HEAT-SHIELDING COMPOSITION, HEAT-SHIELDING MATERIAL, AND HOLLOW PARTICLES USED IN HEAT-SHIELDING COMPOSITION

Abstract

To provide a heat insulating composition and a heat insulating material with which an excellent heat insulating performance can be exhibited, and hollow particles used for the heat insulating composition.MEANS FOR SOLVING THE PROBLEM: A heat insulating composition includes hollow particles (A) with their outer shell portions containing a thermoplastic resin, and a base material component (B), wherein a ratio (r1 / r2) of inner diameter (r1) to outer diameter (r2) of the particles (A) is 0.7-0.999, an average particle diameter of the particles (A) is 0.1-50 μm, and a residual ratio of the particles (A) after immersion in methyl ethyl ketone for 24 hours is 50% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat-shielding composition, a heat-shielding material, and hollow particles used in the heat-shielding composition. [Background technology]

[0002] Heat-shielding properties are generally achieved by reflecting light in the wavelength range of 780 to 2100 nm. Heat-shielding materials can be applied to the roofs and exterior walls of buildings such as factories and houses, as well as the roofs and exterior walls of containers, refrigerated trucks, and storage sheds, to suppress the rise in internal temperature caused by light. In order to achieve heat-shielding properties, pigments such as titanium oxide are generally used, but some products also use inorganic particles such as glass beads to enhance the heat-shielding effect.

[0003] Patent Document 1 discloses a coating material containing hollow particles and a structure-retaining agent that maintains the arrangement of the hollow particles after a coating film is formed, and that by using hollow glass particles as the hollow particles, it is possible to reduce thermal conductivity and airborne sound, thereby improving heat insulation and sound insulation. However, when hollow glass particles are used, a large amount of hollow glass particles is required to exhibit a heat-shielding effect, which results in insufficient dispersibility of the hollow glass particles and poor coatability. As a result, it is necessary to add another additive or reduce the amount of hollow glass particles added, which results in the problem of being unable to exhibit sufficient heat-shielding performance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2017-186452 Summary of the Invention [Problem to be solved by the invention]

[0005] Thus, there has been no heat-shielding composition that can fully exhibit heat-shielding properties. An object of the present invention is to provide a heat-shielding composition and a heat-shielding material that can exhibit excellent heat-shielding performance, and hollow particles used in the heat-shielding composition. [Means for solving the problem]

[0006] As a result of extensive research, the present inventors have found that a heat-shielding composition containing specific hollow particles and a base component can solve the above problems, and have arrived at the present invention. That is, the present invention provides a heat-shielding composition comprising hollow particles (A) whose outer shell comprises a thermoplastic resin and a base component (B), wherein the ratio (r1 / r2) of the inner diameter (r1) to the outer diameter (r2) of the particles (A) is 0.7 to 0.999, the average particle size of the particles (A) is 0.1 to 50 μm, and the particle survival rate after immersion of the particles (A) in methyl ethyl ketone for 24 hours is 50% or more.

[0007] The heat-shielding composition of the present invention preferably satisfies at least one of the following requirements 1) to 3). 1) The thermoplastic resin is a polymer of a polymerizable component containing a monomer (C) having one polymerizable carbon-carbon double bond, the monomer (C) contains a nitrile-based monomer, and the content of the nitrile-based monomer is 30 parts by weight or more per 100 parts by weight of the monomer (C). 2) The content of the hollow particles (A) is 0.001 to 20 parts by weight per 100 parts by weight of the content of the base component (B). 3) A coating composition.

[0008] The heat-shielding material of the present invention is obtained by molding the above-mentioned heat-shielding composition.

[0009] The present invention also relates to hollow particles for use in a heat-shielding composition, the hollow particles having an outer shell comprising a thermoplastic resin, a ratio (r1 / r2) of inner diameter (r1) to outer diameter (r2) of 0.7 to 0.999, an average particle size of 0.1 to 50 μm, and a survival rate of 50% or more after immersion in methyl ethyl ketone for 24 hours.

[0010] The fine particle-coated hollow particles of the present invention contain the above hollow particles and fine particles, with the fine particles being attached to the surface of the outer shell of the hollow particles. [Effects of the Invention]

[0011] The heat-shielding composition of the present invention can exhibit excellent heat-shielding properties. The heat-shielding material of the present invention is obtained by molding the above-mentioned heat-shielding composition, and therefore has excellent heat-shielding performance. The hollow particles used in the heat-shielding composition of the present invention can provide a heat-shielding composition that can exhibit excellent heat-shielding performance. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic diagram showing an example of fine particle-coated hollow particles. [Figure 2] FIG. 1 is a schematic diagram of an expansion process section of a manufacturing apparatus for producing hollow particles by a dry thermal expansion method. [Figure 3] FIG. 1 is a schematic diagram of an apparatus for measuring the backside temperature of a test piece having a heat shield. DETAILED DESCRIPTION OF THE INVENTION

[0013] The heat-shielding composition of the present invention essentially contains hollow particles (A) and a base component (B). Each component constituting the heat-shielding composition will be described in detail below.

[0014] [Hollow particle (A)] The hollow particles (A) (hereinafter sometimes simply referred to as particles (A)) are an essential component of the heat-shielding composition of the present invention and are used in the heat-shielding composition. The particles (A) have an outer shell containing a thermoplastic resin and have a hollow portion corresponding to a cavity inside the particle. By forming the outer shell containing a thermoplastic resin, the particles (A) are lightweight and highly dispersible, and can exhibit excellent heat-shielding performance. Furthermore, the particles (A) preferably include an outer shell and a hollow portion surrounded by the outer shell. The particles (A) are (almost) spherical, and a familiar example of this shape is a soft tennis ball. The particles (A) may be expanded heat-expandable microspheres, which will be described later.

[0015] The outer shell of the particle (A) is surrounded by its outer and inner surfaces, has no edge, and has a continuous shape. The hollow portion of the particle (A) is (almost) spherical and is in contact with the inner surface of the outer shell. The hollow portion is basically filled with gas, and may be in a liquefied state. Usually, one large hollow portion is preferred, but there may be multiple hollow portions in the particle (A).

[0016] The ratio (r1 / r2) of the inner diameter (r1) to the outer diameter (r2) of the particles (A) is 0.7 to 0.999. If this ratio is less than 0.7, the heat-shielding performance exhibited will be reduced. On the other hand, if this ratio exceeds 0.999, the thickness of the outer shell of the particles (A) will be too thin, and the particles (A) will be crushed or deformed during the production of the heat-shielding composition or heat-shielding material. The upper limit of this ratio is preferably 0.99, more preferably 0.98, even more preferably 0.97, particularly preferably 0.95, and most preferably 0.94. On the other hand, the lower limit of this ratio is preferably 0.75, more preferably 0.80, and even more preferably 0.85. The ratio of the inner diameter (r1) to the outer diameter (r2) of the particle (A) is determined by the method described in the examples of the present invention.

[0017] The average particle size of the particles (A) is 0.1 to 50 μm. If the average particle size is less than 0.1 μm, the hollow particles will aggregate, resulting in poor dispersibility and a poorer heat-shielding performance. On the other hand, if the average particle size exceeds 50 μm, the infrared light reflection efficiency will decrease, resulting in a poorer heat-shielding performance. The upper limit of the average particle size is preferably 40 μm, more preferably 35 μm, even more preferably 30 μm, particularly preferably 25 μm, and most preferably 20 μm. On the other hand, the lower limit of the average particle size is preferably 0.3 μm, more preferably 0.5 μm, even more preferably 1 μm, and particularly preferably 2 μm. The average particle size of the particles (A) is determined by the method described in the examples of the present invention.

[0018] The ratio (D90 / D50) of the volume-based cumulative 90% particle size (D90) to the average particle size of the particles (A) is not particularly limited, but is preferably 1.1 to 6. When this ratio is 1.1 or more, dispersibility in the heat-shielding composition tends to be improved, and when it is 6 or less, unevenness in the resulting heat-shielding material tends to be reduced. The upper limit of this ratio is more preferably 5, even more preferably 4, and particularly preferably 3. On the other hand, the lower limit of this ratio is more preferably 1.2, even more preferably 1.3, and particularly preferably 1.4. The volume-based cumulative 90% particle diameter (D90) of the particles (A) is determined by the method described in the examples of the present invention.

[0019] The true specific gravity of the particles (A) is not particularly limited, but is preferably 0.003 to 0.6. When the true specific gravity is 0.003 or more, crushing and deformation of the particles (A) tend to be suppressed. On the other hand, when the true specific gravity is 0.6 or less, the heat-shielding performance exhibited tends to be improved. The upper limit of the true specific gravity is more preferably 0.4, even more preferably 0.3, particularly preferably 0.2, and most preferably 0.15. The lower limit of the true specific gravity is more preferably 0.005, even more preferably 0.01, and particularly preferably 0.03. The true specific gravity of the particles (A) is determined by the method described in the examples of the present invention.

[0020] The particle residual rate of particles (A) after immersion in methyl ethyl ketone for 24 hours (hereinafter simply referred to as particle residual rate) is 50% or more. If the particle residual rate is less than 50%, the strength of the thermoplastic resin forming the outer shell is low, and particles (A) may be crushed or deformed during the production of a heat-shielding composition or heat-shielding material. Furthermore, when used together with an organic solvent, particles (A) may swell significantly in the organic solvent, preventing the expression of sufficient heat-shielding performance. The particle residual rate is preferably 60 to 100%, more preferably 65 to 100%, even more preferably 70 to 100%, and particularly preferably 75 to 100%. The particle survival rate of particles (A) after immersion in methyl ethyl ketone for 24 hours is measured by the method described in the examples of the present invention.

[0021] The outer shell of the particles (A) contains a thermoplastic resin. The thermoplastic resin forming the outer shell of the particles (A) is not particularly limited, but is preferably a polymer of a polymerizable component that contains a monomer (C) having one polymerizable carbon-carbon double bond and may also contain a monomer (D) having at least two polymerizable carbon-carbon double bonds.

[0022] Examples of the monomer (C) contained in the polymerizable component include nitrile monomers such as acrylonitrile, methacrylonitrile, fumaronitrile, and maleonitrile; halogenated vinyl monomers such as vinyl chloride; halogenated vinylidene monomers such as vinylidene chloride; vinyl ester monomers such as vinyl acetate, vinyl propionate, and vinyl butyrate; unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, crotonic acid, and cinnamic acid, and maleic acid, itaconic acid, fumaric acid, citraconic acid, and chloromethyl ester monomers. Carboxyl group-containing monomers such as unsaturated dicarboxylic acids such as leic acid, anhydrides of unsaturated dicarboxylic acids, and unsaturated dicarboxylic acid monoesters such as monomethyl maleate, monoethyl maleate, monobutyl maleate, monomethyl fumarate, monoethyl fumarate, monomethyl itaconate, monoethyl itaconate, and monobutyl itaconate; methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (Meth)acrylic acid ester monomers such as methyl acrylate, stearyl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate; (meth)acrylamide monomers such as acrylamide, substituted acrylamide, methacrylamide, and substituted methacrylamide; and maleimide monomers such as N-phenylmaleimide and N-cyclohexylmaleimide. Examples of suitable monomers include styrene-based monomers such as styrene and α-methylstyrene; ethylenically unsaturated monoolefin-based monomers such as ethylene, propylene, and isobutylene; vinyl ether-based monomers such as vinyl methyl ether, vinyl ethyl ether, and vinyl isobutyl ether; vinyl ketone-based monomers such as vinyl methyl ketone; N-vinyl-based monomers such as N-vinylcarbazole and N-vinylpyrrolidone; vinylnaphthalene salts; and itaconate diesters such as dimethyl itaconate and dibutyl itaconate. Some or all of the carboxyl groups in the carboxyl-containing monomer may be neutralized during or after polymerization. These monomer components may be used alone or in combination. In the present invention, acrylic acid and methacrylic acid may be collectively referred to as (meth)acrylic acid, and (meth)acrylic means acrylic or methacrylic, and (meth)acrylate means acrylate or methacrylate.

[0023] It is preferable for the polymerizable component to contain a nitrile monomer as monomer (C), since this improves the density and solvent resistance of the thermoplastic resin forming the outer shell. The content of the nitrile monomer is not particularly limited, but is preferably 30 parts by weight or more per 100 parts by weight of monomer (C). The upper limit of the content is preferably 100 parts by weight, more preferably 99.7 parts by weight, even more preferably 99.5 parts by weight, particularly preferably 99 parts by weight, and most preferably 98 parts by weight. Meanwhile, the lower limit of the content is more preferably 35 parts by weight, even more preferably 40 parts by weight, particularly preferably 45 parts by weight, and most preferably 50 parts by weight.

[0024] When the monomer (C) contains a nitrile-based monomer, the nitrile-based monomer preferably contains acrylonitrile and / or methacrylonitrile, and preferably contains acrylonitrile as an essential component, in order to improve the rigidity of the thermoplastic resin forming the outer shell. When the nitrile monomer contains acrylonitrile, the amount thereof is not particularly limited, but is preferably 30 to 100 parts by weight per 100 parts by weight of the nitrile monomer. The upper limit of the content is more preferably 95 parts by weight, even more preferably 90 parts by weight, particularly preferably 80 parts by weight, and most preferably 70 parts by weight. On the other hand, the lower limit of the content is more preferably 35 parts by weight, even more preferably 40 parts by weight, particularly preferably 45 parts by weight, and most preferably 50 parts by weight. When the nitrile monomer contains methacrylonitrile, the amount thereof is not particularly limited, but is preferably 5 to 100 parts by weight relative to 100 parts by weight of the nitrile monomer. The upper limit of the content is more preferably 70 parts by weight, even more preferably 65 parts by weight, particularly preferably 60 parts by weight, and most preferably 50 parts by weight. On the other hand, the lower limit of the content is more preferably 10 parts by weight, even more preferably 20 parts by weight, and particularly preferably 30 parts by weight.

[0025] When the nitrile monomer contains acrylonitrile (AN) and methacrylonitrile (MAN), the weight ratio of AN to MAN (AN / MAN) is not particularly limited, but is preferably 30 / 70 to 99 / 1. The upper limit of this weight ratio is more preferably 90 / 10, even more preferably 87 / 13, and particularly preferably 80 / 20. On the other hand, the lower limit of this weight ratio is more preferably 40 / 60, even more preferably 50 / 50, particularly preferably 55 / 45, and most preferably 60 / 40.

[0026] If the monomer (C) contains a (meth)acrylic acid ester, the glass transition temperature of the thermoplastic resin forming the outer shell can be adjusted, and the production conditions for the hollow particles (A) can be adjusted, which is preferable. When the monomer (C) contains a (meth)acrylic acid ester, the amount thereof is not particularly limited, but is 0.2 to 70 parts by weight per 100 parts by weight of the monomer (C). The upper limit of the content is more preferably 60 parts by weight, even more preferably 50 parts by weight, particularly preferably 35 parts by weight, and most preferably 20 parts by weight. On the other hand, the lower limit of the content is more preferably 0.5 parts by weight, even more preferably 0.7 parts by weight, and particularly preferably 1 part by weight.

[0027] Monomer (C) preferably contains a vinylidene halide monomer, since this improves the gas barrier properties of the thermoplastic resin forming the outer shell. When the monomer (C) contains a vinylidene halide monomer, the amount thereof is not particularly limited, but is preferably 0.2 to 70 parts by weight relative to 100 parts by weight of the monomer (C). The upper limit of the content is more preferably 60 parts by weight, even more preferably 50 parts by weight, particularly preferably 35 parts, and most preferably 20 parts. On the other hand, the lower limit of the weight ratio is more preferably 0.5 parts by weight, even more preferably 0.7 parts by weight, and particularly preferably 1 part by weight.

[0028] It is preferable that the monomer (C) contains a carboxyl group-containing monomer, since this improves the heat resistance of the thermoplastic resin forming the outer shell. The content of the carboxyl group-containing monomer is not particularly limited, but is preferably 0 to 80 parts by weight relative to 100 parts by weight of the monomer (C). The upper limit of the content is more preferably 70 parts by weight, even more preferably 60 parts by weight, particularly preferably 50 parts by weight, and most preferably 45 parts by weight. On the other hand, the lower limit of the content is more preferably 5 parts by weight, even more preferably 10 parts by weight, particularly preferably 15 parts by weight, and most preferably 20 parts by weight.

[0029] As described above, the polymerizable component may contain the monomer (D), which is preferable in that the heat resistance and solvent resistance of the thermoplastic resin forming the outer shell are improved. Examples of the monomer (D) include aromatic divinyl compounds such as divinylbenzene; allyl methacrylate, triacrylformal, triallyl isocyanate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polytetramethylene glycol diacrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, and 1,9-nonanediol. Examples of the monomer (D) include polyfunctional (meth)acrylate compounds such as di(meth)acrylate, PEG#200 di(meth)acrylate, PEG#400 di(meth)acrylate, PEG#600 di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, 2-butyl-2-ethyl-1,3-propanediol diacrylate, and tricyclodecane dimethanol di(meth)acrylate. These monomers (D) may be used alone or in combination of two or more.

[0030] The polymerizable component does not necessarily contain monomer (D), but when the polymerizable component contains monomer (D), the amount thereof is not particularly limited, but is preferably 0.01 to 10 parts by weight per 100 parts by weight of monomer (C). The upper limit of the content is more preferably 0.1 parts by weight, even more preferably 0.3 parts by weight, and particularly preferably 0.5 parts by weight. Meanwhile, the lower limit of the content is more preferably 6 parts by weight, even more preferably 3.5 parts by weight, particularly preferably 1.6 parts by weight, and most preferably 1.1 parts by weight.

[0031] The particles (A) may contain a component that vaporizes when heated. If a component that vaporizes when heated is contained, the pressure inside the particles (A) is increased, the pressure resistance of the particles (A) is improved, and the particles (A) can maintain their shape, which is preferable in that the heat-shielding performance provided is improved. Examples of components that vaporize upon heating include hydrocarbons having 3 to 13 carbon atoms, such as propane, (iso)butane, (iso)pentane, (iso)hexane, (iso)heptane, (iso)octane, (iso)nonane, (iso)decane, (iso)undecane, (iso)dodecane, and (iso)tridecane; hydrocarbons having more than 13 but not more than 20 carbon atoms, such as (iso)hexadecane and (iso)eicosane; and petroleum fractions such as pseudocumene, petroleum ether, and normal paraffins and isoparaffins having an initial boiling point of 150 to 260°C and / or a distillation range of 70 to 360°C. Examples of the component include hydrocarbons containing 1 to 12 carbon atoms; halides of hydrocarbons containing 1 to 12 carbon atoms such as methyl chloride, methylene chloride, chloroform, and carbon tetrachloride; fluorine-containing compounds such as hydrofluoroethers; silanes having an alkyl group containing 1 to 5 carbon atoms such as tetramethylsilane, trimethylethylsilane, trimethylisopropylsilane, and trimethyl-n-propylsilane; and compounds that generate gas upon thermal decomposition by heating, such as azodicarbonamide, N,N'-dinitrosopentamethylenetetramine, and 4,4'-oxybis(benzenesulfonylhydrazide). The component may be composed of one type of compound or a mixture of two or more types of compounds. The component may be linear, branched, or alicyclic, with aliphatic compounds being preferred. The component that vaporizes upon heating is not particularly limited, but it is preferable to include a compound having a boiling point of 30° C. or less, since this further improves the pressure resistance of the particles (A). In addition, the compound having a boiling point of 30° C. or less is preferably a hydrocarbon having 3 to 5 carbon atoms.

[0032] The content of the component that vaporizes upon heating contained in the particles (A) is not particularly limited, but is preferably 0.5% by weight or more based on the total weight of the particles (A). A content of 0.5% by weight or more tends to provide sufficient pressure resistance. The upper limit of the content is preferably 20% by weight, more preferably 15% by weight, even more preferably 12% by weight, and particularly preferably 10% by weight. Meanwhile, the lower limit of the content is more preferably 1% by weight, even more preferably 1.5% by weight, and particularly preferably 2% by weight. The content of the component that vaporizes when heated in the particles (A) is determined by the method described in the examples of the present invention.

[0033] [Method for producing hollow particles (A)] The hollow particles (A) contained in the heat-shielding composition of the present invention can be produced, for example, by a method comprising Step 1 (expansion step) of thermally expanding heat-expandable microspheres, each of which has a shell containing a thermoplastic resin and a blowing agent encapsulated therein and vaporized by heating. The heat-expandable microspheres must be produced prior to the expansion step, and examples of the method for producing such heat-expandable microspheres include a method comprising Step 2 (polymerization step) of polymerizing the polymerizable component using a polymerization initiator in an aqueous dispersion medium in which an oily mixture containing the polymerizable component and the blowing agent has been dispersed. Therefore, the particles (A) can be produced through a polymerization step and an expansion step in this order. The particles (A) contained in the heat-shielding composition of the present invention are preferably produced through a step of thermally expanding heat-expandable microspheres, as in the expansion step described above, in that the particles (A) can be obtained efficiently.

[0034] (Polymerization process) The foaming agent may be any agent that vaporizes when heated, and the component contained in the particles (A) described above that vaporizes when heated may be used. Furthermore, when the particles (A) contained in the heat-shielding composition of the present invention are expanded bodies obtained by expanding heat-expandable microspheres, the component contained in the particles (A) that vaporizes upon heating includes the blowing agent contained in the heat-expandable microspheres.

[0035] In the polymerization step, the above-mentioned polymerizable components are polymerized to form a thermoplastic resin that forms the outer shell of the heat-expandable microspheres. In the polymerization step, the polymerizable components are preferably polymerized in the presence of a polymerization initiator, which is preferably contained in the oily mixture together with the polymerizable components and the blowing agent. The polymerization initiator is not particularly limited, but examples thereof include peroxides such as peroxydicarbonate, peroxyester, and diacyl peroxide; azo compounds such as azonitrile, azoester, azoamide, azoalkyl, and polymeric azo initiator. These polymerization initiators may be used alone or in combination of two or more. Note that the polymerization initiator is preferably an oil-soluble polymerization initiator that is soluble in the polymerizable component. The amount of the polymerization initiator to be added is not particularly limited, but is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 8 parts by weight, and even more preferably 0.2 to 5 parts by weight, per 100 parts by weight of the polymerizable component. In the polymerization step, the oily mixture may further contain a chain transfer agent or the like.

[0036] The aqueous dispersion medium is a medium containing water, such as ion-exchanged water, as a main component for dispersing the oily mixture, and may further contain alcohols, such as methanol, ethanol, and propanol, or hydrophilic organic solvents, such as acetone. The term "hydrophilic" in the present invention means a state in which the aqueous dispersion medium can be arbitrarily mixed with water. The amount of the aqueous dispersion medium used is not particularly limited, but it is preferable to use 100 to 1,000 parts by weight of the aqueous dispersion medium per 100 parts by weight of the polymerizable component.

[0037] The aqueous dispersion medium may further contain an electrolyte. Examples of the electrolyte include sodium chloride, magnesium chloride, calcium chloride, sodium sulfate, magnesium sulfate, ammonium sulfate, and sodium carbonate. These electrolytes may be used alone or in combination of two or more. The content of the electrolyte is not particularly limited, but it is preferably 0.1 to 50 parts by weight per 100 parts by weight of the aqueous dispersion medium.

[0038] The aqueous dispersion medium may contain at least one water-soluble compound selected from the group consisting of water-soluble 1,1-substituted compounds having a structure in which a hydrophilic functional group selected from a hydroxyl group, a carboxylic acid (salt) group, and a phosphonic acid (salt) group and a heteroatom are bonded to the same carbon atom, polyalkyleneimines having a structure in which an alkyl group substituted with a hydrophilic functional group selected from a carboxylic acid (salt) group and a phosphonic acid (salt) group is bonded to a nitrogen atom, water-soluble ascorbic acids, water-soluble polyphenols, water-soluble B vitamins, potassium dichromate, alkali metal nitrites, metal (III) halides, boric acid, and water-soluble phosphonic acids (salts). In the present invention, water solubility refers to a state in which 1 g or more of the compound dissolves in 100 g of water. The amount of the water-soluble compound contained in the aqueous dispersion medium is not particularly limited, but is preferably 0.0001 to 1.0 part by weight, more preferably 0.0003 to 0.1 part by weight, and even more preferably 0.001 to 0.05 part by weight, relative to 100 parts by weight of the polymerizable component.

[0039] The aqueous dispersion medium may contain a dispersion stabilizer or a dispersion stabilization aid in addition to the electrolyte and the water-soluble compound. The dispersion stabilizer is not particularly limited, but examples thereof include tribasic calcium phosphate, magnesium pyrophosphate obtained by a metathesis method, calcium pyrophosphate, colloidal silica, alumina sol, magnesium hydroxide, etc. These dispersion stabilizers may be used alone or in combination of two or more. The amount of the dispersion stabilizer to be added is preferably 0.05 to 100 parts by weight, more preferably 0.2 to 70 parts by weight, based on 100 parts by weight of the polymerizable component. The dispersion stabilization aid is not particularly limited, and examples thereof include surfactants such as polymer-type dispersion stabilization aids, cationic surfactants, anionic surfactants, zwitterionic surfactants, nonionic surfactants, etc. These dispersion stabilization aids may be used alone or in combination of two or more.

[0040] The aqueous dispersion medium is prepared, for example, by blending water (ion-exchanged water) with an electrolyte, a water-soluble compound, a dispersion stabilizer, a dispersion stabilization assistant, etc., as necessary. The pH of the aqueous dispersion medium during polymerization is determined appropriately depending on the types of the water-soluble compound, dispersion stabilizer, and dispersion stabilization assistant. In the polymerization step, the polymerization may be carried out in the presence of sodium hydroxide or sodium hydroxide and zinc chloride.

[0041] In the polymerization process, the oil mixture is added to an aqueous dispersion medium so as to prepare spherical oil droplets of a predetermined particle size. Suspend and disperse. Examples of methods for suspending and dispersing an oily mixture include a method of stirring using a homomixer (e.g., manufactured by Primix Corporation) or the like, a method using a static dispersing device such as a static mixer (e.g., manufactured by Noritake Engineering Co., Ltd.), a membrane suspension method, an ultrasonic dispersion method, and other common dispersion methods. The suspension polymerization is then initiated by heating the dispersion in which the oily mixture is dispersed as oil globules in the aqueous dispersion medium. During the polymerization reaction, the dispersion is preferably stirred, and the stirring may be gentle enough to prevent the floating of the monomers and the settling of the heat-expandable microspheres after polymerization.

[0042] The polymerization temperature can be freely set depending on the type of polymerization initiator, but is preferably controlled within a range of 30 to 100°C, more preferably 40 to 90°C. The reaction temperature is preferably maintained for about 1 to 20 hours. The initial polymerization pressure is not particularly limited, but is preferably in the range of 0 to 5 MPa, more preferably 0.2 to 3 MPa, in gauge pressure.

[0043] The obtained slurry is filtered using a centrifuge, a pressure press, a vacuum dehydrator, or the like to produce a cake-like substance with a moisture content of 10 to 50% by weight, preferably 15 to 45% by weight, and more preferably 20 to 40% by weight. The cake-like substance is then dried using a tray dryer, an indirect heating dryer, a fluidized bed dryer, a vacuum dryer, a vibration dryer, a flash dryer, or the like to produce a dry powder with a moisture content of 5% by weight or less, preferably 3% by weight or less, and more preferably 1% by weight or less. Alternatively, the slurry may be dried using a spray dryer, fluidized bed dryer, or the like to obtain a dry powder.

[0044] In this way, heat-expandable microspheres are obtained which comprise a shell containing a thermoplastic resin and a blowing agent encapsulated therein and vaporized by heating. The average particle size of the heat-expandable microspheres obtained by the polymerization step is not particularly limited, but is preferably 0.05 to 25 μm, more preferably 0.1 to 20 μm, even more preferably 0.3 to 15 μm, particularly preferably 0.5 to 12 μm, and most preferably 0.7 to 12 μm. The true specific gravity of the heat-expandable microspheres obtained by the polymerization step is preferably 0.97 to 1.30, more preferably 1.05 to 1.20. When the true specific gravity of the heat-expandable microspheres is within the above range, the particles (A) tend to be obtained efficiently.

[0045] (Expansion process) The expansion step is not particularly limited as long as it is a step of thermally expanding the heat-expandable microspheres, and may be either a dry thermal expansion method or a wet thermal expansion method. The dry thermal expansion method is described in JP-A-2006-213930, particularly the internal injection method. The wet thermal expansion method is described in JP-A-62-201231. The temperature at which the heat-expandable microspheres are heated and expanded is preferably 80 to 450°C.

[0046] When the particles (A) are expanded heat-expandable microspheres, it is preferable that the particles (A) have a residual expansion capacity in terms of pressure resistance. The residual expansion capacity of the particles (A) means the property of the hollow particles to further expand (re-expand) when heated. The expansion capacity of the hollow particles is not particularly limited, but is preferably 1 to 80%. A capacity of 1% or more tends to improve pressure resistance, while a capacity of 80% or less tends to improve the heat-shielding performance. The upper limit of the capacity of the hollow particles is more preferably 75%, even more preferably 70%, and particularly preferably 65%. The lower limit of the capacity of the hollow particles is more preferably 5%, even more preferably 10%, and particularly preferably 15%. The expansion capacity of unexpanded heat-expandable microspheres exceeds approximately 95%. The expansion capacity ratio indicates the degree of expansion of hollow particles at maximum re-expansion, and is calculated using the following formula (1) by measuring the true specific gravity (d1) of the hollow particles and the true specific gravity (d2) of the hollow particles at maximum re-expansion. Expansion capacity rate (%) = (1-d2 / d1) × 100 (1)

[0047] When the particle (A) has a residual expansion capacity, the re-expansion starting temperature (T S2 ) It is preferable that the particle (A) has a re-expansion starting temperature (T S2 ) is not particularly limited, but is preferably 60 to 210°C. S2 When the re-expansion temperature is 70°C or higher, the heat-shielding performance tends to be improved, and when the re-expansion temperature is 180°C or lower, the particles (A) tend to have sufficient pressure resistance. The upper limit of the re-expansion temperature is more preferably 150°C, even more preferably 130°C, and particularly preferably 120°C. On the other hand, the lower limit of the re-expansion temperature is more preferably 75°C, even more preferably 80°C, and particularly preferably 85°C. The re-expansion temperature (T S2 ) is according to the method described in the examples of the present invention.

[0048] When particle (A) has a residual expansion capacity, the maximum re-expansion temperature (T max2 ) It is preferable that the particle (A) has a maximum re-expansion temperature (T max2 ) is not particularly limited, but is preferably 90 to 200°C. max2When the re-expansion temperature is 90°C or higher, the heat-shielding performance tends to be improved, and when the re-expansion temperature is 200°C or lower, the particles (A) tend to have sufficient pressure resistance. The upper limit of the maximum re-expansion temperature is more preferably 150°C, and even more preferably 130°C. On the other hand, the lower limit of the maximum re-expansion temperature is more preferably 100°C, even more preferably 105°C, and particularly preferably 110°C. The maximum re-expansion temperature (T max2 ) is according to the method described in the examples of the present invention.

[0049] [Hollow particles with fine particles attached] The heat-shielding composition may be produced using microparticle-coated hollow particles. The microparticle-coated hollow particles include the hollow particles (hollow particles (A)) described above and microparticles, with the microparticles adhering to the outer surface of the outer shell of the hollow particles, as shown in FIG. 1, for example. "Adhering" here means that the microparticles (4 and 5) may simply be adsorbed onto the outer surface of the outer shell (2) of the hollow particle (4), or may mean that the thermoplastic resin forming the outer shell near the outer surface is softened or melted by heating, causing the microparticles to sink into the outer surface of the outer shell of the hollow particle and become fixed thereto (5). The particle shape of the microparticles may be either irregular or spherical.

[0050] Various types of fine particles can be used, and may be made of either inorganic or organic materials. The shape of the fine particles may be spherical, needle-like, or plate-like. The inorganic substance constituting the fine particles is not particularly limited, but examples thereof include wollastonite, sericite, kaolin, mica, clay, talc, bentonite, alumina silicate, pyrophyllite, montmorillonite, calcium silicate, calcium carbonate, magnesium carbonate, dolomite, calcium sulfate, barium sulfate, glass flakes, boron nitride, silicon carbide, silica, alumina, mica, titanium dioxide, zinc oxide, magnesium oxide, zinc oxide, hydrosaltite, carbon black, molybdenum disulfide, tungsten disulfide, ceramic beads, glass beads, quartz beads, and glass microballoons. As the inorganic substance constituting the fine particles, a pigment as described below may be used.

[0051] The organic substance constituting the microparticles is not particularly limited, but examples thereof include sodium carboxymethylcellulose, hydroxyethylcellulose, methylcellulose, ethylcellulose, nitrocellulose, hydroxypropylcellulose, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, sodium polyacrylate, carboxyvinyl polymer, polyvinyl methyl ether, magnesium stearate, calcium stearate, zinc stearate, polyethylene wax, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, hydrogenated castor oil, (meth)acrylic resin, polyamide resin, silicone resin, urethane resin, polyethylene resin, polypropylene resin, and fluorine-based resin. The inorganic or organic material constituting the fine particles may be treated with a surface treatment agent such as a silane coupling agent, paraffin wax, fatty acid, resin acid, urethane compound, or fatty acid ester, or may be untreated.

[0052] The average particle size of the fine particles is not particularly limited, but is preferably 0.001 to 30 μm, more preferably 0.005 to 25 μm, and particularly preferably 0.01 to 20 μm. The average particle size is the cumulative 50% particle size on a volume basis measured by laser diffraction. The ratio of the average particle size of the fine particles to the average particle size of the hollow particles (average particle size of the fine particles / average particle size of the hollow particles) is not particularly limited, but is preferably 1 or less, more preferably 0.1 or less, and even more preferably 0.05 or less, in terms of the adhesion of the fine particles to the surfaces of the hollow particles.

[0053] The weight percentage of the fine particles in the total fine particle-coated hollow particles is not particularly limited, but is preferably 95% by weight or less, more preferably 90% by weight or less, particularly preferably 85% by weight or less, and most preferably 80% by weight or less. If the weight percentage exceeds 95% by weight, the amount of fine particle-coated hollow particles added when preparing a composition using the fine particle-coated hollow particles becomes large, which may be uneconomical. The lower limit of the weight percentage of the fine particles is preferably 10% by weight, more preferably 20% by weight, particularly preferably 30% by weight, and most preferably 40% by weight.

[0054] The true specific gravity of the fine particle-coated hollow particles is not particularly limited, but is preferably 0.01 to 0.6. When the true specific gravity is 0.01 or more, crushing and deformation of the fine particle-coated hollow particles tend to be suppressed. On the other hand, when the true specific gravity is 0.6 or less, the heat-shielding performance exhibited tends to be improved. The upper limit of the true specific gravity is more preferably 0.5, even more preferably 0.4, particularly preferably 0.3, and most preferably 0.20. On the other hand, the lower limit of the true specific gravity is more preferably 0.03, even more preferably 0.05, particularly preferably 0.07, and most preferably 0.1.

[0055] The microparticle-coated hollow particles can be obtained, for example, by heating and expanding microparticle-coated heat-expandable microspheres. A preferred method for producing microparticle-coated hollow particles includes a step of mixing heat-expandable microspheres with microparticles (mixing step), and a step of heating the mixture obtained in the mixing step to a temperature above the softening point of the thermoplastic resin forming the outer shell of the heat-expandable microspheres to expand the heat-expandable microspheres and to cause microparticles to adhere to the outer surfaces of the resulting hollow particles (adhesion step).

[0056] (Mixing process) The mixing step is a step of mixing the heat-expandable microspheres with fine particles. The weight ratio of the fine particles to the total weight of the heat-expandable microspheres and fine particles in the mixing step is not particularly limited, but is preferably 95% by weight or less, more preferably 90% by weight or less, particularly preferably 85% by weight or less, and most preferably 80% by weight or less. When this weight ratio is 95% by weight or less, the obtained fine particle-coated hollow particles tend to be lightweight and have a sufficient effect of reducing the specific gravity. The lower limit of this weight ratio is preferably 5% by weight, more preferably 10% by weight, particularly preferably 20% by weight, and most preferably 30% by weight.

[0057] The device used to mix the heat-expandable microspheres and fine particles in the mixing step is not particularly limited, and can be a device equipped with a very simple mechanism such as a container and a stirring blade. Alternatively, a general powder mixer capable of shaking or stirring may also be used. Examples of powder mixers include ribbon mixers, vertical screw mixers, etc. In addition, more efficient and multifunctional powder mixers that have recently been developed by combining a stirring device, such as Super Mixer (manufactured by Kawata Co., Ltd.) and High Speed ​​Mixer (manufactured by Fukae Co., Ltd.), New Gram Machine (manufactured by Seishin Enterprise Co., Ltd.), and SV Mixer (manufactured by Kobelco Eco Solutions Co., Ltd.), may also be used.

[0058] (Attachment process) The adhering step is a step in which the mixture obtained in the mixing step described above is heated to a temperature above the softening point of the thermoplastic resin forming the outer shell of the heat-expandable microspheres. In this step, the heat-expandable microspheres are expanded and fine particles are adhered to the outer surface of the outer shell of the resulting hollow particles. Heating can be carried out using a general contact heat transfer or direct heating type mixing dryer. There are no particular limitations on the functions of the mixing dryer, but it is preferable that it has the ability to adjust the temperature, disperse and mix the raw materials, and, in some cases, a pressure reducing device or cooling device to accelerate drying. Examples of devices used for heating include a Lödige Mixer (manufactured by Matsubo Corporation) and a Solid Air (Hosokawa Micron Corporation). The heating temperature condition depends on the type of heat-expandable microspheres, but is preferably set to the optimum expansion temperature, preferably 70 to 250°C, more preferably 80 to 230°C, and even more preferably 90 to 220°C.

[0059] Even when the microparticle-coated hollow particles are obtained by expanding heat-expandable microspheres, it is preferable that the hollow particles constituting the microparticle-coated hollow particles have expansion capacity, as explained above. When the fine-particle-coated hollow particles have expansion capacity, the expansion capacity ratio of the constituent hollow particles is preferably in the same range as the expansion capacity ratio of the particles (A) described above. Furthermore, when the fine-particle-coated hollow particles have expansion capacity, the re-expansion start temperature and maximum re-expansion temperature of the fine-particle-coated hollow particles are preferably in the same range as the re-expansion start temperature and maximum re-expansion temperature of the particles (A) described above.

[0060] [Base material component (B)] Base component (B) (hereinafter sometimes simply referred to as component (B)) is a component that is essential to the heat-shielding composition. Component (B) is not particularly limited and can be selected appropriately depending on the form and application of the heat-shielding composition. Examples of component (B) include rubbers such as natural rubber, isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), chloroprene rubber (CR), nitrile rubber (NBR), butyl rubber, silicone rubber, acrylic rubber, urethane rubber, fluororubber, and ethylene-propylene-diene rubber (EPDM); thermosetting resins such as epoxy resin, melamine resin, phenolic resin, unsaturated polyester resin, and polyurethane; resin waxes such as polyethylene wax; ethylene-vinyl acetate copolymer (EVA), polyethylene, modified polyethylene, polypropylene, modified polypropylene, modified polyolefin, acrylic resin, and thermoplastic polyurethane. Examples of suitable resins include thermoplastic resins such as styrene, acrylonitrile-styrene copolymers (AS resins), acrylonitrile-butadiene-styrene copolymers (ABS resins), polystyrene (PS), polylactic acid (PLA), polybutylene succinate (PBS), polyhydroxyalkanoates (PHA), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyacetal (POM); ionomer resins such as ethylene-based ionomers, urethane-based ionomers, and styrene-based ionomers; thermoplastic elastomers such as olefin-based elastomers, styrene-based elastomers, and polyester-based elastomers; and bioplastics such as starch resins. Examples of suitable resins also include plastisols containing rubbers such as vinyl chloride resins, acrylic resins, polyurethane resins, polyester resins, melamine resins, epoxy resins, ethylene-vinyl acetate copolymers (EVA), natural rubber, and styrene-based rubber, and plasticizers; and resin-containing liquids such as latex and resin emulsions containing these resins in a liquid dispersion medium. Among these components (B), rubbers, thermoplastic resins, and resin-containing liquids are preferred in terms of moldability of the heat shield material.

[0061] [Other ingredients] In addition to the particles (A) and component (B), the heat-shielding composition of the present invention may contain other components, such as pigments, inorganic fillers, organic fillers, plasticizers, stabilizers, lubricants, rheology modifiers, surfactants, and antioxidants, as necessary. Examples of pigments include white pigments such as titanium oxide; black pigments such as Paliogen (registered trademark) Black L 0086 (manufactured by BASF) and Sicopal (registered trademark) Black 0095 (manufactured by BASF); blue pigments such as Fastogen (registered trademark) Blue 5485K (manufactured by DIC Corporation), Fastogen (registered trademark) Blue RSE (manufactured by DIC Corporation), and Cyanine Blue 5240KB (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.); and red pigments such as Fastogen (registered trademark) Super Magenta RH (manufactured by DIC Corporation), Fastogen (registered trademark) Red 7100Y (manufactured by DIC Corporation), and Rubicron Red 400RG (manufactured by DIC Corporation). Examples of inorganic fillers include magnesium hydroxide, aluminum hydroxide, calcium hydroxide, alumina, titanium oxide, magnesium oxide, calcium oxide, zinc oxide, antimony trioxide, antimony pentoxide, calcium sulfate, barium sulfate, potassium carbonate, magnesium carbonate, aluminum silicate, calcium silicate, magnesium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, calcium aluminum silicate, wollastonite, and glass beads.

[0062] Examples of organic fillers include cellulosic fibers such as cotton fiber, hemp fiber, and kenaf fiber; cellulosic powders such as paper powder, wood powder, bamboo powder, rice husk powder, and fruit husk powder; and starch. Examples of the plasticizer include phthalates, adipates, sebacates, azelates, phosphates, trimellitates, polyester-based polymer plasticizers, and epoxy-based plasticizers such as epoxidized soybean oil and epoxidized linseed oil.

[0063] Examples of lubricants include metal soaps such as calcium stearate, magnesium stearate, barium stearate, lead stearate, zinc stearate, calcium laurate, barium laurate, zinc laurate, and calcium ricinoleate; hydrocarbon waxes such as paraffin wax and liquid paraffin; amide waxes such as stearic acid amide, oleic acid amide, erucic acid amide, methylene bisstearic acid amide, and ethylene bisstearic acid amide; ester waxes such as stearic acid monoglyceride, stearyl stearate, and butyl stearate; fatty acid waxes such as stearic acid; and higher alcohol waxes such as stearyl alcohol.

[0064] Examples of rheology modifiers include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyacrylic acid, polyethylene glycol, polyethylene oxide, polyoxyethylene-polypropylene block polymers, polyalkylene glycol derivatives, polyvinyl alcohol, ethylene-modified polyvinyl alcohol, polyvinylpyrrolidone, gum arabic, guar gum, xanthan gum, gelatin, corn starch, polyacrylamide, polyethyleneimine, polynaphthalene sulfonate, polycarboxylic acid copolymers, vinyl alcohol copolymers, and vinylpyrrolidone copolymers. Examples of surfactants include anionic surfactants and nonionic surfactants. Examples of antioxidants include phenolic antioxidants such as n-octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, and phosphorus-based antioxidants such as tris(2,4-di-t-butylphenyl)phosphite.

[0065] The heat-shielding composition of the present invention can be prepared by mixing hollow particles (A), a base component (B), and, if necessary, other components. Alternatively, a heat-shielding composition can be prepared by mixing the hollow particles (A) with a base component (B) to obtain a composition, and then mixing the composition with another base component (B).

[0066] [Heat-shielding composition and its manufacturing method] The heat-shielding composition of the present invention essentially contains the hollow particles (A) described above and the base component (B) described above, and by molding it, a heat-shielding material with excellent heat-shielding performance can be obtained. The heat-shielding composition of the present invention is preferably a coating composition, since this allows for more efficient production of a heat-shielding material. Furthermore, the heat-shielding composition of the present invention is preferably in the form of a liquid or paste composition.

[0067] In the heat-shielding composition of the present invention, the content of particles (A) is not particularly limited, but is preferably 0.001 to 20 parts by weight per 100 parts by weight of component (B). When the content is 0.001 part by weight or more, the heat-shielding performance that can be exhibited tends to be improved. On the other hand, when the content is 20 parts by weight or less, the physical properties of component (B) tend to be more efficiently maintained. The upper limit of the content is more preferably 15 parts by weight, even more preferably 12 parts by weight, and particularly preferably 10 parts by weight. On the other hand, the lower limit of the content is more preferably 0.01 part by weight, even more preferably 0.1 part by weight, particularly preferably 0.5 parts by weight, and most preferably 1 part by weight.

[0068] The method for producing the heat-shielding composition of the present invention is not particularly limited, and any conventionally known method may be used, such as a method of mixing using a mixer such as a Disper mixer, a homomixer, a static mixer, a Henschel mixer, a tumbler mixer, a planetary mixer, a mixer, a single-screw kneader, a twin-screw kneader, or a multi-screw kneader.

[0069] [Heat shielding material and its manufacturing method] The heat-shielding material of the present invention is obtained by molding the heat-shielding composition described above and has excellent heat-shielding properties. The heat-shielding material of the present invention may be in the form of a coating film, a film, a sheet, or the like, and can be used for roofs and exteriors of buildings, roadbeds of asphalt roads, and the like.

[0070] When the heat shielding material of the present invention has a layer containing particles (A), the thickness of the layer is not particularly limited, but is preferably 50 to 1000 μm. A thickness of 50 μm or more tends to provide good heat shielding performance, while a thickness of 1000 μm or less tends to improve economic efficiency. The heat shield material of the present invention may consist of only a layer having particles (A), or may have other layers such as a protective layer in addition to the layer having particles (A).

[0071] The specific gravity of the heat shielding material of the present invention is not particularly limited, but is preferably 0.4 to 1.0, since the heat shielding material has uniform performance and good heat shielding performance. The upper limit of the specific gravity is more preferably 0.9, even more preferably 0.8, and particularly preferably 0.7. On the other hand, the lower limit of the specific gravity is more preferably 0.5.

[0072] The heat-shielding material of the present invention can be produced by, for example, coating methods such as spraying, flow heat-shielding, roll coating, bar coating, brush coating, dip heat-shielding, spin heat-shielding, screen printing, casting, gravure printing, and flexographic printing; extrusion molding; injection molding; calendar molding; inflation molding; blow molding; kneading molding; compression molding; vacuum molding; and thermoforming. When the heat-shielding material is formed by the coating method, drying may be carried out after coating, and after drying, further heat treatment or ultraviolet irradiation, preferably at 100°C or below, may be carried out to an extent that does not impair the performance of the heat-shielding material. [Example]

[0073] Examples of the present invention will be specifically described below. However, the present invention is not limited to these examples. In the following examples and comparative examples, unless otherwise specified, "%" means "% by weight" and "parts" means "parts by weight." The heat-expandable microspheres, hollow particles, and microparticle-coated hollow particles used below, as well as the heat-shielding compositions and heat-shielding materials given in the Examples and Comparative Examples, were measured for physical properties and evaluated for performance in the following manner. Hereinafter, heat-expandable microspheres will sometimes be referred to as "microspheres" for simplicity. Production Example A7 is a Reference Production Example, and Example 9 is a Reference Example.

[0074] [Measurement of the average particle size of heat-expandable microspheres] A laser diffraction scattering particle size distribution analyzer (Microtrac ASVR, manufactured by Nikkiso Co., Ltd.) was used as the measuring device, and the D50 value determined by volume-based measurement was taken as the average particle size.

[0075] [Measurement of average particle size of hollow particles] Measurement was performed using a laser diffraction particle size distribution analyzer (Mastersizer 3000 (Malvern)) by the dry measurement method. The average particle size was measured using the D50 value based on volume. In addition, for the hollow particles wet with water, the hollow particles obtained by drying them were measured for their average particle diameter.

[0076] [Measurement of moisture content] The moisture content of the heat-expandable microspheres and hollow particles was measured using a Karl Fischer moisture meter (Model MKA-510N, manufactured by Kyoto Electronics Manufacturing Co., Ltd.). W1 (%).

[0077] [Measurement of the content of the blowing agent in the heat-expandable microspheres] 1.0 g of the dried heat-expandable microspheres was placed in a stainless steel evaporating dish with a diameter of 80 mm and a depth of 15 mm, and its weight W3 (g) was measured. 30 mL of acetonitrile was added to disperse the microspheres evenly, and the microspheres were left at room temperature for 2 hours. After drying at 110°C for 2 hours, their weight W4 (g) was measured. The measured values ​​of W3, W4, and C W1 From this, the content CR1 (wt %) of the foaming agent was calculated using the following formula. CR1=((W3-W4) / 1.0)×100-C W

[0078] [Measurement of the content of components contained in hollow particles that vaporize upon heating] The content of components contained in the hollow particles that vaporize when heated was measured by headspace gas chromatography as follows. 0.1 g of hollow particles was weighed into a 20 mL headspace vial, and the headspace vial was sealed with a fluororesin-coated silicone rubber septum and an aluminum cap. The sealed headspace vial was heated at 170°C for 20 minutes, and then pressurized with helium for 0.5 minutes. 3 mL of the gas phase (headspace) was then sampled and introduced into a gas chromatograph to measure the content of components contained in the hollow particles that vaporize upon heating. The analytical conditions for headspace gas chromatography were as follows: (Analysis conditions) GC column: Agilent DB-624 (length 30 m, inner diameter 0.25 mm, film thickness 1.40 μm) Detector: FID, temperature 200℃ Temperature program: After holding at 40°C for 6 minutes, the temperature was increased to 200°C at a rate of 20°C / min. After reaching 0°C, the temperature was maintained for 3 minutes. Inlet temperature: 200℃ Gas introduction amount: 3mL Helium flow rate: 1 mL / min Split ratio: 10:1 The quantitative determination was carried out using a calibration curve method as follows. (Conditions for quantification method) A known amount of sample was dissolved in DMF, and 5 μL of the solution was placed in a 20 mL headspace vial. The vial was sealed with a fluororesin-coated silicone rubber septum and an aluminum cap. The sealed headspace vial was heated at 170°C for 20 minutes, pressurized with helium for 0.5 minutes, and 3 mL of the gas phase (headspace) was collected and introduced into a gas chromatograph. Regarding the fine particle-coated hollow particles, a pretreatment step was first performed to wash away the fine particles from the fine particle-coated hollow particles. Specifically, the fine particle-coated hollow particles were mixed with water, and optionally an acid or base, and the mixture was stirred to decompose or wash away the fine particles. The mixture was then filtered for solid-liquid separation. This procedure was repeated several times to obtain hollow particles from which the fine particles had been removed. For example, if the fine particles were calcium carbonate or magnesium hydroxide, hollow particles free of fine particles could be extracted by washing with hydrochloric acid or the like and then repeating the water washing process several times. The resulting hollow particles were then dried to adjust the moisture content to 1% or less (their ash content was analyzed and confirmed to be less than 5% by weight). The amount of components contained in the hollow particles that vaporize upon heating was measured in the same manner as above. The water-wet hollow particles were pretreated by drying them in an environment of 40°C or less to obtain hollow particles with a moisture content of 1% or less. The amount of components contained in the obtained hollow particles that vaporize upon heating was measured in the same manner as above.

[0079] [Measurement of ash content] The dried sample Wp (g) is placed in a crucible and heated with an electric heater at 700°C for 30 minutes to incinerate it, and the resulting ash Wq (g) is weighed. The ash content CA (wt%) of the sample is calculated from Wp (g) and Wq (g) using the following formula: CA(weight%)=(Wq / Wp)×100 Here, the ash content was measured using heat-expandable microspheres or hollow particles as the samples, each with a moisture content of 1% or less.

[0080] [Expansion start temperature (T S1 ) and maximum expansion temperature (T max1 ), maximum displacement (H max1 ) Measurement A DMA (DMA Q800, manufactured by TA Instruments) was used as the measuring device. 0.5 mg of heat-expandable microspheres was placed in an aluminum cup with a diameter of 6.0 mm (inner diameter of 5.65 mm) and a depth of 4.8 mm, and an aluminum lid (diameter of 5.6 mm, thickness of 0.1 mm) was placed on top of the heat-expandable microsphere layer to prepare a sample. The sample height was measured while a force of 0.01 N was applied from above using a pressure probe. With a force of 0.01 N applied using the pressure probe, the sample was heated from 20°C to 300°C at a heating rate of 10°C / min, and the displacement of the pressure probe in the vertical direction was measured. The temperature at which displacement in the forward direction began was defined as the expansion start temperature (T S1 ) and the maximum displacement (H max1 ) is the maximum expansion temperature (T max1 ) was decided.

[0081] [Re-expansion start temperature (T S2 ) and maximum re-expansion temperature (T max2 ) Measurement The measurement of the expansion initiation temperature and maximum expansion temperature was carried out in the same manner as above, except that 0.5 mg of hollow particles was used instead of 0.5 mg of heat-expandable microspheres. The temperature at which the displacement started in the positive direction was defined as the temperature at which the hollow particles started to re-expand (T S2 ) and the maximum displacement (H max2 ) is the maximum re-expansion temperature of the hollow particle (T max2 ) was decided. For the fine particle-coated hollow particles, the re-expansion starting temperature and maximum re-expansion temperature were measured in the same manner except that 3.0 mg of fine particle-coated hollow particles were used. For the water-wet hollow particles, hollow particles were obtained by the method described in the method for measuring the content of components contained in hollow particles that vaporize upon heating, and the re-expansion starting temperature and maximum re-expansion temperature of the obtained hollow particles were measured in the same manner as above.

[0082] [Measurement of true specific gravity (d1) of hollow particles] The true specific gravity (d1) of the hollow particles was measured by the immersion method (Archimedes method) using isopropyl alcohol in an atmosphere with an ambient temperature of 25°C and a relative humidity of 50%. Specifically, a 100 mL volumetric flask was emptied and dried, and then the weight of the volumetric flask (WB1) was weighed. The weighed volumetric flask was then filled with isopropyl alcohol exactly up to the meniscus, and the weight of the volumetric flask filled with 100 mL of isopropyl alcohol (WB2) was then weighed. A 100 mL volumetric flask was emptied and dried, and the weight of the volumetric flask (WS1) was then measured. Approximately 50 mL of hollow particles was then filled into the weighed volumetric flask, and the weight of the volumetric flask (WS2) was then measured. The volumetric flask filled with hollow particles was then filled with isopropyl alcohol exactly up to the meniscus, taking care to avoid air bubbles, and the weight (WS3) was then measured. The obtained WB1, WB2, WS1, WS2, and WS3 were then introduced into the following equation to calculate the true specific gravity (d1) of the hollow particles. d1={(WS2-WS1)×(WB2-WB1) / 100} / {(WB2-WB1)-(WS3-WS2)} In addition, for the fine particle-coated hollow particles or the water-wet hollow particles, the hollow particles were obtained by the method described in the method for measuring the content of components contained in hollow particles that vaporize upon heating, and the true specific gravity of the obtained hollow particles was measured in the same manner as above.

[0083] [Measurement of true specific gravity (d2) of hollow particles at maximum re-expansion] The true specific gravity (d2) of the hollow particles at maximum re-expansion was measured by the following method. A flat-bottomed box measuring 12 cm in length, 13 cm in width, and 9 cm in height was made from aluminum foil. 1.0 g of hollow particles or hollow particles with fine particles attached (hereinafter simply referred to as the hollow particle sample) was uniformly placed inside. The temperature was increased in 5°C increments from the re-expansion onset temperature obtained in the above measurement. After heating for 1 minute at each temperature, the true gravity of the re-expanded hollow particle sample was measured in the same manner as for the true specific gravity (d1) of hollow particles described above. The lowest true gravity among these was taken as the true specific gravity (d') of the hollow particle sample at maximum re-expansion. When the hollow particle sample is hollow particles, the true specific gravity (d') is the true specific gravity (d2) at maximum re-expansion. For the water-wet hollow particles, hollow particles were obtained by the method described in the method for measuring the content of components contained in hollow particles that vaporize upon heating, and the obtained hollow particles were measured as hollow particle samples. (Measurement of true specific gravity (d2) of hollow particles with fine particles attached at maximum re-expansion) When the hollow particle sample was a fine particle-coated hollow particle, hollow particles were obtained from the fine particle-coated hollow particle that showed the lowest true specific gravity using the method described in the measurement method for the content of components contained in hollow particles that vaporize upon heating. The true specific gravity of the obtained hollow particles was measured for true specific gravity (d2) at maximum re-expansion in the same manner as the measurement method for the true specific gravity (d1) of hollow particles described above.

[0084] [Measurement of the true specific gravity (d3) of hollow particles with fine particles attached] The true specific gravity (d3) of the fine particle-coated hollow particles was measured in the same manner as in the measurement of the true specific gravity (d1) of the hollow particles, except that fine particle-coated particles were used instead of the hollow particles.

[0085] [Residual particle ratio of hollow particles after immersion in methyl ethyl ketone] The particle remaining rate of the hollow particles after immersion in methyl ethyl ketone was measured as follows. First, 1.0 g of hollow particles was weighed into a 100 mL screw tube. Next, 50 mL of methyl ethyl ketone was added to the screw tube containing the hollow particles, and the tube was left to stand at 25°C for 24 hours to immerse the hollow particles in the methyl ethyl ketone. After 24 hours, the tube was centrifuged at 2000 rpm for 2 minutes, and the gel-like particles swollen by the methyl ethyl ketone were allowed to settle to the bottom. The hollow particles remaining at the top were transferred to an aluminum heat-resistant container (W1) and placed in a dryer to dry at 40°C for 24 hours. The weight of the aluminum heat-resistant container used was measured before transferring the remaining hollow particles (W1). After drying, the weight (W2) of the hollow particles and heat-resistant container was measured, the dry weight of the remaining hollow particles (W = W2 - W1) was determined, and the remaining rate of hollow particles was calculated using the following formula. Remaining rate of hollow particles (%) = (dry weight of remaining hollow particles (W) / 1.0) x 100 In addition, for the fine particle-coated hollow particles or the water-wet hollow particles, the hollow particles were obtained by the method described in the method for measuring the content of components contained in hollow particles that vaporize upon heating, and the obtained hollow particles were immersed in methyl ethyl ketone, and the particle residual rate of the hollow particles was measured in the same manner as above.

[0086] [Measurement of true specific gravity of the outer shell of hollow particles] The true specific gravity (dp) of the shell resin (thermoplastic resin constituting the shell) of the hollow particles was measured as follows. Specifically, 5 g of hollow particles were dispersed in 200 mL of N,N-dimethylformamide, then treated with an ultrasonic disperser for 30 minutes and allowed to stand at room temperature for 24 hours. After 24 hours, the mixture was dried under reduced pressure at 120°C for 5 hours to obtain a shell resin. The true specific gravity (d4) of the obtained shell resin was measured in the same manner as in the measurement of the true specific gravity (d1) of the hollow particles, except that the shell resin was used instead of the hollow particles. The measured true specific gravity of the shell resin was taken as the true specific gravity (dp) of the shell portion of the hollow particles.

[0087] [Measurement of the inner diameter (r1) and outer diameter (r2) of hollow particles] The inner diameter (r1) of the hollow particle was calculated from the measured true specific gravity (d1) of the hollow particle and the true specific gravity of the outer shell of the hollow particle (dp) using the following formula: Furthermore, the ratio (r1 / r2) of the inner diameter (r1) to the outer diameter (r2) was calculated. r1=(r2)×[{(dp)-(d1)} / (dp)] 1 / 3 r2 = (average particle diameter of hollow particles) / 2

[0088] [Measurement of Hollowness of Hollow Particles] From the measured inner diameter (r1) and outer diameter (r2) of the hollow particles, the hollow ratio of the hollow particles was calculated using the following formula. Hollow particle void ratio (%) = (r1 / r2) 3 ×100

[0089] [Measurement of specific gravity of heat-shielding composition] The specific gravity of the heat-shielding compositions obtained according to the procedures and proportions described in the Examples and Comparative Examples was measured by a method in accordance with JIS K 5600-2-4. Specifically, a 50 mL specific gravity cup (manufactured by TP Giken Co., Ltd.) was emptied and dried, and then the weight (WB3) of the specific gravity cup was measured. The weighed specific gravity cup was filled with the heat-shielding composition up to the brim, and then the lid was closed from above to fill the inside with the heat-shielding composition, and then the total weight (WB4) of the heat-shielding composition and the measuring cup was measured. Then, the liquid specific gravity (d5) of the heat-shielding composition was calculated from the weighed WB3 and WB4 using the following formula. d5=(WB4-WB3) / 50

[0090] (Production Example 1, Production Example of Heat-Expandable Microspheres) To 500 g of ion-exchanged water, 85 g of colloidal silica containing 20% ​​by weight of the active ingredient and 3 g of adipic acid-diethanolamine condensate containing 50% by weight of the active ingredient were added, and the pH of the resulting mixture was adjusted to 3.0 to 4.0 to prepare an aqueous dispersion medium. Separately, an oily mixture was prepared by mixing 125 g of acrylonitrile, 55 g of methacrylonitrile, 20 g of methyl methacrylate, 1.0 g of ethylene glycol dimethacrylate, 20 g of isobutane, 10 g of isopentane, and 2 g of di-2-ethylhexyl peroxydicarbonate. The aqueous dispersion medium and oil mixture were mixed, and the resulting mixture was dispersed in a homomixer at 12,000 rpm for 5 minutes to prepare a suspension. The suspension was transferred to a 1.5-liter pressure reactor and purged with nitrogen. The initial reaction pressure was adjusted to 0.2 MPa, and polymerization was carried out at 70°C for 15 hours with stirring at 80 rpm. The resulting polymerization product was filtered and dried to obtain heat-expandable microspheres 1 (Microspheres 1). The physical properties of the resulting Microspheres 1 are shown in Table 1.

[0091] (Production Examples 2 to 10, Production Examples of Heat-Expandable Microspheres) Heat-expandable microspheres 2 to 10 (microspheres 2 to 10) were obtained in the same manner as in Example 1, except that the aqueous dispersion medium and the components and amounts of the oily mixture were changed to those shown in Tables 1 and 2. The physical properties of the obtained heat-expandable microspheres are shown in Tables 1 and 2. In Tables 1 and 2, the following abbreviations are used: AIBN: 2,2'-azobis(isobutyronitrile) OPP: Di-2-ethylhexyl peroxydicarbonate (70% purity) Isobutane: 2-methylpropane, boiling point -12°C Isopentane: 2-methylbutane, boiling point 28°C

[0092] [Table 1]

[0093] [Table 2]

[0094] (Production Example A1, Method for producing hollow particles) The microspheres 1 obtained in Production Example 1 were heated by a dry thermal expansion method to produce hollow particles. The dry thermal expansion method employed was the internal injection method described in JP 2006-213930 A. Specifically, hollow particles were produced by thermally expanding heat-expandable microspheres using a manufacturing apparatus equipped with an expansion process unit as shown in Fig. 2 according to the following procedure.

[0095] (Explanation of the foaming process section) 2, the expansion process section comprises a centrally located gas inlet pipe (not shown) with a dispersion nozzle (11) at its outlet, an impingement plate (12) located downstream of the dispersion nozzle (11), an overheating prevention tube (10) spaced apart around the gas inlet pipe, and hot air nozzles (8) spaced apart around the overheating prevention tube (10). In this expansion process section, a gaseous fluid (13) containing heat-expandable microspheres flows in the direction of the arrow in the gas inlet pipe. A gas flow (14) flows in the direction of the arrow in the space formed between the gas inlet pipe and the overheating prevention tube (10) to improve the dispersibility of the heat-expandable microspheres and to prevent overheating of the gas inlet pipe and the impingement plate. Furthermore, a hot air flow for thermal expansion flows in the direction of the arrow in the space formed between the overheating prevention tube (10) and the hot air nozzle (8). Here, the hot air flow 15, the gaseous fluid 13, and the gas flow 14 generally flow in the same direction. A refrigerant flow 9 flows in the direction of the arrow inside the superheating protection tube 10 for cooling. (Manufacturing equipment operation) In the spraying step, a gaseous fluid (13) containing heat-expandable microspheres is introduced into a gas inlet pipe having a dispersion nozzle (11) at its outlet and located inside a hot air stream (15), and the gaseous fluid (13) is sprayed from the dispersion nozzle (11). In the dispersion process, the gaseous fluid (13) is caused to collide with an impingement plate (12) installed downstream of the dispersion nozzle (11) so that the heat-expandable microspheres are dispersed evenly in the hot air flow (15). Here, the gaseous fluid (13) discharged from the dispersion nozzle (11) is guided toward the impingement plate (12) together with the gas flow (14) and collides with it. In the expansion step, the dispersed heat-expandable microspheres are expanded by heating them to a temperature equal to or higher than the expansion initiation temperature in a hot air stream (15), and the resulting hollow particles are then collected by passing them through a cooling section or the like.

[0096] (Expansion conditions and results) In Production Example A1, the production apparatus shown in FIG. 2 was used, and the expansion conditions were a raw material supply rate of 0.8 kg / min and a raw material dispersion gas volume of 0.35 m 3 / min, hot air flow rate 8.0m 3 / min and a hot air temperature of 290°C to obtain hollow particles 1. The physical properties of the obtained hollow particles 1 are shown in Table 3.

[0097] (Production Examples A2 to A4 and Comparative Production Examples A1 to A3, Production Methods of Hollow Particles) Hollow particles were obtained in the same manner as in Production Example A1, except that the heat-expandable microspheres 1 obtained in Production Example 1 were replaced with the heat-expandable microspheres obtained in Production Examples 2 to 4 and 8 to 10, and the production conditions were changed as follows. The physical properties of the obtained hollow particles are shown in Tables 3 and 4. The modified hollow particle production conditions were as follows: Production Example A2: hot air temperature 240°C; Production Example A3: hot air temperature 220°C; Production Example A4: hot air temperature 270°C; Production Comparison Example A1: hot air temperature 280°C; Production Comparison Example A2: hot air temperature 260°C; and Production Comparison Example A3: hot air temperature 240°C.

[0098] (Production Example A5, Production Method of Water-Wet Hollow Particles) An aqueous dispersion (slurry) containing 3 wt% of the heat-expandable microspheres 5 obtained in Preparation Example 5 was prepared. According to the wet thermal expansion method described in JP-A-62-201231, the slurry was fed through a slurry inlet tube into an expansion tube (diameter 16 mm, volume 120 mL, made of SUS304TP) at a flow rate of 5 L / min. Steam (temperature: 147°C, pressure: 0.3 MPa) was then supplied through a steam inlet tube and mixed with the slurry to perform wet thermal expansion. The temperature of the slurry after mixing (expansion temperature) was adjusted to 115°C. The obtained slurry containing hollow particles was discharged from the protruding part of the foaming pipe, mixed with cooling water (water temperature 15°C), and cooled to 50 to 60°C. The cooled slurry liquid was dewatered using a centrifugal dehydrator to obtain a water-wet product (water content 67% by weight) containing 33% by weight of hollow particles 5. The obtained hollow particles 5 were isolated and their physical properties were measured. The results are shown in Table 3.

[0099] (Production Examples A6 to A7, Methods for producing water-wet hollow particles) Water-wet hollow particles were obtained in the same manner as in Production Example A5, except that the heat-expandable microspheres 5 obtained in Production Example 5 were replaced with the heat-expandable microspheres obtained in Production Examples 6 and 7, and the production conditions were changed as shown below. The obtained hollow particles were isolated and their physical properties were measured. The results are shown in Tables 3 and 4. The water-wet hollow particles were produced under the modified conditions of an expansion temperature of 125°C in Production Example A6 and 110°C in Production Example A7.

[0100] (Production Example A8, Production Method of Fine Particle-Coated Hollow Particles) 40 parts by weight of the heat-expandable microspheres 1 obtained in Production Example 1 and 60 parts of calcium carbonate (Whiten SB Red, manufactured by Bihoku Funka Kogyo Co., Ltd.) were mixed in a separable flask and then heated to 140°C over 5 minutes with stirring to obtain fine particle-coated hollow particles 8, whose physical properties were measured. The results are shown in Table 4.

[0101] (Production Example A9, Production Method of Fine Particle-Coated Hollow Particles) Microparticle-coated hollow particles 2 were obtained in the same manner as in Production Example A8, except that the heat-expandable microspheres 1 obtained in Production Example 1 were replaced with the heat-expandable microspheres obtained in Production Example 2, calcium carbonate was replaced with titanium oxide (Tipake CR-50, manufactured by Ishihara Sangyo Kaisha, Ltd.), and the heating temperature was increased to 120°C. The physical properties of the obtained microparticle-coated hollow particles 9 were measured. The results are shown in Table 4.

[0102] [Table 3]

[0103] [Table 4]

[0104] Example 1 A heat-shielding composition was obtained by adding 1.0 part by weight of hollow particles 1 to 50 parts by weight of a solvent-based urethane resin (Vylon UR-1400, manufactured by Toyobo Co., Ltd., active ingredient 30%, solvent: methyl ethyl ketone / isopropyl alcohol = 35 / 35), uniformly dispersing the mixture, and defoaming using a stirring defoamer. The resulting heat-shielding composition contained 40% by volume of hollow particles 1 and had a specific gravity of 0.74. Next, the obtained heat-shielding composition was applied to a 0.1 mm-thick OHP film using a coater so that the coating thickness after drying would be 300 μm, thereby obtaining Test Piece 1 having a heat-shielding material. The solar reflectance of the obtained Test Piece 1 was measured using the method described below. The results are shown in Table 5. The obtained heat-shielding composition 1 was then applied to a 0.8 mm thick aluminum plate using a coater so that the coating thickness after drying would be 300 μm, thereby obtaining test piece 2 having a heat-shielding material. The back surface temperature of the side of the obtained test piece 2 where the heat-shielding material was present was measured using the method described below. The results are shown in Table 5.

[0105] (Examples 2 to 6, Comparative Examples 1 to 9) Heat-shielding compositions were obtained in the same manner as in Example 1, except that the hollow particles 1 obtained in Production Example A1 were replaced with the hollow particles obtained in Production Examples A2 to A4, Production Examples A8 to A9, and Comparative Production Examples A1 to A3, and the amounts added were changed to those shown in Tables 5 and 6. The physical properties of each of the obtained heat-shielding compositions were measured. The results are shown in Tables 5 and 6. Furthermore, in Comparative Examples 4 to 8, heat-shielding compositions were obtained in the same manner as in Example 1, except that no hollow particles were added and other components shown in Table 6 were added in the amounts shown. The other components listed in Table 6 were as follows: Glass beads: Glass Bubbles VS5500 (3M Japan Ltd.) Calcium carbonate: Whiten SB Red (Bihoku Funka Kogyo Co., Ltd.) Titanium oxide: TITANIX JR-600A (manufactured by Teika Corporation) Next, using the obtained heat-shielding composition, test pieces 1 and 2 having heat-shielding materials were obtained in the same manner as in Example 1. The solar reflectance and back surface temperature of each of the obtained test pieces were measured and evaluated. The results are shown in Tables 5 and 6. In Comparative Example 9, only the solvent-based urethane resin was applied in the same manner as in Example 1 to obtain test pieces 1 and 2, which were then measured and evaluated.

[0106] Example 7 A heat-shielding composition was obtained by adding 7.5 parts by weight of the water-wet hollow particles 5 obtained in Production Example A5 (hollow particle content 33%) to 50 parts by weight of an aqueous urethane paint (aqueous gloss urethane for buildings, active ingredient 48%, transparent, manufactured by Dai Nippon Toryo Co., Ltd.) and uniformly dispersing the mixture. The obtained heat-shielding composition contained 40.7% by volume of hollow particles 1 and had a specific gravity of 0.80. Next, the obtained heat-shielding composition was applied to a 0.1 mm-thick OHP film and a 0.8 mm-thick aluminum plate using a coater, and test pieces 1 and 2 having heat-shielding materials were obtained in the same manner as in Example 1. The solar reflectance and back surface temperature of each of the obtained test pieces were measured in the same manner as in Example 1. The results are shown in Table 5.

[0107] (Examples 8 to 9) Heat-shielding compositions were obtained in the same manner as in Example 7, except that the water-moistened product of hollow particles 5 obtained in Production Example A5 was replaced with the water-moistened products of hollow particles obtained in Production Examples A6 and A7, and the amounts added were changed to those shown in Table 5. The physical properties of each of the obtained heat-shielding compositions were measured. The results are shown in Table 5. Next, using the obtained heat-shielding composition, test pieces 1 and 2 having heat-shielding materials were obtained in the same manner as in Example 1. The solar reflectance and back surface temperature of each of the obtained test pieces were measured and evaluated. The results are shown in Table 5.

[0108] Example 10 A heat-shielding composition was obtained in the same manner as in Example 1, except that the pigment Paliogen Black L 0086 was added in the amount shown in Table 5. The physical properties of the obtained heat-shielding composition were measured. The results are shown in Table 5. Next, using the obtained heat-shielding composition, test pieces 1 and 2 having heat-shielding materials were obtained in the same manner as in Example 1. The solar reflectance and back surface temperature of the obtained test pieces were measured and evaluated. The results are shown in Table 5.

[0109] Example 11 A heat-shielding composition was obtained in the same manner as in Example 7, except that the pigment Blue 5484K was added in the amount shown in Table 6. The physical properties of the obtained heat-shielding composition were measured. The results are shown in Table 6. Next, using the obtained heat-shielding composition, test pieces 1 and 2 having heat-shielding materials were obtained in the same manner as in Example 1. The solar reflectance and back surface temperature of each of the obtained test pieces were measured and evaluated. The results are shown in Table 6.

[0110] <Measurement of solar reflectance> The surface spectral reflectance of test piece 1 was measured in the measurement wavelength range of 300-2500 nm using a UV-Vis-IR spectrophotometer (Shimadzu Corporation: Solid Spec 3700). The solar reflectance was calculated from the obtained spectral reflectance based on JIS K 5602, and the heat shielding performance of the heat shielding material was evaluated according to the following criteria. ×: Solar reflectance is less than 50%. Good: Solar reflectance is 50% or more but less than 75%. 〇〇: Solar reflectance is 75% or more but less than 85%. 〇〇〇: Solar reflectance is 85% or more.

[0111] <Measurement of backside temperature> The heat shielding performance of the test piece 2 was evaluated using the test equipment shown in Fig. 3. The evaluation procedure was as follows. As shown in Figure 3, the top of an approximately 40 cm cube insulated container (17, polystyrene foam, etc.) was cut off, and a test piece (16, 0.8 mm thick aluminum plate) was placed on top of it with the coated side facing up. A thermocouple (18) for temperature sensing was fixed to the backside of the test piece with cellophane tape to measure the temperature change on the backside. A 50W reflector bulb (20) was used as the heat source, and light was irradiated perpendicularly from the test piece at a distance of 10cm. The backside temperature was measured 10 minutes after the start of irradiation. This backside temperature measurement was carried out in an atmosphere of 25°C and in a windless environment.

[0112] [Measurement of specific gravity of heat shielding material] The specific gravity of the heat-shielding material was measured in the same manner as in the measurement of the true specific gravity (d1) of the hollow particles, except that a heat-shielding material was used instead of the hollow particles. The heat-shielding material was cut into a size of 2 cm wide and 0.5 cm deep, and the measurement was carried out.

[0113] [Table 5]

[0114] [Table 6]

[0115] As can be seen from Tables 5 and 6, a heat-shielding composition containing specific hollow particles (A) whose outer shell contains a thermoplastic resin and a base component (B) can impart excellent heat-shielding performance with a solar reflectance of 50% or more, and a heat-shielding material obtained from this heat-shielding composition can prevent the back surface temperature of a component containing the heat-shielding material from becoming too high. On the other hand, when the composition contains hollow particles with an average particle size other than 0.1 to 50 μm (Comparative Example 1), hollow particles with an inner diameter to outer diameter ratio (r1 / r2) outside the range of 0.7 to 0.999 (Comparative Example 2), hollow particles with a particle survival rate of less than 50% after 24 hours of immersion in methyl ethyl ketone (Comparative Examples 1 and 3), or hollow particles (A) whose outer shell contains a thermoplastic resin (Comparative Examples 4 to 9), the solar reflectance is less than 50%, resulting in poor heat-shielding performance. Furthermore, heat-shielding materials obtained from these heat-shielding compositions increase the backside temperature of components incorporating the heat-shielding material. This is thought to be due to the poor dispersibility of the inorganic powder in the resin, which prevents it from being uniformly distributed throughout the resulting heat-shielding material, as seen in Comparative Examples 4 to 6. [Explanation of symbols]

[0116] 1 Hollow particles with fine particles attached 2 Outer shell 3 Hollow part 4 Microparticles (adsorbed state) 5. Microparticles (embedded, fixed) 8 Hot air nozzle 9 Refrigerant flow 10 Overheat prevention tube 11 Dispersion nozzle 12 Collision plate 13. Gas fluid containing heat-expandable microspheres 14 Gas Flow 15 Hot air flow 16 test specimens 17 Insulated container 18 Temperature Sensor 19 Temperature sensor body 20 reflector bulb (50W) 21 AC power supply

Claims

1. The present invention comprises hollow particles (A) having an outer shell containing a thermoplastic resin and a base component (B), the ratio (r1 / r2) of the inner diameter (r1) to the outer diameter (r2) of the particles (A) is 0.75 to 0.999; the average particle size of the particles (A) is 0.1 to 31.7 μm, the ratio (D90 / D50) of the volume-based cumulative 90% particle diameter (D90) of the particles (A) to the average particle diameter is 1.1 to 1.77; A heat-shielding composition, wherein the particle (A) has a particle residual rate of 50% or more after immersion in methyl ethyl ketone for 24 hours.

2. 2. The heat-shielding composition according to claim 1, wherein the thermoplastic resin is a polymer of a polymerizable component containing a monomer (C) having one polymerizable carbon-carbon double bond, the monomer (C) contains a nitrile-based monomer, and the content of the nitrile-based monomer is 30 parts by weight or more per 100 parts by weight of the monomer (C).

3. 3. The heat-shielding composition according to claim 1, wherein the content of said particles (A) is 0.001 to 20 parts by weight per 100 parts by weight of the content of said component (B).

4. The heat-shielding composition according to claim 1 or 2, which is a coating composition.

5. A heat-shielding material obtained by molding the heat-shielding composition according to claim 1 or 2.

6. A hollow particle used in a heat-shielding composition, the outer shell portion comprises a thermoplastic resin, The ratio (r1 / r2) of the inner diameter (r1) to the outer diameter (r2) is 0.75 to 0.999, The average particle size is 0.1 to 31.7 μm, a ratio (D90 / D50) of a volume-based cumulative 90% particle size (D90) to the average particle size is 1.1 to 1.77; Hollow particles having a survival rate of 50% or more after immersion in methyl ethyl ketone for 24 hours.

7. A microparticle-coated hollow particle comprising the hollow particle according to claim 6 and microparticles, wherein the microparticles are attached to the outer surface of the outer shell of the hollow particle.

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