Water-based coating composition and building

Abstract

A water-based coating composition capable of forming a coating film with excellent heat insulating properties and non-flammability, and a method for coating buildings using the same. The present invention provides a water-based coating composition containing (A) a water-dispersible resin, (B) hollow particles, and (C) water, wherein the thermal conductivity of a coating film formed from the water-based coating composition is 0.2 W / m K or less, and the total heat generation rate of a 1 mm coating film formed on an aluminum plate measuring 99±1.0 mm x 99±1.0 mm x 0.8 mm for 20 minutes using a cone calorimeter is 8.0 MJ / m 2 A water-based coating composition characterized by:

Description

[Technical Field]

[0001] The present invention relates to a water-based coating composition capable of forming a coating film having excellent heat insulating properties and non-flammability, and a method for coating buildings using the same. [Background technology]

[0002] BACKGROUND ART Conventionally, various coating compositions have been investigated for the purpose of imparting thermal insulation properties, durability, etc. to the exterior surfaces of buildings. For example, there is a coating type heat insulating material that contains aluminosilicate sodium glass, a pigment, a resin emulsion, a dispersant, and an adhesive, in which the aluminosilicate sodium glass has a hollow bead structure, a particle size of 10 to 50 μm, and a content of 10 to 20% by weight, which is known to provide excellent heat insulating properties (Patent Document 1).

[0003] Another example is a matte heat-insulating coating composition that contains porous particles containing titanium white and a resin, and the resin, wherein the titanium white is in the range of 2.0 to 45.0 mass% based on the solid mass of the porous particles, and the porous particles are in the range of 5 to 30 mass% based on the mass of the resin. It is known that this composition can form a coating film for building exterior walls that has excellent finish, base hiding ability, heat insulation, and heat insulation properties (Patent Document 2).

[0004] Another example is a rooftop waterproofing and thermal insulation protection method that includes: Step 1: applying a two-component curing epoxy resin primer coat containing a resin emulsion obtained by water-dispersing a resin with a Tg of 30°C or less to the surface of a rooftop waterproofing material; Step 2: applying a paint containing the resin emulsion obtained by water-dispersing a resin with a Tg of 30°C or less and a pigment to form a waterproof coating layer on the layer obtained in Step 1; and Step 3: applying a heat-shielding topcoat paint on the layer obtained in Step 1, the heat-shielding topcoat paint containing 50% by mass or more of white pigment among the pigment components contained in the composition, the specific gravity of the coating film being 1.0 or more, and the solar reflectance of the formed coating film being 50% or more, to form a heat-shielding coating layer, wherein the total pigment volume concentration for forming the heat-shielding coating layer is lower than the total pigment volume concentration of the paint for forming the waterproof coating layer. It is known that this method achieves excellent finished appearance of the multilayer coating film while maintaining performance such as insulation and waterproofing, and the heat-shielding coating layer can suppress deterioration due to sunlight (Patent Document 3).

[0005] Another example is a coating composition that contains an emulsion resin and a hollow filler, wherein the emulsion resin has a Tg of 10 to 50°C, the hollow filler is an organic balloon and has an average particle size of less than 150 μm, and the tensile strength at 50°C and the electrical conductivity of the coating film are specified, and it is known that this can provide a coating film that has heat insulation properties and can suppress thermal swelling (Patent Document 4).

[0006] Another example is a heat insulating layer forming composition that contains a binder resin, 30% by volume or more and 75% by volume or less of hollow particles, and water, with the water content being 30% by volume or less, and it is known that this makes it possible to form a heat insulating layer that has excellent peelability, drying properties, and heat insulating properties (Patent Document 5).

[0007] However, as a result of further investigations by the present inventors, it was found that although the above-mentioned existing heat insulating paints have been investigated in terms of heat insulating properties and workability, they are not sufficient in terms of non-flammability, and there is room for improvement. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-105385 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-098543 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-142002 [Patent Document 4] Japanese Patent Application Publication No. 2017-179268 [Patent Document 5] Japanese Patent Publication No. 2022-029540 Summary of the Invention [Problem to be solved by the invention]

[0009] Therefore, an object of the present invention is to provide a water-based coating composition capable of forming a coating film having excellent heat insulating properties and non-flammability, and a method for coating buildings using the same. [Means for solving the problem]

[0010] As a result of intensive research into solving the above problems, the present inventors have discovered that an aqueous coating composition comprising (A) a water-dispersible resin, (B) hollow particles, and (C) water, can be obtained by adjusting the thermal conductivity and total calorific value of a coating film formed from the coating composition to fall within a predetermined range, thereby achieving an aqueous coating composition that is easy to apply and capable of forming a coating film that is excellent in heat insulation and non-flammability, and have thereby completed the present invention.

[0011] That is, according to the present invention [1], there is provided a water-based coating composition comprising (A) a water-dispersible resin, (B) hollow particles, and (C) water, wherein the thermal conductivity of a coating film formed from said coating composition is 0.2 W / m K or less, and the total heat generation rate of a 20-minute cone calorimeter test of a test plate having a coating thickness of 1 mm formed from said water-based coating composition on an aluminum plate having dimensions of 99 ± 1.0 mm × 99 mm ± 1.0 × 0.8 mm is 8.0 MJ / m 2 The present invention provides a water-based coating composition characterized by:

[0012] Furthermore, according to present invention [2], there is provided the aqueous coating composition according to present invention [1], characterized in that the coating film formed from the aqueous coating composition contains 30% by volume or more of (B) hollow particles having a size of 25 μm or more by volume. Furthermore, according to the present invention [3], there is provided the aqueous coating composition according to the present invention [1] or [2], characterized in that the organic content in the coating film formed from the aqueous coating composition is 70 wt% or less. Furthermore, according to the present invention [4], there is provided the water-based coating composition according to any one of the present inventions [1] to [3], characterized in that the hollow particles (B) are inorganic hollow particles. Furthermore, according to the present invention [5], there is provided the water-based coating composition according to any one of the present inventions [1] to [4], characterized in that it further contains (D) an inorganic pigment. Furthermore, according to the present invention [6], there is provided the aqueous coating composition according to any one of the present inventions [1] to [5], characterized in that the water-dispersible resin (A) contains a silicone-modified acrylic resin. Furthermore, according to the present invention [7], there is provided a method for painting buildings, which comprises the steps of forming a primer layer on a substrate, applying the above-mentioned water-based paint composition to the primer layer to form an intermediate coat layer, and further forming a top coat layer on the intermediate coat layer. [Effects of the Invention]

[0013] The aqueous coating composition of the present invention has good coating workability and can form a coating film that is excellent in heat insulation and non-flammability. Furthermore, by applying a combination of a primer layer coating, an intermediate layer coating containing the aqueous coating composition of the present invention, and a top layer coating to a substrate, it is possible to produce an insulating coating laminate that not only maintains good adhesion to the substrate but also has low thermal conductivity and meets the non-flammable material standard (ISO 5660-1:2002). In other words, the aqueous coating composition of the present invention can be used in a coating method for buildings that is excellent in heat insulation and non-flammability. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention relates to a water-based coating composition that has good coating workability and is capable of forming a coating film that is excellent in heat insulation and non-flammability, and to a method of coating buildings using the same. The present invention will be described below item by item.

[0015] <Water-based paint composition> One aspect of the present invention is a water-based coating composition comprising (A) a water-dispersed resin, (B) hollow particles, and (C) water. In this specification, this water-based coating composition is also referred to as the "water-based coating composition of the present invention" or the "coating composition of the present invention." The "water-based coating composition" is a coating composition containing water as the primary solvent.

[0016] <Coating film forming components> As used herein, "film-forming components" refers to components excluding volatile components such as water and organic solvents, and are components that ultimately form a coating film. "When a coating film is formed" means when a coating film is ultimately formed by the film-forming components. "Film-forming components" can also be expressed as "non-volatile components." As used herein, the components remaining when the aqueous coating composition is dried at 130°C for 60 minutes are considered to be film-forming components. In the aqueous coating composition of the present invention, the amount of film-forming components is, for example, 38.0 to 58.0 mass%, and preferably 43.0 to 53.0 mass%.

[0017] 1.(A) Water-dispersed resin The aqueous coating composition of the present invention contains a water-dispersed resin. The "water-dispersed resin" is also referred to as "(A) water-dispersed resin" and is referred to as component (A). In this specification, a water-dispersed resin is a resin that can be distributed in water to form a heterogeneous system (e.g., an emulsion or suspension), and is distinguished from a water-soluble resin. The water-dispersed resin (A) is dispersed in the aqueous coating composition of the present invention, and may contain an emulsion resin and / or a dispersion resin. The emulsion resin refers to a water-dispersed resin obtained by emulsion polymerization. The dispersion resin refers to a self-water-dispersing resin. By making the resin water-dispersible, it is possible to increase the molecular weight.

[0018] Examples of resins that can be used in water-dispersed resins include acrylic resins, vinyl acetate resins, vinyl chloride resins, styrene-butadiene resins, epoxy resins, alkyd resins, polyester resins, silicone resins, fluorine-containing resins, polyurethane resins, and acrylic urethane resins (including two-component resins). These can be used alone or in combination of two or more. Among these, water-dispersed resins containing an acrylic component (e.g., a repeating unit) are preferred, specifically acrylic water-dispersed resins. When a resin other than acrylic is used in combination, the acrylic water-dispersed resin preferably accounts for up to 50% of the water-dispersed resin. In this specification, "acrylic component" refers to acrylic acid, methacrylic acid, and their derivatives (e.g., compounds having a (meth)acryloyl group, such as esters and amides of acrylic acid and methacrylic acid, acrylic nitrile, methacrylic nitrile, etc.). The acrylic components can be used alone or in combination of two or more.

[0019] Water-dispersible resins containing an acrylic component as a constituent element include, in addition to acrylic resins, various modified resins such as acrylic-styrene resins, silicone-modified acrylic resins, fluorine-modified acrylic resins, fatty acid-modified acrylic resins, urethane-modified acrylic resins, and epoxy-modified acrylic resins. The silicone-modified acrylic resin may contain a two-component curing silicone-modified acrylic resin. In the water-based coating composition of the present invention, it is preferable to contain a silicone-modified acrylic resin as the water-dispersible resin, from the viewpoint of improving non-flammability by reducing the content of organic components.

[0020] The "silicone-modified acrylic resin" in the present invention is not particularly limited as long as the acrylic resin is silicone-modified, and may be, for example, a resin obtained by modifying an acrylic resin having a functional group using a silicone modifier having a functional group at its terminal that can react with the functional group of the acrylic resin. Furthermore, the "silicone-modified acrylic resin" in the present invention may include a resin having an acrylic resin having a reactive functional group as the main chain and a siloxane structure in the side chain.

[0021] Examples of the silicone modifier include organopolysiloxanes having an organic group, such as dimethylpolysiloxane. Examples of the organic group include phenyl, methyl, ethyl, isopropyl, hexyl, cyclohexyl, and vinyl groups. These may be used alone or in combination of two or more.

[0022] The acrylic and modified acrylic resins contained in the aqueous coating composition of the present invention may have functional groups. These functional groups may be functional groups that remain unused in the reaction between the acrylic resin and a modifier such as silicone, or functional groups that do not contribute to the reaction. Examples of functional groups possessed by acrylic and modified acrylic resins include reactive functional groups such as hydroxyl groups, carboxyl groups, amino groups, epoxy groups, alkoxysilyl groups, and mercapto groups. The functional groups possessed by the acrylic and modified acrylic resins may be of one type or multiple types. Furthermore, the functional groups may be present at either the terminals or side chains of the acrylic and modified acrylic resins, or may be present at both the terminals and side chains.

[0023] In the aqueous coating composition of the present invention, it is preferable to use a high-silicone-modified acrylic resin that contains a large amount of silicone components as the silicone-modified acrylic resin, from the viewpoint of not only reducing the organic content but also improving the effect of reducing the heat generation, which will be described later.

[0024] In the silicone-modified acrylic resin contained in the aqueous coating composition of the present invention, the silicone modification level is preferably 15 to 55 mass% and more preferably 20 to 55 mass% in terms of the ratio of polysiloxane-derived structures to the silicone-modified acrylic resin, from the viewpoints of reducing the organic content and the heat generation. In this specification, a resin having such a silicone modification level can be referred to as a high-silicone-modified acrylic resin. The silicone-modified acrylic resin contained in the aqueous coating composition of the present invention may be a resin having the same silicone modification level, which can be used alone, or a combination of multiple resins with different silicone modification levels.

[0025] The presence or absence of the polysiloxane-derived structure can be confirmed, for example, by using Fourier transform infrared spectroscopy. The proportion of the polysiloxane-derived structure (the amount of modified silicone) can be calculated from the difference in ash weight before and after ashing the sample using a crucible or a TGA (thermogravimetric analysis) device.

[0026] The water-dispersed resin can be prepared, for example, by emulsifying the water-dispersed resin in water or by forcibly emulsifying the monomer components, using a surfactant as needed, while applying forced shear force using a high-speed agitator or the like. Alternatively, an aqueous resin dispersion can be prepared by adding a surfactant as needed to a water-dispersed resin polymerized in an organic solvent medium and then subjecting the polymer to phase inversion into water, and the organic solvent contained in the aqueous resin dispersion can be removed by distillation or the like as needed. Alternatively, an aqueous resin dispersion can be prepared by performing polymerization in water using water as the medium.

[0027] The water-dispersible resin can be obtained by polymerization of the constituent monomer components, and is preferably obtained by emulsion polymerization of the constituent monomer components. The monomer components may be used alone or in combination of two or more.

[0028] Examples of the monomer component include alkyl (meth)acrylate, alkoxyalkyl (meth)acrylate, polymerizable ultraviolet absorber, polymerizable radical scavenger, cyclic aliphatic monomer, polymerizable cross-linking component (also referred to as cross-linking monomer), reactive emulsifier, hydroxyl group-containing monomer, aromatic monomer, acid group-containing monomer, nitrogen atom-containing monomer, oxo group-containing monomer, fluorine atom-containing monomer, etc. The monomer component may be either an acrylic component or a non-acrylic component.

[0029] Examples of alkyl (meth)acrylates include C1-20 alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, n-lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate.

[0030] Examples of the alkoxyalkyl (meth)acrylate include C1-12 alkoxy C1-12 alkyl (meth)acrylates such as 2-methoxyethyl (meth)acrylate.

[0031] Examples of hydroxyl group-containing monomers include hydroxyl group-containing (meth)acrylates such as hydroxyalkyl (meth)acrylates [e.g., hydroxy C2-10 alkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, preferably hydroxy C2-6 alkyl (meth)acrylate, and more preferably hydroxy C2-4 alkyl (meth)acrylate], and (meth)acrylates of polyols having three or more hydroxy groups [e.g., (meth)acrylates of tri- or hexahydroxy C3-10 polyols such as glycerin mono(meth)acrylate].

[0032] Examples of aromatic monomers include styrene-based monomers [for example, styrene, α-alkylstyrenes (for example, α-C alkylstyrenes such as α-methylstyrene), alkylstyrenes (for example, C alkylstyrenes such as vinyltoluene), halostyrenes (for example, chlorostyrene)], aromatic (meth)acrylates [for example, aryl (meth)acrylates (for example, C aryl (meth)acrylates such as phenyl (meth)acrylate), aralkyl (meth)acrylates (for example, C aryl C alkyl (meth)acrylates such as benzyl (meth)acrylate and phenethyl (meth)acrylate), aryloxyalkyl methacrylates (for example, C aryloxy C alkyl methacrylates such as phenoxyethyl methacrylate)], and the like.

[0033] Examples of the acid group-containing monomer include carboxylic acid group-containing monomers and sulfonic acid group-containing monomers. Examples of the carboxylic acid group-containing monomer include unsaturated monocarboxylic acids (e.g., aliphatic unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid) and unsaturated dicarboxylic acids (e.g., aliphatic unsaturated monocarboxylic acids such as maleic acid and fumaric acid). Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid. The acid group-containing monomer may be anionized (or may form a salt).

[0034] Examples of the nitrogen atom-containing monomer include (meth)acrylamide compounds, nitrogen atom-containing (meth)acrylate compounds, N-vinylpyrrolidone, (meth)acrylonitrile, etc. Examples of the (meth)acrylamide compounds include (meth)acrylamide, diacetone (meth)acrylamide, N-monomethyl (meth)acrylamide, N-monoethyl (meth)acrylamide, N,N-dimethyl (meth)acrylamide, Nn-propyl (meth)acrylamide, N-isopropyl (meth)acrylamide, methylene bis (meth)acrylamide, N-methylol (meth)acrylamide, N-butoxymethyl (meth)acrylamide, dimethylaminoethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, and diacetone (meth)acrylamide, and other N-substituted (meth)acrylamides [e.g., N-alkyl (meth)acrylamides (e.g., N,N-diC alkyl (meth)acrylamides)]. Examples of the nitrogen atom-containing (meth)acrylate compound include N-substituted aminoalkyl (meth)acrylates such as dimethylaminoethyl (meth)acrylate and diethylaminoethyl (meth)acrylate (for example, N,N-diC1-4 alkylamino C2-4 alkyl (meth)acrylate).

[0035] Examples of oxo group-containing monomers include (di)ethylene glycol (methoxy)(meth)acrylates such as ethylene glycol (meth)acrylate, ethylene glycol methoxy(meth)acrylate, diethylene glycol (meth)acrylate, and diethylene glycol methoxy(meth)acrylate.

[0036] Examples of the fluorine atom-containing monomer include fluorine atom-containing acrylic monomers [for example, fluoroalkyl(meth)acrylates (for example, fluoroC1-10 alkyl(meth)acrylates such as trifluoroethyl(meth)acrylate, tetrafluoropropyl(meth)acrylate, and octafluoropentyl(meth)acrylate, preferably fluoroC2-6 alkyl(meth)acrylate)].

[0037] The water-dispersible resin may be a water-dispersible resin containing a cyclic aliphatic monomer as a constituent element. The cyclic aliphatic monomer is a monomer having an alicyclic structure (a saturated or unsaturated carbon ring having no aromaticity, such as a cycloalkyl group, preferably a C4-20 cycloalkyl group, more preferably a C4-10 cycloalkyl group). The cyclic aliphatic monomer may be either an acrylic component or a non-acrylic component, but is preferably an acrylic component. Examples of cyclic aliphatic monomers include alicyclic (meth)acrylates [for example, cycloalkyl (meth)acrylates (for example, C4-20 cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, preferably C4-10 cycloalkyl (meth)acrylates), alkyl cycloalkyl (meth)acrylates (for example, C1-4 alkyl C4-10 cycloalkyl (meth)acrylates such as 4-methylcyclohexyl (meth)acrylate), cycloalkyl alkyl (meth)acrylates (for example, C4-10 cycloalkyl C1-4 alkyl (meth)acrylates such as cyclohexylmethyl (meth)acrylate, cyclohexylethyl (meth)acrylate, cyclohexylpropyl (meth)acrylate, 4-methylcyclohexylmethyl (meth)acrylate), and crosslinked cyclic (meth)acrylates (for example, isobornyl (meth)acrylate, adamantyl (meth)acrylate, etc.)]. The cycloaliphatic monomers may be used alone or in combination of two or more.

[0038] The water-dispersible resin may contain a non-acrylic component as a constituent element (e.g., a repeating unit). The non-acrylic component is a component other than the acrylic component, and examples thereof include, in addition to styrene, carboxyl group-containing monomers such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, and vinyl versatic acid; aromatic monomers such as methylstyrene, chlorostyrene, methoxystyrene, and vinyltoluene; olefinic monomers such as ethylene and propylene; vinyl monomers such as vinyl acetate and vinyl chloride; amide monomers such as maleic acid amide; alkoxysilyl group-containing monomers such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane; dialkyl fumarate, allyl alcohol, vinylpyridine, and butadiene.

[0039] The water-dispersed resin may be a resin having a single phase structure or a resin having a heterogeneous phase structure. In this specification, a resin having a heterogeneous phase structure refers to a resin in which different monomer compositions constitute multiple regions and exist in a domain or layer configuration. Among these, a resin in which multiple regions consisting of one or more monomer compositions exist in a layer configuration is also referred to as a "resin having a multilayer structure." Furthermore, the inner layer of the water-dispersed resin particles having this multilayer structure is sometimes referred to as a "core" and the outer layer as a "shell," and this is sometimes referred to as a resin having a core-shell structure. On the other hand, a resin having a single phase structure is a resin in which the monomer composition is not separated into domains or layers, preferably a resin in which the monomer composition is uniformly distributed. A single phase structure can be prepared by a single-stage emulsion polymerization, while a heterogeneous phase structure can be prepared by a multistage emulsion polymerization. A heterogeneous phase structure has, for example, 2 to 5 layers or domains, preferably 2 to 3 layers or domains.

[0040] The heterogeneous phase structure can be used, for example, to prepare a water-dispersed resin having two or more glass transition temperatures. This allows the heterogeneous phase structure to be composed of a hard layer or domain (hard layer or domain) and a soft layer or domain (soft layer or domain). For example, in the case of water-dispersed resin particles having a multi-layer structure, the outer layer (the outermost layer in the case of three or more layers) may be a hard layer, and the inner layer (a layer other than the outermost layer in the case of three or more layers) may be a soft layer, or the outer layer (the outermost layer in the case of three or more layers) may be a soft layer, and the inner layer (a layer other than the outermost layer in the case of three or more layers) may be a hard layer. Furthermore, when there are multiple inner layers, hard and soft layers may be present between the inner layers.

[0041] The emulsion polymerization of the monomer components can be carried out in the presence of an emulsifier. Examples of such methods include a method in which the monomer components are mixed (dropped, etc.) into a solvent (solution) containing an emulsifier and polymerized, and a method in which pre-emulsified monomer components are mixed (dropped, etc.) into a solvent and polymerized. Typically, aqueous solvents such as water or a mixture of water and a water-soluble organic solvent can be used as the solvent. Examples of water-soluble organic solvents include alcohols, such as C1-4 alcohols such as methanol and ethanol. The water-soluble organic solvents can be used alone or in combination of two or more. Examples of methods for producing a heterophase structure include a multistage emulsion polymerization method in which the above-mentioned emulsion polymerization is repeatedly performed.

[0042] Examples of the emulsifier include the reactive emulsifiers described above, as well as anionic emulsifiers, nonionic emulsifiers, cationic emulsifiers, amphoteric emulsifiers, polymeric emulsifiers, etc. The emulsifiers may be used alone or in combination of two or more.

[0043] Examples of anionic emulsifiers include alkyl sulfate salts such as ammonium dodecyl sulfate and sodium dodecyl sulfate; alkyl sulfonate salts such as ammonium dodecyl sulfonate and sodium dodecyl sulfonate; alkyl aryl sulfonate salts such as ammonium dodecyl benzene sulfonate and sodium dodecyl naphthalene sulfonate; polyoxyethylene alkyl sulfate salts; polyoxyethylene alkyl aryl sulfate salts; dialkyl sulfosuccinates; aryl sulfonic acid-formalin condensates; and fatty acid salts such as ammonium laurate and sodium stearylate.

[0044] Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkyl ethers, and polyoxyethylene alkyl ethers. Diethylene alkyl aryl ether, polyethylene glycol and polypropylene glycol sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester esters, fatty acid monoglycerides, condensation products of ethylene oxide and aliphatic amines, etc. can be done.

[0045] Examples of cationic emulsifiers include alkyl ammonium salts such as dodecyl ammonium chloride.

[0046] Examples of amphoteric emulsifiers include betaine ester emulsifiers.

[0047] Examples of polymeric emulsifiers include poly(meth)acrylates such as sodium polyacrylate; polyvinyl alcohol; polyvinylpyrrolidone; polyhydroxyalkyl(meth)acrylates such as polyhydroxyethyl acrylate; and polymers containing one or more of the monomers constituting these polymers as copolymerization components.

[0048] A polymerization initiator can be used when polymerizing the monomer components. As the polymerization initiator, those that have been generally used in radical polymerization can be used, and among them, water-soluble initiators are preferred.

[0049] The water-dispersible resin may contain a crosslinking component as a constituent unit thereof, and / or the water-based coating composition of the present invention may contain a crosslinking component as a crosslinking agent or the like (separate from the water-dispersible resin). In this specification, the crosslinking component is a component that forms crosslinks in the resin that constitutes the coating film. The crosslinking component may be one or both of interparticle crosslinking and intraparticle crosslinking.

[0050] The water-dispersible resin may contain a polyurethane component, and / or the water-based coating composition of the present invention may contain a polyurethane component (separate from the water-dispersible resin). The polyurethane component is preferably a hydrophilic group-containing polyurethane, and more preferably a composite resin in which a hydrophilic group-containing polyurethane is bonded to a vinyl copolymer. Examples of hydrophilic groups include carboxyl groups, carboxylate groups, sulfonic acid groups, sulfonate groups, and / or anionic groups in which a portion or all of these groups are neutralized with a basic compound such as ammonia or triethylamine; tertiary amino groups and / or cationic groups in which a portion or all of these groups are neutralized with organic acids such as acetic acid or maleic acid, sulfonic acids, or inorganic acid salts such as hydrochloric acid and / or sulfuric acid; and nonionic groups such as polyoxyalkylene groups such as polyoxyethylene groups and polyoxypropylene groups. The inclusion of a polyurethane component improves flexibility and suppresses coating film abnormalities (e.g., cracking) caused by repeated environmental temperature changes.

[0051] From the viewpoint of film-forming properties, the water-dispersible resin preferably has a glass transition temperature (Tg) of −20° C. to 40° C., more preferably −10° C. to 30° C. In the present invention, Tg is calculated using the following FOX formula. [FOX formula] 1 / Tg=W1 / Tg1+W2 / Tg2+···+Wi / Tgi+···+Wn / Tgn In the FOX formula, Tg written in the denominator on the left side represents the glass transition temperature (unit: K) of the polymer component consisting of N types of monomers, Tg(1, 2, i, N) represents the glass transition temperature (unit: K) of each monomer, W(1, 2, i, N) is the mass fraction of each monomer, and the relationship W1 + W2 +··· + Wi +··· + Wn = 1 holds. Here, the glass transition temperature of a monomer means the glass transition temperature of its homopolymer.

[0052] In this specification, the glass transition temperature (Tg) of a resin, including a water-dispersible resin, refers to a value measured by DSC in accordance with JIS K7121: 2012. Specifically, the glass transition temperature can be determined by placing an approximately 10 mg piece of resin in an aluminum pan for measurement and performing DSC measurement under the following measurement conditions. (Measurement temperature conditions) 1st temperature rise: -80℃ to 220℃ (20℃ / min) Temperature drop condition: 220℃~-80℃(50℃ / min) 2nd temperature rise: -80℃ to 220℃ (10℃ / min)

[0053] From the viewpoint of water resistance, the water-dispersible resin preferably has a weight-average molecular weight of 100,000 or more. Alternatively, although the molecular weight of resins with a weight-average molecular weight of 300,000 or more or crosslinked resins is generally unmeasurable, such water-dispersible resins can also be used as preferred resins in the aqueous coating composition of the present invention. In this specification, the weight-average molecular weight of the water-dispersible resin is a value measured by gel permeation chromatography (GPC), using polystyrene as the standard substance and tetrahydrofuran as the mobile phase.

[0054] The water-dispersed resin may be in the form of resin particles. In the aqueous coating composition of the present invention, from the viewpoint of water resistance, the volume average particle size of the resin particles is preferably 20 to 200 μm, more preferably 20 to 150 μm.

[0055] In the aqueous coating composition of the present invention, the lower the content of the water-dispersible resin and the more hollow particles there are in the composition, the better it is in terms of non-flammability and heat insulation. However, if the content of the water-dispersible resin is reduced, the coating workability and the appearance of the coating film will be impaired. Water-based coating composition The content of the water-dispersible resin therein is preferably 10.0 to 30.0 mass%, more preferably 15.0 to 25.0 mass%, and even more preferably 17.0 to 23.0 mass%. The water-dispersible resin may be used alone or in combination of two or more.

[0056] 2.(B) Hollow particles The aqueous coating composition of the present invention contains (B) hollow particles. Furthermore, "hollow particles" are referred to as component (B) and are also referred to as "(B) hollow particles." In this specification, hollow particles are particles having one or more cavities therein. Examples of hollow particles include spherical hollow particles, fibrous hollow particles, tubular hollow particles, and sheet-shaped hollow particles. These hollow particles may be used alone or in combination of two or more types.

[0057] Hollow particles can be classified by material. Examples include hollow particles made of organic materials such as resin, and hollow particles made of inorganic materials such as glass, silica, and alumina. These hollow particles may be used alone or in combination of two or more types. Depending on the material, hollow particles may be called, for example, glass beads, glass balloons, glass bubbles, fly ash balloons, shirasu balloons, silica balloons, and aluminosilicate balloons. Hollow particles may be used alone or in combination of two or more types. In addition, hollow particles whose surfaces have been treated can also be used. For example, treatments with calcium carbonate or organosilanes can be used, and the surface treatment can contribute to improving the dispersibility of hollow particles and increasing the filling rate.

[0058] The aqueous coating composition of the present invention preferably contains hollow particles made of an inorganic material (hereinafter referred to as "inorganic hollow particles"). The inorganic hollow particles do not necessarily contain no organic components, and it is acceptable for the inorganic hollow particles to contain trace amounts of organic components unintentionally present when they are prepared. Adding a certain amount of inorganic hollow particles to the aqueous coating composition not only provides a heat insulating effect, but also reduces the content of the organic components described below, thereby further enhancing the non-flammability effect.

[0059] Examples of inorganic materials constituting the outer shell of inorganic hollow particles include glass, silica, alumina carbon, ceramic, titanium oxide, magnesium oxide, zinc oxide, zirconium oxide, and metal halides such as magnesium fluoride. Examples of glass include glasses such as sodium silicate glass, aluminum silicate glass, sodium borosilicate glass, and shirasu (white sand). The inorganic hollow particles may be used alone or in combination of two or more. In the water-based coating composition of the present invention, it is preferable to contain glass beads among the inorganic hollow particles from the viewpoints of versatility and specific gravity (lightweight).

[0060] While the larger the particle size, the better the heat insulating properties, if the particle size is too large, unevenness will occur on the surface of the coating film formed from the coating composition of the present invention, which may result in a decrease in gloss of the topcoat layer due to the unevenness.Therefore, in the aqueous coating composition of the present invention, the 50% particle size of the hollow particles is preferably 20 to 200 μm, more preferably 30 to 150 μm, and even more preferably 30 to 100 μm.Furthermore, from the viewpoint of preventing the occurrence of unevenness on the surface of the coating film formed from the coating composition of the present invention and further preventing a decrease in gloss of the topcoat layer due to such unevenness, the 90% particle size of the hollow particles is preferably 300 μm or less, more preferably 200 μm or less.

[0061] In the present invention, the 50% particle size refers to the 50% particle size (d50) of the volume-based particle size distribution, and the 90% particle size refers to the 90% particle size (d90) of the volume-based particle size distribution, and can be determined from the particle size distribution measured using a particle size distribution analyzer (e.g., a laser diffraction / scattering particle size distribution analyzer). The particle size in the present invention is expressed as the spherical equivalent diameter measured by the laser diffraction / scattering method. In this specification, the particle size can be measured using a wet laser diffraction particle size analyzer (e.g., a SALD-7500NANO manufactured by Shimadzu Corporation).

[0062] The hollow particles have a true density of 0.10 to 1.00 g / cm 3 is preferably 0.10 to 0.50 g / cm 3 The true density can be measured using a pycnometer (a gas phase displacement true density meter, for example, AccuPycII1340 manufactured by Micromeritics).

[0063] The hollow particles preferably have a pressure resistance of 3.0 MPa or more. The pressure resistance is defined in ASTM D 3102-78, and is determined by placing an appropriate amount of hollow particles in glycerin, applying pressure, and measuring the pressure at which 10% by volume of the particles breaks. If the pressure resistance is less than 3.0 MPa, the hollow particles may be damaged by the shear force during mixing when preparing the paint or the pressure during application, and the desired heat insulation may not be achieved.

[0064] In the aqueous coating composition of the present invention, the proportion of hollow particles in the film-forming components is 70.0 to 90.0 vol%, preferably 75.0 to 85.0 vol%. From the viewpoint of imparting sufficient heat insulation to the coating film formed from the aqueous coating composition of the present invention, the proportion of hollow particles in the film-forming components in the aqueous coating composition is 70.0 vol% or more. Furthermore, if the proportion of hollow particles in the film-forming components in the coating composition exceeds 85.0 vol%, the coating film surface becomes uneven and the corrosion resistance and water resistance of the coating film decrease, which is undesirable. The proportion of hollow particles in the film-forming components in the aqueous coating composition of the present invention can be calculated from the composition and specific gravity of each component.

[0065] In the aqueous coating composition of the present invention, when the hollow particles include inorganic hollow particles, the proportion of the inorganic hollow particles to the total hollow particles is preferably 40.0% or more, and more preferably 70.0% or more, on a volume basis.

[0066] From the viewpoint of imparting heat insulating properties to a coating film formed from the aqueous coating composition of the present invention, when the total volume of hollow particles contained in the coating film-forming components in the aqueous coating composition of the present invention is taken as 100 volume %, it is preferable that the aqueous coating composition of the present invention contain 30 volume % or more of hollow particles having a 50% particle size of 25 μm or more, and it is even more preferable that the aqueous coating composition contain 50 volume % or more of hollow particles having a 50% particle size of 25 μm or more.

[0067] 3.(C)Water The aqueous coating composition of the present invention contains (C) water. The term "water" is also used to refer to the (C) component as "(C) water." Water is used to disperse or dissolve various components in the coating, including (A) the water-dispersible resin and (B) the hollow particles. The water used in the aqueous coating composition of the present invention is not particularly limited, but preferred examples include tap water, ion-exchanged water, distilled water, and other pure water. Furthermore, when storing the coating composition for a long period of time, water sterilized by ultraviolet irradiation or the like may be used to prevent the growth of mold and bacteria. The amount of water in the aqueous coating composition of the present invention is preferably 40.0 to 65.0 mass%, more preferably 50.0 to 65.0 mass%, and even more preferably 50.0 to 60.0 mass%. The aqueous coating composition of the present invention may contain a solvent other than (C) water.

[0068] 4. (D) Inorganic pigments The aqueous coating composition of the present invention may further contain (D) an inorganic pigment. Furthermore, the "inorganic pigment" is referred to as component (D) and is also referred to as "(D) inorganic pigment." Inorganic pigments include colored (inorganic) pigments, extender (inorganic) pigments, and functional (inorganic) pigments, with extender pigments being preferred from the viewpoint of coating workability. Examples of extender pigments include barium sulfate, calcium carbonate, aluminum hydroxide, silica, talc, mica, and hydrated aluminum silicate (kaolin). From the viewpoint of heat insulation, it is preferable to contain silica. Examples of silica include fume silica and silica aerogel. In the aqueous coating composition of the present invention, the inorganic pigment may be used alone or in combination of two or more. Note that (D) inorganic pigments do not include those having a hollow structure.

[0069] In the aqueous coating composition of the present invention, from the viewpoint of ensuring heat insulating and non-flammable effects while also achieving ease of coating workability, the volume concentration (PVC) of all pigments in the coating film-forming components is preferably 60 to 90%, more preferably 70 to 89% by mass, and even more preferably 75 to 89% by mass, where "all pigments" refers to the total pigments consisting of (B) hollow particles, (D) inorganic pigments, and other pigment components.

[0070] In the water-based coating composition of the present invention, the 50% particle size (d50) of the inorganic pigment in the coating film-forming components is preferably 0.1 μm to 20.0 μm from the viewpoint of coating workability.

[0071] 5.Organic content In the aqueous coating composition of the present invention, the organic content of the film-forming components is preferably 70% by mass or less. In this specification, "organic content" refers to the proportion excluding inorganic content. Having the organic content in the film-forming components within this range enhances non-flammability and allows the preparation of a coating with good application properties. The organic content in the film-forming components is preferably 30 to 65% by mass, more preferably 40 to 60% by mass. Good application properties include good application properties, such as roller application and trowel application. The organic content can be analyzed using a simultaneous differential thermal and thermogravimetric (TG-DTA) analyzer. In TG-DTA analysis, the dry solids content of the aqueous coating composition of the present invention is measured, and the organic content can be calculated from the weight change.

[0072] 6. Thermal conductivity of water-based paint compositions The aqueous coating composition of the present invention preferably has a thermal conductivity of 0.2 W / m·K or less, more preferably 0.15 W / m·K or less, and even more preferably 0.10 W / m·K or less. If the thermal conductivity of the coating film formed from the aqueous coating composition is 0.2 W / m·K or less, the coating thickness can be reduced while improving the heat insulating effect. There is no particular lower limit for the thermal conductivity of the coating film formed from the aqueous coating composition, but it is preferably 0.02 W / m·K or more. The method for measuring thermal conductivity will be explained in the examples.

[0073] 7. Total heat generation of water-based paint composition The water-based coating composition of the present invention was applied to an aluminum plate measuring 99±1.0 mm x 99±1.0 mm x 0.8 mm, and the total heat generated by a 20-minute cone calorimeter test on a test plate with a coating thickness of 1 mm was 8.0 MJ / m 2 Preferably, it is 6.0 MJ / m or less. 2 More preferably, it is 4.0 MJ / m or less. 2 In the case of a coating film formed from the water-based coating composition of the present invention, the total heat generation rate of a test plate having a coating thickness of 1 mm formed on an aluminum plate having dimensions of 99±1.0 mm x 99±1.0 mm x 0.8 mm in a 20-minute cone calorimeter test is 8.0 MJ / m2 The non-flammable effect can be enhanced if the content is below the following: The method for measuring the calorific value will be explained in the Examples.

[0074] Other resins that are optionally included In addition to the resins contained in the (A) water-dispersible resin and hollow particles of the resin material (referred to as (B1) in the resin material hollow particles), the aqueous coating composition of the present invention can contain any resin commonly used in the coatings industry. Specific examples include acrylic resins, silicone resins, silicone-modified acrylic resins, styrene-acrylic copolymer resins, polyester resins, fluororesins, rosin resins, petroleum resins, coumarone resins, phenolic resins, urethane resins, melamine resins, urea resins, epoxy resins, cellulose resins, xylene resins, alkyd resins, aliphatic hydrocarbon resins, butyral resins, maleic acid resins, fumaric acid resins, vinyl resins, amine resins, and ketimine resins. Water-soluble resins may also be included. Resins other than the (A) water-dispersible resin and the (B1) hollow particles of the resin material will be referred to as "(P) other resins" hereinafter.

[0075] In the aqueous coating composition of the present invention, Water-based coating composition The total amount of resins therein is, for example, 15.0 to 25.0% by mass, where the total amount of resins refers to the combined amount of (A) water-dispersible resin and (P) other resins that may be contained in some cases.

[0076] Other optional ingredients Other optional components that may be incorporated into the aqueous coating composition of the present invention include surface conditioners, wetting agents, dispersants, emulsifiers, thickeners, anti-settling agents, anti-skinning agents, anti-dripping agents, antifoaming agents, anti-color separation agents, viscosity modifiers, rheology control agents, leveling agents, antifoaming agents, drying agents, plasticizers, preservatives, anti-mold agents, antibacterial agents, insecticides, light stabilizers, ultraviolet absorbers, antistatic agents, conductivity imparting agents, film-forming aids, antifreeze agents, solvents, rust inhibitors, adhesion imparting agents, reaction accelerators, anti-algae agents, and the like, which may be appropriately blended depending on the purpose.

[0077] The aqueous coating composition of the present invention can be used alone as a coating material for painting the interior and exterior surfaces of buildings. The aqueous coating composition of the present invention can also be used as a part of a laminate consisting of multiple layers, such as a primer layer coating material, an intermediate layer coating material, or a top coat layer coating material. <Method for painting buildings using the above water-based paint composition>

[0078] The method for coating buildings according to the present invention comprises the steps of forming a primer layer on a substrate, applying the aqueous coating composition described above to the primer layer to form an intermediate coating layer, and then forming a topcoat layer on the intermediate coating layer. In one preferred embodiment of the present invention, by using a sealer or primer coating for the primer layer, a coating containing the aqueous coating composition of the present invention for the intermediate coating layer, and a coating containing a silicone resin for the topcoat layer in each of these steps, it is possible to produce a heat-insulating coating laminate that not only maintains good adhesion to the substrate but also has low thermal conductivity and meets the non-combustible material standard (ISO 5660-1:2002). In other words, the coating method of the present invention provides a method for coating buildings that is easy to apply and has excellent heat insulation and non-combustibility.

[0079] The method for coating buildings in the present invention includes applying a primer layer paint to a substrate to form a primer layer, applying an intermediate coat layer paint to the primer layer to form an intermediate coat layer, and applying a top coat layer paint to the intermediate coat layer to form a top coat layer, thereby completing a multi-layer paint laminate. Here, the intermediate coat layer paint contains at least one of the above-mentioned water-based coating compositions.

[0080] There are no particular limitations on the objects to be painted using the painting method of the present invention, but it is suitable as a paint for the interior and exterior of buildings, structures, etc. Specific interior and exterior parts to be painted include, for example, roofs, exterior walls, interior walls, ceilings, doors, etc.

[0081] Examples of materials to be coated include plastic substrates such as epoxy resin, ABS resin, polycarbonate, polyvinyl chloride, polystyrene, acrylic resin, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyolefin, and polypropylene (PP). Metal substrates include steel, galvanized steel, electrogalvanized steel, tin-plated steel, stainless steel, magnesium alloy, titanium, titanium alloy, galvanized iron, and colored galvanized iron. Non-ferrous metal substrates include aluminum, aluminum alloy, and stainless steel. Inorganic substrates include cement, mortar, concrete, slate, gypsum, calcium silicate, glass, ceramic, calcium carbonate, marble, and artificial marble. Wood substrates, paper substrates, and composite substrates that combine two or more of these substrates. Examples of composite substrates include wood fiber-reinforced cement boards, fiber-reinforced cement boards, and fiber-reinforced cement / calcium silicate board composites. Metal substrates that have undergone various surface treatments or oxidation treatments, and plastic substrates whose surfaces are coated with inorganic materials (e.g., glass-coated plastic substrates), are also included.

[0082] The substrate may have various shapes, for example, two-dimensional substrates such as films, sheets, and plates, and three-dimensional substrates that are complex three-dimensional objects, etc. The surface of the substrate may be smooth or may have irregularities.

[0083] The surface of the substrate may be subjected to pretreatments such as degreasing, chemical conversion treatment, and polishing, or may be coated with a sealer or primer. For example, when the substrate is a substrate (particularly a porous substrate) that may excessively absorb paint, such as a ceramic building material, the surface of the substrate may be coated with a sealer, and a sealer layer may be formed on the substrate. Also, when the substrate is a metal building material, the surface of the substrate may be coated with a primer, and a primer layer may be formed on the substrate. When the substrate has an old paint film on its surface, the primer layer can be formed by painting the substrate surface, including the old paint film, with a primer layer paint.

[0084] The primer and topcoat paints used in the respective steps of forming the primer and topcoat layers can be any of a variety of conventionally known paints, such as organic solvent-based paints using an organic solvent as the main solvent, water-based paints using water as the main solvent, solventless paints, and various enamel or clear powder paints. The primer and topcoat paints typically contain a resin, including acrylic resins, silicone resins, silicone-modified acrylic resins, styrene-acrylic copolymer resins, polyester resins, fluororesins, rosin resins, petroleum resins, coumarone resins, phenolic resins, urethane resins, melamine resins, urea resins, epoxy resins, cellulose resins, xylene resins, alkyd resins, aliphatic hydrocarbon resins, butyral resins, maleic acid resins, fumaric acid resins, vinyl resins, amine resins, and ketimine resins. These resins may be used alone or in combination.

[0085] In the above-mentioned paint laminate containing the aqueous paint composition of the present invention in the intermediate coat layer, from the viewpoint of adhesion to the substrate, it is preferable to use a paint containing epoxy, acrylic, urethane, ketimine or modified products thereof as the paint for the primer layer.

[0086] In the above-mentioned paint laminate containing the aqueous paint composition of the present invention in the intermediate coat layer, from the viewpoint of reducing the energy consumption of buildings, etc., it is preferable that the paint for the top coat layer contains a resin with a high heat-shielding effect. For example, a paint containing a fluororesin, a silicone resin, etc. can be used. Among them, an aqueous fluororesin, an aqueous silicone resin, etc. are preferred.

[0087] The primer layer paint and the top coat layer paint may contain, as necessary, components other than the resin, such as curing agents, colorants, UV absorbers, light stabilizers, rheology modifiers, leveling agents, surface tension modifiers, antioxidants, plasticizers, rust inhibitors, solvents, fillers, pH adjusters, antifoaming agents, charge control agents, photopolymerization initiators, photosensitizers, polymerization inhibitors, stress relaxation agents, penetrating agents, light-guiding materials, lustrous materials, magnetic materials, phosphors, waxes, film-forming aids, antifreeze agents, adhesion promoters, reaction accelerators, anti-algae agents, etc. The above paints can be prepared by mixing various components appropriately selected as needed.

[0088] In the step of forming an intermediate coat layer, at least one of the aqueous coating compositions of the present invention is used for the intermediate coat layer paint. The aqueous coating composition of the present invention used for the intermediate coat layer paint may also be contained in the primer coat layer paint and / or the top coat layer paint.

[0089] The primer layer, intermediate coat layer, and top coat layer can be applied by known coating means, such as brush coating, roller coating, trowel coating, spatula coating, air spray coating, airless coating, lysine gun coating, tile gun coating, etc.

[0090] In the coating method of the present invention, the primer layer, intermediate layer, and top coat layer may each be a single layer, or multiple layers may be formed. For example, a four-layer laminate can be produced by forming a primer layer (single layer), then an intermediate layer (single layer), and then two top coat layers. To further improve heat insulation, it is preferable to have at least two top coat layers.

[0091] In the coating method of the present invention, coating and drying at room temperature (temperature 0°C to 40°C, humidity 85% or less) are preferred, but factory line coating (drying) such as forced drying at 50°C is also possible.

[0092] In the coating method of the present invention, the thickness of each layer is not particularly limited, but for example, the thickness of the undercoat can be 5.0 μm to 40.0 μm, the intermediate coat 750 μm to 2000 μm, and the top coat 20 μm to 100 μm.

[0093] In the coating method of the present invention, a paint laminate that meets the non-flammable material standard (compliant with ISO 5660-1:2002) can be produced, for example, by using a sealer paint for the primer layer, a paint containing the water-based paint composition of the present invention for the intermediate coat layer, and a paint containing a silicone resin for the top coat layer in each of the steps. Note that various known sealer paints can be used for the sealer coating method for the primer layer, and various known silicone resin-containing paints can be used for the silicone resin-containing top coat layer.

[0094] The coating laminate obtained by the coating method of the present invention has good coating workability, so that roller coating or trowel coating can be applied, and the total heat generation amount in a 20-minute cone calorimeter test based on the non-combustible material standard (ISO 5660-1:2002) is 8.0 MJ / m 2 Because of the following, the coating method of the present invention can provide a paint laminate with excellent flame retardancy. Furthermore, by applying the water-based paint composition of the present invention to a portion of the laminate, the laminate also has excellent heat insulating properties. [Example]

[0095] The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" and "%" are based on mass unless otherwise specified.

[0096] <Analysis values ​​for each material> "d50" refers to the 50% particle size (50% cumulative diameter) of the volumetric particle size distribution measured using a wet laser diffraction particle size distribution analyzer (Shimadzu Corporation). From the same particle size distribution, the proportion of particles with a volumetric size of 25 μm or larger was calculated for each (B) hollow particle or each (D) inorganic pigment, and this was designated as the "proportion of particles of 25 μm or larger." The proportion of organic matter in each material was calculated using a simultaneous thermogravimetry and differential thermal analysis (TG-DTA) device. (TG-DTA measurement analysis conditions) Equipment: Hitachi High-Tech Science Corporation Conditions: The amount of solvent remaining after evaporation was taken as 100%, and the sample was heated to 800°C in an air atmosphere. The amount remaining at 780°C was calculated as ash.

[0097] <Material> (A) Water-dispersed resin The following Resin A and Resin B are synthetic resin dispersions, the details of which are as follows: The proportion of organic content in the resin is a value calculated by TG-DTA measurement. Resin A: Silanol group-containing acrylic resin dispersion (organic content in the resin: 92%, resin volume average particle size: 50 nm, non-volatile content in the dispersion: 35%) Resin B: Acrylic resin dispersion (organic content in the resin: 100%, resin volume average particle size: 100 nm, non-volatile content in the dispersion: 40%) (B) Hollow particle Details of each hollow particle are as follows. Glass beads A: d50 = 65 μm (93% of particles are 25 μm or larger), specific gravity 0.13 Glass beads B: d50 = 60 μm (particles over 25 μm: 89%), specific gravity 0.20 Glass beads C: d50 = 35 μm (70% of particles are 25 μm or larger), specific gravity 0.22 Glass beads D: d50 = 20 μm (40% of particles are 25 μm or larger), specific gravity 0.46 Glass beads E: d50 = 12 μm (particles over 25 μm: 4.5%), specific gravity 1.1 Resin beads F: inorganic coated plastic balloon, d50 = 70 μm (particle ratio of 25 μm or larger: 94%, organic ratio: 36.1%), specific gravity: 0.13 (D) Inorganic pigments Details of each inorganic pigment are as follows: Fumed silica: d50 = 8 μm (0% particles over 25 μm), specific gravity 2.2 Silica aerogel: d50 = 1 μm (0% of particles over 25 μm), specific gravity 0.1 Precipitated barium sulfate: d50 = 1 μm (0% of particles over 25 μm), specific gravity 4.2 Kaolin: d50 = 2 μm (0% of particles over 25 μm), specific gravity 2.7 (others) Other material details are as follows: Viscosity modifier: Primal RM-8W (DOW, urethane associative viscosity modifier), non-volatile content 21%, organic content 100%, Antifoaming agent: SN Defoamer 1313 (San Nopco, a mixture of silicone compounds, polyoxyalkylene-type nonionic surfactants, etc.) 100% non-volatile, 100% organic. Dispersant: Emulgen A-90 (Kao Corporation, polyoxyethylene distyrenated phenyl ether) non-volatile content 99% or more, organic content 100%

[0098] <Paint preparation> Each paint was obtained by measuring the above materials and thoroughly mixing them according to the formulations shown in Tables 1 and 2. Note that in the following comparative examples and examples, no special flame retardants containing phosphorus, nitrogen, etc. were added.

[0099] <Evaluation method and test results> The heat insulation, flammability, and paintability were evaluated as follows. The test results are shown in Tables 1 and 2. For materials with thermal conductivity exceeding 0.20 W / (m K), no other evaluations were performed.

[0100] <Thermal insulation> The paint was poured into a Teflon (registered trademark) mold and dried at 23°C and 50% relative humidity for 24 hours, then in a 50°C dryer for 4 hours, and then removed from the mold. After further drying in a 50°C dryer for 24 hours, test pieces measuring 20 mm square or more and 3 mm or more in thickness were prepared. Measurements were performed on the test pieces in a 23°C environment using a hot disc thermal property measuring device (TPS2500S) manufactured by Kyoto Electronics Manufacturing Co., Ltd. From the thermal conductivity obtained, the thermal insulation was evaluated according to the following criteria. ◎:0.10W / (m·K) or less ○: Over 0.10W / (m K) and 0.20W / (m K) or less ×: Exceeds 0.20W / (m·K)

[0101] <Flammability> The paint was applied to an aluminum plate measuring 99 mm x 99 mm x 0.8 mm to a coating thickness of 1 mm, and then dried at 23°C and 50% relative humidity for at least 7 days to prepare a test plate. The total heat release rate of the test plate over 20 minutes was determined using a cone calorimeter test in accordance with ISO 5660-1:2002. Flammability was evaluated based on the total heat release rate according to the following criteria. Note that "-" indicates that no evaluation was performed. ◎: 4.0MJ / m 2 below 〇:4.0MJ / m 2 Exceeds 5MJ / m 2 below △: 5.0MJ / m 2 Exceeds 6MJ / m 2 below ×:8.0MJ / m 2 Exceeds -: Not evaluated

[0102] <Painting workability> The paint was diluted with an appropriate amount of water and applied to a 300 mm square plasterboard using a trowel and a medium-grained mastic roller, and the workability was evaluated according to the following criteria. ◎: Paint can be applied evenly with a trowel or roller 〇: Trowel painting is possible, but roller painting is not possible (unevenness occurs) ×: Trowel and roller painting are not possible -: Not evaluated

[0103] <Combustibility of coating systems> A 99mm x 99mm x 0.8mm aluminum plate was coated with DNT's Mighty All-Purpose Water-Based Sealer White to a thickness of 20µm and dried for 2 hours at 23°C and 50% relative humidity. The paint described in Example 3 was then coated to a thickness of 1mm and dried at 23°C and 50% relative humidity for at least 1 day. Further, DNT's Ecocool Aqua F was applied at 2-hour intervals at 23°C and 50% relative humidity to a total thickness of 50µm. The test plate was then dried at 23°C and 50% relative humidity for 7 days to prepare a test plate. The total heat generation rate of the test plate over 20 minutes was determined using a cone calorimeter test in accordance with ISO 5660-1:2002. The resulting total heat generation rate was 6.65MJ / m. 2 It was.

[0104] [Table 1]

[0105] [Table 2]

Claims

1. A water-based coating composition comprising (A) a water-dispersed resin, (B) hollow particles, and (C) water, The thermal conductivity of the coating film formed from the water-based coating composition is 0.2 W / m K or less, and the total heat generation rate of a test plate formed from the water-based coating composition on an aluminum plate with dimensions of 99 ± 1.0 mm x 99 mm ± 1.0 x 0.8 mm and having a coating thickness of 1 mm is 8.0 MJ / m or less in a 20-minute cone calorimeter test. ２ is as follows: the (A) water-dispersible resin contains an acrylic water-dispersible resin and / or a silicone-modified acrylic resin, The (A) water-dispersible resin is contained in the coating film-forming components in an amount of 34.2 to 56.6 mass %; The water-based coating composition is characterized in that the hollow particles (B) are contained in the coating film-forming components in an amount of 70.0 to 90.0% by volume, and have a 50% particle size by volume of 20 to 70 μm.

2. 2. The aqueous coating composition according to claim 1, wherein the water-dispersible resin (A) comprises a silanol group-containing acrylic resin dispersion.

3. 3. The water-based coating composition according to claim 1, wherein a coating film formed from the water-based coating composition contains 30% by volume or more of (B) hollow particles having a size of 25 μm or more on a volume basis.

4. 3. The water-based coating composition according to claim 1, wherein the organic content in the coating film formed from the water-based coating composition is 70 wt % or less.

5. 3. The water-based coating composition according to claim 1, wherein the hollow particles (B) are inorganic hollow particles.

6. 3. The water-based coating composition according to claim 1, further comprising (D) an inorganic pigment.

7. A method for painting buildings, comprising the steps of: forming a primer layer on a substrate; applying the aqueous paint composition of claim 1 or claim 2 to the primer layer to form an intermediate coat layer; and further forming a top coat layer on the intermediate coat layer.

Images