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  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/80—Processes for incorporating ingredients
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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  • C09D123/00—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers
  • C09D123/02—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
  • C09D123/04—Homopolymers or copolymers of ethene
  • C09D123/08—Copolymers of ethene
  • C09D123/0846—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms
  • C09D123/0892—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms containing monomers with other atoms than carbon, hydrogen or oxygen atoms
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  • C09D183/00—Coating compositions based on macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon, with or without sulfur, nitrogen, oxygen, or carbon only; Coating compositions based on derivatives of such polymers
  • C09D183/10—Block or graft copolymers containing polysiloxane sequences
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  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
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  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/02—Emulsion paints including aerosols
  • C09D5/022—Emulsions, e.g. oil in water
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  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/02—Emulsion paints including aerosols
  • C09D5/024—Emulsion paints including aerosols characterised by the additives
  • C09D5/028—Pigments; Filters
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  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/65—Additives macromolecular
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/66—Additives characterised by particle size
  • C09D7/69—Particle size larger than 1000 nm
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  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/70—Additives characterised by shape, e.g. fibres, flakes or microspheres
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/42—Block-or graft-polymers containing polysiloxane sequences
  • C08G77/442—Block-or graft-polymers containing polysiloxane sequences containing vinyl polymer sequences
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/002—Physical properties
  • C08K2201/005—Additives being defined by their particle size in general
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/22—Expanded, porous or hollow particles
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K7/00—Use of ingredients characterised by shape
  • C08K7/22—Expanded, porous or hollow particles
  • C08K7/24—Expanded, porous or hollow particles inorganic
  • C08K7/26—Silicon- containing compounds
• • C—CHEMISTRY; METALLURGY
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  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D101/00—Coating compositions based on cellulose, modified cellulose, or cellulose derivatives
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D123/00—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers
  • C09D123/02—Coating compositions based on homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
  • C09D123/04—Homopolymers or copolymers of ethene
  • C09D123/08—Copolymers of ethene
  • C09D123/0846—Copolymers of ethene with unsaturated hydrocarbons containing other atoms than carbon or hydrogen atoms
  • C09D123/0853—Vinylacetate
• • C—CHEMISTRY; METALLURGY
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  • C09D131/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an acyloxy radical of a saturated carboxylic acid, of carbonic acid, or of a haloformic acid; Coating compositions based on derivatives of such polymers
  • C09D131/02—Homopolymers or copolymers of esters of monocarboxylic acids
  • C09D131/04—Homopolymers or copolymers of vinyl acetate
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D201/00—Coating compositions based on unspecified macromolecular compounds
  • C09D201/02—Coating compositions based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
  • C09D7/62—Additives non-macromolecular inorganic modified by treatment with other compounds
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L59/00—Thermal insulation in general
  • F16L59/06—Arrangements using an air layer or vacuum

Definitions

• the present invention relates to a coating liquid manufacturing method and a heat insulating material manufacturing method.
• Airgel is known as a material with excellent heat insulation. Moreover, a method of processing airgel into particles and using them as constituent materials of heat insulating materials has been proposed (for example, Patent Documents 1 and 2). Patent Literature 1 proposes using particulate airgel as a filler between resin plates or the like that constitute a heat insulating window. In Patent Document 2, after preparing an aqueous dispersion containing airgel particles and organic fibers, the intermediate product obtained by evaporating water is further press-molded to produce a heat insulating material (molded body). It is shown.
• a composite material in which airgel particles are dispersed in a resin component is expected to have excellent heat resistance.
• the resin component permeates into the pores of the airgel particles, the pore structure is lost, and the heat insulating properties are reduced. There was a problem that could easily arise.
• the present invention is to provide a method for producing a heat insulating material that suppresses the penetration of the resin component into the pores of the airgel particles and can obtain a heat insulating material having high heat insulating properties and high film-forming properties.
• Another object of the present invention is to provide a coating liquid for forming the heat insulating material and a method for producing the coating liquid.
• One aspect of the present invention includes a preparation step of preparing an emulsion containing a polymer emulsifier, a binder resin and a liquid medium, and airgel particles, and mixing the emulsion and the airgel particles prepared in the preparation step. and a mixing step of aggregating at least part of the airgel particles to obtain a coating liquid containing the airgel particle aggregates, the polymeric emulsifier, the binder resin and the liquid medium. It relates to a manufacturing method.
• the coating liquid obtained by the above manufacturing method the contact interface between the airgel particles and the resin component is reduced due to aggregation of the airgel particles, and the permeation of the resin component into the pores of the airgel particles is suppressed.
• the coating liquid obtained by the above production method is not a mixture of airgel particle aggregates prepared in advance, but is agglomerated when the airgel particles are mixed with other components, so the airgel particles and their aggregates is uniformly dispersed, and it is possible to suppress uneven distribution of the airgel particles, cracking, etc. of the coating film.
• the binder resin emulsified with the macromolecular emulsifier is mixed in advance, the permeation of the resin component into the pores of the airgel particles is further suppressed. Therefore, according to the coating liquid obtained by the above manufacturing method, a heat insulating material having high heat insulating properties and high film formability can be obtained.
• the binder resin in the emulsion is covered with the polymer emulsifier due to the use of the polymer emulsifier, so that the fine particles of the binder resin and the aggregates of the airgel particles are difficult to contact, and the airgel particles It is difficult for the binder resin to enter the gaps in the aggregates, and the aggregates of the airgel particles are difficult to collapse.
• the coating film obtained by the above production method is easy to maintain without collapsing the airgel particle aggregates even if a certain amount of pressure is applied during coating.
• a high-pressure coating method such as airless spraying is preferably used. be able to.
• the average diameter of the aggregates may be 2 to 40 times the average diameter of the airgel particles prepared in the preparation step.
• the area occupied by the aggregates having a diameter of 20 ⁇ m or more out of the area occupied by the airgel particles and the aggregates in the observation field is 50%. or more.
• the total content of the airgel particles and the aggregates in the coating liquid may be 70% by volume or more based on the total solid content.
• the mixing step may be a step of further mixing a water-soluble polymer having a hydrophobic group, and the coating liquid may further contain the water-soluble polymer. This further improves the dispersibility of the airgel particles, making it easier to obtain a coating liquid in which the airgel particles and aggregates thereof are uniformly dispersed even when the filling rate of the airgel particles is increased.
• Another aspect of the present invention comprises a coating step of applying the coating liquid produced by the above production method onto a support to obtain a coating film, and removing at least part of the liquid medium from the coating film. and a removal step to obtain the insulation.
• a coating step of applying the coating liquid produced by the above production method onto a support to obtain a coating film, and removing at least part of the liquid medium from the coating film. and a removal step to obtain the insulation According to such a manufacturing method, the penetration of the resin component into the pores of the airgel particles is suppressed, and a heat insulating material having high heat insulating properties and high film formability can be easily obtained.
• the insulating material may have a pore volume of 0.15 cm 3 /g or more.
• the coating step may be a step of applying the coating liquid by a coating method in which the pressure applied to the coating liquid exceeds 1.5 MPa.
• Yet another aspect of the present invention is a coating liquid containing agglomerates of airgel particles, a polymeric emulsifier, a binder resin and a liquid medium.
• the present invention relates to a coating liquid, wherein 50% or more of the area occupied by the airgel particles and the aggregates in the observation field is occupied by the aggregates having a diameter of 20 ⁇ m or more.
• the present invention it is possible to obtain a heat insulating material having high heat insulating properties and high film-forming properties by suppressing the penetration of the resin component into the pores of the airgel particles.
• a method for producing a heat insulating material is provided. .
• the coating liquid for forming the said heat insulating material, and its manufacturing method are provided.
• the coating liquid manufacturing method of the present embodiment includes a preparation step of preparing an emulsion containing a polymer emulsifier, a binder resin and a liquid medium, and airgel particles, and mixing the emulsion and airgel particles prepared in the preparation step. and a mixing step of aggregating at least part of the airgel particles to obtain a coating liquid containing the aggregates of the airgel particles, the polymeric emulsifier, the binder resin and the liquid medium.
• the contact interface between the airgel particles and the resin component is reduced due to aggregation of the airgel particles, and the permeation of the resin component into the pores of the airgel particles is suppressed.
• it is conceivable to prepare aggregates of airgel particles in advance but in this case, it is difficult to disperse the aggregates in the coating liquid. There is also a possibility that the aggregate will collapse.
• the airgel particles and their aggregates are uniformly dispersed, and uneven distribution of the airgel particles, cracking, etc. of the coating film are suppressed.
• the binder resin emulsified in advance with the polymer emulsifier is mixed, the permeation of the resin component into the pores of the airgel particles is further suppressed. Therefore, according to the manufacturing method of the present embodiment, it is possible to obtain a coating liquid capable of forming a heat insulating material having high heat insulating properties and high film formability.
• the binder resin in the emulsion is covered with the polymer emulsifier due to the use of the polymer emulsifier, so the fine particles of the binder resin and the aggregates of the airgel particles are difficult to contact. , the binder resin is less likely to enter the gaps in the aggregates of the airgel particles, and the aggregates of the airgel particles are less likely to collapse. Therefore, the coating film obtained by the production method of the present embodiment is easy to maintain without collapsing the airgel particle aggregates even if a certain amount of pressure is applied during coating. It can be used preferably.
• the method for producing a heat insulating material of the present embodiment includes a coating step of applying the coating liquid produced by the above method on a support to obtain a coating film, and removing at least a part of the liquid medium from the coating film to heat insulation. and a removal step to obtain material.
• the method for manufacturing a heat insulating material of the present embodiment may further include a coating liquid manufacturing step of obtaining a coating liquid by the above method.
• the penetration of the resin component into the pores of the airgel particles is suppressed, and it is possible to easily obtain a heat insulating material with high heat insulating properties and high film-forming properties.
• a dry gel obtained by supercritical drying of a wet gel is called aerogel
• a dry gel obtained by drying under atmospheric pressure is called xerogel
• a dry gel obtained by freeze-drying is called cryogel.
• the resulting low-density dried gel is referred to as an "aerogel” regardless of these drying techniques for wet gels. That is, in the present embodiment, “aerogel” is aerogel in a broad sense, "Gel comprised of a microporous solid in which the dispersed phase is a gas (a gel composed of a microporous solid in which the dispersed phase is a gas). ” means.
• the inside of an airgel has a network-like fine structure, and has a cluster structure in which particulate airgel components of about 2 to 20 nm are bonded. Between the frameworks formed by these clusters are pores less than 100 nm. As a result, the airgel has a three-dimensional fine porous structure.
• the airgel according to the present embodiment is, for example, silica airgel containing silica as a main component.
• silica airgel include so-called organic-inorganic hybridized silica airgel into which an organic group (such as a methyl group) or an organic chain is introduced.
• Examples of the airgel according to this embodiment include the following aspects. By adopting these aspects, it becomes easy to obtain an airgel excellent in heat insulation, flame retardancy, heat resistance and flexibility. By adopting each aspect, it is possible to obtain an airgel having thermal insulation, flame retardancy, heat resistance and flexibility according to each aspect.
• the airgel according to this embodiment can have a structure represented by the following general formula (1).
• the airgel according to this embodiment can have a structure represented by the following general formula (1a) as a structure containing the structure represented by formula (1).
• R 1 and R 2 each independently represent an alkyl group or an aryl group
• R 3 and R 4 each independently represent an alkylene group.
• the aryl group includes a phenyl group, a substituted phenyl group, and the like.
• Substituents for the substituted phenyl group include an alkyl group, a vinyl group, a mercapto group, an amino group, a nitro group, a cyano group and the like.
• p represents an integer from 1 to 50;
• two or more R 1 's may be the same or different, and two or more R 2 's may be the same or different.
• two R 3 may be the same or different, and similarly, two R 4 may be the same or different.
• R 1 and R 2 each independently include an alkyl group having 1 to 6 carbon atoms, a phenyl group, and the like. and the like.
• R 3 and R 4 each independently include an alkylene group having 1 to 6 carbon atoms, and examples of the alkylene group include an ethylene group and a propylene group. be done.
• p can be 2-30, and may be 5-20.
• the airgel according to the present embodiment can have a ladder-type structure comprising a strut portion and a bridging portion, and the bridging portion can have a structure represented by the following general formula (2).
• Heat resistance and mechanical strength can be improved by introducing such a ladder structure as an airgel component into the skeleton of the airgel.
• the “ladder structure” refers to a structure having two struts and bridges that connect the struts (having a so-called “ladder” form) is.
• the skeleton of the airgel may have a ladder-type structure, or the airgel may partially have a ladder-type structure.
• R 5 and R 6 each independently represent an alkyl group or an aryl group, and b represents an integer of 1-50.
• the aryl group includes a phenyl group, a substituted phenyl group, and the like.
• Substituents for the substituted phenyl group include alkyl groups, vinyl groups, mercapto groups, amino groups, nitro groups, cyano groups and the like.
• b is an integer of 2 or more
• two or more R 5 may be the same or different, and two or more R 6 may also be the same. may also be different.
• the airgel skeleton As an airgel component, for example, it has a structure derived from a conventional ladder-type silsesquioxane (i.e., has a structure represented by the following general formula (X)) It becomes an airgel having flexibility superior to that of an airgel.
• Silsesquioxane is a polysiloxane having a compositional formula: (RSiO 1.5 ) n and can have various skeleton structures such as a cage type, ladder type and random type.
• the structure of the bridging portion is -O-, but the airgel according to the present embodiment Then, the structure of the bridging portion is the structure (polysiloxane structure) represented by the general formula (2).
• the airgel of this aspect may have a structure derived from silsesquioxane in addition to the structure represented by general formula (2).
• R represents a hydroxy group, an alkyl group or an aryl group.
• the structure and chain length of the struts, and the spacing of the structure that serves as the bridging portion are not particularly limited. 3) may have a ladder-type structure.
• R 5 , R 6 , R 7 and R 8 each independently represent an alkyl group or an aryl group, a and c each independently represent an integer of 1 to 3000, b is 1 to 50 Indicates an integer.
• the aryl group includes a phenyl group, a substituted phenyl group, and the like. Substituents for the substituted phenyl group include alkyl groups, vinyl groups, mercapto groups, amino groups, nitro groups, cyano groups and the like.
• b is an integer of 2 or more
• two or more R 5 may be the same or different
• two or more R 6 may also be the same.
• formula (3) when a is an integer of 2 or more, two or more R 7 may be the same or different, and similarly when c is an integer of 2 or more, two or more each R 8 may be the same or different.
• R 5 , R 6 , R 7 and R 8 each independently include an alkyl group having 1 to 6 carbon atoms, a phenyl group and the like, and the alkyl group includes a methyl group and the like.
• a and c can be independently 6 to 2,000, but may be 10 to 1,000.
• b can be 2 to 30, but may be 5 to 20.
• the airgel according to the present embodiment is at least selected from the group consisting of a silicon compound having a hydrolyzable functional group or a condensable functional group, and a hydrolysis product of a silicon compound having a hydrolyzable functional group It may be a dried wet gel that is a condensate of a sol containing one type of sol (obtained by drying a wet gel produced from a sol: a dried wet gel derived from a sol). The airgel described so far may also be obtained by drying a wet gel produced from a sol containing a silicon compound or the like.
• a polysiloxane compound can be used as the silicon compound having a hydrolyzable functional group or a condensable functional group. That is, the sol is at least selected from the group consisting of a polysiloxane compound having a hydrolyzable functional group or a condensable functional group, and a hydrolysis product of a polysiloxane compound having a hydrolyzable functional group. It can contain one type of compound (hereinafter sometimes referred to as "polysiloxane compound group").
• the functional groups in the polysiloxane compound are not particularly limited, but may be groups that react with the same functional groups or groups that react with other functional groups.
• Hydrolyzable functional groups include alkoxy groups.
• Examples of condensable functional groups include hydroxyl groups, silanol groups, carboxyl groups, and phenolic hydroxyl groups.
• a 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 has a reactive group different from the hydrolyzable functional group and the condensable functional group (hydrolyzable functional group and condensable functional group).
• Reactive groups include epoxy group, mercapto group, glycidoxy group, vinyl group, acryloyl group, methacryloyl group, amino group and the like.
• the epoxy group may be contained in an epoxy group-containing group such as a glycidoxy group.
• Polysiloxane compounds having these functional groups and reactive groups may be used alone or in combination of two or more.
• groups that improve the flexibility of the airgel include alkoxy groups, silanol groups, hydroxyalkyl groups, etc.
• the alkoxy groups and hydroxyalkyl groups are The compatibility of the sol can be further improved.
• the number of carbon atoms of the alkoxy group and the hydroxyalkyl group can be 1 to 6, but the flexibility of the airgel is further improved. From the point of view, it may be 2 to 5, or 2 to 4.
• Polysiloxane compounds having a hydroxyalkyl group in the molecule include those having a structure represented by the following general formula (A).
• A a polysiloxane compound having a structure represented by the following general formula (A)
• the structures represented by general formulas (1) and (1a) can be introduced into the skeleton of the airgel.
• R 1a represents a hydroxyalkyl group
• R 2a represents an alkylene group
• R 3a and R 4a each independently represent an alkyl group or an aryl group
• n represents an integer of 1-50.
• the aryl group includes a phenyl group, a substituted phenyl group, and the like.
• Substituents for the substituted phenyl group include alkyl groups, vinyl groups, mercapto groups, amino groups, nitro groups, cyano groups and the like.
• two R 1a may be the same or different
• two R 2a may be the same or different.
• two or more R 3a may be the same or different
• two or more R 4a may be the same or different.
• R 1a in formula (A) includes a hydroxyalkyl group having 1 to 6 carbon atoms, and examples of the hydroxyalkyl group include a hydroxyethyl group and a hydroxypropyl group.
• R 2a in formula (A) includes an alkylene group having 1 to 6 carbon atoms, and examples of the alkylene group include an ethylene group and a propylene group.
• R 3a and R 4a each independently include an alkyl group having 1 to 6 carbon atoms, a phenyl group, and the like, and the alkyl group includes a methyl group and the like.
• n can range from 2 to 30, but may range from 5 to 20.
• polysiloxane compound having the structure represented by the general formula (A) commercially available products can be used, and compounds such as X-22-160AS, KF-6001, KF-6002, KF-6003 (all , Shin-Etsu Chemical Co., Ltd.), compounds such as XF42-B0970, Fluid OFOH 702-4% (all of which are manufactured by Momentive).
• Polysiloxane compounds having an alkoxy group in the molecule include those having a structure represented by the following general formula (B).
• a ladder-type structure having a bridging portion represented by the general formula (2) or (3) is introduced into the airgel skeleton. can do.
• R 1b represents an alkyl group, an alkoxy group or an aryl group
• R 2b and R 3b each independently represent an alkoxy group
• R 4b and R 5b each independently represent an alkyl group or an aryl group.
• m represents an integer from 1 to 50.
• the aryl group includes a phenyl group, a substituted phenyl group, and the like.
• Substituents for the substituted phenyl group include alkyl groups, vinyl groups, mercapto groups, amino groups, nitro groups, cyano groups and the like.
• two R 1b may be the same or different, two R 2b may be the same or different, and similarly two R 3b may be the same or different.
• 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 also be different.
• R 1b includes an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, and the like, and the alkyl group or alkoxy group is a methyl group. , methoxy group, ethoxy group and the like.
• R 2b and R 3b each independently include an alkoxy group having 1 to 6 carbon atoms, and the alkoxy group includes a methoxy group, an ethoxy group, and the like.
• R 4b and R 5b each independently include an alkyl group having 1 to 6 carbon atoms, a phenyl group, and the like, and the alkyl group includes a methyl group and the like.
• m can range from 2 to 30, but may range from 3 to 35, or from 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 JP-A-2000-26609 and JP-A-2012-233110. .
• XR31-B1410 manufactured by Momentive
• XR31-B1410 can also be used as the polysiloxane compound.
• the polysiloxane compound having an alkoxy group may exist as a hydrolysis product in the sol, and the polysiloxane compound having an alkoxy group and its hydrolysis product are mixed. may be Moreover, in the polysiloxane compound having an alkoxy group, all the alkoxy groups in the molecule may be hydrolyzed or partially hydrolyzed.
• polysiloxane compounds having a hydrolyzable functional group or a condensable functional group, and the hydrolysis products of the polysiloxane compounds having a hydrolyzable functional group may be used alone or in combination of two or more. may be used.
• silicon compounds other than the polysiloxane compounds described above can be used as the silicon compound having a hydrolyzable functional group or a condensable functional group. That is, the sol containing the silicon compound is composed of a silicon compound having a hydrolyzable functional group or a condensable functional group (excluding a polysiloxane compound), and the silicon compound having a hydrolyzable functional group. At least one selected from the group consisting of hydrolysis products (hereinafter sometimes referred to as "silicon compound group"), in addition to the above-mentioned polysiloxane compound group, or instead of the above-mentioned polysiloxane compound group. be able to.
• the number of silicon molecules in the silicon compound can be one or two.
• Examples of the silicon compound having a hydrolyzable functional group in the molecule include, but are not limited to, alkyl silicon alkoxides. From the viewpoint of improving water resistance, the alkyl silicon alkoxide can have 3 or less hydrolyzable functional groups. Examples of such alkyl silicon alkoxides include monoalkyltrialkoxysilanes, monoalkyldialkoxysilanes, dialkyldialkoxysilanes, monoalkylmonoalkoxysilanes, dialkylmonoalkoxysilanes, and trialkylmonoalkoxysilanes.
• Examples include methyltrimethoxysilane, methyldimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, ethyltrimethoxysilane, hexyltrimethoxysilane and the like.
• examples of the hydrolyzable functional group include alkoxy groups such as a methoxy group and an ethoxy group.
• silicon compound having a condensable functional group examples include, but are not limited to, silanetetraol, methylsilanetriol, dimethylsilanediol, phenylsilanetriol, phenylmethylsilanediol, diphenylsilanediol, n-propylsilanetriol, and hexylsilane. triol, octylsilanetriol, decylsilanetriol, trifluoropropylsilanetriol and the like.
• a silicon compound having a hydrolyzable functional group or a condensable functional group has the above-mentioned reactive groups (hydrolyzable functional group and condensable functional group) different from the hydrolyzable functional group and condensable functional group. It may further have a functional group that does not correspond to a group).
• Silicon compounds having 3 or less hydrolyzable functional groups and 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 and the like can also be used.
• silicon compounds having a condensable functional group and a reactive group vinylsilanetriol, 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, ethyltrimethoxysilane, vinyltrimethoxysilane, etc. which are silicon compounds having 3 or less hydrolyzable functional groups at the molecular terminals, can also be used.
• a silicon compound having a hydrolyzable functional group or a condensable functional group (excluding polysiloxane compounds), and a hydrolysis product of the silicon compound having a hydrolyzable functional group may be used alone or in combination of two types. A mixture of the above may be used.
• the structures represented by the following general formulas (4) to (6) can be introduced into the skeleton of the airgel.
• the airgel according to this embodiment can have one of these structures, or two or more of them.
• R9 represents an alkyl group.
• the alkyl group includes an alkyl group having 1 to 6 carbon atoms and the like, and the alkyl group includes a methyl group and the like.
• R 10 and R 11 each independently represent an alkyl group.
• the alkyl group includes an alkyl group having 1 to 6 carbon atoms and the like, and the alkyl group includes a methyl group and the like.
• R 12 represents an alkylene group.
• the alkylene group includes an alkylene group having 1 to 10 carbon atoms and the like, and the alkylene group includes an ethylene group, a hexylene group and the like.
• the airgel according to the present embodiment may further contain silica particles in addition to the airgel component from the viewpoint of further toughening and the viewpoint of achieving even better heat insulation and flexibility.
• An airgel containing an airgel component and silica particles can also be referred to as an airgel composite.
• the airgel composite has a cluster structure, which is a characteristic of airgel, even though the airgel component and silica particles are composited, and is considered to have a three-dimensionally fine porous structure. .
• the airgel containing the airgel component and silica particles is composed of the silicon compound having a hydrolyzable functional group or condensable functional group and the hydrolysis product of the silicon compound having a hydrolyzable functional group. It can be said to be a dried wet gel that is a condensate of a sol containing at least one selected from the group and silica particles. Therefore, the descriptions regarding the first to third aspects can be appropriately applied mutatis mutandis to the airgel according to the present embodiment.
• the silica particles can be used without any particular limitation, and include amorphous silica particles and the like.
• Amorphous silica particles include fused silica particles, fumed silica particles, colloidal silica particles, and the like.
• colloidal silica particles have high monodispersity and easily suppress aggregation in the sol.
• the silica particles may be silica particles having a hollow structure, a porous structure, or the like.
• the shape of the silica particles is not particularly limited, and may be spherical, cocoon-shaped, association-shaped, or the like. Among these, by using spherical particles as the silica particles, aggregation in the sol can be easily suppressed.
• the average primary particle size of the silica particles may be 1 nm or more, and may be 5 nm or more, from the viewpoint of easily imparting appropriate strength and flexibility to the airgel and easily obtaining an airgel having excellent shrinkage resistance during drying. may be 20 nm or more.
• the average primary particle size of the silica particles may be 500 nm or less, 300 nm or less, or 100 nm from the viewpoint of easily suppressing the solid heat conduction of the silica particles and easily obtaining an airgel having excellent heat insulation properties. It may be below. From these viewpoints, the average primary particle size of silica particles may be 1 to 500 nm, 5 to 300 nm, or 20 to 100 nm.
• the average particle size of the airgel component and the average primary particle size of the silica particles can be obtained by directly observing the airgel using a scanning electron microscope (hereinafter abbreviated as "SEM").
• the “diameter” as used herein means the diameter when the cross section of the particles exposed in the cross section of the airgel is regarded as a circle.
• the diameter when the cross section is regarded as a circle is the diameter of a perfect circle when the area of the cross section is replaced by a perfect circle having the same area.
• the diameters of circles of 100 particles are obtained and the average is taken.
• the average particle size of silica particles can also be measured from raw materials.
• the biaxial average primary particle size is calculated as follows from the result of observing 20 arbitrary particles by SEM. That is, taking colloidal silica particles dispersed in water with a normal solid content concentration of about 5 to 40% by mass as an example, a wafer with pattern wiring was cut into 2 cm squares in a dispersion liquid of colloidal silica particles. After dipping the chip for about 30 seconds, the chip is rinsed with pure water for about 30 seconds and dried by blowing nitrogen. After that, the chip is placed on a sample table for SEM observation, an acceleration voltage of 10 kV is applied, the silica particles are observed at a magnification of 100,000 times, and an image is taken. 20 silica particles are arbitrarily selected from the obtained image, and the average particle size of those particles is taken as the average particle size.
• the number of silanol groups per 1 g of silica particles may be 10 ⁇ 10 18 /g or more, or may be 50 ⁇ 10 18 /g or more, from the viewpoint of easily obtaining an airgel having excellent shrinkage resistance. , 100 ⁇ 10 18 pieces/g or more.
• the number of silanol groups per 1 g of silica particles may be 1000 ⁇ 10 18 / g or less, 800 ⁇ 10 18 / g or less, from the viewpoint of easily obtaining a homogeneous airgel. It may be 10 18 g or less. From these viewpoints, the number of silanol groups per gram of silica particles may be 10 ⁇ 10 18 to 1000 ⁇ 10 18 /g, and may be 50 ⁇ 10 18 to 800 ⁇ 10 18 /g. , 100 ⁇ 10 18 to 700 ⁇ 10 18 /g.
• Content of polysiloxane compounds contained in the sol may be 5 parts by mass or more, or may be 10 parts by mass or more with respect to 100 parts by mass of the total amount of the sol, from the viewpoint of making it easier to obtain good reactivity.
• the content of the polysiloxane compound group contained in the sol may be 50 parts by mass or less, or 30 parts by mass or less with respect to 100 parts by mass of the total amount of the sol, from the viewpoint of making it easier to obtain good compatibility. There may be. From these points of view, the content of the polysiloxane compound group contained in the sol may be 5 to 50 parts by mass or 10 to 30 parts by mass with respect to 100 parts by mass of the total amount of the sol.
• the content of the silicon compound group (a silicon compound having a hydrolyzable functional group or a condensable functional group, and the hydrolyzable functional group
• the total content of hydrolysis products of the silicon compound having may be 5 parts by mass or more, or 7 parts by mass with respect to 100 parts by mass of the total amount of the sol, from the viewpoint of further facilitating obtaining good reactivity. or more, or 10 parts by mass or more.
• the content of the silicon compound group contained in the sol may be 50 parts by mass or less, or 40 parts by mass or less with respect to 100 parts by mass of the total amount of the sol, from the viewpoint of further facilitating obtaining good compatibility. It may be 30 parts by mass or less.
• the ratio of the content of the polysiloxane compound group and the content of the silicon compound group is 1:1 from the viewpoint of further facilitating obtaining good compatibility. It may be 0.5 or more, 1:0.7 or more, or 1:1 or more.
• the ratio of the content of the polysiloxane compound group and the content of the silicon compound group may be 1:4 or less, or 1:3 or less, from the viewpoint of further facilitating suppression of gel shrinkage. It may be 1:2 or less. From these points of view, the ratio of the content of the polysiloxane compound group to the content of the silicon compound group may be 1:0.5 to 1:4, or 1:0.7 to 1:3. It may be 1:1 to 1:2.
• the content of silica particles makes it easier to impart appropriate strength to the airgel, and from the viewpoint of making it easier to obtain an airgel with excellent shrinkage resistance during drying, the total amount of the sol is 100 parts by mass. On the other hand, it may be 1 part by mass or more, 2 parts by mass or more, or 4 parts by mass or more.
• the content of the silica particles is 20 parts by mass or less with respect to 100 parts by mass of the total amount of the sol, from the viewpoint of easily suppressing the solid heat conduction of the silica particles and easily obtaining an airgel with excellent heat insulation. It may be 17 parts by mass or less, or may be 15 parts by mass or less. From these viewpoints, the content of the silica particles may be 1 to 20 parts by mass, 2 to 17 parts by mass, or 4 to 15 parts by mass with respect to 100 parts by mass of the total amount of the sol. may
• Airgel particles in this embodiment can be obtained, for example, by pulverizing bulk airgel as described later.
• the average particle diameter D50 (also referred to as the average diameter) of the airgel particles can be 0.1 to 1000 ⁇ m, but may be 0.5 to 700 ⁇ m, may be 1 to 500 ⁇ m, and may be 3 to 100 ⁇ m. or 5 to 50 ⁇ m.
• the average particle size of the airgel particles can be appropriately adjusted by the pulverization method and pulverization conditions, sieving, classification method, and the like.
• the average particle diameter D50 of airgel particles can be measured by a laser diffraction/scattering method.
• airgel particles are dispersed by adding them to a solvent (ethanol) so that the content of the airgel particles is 0.05 to 5% by mass, and vibrating for 15 to 30 minutes with a 50W ultrasonic homogenizer. After that, about 10 mL of the dispersion liquid is injected into a laser diffraction/scattering particle size distribution analyzer, and the particle size is measured at 25° C. with a refractive index of 1.3 and an absorption of 0.
• the average particle size D50 is defined as the particle size at 50% (volume basis) of the integrated value in this particle size distribution.
• Microtrac MT3000 manufactured by Nikkiso Co., Ltd., product name
• airgel particles Commercially available products can also be used as the airgel particles.
• airgel particles include ENOVA MT1100 (manufactured by CABOT) and AeroVa (manufactured by JIOS AEROGEL CORPORATION).
• the amount of airgel particles is such that the total content of airgel particles and aggregates in the coating liquid is 70% by volume or more based on the total solid content, preferably 75% by volume. More preferably, the amount is 80% by volume or more, more preferably 80% by volume or more. Further, the amount of airgel particles, the total content of airgel particles and aggregates in the coating liquid, based on the total volume of the solid content, may be an amount such as 99% by volume or less, 95% by volume or less. It may be an amount, and it may be an amount that will be 90% by volume or less.
• the method for producing airgel particles is not particularly limited, but for example, it can be produced by the following method.
• the airgel particles of the present embodiment include a sol generation step, a wet gel generation step in which the sol obtained in the sol generation step is gelled and then aged to obtain a wet gel, and a wet gel obtained in the wet gel generation step.
• a manufacturing method mainly comprising a washing and solvent substitution step of washing and (if necessary) solvent substitution, a drying step of drying the wet gel after washing and solvent substitution, and a pulverization step of pulverizing the airgel obtained by drying can be manufactured.
• a manufacturing method mainly comprising a sol-generating step, a wet-gel-generating step, a wet-gel pulverizing step of pulverizing the wet gel obtained in the wet-gel-generating step, a washing and solvent replacement step, and a drying step.
• the obtained airgel particles can be further sized by sieving, classification, etc. Dispersibility can be improved by adjusting the size of the particles.
• the term "sol" refers to a state before a gelation reaction occurs, and in the present embodiment, it means a state in which the silicon compound and optionally silica particles are dissolved or dispersed in a solvent. .
• a wet gel means a gel solid in a wet state that does not have fluidity even though it contains a liquid medium.
• the sol-producing step is a step of mixing a silicon compound and optionally silica particles (which may be a solvent containing silica particles), hydrolyzing the mixture, and then producing a sol.
• an acid catalyst may be further added to the solvent in order to promote the hydrolysis reaction.
• a surfactant, a thermally hydrolyzable compound, etc. can be added to the solvent.
• components such as carbon graphite, an aluminum compound, a magnesium compound, a silver compound, and a titanium compound may be added to the solvent.
• Alcohols include methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-butanol, t-butanol and the like.
• methanol, ethanol, 2-propanol, and the like are listed as alcohols having a low surface tension and a low boiling point in terms of reducing the interfacial tension with the gel wall. These may be used alone or in combination of two or more.
• the amount of alcohol when used as a solvent, can be 4 to 8 mol with respect to 1 mol of the total amount of the silicon compound group and the polysiloxane compound group, but it may be 4 to 6.5, Or it may be 4.5 to 6 mol.
• the amount of alcohol is 4 mol or more, it becomes easier to obtain good compatibility, and when it is 8 mol or less, it becomes easier to suppress gel shrinkage.
• Acid catalysts include inorganic acids such as hydrofluoric acid, hydrochloric acid, nitric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, hypophosphorous acid, bromic acid, chloric acid, chlorous acid, and hypochlorous 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 can be mentioned as an acid catalyst that further improves the water resistance of the resulting airgel.
• the organic carboxylic acid includes acetic acid, but may also be formic acid, propionic acid, oxalic acid, malonic acid, or the like. These may be used alone or in combination of two or more.
• the hydrolysis reaction of the silicon compound can be accelerated and the sol can be obtained in a shorter time.
• the amount of the acid catalyst added can be 0.001 to 0.1 parts by mass with respect to 100 parts by mass as the total amount of the polysiloxane compound group and the silicon compound group.
• nonionic surfactants ionic surfactants, etc.
• ionic surfactants etc.
• these may be used alone or in combination of two or more.
• nonionic surfactant for example, a compound containing a hydrophilic part such as polyoxyethylene and a hydrophobic part mainly composed of an alkyl group, a compound containing a hydrophilic part such as polyoxypropylene, etc. can be used.
• examples of compounds containing a hydrophilic portion such as polyoxyethylene and a hydrophobic portion mainly composed of alkyl groups include polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene alkyl ether and the like.
• Compounds containing hydrophilic moieties such as polyoxypropylene include polyoxypropylene alkyl ethers, block copolymers of polyoxyethylene and polyoxypropylene, and the like.
• ionic surfactants include cationic surfactants, anionic surfactants, and amphoteric surfactants.
• cationic surfactants include cetyltrimethylammonium bromide and cetyltrimethylammonium chloride
• anionic surfactants include sodium dodecylsulfonate.
• Amphoteric surfactants include amino acid-based surfactants, betaine-based surfactants, amine oxide-based surfactants, and the like.
• amino acid-based surfactants include acylglutamic acid and the like.
• betaine surfactants include betaine lauryldimethylaminoacetate and betaine stearyldimethylaminoacetate.
• Amine oxide surfactants include, for example, lauryldimethylamine oxide.
• the amount of the surfactant added depends on the type of surfactant or the type and amount of the silicon compound, but for example, 1 to 100 parts by weight per 100 parts by weight of the total amount of the polysiloxane compound group and the silicon compound group. can be The amount of addition may be 5 to 60 parts by mass.
• thermohydrolyzable compound is not particularly limited as long as it is a compound capable of making the reaction solution basic after hydrolysis.
• Urea formamide, N-methylformamide, N,N-dimethylformamide, acetamide, N acid amides such as -methylacetamide and N,N-dimethylacetamide; and cyclic nitrogen compounds such as hexamethylenetetramine.
• urea is particularly easy to obtain the above promotion effect.
• the amount of the thermally hydrolyzable compound to be added is not particularly limited as long as it is an amount that can sufficiently promote the sol-gel reaction in the wet gel formation step described later.
• the amount added can be 1 to 200 parts by mass with respect to 100 parts by mass as the total amount of the polysiloxane compound group and the silicon compound group.
• the addition amount may be 2 to 150 parts by mass.
• An addition amount of 1 part by mass or more makes it easier to obtain good reactivity, and an addition amount of 200 parts by mass or less makes it easier to suppress crystal precipitation and a decrease in gel density.
• Hydrolysis in the sol generation step depends on the types and amounts of silicon compounds, silica particles, acid catalysts, surfactants, etc. in the mixed liquid, but for example, it takes 10 minutes to 24 minutes in a temperature environment of 20 to 60 ° C. It may be carried out for 5 minutes to 8 hours in a temperature environment of 50 to 60°C. As a result, the hydrolyzable functional groups in the silicon compound are sufficiently hydrolyzed, and the hydrolysis product of the silicon compound can be obtained more reliably.
• the temperature environment in the sol formation step may be adjusted to a temperature that suppresses hydrolysis of the thermally hydrolyzable compound and gelation of the sol. .
• the temperature at this time may be any temperature as long as it can suppress the hydrolysis of the thermally hydrolyzable compound.
• the temperature environment in the sol formation step can be 0 to 40°C, but may be 10 to 30°C.
• the wet gel forming step is a step of gelling the sol obtained in the sol forming step and then aging it to obtain a wet gel.
• a base catalyst can be used to promote gelation.
• Basic catalysts include carbonates such as calcium carbonate, potassium carbonate, sodium carbonate, barium carbonate, magnesium carbonate, lithium carbonate, ammonium carbonate, copper (II) carbonate, iron (II) carbonate, and silver carbonate (I); Hydrogen carbonates such as calcium, potassium hydrogen carbonate, sodium hydrogen carbonate and ammonium hydrogen carbonate; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide and cesium hydroxide; ammonium hydroxide, ammonium fluoride, Ammonium compounds such as ammonium chloride and ammonium bromide; basic sodium phosphate salts such as sodium metaphosphate, sodium pyrophosphate and sodium polyphosphate; allylamine, diallylamine, triallylamine, isopropylamine, diisopropylamine, ethylamine, diethylamine, triethylamine, 2 -ethylhexylamine, 3-ethoxypropylamine, diisobutyl
• ammonium hydroxide (aqueous ammonia) is highly volatile and does not easily remain in airgel particles after drying, so it is less likely to impair water resistance and is excellent in terms of economy.
• the above basic catalysts may be used alone or in combination of two or more.
• the dehydration condensation reaction or dealcoholization condensation reaction of the silicon compound and silica particles in the sol can be promoted, and the sol can be gelled in a shorter time.
• this makes it possible to obtain a wet gel with higher strength (rigidity).
• ammonia is highly volatile and hardly remains in the airgel particles, airgel particles with more excellent water resistance can be obtained by using ammonia as the basic catalyst.
• the amount of the basic catalyst to be added can be 0.5 to 5 parts by mass with respect to 100 parts by mass as the total amount of the polysiloxane compound group and the silicon compound group, but it may be 1 to 4 parts by mass. When the amount is 0.5 parts by mass or more, gelation can be performed in a shorter time, and when the amount is 5 parts by mass or less, deterioration of water resistance can be further suppressed.
• the gelation of the sol in the wet gel formation process may be performed in a closed container so that the solvent and basic catalyst do not volatilize.
• the gelation temperature can be 30-90°C, but may be 40-80°C.
• gelation temperature 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.
• volatilization of the solvent especially alcohol
• Aging in the wet gel formation process may be performed in a closed container so that the solvent and basic catalyst do not volatilize. Aging strengthens the bonding of the components constituting the wet gel, and as a result, a wet gel having sufficient strength (rigidity) to suppress shrinkage during drying can be obtained.
• the aging temperature can be 30-90°C, but may be 40-80°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 alcohol) can be easily suppressed. , it is possible to gel while suppressing volumetric shrinkage.
• the gelling of the sol and the subsequent aging may be performed in a continuous series of operations.
• the gelling time and aging time can be appropriately set according to the gelling temperature and aging temperature.
• the gelation time can be particularly shortened compared to when the sol is not contained. The reason for this is presumed to be that the silanol groups or reactive groups of the silicon compound in the sol form hydrogen bonds or chemical bonds with the silanol groups of the silica particles.
• the gelling time can be 10 to 120 minutes, but may be 20 to 90 minutes. A gelation time of 10 minutes or more makes it easier to obtain a homogeneous wet gel, and a gelation time of 120 minutes or less makes it possible to simplify the washing and solvent replacement steps and the drying steps, which will be described later.
• the total time of the gelling and aging steps can be 4 to 480 hours, but may be 6 to 120 hours.
• a wet gel with higher strength (rigidity) can be obtained by setting the total time of gelling time and aging time to 4 hours or more, and the effect of aging can be more easily maintained by setting the total time to 480 hours or less.
• the gelation temperature and aging temperature are increased within the above range, and the total time of gelation time and aging time is increased within the above range. good too.
• the gelation temperature and aging temperature are lowered within the above range, or the total time of gelation time and aging time is within the above range. You can shorten it.
• the wet gel obtained in the wet gel production step is pulverized. Pulverization can be carried out, for example, by putting the wet gel in a Henshall type mixer, or performing a wet gel forming step in the mixer and operating the mixer under appropriate conditions (rotation speed and time). Alternatively, more simply, the wet gel is placed in a sealable container, or the wet gel formation step is performed in a sealable container and shaken for an appropriate amount of time using a shaking device such as a shaker. can be done. If necessary, the particle size of the wet gel can be adjusted using a jet mill, roller mill, bead mill, or the like.
• the washing and solvent replacement step includes a step of washing the wet gel obtained by the wet gel generation step or the wet gel pulverization step (washing step), and washing the washing liquid in the wet gel with a solvent suitable for drying conditions (drying step described later). (solvent replacement step).
• 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.
• the wet gel may be washed from the viewpoint of enabling production of airgel particles with high purity.
• the wet gel obtained by the wet gel generation step or the wet gel crushing step is washed.
• the washing can be repeated using, for example, water or an organic solvent. At this time, the cleaning 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, dimethylsulfoxide, acetic acid, formic acid and the like can be used.
• the above organic solvents may be used alone or in combination of two or more.
• the organic solvent used in the washing step includes a hydrophilic organic solvent having high mutual solubility in both water and the low surface tension solvent.
• the hydrophilic organic solvent used in the washing step can serve as preliminary replacement for the solvent replacement step.
• hydrophilic organic solvents include methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone and the like.
• methanol, ethanol, methyl ethyl ketone, etc. are excellent in terms of economy.
• the amount of water or organic solvent used in the washing step can be an amount that can sufficiently replace the solvent in the wet gel and wash.
• the amount can be 3 to 10 times the volume of the wet gel. Washing can be repeated until the water content in the wet gel after washing is 10% by mass or less relative to the mass of silica.
• the temperature environment in the washing process can be a temperature below the boiling point of the solvent used for washing.
• the solvent of the washed wet gel is replaced with a predetermined replacement solvent in order to suppress the shrinkage of the airgel during the drying process.
• the replacement efficiency can be improved by heating.
• Specific examples of the replacement solvent include low surface tension solvents described below when drying is performed under atmospheric pressure at a temperature below the critical point of the solvent used for drying in the drying step.
• the replacement solvent includes, for example, ethanol, methanol, 2-propanol, dichlorodifluoromethane, carbon dioxide, or a mixture of two or more thereof.
• Solvents with low surface tension include solvents with a surface tension of 30 mN/m or less at 20°C. The surface tension may be 25 mN/m or less, or 20 mN/m or less.
• Examples of low surface tension solvents 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); benzene (28.9), toluene (28.5), m-xylene (28.7), p-xylene (28.3) and other aromatic hydrocarbons; dichloromethane (27.9), chloroform (27.2) ), carbon tetrachloride (26.9), 1-chloropropane (21.8), 2-chloropropan
• aliphatic hydrocarbons hexane, heptane, etc.
• hydrophilic organic solvents such as acetone, methyl ethyl ketone, and 1,2-dimethoxyethane can be used as organic solvents in the washing step.
• a solvent having a boiling point of 100° C. or lower under normal pressure may be used because it can be easily dried in the drying step to be described later.
• the above solvents may be used alone or in combination of two or more.
• the amount of solvent used in the solvent replacement step can be an amount sufficient to 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 below the boiling point of the solvent used for replacement.
• the solvent replacement step is not essential.
• the presumed mechanism is as follows. That is, the silica particles function as a support for the three-dimensional network skeleton, thereby supporting the skeleton and suppressing shrinkage of the gel during the drying process. Therefore, it is considered that the gel can be directly subjected to the drying process without replacing the solvent used for washing. Thus, by using silica particles, it is possible to simplify the washing and solvent replacement steps and the drying step.
• the drying method is not particularly limited, and known normal pressure drying, supercritical drying or freeze drying can be used.
• normal pressure drying or supercritical drying can be used from the viewpoint of easy production of low-density airgel.
• normal pressure drying can be used from the viewpoint of low-cost production.
• normal pressure means 0.1 MPa (atmospheric pressure).
• the airgel can be obtained by drying the washed and (if necessary) solvent-substituted wet gel under atmospheric pressure at a temperature below the critical point of the solvent used for drying.
• the drying temperature depends on the type of solvent replaced (or the solvent used for washing if solvent replacement is not performed), especially if drying at high temperature accelerates the evaporation rate of the solvent and causes large cracks in the gel.
• the drying temperature may be 60 to 120°C.
• the drying time varies depending on the volume of the wet gel and the drying temperature, but can be 4 to 120 hours. It should be noted that normal pressure drying also includes speeding up drying by applying a pressure below the critical point within a range that does not impede productivity.
• Aerogels can also be obtained by supercritical drying of washed and (optionally) solvent-exchanged wet gels.
• 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 above the critical point of the solvent contained in the wet gel.
• the wet gel is immersed in liquefied carbon dioxide under conditions of, for example, 20 to 25 ° C. and 5 to 20 MPa, so that all or part of the solvent contained in the wet gel is is replaced with carbon dioxide having a lower critical point than the solvent, and then carbon dioxide alone or a mixture of carbon dioxide and the solvent is removed.
• the airgel obtained by such normal pressure drying or supercritical drying may be additionally dried at 105 to 200°C for about 0.5 to 2 hours under normal pressure. This makes it easier to obtain aerogels with low densities and small pores. Additional drying may be performed at 150 to 200° C. under normal pressure.
• airgel particles are obtained by pulverizing the airgel (airgel block) obtained by drying.
• it can be carried out by putting the airgel in a jet mill, roller mill, bead mill, hammer mill or the like and operating it at an appropriate rotation speed and time.
• the emulsion may be obtained by emulsifying a binder resin in a liquid medium with a polymeric emulsifier.
• the aqueous solvent may contain an organic solvent in addition to water. Any organic solvent may be used as long as it is compatible with water. Examples include alcohols such as methanol, ethanol, isopropanol, butanol, ethylene glycol, and propylene glycol; ethers such as diethyl ether, tetrahydrofuran, and 1,4-dioxane. ketones such as acetone and methyl ethyl ketone; carboxylic acids such as acetic acid and propionic acid; and nitrogen-containing compounds such as acetonitrile, dimethylformamide and triethylamine.
• the content of the liquid medium in the emulsion is not particularly limited.
• the content of the liquid medium in the coating liquid is not particularly limited, and may be changed as appropriate according to the desired viscosity of the coating liquid.
• the content of the liquid medium in the coating liquid may be such that the solid content concentration of the coating liquid is within the preferred range described below.
• the liquid medium in the coating liquid may be only the liquid medium in the emulsion, or may include the liquid medium added during or after mixing the emulsion and the airgel particles.
• the solid content concentration of the coating liquid may be, for example, 10% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more. Further, the solid content concentration of the coating liquid may be, for example, 70% by mass or less, preferably 60% by mass or less, and more preferably 50% by mass or less.
• the binder resin may be any resin that can be emulsified with a polymer emulsifier in a liquid medium.
• binder resins include urethane resins, alkyd resins, silicone resins, acrylic resins, olefin resins, fluorine resins, vinyl acetate resins, vinyl chloride resins, polyesters, polyamides, polyimides, and two or more types of monomers that form these resins.
• a copolymer of Among these, ethylene-vinyl acetate copolymers, ethylene-vinyl chloride copolymers, acrylic resins, and silicone resins can be preferably used from the standpoint of better flexibility of the heat insulating material to be formed.
• a vinyl acetate resin can be preferably used from the viewpoint of excellent film formability.
• the content of the binder resin in the emulsion is not particularly limited, and may be, for example, 20% by mass or more, or 30% by mass or more. Also, the content of the binder resin in the emulsion may be, for example, 80% by mass or less, or may be 60% by mass or less.
• the content of the binder resin in the coating liquid may be, for example, 30% by volume or less, preferably 25% by volume or less, more preferably 20% by volume or less, based on the total solid content.
• the content of the binder resin in the coating liquid may be, for example, 1% by volume or more, 5% by volume or more, or 10% by volume or more, based on the total solid content. .
• the polymeric emulsifier may be any emulsifier that can emulsify the binder resin in the liquid medium.
• the term "polymeric emulsifier” refers to an emulsifier formed by polymerizing a monomer (and modifying the polymer if necessary).
• the polymeric emulsifier may have a molecular weight distribution.
• the number average molecular weight (Mn) of the polymeric emulsifier is, for example, 1,000 or more, and may be 5,000 or more, 8,000 or more, 10,000 or more, or 20,000 or more. Further, the number average molecular weight of the polymeric emulsifier is, for example, 1,000,000 or less, and may be 50,000 or less, 200,000 or less, 100,000 or less, or 50,000 or less. In addition, the number average molecular weight of a polymeric emulsifier shows the value measured by GPC.
• polymeric emulsifiers examples include polyvinyl alcohol (PVA) and hydroxyethyl cellulose.
• the content of the polymeric emulsifier in the emulsion may be, for example, 0.001 parts by mass or more with respect to 100 parts by mass of the binder resin. 05 parts by mass or more, or 0.1 parts by mass or more.
• the content of the polymeric emulsifier in the emulsion may be, for example, 80 parts by mass or less with respect to 100 parts by mass of the binder resin. It can be less than part.
• the content of the polymeric emulsifier in the coating liquid may be, for example, 0.0001 parts by mass or more with respect to 100 parts by mass of the binder resin, and from the viewpoint of stabilizing the emulsion, 0.001 parts by mass or more, It may be 0.005 parts by weight or more, or 0.01 parts by weight or more.
• the content of the polymeric emulsifier in the coating liquid may be, for example, 80 parts by mass or less with respect to 100 parts by mass of the binder resin. It may be not more than 5 parts by mass or not more than 5 parts by mass.
• the method of producing the emulsion is not particularly limited, and examples include a method of synthesizing a binder resin in the presence of a polymeric emulsifier in a liquid medium.
• the emulsion may further contain other ingredients than those mentioned above.
• Other components include, for example, fillers, solvents, pigments, dyes, preservatives, antifoaming agents and the like.
• the coating liquid of this embodiment may further contain a water-soluble polymer having a hydrophobic group.
• the water-soluble polymer should just have a hydrophobic group and be water-soluble.
• the water-soluble polymer may be added during or after mixing the emulsion and airgel particles.
• hydrophobic groups include alkyl groups (preferably long-chain alkyl groups with 6 to 26 carbon atoms), ester groups, alkoxy groups, and halogens.
• the hydrophobic group is preferably an alkyl group, more preferably a long-chain alkyl group having 8 to 26 carbon atoms, more preferably a long-chain alkyl group having 10 to 26 carbon atoms, further preferably 12 to 26 carbon atoms.
• a long-chain alkyl group of is more preferable, and a long-chain alkyl group having 15 to 26 carbon atoms may be used.
• water-soluble polymers examples include modified carboxyvinyl polymer, modified polyether urethane, cellulose resin, polyethylene oxide, polyvinyl alcohol, polyacrylate, polyvinylpyrrolidone, dextrin resin, chitin resin, chitosan resin, and the like. mentioned.
• a cellulose-based resin can be suitably used as the water-soluble polymer.
• Cellulosic resins include, for example, methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and modified products obtained by further modifying (for example, hydrophobizing) these.
• a cellulose-based resin having an alkyl group is preferable, and a cellulose-based resin having a long-chain alkyl group having 6 to 26 carbon atoms is more preferable. According to such a cellulose-based resin, the effects of the present invention are exhibited more remarkably.
• the number of carbon atoms in the long-chain alkyl group is preferably 8-26, more preferably 10-26, even more preferably 12-26, still more preferably 15-26.
• cellulose-based resin for example, a cellulose-based resin having a structural unit represented by the following formula (A-1) is preferable.
• R A is a hydrogen atom, an alkyl group, a hydroxyalkyl group, or a group represented by -R A1 -OR A2 (R A1 represents an alkanediyl group or a hydroxyalkanediyl group, R A2 represents an alkyl group.).
• Three RAs may be the same or different. However, at least one of the three R A is an alkyl group or a group represented by -R A1 -OR A2 .
• an alkyl group having 1 to 26 carbon atoms is preferable.
• the alkyl group in RA is more preferably a short-chain alkyl group having 1 to 3 carbon atoms or a long-chain alkyl group having 6 to 26 carbon atoms.
• the carbon number of the long-chain alkyl group is preferably 8-26, more preferably 10-26, even more preferably 12-26, still more preferably 15-26.
• the hydroxyalkyl group in R A is preferably a hydroxyalkyl group having 1 to 26 carbon atoms, more preferably a hydroxyalkyl group having 1 to 10 carbon atoms, and a hydroxyalkyl group having 1 to 5 carbon atoms. groups are more preferred.
• the alkanediyl group in R A1 is preferably an alkanediyl group having 1 to 26 carbon atoms, more preferably an alkanediyl group having 1 to 10 carbon atoms, and still more preferably an alkanediyl group having 1 to 10 carbon atoms. 1 to 5 alkanediyl groups.
• the hydroxyalkanediyl group in R A1 is preferably a hydroxyalkanediyl group having 1 to 26 carbon atoms, more preferably a hydroxyalkanediyl group having 1 to 10 carbon atoms, and still more preferably 1 to 5 carbon atoms. is a hydroxyalkanediyl group of
• R A2 is preferably an alkyl group having 1 to 26 carbon atoms.
• the alkyl group in R A2 is more preferably a short-chain alkyl group having 1 to 3 carbon atoms or a long-chain alkyl group having 6 to 26 carbon atoms, more preferably a long-chain alkyl group.
• the carbon number of the long-chain alkyl group is preferably 8-26, more preferably 10-26, even more preferably 12-26, still more preferably 15-26.
• At least one of the three R A is a long-chain alkyl group, or at least one of the three R A is a group represented by -R A1 -OR A2 . and RA2 is a long-chain alkyl group.
• the content of long-chain alkyl groups having 6 to 26 carbon atoms is preferably 0.01 to 5% by mass, more preferably 0.01 to 3% by mass, based on the total amount of the cellulose resin. is more preferred.
• the content of the water-soluble polymer in the coating liquid may be, for example, 0.01% by volume or more, preferably 0.1% by volume or more, based on the total solid content in the coating liquid. , more preferably 0.3% by volume or more.
• the content of the water-soluble polymer may be, for example, 10% by volume or less, preferably 5% by volume or less, and more preferably 3% by volume or less, based on the total solid content in the coating liquid. be.
• the coating liquid of the present embodiment may further contain thickeners, fibrous substances, pigments, leveling agents, etc., as components other than those described above.
• thickeners include fine particles such as fumed silica and clay minerals.
• Fibrous substances can exhibit an anchor function between airgel particles, and can further improve the strength of the composite material coating.
• the fibrous substance is not particularly limited and includes organic fibers and inorganic fibers.
• organic fibers include polyamide fibers, polyimide fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, polyester fibers, polyacrylonitrile fibers, polyethylene fibers, polypropylene fibers, and polyurethane. fiber, phenol-based fiber, polyetherester-based fiber, polylactic acid-based fiber, polycarbonate-based fiber, and the like.
• inorganic fibers include glass fibers, carbon fibers, ceramic fibers, and metal fibers.
• the coating liquid includes a preparation step of preparing an emulsion containing a polymer emulsifier, a binder resin and a liquid medium, and airgel particles, and mixing the emulsion and airgel particles prepared in the preparation step. , and a mixing step of aggregating at least part of the airgel particles to obtain a coating liquid containing agglomerates of airgel particles, a polymeric emulsifier, a binder resin and a liquid medium.
• components other than the emulsion and airgel particles may be further prepared.
• each component prepared in the preparation process is mixed so that the airgel particles aggregate.
• the mixing method may be any method as long as the airgel particles can form aggregates, for example, a method of stirring and mixing each component prepared in the preparation step.
• the stirring speed affects the size of aggregates.
• the larger the stirring speed the more shear stress is applied to the coating liquid, so the size of aggregates tends to decrease. Therefore, from the viewpoint of obtaining aggregates of a suitable size, which will be described later, it is desirable to prepare the coating liquid at a low stirring speed.
• the viscosity during mixing also affects the size of the aggregates. Even if the stirring speed is the same, the shear stress applied to the coating liquid changes depending on the viscosity. The higher the viscosity, the greater the shear stress applied to the coating fluid and the smaller the size of the agglomerates. On the other hand, if the viscosity of the coating liquid is low, the shear stress applied to the coating liquid will be small even if the stirring speed is the same, and the size of the aggregates will increase. Therefore, by adjusting the stirring speed according to the viscosity of the coating liquid, it is possible to prepare a coating liquid having a desired aggregate size.
• Additives that strongly affect aggregate size include surface modifiers, surfactants, dispersants, and the like.
• Surface modifiers and surfactants reduce the surface energy between the airgel particles and the solution. The lower the surface energy, the weaker the force that tends to reduce the interface, and the size of aggregates tends to be smaller. Therefore, the addition of surface modifiers and surfactants lowers the surface energy and reduces the size of aggregates.
• the dispersant By adhering to the particle surface, the dispersant suppresses the approach of particles by electrostatic or steric repulsion. Since the dispersant adheres to the surface of the airgel particles and suppresses the approach of the airgel particles, the addition of the dispersant reduces the size of the aggregates.
• the amount of liquid medium during mixing also affects the size of aggregates. Even if the composition of the finally manufactured coating liquid is the same, (i) a method in which the entire amount of the liquid medium is added from the beginning of mixing, and (ii) a method in which a small amount of the liquid medium is added at the beginning of mixing, and then the liquid medium is added, the size of the aggregates is different. Compared to the method (i), the method (ii) has a higher initial viscosity of the coating liquid, and the concentration of the above-mentioned additive becomes higher when the additive is added. Therefore, the above method (ii) tends to result in a smaller aggregate size than the above method (i). Aggregates of a desired size can be formed by properly using these methods according to conditions such as the composition of the coating liquid and the mixing device (stirring device).
• aggregates with a diameter of 20 ⁇ m or more are preferably formed, more preferably aggregates with a diameter of 40 ⁇ m or more are formed, and aggregates with a diameter of 50 ⁇ m or more are formed. More preferably.
• the diameter of aggregates is preferably 400 ⁇ m or less, more preferably 300 ⁇ m or less.
• the average diameter of the aggregates is preferably at least twice the average diameter of the airgel particles prepared in the preparation step, more preferably at least 4 times, and at least 8 times. More preferred. As a result, the contact interface between the airgel and the resin component becomes smaller, and the permeation of the resin component into the pores of the airgel is more easily suppressed.
• the average diameter of the aggregates is preferably 40 times or less, more preferably 30 times or less, more preferably 20 times or less than the average diameter of the airgel particles prepared in the preparation step. This suppresses a decrease in film strength due to continuous relatively brittle airgel, and makes it easier to obtain higher film strength.
• the average diameter of aggregates indicates a value measured by the following method.
• Method for measuring average diameter of aggregates in coating liquid About 20 g of the coating liquid is placed in a 100 mL plastic cup, and 2 g of water is added at a time while stirring using a spatula to dilute while gradually blending. A diluted sample is placed on a glass plate, and a photomicrograph of the sample is obtained using an optical microscope (manufactured by OLYMPUS, model number: BX51). The micrographs obtained are analyzed using image editing software ImageJ to determine the diameters of multiple aggregates in the micrographs. The average value of the obtained values is taken as the average diameter of aggregates.
• the average diameter of the airgel particles is synonymous with the average particle diameter D50 of the airgel particles described above.
• the area occupied by aggregates is preferably 50% or more, more preferably 60% or more, even more preferably 70% or more, and may be 100%.
• the diluted solution of the coating solution and the observation method of the diluted solution are the samples prepared in the above [Method for measuring the average diameter of aggregates in the coating solution] and the observation method of the sample. can be the same. Also, the "area within the observation field" is obtained by analyzing the micrograph using image editing software ImageJ.
• the heat insulating material includes a coating step of applying the coating liquid on a support to obtain a coating film, a removal step of removing at least part of the liquid medium from the coating film to obtain a heat insulating material, Manufactured by a manufacturing method comprising According to this manufacturing method, agglomerates of airgel particles are formed in the coating liquid, and the penetration of the resin into the airgel pores is sufficiently suppressed, so that the heat insulating material has high heat insulation and high film-forming properties. is obtained.
• the support to which the coating liquid is applied is not particularly limited.
• the support may be peeled from the insulating material after the insulating material is manufactured, or may be used without being peeled from the insulating material.
• the support may, for example, be the subject of thermal insulation.
• Materials constituting the support are not particularly limited, and may be, for example, metals, ceramics, glass, resins, composite materials thereof, and the like.
• the form of the support may be appropriately selected according to the intended use, material, etc., and may be, for example, block-like, sheet-like, powder-like, fiber-like, and the like.
• the method of applying the coating liquid is not particularly limited, and examples thereof include dip coating, spray coating, spin coating, and roll coating.
• the method of applying the coating liquid may be a method in which the pressure applied to the coating liquid is 1.5 MPa or less. According to such a coating method, crushing of aggregates in the coating liquid due to load during coating is suppressed.
• a coating method such as roller coating, trowel coating, or air spraying is preferable because the pressure applied to the coating liquid can be easily reduced.
• the binder resin in the emulsion is covered with the polymer emulsifier, so that the fine particles of the binder resin and the aggregates of the airgel particles are difficult to contact, and the airgel particles It is difficult for the binder resin to enter the gaps in the aggregates, and the aggregates of the airgel particles are difficult to collapse.
• a coating method in which the pressure applied to the coating liquid exceeds 1.5 MPa can also be suitably used as the coating method of the coating liquid. Examples of such a coating method include coating with an airless spray, a die coater, a lip coater, and the like.
• a heat insulating material made of a composite material containing airgel particle aggregates, a binder resin, and a polymeric emulsifier is formed.
• the method of removing the liquid medium from the coating film is not particularly limited, and examples thereof include heating (eg, 40 to 150°C) treatment, depressurization (eg, 10,000 Pa or less) treatment, or a method of performing both of these treatments.
• the thickness of the heat insulating material is not particularly limited, and may be, for example, 0.01 to 30 mm, or 0.1 to 20 mm.
• the insulating material has pores caused by airgel particles.
• the pore volume of the heat insulating material is preferably 0.15 cm 3 /g or more, more preferably 0.20 cm 3 /g or more, and even more preferably 0.60 cm 3 /g or more, from the viewpoint of obtaining higher heat insulation.
• the upper limit of the pore volume of the heat insulating material is not particularly limited.
• the pore volume of the insulating material may be, for example, 5.0 cm 3 /g or less.
• the thermal conductivity of the heat insulating material is, for example, 0.05 W/(m ⁇ K) or less, preferably 0.04 W/(m ⁇ K) or less, more preferably 0.035 W/(m ⁇ K) or less. .
• the lower limit of the thermal conductivity of the heat insulating material is not particularly limited.
• the thermal conductivity of the heat insulating material may be, for example, 0.01 W/(m ⁇ K) or more.
• the heat insulating material produced by the production method of this embodiment has excellent heat insulating properties, heat resistance, flame retardancy, etc. derived from airgel. Therefore, the heat insulating material can be applied to cryogenic containers, the field of space, the field of construction, the field of automobiles, the field of home electric appliances, the field of semiconductors, the use as a heat insulating material in industrial facilities, and the like.
• the heat insulating material can also be used as a water repellent material, a sound absorbing material, a vibration damping material, a catalyst supporting material, and the like.
• Example 1 In a 500 mL separable flask, 6 parts by mass of Sangelose 90 L (manufactured by Daido Kasei Co., Ltd.) as a water-soluble polymer, 46 parts by mass of isopropyl alcohol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., reagent), 840 parts by mass of hot water The solution was removed and stirred at 200 rpm for 1 minute using a mechanical stirrer to obtain a dispersion liquid.
• Sangelose 90 L manufactured by Daido Kasei Co., Ltd.
• isopropyl alcohol manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., reagent
• airgel particles manufactured by CABOT, product name: ENOVA MT1100, particle diameter 2-24 ⁇ m, average particle diameter (D50) 10 ⁇ m
• the vinyl acetate emulsion was prepared by using polyvinyl alcohol (degree of polymerization: 1700) as a polymeric emulsifier in the same manner as in Example 1 of JP-B-6-18966.
• the content of airgel particles is 74.7% by volume
• the content of water-soluble polymer is 0.4% by volume
• the content of vinyl acetate resin is 24.9% by volume. Met.
• Example 2 The procedure was the same as in Example 1, except that the vinyl acetate emulsion was changed to an ethylene-vinyl acetate copolymer emulsion (manufactured by Sumika Chemtex Co., Ltd., product name: Sumikaflex 400HQ) produced using a polyvinyl alcohol-based emulsifier. to obtain the coating liquid.
• the content of airgel particles is 72.9% by volume
• the content of water-soluble polymer is 0.4% by volume
• the content of ethylene-vinyl acetate copolymer resin The amount was 26.7% by volume.
• Example 3 Example 1, except that the vinyl acetate emulsion was changed to an ethylene-vinyl acetate-vinyl chloride copolymer emulsion (manufactured by Sumika Chemtex, product name: Sumikaflex 801HQ) produced using a polyvinyl alcohol-based emulsifier.
• a coating liquid was obtained in the same manner. In the coating liquid, based on the total solid content, the content of airgel particles is 74.7% by volume, the content of water-soluble polymer is 0.4% by volume, and the ethylene-vinyl acetate-vinyl chloride copolymer The resin content was 24.9% by volume.
• Example 1 (Comparative example 1) Except that the vinyl acetate emulsion was changed to an acrylic silicone emulsion produced using a radically polymerizable emulsifier (manufactured by ADEKA, product name: Adekari Soap SE-10N) in the same manner as in Example 1 of JP-A-11-80486. obtained a coating liquid in the same manner as in Example 1.
• the content of airgel particles is 76.6% by volume
• the content of water-soluble polymer is 0.4% by volume
• the content of acrylic silicone resin is 23.0%. % by volume.
• a heat insulating material was produced by the same method as the above ⁇ Evaluation of cracks in heat insulating material>. 100 mg of the produced heat insulating material was sampled, and the pore volume was calculated using a highly sensitive gas adsorption analyzer (AutoSorb iQ manufactured by Quantachrome).
• ⁇ Evaluation of thermal conductivity of heat insulating material> Prepare a frame of 200 mm in length and width and 3 mm in thickness made of fluororesin on aluminum foil (manufactured by UACJ Co., Ltd., product name: My Foil Thick Type 50, thickness: 50 ⁇ m), and apply the coating liquid inside the frame using a spatula. applied. The liquid medium was removed from the coating liquid by allowing it to stand at room temperature of 23° C. for 12 hours to obtain a heat insulating material. The thermal conductivity of the obtained heat insulating material was measured by a steady-state method using a thermal conductivity measuring device "HFM-446" (manufactured by NETZSCH, product name).
• Table 1 shows the results of the above evaluation.

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