Insulating paints, insulating coatings, and insulating materials

Abstract

To provide a coating material for a heat insulating material which has excellent dispersibility of a silica aerogel and good coatability, and from which a heat insulating coating film having high durability and excellent heat insulating properties can be formed, and to provide a heat insulating coating film and a heat insulating material obtained from the coating material for a heat insulating material.SOLUTION: The coating material for a heat insulating material of the present invention comprises a silica aerogel (A), a urethane resin emulsion (B), a cellulose nanofiber (C), a nonionic surfactant (D), and water, wherein when the solid content mass of the urethane resin emulsion (B) is B (pts.mass) and the solid content mass of the cellulose nanofiber (C) is C (pts.mass), the value of B / C is 0.5 or more and 20 or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a paint for heat insulating materials, a heat insulating coating film, and a heat insulating material.

Background Art

[0002] Conventionally, since energy conservation has been strongly promoted, the heat insulating function required for heat insulating materials has been increasing year by year. Heat insulating materials are indispensable materials in various fields such as buildings such as houses, buildings, and factories, vehicles such as automobiles, and electronic devices. As heat insulating materials, various materials such as inorganic fiber bodies, inorganic foams, and resin-based foams are known, and silica aerogel is one of them.

[0003] Silica aerogel has a structure in which a large number of silica fine particles are connected to each other, so it has a very high porosity and excellent heat insulating properties. Therefore, the development of heat insulating materials that utilize such properties of silica aerogel has been actively carried out. Various heat insulating materials containing silica aerogel are known, and one of them is a heat insulating material obtained from a paint for heat insulating materials containing silica aerogel.

[0004] For example, Patent Document 1 discloses that a paint for a heat insulating material having water, silica aerogel, a water-soluble binder, and nanofibers is applied to a substrate to form a silica aerogel-containing coating film on the substrate, and this is used as a heat insulating material. Such a paint for a heat insulating material has hydrophilic nanofibers present around the silica aerogel, so that the silica aerogel is more compatible with water. As a result, the dispersibility of the silica aerogel is improved and high heat insulating properties can be obtained.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, increasingly high demands have been placed on thermal insulation materials, and there is a need to improve their thermal insulation performance as much as possible. The same applies to thermal insulation coatings containing silica aerogel, as mentioned above, and it is urgent to further improve the thermal insulation performance of the thermal insulation materials obtained from such coatings. Therefore, the challenge for thermal insulation coatings containing silica aerogel is how to further improve the dispersibility of silica aerogel and how to improve the durability of the coating obtained from the thermal insulation coating.

[0007] The present invention has been made in view of the above, and aims to provide a paint for thermal insulation that has excellent dispersibility of silica aerogel, good coating properties, and can form a thermal insulation coating film that has high durability and excellent thermal insulation properties. The present invention also aims to provide a thermal insulation coating film and thermal insulation material obtained from a paint for thermal insulation. [Means for solving the problem]

[0008] The inventors of this invention conducted extensive research to achieve the above objectives and, as a result, discovered that the above objectives can be achieved by including a urethane resin emulsion and cellulose nanofibers in a predetermined ratio, and by using a nonionic surfactant in combination, thus completing the present invention.

[0009] In other words, the present invention encompasses, for example, the subject matter described in the following sections. Item 1 Silica aerogel (A) and, Urethane resin emulsion (B) and, Cellulose nanofiber (C) and Nonionic surfactant (D) and Water and Includes, When the solid content mass of the urethane resin emulsion (B) is B (parts by mass) and the solid content mass of the cellulose nanofiber (C) is C (parts by mass), A paint for insulating materials with a B / C value of 0.5 or higher and 20 or lower. Section 2 The thermal insulation coating according to item 1, wherein the urethane resin emulsion (B) is a carbonate-based urethane resin emulsion. Section 3 The silica aerogel (A) has an average particle size of 1 to 500 μm, as described in item 1 or 2 for thermal insulation coatings. Section 4 A thermal insulation coating containing a cured product of a thermal insulation coating described in any one of items 1 to 3. Section 5 An insulating material containing the insulating coating described in item 4. [Effects of the Invention]

[0010] The thermal insulation coating of the present invention exhibits excellent dispersibility of silica aerogel and good coatability, and can form a thermal insulation coating film with high durability and excellent thermal insulation properties.

[0011] The heat-insulating coating film and the heat-insulating material containing the heat-insulating coating film of the present invention have high durability and excellent heat insulation properties. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described in detail below. In this specification, the expressions "containing" and "including" include the concepts of "containing," "including," "substantially consisting of," and "consisting only of."

[0013] 1. Insulation paint The thermal insulation coating of the present invention comprises silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), nonionic surfactant (D), and water, wherein when the solid content mass of the urethane resin emulsion (B) is B (parts by mass) and the solid content mass of the cellulose nanofiber (C) is C (parts by mass), the B / C value is 0.5 or more and 20 or less.

[0014] The coating material for heat insulation of the present invention has excellent dispersibility of silica aerogel and good coating properties. In addition, the coating material for heat insulation of the present invention can form a heat insulation coating film having high durability and excellent heat insulation properties, so that an excellent heat insulation material can be formed. Therefore, the coating material for heat insulation of the present invention can be suitably used as a raw material for manufacturing a heat insulation material. Hereinafter, each component contained in the coating material for heat insulation of the present invention and the coating material for heat insulation will be described in order.

[0015] (Silica aerogel (A)) The coating material for heat insulation of the present invention contains silica aerogel as an essential component. In this specification, the silica aerogel contained in the coating material for heat insulation is denoted as "silica aerogel (A)".

[0016] The type of silica aerogel (A) is not particularly limited, and for example, known silica aerogels can be widely cited. Generally, silica aerogel is formed by silica fine particles of about several tens of nm forming a network-like fine structure and has a porous structure with fine pores. The size of the silica aerogel (A) used in the present invention is not particularly limited. For example, the diameter of the silica fine particles (primary particles) forming the skeleton of the silica aerogel can be about 2 to 5 nm, and the size of the pores formed between the skeletons can be about 10 to 50 nm.

[0017] The shape of the silica aerogel (A) includes, for example, particulate shapes such as spherical particles and irregularly shaped particles, and块状. When the silica aerogel (A) is formed in a particulate shape, the average particle diameter of the silica aerogel is preferably, for example, 1 μm or more and 500 μm or less. That is, the silica aerogel (A) preferably has an average particle diameter of 1 to 500 μm. In this case, the stability and coating properties of the coating material for heat insulation are likely to be improved, and the durability of the coating film is also likely to be enhanced, so that it is easy to form a heat insulation material having excellent heat insulation performance.

[0018] The average particle diameter of the silica aerogel (A) is more preferably 2 μm or more, still more preferably 5 μm or more, particularly preferably 10 μm or more, and more preferably 300 μm or less, still more preferably 200 μm or less, still more preferably 150 μm or less, and particularly preferably 100 μm or less.

[0019] In the present invention, the average particle diameter of the silica aerogel (A) means a value measured using the laser diffraction method. Specifically, it refers to a value measured using the particle size distribution meter "SALD-2000" manufactured by Shimadzu Corporation for the heat insulating paint of the present invention in which the silica aerogel (A) is dispersed.

[0020] The average particle diameter of the silica aerogel (A) can be adjusted, for example, in Step 1 performed in the method for preparing the heat insulating paint described below. Specifically, the average particle diameter of the silica aerogel (A) can be adjusted according to the stirring conditions performed in Step 1 as described below.

[0021] The specific surface area of the silica aerogel (A) by the BET method is not particularly limited. For example, it is 400 m 2 / g or more and 1000 m 2 / g or less.

[0022] The method for producing the silica aerogel (A) is not particularly limited and can be obtained by drying a wet gel of silica. In this case, examples of the drying method include atmospheric pressure drying or supercritical drying.

[0023] The silica aerogel (A) can be obtained from commercially available products. Examples of commercially available products of the silica aerogel (A) include silica aerogel particles "P-200" manufactured by Cabot Corporation.

[0024] (Urethane resin emulsion (B)) The heat insulating paint of the present invention contains a urethane resin emulsion as an essential component. In this specification, the urethane resin emulsion contained in the heat insulating paint is referred to as "urethane resin emulsion (B)".

[0025] While urethane resin emulsion (B) originally refers to a dispersion of urethane resin in water or the like, in the thermal insulation coating according to the present invention, it is not possible to distinguish between the water or the like contained in the urethane resin emulsion (B) and the water contained in the thermal insulation coating. Therefore, in the thermal insulation coating included in the present invention, urethane resin emulsion (B) refers to the urethane resin particles themselves, and the solvent such as water is not considered. However, as will be described later, when manufacturing the thermal insulation coating according to the present invention, urethane resin particles dispersed in a solvent such as water (polyurethane resin aqueous dispersion) are used to formulate the urethane resin emulsion (B).

[0026] Examples of urethane resins constituting the urethane resin emulsion (B) include reaction products (polyaddition reaction products) of polyols and polyisocyanates. The polyols are compounds having two or more hydroxyl groups in their molecules, and examples include polycarbonate polyols, polyester polyols, polyhydric alcohols, polyether polyols, polyether ester polyols, polyolefin polyols, polyacrylic polyols, polyacetal polyols, polybutadiene polyols, polysiloxane polyols, fluorine polyols, and other compounds having two or more hydroxyl groups at the molecular ends or within the molecule.

[0027] As the polycarbonate polyol, it is preferable to use a polycarbonate diol, and more preferably a polycarbonate diol derived from an aliphatic diol (-ROCOO-, where R represents aliphatic). Specific examples of such aliphatic diols include aliphatic diols having 1 to 10 carbon atoms, such as ethylene glycol, diethylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,3-propylene glycol, 1,2-propylene glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and neopentyl glycol.

[0028] Examples of the polyester polyol include esterified condensates obtained by reacting a low molecular weight polyol, such as the aliphatic diol mentioned above, with a polycarboxylic acid. Examples of polycarboxylic acids include succinic acid, glutaric acid, adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, and tetrahydrofuranic acid. Two or more of these may also be used in combination.

[0029] The aforementioned polyhydric alcohols are not particularly limited and include, for example, ethylene glycol, diethylene glycol, butanediol, propylene glycol, hexanediol, bisphenol A, bisphenol B, bisphenol S, hydrogenated bisphenol A, dibromobisphenol A, 1,4-cyclohexanedimethanol, dihydroxyethyl terephthalate, hydroquinone dihydroxyethyl ether, trimethylolpropane, glycerin, pentaerythritol, and the like.

[0030] Examples of the polyether polyol include alkylene derivatives of polyhydric alcohols, polytetramethylene glycol, and polythioether polyols.

[0031] The polyolefin polyol is not particularly limited, but examples include polybutadiene polyols, polyisoprene polyols, and hydrogenated polyols thereof.

[0032] The polyol is preferably at least one selected from the group consisting of polycarbonate polyols and polyester polyols. In this case, the stability and applicability of the insulation coating are easily improved, and the durability of the coating film is also easily increased, making it easier to form an insulation material with excellent insulation performance. The polyol is particularly preferably polycarbonate polyol.

[0033] Therefore, in the thermal insulation coating of the present invention, the urethane resin emulsion (B) is preferably at least one selected from the group consisting of carbonate-based urethane resin emulsion and ester-based urethane resin emulsion, and is particularly preferably a carbonate-based urethane resin emulsion.

[0034] The polyisocyanate is not particularly limited, and any polyisocyanate commonly used in the art can be used. Specifically, examples include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, and aromatic aliphatic polyisocyanates.

[0035] Examples of aliphatic polyisocyanates include tetramethylene diisocyanate, dodecamethylene diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, and 3-methylpentane-1,5-diisocyanate.

[0036] Examples of alicyclic polyisocyanates include isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, and 1,3-bis(isocyanate methyl)cyclohexane.

[0037] Examples of aromatic polyisocyanates include tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, and 1,4-phenylene diisocyanate.

[0038] Examples of aromatic aliphatic polyisocyanates include dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, and α,α,α,α-tetramethylxylylene diisocyanate. Modified forms such as dimers, trimers, and biuretized isocyanates of these organic polyisocyanates can also be used. These can be used individually or in combination of two or more.

[0039] In the urethane resin emulsion (B), the number-average molecular weight of the urethane resin is, for example, 10,000 or more and 500,000 or less.

[0040] The method for producing the urethane resin emulsion (B) is not particularly limited, and for example, known manufacturing methods can be widely employed. For example, the urethane resin emulsion (B) can be obtained by a manufacturing method utilizing emulsification dispersion.

[0041] One method for producing a polyurethane resin aqueous dispersion using emulsification and dispersion is to prepare a urethane prepolymer by mixing a polyol and a polyisocyanate, and then emulsify and disperse this urethane prepolymer. This allows for the preparation of a polyurethane resin aqueous dispersion containing urethane resin, and enables the production of a urethane resin emulsion (B) contained in a paint for heat insulation materials. This mixing process can be carried out in a solvent. The solvent is preferably inert to the isocyanate group and capable of dissolving the resulting urethane prepolymer. Examples of solvents include dioxane, methyl ethyl ketone, dimethylformamide, tetrahydrofuran, N-methyl-2-pyrrolidone, acetone, toluene, ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate.

[0042] The above mixing process allows the reaction between the polyol and polyisocyanate to proceed, producing a urethane prepolymer. After the urethane prepolymer is produced, the emulsification and dispersion described above is carried out. Before emulsification and dispersion, neutralization treatment can be performed with a neutralizing agent as needed. Examples of neutralizing agents include non-volatile bases such as sodium hydroxide and potassium hydroxide, tertiary amines such as trimethylamine, triethylamine, dimethylethanolamine, methyldiethanolamine, and triethanolamine, and volatile bases such as ammonia.

[0043] The blocking agent can be added to the urethane prepolymer solution before or after the neutralization treatment, preferably simultaneously with the neutralization treatment. The blocking agent reacts with the remaining NCO groups and stops the reaction. This makes it easier to adjust the molecular weight of the urethane resin. A wide range of known blocking agents can be used, for example, compounds having a monofunctional active hydrogen group, specifically monohydric alcohol compounds and monohydric amino compounds (e.g., dibutylamine).

[0044] The method of emulsification and dispersion is not particularly limited, and a wide range of known methods can be employed. For example, the urethane prepolymer can be emulsified and dispersed by mixing a solution of the urethane prepolymer with an aqueous solvent and applying shear using an emulsification and dispersion machine such as a homogenizer. The aqueous solvent may contain the neutralizing agent as needed.

[0045] Chain extension can be performed by adding a chain extender simultaneously with or after the emulsification and dispersion. This generates urea bonds through an interfacial polymerization reaction between the isocyanate groups in the emulsified micelles and the chain extender, thereby improving the crosslinking density within the emulsified micelles and forming a three-dimensional crosslinked structure. Examples of chain extenders include diamine compounds and polyamine compounds. Examples of diamine compounds include ethylenediamine, trimethylenediamine, piperazine, isophoronediamine, diethylenetriamine, dipropylenetriamine, and amino group-containing silane coupling agents, while examples of polyamine compounds include diethylenetriamine, dipropylenetriamine, and triethylenetetramine. Other polyamines may include polycarbodiimide compounds, for example, Nisshinbo Chemical's crosslinking agent for carbodilite aqueous resins.

[0046] The urethane resin emulsion (B) can also be obtained from commercially available products; for example, it can be obtained from the Superflex® series of Daiichi Kogyo Seiyaku Co., Ltd.

[0047] (Cellulose nanofiber(C)) The thermal insulation coating of the present invention contains cellulose nanofibers as an essential component. In this specification, cellulose nanofibers contained in the thermal insulation coating are referred to as "cellulose nanofibers (C)".

[0048] As the cellulose nanofiber (C), those that satisfy the following (a) to (c) can be used. (a) The number-average fiber diameter is between 3 nm and 100 nm. (b) Having a cellulose type I crystalline structure. (c) The average aspect ratio must be between 2 and 5000.

[0049] The number-average fiber diameter in (a) above is more preferably 50 nm or less, even more preferably 30 nm or less, and may be 10 nm or less. The number-average fiber diameter can be measured as follows: an aqueous dispersion of cellulose nanofibers with a solid content of 0.05 to 0.1 mass% is prepared, and this aqueous dispersion is cast onto a hydrophilically treated carbon film coated grid to be used as a sample for observation with a transmission electron microscope (TEM). If the sample contains fibers with a large fiber diameter, a scanning electron microscope (SEM) image of the surface cast on glass may be observed. The observation sample may also be negatively stained with, for example, 2 mass% uranyl acetate. Then, observation of the electron microscope image is performed at a magnification of 5000x, 10000x, or 50000x depending on the size of the constituent fibers. At that time, an axis of arbitrary image width is assumed in the obtained image, and the sample and observation conditions (magnification, etc.) are adjusted so that 20 or more fibers intersect with that axis. After obtaining observation images that satisfy these conditions, two random axes are drawn vertically and horizontally for each image, and the fiber diameters of the fibers intersecting the axes are visually read. In this way, at least three non-overlapping surface images are taken with an electron microscope, and the fiber diameter values ​​of the fibers intersecting the two axes in each image are read (therefore, information on the fiber diameters of at least 20 × 2 × 3 = 120 fibers is obtained). The arithmetic mean of the fiber diameters obtained in this way is defined as the number-mean fiber diameter.

[0050] The presence of the cellulose type I crystal structure described in (b) above can be identified by the fact that the diffraction profile obtained by wide-angle X-ray diffraction measurement shows typical peaks at two positions: around 2θ = 14° to 17° and around 2θ = 22° to 23°.

[0051] The average aspect ratio in (c) above is more preferably 50 or more, even more preferably 100 or more, and may be 200 or more. The average aspect ratio is more preferably 1000 or less, and may be 500 or less. The average aspect ratio can be measured as follows: That is, the number-average fiber diameter is calculated according to the method described above. The number-average fiber length of cellulose nanofibers is also calculated from similar observation images. Specifically, the length from the start point to the end point of at least 10 fibers (fiber length) is read visually. For branched fibers, the length of the longest part of the fiber is taken as the fiber length. The arithmetic mean of the fiber lengths obtained in this way is calculated and taken as the number-average fiber length. The average aspect ratio is calculated using these values ​​according to the following formula. Average aspect ratio = Number-average fiber length (nm) / Number-average fiber diameter (nm)

[0052] Cellulose nanofibers (C) may have anionic functional groups. Examples of anionic functional groups include at least one selected from the group consisting of carboxyl groups, phosphate groups, sulfonic acid groups, nitrate groups, boric acid groups, and sulfate groups. In this specification, the carboxyl group is a concept that includes not only the acidic form (-COOH) but also the salt form, i.e., a carboxylic acid base (-COOX, where X is a cation that forms a salt with a carboxylic acid), and acidic and salt forms may be present together. Similarly, the phosphate group, sulfonic acid group, nitrate group, boric acid group, and sulfate group are also concepts that include not only the acidic form but also the salt form, and acidic and salt forms may be present together. Examples of salts are not particularly limited and include alkali metal salts such as sodium salts and potassium salts, alkaline earth metal salts such as magnesium salts and calcium salts, onium salts such as ammonium salts and phosphonium salts, and amine salts such as primary amines, secondary amines, and tertiary amines.

[0053] The amount of anionic functional groups in cellulose nanofibers (C) is, for example, 0.5 to 3.0 mmol / g per dry mass of cellulose nanofibers (C). The amount of anionic functional groups can be measured, for example, when the anionic functional group is a carboxyl group, using a cellulose nanofiber-containing slurry prepared to a concentration of 0.1 to 1% by mass. Specifically, 60 mL of the slurry is prepared, the pH is adjusted to approximately 2.5 with a 0.1 mol / L hydrochloric acid aqueous solution, and then a 0.05 mol / L sodium hydroxide aqueous solution is added dropwise. Electrical conductivity is measured and this process is continued until the pH reaches approximately 11. The amount of sodium hydroxide consumed during the neutralization stage of the weak acid, where the change in electrical conductivity is gradual, is calculated using the following formula: Anionic functional group content (mmol / g) = V (mL) × [0.05 / Mass of cellulose nanofiber (g)] This can be determined accordingly. The phosphate group can also be measured using a similar electrical conductivity measurement method. Other anionic groups can be measured using known methods.

[0054] The cellulose nanofiber (C) preferably has a carboxyl group as an anionic functional group. Examples include oxidized cellulose nanofibers obtained by oxidizing the hydroxyl group of the glucose unit in the cellulose molecule, and carboxymethylated cellulose nanofibers obtained by carboxymethylating the hydroxyl group of the glucose unit in the cellulose molecule.

[0055] Oxidized cellulose nanofibers include those obtained by selectively oxidizing the hydroxyl group at the C6 position of the glucose unit in the cellulose molecule to a carboxyl group. These oxidized cellulose nanofibers are obtained by oxidizing natural cellulose, such as wood pulp, in the presence of an N-oxyl compound using a co-oxidant, followed by defibration (micronization) treatment. As the N-oxyl compound, compounds having a nitroxyl radical, which are generally used as oxidation catalysts, are used, for example, piperidine nitroxyoxyl radicals, and 2,2,6,6-tetramethylpiperidinooxyl radical (TEMPO) or 4-acetamide-TEMPO are particularly preferred. Cellulose nanofibers oxidized with TEMPO are generally called TEMPO-oxidized cellulose nanofibers (TOCN). Note that oxidized cellulose nanofibers may also have an aldehyde group or a ketone group in addition to the carboxyl group.

[0056] Cellulose nanofibers (C) can be obtained, for example, by known manufacturing methods, or they can be obtained from commercially available products. An example of commercially available cellulose nanofibers (C) is the "Leocrysta" (registered trademark) series manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0057] (Nonionic surfactant (D)) The thermal insulation coating of the present invention contains a nonionic surfactant as an essential component. In this specification, the nonionic surfactant contained in the thermal insulation coating is denoted as "nonionic surfactant (D)".

[0058] If the thermal insulation coating of the present invention does not contain a nonionic surfactant (D), the dispersibility of the silica aerogel (A) decreases, the coatability is impaired, and the durability of the coating film decreases, making it impossible to obtain the desired thermal insulation performance.

[0059] The type of nonionic surfactant (D) is not particularly limited; for example, known nonionic surfactants can be widely used in the present invention.

[0060] Examples of nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, sucrose fatty acid esters, and fatty acid alkanolamides.

[0061] More specific examples of nonionic surfactants include polyoxyalkylene alkyl ethers, in which case the most preferred is a polyoxyalkylene alkyl ether in which the main alkyl group has 20 or fewer carbon atoms (more preferably 8 to 16 carbon atoms, and even more preferably 8 to 12 carbon atoms). Examples include polyoxyalkylene lauryl ethers such as polyoxyethylene lauryl ether and polyoxyethylene polyoxypropylene lauryl ether; polyoxyalkylene isodecyl ethers such as polyoxyethylene isodecyl ether and polyoxyethylene polyoxypropylene isodecyl ether; polyoxyalkylene branched decyl ethers such as polyoxyethylene branched decyl ether and polyoxyethylene polyoxypropylene branched decyl ether; polyoxyalkylene block polymers such as polyoxyethylene polyoxypropylene block polymer; and polyoxyalkylene styrene phenyl ethers such as polyoxyethylene styrene phenyl ether. Any one or two or more of these can be used. Here, "the main alkyl group has 20 or fewer carbon atoms" means that 60 mol% or more of the alkyl group has 20 or fewer carbon atoms. Furthermore, the number of carbon atoms in "oxyalkylene" is preferably 2 to 4, and it is preferable that it contains at least an oxyethylene group.

[0062] Nonionic surfactants (D) can be obtained, for example, by known manufacturing methods, or they can be obtained from commercially available products. Examples of commercially available nonionic surfactants (D) include the "Neugen" (registered trademark) series manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0063] (Insulating paint) The thermal insulation coating of the present invention contains silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), nonionic surfactant (D), and water as essential components. The thermal insulation coating of the present invention may also contain other components as long as the effects of the present invention are not hindered. Examples of other components include pH adjusters, thickeners, light stabilizers, antioxidants, preservatives, flame retardants, pigments, colorants, fungicides, and lubricants. One or more of these additives may be included in the thermal insulation coating.

[0064] In the thermal insulation coating of the present invention, when the solid content mass of the urethane resin emulsion (B) contained in the thermal insulation coating is B (parts by mass) and the solid content mass of the cellulose nanofiber (C) contained in the thermal insulation coating is C (parts by mass), the B / C value is 0.5 or more and 20 or less, as described above. As a result, the thermal insulation coating of the present invention has excellent dispersibility of silica aerogel and good coatability, and can form a thermal insulation coating film with high durability and excellent thermal insulation properties.

[0065] If the B / C value described above is less than 0.5, the durability of the coating obtained from the thermal insulation coating of the present invention will decrease, and it will not be able to achieve the desired thermal insulation performance. Furthermore, if the B / C value exceeds 20, the dispersibility of silica aerogel (A) in the thermal insulation coating of the present invention will decrease, the coatability will be impaired, and the durability of the coating will also decrease, so the desired thermal insulation performance cannot be obtained.

[0066] The B / C value mentioned above is preferably 1 or greater, more preferably 3 or greater, even more preferably 4.5 or greater, particularly preferably 4.8 or greater, and also preferably 19 or less, more preferably 18 or less, even more preferably 16 or less, and particularly preferably 15 or less.

[0067] Here, the total mass of the silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), nonionic surfactant (D), and water contained in the thermal insulation coating of the present invention is denoted as "total mass M".

[0068] The solid content of the urethane resin emulsion (B) per 100 parts by mass of total mass M is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, even more preferably 0.5 parts by mass or more, particularly preferably 1 part by mass or more, and also preferably 10 parts by mass or less, more preferably 8 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less.

[0069] The solid content mass of cellulose nanofibers (C) per 100 parts by mass of total mass M is preferably 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, even more preferably 0.05 parts by mass or more, particularly preferably 0.1 parts by mass or more, and also preferably 3 parts by mass or less, more preferably 1 part by mass or less, even more preferably 0.8 parts by mass or less, and particularly preferably 0.5 parts by mass or less.

[0070] The solid content of silica aerogel (A) per 100 parts by mass of total mass M is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, particularly preferably 2 parts by mass or more, and also preferably 20 parts by mass or less, more preferably 15 parts by mass or less, even more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less.

[0071] The solid content of the nonionic surfactant (D) per 100 parts by mass of the total mass M is preferably 0.01 parts by mass or more, more preferably 0.05 parts by mass or more, even more preferably 0.1 parts by mass or more, particularly preferably 0.2 parts by mass or more, and also preferably 5 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, and particularly preferably 1 part by mass or less.

[0072] The thermal insulation coating of the present invention preferably has a solid content concentration of 0.5% by mass or more, more preferably 1% by mass or more, even more preferably 2% by mass or more, particularly preferably 3% by mass or more, and also preferably 30% by mass or less, more preferably 20% by mass or less, even more preferably 15% by mass or less, and particularly preferably 10% by mass or less.

[0073] In the thermal insulation coating of the present invention, the total mass of silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), nonionic surfactant (D), and water is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more, based on the total mass of the thermal insulation coating. The thermal insulation coating of the present invention may also consist only of silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), nonionic surfactant (D), and water.

[0074] The thermal insulation coating of the present invention contains silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), and nonionic surfactant (D), and therefore exhibits excellent dispersibility of silica aerogel and good coatability. In particular, the thermal insulation coating of the present invention can be easily applied to a substrate without dripping, and a coating film in which each component is uniformly dispersed can be formed, thereby exhibiting excellent thermal insulation performance.

[0075] Furthermore, the thermal insulation coating of the present invention can form a thermal insulation coating film with high durability and excellent thermal insulation properties, thereby forming an excellent thermal insulation material. In particular, since the silica aerogel (A) is less likely to detach from the thermal insulation coating film, it is possible to maintain excellent thermal insulation performance over a longer period of time.

[0076] Therefore, the thermal insulation coating of the present invention can be suitably used as a raw material for manufacturing thermal insulation materials.

[0077] (Method for preparing paint for thermal insulation) The method for preparing the thermal insulation coating of the present invention is not particularly limited, and for example, known methods can be widely employed. For example, the thermal insulation coating of the present invention can be prepared by mixing predetermined raw materials in predetermined proportions. Preferably, the thermal insulation coating of the present invention can be prepared by a manufacturing method comprising: step 1, mixing predetermined amounts of silica aerogel (A), cellulose nanofiber (C), nonionic surfactant (D), and water to prepare a dispersion of silica aerogel (A); and step 2, mixing the dispersion of silica aerogel (A) obtained in step 1 with the urethane resin emulsion (B) to obtain a thermal insulation coating.

[0078] Step 1 is a step for preparing a dispersion of silica aerogel (A). Such a dispersion can be prepared by mixing silica aerogel (A), cellulose nanofiber (C), nonionic surfactant (D), and water in predetermined proportions to prepare a mixture, and then stirring this mixture. The method for preparing the mixture is not particularly limited, and for example, known mixing methods can be widely employed.

[0079] When preparing the mixture, the mixing ratio of silica aerogel (A), cellulose nanofiber (C), nonionic surfactant (D), and water can be adjusted within an appropriate range, for example, depending on the amount of each component and the solid content concentration contained in the desired thermal insulation coating.

[0080] The method of stirring the mixture is not particularly limited, and for example, known stirring means can be widely employed. Specifically, a dispersion of silica aerogel (A) can be obtained by stirring the mixture while applying shear to it using an emulsification and dispersion device such as a homomixer or homogenizer. In this case, the average particle size of silica aerogel (A) can be controlled according to the magnitude of the shear applied to the mixture. An example of an emulsification and dispersion device is the PRIMIX homomixer "Laborution".

[0081] When obtaining a dispersion of silica aerogel (A) using an emulsification and dispersion device, the average particle size of the silica aerogel (A) can be controlled, for example, by adjusting the stirring speed. The stirring speed of the emulsification and dispersion device can be 1,000 rpm to 30,000 rpm, preferably 2,000 rpm to 20,000 rpm, more preferably 3,000 rpm to 10,000 rpm, and particularly preferably 4,000 to 9,000 rpm. By using these stirring speeds, it becomes easier to obtain a dispersion of silica aerogel (A) with an average particle size of 1 μm or more and 500 μm or less. The stirring time using the emulsification and dispersion device is not particularly limited and can be set within an appropriate range depending on the stirring speed, for example, 30 to 180 minutes.

[0082] In step 2, the silica aerogel (A) dispersion obtained in step 1 is mixed with a urethane resin emulsion (B). This mixing yields the thermal insulation coating of the present invention.

[0083] As the urethane resin emulsion (B) used in step 2, the aforementioned polyurethane resin aqueous dispersion, that is, a dispersion in which urethane resin is dispersed in an aqueous solvent, can be used. Therefore, in step 2, the silica aerogel (A) dispersion and the polyurethane resin aqueous dispersion are mixed. Examples of aqueous solvents contained in the polyurethane resin aqueous dispersion include water, lower alcohols having about 1 to 3 carbon atoms, and mixed solvents thereof, with water being preferred.

[0084] Polyurethane resin aqueous dispersions can be obtained, for example, by the emulsification dispersion method described above, or they can be obtained from commercially available products. Examples of commercially available polyurethane resin aqueous dispersions include the Superflex® series from Daiichi Kogyo Seiyaku Co., Ltd.

[0085] The solid content concentration of the polyurethane resin aqueous dispersion is, for example, 20 to 50% by mass, preferably 30 to 45% by mass.

[0086] In step 2, the method for mixing the silica aerogel (A) dispersion and the polyurethane resin aqueous dispersion is not particularly limited, and for example, known mixing methods can be widely employed. For example, as in step 1, the silica aerogel (A) dispersion and the polyurethane resin aqueous dispersion can be mixed using an emulsification and dispersion device such as a homomixer or homogenizer.

[0087] When mixing a dispersion of silica aerogel (A) and an aqueous dispersion of polyurethane resin using an emulsifying and dispersing device, the stirring speed can be, for example, 1,000 rpm to 20,000 rpm, preferably 2,000 rpm to 10,000 rpm. The stirring time is not particularly limited and can be set within an appropriate range depending on the stirring speed, for example, 0.1 to 30 minutes.

[0088] By following steps 1 and 2 described above, the thermal insulation coating of the present invention can be obtained. The method for manufacturing the thermal insulation coating of the present invention may include other steps in addition to steps 1 and 2, or it may consist only of steps 1 and 2. Furthermore, the thermal insulation coating of the present invention can also be prepared by a manufacturing method other than the method including steps 1 and 2.

[0089] 2. Thermal insulation coatings and thermal insulation materials An insulating coating can be formed using the insulating coating of the present invention. For example, a cured product of the insulating coating can be formed on the surface of a substrate using the insulating coating of the present invention, and such cured product can be used as an insulating coating. Furthermore, the insulating coating formed on the substrate can be used as an insulating material.

[0090] Because the aforementioned heat-insulating coating contains the cured product of the heat-insulating paint of the present invention, it has high durability and excellent heat insulation performance. In particular, since the silica aerogel (A) is less likely to fall off from the heat-insulating coating, the heat-insulating coating can maintain its excellent heat insulation performance for a longer period of time.

[0091] Since the heat insulating coating is made of a cured product of the heat insulating paint of the present invention, it can be obtained, for example, by curing the heat insulating paint of the present invention. Specifically, the heat insulating coating can be obtained by applying the heat insulating paint of the present invention to a substrate to form a coating on the substrate surface, and then curing the coating to form a cured product. Alternatively, the heat insulating coating can also be formed on the substrate surface by immersing the substrate in the heat insulating paint of the present invention. In this case as well, a cured product of the heat insulating paint of the present invention is formed on the substrate surface.

[0092] Examples of substrates include fibrous materials such as cloth, nonwoven fabric, woven fabric, and other fabrics; films and substrates formed from resin, etc.; inorganic plates; metal plates; and the like. The substrate may also be a porous material.

[0093] The method of applying the thermal insulation coating of the present invention to a substrate to form a coating film is not particularly limited. For example, known coating means such as applicators, bar coaters, die coaters, comma coaters (registered trademark), and roll coaters can be used, or the thermal insulation coating of the present invention can be applied to the substrate by methods such as spray application. In particular, since the thermal insulation coating of the present invention contains the above-mentioned predetermined components in predetermined proportions, it has excellent dispersion stability and coating properties for silica aerogel (A), so it can be easily applied to a substrate and a coating film in which each component is uniformly dispersed can be formed.

[0094] The coating film formed on the substrate undergoes a drying treatment, during which volatile components such as water dry out, transforming it into a cured product. This cured product contains solid components of silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), and nonionic surfactant (D). The drying treatment can be carried out at, for example, 50 to 150°C, preferably 70 to 120°C.

[0095] As described above, a cured product of the insulating coating can be obtained as an insulating coating film. The content ratio of silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), and nonionic surfactant (D) contained in the insulating coating film can be considered to be the same as the content ratio of silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), and nonionic surfactant (D) contained in the insulating coating film of the present invention. Therefore, in the insulating coating film as well, the B / C value mentioned above is 0.5 or more and 20 or less.

[0096] The thermal insulation material of the present invention can be formed using the thermal insulation coating. Therefore, the thermal insulation material of the present invention may include, for example, the base material and the thermal insulation coating. The thermal insulation material of the present invention may consist only of the thermal insulation coating, or it may consist only of the base material and the thermal insulation coating, or it may be a combination of the base material and the thermal insulation coating with other components.

[0097] The thermal insulation material of the present invention includes a multi-layer thermal insulation coating formed from the thermal insulation coating of the present invention, and therefore has high durability and excellent thermal insulation performance.

[0098] In identifying the inventions contained herein, the components (properties, structures, functions, etc.) described in each embodiment of this disclosure may be combined in any way. That is, this disclosure encompasses all subject matter consisting of any combination of the combinatable components described herein. [Examples]

[0099] The present invention will be described more specifically below with reference to examples, but the present invention is not limited to the embodiments of these examples.

[0100] (Example 1) A thermal insulation coating containing silica aerogel (A), urethane resin emulsion (B), cellulose nanofiber (C), nonionic surfactant (D), and water was prepared according to the formulation conditions of Example 1 shown in Table 1. Specifically, the thermal insulation coating was prepared using the following procedure. First, 5.0 parts by mass of "P-200" silica aerogel particles manufactured by Cabot Corporation were used as silica aerogel (A) in terms of solid content; 0.4 parts by mass of "Reocrysta I-2SX" TEMPO oxidized cellulose nanofibers manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (solid content concentration 2% by mass, number average fiber diameter 3 nm) were used as cellulose nanofiber (C) in terms of solid content; 0.5 parts by mass of "Neugen LF-60X" nonionic surfactant manufactured by Daiichi Kogyo Seiyaku Co., Ltd. (polyoxyalkylene alkyl ether) were used as nonionic surfactant (D) in terms of solid content; and water (pure water) was mixed to prepare a mixture. This mixture was stirred at 8000 rpm for 120 minutes using a homomixer (Laborution, manufactured by PRIMIX) to prepare a dispersion of silica aerogel (A) (Step 1).

[0101] Next, the entire amount of the silica aerogel (A) dispersion obtained in step 1 was mixed with 0.2 parts by mass of "Superflex 460" (solid content concentration 38% by mass), a carbonate-based polyurethane resin aqueous dispersion from Daiichi Kogyo Seiyaku Co., Ltd., as the urethane resin emulsion (B). The mixture was stirred in a homomixer at 5000 rpm for 5 minutes and then degassed to obtain a thermal insulation coating with a solid content concentration of 6.1% by mass (step 2). Note that the amount of water shown in Table 1 represents the total amount of water contained in the silica aerogel (A) dispersion and the polyurethane resin aqueous dispersion (the same applies to Table 2 below).

[0102] (Example 2) As shown in Table 1, a thermal insulation coating with a solid content concentration of 7.8% by mass was obtained using the same method as in Example 1, except that the amount of urethane resin emulsion (B) used was changed to 1.9 parts by mass in terms of solid content.

[0103] (Example 3) As shown in Table 1, a thermal insulation coating with a solid content concentration of 7.6% by mass was obtained using the same method as in Example 2, except that the amount of cellulose nanofiber (C) used was changed to 0.2 parts by mass in terms of solid content.

[0104] (Example 4) As shown in Table 1, a thermal insulation coating with a solid content concentration of 7.5% by mass was obtained using the same method as in Example 2, except that the amount of cellulose nanofiber (C) used was changed to 0.1 parts by mass in terms of solid content.

[0105] (Example 5) As shown in Table 1, a thermal insulation coating with a solid content concentration of 3.5% by mass was obtained using the same method as in Example 4, except that the amount of silica aerogel (A) used was changed to 1.0 part by mass in terms of solid content.

[0106] (Example 6) An insulating coating with a solid content of 7.8% by mass was obtained using the same method as in Example 2, except that the urethane resin emulsion (B) was replaced with 1.8 parts by mass of "Superflex 210" (solid content concentration 35% by mass), an ester-based polyurethane resin aqueous dispersion from Daiichi Kogyo Seiyaku Co., Ltd.

[0107] (Example 7) An insulating coating with a solid content of 7.8% by mass was obtained using the same method as in Example 2, except that the nonionic surfactant (D) was changed to "Neugen EA-167" (polyoxyethylene styrene-phenyl ether), a nonionic surfactant from Daiichi Kogyo Seiyaku Co., Ltd.

[0108] (Example 8) To 2 g of coniferous pulp, 150 ml of water, 0.25 g of sodium bromide, and 0.025 g of TEMPO were added and thoroughly stirred to disperse the mixture. Then, a 13 wt% sodium hypochlorite aqueous solution (co-oxidant) was added so that the amount of sodium hypochlorite was 10 mmol / g per 1.0 g of pulp, and the reaction was started. As the reaction progressed, the pH decreased, so a 0.5 N sodium hydroxide aqueous solution was added dropwise to maintain the pH at 10-11, and the reaction was continued until no further change in pH was observed (reaction time: 120 minutes). After the reaction was complete, 0.1 N hydrochloric acid was added to neutralize the mixture, and then the mixture was purified by repeated filtration and washing with water to prepare cellulose fibers with oxidized fiber surfaces. This was adjusted to a solid content concentration of 2.0% by mass, and a 24% sodium hydroxide aqueous solution was added to adjust the pH to 7.0. Then, it was treated in a single pass at 50 MPa using a high-pressure disperser (Microfluidizer M-110, Microfluidics Co., Ltd.) to prepare cellulose nanofibers (number-average fiber diameter 20 nm). Except for using these cellulose nanofibers as cellulose nanofibers (C), a thermal insulation coating with a solid content concentration of 7.8% by mass was obtained by the same method as in Example 2.

[0109] (Example 9) As shown in Table 1, a thermal insulation coating with a solid content of 7.8% by mass was obtained in the same manner as in Example 2, except that in step 1, the mixed liquid was stirred in a homomixer at 3000 rpm for 60 minutes to prepare a dispersion of silica aerogel (A).

[0110] (Example 10) As shown in Table 1, a thermal insulation coating with a solid content of 7.8% by mass was obtained in the same manner as in Example 2, except that in step 1, the mixed liquid was stirred in a homomixer at 10,000 rpm for 180 minutes to prepare a dispersion of silica aerogel (A).

[0111] (Comparative Example 1) As shown in Table 2, a thermal insulation coating with a solid content concentration of 6.0% by mass was obtained using the same method as in Example 1, except that the amount of urethane resin emulsion (B) used was changed to 0.1 parts by mass in terms of solid content.

[0112] (Comparative Example 2) As shown in Table 2, a thermal insulation coating with a solid content concentration of 7.5% by mass was obtained using the same method as in Example 2, except that the amount of cellulose nanofiber (C) used was changed to 0.08 parts by mass in terms of solid content.

[0113] (Comparative Example 3) As shown in Table 2, a thermal insulation coating with a solid content of 7.1% by mass was obtained in the same manner as in Example 2, except that the amount of cellulose nanofiber (C) used was changed to 0.2 parts by mass in terms of solid content, and nonionic surfactant (D) was not used.

[0114] (Evaluation method) [Average particle size of silica aerogel] Using a particle size analyzer (SALD-2000, manufactured by Shimadzu Corporation), the average particle size of the thermal insulation coatings obtained in each example and comparative example was measured, and the obtained value was defined as the average particle size of silica aerogel (A).

[0115] [Stability (dispersion stability)] 100g of the thermal insulation coating obtained in each example and comparative example was transferred to a sample bottle and stored at 50°C for one month. After storage, the thermal insulation coating was visually inspected, and its stability (dispersion stability) was evaluated according to the following criteria. ≪Judgment criteria≫ 5: No separation or syneresis of the silica aerogel was observed, indicating excellent stability. 4: Although a slight concentration gradient of silica aerogel was observed, the stability was good. 3: The silica aerogel floated to the surface, and a layer with less than 30% silica aerogel was observed at the bottom, indicating that stability was not necessarily good. 2: The silica aerogel floated to the surface, and a layer lacking 30% to less than 60% silica aerogel was observed at the bottom, indicating poor stability. 1: The silica aerogel completely floated to the surface, and a layer lacking more than 60% silica aerogel was observed at the bottom, indicating extremely poor stability.

[0116] [Coating properties] 50g of the prepared thermal insulation coating obtained in each example and comparative example was applied to polyester fabric (film thickness 1mm) using an applicator (coating film thickness 0.5mm), and the formed coating film was visually observed and the coating properties were evaluated according to the following criteria. ≪Judgment criteria≫ 3: The coating liquid did not drip or soak into the fabric, resulting in a uniform coating film and extremely good coating properties. 2: Although there was some dripping or soaking of the coating liquid into the fabric, a generally uniform coating film was obtained, and the coating properties were good. 1: A uniform coating could not be obtained due to dripping of the coating solution or soaking into the fabric.

[0117] [Durability] The thermal insulation coatings obtained in each example and comparative example were applied to a polyester fabric substrate (10 cm long, 5 cm wide, 1 mm thick) using an applicator to form a coating film with a thickness of 0.5 mm. The coating film was dried for 1 hour in an atmosphere of 100°C to harden it and obtain a cured product. This cured product was used as the thermal insulation coating, and the substrate equipped with this thermal insulation coating was used as an evaluation sample for thermal insulation. The ends of the obtained sample were clipped together, and the longitudinal ends were stretched by 5 mm by hand, held for 3 seconds, and then released. After repeating this 10 times, the state of the thermal insulation coating formed on the evaluation sample was visually observed, and the coating properties were evaluated according to the following criteria. ≪Judgment criteria≫ 4. No cracking of the heat-insulating coating or detachment of the silica aerogel was observed, indicating extremely excellent durability. 3: Almost no cracking of the heat-insulating coating or shedding of the silica aerogel was observed, indicating excellent durability. 2: Although no detachment of the silica aerogel was observed, cracks were found in the heat-insulating coating, but the durability was acceptable for practical use. 1: Both cracking of the heat-insulating coating and detachment of the silica aerogel were observed, indicating extremely poor durability.

[0118] [Thermal insulation performance] Using the evaluation samples of the insulation material prepared in the aforementioned durability evaluation, the thermal conductivity (W / (m·K)) of the insulating coating formed on the samples was measured to evaluate the insulation performance. The thermal conductivity was measured in accordance with ASTM D7984 using a thermal conductivity meter (TCi, manufactured by C-Therm Technologies).

[0119] (Evaluation results) Tables 1 and 2 show the formulation conditions for preparing the thermal insulation coatings prepared in each example (Table 1) and comparative example (Table 2), as well as the B / C value (solid content mass ratio of urethane resin emulsion (B) to cellulose nanofiber (C)) and the average particle size of silica aerogel (A) for each thermal insulation coating. Table 1 also shows the evaluation results of the thermal insulation coatings obtained in each example and comparative example, as well as the evaluation results of the thermal insulation coatings formed from these coatings.

[0120] As can be seen from Table 1, the thermal insulation coatings obtained in the examples exhibited excellent dispersibility of silica aerogel and good coatability. Furthermore, the thermal insulation coatings obtained in the examples were capable of forming a thermal insulation coating with high durability and excellent thermal insulation properties. On the other hand, the thermal insulation coating obtained in Comparative Example 1 had a B / C value of less than 0.5, resulting in poor coatability and durability. The thermal insulation coating obtained in Comparative Example 2 had a B / C value exceeding 20, resulting in poor stability (dispersion stability), coatability, and durability. In addition, the thermal insulation coating obtained in Comparative Example 3 did not contain a nonionic surfactant, resulting in poor dispersion stability and coatability, making it impossible to measure the average particle size of silica aerogel (A), and failing to form the desired thermal insulation coating.

[0121] [Table 1]

[0122] [Table 2]

Claims

1. Silica aerogel (A) and, Urethane resin emulsion (B) and Cellulose nanofiber (C) and Nonionic surfactant (D) and Water and Includes, When the solid content mass of the urethane resin emulsion (B) is B (parts by mass) and the solid content mass of the cellulose nanofiber (C) is C (parts by mass), A paint for insulating materials with a B / C value of 0.5 or higher and 20 or lower.

2. The thermal insulation coating according to claim 1, wherein the urethane resin emulsion (B) is a carbonate-based urethane resin emulsion.

3. The aforementioned silica aerogel (A) has an average particle size of 1 to 500 μm, as described in claim 1, for use as a thermal insulation coating.

4. A heat insulating coating film containing a cured product of a heat insulating coating according to any one of claims 1 to 3.

5. A thermal insulation material containing the thermal insulation coating described in claim 4.

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