermal insulation while maintaining good flexibility” and the like.

It is a figure showing typically the fine structure of the airgel composite concerning one embodiment of this indication. It is a figure which shows the calculation method of the biaxial average primary particle diameter of particle | grains. The surface of the airgel composite in the foil-like support member with the airgel composite obtained in Example 4 is (a) 10,000 times, (b) 50,000 times, (c) 200,000 times, and (d) 350,000. It is the SEM image observed by each magnification.

Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the drawings as the case may be. However, the present disclosure is not limited to the following embodiment.

<Definition>
In this specification, a numerical range indicated by using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or the lower limit value of a numerical range in a certain step may be replaced with the upper limit value or the lower limit value of a numerical range in another step. In the numerical range described in this specification, the upper limit value or the lower limit value of the numerical range may be replaced with the values shown in the examples. “A or B” only needs to include either A or B, and may include both. The materials exemplified in the present specification can be used singly or in combination of two or more unless otherwise specified. In the present specification, the content of each component in the composition means the total amount of the plurality of substances present in the composition unless there is a specific notice when there are a plurality of substances corresponding to each component in the composition. means.

<Airgel composite>
In a narrow sense, dry gel obtained by using supercritical drying method for wet gel is aerogel, dry gel obtained by drying under atmospheric pressure is xerogel, dry gel obtained by freeze-drying is cryogel and However, in the present embodiment, the obtained low-density dried gel is referred to as an aerogel regardless of the drying method of the wet gel. In other words, in the present embodiment, the airgel means “a gel composed of a microporous solid whose dispersed phase is a gas”, which is an aerogel in a broad sense, that is, “Gel compressed of a microporous solid in which the dispersed phase is a gas”. To do. In general, the inside of an airgel has a network-like fine structure, and has a cluster structure in which airgel particles of about 2 to 20 nm (particles constituting the airgel) are bonded. Between the skeletons formed by the clusters, there are pores less than 100 nm, and a three-dimensionally fine porous structure is formed. In addition, the airgel in this embodiment is a silica airgel which has a silica as a main component. Examples of the silica airgel include so-called organic-inorganic hybrid silica airgel into which an organic group (such as a methyl group) or an organic chain is introduced. In addition, the airgel composite of the present embodiment has a cluster structure that is a feature of the above airgel while silica particles are composited in the airgel, and has a three-dimensionally fine porous structure. ing.

The airgel composite of this embodiment contains an airgel component and silica particles. Although not necessarily meaning the same concept as this, the airgel composite of the present embodiment can also be expressed as containing silica particles as a component constituting the three-dimensional network skeleton. . The airgel composite of this embodiment is excellent in heat insulation and flexibility as described later. In particular, since the flexibility is excellent, the handling property as an airgel composite is improved and the size can be increased, so that the productivity can be increased. In addition, such an airgel composite is obtained by making silica particles exist in the airgel production environment. And the merit by the presence of silica particles is not only that the heat insulation and flexibility of the composite itself can be improved, but also shortening the time of the wet gel generation process described later, or simplifying the drying process from the washing and solvent replacement process. Is also possible. In addition, shortening of the time of this process and simplification of a process are not necessarily calculated | required when producing the airgel composite which is excellent in a softness | flexibility.

In this embodiment, the composite aspect of an airgel component and a silica particle is various. For example, the airgel component may be in an indeterminate form such as a film or may be in the form of particles (aerogel particles). In any embodiment, since the airgel component is in various forms and exists between the silica particles, it is presumed that flexibility is imparted to the skeleton of the composite.

First, the composite mode of the airgel component and the silica particles includes a mode in which an amorphous airgel component is interposed between the silica particles. As such an embodiment, specifically, for example, an embodiment in which silica particles are coated with a film-like airgel component (silicone component) (an embodiment in which the airgel component encloses silica particles), the airgel component serves as a binder, and the silica particles , A mode in which the airgel component is filled with a plurality of silica particle gaps, a mode of a combination of these modes (a mode in which silica particles arranged in a cluster are coated with the airgel component, etc.) An embodiment is mentioned. Thus, in this embodiment, the airgel composite can have a three-dimensional network skeleton composed of silica particles and an airgel component (silicone component), and there is no particular limitation on the specific mode (form).

On the other hand, as will be described later, in the present embodiment, the airgel component may be in the form of a clear particle as shown in FIG.

The mechanism by which such various aspects occur in the airgel composite of the present embodiment is not necessarily clear, but the present inventor speculates that the generation rate of the airgel component in the gelation process is involved. For example, the production speed of the airgel component tends to vary by varying the number of silanol groups in the silica particles. Further, the production rate of the airgel component also tends to fluctuate by changing the pH of the system.

This suggests that the aspect of the airgel composite (size, shape, etc. of the three-dimensional network skeleton) can be controlled by adjusting the size, shape, silanol group number, system pH, etc. of the silica particles. Therefore, it is considered that the density, porosity, etc. of the airgel composite can be controlled, and the heat insulating property and flexibility of the airgel composite can be controlled. In addition, the three-dimensional network skeleton of the airgel composite may be composed of only one kind of the various aspects described above, or may be composed of two or more kinds of aspects.

Hereinafter, the airgel composite of the present embodiment will be described using FIG. 1 as an example. However, as described above, the present disclosure is not limited to the aspect of FIG. However, for matters common to any of the above aspects (type, size, content, etc. of silica particles), the following descriptions can be referred to as appropriate.

FIG. 1 is a diagram schematically illustrating a fine structure of an airgel composite according to an embodiment of the present disclosure. As shown in FIG. 1, the airgel composite 10 includes a three-dimensional network skeleton formed by the airgel particles 1 constituting the airgel component being partially linked in a three-dimensional manner through silica particles 2; And pores 3 surrounded by the skeleton. At this time, it is assumed that the silica particles 2 are interposed between the airgel particles 1 and function as a skeleton support that supports the three-dimensional network skeleton. Therefore, it is thought that by having such a structure, moderate strength is imparted to the airgel while maintaining the heat insulation and flexibility as the airgel. In this embodiment, the airgel composite may have a three-dimensional network skeleton formed by three-dimensionally connecting silica particles randomly through the airgel particles. Silica particles may be covered with airgel particles. In addition, since the said airgel particle (aerogel component) is comprised from a silicon compound, it is guessed that the affinity to a silica particle is high. Therefore, in this embodiment, it is considered that the silica particles were successfully introduced into the three-dimensional network skeleton of the airgel. In this respect, it is considered that the silanol groups of the silica particles also contribute to the affinity between them.

The airgel particle 1 is considered to be in the form of secondary particles composed of a plurality of primary particles, and is generally spherical. The airgel particle 1 may have an average particle size (that is, a secondary particle size) of 2 nm or more, may be 5 nm or more, and may be 10 nm or more. The average particle diameter may be 50 μm or less, may be 2 μm or less, and may be 200 nm or less. That is, the average particle diameter can be 2 nm to 50 μm, but may be 5 nm to 2 μm, or 10 nm to 200 nm. When the airgel particle 1 has an average particle diameter of 2 nm or more, an airgel composite having excellent flexibility can be easily obtained. On the other hand, when the average particle diameter is 50 μm or less, an airgel composite having excellent heat insulation can be easily obtained. . The average particle diameter of the primary particles constituting the airgel particles 1 can be set to 0.1 nm to 5 μm from the viewpoint of easy formation of secondary particles having a low density porous structure. It may be 200 nm, or 1 nm to 20 nm.

Silica particles 2 are alkoxysilane-derived silica particles. That is, as the silica particles 2, silica particles obtained using alkoxysilane as a raw material can be used. When the raw material is alkoxysilane, the silica particles 2 can be produced by a sol-gel method. By producing silica particles by the sol-gel method, the pH in the system becomes near neutral, and the hydrolysis reaction rate of the silane component can be easily controlled. Examples of such silica particles include colloidal silica particles produced by a sol-gel reaction of alkoxysilane. Colloidal silica particles have high monodispersity and are easy to suppress aggregation in the sol.

Examples of the alkoxysilane include tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, trimethoxysilane, triethoxysilane, triethoxysilane, dimethoxysilane, diethoxysilane, and dibutoxysilane. Commercially available products of alkoxysilane-derived silica particles include, for example, product names “PL-2L”, “Pl-5”, “HL-3L”, “PL-3L”, “PL-3H” of Fuso Chemical Industries, Ltd. And “HL-3”.

The average primary particle diameter of the silica particles 2 can be 1 nm or more because it is easy to impart an appropriate strength to the airgel and it is easy to obtain an airgel composite having excellent shrinkage resistance during drying. It may be 20 nm or more. On the other hand, since it becomes easy to suppress the solid heat conduction of the silica particles and it becomes easy to obtain an airgel composite excellent in heat insulation, the average primary particle diameter can be 500 nm or less, and may be 300 μm or less, 100 μm It may be the following. That is, the average primary particle diameter of the silica particles 2 can be 1 to 500 nm, 5 to 300 nm, or 20 to 100 nm.

It is presumed that the airgel particle 1 (airgel component) and the silica particle 2 are bonded in the form of hydrogen bonding or chemical bonding. At this time, the hydrogen bond or the chemical bond is considered to be formed by the silanol group of the airgel particle 1 (aerogel component) and / or the reactive group other than the silanol group and the silanol group of the silica particle 2. Therefore, it is thought that moderate strength is easily imparted to the airgel when the bonding mode is chemical bonding. Considering this, the particles to be combined with the airgel component are not limited to silica particles, and inorganic particles or organic particles having a silanol group on the particle surface can also be used.

The number of silanol groups per gram of the silica particles 2 is 10 × 10 ¹⁸ because it can have better reactivity with the airgel particles 1 (aerogel component) and it is easy to obtain an airgel composite having excellent shrinkage resistance. Pieces / g or more, 50 × 10 ¹⁸ pieces / g or more, or 100 × 10 ¹⁸ pieces / g or more. On the other hand, since it becomes easy to suppress the rapid gelation at the time of sol preparation and it becomes easy to obtain a homogeneous airgel composite, the number of silanol groups can be 1000 × 10 ¹⁸ pieces / g or less, and 800 × 10 ^18. Pieces / g or less, or 700 × 10 ¹⁸ pieces / g or less. That is, the number of silanol groups can be 10 × 10 ¹⁸ to 1000 × 10 ¹⁸ pieces / g, but it may be 50 × 10 ¹⁸ to 800 × 10 ¹⁸ pieces / g, or 100 × 10 ¹⁸ to 700. X10 ¹⁸ pieces / g may be sufficient.

In the present embodiment, the average particle size of the particles (the average secondary particle size of the airgel particles and the average primary particle size of the silica particles) is measured using a scanning electron microscope (hereinafter abbreviated as “SEM”). It can be obtained by directly observing the cross section of. For example, the particle diameter of each airgel particle or silica particle can be obtained from the three-dimensional network skeleton based on the diameter of the cross section. The diameter here means the diameter when the cross section of the skeleton forming the three-dimensional network skeleton is regarded as a circle. The diameter when the cross section is regarded as a circle is the diameter of the circle when the area of the cross section is replaced with a circle having the same area. In calculating the average particle diameter, the diameter of a circle is obtained for 100 particles, and the average is taken.

In addition, about a silica particle, it is possible to measure an average particle diameter from a raw material. For example, the biaxial average primary particle diameter is calculated as follows from the result of observing 20 arbitrary particles by SEM. That is, when colloidal silica particles having a solid content concentration of 5 to 40% by mass, which are normally dispersed in water, are taken as an example, a chip with a 2 cm square wafer with a pattern wiring is immersed in the dispersion of colloidal silica particles for about 30 seconds. After that, the chip is rinsed with pure water for about 30 seconds and blown dry with nitrogen. Thereafter, the chip is placed on a sample stage for SEM observation, an acceleration voltage of 10 kV is applied, the silica particles are observed at a magnification of 100,000, and an image is taken. 20 silica particles are arbitrarily selected from the obtained image, and the average of the particle diameters of these particles is defined as the average particle diameter. At this time, when the selected silica particle has a shape as shown in FIG. 2, a rectangle (circumscribed rectangle L) circumscribing the silica particle 2 and arranged so that the long side is the longest is led. And the long side of the circumscribed rectangle L is X, the short side is Y, and the biaxial average primary particle diameter is calculated as (X + Y) / 2, and is defined as the particle diameter of the particle.

The size of the pores 3 in the airgel composite will be described in the section of [Density and porosity] described later.

Since the content of the airgel component contained in the allogel composite is easily imparted with appropriate strength, it can be 4 parts by mass or more with respect to 100 parts by mass of the total amount of the airgel composite. There may be. Since the said content becomes easy to acquire better heat insulation, it can be 25 mass parts or less with respect to 100 mass parts of total amounts of an airgel composite, and may be 20 mass parts or less. That is, the content of the airgel component contained in the airgel composite can be 4 to 25 parts by mass with respect to 100 parts by mass of the total amount of the airgel composite, but may be 10 to 20 parts by mass.

Since the content of the silica particles contained in the airgel composite can be easily imparted with an appropriate strength to the airgel composite, it can be 1 part by mass or more with respect to 100 parts by mass of the total amount of the airgel composite. It may be greater than or equal to parts by mass. The content can be suppressed to 25 parts by mass or less, or may be 15 parts by mass or less because it is easy to suppress the solid heat conduction of the silica particles. That is, it can be 1 to 25 parts by mass with respect to 100 parts by mass of the total amount of the airgel composite, but may be 3 to 15 parts by mass.

In addition to these airgel components and silica particles, the airgel composite may further contain other components such as carbon graphite, an aluminum compound, a magnesium compound, a silver compound, and a titanium compound for the purpose of suppressing heat radiation. The content of other components is not particularly limited, but can be 1 to 5 parts by mass with respect to 100 parts by mass of the total amount of the airgel complex from the viewpoint of sufficiently securing the desired effect of the airgel complex.

<Specific embodiment of airgel composite>
The airgel composite of this embodiment includes alkoxysilane-derived silica particles, a silicon compound having a hydrolyzable functional group or a condensable functional group (in the molecule), and silicon having a hydrolyzable functional group. It may be a dried product of a wet gel which is a condensate of a sol containing at least one selected from the group consisting of hydrolysis products of compounds. That is, the airgel composite of the present embodiment comprises silica particles derived from alkoxysilane, a silicon compound having a hydrolyzable functional group or a condensable functional group (in the molecule), and a hydrolyzable functional group. It can be obtained by drying a wet gel derived from a sol containing at least one selected from the group consisting of hydrolysis products of silicon compounds. By adopting these aspects, the heat insulating property and flexibility of the airgel composite are further improved. The condensate may be obtained by a condensation reaction of a hydrolysis product obtained by hydrolysis of a silicon compound having a hydrolyzable functional group, and may be a condensable function that is not a functional group obtained by hydrolysis. It may be obtained by a condensation reaction of a silicon compound having a group. The silicon compound only needs to have at least one of a hydrolyzable functional group and a condensable functional group, and may have both a hydrolyzable functional group and a condensable functional group. In addition, each airgel composite to be described later is such that the airgel composite of the present embodiment includes particles derived from alkoxysilane, a silicon compound having a hydrolyzable functional group or a condensable functional group, and hydrolysate. A wet gel formed from a sol containing at least one selected from the group consisting of hydrolyzed products of silicon compounds having degradable functional groups, and dried wet sol derived from the sol Thing).

The airgel composite of the present embodiment can contain polysiloxane having a main chain including a siloxane bond (Si—O—Si). The airgel composite may have the following M unit, D unit, T unit or Q unit as a structural unit.

In the above formula, R represents an atom (hydrogen atom or the like) or an atomic group (alkyl group or the like) bonded to a silicon atom. The M unit is a unit composed of a monovalent group in which a silicon atom is bonded to one oxygen atom. The D unit is a unit composed of a divalent group in which a silicon atom is bonded to two oxygen atoms. The T unit is a unit composed of a trivalent group in which a silicon atom is bonded to three oxygen atoms. The Q unit is a unit composed of a tetravalent group in which a silicon atom is bonded to four oxygen atoms. Information on the content of these units can be obtained by Si-NMR.

Examples of the hydrolyzable functional group include an alkoxy group. Examples of the condensable functional group (excluding the functional group corresponding to the hydrolyzable functional group) include a hydroxyl group, a silanol group, a carboxyl group, and a phenolic hydroxyl group. The hydroxyl group may be contained in a hydroxyl group-containing group such as a hydroxyalkyl group. Each of the hydrolyzable functional group and the condensable functional group may be used alone or in admixture of two or more.

The silicon compound can include a silicon compound having an alkoxy group as a hydrolyzable functional group, and can also include a silicon compound having a hydroxyalkyl group as a condensable functional group. The silicon compound can have at least one selected from the group consisting of an alkoxy group, a silanol group, a hydroxyalkyl group, and a polyether group from the viewpoint of improving the flexibility of the airgel composite. The silicon compound can have at least one selected from the group consisting of an alkoxy group and a hydroxyalkyl group from the viewpoint of improving the compatibility of the sol.

From the viewpoint of improving the reactivity of the silicon compound and reducing the thermal conductivity of the airgel composite, the number of carbon atoms of each of the alkoxy group and the hydroxyalkyl group can be 1 to 6, and the flexibility of the airgel composite is improved. It may be 2 to 4 from the viewpoint of further improvement. As an alkoxy group, a methoxy group, an ethoxy group, and a propoxy group are mentioned, for example. Examples of the hydroxyalkyl group include a hydroxymethyl group, a hydroxyethyl group, and a hydroxypropyl group.

As the silicon compound having a hydrolyzable functional group or a condensable functional group, a silicon compound (silicon compound) other than the polysiloxane compound described later can be used. That is, the airgel composite of this embodiment includes alkoxysilane-derived silica particles, a silicon compound having a hydrolyzable functional group or a condensable functional group (excluding a polysiloxane compound), and a hydrolyzable functional group. A wet gel dried product which is a condensate of a sol containing at least one compound selected from the group consisting of hydrolysis products of silicon compounds having a group (hereinafter sometimes referred to as “silicon compound group”). Also good. The number of silicon atoms in the molecule of the silicon compound can be 1 or 2.

The silicon compound having a hydrolyzable functional group is not particularly limited, and examples thereof include alkyl silicon alkoxides. In the alkyl silicon alkoxide, from the viewpoint of improving water resistance, the number of hydrolyzable functional groups may be 3 or less, or 2 to 3. Examples of the alkyl silicon alkoxide include monoalkyltrialkoxysilane, monoalkyldialkoxysilane, dialkyldialkoxysilane, monoalkylmonoalkoxysilane, dialkylmonoalkoxysilane and trialkylmonoalkoxysilane. Examples of the alkyl silicon alkoxide include methyltrimethoxysilane, methyldimethoxysilane, dimethyldimethoxysilane, and ethyltrimethoxysilane.

The silicon compound having a condensable functional group is not particularly limited. For example, silane tetraol, methyl silane triol, dimethyl silane diol, phenyl silane triol, phenyl methyl silane diol, diphenyl silane diol, n-propyl silane triol, Examples include hexyl silane triol, octyl silane triol, decyl silane triol, and trifluoropropyl silane triol.

A silicon compound having a hydrolyzable functional group or a condensable functional group is a reactive group different from the hydrolyzable functional group and the condensable functional group (hydrolyzable functional group and condensable functional group). It may further have a functional group (not applicable). Examples of the reactive group include an epoxy group, a mercapto group, a glycidoxy group, a vinyl group, an acryloyl group, a methacryloyl group, and an amino group. The epoxy group may be contained in an epoxy group-containing group such as a glycidoxy group.

The number of hydrolyzable functional groups is 3 or less, and silicon compounds having reactive groups include vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3 -Methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, N-phenyl-3-aminopropyl Trimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, vinyltrimethoxysilane and the like can also be used.

As a silicon compound having a condensable functional group and having the above-mentioned reactive group, vinylsilane triol, 3-glycidoxypropylsilanetriol, 3-glycidoxypropylmethylsilanediol, 3-methacryloxypropylsilanetriol, 3-methacryloxypropylmethylsilanediol, 3-acryloxypropylsilanetriol, 3-mercaptopropylsilanetriol, 3-mercaptopropylmethylsilanediol, N-phenyl-3-aminopropylsilanetriol, N-2- (aminoethyl ) -3-Aminopropylmethylsilanediol and the like can also be used.

Bistrimethoxysilylmethane, bistrimethoxysilylethane, bistrimethoxysilylhexane, etc. can be used as the silicon compound having 3 or less hydrolyzable functional groups at the molecular terminals.

Each of a hydrolyzable functional group or a silicon compound having a condensable functional group (excluding a polysiloxane compound) and a hydrolyzed product of a silicon compound having a hydrolyzable functional group may be used alone or in two types You may mix and use the above.

In preparing the airgel composite of the present embodiment, the silicon compound can include a polysiloxane compound having a hydrolyzable functional group or a condensable functional group. That is, the sol containing the silicon compound can further contain at least one selected from the group consisting of a polysiloxane compound having a reactive group in the molecule and a hydrolysis product of the polysiloxane compound.

The airgel composite of this embodiment has a silica particle derived from alkoxysilane, a polysiloxane compound having a hydrolyzable functional group or a condensable functional group (in the molecule), and a hydrolyzable functional group. Contains at least one compound selected from the group consisting of hydrolysis products of polysiloxane compounds (polysiloxane compounds having hydrolyzable functional groups hydrolyzed) (hereinafter sometimes referred to as “polysiloxane compound groups”). It may be a dried product of a wet gel that is a condensate of sol. That is, the airgel composite of the present embodiment includes an alkoxysilane-derived silica particle, a polysiloxane compound having a hydrolyzable functional group or a condensable functional group (in the molecule), and the hydrolyzable functional group. It may be obtained by drying a wet gel produced from a sol containing at least one selected from the group consisting of hydrolysis products of polysiloxane compounds having groups.

The functional group in the polysiloxane compound group is not particularly limited, but may be a group that reacts with the same functional group or reacts with another functional group. Examples of the hydrolyzable functional group include an alkoxy group. Examples of the condensable functional group include a hydroxyl group, a silanol group, a carboxyl group, and a phenolic hydroxyl group. The hydroxyl group may be contained in a hydroxyl group-containing group such as a hydroxyalkyl group. The polysiloxane compound having a hydrolyzable functional group or a condensable functional group is different from the above-mentioned reactive group (hydrolyzable functional group and condensable functional group). You may further have a functional group which does not correspond to a functional group. These polysiloxane compounds having a functional group and a reactive group may be used alone or in combination of two or more. Among these functional groups and reactive groups, examples of the group that improves the flexibility of the airgel composite include an alkoxy group, a silanol group, and a hydroxyalkyl group. Among these, an alkoxy group and a hydroxyalkyl group Can further improve the compatibility of the sol. Further, from the viewpoint of improving the reactivity of the polysiloxane compound and reducing the thermal conductivity of the airgel composite, the number of carbon atoms of the alkoxy group and hydroxyalkyl group can be 1 to 6, but the flexibility of the airgel composite is not limited. It may be 2 to 4 from the viewpoint of further improving.

Examples of the polysiloxane compound having a hydroxyalkyl group include compounds having a structure represented by the following general formula (A).

In formula (A), R ^1a represents a hydroxyalkyl group, R ^2a represents an alkylene group, R ^3a and R ^4a each independently represents an alkyl group or an aryl group, and n represents an integer of 1 to 50. Here, examples of the aryl group include a phenyl group and a substituted phenyl group. Examples of the substituent of the substituted phenyl group include an alkyl group, a vinyl group, a mercapto group, an amino group, a nitro group, and a cyano group. In formula (A), two R ^{1a s} may be the same or different, and similarly, two R ^{2a s} may be the same or different. In formula (A), two or more R ^{3a s} may be the same or different, and similarly, two or more R ^{4a s} may be the same or different.

By using a wet gel that is a condensate of a sol containing the polysiloxane compound having the above structure (a wet gel produced from the sol), it becomes easier to obtain a flexible airgel with low thermal conductivity. From the same viewpoint, the following features may be satisfied. In formula (A), examples of R ^1a include a hydroxyalkyl group having 1 to 6 carbon atoms, and specific examples include a hydroxyethyl group and a hydroxypropyl group. In the formula (A), examples of R ^2a include an alkylene group having 1 to 6 carbon atoms, and specific examples include an ethylene group and a propylene group. In the formula (A), R ^3a and R ^4a may each independently be an alkyl group having 1 to 6 carbon atoms or a phenyl group. The alkyl group may be a methyl group. In the formula (A), n may be 2 to 30, and may be 5 to 20.

As the polysiloxane compound having the structure represented by the general formula (A), commercially available products can be used. For example, compounds such as X-22-160AS, KF-6001, KF-6002, KF-6003 and the like ( All of which are manufactured by Shin-Etsu Chemical Co., Ltd.) and compounds such as XF42-B0970, Fluid OFOH 702-4% (all manufactured by Momentive).

Examples of the polysiloxane compound having an alkoxy group include compounds having a structure represented by the following general formula (B).

In formula (B), R ^1b represents an alkyl group, an alkoxy group or an aryl group, R ^2b and R ^3b each independently represent an alkoxy group, and R ^4b and R ^5b each independently represent an alkyl group or an aryl group. , M represents an integer of 1 to 50. Here, examples of the aryl group include a phenyl group and a substituted phenyl group. Examples of the substituent of the substituted phenyl group include an alkyl group, a vinyl group, a mercapto group, an amino group, a nitro group, and a cyano group. In the formula (B), two R ^{1b s} may be the same or different, and two R ^{2b s} may be the same or different. Similarly, R ^3b may be the same or different. In the formula (B), when m is an integer of 2 or more, two or more R ^4b may be the same or different, and similarly, two or more R ^5b may be the same. May be different.

By using a wet gel (wet gel generated from the sol), which is a condensate of a sol containing the polysiloxane compound having the structure described above or a hydrolysis product thereof, it becomes easier to obtain a flexible airgel having low thermal conductivity. . From the same viewpoint, the following features may be satisfied. In the formula (B), examples of R ^1b include an alkyl group having 1 to 6 carbon atoms and an alkoxy group having 1 to 6 carbon atoms. Specifically, a methyl group, a methoxy group, and an ethoxy group can be exemplified. Can be mentioned. In the formula (B), R ^2b and R ^3b may each independently be an alkoxy group having 1 to 6 carbon atoms. Examples of the alkoxy group include a methoxy group and an ethoxy group. In the formula (B), R ^4b and R ^5b may each independently be an alkyl group having 1 to 6 carbon atoms or a phenyl group. Examples of the alkyl group include a methyl group. In the formula (B), m can be 2 to 30, and may be 5 to 20.

The polysiloxane compound having the structure represented by the general formula (B) can be obtained by appropriately referring to the production methods reported in, for example, JP-A Nos. 2000-26609 and 2012-233110. Can do.

In addition, since the alkoxy group is hydrolyzed, the polysiloxane compound having an alkoxy group may exist as a hydrolysis product in the sol. The polysiloxane compound having an alkoxy group and the hydrolysis product are It may be mixed. In the polysiloxane compound having an alkoxy group, all of the alkoxy groups in the molecule may be hydrolyzed or partially hydrolyzed.

These polysiloxane compound groups may be used alone or in combination of two or more.

Content of silicon compounds contained in the sol (contents of silicon compounds having hydrolyzable functional groups or condensable functional groups (excluding polysiloxane compounds) contained in the sol because it becomes easier to obtain good reactivity. , And the total content of hydrolysis products of silicon compounds having hydrolyzable functional groups) can be 5 parts by mass or more with respect to 100 parts by mass of the total amount of sol. There may be 12 mass parts or more. Since it becomes easier to obtain good compatibility, the content of the silicon compound group can be 50 parts by mass or less with respect to 100 parts by mass of the total amount of the sol, and may be 30 parts by mass or less. It may be 25 parts by mass or less. That is, the content of the silicon compound group may be 5 to 50 parts by mass, may be 10 to 30 parts by mass, and 12 to 25 parts by mass with respect to 100 parts by mass of the sol. Also good.

When the sol contains a polysiloxane compound group, it becomes easier to obtain good reactivity. Therefore, the content of the polysiloxane compound group contained in the sol (hydrolyzable functional group or condensable functional group) The total content of the polysiloxane compound and the total hydrolysis product content of the polysiloxane compound having a hydrolyzable functional group is 1 part by mass or more with respect to 100 parts by mass of the total amount of the sol. 3 parts by mass or more, 5 parts by mass or more, 7 parts by mass or more, or 10 parts by mass or more. Since it becomes easier to obtain good compatibility, the content of the polysiloxane compound group can be 50 parts by mass or less with respect to 100 parts by mass of the total amount of the sol, and may be 30 parts by mass or less. 15 parts by mass or less. That is, the content of the polysiloxane compound group can be 1 to 50 parts by weight, or 3 to 50 parts by weight, or 5 to 50 parts by weight with respect to 100 parts by weight of the total sol. It may be 7 to 30 parts by mass, 10 to 30 parts by mass, or 10 to 15 parts by mass.

The total of the content of the silicon compound group and the content of the polysiloxane compound group can further easily obtain good reactivity, and therefore can be 5 parts by mass or more with respect to 100 parts by mass of the sol. It may be greater than or equal to 15 parts by weight. Since it becomes easier to obtain good compatibility, the sum of the contents can be 50 parts by mass or less, or 30 parts by mass or less, and 25 parts by mass with respect to 100 parts by mass of the sol. Or less. That is, the total of the above contents can be 5 to 50 parts by mass with respect to 100 parts by mass of the sol, may be 10 to 30 parts by mass, and may be 15 to 25 parts by mass. .

The ratio of the content of the silicon compound group to the content of the polysiloxane compound group (silicon compound group: polysiloxane compound group) can be 0.5: 1 to 4: 1, and 1: 1 to 2 : 1. By setting the ratio of the content of these compounds to 0.5: 1 or more, it becomes easier to obtain good compatibility. By making the content ratio 4: 1 or less, it becomes easier to further suppress the shrinkage of the gel.

The content of silica particles contained in the sol makes it easy to impart an appropriate strength to the airgel composite and makes it easy to obtain an airgel composite having excellent shrinkage resistance during drying. On the other hand, it can be 1 part by mass or more, may be 4 parts by mass or more, and may be 6 parts by mass or more. Since it becomes easy to suppress the solid heat conduction of the silica particles and it becomes easy to obtain an airgel composite excellent in heat insulation, the content of the silica particles can be 20 parts by mass or less, and 15 parts by mass or less. It may be 10 parts by mass or less. That is, the content of silica particles contained in the sol can be 1 to 20 parts by mass with respect to 100 parts by mass of the sol, but may be 4 to 15 parts by mass, or 6 to 10 parts by mass. Part.

Examples of the airgel component in the airgel composite of the present embodiment include the following modes. By adopting these aspects, it becomes easy to control the heat insulating property and flexibility of the airgel composite to a desired level. By employ | adopting each aspect, the airgel composite which has the heat conductivity and compression elastic modulus according to each aspect can be obtained. Therefore, the airgel composite which has the heat insulation according to a use and a softness | flexibility can be provided.

The airgel composite of the present embodiment contains silica particles derived from alkoxysilane and can have a structure represented by the following general formula (1). The airgel component which concerns on this embodiment can have a structure represented by the following general formula (1a) as a structure containing the structure represented by Formula (1). By using the polysiloxane compound having the structure represented by the general formula (A), the structures represented by the formulas (1) and (1a) can be introduced into the skeleton of the airgel component.

In formula (1) and formula (1a), R ¹ and R ² each independently represent an alkyl group or an aryl group, and R ³ and R ⁴ each independently represent an alkylene group. Here, examples of the aryl group include a phenyl group and a substituted phenyl group. Examples of the substituent of the substituted phenyl group include an alkyl group, a vinyl group, a mercapto group, an amino group, a nitro group, and a cyano group. p represents an integer of 1 to 50. In formula (1a), two or more R ^{1 s} may be the same or different, and similarly, two or more R ^{2 s} may be the same or different. In formula (1a), two R ^{3 s} may be the same or different, and similarly, two R ^{4 s} may be the same or different.

By introducing the structure represented by the above formula (1) or formula (1a) into the skeleton of the airgel composite, it becomes a flexible airgel composite with low thermal conductivity. From the same viewpoint, the following features may be satisfied. In formula (1) and formula (1a), R ¹ and R ² may each independently be an alkyl group having 1 to 6 carbon atoms or a phenyl group. Examples of the alkyl group include a methyl group. In formula (1) and formula (1a), R ³ and R ⁴ may each independently be an alkylene group having 1 to 6 carbon atoms. Examples of the alkylene group include an ethylene group and a propylene group. In the formula (1a), p can be 2 to 30, and can be 5 to 20.

The airgel composite of the present embodiment is an airgel composite that includes a silica particle derived from alkoxysilane and has a ladder-type structure including a support portion and a bridge portion, and the bridge portion is represented by the following general formula (2). The airgel composite which has a structure represented by these may be sufficient. By introducing such a ladder structure as an airgel component into the skeleton of the airgel composite, heat resistance and mechanical strength can be improved. By using the polysiloxane compound having the structure represented by the general formula (B), a ladder structure including a bridge portion having the structure represented by the general formula (2) is introduced into the skeleton of the airgel. be able to. In this embodiment, the “ladder structure” has two struts and bridges connecting the struts (having a so-called “ladder” form). It is. In this embodiment, the skeleton of the airgel composite may have a ladder structure, but the airgel composite may partially have a ladder structure.

In formula (2), R ⁵ and R ⁶ each independently represents an alkyl group or an aryl group, and b represents an integer of 1 to 50. Here, examples of the aryl group include a phenyl group and a substituted phenyl group. Examples of the substituent of the substituted phenyl group include an alkyl group, a vinyl group, a mercapto group, an amino group, a nitro group, and a cyano group. In formula (2), when b is an integer of 2 or more, two or more R ^{5 s} may be the same or different, and similarly, two or more R ^{6 s} are the same. Or different.

By introducing the above structure as an airgel component into the skeleton of the airgel complex, for example, it has a structure derived from a conventional ladder-type silsesquioxane (that is, a structure represented by the following general formula (X) An airgel composite having flexibility superior to that of the airgel. Silsesquioxane is a polysiloxane having the above T unit as a structural unit, and has a composition formula: (RSiO _1.5 ) _n . Silsesquioxane can have various skeletal structures such as a cage type, a ladder type, and a random type. As shown by the following general formula (X), in the airgel having a structure derived from a conventional ladder-type silsesquioxane, the structure of the bridge portion is —O—, but in the airgel composite of this embodiment, The structure of the bridge portion is a structure (polysiloxane structure) represented by the general formula (2). The airgel composite of this embodiment may further have a structure derived from silsesquioxane in addition to the structures represented by the general formulas (1) to (3).

In the formula (X), R represents a hydroxy group, an alkyl group or an aryl group.

There are no particular limitations on the structure to be the strut portion and its chain length, and the interval between the structures to be the bridging portions, but from the viewpoint of further improving the heat resistance and mechanical strength, the ladder structure has the following general formula ( It may have a ladder structure represented by 3).

In the formula (3), R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represents an alkyl group or an aryl group, a and c each independently represents an integer of 1 to 3000, and b is 1 to 50 Indicates an integer. Here, examples of the aryl group include a phenyl group and a substituted phenyl group. Examples of the substituent of the substituted phenyl group include an alkyl group, a vinyl group, a mercapto group, an amino group, a nitro group, and a cyano group. In Formula (3), when b is an integer of 2 or more, two or more R ^{5 s} may be the same or different, and similarly, two or more R ^{6 s} may be the same. May be different. In formula (3), when a is an integer of 2 or more, two or more R ^{7 s} may be the same or different. Similarly, when c is an integer of 2 or more, 2 or more R ⁸ may be the same or different from each other.

From the viewpoint of obtaining better flexibility, in formula (2) and formula (3), R ⁵ , R ⁶ , R ⁷ and R ⁸ (however, R ⁷ and R ⁸ are only in formula (3)) are: Each may be independently an alkyl group having 1 to 6 carbon atoms or a phenyl group. Examples of the alkyl group include a methyl group. In the formula (3), a and c can be independently 6 to 2000, and may be 10 to 1000. In the formulas (2) and (3), b can be 2 to 30, and can be 5 to 20.

The airgel composite of the present embodiment can have a structure represented by the following general formula (4). The airgel composite of the present embodiment contains silica particles and can have a structure represented by the following general formula (4).

In formula (4), R ⁹ represents an alkyl group. Examples of the alkyl group include alkyl groups having 1 to 6 carbon atoms, and specific examples include a methyl group.

The airgel composite of the present embodiment can have a structure represented by the following general formula (5). The airgel composite of the present embodiment contains silica particles and can have a structure represented by the following general formula (5).

In formula (5), R ¹⁰ and R ¹¹ each independently represent an alkyl group. Examples of the alkyl group include alkyl groups having 1 to 6 carbon atoms, and specific examples include a methyl group.

The airgel composite of this embodiment can have a structure represented by the following general formula (6). The airgel composite of the present embodiment contains silica particles and can have a structure represented by the following general formula (6).

In the formula (6), R ¹² represents an alkylene group. Examples of the alkylene group include an alkylene group having 1 to 10 carbon atoms, and specific examples include an ethylene group and a hexylene group.

<Physical properties of airgel composite>
[Thermal conductivity]
In the airgel composite of the present embodiment, the thermal conductivity at 25 ° C. under atmospheric pressure can be 0.03 W / m · K or less, but may be 0.025 W / m · K or less, or It may be 0.02 W / m · K or less. When the thermal conductivity is 0.03 W / m · K or less, it is possible to obtain a heat insulating property higher than that of the polyurethane foam which is a high performance heat insulating material. The lower limit value of the thermal conductivity is not particularly limited, but can be set to 0.01 W / m · K, for example.

Thermal conductivity can be measured by a steady method. The thermal conductivity can be measured using, for example, a steady-state thermal conductivity measuring device “HFM436 Lambda” (manufactured by NETZSCH, product name, HFM436 Lambda is a registered trademark). The outline of the measurement method of the thermal conductivity using the steady method thermal conductivity measuring device is as follows.

(Preparation of measurement sample)
The airgel composite is processed into a size of 150 mm × 150 mm × 100 mm using a blade having a blade angle of about 20 to 25 degrees to obtain a measurement sample. In addition, although the recommended sample size in HFM436Lambda is 300 mm × 300 mm × 100 mm, the thermal conductivity when measured with the above sample size is the same value as the thermal conductivity when measured with the recommended sample size. Confirmed. Next, in order to ensure parallelism of the surface, the measurement sample is shaped with a sandpaper of # 1500 or more as necessary. Then, before the thermal conductivity measurement, the measurement sample is dried at 100 ° C. for 30 minutes under atmospheric pressure using a constant temperature dryer “DVS402” (manufactured by Yamato Scientific Co., Ltd., product name). The measurement sample is then transferred into a desiccator and cooled to 25 ° C. Thereby, the measurement sample for thermal conductivity measurement is obtained.

(Measuring method)
The measurement conditions are an atmospheric pressure and an average temperature of 25 ° C. The measurement sample obtained as described above is sandwiched between the upper and lower heaters with a load of 0.3 MPa, the temperature difference ΔT is set to 20 ° C., and the guard sample is adjusted so as to obtain a one-dimensional heat flow. Measure upper surface temperature, lower surface temperature, etc. And the thermal resistance _RS of a measurement sample is calculated | required from following Formula.
R _S = N ((T _U −T _L ) / Q) −R _O
Wherein, T _U represents a measurement sample top surface temperature, T _L represents the measurement sample lower surface temperature, R _O represents the thermal contact resistance of the upper and lower interfaces, Q is shows the heat flux meter output. N is a proportionality coefficient, and is obtained in advance using a calibration sample.

From the obtained thermal resistance _RS , the thermal conductivity λ of the measurement sample is obtained from the following equation.
λ = d / R _S
In formula, d shows the thickness of a measurement sample.

[Compressive modulus]
In the airgel composite of the present embodiment, the compression modulus at 25 ° C. can be 3 MPa or less, but may be 2 MPa or less, 1 MPa or less, or 0.5 MPa or less. Good. When the compression elastic modulus is 3 MPa or less, it becomes easy to obtain an airgel composite having excellent handleability. In addition, the lower limit value of the compression elastic modulus is not particularly limited, but may be 0.05 MPa, for example.

[Deformation recovery rate]
In the airgel composite of this embodiment, the deformation recovery rate at 25 ° C. can be 90% or more, but may be 94% or more, or 98% or more. When the deformation recovery rate is 90% or more, it becomes easier to obtain excellent strength, excellent flexibility for deformation, and the like. Note that the upper limit value of the deformation recovery rate is not particularly limited, but may be, for example, 100% or 99%.

[Maximum compression deformation rate]
In the airgel composite of this embodiment, the maximum compressive deformation rate at 25 ° C. can be 80% or more, but may be 83% or more, or 86% or more. When the maximum compressive deformation rate is 80% or more, it becomes easier to obtain excellent strength, excellent flexibility for deformation, and the like. The upper limit value of the maximum compression deformation rate is not particularly limited, but can be 90%, for example.

These compression elastic modulus, deformation recovery rate, and maximum compression deformation rate can be measured using a small desktop tester “EZTest” (manufactured by Shimadzu Corporation, product name). The outline of a method for measuring the compression modulus and the like using a small tabletop testing machine is as follows.

(Preparation of measurement sample)
Using a blade with a blade angle of about 20 to 25 degrees, the airgel composite is processed into a 7.0 mm square cube (die shape) to obtain a measurement sample. Next, in order to ensure parallelism of the surface, the measurement sample is shaped with a sandpaper of # 1500 or more as necessary. Before measurement, the measurement sample is dried at 100 ° C. for 30 minutes under atmospheric pressure using a constant temperature dryer “DVS402” (manufactured by Yamato Scientific Co., Ltd., product name). The measurement sample is then transferred into a desiccator and cooled to 25 ° C. Thereby, a measurement sample for measuring the compression elastic modulus, deformation recovery rate, and maximum compression deformation rate is obtained.

(Measuring method)
A 500N load cell is used. A stainless upper platen (φ20 mm) and a lower platen plate (φ118 mm) are used as a compression measurement jig. A measurement sample is set between these jigs, compressed at a speed of 1 mm / min, and the displacement of the measurement sample size at 25 ° C. is measured. The measurement is terminated when a load exceeding 500 N is applied or when the measurement sample is destroyed. Here, the compressive strain ε can be obtained from the following equation.
ε = Δd / d1
In the formula, Δd represents the displacement (mm) of the thickness of the measurement sample due to the load, and d1 represents the thickness (mm) of the measurement sample before the load is applied.
The compressive stress σ (MPa) can be obtained from the following equation.
σ = F / A
In the formula, F represents the compressive force (N), and A represents the cross-sectional area (mm ² ) of the measurement sample before applying a load.

The compression elastic modulus E (MPa) can be obtained from the following equation in the compression force range of 0.1 to 0.2 N, for example.
E = (σ ₂ −σ ₁ ) / (ε ₂ −ε ₁ )
In the formula, σ ₁ indicates a compressive stress (MPa) measured at a compressive force of 0.1 N, σ ₂ indicates a compressive stress (MPa) measured at a compressive force of 0.2 N, and ε ₁ indicates a compressive stress. The compressive strain measured at σ ₁ is shown, and ε ₂ shows the compressive strain measured at the compressive stress σ ₂ .

On the other hand, the deformation recovery rate and the maximum compressive deformation rate are d1, the thickness of the measurement sample before applying the load, d2, the thickness of the measurement sample at the time when the maximum load of 500 N is applied, or the measurement sample is destroyed, and the load is removed. Then, the thickness of the measurement sample can be calculated according to the following formula, where d3 is the thickness.
Deformation recovery rate = (d3-d2) / (d1-d2) × 100
Maximum compression deformation rate = (d1−d2) / d1 × 100

In addition, these thermal conductivity, compression elastic modulus, deformation recovery rate, and maximum compression deformation rate can be appropriately adjusted by changing the production conditions, raw materials, etc. of the airgel composite described later.

[Density and porosity]
In the airgel composite of the present embodiment, the size of the pores 3, that is, the average pore diameter can be 5 to 1000 nm, but may be 25 to 500 nm. When the average pore diameter is 5 nm or more, an airgel composite excellent in flexibility can be easily obtained, and when it is 1000 nm or less, an airgel composite excellent in heat insulation can be easily obtained.

In airgel composite of this embodiment, the density may be 0.05 ~ 0.25g / cm ³ at 25 ° C., or may be 0.1 ~ 0.2g / cm ^3. When the density is 0.05 g / cm ³ or more, more excellent strength and flexibility can be obtained, and when it is 0.25 g / cm ³ or less, more excellent heat insulation can be obtained. it can.

In the airgel composite of this embodiment, the porosity at 25 ° C. can be 85 to 95%, but it may be 87 to 93%. When the porosity is 85% or more, more excellent heat insulating properties can be obtained, and when it is 95% or less, more excellent strength and flexibility can be obtained.

Regarding the airgel composite, the average pore diameter, density and porosity of pores (through holes) continuous in a three-dimensional network can be measured by a mercury intrusion method according to DIN 66133. As a measuring device, for example, Autopore IV9520 (manufactured by Shimadzu Corporation, product name) can be used.

<Method for producing airgel composite>
Next, the manufacturing method of an airgel composite is demonstrated. Although the manufacturing method of an airgel composite is not specifically limited, For example, it can manufacture with the following method.

That is, the airgel composite of the present embodiment was obtained in the sol generation step, the wet gel generation step in which the sol obtained in the sol generation step was gelled and then aged to obtain a wet gel, and the wet gel generation step. The wet gel can be produced by a production method mainly comprising a step of washing and (if necessary) replacing the solvent with a solvent and a drying step of drying the wet gel after washing and solvent substitution. The “sol” is a state before the gelation reaction occurs, and in the present embodiment, the silicon compound (silicon compound group and / or polysiloxane compound group) and silica particles are contained in a solvent. It means a dissolved or dispersed state. The “wet gel” means a gel solid in a wet state that contains a liquid medium but does not have fluidity.

Hereafter, each process of the manufacturing method of the airgel composite of this embodiment is demonstrated.

(Sol generation process)
A sol production | generation process is a process of mixing the above-mentioned silicon compound and the solvent containing a silica particle or a silica particle, and making it hydrolyze and producing | generating a sol. In this step, an acid catalyst may be further added to the solvent in order to promote the hydrolysis reaction. Further, as disclosed in Japanese Patent No. 5250900, a surfactant, a thermohydrolyzable compound, or the like can be added to the solvent. Furthermore, components such as carbon graphite, an aluminum compound, a magnesium compound, a silver compound, and a titanium compound may be added to the solvent for the purpose of suppressing heat radiation.

As the solvent, for example, water or a mixed solution of water and alcohols can be used. Examples of alcohols include methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-butanol, and t-butanol. Among these, alcohols having a low surface tension and a low boiling point in terms of reducing the interfacial tension with the gel wall include methanol, ethanol, 2-propanol and the like. You may use these individually or in mixture of 2 or more types.

For example, when alcohols are used as the solvent, the amount of alcohols can be 4 to 8 moles with respect to 1 mole of the total amount of silicon compounds (silicon compound group and polysiloxane compound group). 5 or 4.5 to 6 moles. By making the amount of alcohols 4 mol or more, it becomes easier to obtain good compatibility, and by making the amount 8 mol or less, it becomes easier to suppress gel shrinkage.

Examples of the acid catalyst include hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, hypophosphorous acid, bromic acid, chloric acid, chlorous acid, hypochlorous acid, and other inorganic acids; acidic phosphoric acid Acidic phosphates such as aluminum, acidic magnesium phosphate and acidic zinc phosphate; organic carboxylic acids such as acetic acid, formic acid, propionic acid, oxalic acid, malonic acid, succinic acid, citric acid, malic acid, adipic acid and azelaic acid Etc. Among these, an organic carboxylic acid is mentioned as an acid catalyst which improves the water resistance of the airgel composite obtained more. Examples of the organic carboxylic acids include acetic acid, but may be formic acid, propionic acid, oxalic acid, malonic acid and the like. You may use these individually or in mixture of 2 or more types.

By using an acid catalyst, the hydrolysis reaction of the silicon compound is promoted, and a sol can be obtained in a shorter time.

The addition amount of the acid catalyst can be 0.001 to 0.1 parts by mass with respect to 100 parts by mass of the total amount of the silicon compound.

As the surfactant, a nonionic surfactant, an ionic surfactant, or the like can be used. You may use these individually or in mixture of 2 or more types.

As the nonionic surfactant, for example, a compound containing a hydrophilic part such as polyoxyethylene and a hydrophobic part mainly composed of an alkyl group, or a compound containing a hydrophilic part such as polyoxypropylene can be used. Examples of the compound containing a hydrophilic part such as polyoxyethylene and a hydrophobic part mainly composed of an alkyl group include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene alkyl ether and the like. Examples of the compound having a hydrophilic portion such as polyoxypropylene include polyoxypropylene alkyl ether, a block copolymer of polyoxyethylene and polyoxypropylene, and the like.

As the ionic surfactant, a cationic surfactant, an anionic surfactant, an amphoteric surfactant, or the like can be used. Examples of the cationic surfactant include cetyltrimethylammonium bromide and cetyltrimethylammonium chloride. Examples of the anionic surfactant include sodium dodecyl sulfonate. Examples of amphoteric surfactants include amino acid surfactants, betaine surfactants, and amine oxide surfactants. Examples of amino acid surfactants include acyl glutamic acid. Examples of betaine surfactants include lauryldimethylaminoacetic acid betaine and stearyldimethylaminoacetic acid betaine. Examples of the amine oxide surfactant include lauryl dimethylamine oxide.

These surfactants have the effect of reducing the difference in chemical affinity between the solvent in the reaction system and the growing siloxane polymer and suppressing phase separation in the wet gel formation process described later. It is considered to be.

The amount of surfactant added depends on the type of surfactant or the type and amount of silicon compound (silicon compound group and polysiloxane compound group). For example, the total amount of silicon compound is 100 parts by mass. The amount may be 1 to 100 parts by mass, and may be 5 to 60 parts by mass.

The thermohydrolyzable compound is considered to generate a base catalyst by thermal hydrolysis to make the reaction solution basic and to promote the sol-gel reaction in the wet gel generation process described later. Accordingly, the thermohydrolyzable compound is not particularly limited as long as it can make the reaction solution basic after hydrolysis. For example, urea; formamide, N-methylformamide, N, N-dimethylformamide, acetamide And acid amides such as N-methylacetamide and N, N-dimethylacetamide; and cyclic nitrogen compounds such as hexamethylenetetramine. Among these, urea is particularly easy to obtain the above-mentioned promoting effect.

The addition amount of the thermohydrolyzable compound is not particularly limited as long as it can sufficiently promote the sol-gel reaction in the wet gel generation step described later. For example, when urea is used as the thermally hydrolyzable compound, the amount added can be 1 to 200 parts by mass with respect to 100 parts by mass of the total amount of the silicon compound. The added amount may be 2 to 150 parts by mass. By making the addition amount 1 mass part or more, it becomes easier to obtain good reactivity. By making the addition amount 200 parts by mass or less, it becomes easier to suppress the precipitation of crystals and the decrease in gel density.

The hydrolysis in the sol production step depends on the type and amount of silicon compound, polysiloxane compound, silica particles, acid catalyst, surfactant, etc. in the mixed solution, but for example, in a temperature environment of 20 to 60 ° C. For 10 minutes to 24 hours, or in a temperature environment of 50 to 60 ° C. for 5 minutes to 8 hours. Thereby, the hydrolyzable functional group in a silicon compound and a polysiloxane compound is fully hydrolyzed, and the hydrolysis product of a silicon compound and the hydrolysis product of a polysiloxane compound can be obtained more reliably.

When adding a thermohydrolyzable compound in the solvent, the temperature environment of the sol generation step may be adjusted to a temperature that suppresses hydrolysis of the thermohydrolyzable compound and suppresses gelation of the sol. The temperature at this time may be any temperature as long as the hydrolysis of the thermally hydrolyzable compound can be suppressed. For example, when urea is used as the thermally hydrolyzable compound, the temperature environment of the sol production step can be 0 to 40 ° C., but may be 10 to 30 ° C.

(Wet gel production process)
The wet gel generation step is a step in which the sol obtained in the sol generation step is gelled and then aged to obtain a wet gel. In this step, a base catalyst can be used to promote gelation.

Base catalysts include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, and cesium hydroxide; ammonium compounds such as ammonium hydroxide, ammonium fluoride, ammonium chloride, and ammonium bromide; sodium metaphosphate Basic sodium phosphates such as sodium pyrophosphate and sodium polyphosphate; allylamine, diallylamine, triallylamine, isopropylamine, diisopropylamine, ethylamine, diethylamine, triethylamine, 2-ethylhexylamine, 3-ethoxypropylamine, diisobutylamine, 3 -(Diethylamino) propylamine, di-2-ethylhexylamine, 3- (dibutylamino) propylamine, tetramethylethylenediamine, t-butylamine, sec Aliphatic amines such as butylamine, propylamine, 3- (methylamino) propylamine, 3- (dimethylamino) propylamine, 3-methoxyamine, dimethylethanolamine, methyldiethanolamine, diethanolamine, triethanolamine; morpholine, N -Nitrogen-containing heterocyclic compounds such as methylmorpholine, 2-methylmorpholine, piperazine and derivatives thereof, piperidine and derivatives thereof, imidazole and derivatives thereof, and the like. Among these, ammonium hydroxide (ammonia water) is excellent in that it has high volatility and does not easily remain in the airgel composite after drying, so that it is difficult to impair water resistance, and further, it is economical. You may use said base catalyst individually or in mixture of 2 or more types.

By using a base catalyst, the dehydration condensation reaction or dealcoholization condensation reaction of the silicon compound (polysiloxane compound group and silicon compound group) and silica particles in the sol can be promoted, and the gelation of the sol can be performed in a shorter time. It can be carried out. Thereby, a wet gel with higher strength (rigidity) can be obtained. In particular, ammonia has high volatility and hardly remains in the airgel composite. Therefore, by using ammonia as a base catalyst, an airgel composite having better water resistance can be obtained.

The addition amount of the base catalyst can be 0.5 to 5 parts by mass with respect to 100 parts by mass of the total amount of silicon compounds (polysiloxane compound group and silicon compound group), but it can be 1 to 4 parts by mass. Good. By making the addition amount of the base catalyst 0.5 parts by mass or more, gelation can be performed in a shorter time. The fall of water resistance can be suppressed more by making the addition amount of a base catalyst into 5 mass parts or less.

The gelation of the sol in the wet gel generation step may be performed in a sealed container so that the solvent and the base catalyst do not volatilize. The gelation temperature can be, for example, 30 to 90 ° C., but may be 40 to 80 ° C. By setting the gelation temperature to 30 ° C. or higher, gelation can be performed in a shorter time, and a wet gel with higher strength (rigidity) can be obtained. Moreover, since it becomes easy to suppress volatilization of a solvent (especially alcohol) by making gelation temperature into 90 degrees C or less, it can gelatinize, suppressing volume shrinkage.

The aging in the wet gel generation step may be performed in a sealed container so that the solvent and the base catalyst do not volatilize. By aging, the components of the wet gel are strongly bonded, and as a result, a wet gel having a high strength (rigidity) sufficient to suppress shrinkage during drying can be obtained. The aging temperature can be, for example, 30 to 90 ° C., but may be 40 to 80 ° C. By setting the aging temperature to 30 ° C. or higher, a wet gel with higher strength (rigidity) can be obtained, and by setting the aging temperature to 90 ° C. or lower, volatilization of the solvent (especially alcohols) can be easily suppressed. Therefore, it can be gelled while suppressing volume shrinkage.

In addition, since it is often difficult to determine the end point of gelation of the sol, gelation of the sol and subsequent aging may be performed in a series of operations.

Although the gelation time and the aging time differ depending on the gelation temperature and the aging temperature, in the present embodiment, since the sol contains silica particles, the gelation time is particularly compared with the conventional method for producing an airgel. Can be shortened. The reason for this is presumed that the silanol groups and / or reactive groups other than the silanol groups of the silicon compound group and the polysiloxane compound group in the sol form hydrogen bonds or chemical bonds with the silanol groups of the silica particles. To do. The gelation time can be, for example, 10 to 120 minutes, but may be 20 to 90 minutes. By setting the gelation time to 10 minutes or more, it becomes easy to obtain a homogeneous wet gel, and by setting it to 120 minutes or less, the drying process can be simplified from the washing and solvent replacement process described later. Note that the total time of the gelation time and the aging time in the entire gelation and aging process can be, for example, 4 to 480 hours, but may be 6 to 120 hours. By setting the total gelation time and aging time to 4 hours or more, a wet gel with higher strength (rigidity) can be obtained, and by setting it to 480 hours or less, the effect of aging can be more easily maintained.

In order to decrease the density of the obtained airgel composite or increase the average pore diameter, the gelation temperature and the aging temperature are increased within the above range, or the total time of the gelation time and the aging time is increased within the above range. May be. Further, in order to increase the density of the obtained airgel composite or to reduce the average pore diameter, the gelation temperature and the aging temperature are reduced within the above range, or the total time of the gelation time and the aging time is within the above range. It can be shortened.

(Washing and solvent replacement process)
The washing and solvent replacement step is a step of washing the wet gel obtained by the wet gel generation step (washing step), and a step of replacing the washing liquid in the wet gel with a solvent suitable for the drying conditions (the drying step described later). It is a process which has (solvent substitution process). The washing and solvent replacement step can be performed in a form in which only the solvent replacement step is performed without performing the step of washing the wet gel, but the impurities such as unreacted substances and by-products in the wet gel are reduced, and more From the viewpoint of enabling the production of a highly pure airgel composite, the wet gel may be washed. In the present embodiment, since the silica particles are contained in the gel, the solvent replacement step is not necessarily essential as described later.

In the washing step, the wet gel obtained in the wet gel production step is washed. The washing can be repeatedly performed using, for example, water or an organic solvent. At this time, washing efficiency can be improved by heating.

Organic solvents include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetone, methyl ethyl ketone, 1,2-dimethoxyethane, acetonitrile, hexane, toluene, diethyl ether, chloroform, ethyl acetate, tetrahydrofuran, methylene chloride , N, N-dimethylformamide, dimethyl sulfoxide, acetic acid, formic acid, and other various organic solvents can be used. You may use said organic solvent individually or in mixture of 2 or more types.

In the solvent replacement step described later, a low surface tension solvent can be used in order to suppress gel shrinkage due to drying. However, low surface tension solvents generally have very low mutual solubility with water. Therefore, when using a low surface tension solvent in the solvent replacement step, examples of the organic solvent used in the washing step include hydrophilic organic solvents having high mutual solubility in both water and a low surface tension solvent. Note that the hydrophilic organic solvent used in the washing step can serve as a preliminary replacement for the solvent replacement step. Among the above organic solvents, examples of hydrophilic organic solvents include methanol, ethanol, 2-propanol, acetone, and methyl ethyl ketone. From the economical point of view, methanol, ethanol, or methyl ethyl ketone may be used.

The amount of water or organic solvent used in the washing step can be an amount that can be sufficiently washed by replacing the solvent in the wet gel. The amount can be 3 to 10 times the volume of the wet gel. The washing can be repeated until the moisture content in the wet gel after washing is 10% by mass or less with respect to the silica mass.

The temperature environment in the washing step can be a temperature not higher than the boiling point of the solvent used for washing. For example, when methanol is used, the temperature can be raised to about 30 to 60 ° C.

In the solvent replacement step, the solvent of the washed wet gel is replaced with a predetermined replacement solvent in order to suppress shrinkage in the drying step described later. At this time, the replacement efficiency can be improved by heating. Specific examples of the solvent for substitution include a low surface tension solvent described later in the drying step when drying is performed under atmospheric pressure at a temperature lower than the critical point of the solvent used for drying. On the other hand, when performing supercritical drying, examples of the substitution solvent include ethanol, methanol, 2-propanol, dichlorodifluoromethane, carbon dioxide, and the like, or a mixture of two or more thereof.

Examples of the low surface tension solvent include a solvent having a surface tension at 20 ° C. of 30 mN / m or less. The surface tension may be 25 mN / m or less, or 20 mN / m or less. Examples of the low surface tension solvent include pentane (15.5), hexane (18.4), heptane (20.2), octane (21.7), 2-methylpentane (17.4), 3- Aliphatic hydrocarbons such as methylpentane (18.1), 2-methylhexane (19.3), cyclopentane (22.6), cyclohexane (25.2), 1-pentene (16.0); Aromatic hydrocarbons such as (28.9), toluene (28.5), m-xylene (28.7), p-xylene (28.3); dichloromethane (27.9), chloroform (27.2) ), Carbon tetrachloride (26.9), 1-chloropropane (21.8), 2-chloropropane (18.1) and other halogenated hydrocarbons; ethyl ether (17.1), propyl ether (20.5) ), Isop Ethers such as pyrether (17.7), butyl ethyl ether (20.8), 1,2-dimethoxyethane (24.6); acetone (23.3), methyl ethyl ketone (24.6), methyl propyl ketone (25.1), ketones such as diethyl ketone (25.3); methyl acetate (24.8), ethyl acetate (23.8), propyl acetate (24.3), isopropyl acetate (21.2), Examples include esters such as isobutyl acetate (23.7) and ethyl butyrate (24.6) (inside the surface tension is indicated at 20 ° C., and the unit is [mN / m]). Among these, aliphatic hydrocarbons (hexane, heptane, etc.) have a low surface tension and an excellent working environment. Among these, by using a hydrophilic organic solvent such as acetone, methyl ethyl ketone, 1,2-dimethoxyethane, it can be used as the organic solvent in the washing step. Among these, a solvent having a boiling point at normal pressure of 100 ° C. or less may be used because it is easy to dry in the drying step described later. You may use said solvent individually or in mixture of 2 or more types.

The amount of the solvent used in the solvent replacement step can be an amount that can sufficiently replace the solvent in the wet gel after washing. The amount can be 3 to 10 times the volume of the wet gel.

The temperature environment in the solvent replacement step can be a temperature not higher than the boiling point of the solvent used for the replacement. For example, when heptane is used, the temperature can be increased to about 30 to 60 ° C.

In this embodiment, since the silica particles are contained in the gel, the solvent replacement step is not necessarily essential as described above. The inferred mechanism is as follows. That is, conventionally, in order to suppress shrinkage in the drying process, the solvent of the wet gel is replaced with a predetermined replacement solvent (a low surface tension solvent), but in this embodiment, the silica particles are in a three-dimensional network shape. By functioning as a skeleton support, the skeleton is supported, and the shrinkage of the gel in the drying step is suppressed. Therefore, it is considered that the gel can be directly subjected to the drying step without replacing the solvent used for washing. Thus, in this embodiment, the drying process can be simplified from the washing and solvent replacement process. However, this embodiment does not exclude performing the solvent substitution step at all.

(Drying process)
In the drying step, the wet gel washed and solvent-substituted (if necessary) is dried as described above. Thereby, an airgel composite can be finally obtained.

The drying method is not particularly limited, and known atmospheric pressure drying, supercritical drying, or freeze drying can be used. Among these, atmospheric drying or supercritical drying can be used from the viewpoint of easy production of a low-density airgel composite. Further, from the viewpoint that production is possible at low cost, atmospheric pressure drying can be used. In the present embodiment, the normal pressure means 0.1 MPa (atmospheric pressure).

The airgel composite of the present embodiment can be obtained by drying a wet gel that has been washed and solvent-substituted (if necessary) at a temperature below the critical point of the solvent used for drying under atmospheric pressure. The drying temperature varies depending on the type of the substituted solvent (the solvent used for washing when solvent substitution is not performed). In particular, in view of the fact that drying at a high temperature increases the evaporation rate of the solvent and may cause large cracks in the gel, the drying temperature can be 20 to 150 ° C, even if it is 60 to 120 ° C. Good. The drying time varies depending on the wet gel volume and the drying temperature, but can be 4 to 120 hours. In the present embodiment, it is also included in the atmospheric pressure drying that the drying is accelerated by applying a pressure less than the critical point within a range not inhibiting the productivity.

The airgel composite of the present embodiment can also be obtained by supercritical drying a wet gel that has been washed and (if necessary) solvent-substituted. Supercritical drying can be performed by a known method. Examples of the supercritical drying method include a method of removing the solvent at a temperature and pressure higher than the critical point of the solvent contained in the wet gel. Alternatively, as a method for supercritical drying, all or part of the solvent contained in the wet gel is obtained by immersing the wet gel in liquefied carbon dioxide, for example, at about 20 to 25 ° C. and about 5 to 20 MPa. And carbon dioxide having a lower critical point than that of the solvent, and then removing carbon dioxide alone or a mixture of carbon dioxide and the solvent.

The airgel composite obtained by such normal pressure drying or supercritical drying may be further dried at 105 to 200 ° C. for about 0.5 to 2 hours under normal pressure. This makes it easier to obtain an airgel composite having a low density and having small pores. Additional drying may be performed at 150 to 200 ° C. under normal pressure.

<Support member with airgel composite>
The support member with an airgel composite of the present embodiment includes the airgel composite described so far and a support member that supports the airgel composite. Such a support member with an airgel composite can exhibit high heat insulation and excellent flexibility.

Examples of the support member include a film-like support member, a sheet-like support member, a foil-like support member, and a porous support member.

The film-like support member is obtained by molding a polymer raw material into a thin film, and examples thereof include organic films such as PET and polyimide, glass films, and the like (including metal vapor-deposited films).

The sheet-like support member is formed by molding an organic, inorganic or metal fiber material, and examples thereof include paper, nonwoven fabric (including glass mat), organic fiber cloth, and glass cloth.

The foil-like support member is a metal raw material formed into a thin film, and examples thereof include aluminum foil and copper foil.

The porous support member has a porous structure using organic, inorganic or metal as a raw material, and is made of a porous organic material (for example, polyurethane foam), a porous inorganic material (for example, zeolite sheet), or a porous metal material. (For example, a porous metal sheet, a porous aluminum sheet) and the like.

The support member with the airgel composite can be manufactured, for example, as follows. First, a sol is prepared according to the sol generation process described above. After applying this onto the support member using a film applicator or the like, or impregnating the support member with the film applicator, a film-like support member with a wet gel is obtained according to the wet gel generation step described above. The film-like support member with wet gel thus obtained is subjected to washing and solvent substitution according to the above-described washing and solvent substitution step, and further dried according to the above-described drying step, thereby supporting the airgel composite. A member can be obtained.

The thickness of the airgel composite formed on the film-like support member or the foil-like support member can be 1 to 200 μm, but may be 10 to 100 μm, or 30 to 80 μm. When the thickness is 1 μm or more, it is easy to obtain good heat insulating properties, and when it is 200 μm or less, flexibility is easily obtained.

The airgel composite of the present embodiment described as described above has excellent heat insulating properties and flexibility, which has been difficult to achieve with conventional airgel, by containing an airgel component and silica particles. The particularly excellent flexibility made it possible to form an airgel composite layer on a film-like support member and a foil-like support member, which had been difficult to achieve in the past. Therefore, the support member with an airgel composite of the present embodiment has high heat insulating properties and excellent flexibility. In addition, also in the aspect which impregnates a sheet-like support member and a porous support member with sol, it is possible to suppress the powder falling of an airgel composite at the time of handling after drying.

Because of such advantages, the airgel composite and the support member with the airgel composite of the present embodiment can be applied to a use as a heat insulating material in an architectural field, an automotive field, a home appliance, a semiconductor field, an industrial facility, and the like. Moreover, the airgel composite of this embodiment can be used as a coating additive, cosmetics, antiblocking agent, catalyst carrier, etc., in addition to its use as a heat insulating material.

<Insulation material>
The heat insulating material of the present embodiment includes the airgel composite described so far, and has high heat insulating properties and excellent flexibility. In addition, the airgel composite obtained by the manufacturing method of the said airgel composite can be made into a heat insulating material as it is (processed into a predetermined shape as needed).

Next, the present disclosure will be described in more detail by the following examples, but these examples do not limit the present disclosure in any way.

Example 1
[Wet gel, airgel composite]
60.0 parts by mass of methyltrimethoxysilane LS-530 (manufactured by Shin-Etsu Chemical Co., Ltd., product name: hereinafter abbreviated as “MTMS”) and dimethyldimethoxysilane LS-520 (manufactured by Shin-Etsu Chemical Co., Ltd., product) Name: 40.0 parts by mass of “DMDMS”) and PL-2L as a silica particle-containing raw material (details of PL-2L are described in Table 1. The same applies to the silica particle-containing raw material). 0 parts by mass, 40.0 parts by mass of water and 80.0 parts by mass of methanol were mixed, and 0.10 parts by mass of acetic acid as an acid catalyst was added thereto, and reacted at 25 ° C. for 2 hours to obtain sol 1. 40.0 parts by mass of 5% strength aqueous ammonia as a base catalyst was added to the obtained sol 1, gelled at 60 ° C., and then aged at 80 ° C. for 24 hours to obtain wet gel 1.

Thereafter, the obtained wet gel 1 was immersed in 2500.0 parts by mass of methanol and washed at 60 ° C. for 12 hours. This washing operation was performed 3 times while exchanging with fresh methanol. Next, the washed wet gel was immersed in 2500.0 parts by mass of heptane, which is a low surface tension solvent, and solvent substitution was performed at 60 ° C. for 12 hours. This solvent replacement operation was performed three times while exchanging with new heptane. The washed and solvent-substituted wet gel is dried at 40 ° C. for 96 hours under normal pressure, and then further dried at 150 ° C. for 2 hours, whereby the structures represented by the above general formulas (4) and (5) are obtained. The airgel composite 1 which has this was obtained.

[Support member with airgel composite]
(Film-like support member with airgel composite)
A film applicator (manufactured by Tester Sangyo Co., Ltd., PI-1210) is prepared by making the sol 1 into a polyethylene terephthalate film (length) 300 mm × (width) 270 mm × (thickness) 12 μm so that the thickness after gelation becomes 40 μm. After being gelled at 60 ° C. for 3 hours, it was aged at 80 ° C. for 24 hours to obtain a film-like support member 1 with a wet gel.

Thereafter, the obtained film-like support member 1 with wet gel was immersed in 100 mL of methanol and washed at 60 ° C. for 2 hours. Next, the washed film-like support member with wet gel was immersed in 100 mL of methyl ethyl ketone, and the solvent was replaced at 60 ° C. for 2 hours. This solvent replacement operation was performed twice while exchanging with new methyl ethyl ketone. The washed and solvent-substituted film-like support member with a wet gel was dried at 120 ° C. for 6 hours under normal pressure to obtain a film-like support member 1 with an airgel composite.

(Sheet-like support member with airgel composite)
The above sol 1 is impregnated into an E glass cloth of (length) 300 mm × (width) 270 mm × (thickness) 100 μm so that the thickness of the sheet-like support member after gelation becomes 120 μm, and gelled at 60 ° C. for 3 hours. After that, it was aged at 80 ° C. for 24 hours to obtain a sheet-like support member 1 with a wet gel.

Thereafter, the obtained sheet-like support member 1 with wet gel was immersed in 300 mL of methanol and washed at 60 ° C. for 2 hours. Next, the washed sheet-like support member with wet gel was immersed in 300 mL of methyl ethyl ketone, and the solvent was replaced at 60 ° C. for 2 hours. This solvent replacement operation was performed twice while exchanging with new methyl ethyl ketone. The washed and solvent-substituted sheet-like support member with a wet gel was dried at 120 ° C. for 8 hours under normal pressure to obtain a sheet-like support member 1 with an airgel composite.

(Foil-like support member with airgel composite)
The sol 1 was applied to an aluminum foil of (length) 300 mm × (width) 270 mm × (thickness) 12 μm using a film applicator so that the thickness after gelation was 40 μm, and gelled at 60 ° C. for 3 hours. Then, it was aged at 80 ° C. for 24 hours to obtain a foil-like support member 1 with a wet gel.

Thereafter, the obtained foil-like support member 1 with wet gel was immersed in 100 mL of methanol and washed at 60 ° C. for 2 hours. Next, the washed foil-like support member with wet gel was immersed in 100 mL of methyl ethyl ketone, and solvent substitution was performed at 60 ° C. for 2 hours. This solvent replacement operation was performed twice while exchanging with new methyl ethyl ketone. The washed and solvent-substituted foil-like support member with a wet gel was dried at 120 ° C. for 6 hours under normal pressure to obtain a foil-like support member 1 with an airgel composite.

(Porous support member with airgel composite)
The above sol 1 is impregnated into a flexible urethane foam of (length) 300 mm × (width) 270 mm × (thickness) 10 mm so that the thickness of the porous support member after gelation becomes 10 mm, and gelled at 60 ° C. for 3 hours. After that, it was aged at 80 ° C. for 24 hours to obtain a porous support member 1 with a wet gel.

Thereafter, the obtained porous support member 1 with wet gel was immersed in 300 mL of methanol and washed at 60 ° C. for 2 hours. Next, the washed porous support member with wet gel was immersed in 300 mL of methyl ethyl ketone, and the solvent was replaced at 60 ° C. for 2 hours. This solvent replacement operation was performed twice while exchanging with new methyl ethyl ketone. The porous support member 1 with an airgel composite was obtained by drying the washed and solvent-substituted porous support member with a wet gel at 120 ° C. for 10 hours under normal pressure.

(Example 2)
[Wet gel, airgel composite]
100.0 parts by mass of PL-2L as a silica particle-containing raw material, 100.0 parts by mass of water, 0.10 parts by mass of acetic acid as an acid catalyst, cetyltrimethylammonium bromide as a cationic surfactant (Wako Pure Chemical Industries, Ltd.) Co., Ltd .: hereinafter abbreviated as “CTAB”) is mixed with 20.0 parts by mass of urea and 120.0 parts by mass of urea as a thermohydrolyzable compound, and then 70.0 parts by mass of MTMS and 30 parts of DMDMS as silicon compounds. 0.0 part by mass was added and reacted at 25 ° C. for 2 hours to obtain sol 2. The obtained sol 2 was gelled at 60 ° C. and then aged at 80 ° C. for 24 hours to obtain a wet gel 2. Then, the airgel composite 2 which has the structure represented by the said General formula (4) and (5) was obtained like Example 1 using the obtained wet gel 2. FIG.

[Support member with airgel composite]
In the same manner as in Example 1, using the sol 2, a film-like support member 2 with an airgel composite, a sheet-like support member 2 with an airgel composite, a foil-like support member 2 with an airgel composite, and a porous with an airgel composite A quality support member 2 was obtained.

(Example 3)
[Wet gel, airgel composite]
200.0 parts by mass of PL-5 as a silica particle-containing raw material, 0.10 parts by mass of acetic acid as an acid catalyst, 20.0 parts by mass of CTAB as a cationic surfactant, and 120. urea as a thermohydrolyzable compound. 0 parts by mass was mixed, and 60.0 parts by mass of MTMS and 40.0 parts by mass of DMDMS were added as silicon compounds to this, and reacted at 25 ° C. for 2 hours to obtain sol 3. The obtained sol 3 was gelled at 60 ° C. and then aged at 80 ° C. for 24 hours to obtain a wet gel 3. Then, the airgel composite 3 which has the structure represented by the said General formula (4) and (5) was obtained like Example 1 using the obtained wet gel 3. FIG.

[Support member with airgel composite]
Using the sol 3, as in Example 1, a film-like support member 3 with an airgel composite, a sheet-like support member 3 with an airgel composite, a foil-like support member 3 with an airgel composite, and a porous with an airgel composite A quality support member 3 was obtained.

(Example 4)
[Wet gel, airgel composite]
100.0 parts by mass of PL-2L as a raw material containing silica particles, 100.0 parts by mass of water, 0.10 parts by mass of acetic acid as an acid catalyst, 20.0 parts by mass of CTAB as a cationic surfactant, and hot water addition 120.0 parts by mass of urea is mixed as a decomposable compound, 60.0 parts by mass of MTMS and 20.0 parts by mass of DMDMS as a silicon compound, and 20.0 parts by mass of polysiloxane compound A as a polysiloxane compound. In addition, sol 4 was obtained by reacting at 25 ° C. for 2 hours. The obtained sol 4 was gelled at 60 ° C. and then aged at 80 ° C. for 24 hours to obtain a wet gel 4. Thereafter, an airgel composite 4 having a structure represented by the general formulas (3), (4), and (5) was obtained in the same manner as in Example 1 by using the obtained wet gel 4.

The “polysiloxane compound A” was synthesized as follows. First, in a 1 liter three-necked flask equipped with a stirrer, a thermometer and a Dimroth condenser, 100.0 parts by mass of hydroxy-terminated dimethylpolysiloxane “XC96-723” (product name, manufactured by Momentive), methyl 181.3 parts by mass of trimethoxysilane and 0.50 parts by mass of t-butylamine were mixed and reacted at 30 ° C. for 5 hours. Thereafter, this reaction solution was heated at 140 ° C. for 2 hours under reduced pressure of 1.3 kPa to remove volatile components, thereby obtaining a bifunctional alkoxy-modified polysiloxane compound (polysiloxane compound A) at both ends.

[Support member with airgel composite]
Using the sol 4, as in Example 1, a film-like support member 4 with an airgel composite, a sheet-like support member 4 with an airgel composite, a foil-like support member 4 with an airgel composite, and a porous with an airgel composite A quality support member 4 was obtained.

(Example 5)
[Wet gel, airgel composite]
As a silica particle-containing raw material, 100.0 parts by mass of HL-3L, 100.0 parts by mass of water, 0.10 parts by mass of acetic acid as an acid catalyst, 20.0 parts by mass of CTAB as a cationic surfactant, and thermal hydrolysis 120.0 parts by mass of urea is mixed as a decomposable compound, 60.0 parts by mass of MTMS and 20.0 parts by mass of DMDMS as a silicon compound, and 20.0 parts by mass of polysiloxane compound A as a polysiloxane compound. In addition, sol 5 was obtained by reacting at 25 ° C. for 2 hours. The obtained sol 5 was gelled at 60 ° C. and then aged at 80 ° C. for 24 hours to obtain a wet gel 5. Then, the airgel composite 5 which has the structure represented by the said General formula (3), (4) and (5) was obtained like Example 1 using the obtained wet gel 5. FIG.

[Support member with airgel composite]
Using the sol 5, as in Example 1, a film-like support member 5 with an airgel composite, a sheet-like support member 5 with an airgel composite, a foil-like support member 5 with an airgel composite, and a porous with an airgel composite A quality support member 5 was obtained.

(Comparative Example 1)
[Wet gel, aerogel]
200.0 parts by mass of water, 0.10 parts by mass of acetic acid as an acid catalyst, 20.0 parts by mass of CTAB as a cationic surfactant, and 120.0 parts by mass of urea as a thermohydrolyzable compound were mixed. 100.0 parts by mass of MTMS as a silicon compound was added and reacted at 25 ° C. for 2 hours to obtain Sol 1C. The obtained sol 1C was gelled at 60 ° C. and then aged at 80 ° C. for 24 hours to obtain a wet gel 1C. Thereafter, an airgel 1C was obtained in the same manner as in Example 1 by using the obtained wet gel 1C.

[Supporting member with airgel]
Using the sol 1C, a film-like support member 1C with an airgel, a sheet-like support member 1C with an airgel, a foil-like support member 1C with an airgel, and a porous support member 1C with an airgel were obtained in the same manner as in Example 1.

(Comparative Example 2)
[Wet gel, aerogel]
200.0 parts by mass of water, 0.10 parts by mass of acetic acid as an acid catalyst, 20.0 parts by mass of CTAB as a cationic surfactant, and 120.0 parts by mass of urea as a thermohydrolyzable compound were mixed. As a silicon compound, 80.0 parts by mass of MTMS and 20.0 parts by mass of DMDMS were added and reacted at 25 ° C. for 2 hours to obtain sol 2C. The obtained sol 2C was gelled at 60 ° C. and then aged at 80 ° C. for 24 hours to obtain a wet gel 2C. Thereafter, an airgel 2C was obtained in the same manner as in Example 1 using the obtained wet gel 2C.

[Supporting member with airgel]
Using the sol 2C, a film-like support member 2C with an airgel, a sheet-like support member 2C with an airgel, a foil-like support member 2C with an airgel, and a porous support member 2C with an airgel were obtained in the same manner as in Example 1.

(Comparative Example 3)
[Wet gel, aerogel]
200.0 parts by mass of water, 0.10 parts by mass of acetic acid as an acid catalyst, 20.0 parts by mass of CTAB as a cationic surfactant, and 120.0 parts by mass of urea as a thermohydrolyzable compound were mixed. As a silicon compound, 70.0 parts by mass of MTMS and 30.0 parts by mass of DMDMS were added and reacted at 25 ° C. for 2 hours to obtain sol 3C. The obtained sol 3C was gelled at 60 ° C. and then aged at 80 ° C. for 24 hours to obtain a wet gel 3C. Thereafter, an airgel 3C was obtained in the same manner as in Example 1 by using the obtained wet gel 3C.

[Supporting member with airgel]
Using the sol 3C, a film-like support member 3C with an airgel, a sheet-like support member 3C with an airgel, a foil-like support member 3C with an airgel, and a porous support member 3C with an airgel were obtained in the same manner as in Example 1.

Table 1 summarizes the modes of the silica particle-containing raw materials in each example. Table 2 summarizes the drying method, the types and addition amounts of Si raw materials (silicon compounds and polysiloxane compounds), and the addition amounts of silica particle-containing raw materials in each Example and Comparative Example.

[Various evaluations]
The wet gel, airgel composite and support member with airgel composite obtained in each example, and the wet gel, airgel and support member with airgel obtained in each comparative example were measured or evaluated according to the following conditions. Summary of gelation time in wet gel formation process, airgel composite and airgel state in atmospheric pressure drying of methanol-substituted gel, and evaluation results of thermal conductivity, compressive elastic modulus, density and porosity of airgel composite and airgel Table 3 summarizes the evaluation results of the 180 ° bending test of the support member with the airgel composite and the support member with the airgel.

(1) Measurement of gelation time 30 mL of the sol obtained in each Example and Comparative Example was transferred to a 100 mL PP sealed container to obtain a measurement sample. Next, using a constant temperature dryer “DVS402” (manufactured by Yamato Kagaku Co., Ltd., product name) set to 60 ° C., the time from when the measurement sample was introduced to gelation was measured.

(2) State of airgel complex and airgel in atmospheric pressure drying of methanol-substituted gel 30.0 parts by mass of wet gel obtained in each Example and Comparative Example was immersed in 150.0 parts by mass of methanol at 60 ° C. Washing was performed for 12 hours. This washing operation was performed 3 times while exchanging with fresh methanol. Next, the washed wet gel was processed into a size of 100 × 100 × 100 mm ³ using a blade having a blade angle of about 20 to 25 degrees to obtain a sample before drying. The obtained pre-drying sample was dried at 60 ° C. for 2 hours and at 100 ° C. for 3 hours using a constant temperature chamber “SPH (H) -202” (product name, manufactured by ESPEC Corporation) with a safety door, and then further 150 A sample was obtained after drying by drying at 2 ° C. for 2 hours (particularly the solvent evaporation rate was not controlled). Here, the volume shrinkage ratio SV before and after drying of the sample was obtained from the following equation. When the volume shrinkage ratio SV was 5% or less, it was evaluated as “no contraction”, and when it was 5% or more, it was evaluated as “shrinkage”.
SV = (V ₀ −V ₁ ) / V ₀ × 100
In the formula, V ₀ represents the volume of the sample before drying, and V ₁ represents the volume of the sample after drying.

(3) Measurement of thermal conductivity Using a blade having a blade angle of about 20 to 25 degrees, the airgel composite and the airgel were processed into a size of 150 × 150 × 100 mm ³ to obtain a measurement sample. Next, in order to ensure parallelism of the surface, shaping was performed with sandpaper of # 1500 or more as necessary. The obtained measurement sample was dried at 100 ° C. for 30 minutes under atmospheric pressure using a constant temperature dryer “DVS402” (manufactured by Yamato Scientific Co., Ltd., product name) before measuring the thermal conductivity. The measurement sample was then transferred into a desiccator and cooled to 25 ° C. Thereby, the measurement sample for thermal conductivity measurement was obtained.

The thermal conductivity was measured using a steady-state thermal conductivity measuring device “HFM436 Lambda” (manufactured by NETZSCH, product name). The measurement conditions were an average temperature of 25 ° C. under atmospheric pressure. The measurement sample obtained as described above was sandwiched between the upper and lower heaters with a load of 0.3 MPa, the temperature difference ΔT was set to 20 ° C., and the guard sample was adjusted so as to obtain a one-dimensional heat flow. Upper surface temperature, lower surface temperature, etc. were measured. And thermal resistance _RS of the measurement sample was calculated | required from following Formula.
R _S = N ((T _U −T _L ) / Q) −R _O
Wherein, T _U represents a measurement sample top surface temperature, T _L represents the measurement sample lower surface temperature, R _O represents the thermal contact resistance of the upper and lower interfaces, Q is shows the heat flux meter output. Note that N is a proportionality coefficient, and is obtained in advance using a calibration sample.

From the obtained thermal resistance _RS , the thermal conductivity λ of the measurement sample was obtained from the following equation.
λ = d / R _S
In formula, d shows the thickness of a measurement sample.

(4) Measurement of compression elastic modulus Using a blade having a blade angle of about 20 to 25 degrees, the airgel composite and the airgel were processed into 7.0 mm square cubes (diced) to obtain measurement samples. Next, in order to ensure parallelism of the surfaces, the measurement sample was shaped with sandpaper of # 1500 or more as necessary. The obtained measurement sample was dried at 100 ° C. for 30 minutes under atmospheric pressure using a constant temperature dryer “DVS402” (manufactured by Yamato Scientific Co., Ltd., product name) before measurement. The measurement sample was then transferred into a desiccator and cooled to 25 ° C. Thereby, the measurement sample for compression elastic modulus measurement was obtained.

As a measuring apparatus, a small tabletop testing machine “EZTest” (manufactured by Shimadzu Corporation, product name) was used. In addition, 500N was used as a load cell. Further, an upper platen (φ20 mm) and a lower platen (φ118 mm) made of stainless steel were used as compression measurement jigs. A measurement sample was set between an upper platen and a lower platen arranged in parallel, and compression was performed at a speed of 1 mm / min. The measurement temperature was 25 ° C., and the measurement was terminated when a load exceeding 500 N was applied or when the measurement sample was destroyed. Here, the strain ε was obtained from the following equation.
ε = Δd / d1
In the formula, Δd represents the displacement (mm) of the thickness of the measurement sample due to the load, and d1 represents the thickness (mm) of the measurement sample before the load is applied.
The compressive stress σ (MPa) was obtained from the following equation.
σ = F / A
In the formula, F represents the compressive force (N), and A represents the cross-sectional area (mm ² ) of the measurement sample before applying a load.

The compressive elastic modulus E (MPa) was obtained from the following equation in the compression force range of 0.1 to 0.2N.
E = (σ ₂ −σ ₁ ) / (ε ₂ −ε ₁ )
In the formula, σ ₁ indicates a compressive stress (MPa) measured at a compressive force of 0.1 N, σ ₂ indicates a compressive stress (MPa) measured at a compressive force of 0.2 N, and ε ₁ indicates a compressive stress. The compressive strain measured at σ ₁ is shown, and ε ₂ shows the compressive strain measured at the compressive stress σ ₂ .

(5) Measurement of density and porosity The density and porosity of pores (through holes) continuous in a three-dimensional network for the airgel composite and the airgel were measured by a mercury intrusion method according to DIN 66133. The measurement temperature was room temperature (25 ° C.), and Autopore IV9520 (manufactured by Shimadzu Corporation, product name) was used as the measurement apparatus.

(6) Flexural resistance test The support member with an airgel composite and the support member with an airgel obtained in each of the examples and comparative examples were processed to a width of 50 mm, and the mandrel on the airgel composite layer side according to JIS K5600-1. A test was conducted. A mandrel tester manufactured by Toyo Seiki Seisakusho was used. The presence or absence of cracks and peeling on the airgel composite and the airgel layer when bent 180 ° at a mandrel radius of 1 mm was visually evaluated. And the thing which a crack and peeling did not generate | occur | produce was evaluated as "non-destructive", and the thing which a crack or peeling generate | occur | produced was evaluated as "destructive".

From Table 3, the airgel composites of the examples had a short gelation time in the wet gel production process and excellent reactivity, and had good shrinkage resistance in atmospheric drying using a methanol-substituted gel. In addition, in this evaluation, it was shown that good shrinkage resistance was shown in any of the examples, that is, a good-quality airgel composite could be obtained without performing the solvent replacement step. .

Also, it can be read that the airgel composites of the examples have small thermal conductivity and compression modulus, and are excellent in both high heat insulation and high flexibility. Moreover, the support member with an airgel composite of the example had good bending resistance.

On the other hand, in Comparative Examples 1 to 3, the gelation time in the wet gel production process was long, and in normal pressure drying using a methanol-substituted gel, the gel contracted and cracks occurred on the surface. Moreover, either thermal conductivity or flexibility was inferior. Furthermore, since the support member with an airgel is brittle with respect to bending, it has been easily broken.

(7) SEM observation The surface of the airgel composite in the foil-like support member with an airgel composite obtained in Example 4 was observed by SEM. FIG. 3 shows the surface of the airgel composite in the foil-like support member with the airgel composite obtained in Example 4, (a) 10,000 times, (b) 50,000 times, (c) 200,000 times and (d ) SEM images observed at 350,000 times.

As shown in FIG. 3, it was observed that the airgel composite obtained in Example 4 had a three-dimensional network skeleton (three-dimensionally fine porous structure). The observed particle size was mainly about 20 nm derived from silica particles. Spherical airgel components (aerogel particles) with a particle size smaller than that of the silica particles can also be confirmed, but mainly the airgel components do not take a spherical form and cover the silica particles or function as a binder between the silica particles. Observed to be. Thus, since a part of airgel component functions as a binder between silica particles, it is guessed that the intensity | strength of an airgel composite can be improved.

1 ... airgel particles, 2 ... silica particles, 3 ... pores, 10 ... airgel composite, L ... circumscribed rectangle.

Claims

An airgel composite containing an airgel component and silica particles derived from alkoxysilane.
The airgel composite according to claim 1, comprising a three-dimensional network skeleton formed from the airgel component and the silica particles, and pores.
An airgel composite containing silica particles derived from alkoxysilane as a component constituting a three-dimensional network skeleton.
It is selected from the group consisting of alkoxysilane-derived silica particles, a silicon compound having a hydrolyzable functional group or a condensable functional group, and a hydrolysis product of the silicon compound having the hydrolyzable functional group. An airgel composite which is a dried product of a wet gel which is a condensate of a sol containing at least one kind.
Selected from the group consisting of silica particles derived from the alkoxysilane, a silicon compound having a hydrolyzable functional group or a condensable functional group, and a hydrolysis product of the silicon compound having the hydrolyzable functional group. The airgel composite according to any one of claims 1 to 3, which is a dried product of a wet gel that is a condensate of a sol containing at least one of the above.
The airgel composite according to claim 4 or 5, wherein the silicon compound includes a polysiloxane compound having a hydrolyzable functional group or a condensable functional group.
The airgel composite according to any one of claims 1 to 6, wherein the silica particles have an average primary particle diameter of 1 to 500 nm.
The airgel composite according to any one of claims 1 to 7, wherein the silica particles are colloidal silica particles.
A support member with an airgel composite comprising: the airgel composite according to any one of claims 1 to 8; and a support member that supports the airgel composite.
A heat insulating material comprising the airgel composite according to any one of claims 1 to 8.