Heat-shielding pigment, heat-shielding coating material, and coating film

Abstract

Provided is a heat-shielding pigment having high visible light transparency and high solar radiation reflectivity. This heat-shielding pigment is flat-shaped and has a particle diameter of 0.50-100 μm and has a layered structure including an electrical conductor layer and a dielectric layer which adjoin each other. The heat-shielding pigment is characterized in that at least one surface of the layered structure is coated with an organic compound and the amount of the organic compound coating on said one surface of the layered structure is greater than the amount of the organic compound coating on the other surface.

Description

Heat-shielding pigments, heat-shielding paints and coatings

[0001] The present invention relates to a heat-shielding pigment, a heat-shielding paint, and a coating film.

[0002] Heat-shielding paints with heat-shielding properties are sometimes used to paint the exteriors and parts of automobiles and buildings. Heat-shielding paints contain heat-shielding pigments that reflect or absorb infrared light. By using heat-shielding paints to paint the exteriors and parts of automobiles and buildings, it is possible to reduce the rise in the internal temperature of the automobile or building and the temperature of each part due to exposure to sunlight.

[0003] Among these, heat-shielding pigments that reflect infrared light with a high reflectance have high heat-shielding properties. Examples of pigments that reflect infrared light include metals such as silver and aluminum, and conductive materials such as alloys containing metals such as silver and aluminum. Furthermore, in order to reduce the effect on the color development of color-coated objects, pigments that reflect infrared light and transmit visible light are in demand. Patent Document 1 discloses a pigment having a laminate including a thin metal layer and a transparent dielectric layer.

[0004] International Publication No. 2016-006664

[0005] In heat-shielding pigments, solar reflectivity and visible light transmittance tend to be in a trade-off relationship. Therefore, it has been difficult to obtain a pigment that achieves both high solar reflectivity and high visible light transmittance. For example, to improve visible light transmittance, a transparent dielectric material can be used as a material constituting the outermost layer of a multi-layer pigment, but this can sometimes result in a decrease in infrared light reflectance.

[0006] Therefore, an object of the present invention is to provide a heat-shielding coating material that has high visible light transmittance and high solar radiation reflectance. Another object of the present invention is to provide a heat-shielding coating material that has high visible light transmittance and high solar radiation reflectance. Another object of the present invention is to provide a coating film that has high visible light transmittance and high solar radiation reflectance, and a building or a mobile object that has a coating film.

[0007] The above object can be achieved by the present invention, which provides a heat-shielding pigment having a particle size of 0.50 μm or more and 100 μm or less, in the form of a tabular heat-shielding pigment, which has a layered structure including a conductive layer and a dielectric layer adjacent to each other, wherein at least one surface of the layered structure is coated with an organic compound, and the amount of the organic compound coated on one surface of the layered structure is greater than the amount of the organic compound coated on the other surface of the layered structure.

[0008] According to the present invention, it is possible to provide a heat-shielding coating material having high visible light transmittance and high solar radiation reflectance. Furthermore, according to the present invention, it is possible to provide a heat-shielding coating material having high visible light transmittance and high solar radiation reflectance. According to the present invention, it is possible to provide a coating film having high visible light transmittance and high solar radiation reflectance, and a building and a mobile body having a coating film.

[0009] FIG. 1 is a perspective view of a heat-shielding pigment according to embodiment 1. FIG. 2 is a schematic cross-sectional view of a heat-shielding pigment according to embodiment 1. FIG. 3 is a schematic cross-sectional view of a heat-shielding pigment according to embodiment 1. FIG. 4 is a schematic cross-sectional view of a heat-shielding pigment according to embodiment 1. FIG. 5 is a cross-sectional image of a paint film according to embodiment 3. FIG. 6 is a schematic view showing a manufacturing process for a heat-shielding pigment according to an embodiment. FIG. 7 is a schematic view showing a manufacturing process for a paint according to an embodiment. FIG. 8 is a schematic view showing a manufacturing process for a paint film according to an embodiment.

[0010] The present invention will be described in further detail below with reference to preferred embodiments. In this specification, the region with a wavelength of 300 nm or more and less than 800 nm is referred to as the "visible light region." The region with a wavelength of 800 nm or more is referred to as the "infrared light region." The region with a wavelength of less than 300 nm is referred to as the "ultraviolet light region." In this specification, the physical film thickness may be simply referred to as the "film thickness." In this specification, a paint having heat-shielding properties may be referred to as a "heat-shielding paint," and a paint film coated with a heat-shielding paint may be referred to as a "heat-shielding film."

[0011] In the following, unless otherwise specified, a laminate refers to a combination of a substrate and an optically functional film, and a heat-shielding pigment refers to a material from which the substrate has been peeled off and a material having an organic compound in the outermost layer, unless otherwise specified.

[0012] The present inventors have investigated heat-shielding pigments that have high solar radiation reflectivity and high visible light transmittance. As a result, they have found that by dispersing the heat-shielding pigment in a coating film and arranging it at a small angle with respect to the air-side surface of the coating film, it is possible to efficiently reflect light other than visible light. Furthermore, they have found that it is preferable to distribute the heat-shielding pigment unevenly in the coating film, in a region close to the air-side surface.

[0013] As a result of further investigation, the inventors discovered that an effective configuration for arranging the heat-shielding pigment at a small inclination relative to the air-side surface of the coating film is one in which the heat-shielding pigment has an organic compound on its surface, with more of the organic compound on one side than on the other. The reason for this is thought to be that, when a large amount of highly hydrophobic organic compounds are attached to one side of the heat-shielding coating, the more hydrophobic side is more likely to be exposed on the air side of the coating film. Highly hydrophobic organic compounds have a higher affinity for air than for the solvent contained in the coating film, and therefore tend to be unevenly distributed on the air side.

[0014] Furthermore, it has been found that it is more preferable for the heat-shielding coating material to include a laminated structure having a conductive layer and a dielectric layer in order to efficiently transmit visible light and reflect infrared light, etc. The preferred laminated structure included in the heat-shielding coating material will be described later.

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments.

[0016] [Embodiment 1] <Heat-shielding pigment> The pigment of this embodiment is a multilayer pigment having at least two or more optically functional layers. In this specification, the pigment of this embodiment may be simply referred to as a heat-shielding pigment. The pigment can obtain heat-shielding properties by being contained in a medium such as a paint or a coating film. The pigment may have a substrate in addition to the optically functional layer, and may have an organic compound on its surface.

[0017] (Optical Functional Layer) The heat-shielding pigment of this embodiment is a multilayer pigment having at least two or more optical functional layers. The optical functional layer refers to a layer of a solid substance that reflects or diffuses visible light or infrared light. The optical functional layer in the heat-shielding pigment is a layer that controls the reflection and transmission of light, and includes two types of layers: a conductive layer that reflects light in the infrared region, and a dielectric layer that suppresses the reflection of light in the visible region through interference.

[0018] In this specification, a layer means a layer that exists on the surface of a substrate or another layer, is made of the same material, has continuity in the plane direction including the major axis of the pigment, and extends planarly to the edges. If a layer loses continuity due to being separated by other protruding layers or air spaces and is scattered on the surface of the substrate or another layer, it cannot be called a layer, and the desired optical properties cannot be obtained. To prevent the aforementioned separation, the film thickness of each layer is preferably 5 nm or more, more preferably 10 nm or more.

[0019] The film thickness and continuity of the optical functional layer can be measured by embedding the pigment in epoxy resin and observing the cross section of the resin with a transmission electron microscope. The material of each optical functional layer can also be analyzed by elemental analysis and composition analysis using energy dispersive X-ray spectroscopy (SEM-EDX) or the like after cross sectioning in a similar manner.

[0020] Generally, a conductor refers to a material having a resistivity of 1 Ωcm or less at room temperature. A dielectric refers to a material having a relative dielectric constant greater than 1. Generally, the refractive index of a dielectric is higher than that of a conductor. The conductor according to this embodiment is preferably a metal. The dielectric according to this embodiment preferably has an average refractive index of 1.70 or more, more preferably 2.00 or more, in the visible light wavelength range of 300 nm or more and 800 nm or less.

[0021] The dielectric constant is measured by an impedance analyzer. The dielectric constant can be measured, for example, by a 4990EDMS (manufactured by Toyo Corporation). The refractive index is measured by an ellipsometer. The refractive index can be measured, for example, by a VASE (manufactured by J.A. Woollam Japan).

[0022] Fig. 1 shows a perspective view of an example of a heat-shielding pigment according to embodiment 1. The heat-shielding pigment 1 includes, as optical functional layers, a conductor layer 2 and a dielectric layer 3. The conductor layer 2 includes an organic compound 4 such as a dispersant on the surface opposite to the dielectric layer 3.

[0023] 2A to 2D are schematic cross-sectional views of examples of the heat-shielding pigment according to embodiment 1.

[0024] The number of layers in the pigment and the number of optical functional layers are arbitrary. A first preferred embodiment, as shown in Fig. 2A, has two optical functional layers: a first optical functional layer which is a single conductor layer 2 and a second optical functional layer which is a single dielectric layer 3 adjacent to the first optical functional layer. A second preferred embodiment, as shown in Fig. 2B, has a first optical functional layer which is a conductor layer 2, a second optical functional layer which is a dielectric layer 3, and a third optical functional layer which is a conductor layer 2 in this order, i.e., a three-layer optical functional layer.

[0025] (First Optical Functional Layer) The heat-shielding pigment of this embodiment has a first optical functional layer on the outermost surface of the optical functional layers. The first optical functional layer is a conductor layer and is made of silver or an alloy containing 50% by mass or more of silver. Conductors such as metals reflect light over a wide wavelength range, and among these, an alloy containing 50% by mass or more of silver has low reflectance for light in the visible light range and is therefore preferred in terms of visible light transmittance. Examples of metals that can be used in alloys with silver include gold, copper, platinum, iron, magnesium, aluminum, titanium, and chromium. Examples of other metals include nickel, zinc, palladium, indium, tin, antimony, tantalum, tungsten, thallium, and lead.

[0026] The film thickness of the first optical functional layer (conductor layer) according to this embodiment must be 35 nm or less. If it is thicker than this, light will be reflected across all wavelengths, which is disadvantageous in terms of visible light transmittance. In order to achieve both solar reflectance and visible light transmittance, the film thickness of the first optical functional layer is preferably 5.0 nm or more and 35 nm or less.

[0027] Alloys that can be used for the conductive layer are described in detail below. The alloys can be used to suppress the aggregation that may occur over time when silver is used alone, and to suppress the reaction between sulfur atoms in the air and silver. When using a silver alloy containing any of Cu, Nd, and Zn, the content of each metal relative to silver is preferably 0.1 atomic % or more. This content provides the effect of suppressing the aggregation and reaction of silver.

[0028] Even more favorable effects can be expected if the contents of Cu, Nd, and Zn are increased to 0.2 atomic % or more, and even 0.3 atomic % or more. On the other hand, if the contents are too high, the haze of the heat shielding film may decrease (become cloudy) due to coloring by the alloy or oxidation of the alloy elements.

[0029] A commercially available silver alloy may be used. A silver alloy film can be produced using the silver alloy in a carousel-type reactive sputtering apparatus (RAS1100, manufactured by Synchron).

[0030] In the heat-shielding pigment of this embodiment, the first optical functional layer is located on the outermost surface of the optical functional layers. This is preferable from the viewpoint of solar reflectivity because it can directly reflect light incident on the pigment. The surface of the first optical functional layer may contain an organic or inorganic compound such as a dispersant. The organic or inorganic compound may completely cover the first optical functional layer to form a covering layer, but it is preferable that a portion of the first optical functional layer is exposed.

[0031] When the first optical functional layer is completely coated, it is desirable that the coating layer be optically negligible. Optically negligible means that when the heat-shielding pigment is present in a medium such as air or resin, it has the same refractive index as the medium. In other words, the difference in refractive index between the medium and the coating material is preferably 0.2 or less, and more preferably 0.1 or less. Furthermore, it is desirable that the thickness of the coating layer be within a range that does not optically affect the properties of the pigment. In other words, the thickness of the coating layer is preferably 5 nm or less, and more preferably 2 nm or less.

[0032] (Conductor Layer) The heat-shielding pigment of this embodiment may have an optional optical functional layer in addition to the first and second optical functional layers, or may have a conductive layer. The material and film thickness of the additional optical functional layer are not particularly limited. From the viewpoint of reflecting infrared light and transmitting visible light, the material and film thickness of the additional optical functional layer are preferably those used for the first or third optical functional layer or similar, and more preferably the same as those for the first optical functional layer.

[0033] In another preferred embodiment, a metal completely different from the above may be used to limit the reflected light to a specific wavelength. The metal may be, for example, gold, silver, copper, platinum, iron, magnesium, aluminum, titanium, chromium, or the like. The metal may also be nickel, zinc, palladium, indium, tin, antimony, tantalum, tungsten, thallium, lead, or the like. An alloy containing at least one of these metals may also be used.

[0034] (Second Optical Functional Layer) The heat-shielding pigment of this embodiment has a second optical functional layer, which is a dielectric layer, adjacent to the first optical functional layer, which is a conductor layer. The second optical functional layer is a dielectric layer that suppresses reflection of light in the visible light range of the adjacent conductor layer through an interference effect. The second optical functional layer (dielectric layer) is a dielectric having an average refractive index of 1.70 or more for light with a wavelength of 300 nm or more and 800 nm or less. Furthermore, the second optical functional layer is preferably transparent.

[0035] In general, the effect of suppressing reflected light due to interference works around a wavelength that is 4n times (n is an integer) the optical film thickness, which is the product of the refractive index and the film thickness. If the refractive index of the dielectric is high, the optical film thickness can be adjusted while keeping the film thickness of the dielectric layer thin, and therefore the film thickness of the heat-shielding pigment itself can be made thin. This has the advantages of suppressing a decrease in visible light transmittance due to light scattering, and making it easier for the pigment to be oriented in the medium when forming a coating film, thereby enabling efficient reflection of light.

[0036] From the above viewpoints, the refractive index of the dielectric layer is preferably 1.7 or more, and more preferably 2.0 or more. The optical film thickness of the dielectric layer is preferably 500 nm or less, and more preferably 180 nm or less. This is because if the dielectric layer is thicker than 500 nm, multiple interference effects will appear for coherent light, causing interference fringes and adversely affecting the visible light transmittance.

[0037] Furthermore, in order for a dielectric layer to transmit light in the visible light range, it is necessary to make corrections according to the wavelength range of the reflected light of the adjacent conductive layer. After careful consideration, it was found that in order to transmit a desired wavelength range, it is necessary to make corrections according to the wavelength range of the reflected light of the adjacent conductive layer. It was also found that the influence of the conductive layer is greater when conductive layers are adjacent to both sides of the dielectric layer than when a conductive layer is adjacent to one side of the dielectric layer.

[0038] In the coating film, the reflection spectrum of light incident on the conductive layer from the medium increases monotonically as the wavelength becomes longer. Furthermore, the thicker the film, the higher the reflectance for light with a shorter wavelength. In other words, the thicker the film, the more the rise in the reflection spectrum shifts toward the shorter wavelength side. For example, a 10-nm-thick Ag film exhibits a reflectance of 27% for light with a wavelength of 600 nm, while a 20-nm-thick Ag film exhibits a reflectance of 58%, with the rise shifting toward the shorter wavelength side.

[0039] That is, even if the total thickness of the conductive layers adjacent to the dielectric layer is the same, the shape of the spectrum differs when the dielectric layer is adjacent to one side (one side) compared to when two sets of stacked structures are adjacent to both sides (both sides), and the peak wavelength of the reflected light is shifted to the shorter wavelength side when the dielectric layer is adjacent to one side compared to when the two sets of stacked structures are adjacent to each other. Since the dielectric layer needs to cancel out the reflected light shifted to the shorter wavelength side and transmit it, the optical thickness needs to be thinner than when the dielectric layer is adjacent to both sides.

[0040] This configuration makes it possible to obtain the effect of interference correction at a wavelength equivalent to 4n times the optical thickness (n is an integer), resulting in high visible light transmittance. Furthermore, when conductive layers are adjacent to both sides of the dielectric layer, the peak tends to become sharper due to the overlap of reflected light, so it is necessary to apply thickness correction more strictly than when there is only one side.

[0041] Therefore, in a first aspect of this embodiment in which a conductor is adjacent to one side of a dielectric layer as depicted in Figure 2A, the optical thickness of the dielectric layer is preferably 0.50D or more and 20D or less, where D is the sum of the physical thicknesses of the adjacent conductor layers. It is even more preferable that it is 2.0D or more and 10D or less. It is even more preferable that the optical thickness of the dielectric layer is 2.0D or more and 8.0D or less, where D is the sum of the physical thicknesses of the adjacent conductor layers.

[0042] 2B , in a second aspect of the present embodiment in which conductors are adjacent to both sides of the dielectric layer, the optical film thickness of the second optical function layer is preferably 4.0D or more and 12D or less, where D is the total film thickness of the adjacent conductor layers. It is even more preferably 4.0D or more and 10D or less. This makes it possible to obtain an interference effect that corrects the wavelength corresponding to 4n times the optical film thickness (n is an integer) in accordance with the wavelength dependency of the light reflected by the conductor layer, thereby achieving high visible light transmittance.

[0043] In addition, in the third and fourth aspects of this embodiment, the first to third optical functional layers, which are conductive layers, have a thickness of 5.0 nm to 25 nm, and the second optical functional layer, which is a dielectric layer, uses a metal oxide or metal sulfide with a high refractive index. Because the thickness of the conductive layer is fixed, the thickness of the dielectric can be adjusted without correction. That is, in the third aspect of this embodiment, the thickness of the second optical functional layer is adjusted to a range of 5.0 nm to 500 nm, preferably 5 nm to 120 nm. In the third aspect of this embodiment, the thickness of the second optical functional layer is adjusted to a range of 30 nm to 180 nm. This allows only light in the visible light range to be suppressed by interference, achieving the same effects as the first and second aspects of this embodiment.

[0044] The material used in the dielectric layer is not particularly specified in the first or second embodiment, and may be an organic compound or a polymer compound as long as it has a high refractive index, but is preferably one used in the third or fourth embodiment. In the third or fourth embodiment, the dielectric layer contains 50 parts by weight or more of an oxide or sulfide of a metal selected from the group consisting of titanium, niobium, tantalum, zirconium, cerium, zinc, copper, silicon, hafnium, yttrium, magnesium, and indium. More preferably, the dielectric layer contains 50 parts by weight or more of an oxide of a metal selected from the group consisting of titanium, niobium, tantalum, zirconium, and cerium.

[0045] Specific examples include titanium dioxide, titanium monoxide, titanium trioxide, niobium pentoxide, tantalum pentoxide, zirconium oxide, cerium oxide, MU3, zinc sulfide, silicon, MU2-C, and GL2. Other examples include MU2, hafnium oxide, silicon monoxide, yttrium oxide, magnesium oxide, and indium tin oxide (ITO). More preferred examples include titanium dioxide, titanium monoxide, titanium trioxide, niobium pentoxide, tantalum pentoxide, zirconium oxide, and cerium oxide.

[0046] (Dielectric Layer) The heat-shielding pigment of this embodiment may have an optional optical functional layer in addition to the first and second optical functional layers, and may be a dielectric layer. The material and film thickness are not particularly limited, but the dielectric layer has the role of canceling out the reflection of the conductor layer and increasing visible light transmittance, and therefore is preferably one of the examples of the second optical functional layer or a similar material, and more preferably the same as the second optical functional layer.

[0047] (Substrate) The optical functional layer of this embodiment may be formed on a substrate. The optical functional layer may be formed on one side or both sides of the substrate. The substrate may be a conductive layer, a dielectric layer, or neither. From the viewpoint of reducing the influence on reflected light in the infrared light region, the refractive index of the substrate is preferably 1.65 or less.

[0048] Furthermore, from the viewpoint of visible light transmittance, the substrate is preferably transparent. Examples of materials used for the substrate include glass, polyethylene terephthalate (PET), mica, gelatin, collagen, fibroin, polyester, polyurethane, polyolefin, and polystyrene. Examples of materials used for the substrate include acrylic resin, polyvinyl chloride, polyvinyl acetate, polyamide, polyimide, polycarbonate, epoxy resin, acrylonitrile / butadiene / styrene copolymer (ABS resin), and silica. More preferably, examples of materials used for the substrate include glass, polyethylene terephthalate (PET), mica, and silica.

[0049] A release layer may be provided on the surface of the substrate. The release layer is preferably made of an acrylic resin. A known method can be used to form the release layer. The material constituting the release layer is applied to the surface of the substrate by, for example, a bar coater method, a spin coater method, a spray method, or the like. By providing a release layer on the surface of the substrate, the laminate of the optical functional layer, which is the raw material for the multilayer pigment, can be peeled from the substrate and used.

[0050] A support layer may also be provided on the surface of the release layer or the substrate. The support layer may be made of any material that mechanically reinforces the optical multilayer film, and the material is not limited. The support layer is also included in the pigment after the substrate is removed. Therefore, from the viewpoint of reducing the influence on reflection and transmission, the support layer is preferably transparent, and the refractive index of the support layer is preferably 1.65 or less. The thickness of the support layer is preferably 200 nm or less, more preferably 100 nm or less.

[0051] The support layer can be formed by any of the well-known vapor phase synthesis methods such as CVD and PVD, and liquid phase synthesis methods such as sol-gel. This allows a transparent layer, which is a precursor material for the support layer, to be formed on the surface of the substrate, and then tabular crystals primarily composed of alumina, silica, or an oxide such as silica can be provided on the surface of the substrate. For example, providing a silica support layer below the optical functional layer has the advantage of reinforcing the mechanical strength of the pigment, making it less susceptible to bending or shattering.

[0052] (Organic Compound) At least one surface of the heat-shielding pigment of this embodiment is coated with an organic compound. When both surfaces (both the main outermost surface and the other outermost surface) are coated, the amount of coating on one surface is greater than the amount of coating on the other surface. In particular, it is preferable that the weight ratio of the amount of coating on one surface to the amount of coating on the other surface is 1.20 or more.

[0053] The organic compound is used to uniformly disperse the heat-shielding pigment in a medium such as a paint, coating film, etc. The organic compound is fixed to the material that forms the outermost surface of the heat-shielding pigment by physical adsorption or chemical bonding, and improves the wettability of the heat-shielding pigment to the solvent of the heat-shielding paint and suppresses aggregation of the pigments.

[0054] Furthermore, as a result of investigations by the present inventors, they found that the heat-shielding pigment according to this embodiment is unevenly distributed in the vicinity of the air-side surface in the coating film, and that when a highly hydrophobic organic compound is used, the abundance ratio of the pigment in the vicinity of the air-side surface is 1.10 times or more the abundance ratio of the pigment in the center of the film.

[0055] Focusing on the hydrophobicity of organic compounds, the solubility parameter (SP value) of organic compounds that tend to cause pigments to be unevenly distributed in the vicinity of the air-side surface is 20 (J / cm ３ ) １／２ It was found that the SP value of air is 9 to 11 (J / cm ３ ) １／２ Therefore, it is presumed that the surface having a highly hydrophobic organic compound on its surface is likely to be on the air side of the coating film.

[0056] The organic compound that can be used in the heat-shielding pigment of this embodiment is preferably a compound that contains, in its molecule, both a moiety that bonds to or adsorbs to the material on the outermost surface of the heat-shielding pigment and a moiety that is highly hydrophobic and has high solvent affinity.

[0057] The heat-shielding pigment according to this embodiment may be used in either a water-based paint or a solvent-based paint. Examples of solvents for solvent-based paints include toluene, xylene, ethyl acetate, butyl acetate, N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, and dioxane. Organic compounds suitable for solvent-based paints have hydrophilic groups as sites for physical adsorption or chemical bonding, and hydrophobic groups as sites with high affinity for the solvent.

[0058] Preferred examples of the hydrophilic group include at least one functional group selected from the group consisting of an amino group, a hydroxy group, a carboxy group, a phosphate group, and a sulfo group. These functional groups may have a counter ion and be ionized.

[0059] Preferred examples of hydrophobic groups include substituted or unsubstituted hydrocarbon groups having 2 to 30 carbon atoms. A substituted hydrocarbon group is, for example, a hydrocarbon group in which one or more carbon atoms are substituted with a hydrophilic group. Also, for example, a hydrocarbon group is a hydrocarbon group in which one or more carbon atoms are substituted with an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or a substituent formed from a combination of these atoms. Examples of the substituent include an ether group, a ketone group, an amide group, an ester group, a carbonyl group, a sulfinyl group, a phosphoryl group, an alkyl group, and a phenylene group.

[0060] The organic compound of this embodiment is an amphiphilic material having both hydrophilic and hydrophobic moieties. Therefore, the organic compound may be in a molecular state, an emulsion state, or a regularly arranged state such as a micelle or vesicle, as long as it contributes to improving the dispersibility of the heat-shielding coating material.

[0061] Preferred examples of the organic compound include alkyl carboxylic acid derivatives, alkyl sulfonic acid derivatives, and alkyl phosphonic acid derivatives. Specifically, the organic compound is preferably at least one organic compound selected from the group consisting of stearic acid, oleic acid, palmitic acid, stearyl sulfonic acid, oleyl sulfonic acid, stearyl phosphonic acid, oleyl phosphonic acid, octadecyl phosphonic acid, decane sulfonic acid, hexyl phenyl phosphonic acid, decyl mercaptomethyl phosphonic acid, and 10-carboxydecyl phosphonic acid. The organic compound may also be a salt thereof.

[0062] In addition to the above, examples of organic compounds that can be suitably used in metal films that form conductive layers include alkylamine derivatives. Specific examples include propylamine, hexylamine, hexadecanamine, stearylamine, octadecaneamine, tetradecaneamine, 5-(aminomethyl)undecane, and cyclooctylamine. The organic compound may be an ammonium salt of these.

[0063] Furthermore, an organic compound selected from among commonly known dispersants can also be used. In this case, the dispersant is preferably designed to have a structure that includes a moiety that can adsorb or chemically bond to the heat-shielding pigment and a hydrophobic moiety, and the hydrophobic moiety extends toward the medium containing the solvent in the case of a heat-shielding paint, or toward the resin in the case of a heat-shielding film.

[0064] A typical example is an organic compound called a comb dispersant. A comb dispersant has a main chain and two or more hydrophobic groups as side chains in one polymer molecule. The main chain contains the hydrophobic group described above, which physically adsorbs or chemically bonds to the heat-shielding pigment. The hydrophobic group is preferably a substituted or unsubstituted hydrocarbon group having 2 to 30 carbon atoms.

[0065] The substituted hydrocarbon group may be a group in which one or more carbon atoms are replaced by an oxygen atom, a nitrogen atom, a sulfur atom, a halogen atom, or a combination of these atoms. Specifically, the substituted hydrocarbon group is a group in which an ether group, a ketone group, an amide group, an ester group, a carbonyl group, a sulfinyl group, or a phosphoryl group is substituted. Furthermore, the substituted hydrocarbon group may be an alkyl group such as a methyl group or a propyl group, or a phenylene group. Specifically, examples include long-chain alkyl groups and long-chain alkyl groups containing oxyalkylene groups. Furthermore, the terminal portion of the long-chain alkyl group containing an oxyalkylene group is preferably a hydrocarbon group having 3 or more carbon atoms. If the number of carbon atoms is less than 3, hydrophobicity may be reduced.

[0066] The organic compound may be a polymer. As the polymer organic compound, it is preferable to use at least one polymer selected from the group consisting of polyvinyl alcohol, acetalized polyvinyl alcohol, polyethylene copolymer, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid copolymer.

[0067] (Solubility parameter) The solubility parameter of the organic compound is 20 (J / cm ３ ) １／２ Preferably, the solubility parameter in this specification is the Hansen solubility parameter. The Hansen solubility parameter is composed of energy (δd) derived from intermolecular dispersion forces, energy (δp) derived from intermolecular dipole interactions, and energy (δh) derived from intermolecular hydrogen bonds. These three parameters can be regarded as coordinates in a three-dimensional space.

[0068] The solubility parameter can be calculated using the following method (Hansen sphere method) for both known and unknown organic compounds. The solubility parameter space (Hansen sphere) is specified by plotting the three components δdm, δpm, and δhm described above in three-dimensional space. Multiple pure substances (substances consisting of a single component) with known solubility parameters are plotted, and the Hansen sphere is specified based on the solubility of the organic compound in the pure substance. The solubility parameter of the organic compound can be calculated by determining the center value of the Hansen sphere.

[0069] The solubility parameter of the evaluation sample can also be calculated using the atomic group contribution method from information on the average molecular structure. In the case of the atomic group contribution method, the solubility parameter of an organic compound can be calculated using, for example, computer software Hansen Solubility Parameters in Practice (HSPiP). It is now known that even values ​​calculated using software do not deviate significantly from experimental values ​​obtained by the Hansen sphere method.

[0070] (Coating Amount of Organic Compound) The coating amount of the organic compound was determined by quantifying the organic compound using a thermogravimetric differential thermal analyzer (TG / DTA STA7200, manufactured by Hitachi High-Tech Science).

[0071] First, 10 mg of the sample was placed in an aluminum pan and the weight loss was measured in the temperature range of 250°C to 400°C. Because organic compounds decompose and vaporize in the temperature range of 250°C to 400°C, this weight loss was taken as the weight of the organic compounds adsorbed or chemically bonded to the surface of the thermal barrier coating. Next, the coating amount (mass %) or the weight ratio of the coating amount on the outermost surface to the coating amount on the other outermost surface was calculated from the weight of the organic compounds obtained.

[0072] The coating amount was calculated using the following formula.

[0073]

[0074] In contrast, in the case of a heat-shielding coating material in which both surfaces (both the main outermost surface and the other outermost surface) are coated, the weight ratio of the coating amount on the outermost surface to the coating amount on the other outermost surface was calculated as follows.

[0075] First, the weight A (g) of the organic compound in the heat-shielding pigment coated on only one side was calculated using the above measurement method. Next, the weight B (g) of the organic compound in the heat-shielding coating material coated on both sides was determined, and the difference in the amount of the organic compound was taken as the weight B-A (g) of the organic compound on the other outermost surface, and the weight ratio of the coating amount on the outermost surface to the coating amount on the other outermost surface was calculated using the following formula:

[0076]

[0077] In a heat-shielding coating material in which both surfaces (both the main outermost surface and the other outermost surface) are coated, the coating amounts on each surface are different, and it is preferable that the weight ratio between the coating amount on the outermost surface and the coating amount on the other outermost surface is 1.20 or more.

[0078] Furthermore, a cross-sectional image of the heat-shielding film can be measured using a field emission scanning electron microscope (FE-SEM) (S-5500, manufactured by Hitachi High-Technologies), and the presence or absence of an organic compound on the surface of the heat-shielding pigment in the film and the thickness of the layer made of the organic compound can be calculated. Since the microscope can calculate a film thickness of about 0.5 nm if the accelerating voltage is set to 30 kV, the weight ratio of the coating amount can be estimated from the film thickness of the organic compound film formed on each surface of the heat-shielding pigment.

[0079] (Particle Size) The particle size of the heat-shielding pigment of this embodiment is not particularly limited, but is preferably 0.50 μm or more and 100 μm or less. It is more preferably 1.0 μm or more and 30 μm or less, and even more preferably 2.0 μm or more and 20 μm or less. If the particle size is too small, local plasmon resonance may occur at the edge of the conductive layer, resulting in light absorption, which is disadvantageous in terms of both solar reflectivity and visible light transmittance. On the other hand, if the particle size is too large, it is disadvantageous in terms of the sedimentation properties of the coating material and dispersibility in the medium.

[0080] The particle size of a pigment can be quantified as the Feret diameter of a projected particle image. The Feret diameter is the length of the perpendicular line formed by sandwiching a projected particle between two parallel lines in a fixed direction. The particle size of a pigment can be quantified, for example, by dispersing the pigment in a common solvent, spraying it on a glass plate, and then drying it, and observing the particle size with a common optical microscope. Alternatively, the particle size and its distribution can be measured by image analysis using an injection-type image analysis particle size distribution analyzer (IF-3200, manufactured by Jasco International) when the pigment is dispersed in a common solvent. Examples of common solvents include acetone and hexafluoroisopropanol.

[0081] (Thickness of Pigment) The thickness of the heat-shielding pigment of this embodiment is not particularly limited, but is preferably 100 nm or less, and more preferably 60 nm or less. A thinner pigment has the advantages of being able to suppress a decrease in visible light transmittance due to light scattering, and of being more easily oriented in a medium, thereby enabling efficient reflection of light. The thickness of the pigment can be measured, for example, by cutting out a cross section of the pigment embedded in a resin such as epoxy and using a scanning electron microscope or a transmission electron microscope.

[0082] (Pigment Shape) The heat-shielding pigment of this embodiment has a plate-like shape. Although there is no particular problem if the plate-like particles are warped, a small curvature is preferable, and a rigid plate with a curvature of 0 is most preferable. A curvature of 0 is most advantageous in terms of solar reflectivity, because incident sunlight can be reflected uniformly across the entire surface. The shape of the pigment can be measured, for example, by cutting out a cross section of the pigment embedded in a resin such as epoxy and using a scanning electron microscope or a transmission electron microscope.

[0083] <Method for producing a heat-shielding pigment> Fig. 1 is a schematic diagram of a heat-shielding pigment coated with an organic compound according to this embodiment, and Figs. 2A to 2D are cross-sectional views of the heat-shielding pigment coated with an organic compound according to this embodiment.

[0084] 2A and 2B show a flat-plate-shaped heat-shielding pigment 1 in which a conductive layer 2 and a dielectric layer 3 are laminated, and the heat-shielding pigment has an organic compound 4 on only one surface. There are no particular limitations on the production method as long as the heat-shielding pigment can be obtained, but in this embodiment, the heat-shielding pigment was produced in accordance with the "First production method" described below as an example of the production method.

[0085] 2C and 2D show heat-shielding pigments having organic compounds on both surfaces, with the amount of the organic compound coated on one surface being greater than the amount of the organic compound coated on the other surface. There are no particular limitations on the production method as long as a heat-shielding pigment can be obtained, but in the present invention, the heat-shielding pigment was produced in accordance with the "Second Production Method" which will be described later as an example of the production method.

[0086] 4A shows an example of a pigment manufacturing process using a sputtering method. Specifically, a target material for forming a TiO2 layer is sputtered onto a flat PET film substrate to form a TiO2 layer. Then, a target material for forming an Ag layer is sputtered to laminate an Ag layer on the TiO2 layer, and an organic compound layer is then layered on top to produce a laminate.

[0087] [First Production Method] To obtain a heat-shielding pigment having an organic compound on only one surface, at least a step of obtaining a flat-plate-shaped heat-shielding pigment in which a conductive layer and a dielectric layer are laminated on a base material, and a step of applying an organic compound to the surface of the heat-shielding pigment that is not in contact with the base material are essential.

[0088] Specifically, first, conductive layers and dielectric layers are alternately formed and laminated on a substrate, which may be made of a metal material, a polymer material, an oxide material, glass, or the like.

[0089] The metal material may be any metal material commonly used for substrate applications. Specific examples include various stainless steels such as SUS304, SUS316, SUS316L, SUS420J2, and SUS630. Other examples include gold, platinum, silver, copper, nickel, cobalt, titanium, iron, aluminum, and tin. Other examples include various alloys such as nickel-titanium (Ni-Ti) alloy, nickel-cobalt (Ni-Co) alloy, cobalt-chromium (Co-Cr) alloy, and zinc-tungsten (Zn-W) alloy. Other examples include inorganic materials such as various ceramic materials, and even metal-ceramic composites.

[0090] Various resin films can be used as the polymer material. Specific examples include polyolefin film, polyester film, polyvinyl chloride, cellulose triacetate, and water-soluble film. Specific examples include polyvinyl alcohol (PVA), polyacrylic acid polymer, polyacrylamide (PAM), and polyethylene oxide (PEO). Polyester film and water-soluble film are preferably used as the polymer material. Polyester film (hereinafter referred to as polyester) is preferably a polyester having film-forming properties and consisting primarily of a dicarboxylic acid component and a diol component.

[0091] Among the polyesters mentioned above, from the viewpoints of transparency, mechanical strength, dimensional stability, etc., terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred as the dicarboxylic acid component. Furthermore, polyesters having ethylene glycol or 1,4-cyclohexanedimethanol as the main constituent component are preferred as the diol component. Of these, polyesters having polyethylene terephthalate or polyethylene naphthalate as the main constituent component are preferred. Furthermore, copolymer polyesters consisting of terephthalic acid, 2,6-naphthalenedicarboxylic acid, and ethylene glycol are preferred. Furthermore, polyesters having a mixture of two or more of these polyesters as the main constituent component are preferred.

[0092] Examples of oxide materials that can be used include titanium dioxide, aluminum oxide, zirconium oxide, and silicon dioxide.

[0093] The thickness of the substrate is not particularly limited, but is preferably 0.01 nm or more and 10 mm or less.

[0094] The substrate of this embodiment also includes a substrate having a resin layer formed on the above-described substrate, the resin layer being made of a water-soluble resin such as polyvinyl alcohol, or a solvent-soluble resin such as polyvinyl butyral, an acrylic resin, or a methacrylic resin. If the resin layer is soluble in a solvent, it functions as a release layer. The release layer may be formed by a conventionally known method, such as by bar coating, dipping, spin coating, or spraying. The use of a substrate having a release layer makes it easy to peel off the substrate and obtain the heat-shielding pigment of the present invention.

[0095] When a resin layer made of polyvinyl alcohol is provided as a release layer, it can be removed using warm water at 50° C. or higher. When a resin layer made of polyvinyl butyral is provided as a release layer, it can be removed using an alcohol such as methanol. Furthermore, when a resin layer made of acrylic resin is provided as a release layer, it can be removed using a solvent such as methyl ethyl ketone (MEK).

[0096] Methods for forming a laminate of optical functional layers on a substrate include chemical vapor deposition (CVD), sputtering, solution coating, electron beam evaporation, ion plating, etc. Among these, chemical vapor deposition (CVD), sputtering, and solution coating are preferred.

[0097] In the solution coating method, a liquid containing a material for forming the optical functional layer, such as a metal-containing solution or a dielectric-containing solution, is prepared, and these are alternately coated and dried to form the heat-shielding pigment.

[0098] Examples of coating methods include roll coating, rod bar coating, air knife coating, and spray coating. Other methods include slide-type curtain coating, slide hopper (slide bead) coating, and extrusion coating.

[0099] Next, the step of applying an organic compound to the surface of the heat-shielding pigment that is not in contact with the substrate will be described. The method of treating the surface of the heat-shielding pigment with an organic compound involves selecting a solvent that dissolves the organic compound, preparing a solution of the organic compound, and mixing the solution with the heat-shielding pigment or applying the solution onto the heat-shielding coating material.

[0100] In the case of mixing, the heat-shielding pigment containing the organic compound is obtained by stirring for at least one hour, removing only the solvent by centrifugation, filtration, or the like, and then drying. On the other hand, in the case of coating, the heat-shielding pigment containing the organic compound is obtained by applying the above-mentioned solution by a method such as roll coating or rod bar coating, and then drying. Other coating methods that can be used include air knife coating, spray coating, slide-type curtain coating, slide hopper (slide bead) coating, and extrusion coating.

[0101] In order to enhance the effect of physical adsorption or chemical bonding of the organic compound to the surface of the heat-shielding pigment, only the surface of the heat-shielding coating material may be ionized (anionized or cationized) in advance using an acid or alkali. Alternatively, pretreatment may be performed using a material having an active group, or the above two methods may be combined. The active group is —OH, —SH, or ═NH, where O is an oxygen atom, S is a sulfur atom, N is a nitrogen atom, and H is a hydrogen atom. Furthermore, to enhance the activity, the active group may be bonded to a metal atom.

[0102] A typical example of pretreatment is aluminate treatment, which is a technique in which the heat-shielding paint is placed in an aqueous sodium aluminate solution, sulfuric acid is added to maintain the pH of the system at about 6.5, and the paint is immersed for at least one hour, followed by filtering and washing with water, thereby forming hydrous alumina (hydrated aluminum oxide) on the surface of the heat-shielding pigment.

[0103] Another example is the sol-gel method, in which a solution of an organometallic compound or the like is hydrolyzed and polycondensed to form a sol, which is then gelled, and heated to attach the metal oxide having the above-mentioned active group.

[0104] The heat-shielding pigment is basically a heat-shielding pigment that has undergone the above-described steps, but it also includes a heat-shielding pigment that is used when forming a paint or a coating film, i.e., a heat-shielding pigment from which the substrate has been peeled off or which has been further pulverized.

[0105] The substrate can be peeled off in two ways: by using a solvent that dissolves part or all of the substrate, or by mechanical peeling. The case where a solvent is used is as described above.

[0106] When pulverizing, the material is pulverized to a desired size. The pulverizing device is not particularly limited, and examples thereof include an ultrasonic device, a vibration mill, a ball mill, a bead mill, a jet mill, a paint shaker, and a high-speed stirring device. When pulverizing in a solvent, the solvent is not particularly limited as long as it does not inhibit the physical adsorption or chemical bonding of the organic compound. In addition, when pulverizing in a dry manner instead of wet pulverization using the above-mentioned device, the material may be cooled with liquid nitrogen or the like to harden it and then pulverized.

[0107] [Second Production Method] The second production method is a method for producing a heat-shielding pigment in which, when the heat-shielding pigment has an organic compound on both surfaces, the coating amount of the organic compound on one surface is greater than the coating amount of the organic compound on the other surface. There is a difference in weight between the coating amount on the main outermost surface and the coating amount on the other outermost surface, and in particular, it is preferable that the weight ratio be 1.20 or more. The process follows the already-described [First Production Method] up to the step of obtaining a heat-shielding pigment having an organic compound on only one surface.

[0108] First, after obtaining a heat-shielding pigment having an organic compound present on only one surface by the method described in [First Production Method], an additional step is added. The additional step is to treat the pigment again with an organic compound after peeling off the substrate. In this step, both surfaces are treated with the organic compound almost evenly, so that the side that was previously treated with the organic compound is treated even more thickly.

[0109] [Embodiment 2] <Heat-shielding paint> The heat-shielding paint of this embodiment is a heat-shielding paint that contains a multilayer pigment having at least two or more optical functional layers, similar to the heat-shielding pigment of Embodiment 1, and a resin component that is an organic solvent and a resin or a resin composition. The heat-shielding paint may contain other components. Furthermore, the heat-shielding pigment may have a large amount of organic compound on one side, and may be a pigment different from the pigment described in Embodiment 1. FIG. 4B shows an example of a paint production process for producing a heat-shielding paint. That is, a laminate of optical functional layers formed on a PET substrate is dissolved and peeled off, and ultrasonic pulverization is performed as necessary, and the obtained heat-shielding pigment is dispersed in a dispersion. Thereafter, the dispersion in which the heat-shielding pigment is dispersed is washed and the solvent dispersion is removed, and a suitable solvent is added to the paint to produce the heat-shielding paint.

[0110] (Organic Solvent) The heat-shielding coating of this embodiment contains an organic solvent. The organic solvent may be one that is used in general coatings. For example, alcohols (methanol, ethanol, isopropanol, n-butyl alcohol, ethylene glycol, etc.), ketones (acetone, methyl ethyl ketone, etc.), esters (ethyl acetate, butyl acetate, etc.), etc. may be used. Alternatively, halides (chloroform, methylene chloride, etc.), olefins (butane, hexane, etc.), ethers (tetrahydrofuran (THF)), butyl ether, dioxane, etc.), aromatics (benzene, xylene, toluene, etc.), amides (N,N-dimethylformamide, dimethylacetamide), etc. may be used. Mixtures of these solvents may also be used.

[0111] (Resin Component) The resin component containing the resin or resin composition in the heat-shielding coating material of this embodiment may be a resin used in a general coating material. Examples of the resin component include acrylic resin, polyester resin, alkyd resin, fluororesin, epoxy resin, polyurethane resin, and polyether resin. The resin component may be one-component curing or two-component curing, and either may be used.

[0112] (Amount of Heat-Shielding Pigment) The amount of heat-shielding pigment in the heat-shielding coating material of this embodiment is not particularly limited, but is preferably 0.50 mass % or more and 10 mass % or less relative to the resin component. More preferably, it is 1.0 mass % or more and 5.0 mass % or less. Light incident on the coating film obtained when the solvent in the coating material has dried is reflected by the surface of the heat-shielding pigment. If the amount of heat-shielding pigment in the coating material is too small relative to the resin component contained in the coating material, the amount of light that reaches the pigment surface will be small, which is disadvantageous in terms of solar reflectivity. On the other hand, if the content is too large, the amount of light that reaches the pigment surface will increase, resulting in a corresponding decrease in visible light transmittance.

[0113] Furthermore, when the heat-shielding pigments do not overlap each other and completely cover a surface parallel to the film surface, a favorable balance between reflectance and visible light transmittance is achieved. If the ratio of the pigment weight to the resin component weight in this case is taken as the coated PB ratio, the coated PB ratio can be calculated using the following formula:

[0114]

[0115] On the other hand, if the ratio of the heat-shielding pigment weight to the resin component weight in the paint is defined as the paint PB ratio, the amount of paint relative to the ideal amount can be calculated as the surface density using the following formula.

[0116]

[0117] In reality, because pigment particles overlap and tilt, adjusting the blending amount so that the surface density is 100% will not result in a 100% coverage, but this formula can be used as a guide to determine the approximate blending amount. The pigment coverage of a heat-shielding film can be measured by image analysis of an optical microscope image taken at a perpendicular angle to the film surface. The blending amount of pigment in the paint can be calculated by washing away all components other than the pigment from the paint, leaving only the pigment.

[0118] (Particle size, thickness, and shape of the heat-shielding pigment) The particle size, thickness, and shape of the heat-shielding pigment in the heat-shielding coating material of this embodiment are similar to those of the heat-shielding pigment in embodiment 1. By washing away components other than the pigment in the coating material, it is possible to leave only the pigment, which can be analyzed using a method similar to the analysis method for the heat-shielding pigment. The organic solvent in the coating material can be suitably used for washing, and heating or drying may be performed during washing.

[0119] [Embodiment 3] <Coating Film> The coating film of this embodiment is a heat-shielding film containing a multilayer pigment having at least two or more optically functional layers, similar to the heat-shielding pigment of embodiment 1, and a resin component that is a resin or a resin composition. Other components may also be contained. The coating film of this embodiment may be simply referred to as a heat-shielding film. Figure 4C shows an example of the manufacturing process for the coating film. The heat-shielding paint described above is prepared, and a coating process is carried out to form a coating film on the surface of the substrate. The coating film contains a resin component and the heat-shielding pigment described above. The formed coating film exhibits a heat-shielding function when the heat-shielding pigment receives light that is incident on the surface of the coating film.

[0120] (Arrangement of Pigment in Coating Film) As described above, in a coating film containing a heat-shielding pigment coated with an organic compound, the heat-shielding pigment may be unevenly distributed in the vicinity of the film surface (the portion close to the air interface) of the coating film. For example, it has been found that when a heat-shielding pigment coated with a hydrophobic organic compound is used in a solvent-based paint, the presence ratio of the heat-shielding pigment in the vicinity of the air-side surface in the coating film is high.

[0121] The abundance ratio can be calculated as follows. For example, a coating film containing a heat-shielding pigment is embedded in a resin such as epoxy, and a cross section is cut out and observed using a scanning electron microscope. For example, an image of a cross section cut out to a length of 35 μm to 45 μm is prepared, with any thickness, and the section is divided horizontally into three equal parts: a film surface vicinity, a central portion, and a lower portion. The number of heat-shielding pigment particles of 0.5 μm or larger visible in each layer is counted, and the ratio of the number in the film surface vicinity to the central portion is calculated and used as the abundance ratio.

[0122] From the viewpoint that the heat-shielding pigment can be unevenly distributed and aligned in the vicinity of the air-side surface of the coating film, thereby achieving more efficient heat insulation, it is preferable that the abundance ratio of the heat-shielding pigment in the vicinity of the film surface is 1.10 times or more relative to that in the central part of the film.

[0123] (Tilt of the heat-shielding pigment) In the heat-shielding film of this embodiment, if the tilt of the pigment relative to the surface of the optical functional layer relative to the air-side surface of the coating film is small, solar radiation incident on the surface layer of the heat-shielding film can be more easily received by the optical functional layer, and therefore, by configuring it in this way, solar reflectivity can be improved. When a coating material using the heat-shielding pigment of this embodiment is applied to any substrate and dried, a coating film with a small tilt can be obtained. Light that enters the coating film from the air hits the pigment in the coating film, and only when the reflected light does not undergo total reflection at the interface between the coating film and the air does it return to the air as reflected light.

[0124] When the pigment is not tilted, the light enters the air at the same angle as when it was incident, so total reflection does not occur. On the other hand, as the tilt of the pigment increases, the angle of incidence when it enters the air becomes larger, making total reflection more likely to occur and causing the reflected light to attenuate. For this reason, it is desirable to have a small tilt of the pigment.

[0125] The heat-shielding pigment of this embodiment has an exposed conductive layer made of silver on its surface, and because of its high affinity with air, it is likely to be oriented on the surface of the coating film, resulting in a small tilt. The average tilt of the pigment relative to the air-side surface of the coating film is preferably 20° or less, and more preferably 10° or less. The tilt of the pigment can be calculated by observing the cross section of the coating film with a transmission electron microscope and performing image analysis. The average tilt is calculated as the number average of the tilts calculated by image analysis.

[0126] (Resin) The resin used in the heat-shielding coating material of this embodiment may be one that is used in general coating materials, such as acrylic resin, polyester resin, alkyd resin, fluororesin, epoxy resin, polyurethane resin, polyether resin, etc. Note that a resin composition containing additives and solvents in addition to the resin may also be used. Resins or resin compositions are available in one-component curing types and two-component curing types, and either may be used.

[0127] (Amount of Heat-Shielding Pigment) The amount of heat-shielding pigment in the heat-shielding film of this embodiment is not particularly limited, but is preferably 0.50 mass % or more and 10 mass % or less relative to the resin component. More preferably, it is 1.0 mass % or more and 5.0 mass % or less. Light incident on the heat-shielding film obtained by drying the solvent in the paint is reflected by the surface of the heat-shielding pigment.

[0128] If the amount of heat-shielding pigment blended relative to the resin component contained in the paint is small, the amount of light reaching the pigment surface will be small, which is disadvantageous in terms of solar reflectivity.On the other hand, if the content is too high, the amount of light reaching the pigment surface will increase, resulting in a corresponding decrease in visible light transmittance.

[0129] Furthermore, when the heat-shielding pigments completely cover a plane parallel to the film surface without overlapping with each other, a favorable balance between reflectance and visible light transmittance is achieved. The blending amount of the heat-shielding pigment in the film can be determined by mass analysis or thermal analysis.

[0130] The blending amount of the heat-shielding pigment in the film can be determined, for example, using a thermogravimetric differential thermal analyzer (TG / DTA STA7200, manufactured by Hitachi High-Tech Science). 10 mg of a heat-shielding film sample is placed in an aluminum pan, and the weight loss in the temperature range of 250°C to 400°C is measured. Because organic compounds decompose and vaporize in the temperature range of 250°C to 400°C, the weight of the resin component in the heat-shielding film can be quantified by measuring the weight loss. The weight of the heat-shielding pigment in the heat-shielding film can be quantified by measuring the remaining weight.

[0131] (Analysis of Heat-Shielding Pigment) The heat-shielding film of this embodiment contains a heat-shielding pigment. The film thickness and continuity of the optical functional layer in the heat-shielding pigment can be measured by embedding the pigment in an epoxy resin and observing a cross-section of the resin using a transmission electron microscope. Furthermore, the material of each optical functional layer can be analyzed by elemental analysis and composition analysis using energy dispersive X-ray spectroscopy (SEM-EDX) or the like after a cross-section is taken using a similar method.

[0132] <Multilayer Coating Film> The coating film of this embodiment may be a multilayer coating film having different coating layers in the upper and lower layers. For example, the lower layer preferably has an architectural base coat or an automotive base coat, and may be a water-based or oil-based coat. Furthermore, for example, the upper layer preferably has an architectural clear coat or an automotive clear coat. The base coating film primarily functions to impart and maintain aesthetic appeal and design to the substrate on which the multilayer coating film is formed. The base coating film is formed by applying a base paint. The base paint may be either a solvent-based or water-based paint.

[0133] <Substrate> The heat shielding film of the present embodiment may be used for at least a part of the exterior or parts of an automobile, which is an example of a moving body. Examples of moving bodies include automobiles, aircraft, drones, ships, etc. The heat shielding film may also be used for at least a part of the exterior or parts of a building. Alternatively, for example, the heat shielding film may be directly applied to metal or plastic materials for an automobile.

[0134] The heat-shielding film of this embodiment is preferably applied on a coating film coated with a primer paint such as a cationic electrodeposition paint, and in some cases, an intermediate paint. The building may be a residence, a warehouse, or a container. In both automobiles and buildings, the longer the exposure time to a solar radiation environment, the higher the heat-shielding and temperature-suppressing effects. For this reason, the film is preferably used in trucks, warehouses, containers, and the like that store precision instruments, food, etc.

[0135] <Method of Measuring Heat Shielding Property and Solar Reflectance> The heat shielding property of the heat shielding film of this embodiment can be evaluated by solar reflectance. Solar reflectance can be measured by the method described in JIS K A5602:2008. Specifically, an integrating sphere unit (ISN-923, manufactured by Jasco International) of a spectrometer (V-670, manufactured by Jasco International) is used to measure solar reflectance. Solar reflectance can be calculated by obtaining a reflection spectrum of wavelengths from 200 nm to 2300 nm at an incident angle of 5° and multiplying it by the weighting specified in JIS.

[0136] <Method for Measuring Visible Light Transmittance> The visible light transmittance of the heat shielding film of this embodiment can be evaluated by visible light transmittance. The visible light transmittance can be measured by the method described in JIS K A5759:2008. Specifically, using the same spectrophotometer as used to measure the solar reflectance, a transmission spectrum of wavelengths from 200 nm to 2300 nm is obtained at an incident angle of 5°, and the transmittance can be calculated by multiplying it by the weights described in JIS.

[0137] [Examples] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples as long as it does not depart from the gist of the invention. "Parts" and "%" used to describe the amounts of components are based on mass unless otherwise specified.

[0138] <Preparation of Substrate> (Production of Substrate 1) A polyvinyl alcohol solution was applied to a PET film (trade name "Lumirror (registered trademark) T60", manufactured by Toray Industries, Inc.) measuring 85 x 85 mm and 188 μm thick, so that the dry film thickness was 1 μm. As the polyvinyl alcohol solution, an 11% by mass aqueous solution of polyvinyl alcohol (trade name "Denka Poval K-17", saponification degree: 90 to 100 mol%, manufactured by Denka) was used. The PET film was then dried in an oven at 80°C for 1 hour to form a release layer, and this was used as Substrate 1.

[0139] (Preparation of Substrate 2) An acrylic resin was applied to a PET film (trade name "Lumirror (registered trademark) T60" manufactured by Toray Industries, Inc.) measuring 85 x 85 mm and having a thickness of 188 μm, so that the dry film thickness was 1 μm. An acrylic resin (trade name "Acrydic A-405" manufactured by DIC Corporation) was used as the acrylic resin. The PET film was then dried in an oven at 80°C for 1 hour to form a release layer, which was used as substrate 2.

[0140] (Preparation of Substrate 3) A polyvinyl butyral solution was applied to a PET film (trade name "Lumirror (registered trademark) T60", manufactured by Toray Industries, Inc.) measuring 85 x 85 mm and 188 μm thick, so that the dry film thickness was 1 μm. The polyvinyl butyral solution used was a 10 mass % methanol solution of polyvinyl butyral (trade name "Mobital B20H", hydroxyl group content: 18 to 21 wt %, manufactured by Kuraray Co., Ltd.). The PET film was then dried in an oven at 80°C for 1 hour to form a release layer, which was used as substrate 3.

[0141] <Formation of Optical Functional Layer> (Preparation of Laminates (1) to (10) and Comparative Laminates (1) to (6)) Next, an optical functional layer including a dielectric layer or a metal layer was formed on the prepared substrate to obtain laminates (1) to (10) and comparative laminates (1) to (6). The configurations of the substrate and optical functional layer used in each laminate are shown in Table 1. The dielectric layer and metal layer were formed by an electron beam method using a vacuum deposition apparatus (EX-200, manufactured by ULVAC).

[0142] The laminate embedded in the epoxy resin was observed under a transmission electron microscope to measure the thickness of the laminate. The measurement results of the thickness of each optical functional layer are shown in Table 1.

[0143] The refractive index of the material of the dielectric layer, which is the second optical functional layer, was measured using an ellipsometer (VASE, manufactured by J.A. Woollam Japan). The average refractive index n, physical film thickness d, and optical film thickness nd of the measured second optical functional layer in the wavelength range of 300 nm to 800 nm are shown in Table 1. Table 1 also shows D, which is the total film thickness of the first optical functional layer and the third optical functional layer, and the value obtained by dividing the optical film thickness of the second optical functional layer by D.

[0144] The deposition materials used for each optical functional layer shown in Table 1 are as follows: Ag: silver (manufactured by ULVAC) TiO ２ : Titanium dioxide (manufactured by ULVAC) Ag / Pd / Cu: Silver / palladium / copper alloy (product name "APC-TR", composition: (silver content 97.4 wt%, palladium content 0.91 wt%, copper content 1.69 wt%), manufactured by Furuya Metal) Nb ２ O ５ : Niobium pentoxide (manufactured by Astron) Al ２ O３ : Aluminum oxide (manufactured by Astron) Al: Aluminum (manufactured by Ulvac)

[0145]

[0146] <Preparation of Pigments> (Pretreatment) The samples to be pretreated were pretreated using the following aluminate treatment method. Laminates (1) to (6), (10) and comparative laminates (1) to (4) were cut into strips and placed in glass bottles with lids. Distilled water and 5% by mass of sodium aluminate (Kishida Chemical Co., Ltd.) based on the laminate were added to the glass bottle. The pH of the system was then adjusted to 6 to 9 using 0.18 mol / L sulfuric acid. The glass bottle was shaken at 60°C for 1 hour to perform surface treatment of the laminate. The mixed solution containing the laminate was filtered and washed using Kiriyama filter paper (5C, Kiriyama Manufacturing Co., Ltd.). After washing, the laminate was dried to obtain a laminate surface-treated with aluminum oxide.

[0147] (Treatment with organic compounds) The pretreated laminates (1) to (6), (10) and the comparative laminates (1) to (4) were treated with organic compounds. Similarly, the non-pretreated laminates (1) to (2), (7) to (9), and the comparative laminates (5) to (6) were treated with organic compounds.

[0148] Each laminate, 5% by mass of an organic compound relative to the laminate, and a solvent were placed in a container. The organic compounds and solvents used are shown in Tables 2-1 and 2-2. The container was shaken overnight at room temperature (25°C) to perform surface treatment of the laminate. The mixed solution containing the laminate was filtered and washed using Kiriyama filter paper (5C, manufactured by Kiriyama Seisakusho). The washed laminate was dried to obtain a laminate surface-treated with an organic compound.

[0149] (Removal of substrate) The laminate and the solvent were placed in a glass bottle and shaken for 1 hour, thereby dissolving the release layer and peeling the substrate from the laminate.The laminate was then washed with a solvent to obtain a slurry containing the laminate.A portion of the slurry was taken and dried, and the organic compounds contained in the laminate were quantified using a thermogravimetric differential thermal analyzer (TG / DTA STA7200, manufactured by Hitachi High-Tech Science) according to the method described above.

[0150] (Pulverization of Laminate) The slurry containing the laminate was pulverized in an ultrasonic pulverizer for 10 seconds to 10 minutes to obtain pigments (1) to (16) and comparative pigments (1) to (6). The pulverization time varied depending on the case, and the pulverization operation was stopped when the particle size reached the desired particle size of 10 μm.

[0151] Furthermore, pigment (17) was obtained by carrying out the same process as in the preparation of pigment (1) using laminate (1), except that the ultrasonic pulverization time was changed to 10 seconds. Furthermore, pigment (18) was obtained by carrying out the same process as in the preparation of pigment (1) using laminate (1), except that the ultrasonic pulverization time was changed to 20 minutes. The particle size and specific gravity of the obtained pigment are shown in Tables 2-1 and 2-2.

[0152] (Treatment of Both Surfaces with an Organic Compound) When the heat-shielding pigment having an organic compound on only one surface obtained by the above-described process is further treated with an organic compound as a raw material, a heat-shielding pigment having an organic compound on both surfaces can be obtained. In addition, a heat-shielding pigment having different coverage rates on one surface and the other surface can be obtained.

[0153] The crushed pigment was filtered through Kiriyama filter paper (5C, manufactured by Kiriyama Seisakusho) to remove the solvent, and then 5% by mass of an organic compound and solvent relative to the heat-shielding pigment were added. The container containing the pigment, organic compound, and solvent was shaken overnight at room temperature (25°C) to perform a surface treatment on the pigment. The surface-treated pigment was filtered through Kiriyama filter paper (5C, manufactured by Kiriyama Seisakusho), washed, and dried to obtain pigments (14) to (16) having the organic compound on both sides. The laminates, organic compounds, and solvents used to prepare pigments (14) to (16) are shown in Table 2-2.

[0154] Furthermore, comparative pigments (2) to (4) were prepared by treating both surfaces with an equal amount of an organic compound. The laminate, organic compound, and solvent used in preparing comparative pigments (2) to (4) are shown in Table 2-2.

[0155]

[0156]

[0157] <Preparation of Paints> Paints were prepared using each pigment so as to achieve the paint P / B ratio shown in Table 3. An acrylic resin solution (trade name "Acrydic A405", manufactured by DIC) was added to each pigment. The mixed materials were kneaded using a planetary centrifugal mixer (Awatori Rentaro ARE-310, manufactured by Thinky) to obtain paints (1) to (18) and comparative paints (1) to (6).

[0158]

[0159] <Preparation and Evaluation of Coating Films> (Preparation of Coating Films) Using a spray gun (WIDER1, manufactured by Anest Iwata), the coating materials (1) to (18) and the comparative coating materials (1) to (6) were spray-coated onto a PET film (trade name "Lumirror (registered trademark) T60", manufactured by Toray Industries) at a pressure of 1.0 MPa. The coated PET film was dried at room temperature and atmospheric pressure for one day to obtain coating films (1) to (18) and comparative coating films (1) to (6) with a film thickness of 20 μm.

[0160] (Evaluation of coverage and tilt of pigment in coating film) Measurement was performed from the top surface of the obtained heat-shielding film using an optical microscope (BX53M, manufactured by Olympus), and the coverage was calculated using image analysis. In addition, the cross section of the obtained heat-shielding film was measured using a scanning electron microscope (SU3800, manufactured by Hitachi, Ltd.), and the tilt distribution was calculated from the obtained SEM image. The number-average tilt was calculated as the average value (average tilt) of the tilt of the pigment relative to the air-side surface of the coating film.

[0161] (Abundance ratio of heat-shielding pigment in coating film) A cross-sectional image of a coating film cut out at an arbitrary thickness in a length range of 35 μm to 45 μm was prepared. For example, FIG. 3 is a cross-sectional image of a coating film (1) cut out in a length of 40 μm. The cross-sectional image was divided into thirds in the horizontal direction (parallel to the air-side surface of the coating film), into a film surface vicinity portion (a), a central portion (b), and a lower portion (c). The number of heat-shielding pigment particles of 0.5 μm or larger visible in each layer was counted, and there were 10 particles in (a) and 4 particles in the central portion (b). Therefore, the abundance ratio was 10 / 4 = 2.5. The abundance ratio of the heat-shielding pigment in the heat-shielding film in the film surface vicinity portion was calculated using the method described above.

[0162] (Optical Properties) Using an ultraviolet-visible-infrared spectrophotometer (V-670, manufactured by JASCO Corporation), the reflectance and transmittance of the coating film were measured continuously from the ultraviolet region to the near-infrared region. Based on the obtained data, the solar reflectance and visible light transmittance were calculated in accordance with the method described in JIS K 5602 of the JIS standard. In addition, the solar reflectance and visible light transmittance were evaluated according to the following criteria. Table 4 shows the preparation conditions and evaluation results of the coating film.

[0163] <Evaluation criteria for solar reflectivity> Rank A: Solar reflectivity is 40% or more, and is excellent in solar reflectivity. Rank B: Solar reflectivity is 30% or more and less than 40%, which is within the acceptable range. Rank C: Solar reflectivity is less than 30%, and is low in solar reflectivity, and cannot be used as a heat-shielding film.

[0164] <Evaluation criteria for visible light transmittance> Rank A: Visible light transmittance is 65% or more, and is excellent in visible light transmittance. Rank B: Visible light transmittance is 60% or more and less than 65%, and is within the acceptable range. Rank C: Visible light transmittance is less than 60%, and no visible light is transmitted.

[0165]

[0166] <Use of silver alloy and weather resistance evaluation> In the present invention, in addition to using a silver / palladium / copper alloy (Ag / Pd / Cu: 97.4 / 0.91 / 1.69 [wt %], manufactured by Furuya Metal) as in the coating film (4) described above, it is also possible to use a silver alloy within a range where the silver content is maintained at 50 wt %. Specific embodiments are shown below.

[0167] [Form, composition, and content of silver alloy] Specific examples of the form, composition, and content of silver alloys are shown in Tables 5-1 and 5-2, but the present invention is not limited thereto. All of the silver alloys used were purchased sputtering targets manufactured by Furuya Metal Co., Ltd.

[0168] [Examples 55 to 81] [Production of Coating Film (1) and Coating Film (4)] Coating film (1) and coating film (4) were obtained by the above-mentioned production procedure.

[0169] [Production of Coating Films (19) to (43)] The production of laminates was carried out in accordance with the production procedure for laminate (1), except that the silver alone was changed to a silver alloy shown in Tables 5-1 and 5-2. Furthermore, the production of pigments or paints was carried out in accordance with the production procedure for pigment (1) or paint (1), except that the silver alone was changed to a silver alloy shown in Table 1. Finally, the production of coating films was carried out in accordance with the production procedure for coating film (1), except that the silver alone was changed to a silver alloy shown in Table 1, to obtain coating films (19) to (43).

[0170] In addition, the average refractive index n, film thickness d, and the product thereof, optical thickness nd, of TiO2, which is the second optical functional layer, in the wavelength range of 300 nm to 800 nm, and the film thickness D of the silver alloy, which is the first optical functional layer, were calculated, and the values ​​obtained by dividing the optical thickness by D are shown in Tables 5-1 and 5-2.

[0171] [Weather Resistance Evaluation] The resulting coating film was placed in a Super Xenon Weather Meter Sx75 (Ibiden Co., Ltd.) and subjected to a xenon exposure test at an irradiance of 180 W / m@2 @ 350 nm for 472 hours at a temperature of 50°C and a humidity of 55% RH.

[0172] In addition, the annual UV dose is 360x10 ６ (J / m ２ ) ÷ irradiance of light source 180 (W / m ２ ) ÷ 3600 seconds / hour = 472 hours, so this exposure test is equivalent to one year of outdoor exposure time.

[0173] The results of measuring the solar reflectance of the heat-shielding coating film after exposure are shown in the table. The results show that the solar reflectance of the silver-only film decreased by about 4%, but in the case of the silver alloy, no decrease in solar reflectance was observed before and after exposure. The reason for this is unknown, but there were some coatings whose solar reflectance increased slightly after exposure.

[0174] From the above results, it was found that the use of a silver alloy containing 90% or more, more preferably 97% or more, of Ag by weight of the metal species provides better light resistance than silver alone.

[0175]

[0176]

[0177] <Preparation of multilayer coating film> Aluminum sheet metal spray-coated with a base coating agent (trade name "nax Admira (registered trademark) Alpha 611 Chinching Black NP", manufactured by Nippon Paint) was overcoated with paint (2) and dried to obtain a multilayer coating film (1). It was confirmed that the multilayer coating film (1) can be used as a heat-shielding coating on top of a colored paint without impairing the design.

[0178] A top coating agent (trade name "nax Aegis (registered trademark) RS Clear" manufactured by Nippon Paint) was spray-coated onto the multilayer coating film (1) to obtain a multilayer coating film (2). The multilayer coating film (2) was not scraped even when scratched with a fingernail, and it was confirmed that the mechanical strength was sufficiently high.

[0179] The disclosure of this embodiment includes the following configurations and methods.

[0180] (Configuration 1) A heat-shielding pigment having a flat plate-like particle size of 0.50 μm or more and 100 μm or less, and a laminated structure formed including a conductive layer and a dielectric layer adjacent to each other, wherein at least one surface of the laminated structure is coated with an organic compound, and the coating amount of the organic compound on one surface of the laminated structure is greater than the coating amount of the organic compound on the other surface of the laminated structure.

[0181] (Configuration 2) The solubility parameter of the organic compound is 20 (J / cm ３ ) １／２ 2. The heat-shielding pigment according to claim 1, wherein:

[0182] (Configuration 3) The heat-shielding pigment according to Configuration 1 or 2, wherein the organic compound is an organic compound that includes a substituted or unsubstituted hydrocarbon group having 2 to 30 carbon atoms, and at least one functional group selected from the group consisting of an amino group, a hydroxy group, a carboxy group, a phosphate group, and a sulfo group.

[0183] (Configuration 4) The heat-shielding pigment according to any one of Configurations 1 to 3, wherein the organic compound is a comb-shaped dispersant having, in its main chain, at least one functional group selected from the group consisting of an amino group, a hydroxy group, a carboxy group, a phosphate group, and a sulfo group, and having, in its side chain, a substituted or unsubstituted hydrocarbon group having 2 to 30 carbon atoms.

[0184] (Configuration 5) The heat-shielding pigment according to Configuration 1 or 2, wherein the organic compound includes at least one polymer selected from the group consisting of polyvinyl alcohol, acetalized polyvinyl alcohol, polyethylene copolymer, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid copolymer.

[0185] (Configuration 6) The heat-shielding pigment according to any one of Configurations 1 to 5, wherein the weight ratio of the coating amount of the organic compound on one surface of the laminate structure to the coating amount of the organic compound on the other surface is 1.20 or more.

[0186] (Structure 7) The heat-shielding pigment according to any one of Structures 1 to 6, wherein the laminated structure is formed by one conductor layer and one dielectric layer adjacent to each other, the conductor layer is made of silver or an alloy containing 50 mass % or more of silver, and has a physical film thickness of 5.0 nm or more and 35 nm or less, the dielectric layer is made of a dielectric material having an average refractive index of 1.70 or more in the wavelength range of 300 nm or more and 800 nm or less, and the optical film thickness of the dielectric layer is 0.50 D or more and 20 D or less, where D [nm] is the physical film thickness of the conductor layer.

[0187] (Structure 8) The heat-shielding pigment according to any one of Structures 1 to 6, wherein the laminate structure is formed by at least three optical functional layers, a first optical functional layer of the laminate structure is made of silver or an alloy containing 50% by mass or more of silver, and has a physical film thickness of 5.0 nm or more and 35 nm or less, a second optical functional layer adjacent to the first optical functional layer is made of a dielectric material having an average refractive index of 1.70 or more in the wavelength range of 300 nm to 800 nm, and a third optical functional layer adjacent to the second optical functional layer is made of silver or an alloy containing 50% by mass or more of silver, and has a physical film thickness of 5.0 nm or more and 35 nm or less, and the optical film thickness of the second optical functional layer is 4.0 D or more and 12 D or less, where D [nm] is the sum of the physical film thicknesses of the first optical functional layer and the third optical functional layer.

[0188] (Configuration 9) The heat-shielding pigment according to any one of configurations 1 to 6, wherein the thickness of the heat-shielding pigment is 100 nm or less.

[0189] (Configuration 10) A heat-shielding coating material comprising the heat-shielding pigment according to any one of Configurations 1 to 9, an organic solvent, and a resin.

[0190] (Configuration 11) A coating film comprising the heat-shielding pigment according to any one of Configurations 1 to 9 and a resin.

[0191] (Configuration 12) A coating film comprising the heat-shielding pigment according to any one of Configurations 1 to 9 and a resin, wherein an average inclination of the heat-shielding pigment with respect to the air-side surface of the coating film is 20° or less.

[0192] (Configuration 13) A coating film comprising the heat-shielding pigment and a resin according to any one of Configurations 1 to 9, wherein an abundance ratio of the heat-shielding pigment in the vicinity of an air-side surface of the coating film is 1.10 times or more greater than an abundance ratio of the heat-shielding pigment in a central portion of the coating film.

[0193] (Configuration 14) A mobile object provided with a coating film containing the heat-shielding pigment according to any one of Configurations 1 to 9 and a resin.

[0194] (Configuration 15) A building provided with a coating film containing the heat-shielding pigment according to any one of Configurations 1 to 9 and a resin.

[0195] (Method 1) A method for producing a heat-shielding pigment having a layered structure including a conductive layer and a dielectric layer, the method including: a step of depositing a dielectric material on a base material to form a dielectric layer; a step of depositing a conductive material on the dielectric layer to form a conductive layer; a step of coating a surface of a laminate of the dielectric layer and the conductive layer provided on the base material with an organic compound; and a step of peeling the laminate coated with the organic compound from the base material and pulverizing the laminate.

[0196] (Method 2) The method for producing a heat-shielding pigment according to Method 1, further comprising the step of pulverizing the laminate and then coating the pulverized laminate with an organic compound.

[0197] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention.

[0198] This application claims priority based on Japanese Patent Application No. 2024-146726 filed on August 28, 2024 and Japanese Patent Application No. 2025-131575 filed on August 6, 2025, the entire contents of which are incorporated herein by reference.

[0199] 1 heat-shielding pigment 2 conductive layer 3 dielectric layer 4 organic compound

Claims

1. A heat-shielding pigment having a flat plate-like structure with a particle size of 0.50 μm or more and 100 μm or less, the heat-shielding pigment having a laminated structure formed including a conductive layer and a dielectric layer adjacent to each other, wherein at least one surface of the laminated structure is coated with an organic compound, and the amount of the organic compound coated on one surface of the laminated structure is greater than the amount of the organic compound coated on the other surface.

2. The solubility parameter of the organic compound is 20 (J / cm ３ ) １／２ 2. The heat-shielding pigment according to claim 1, wherein:

3. The heat-shielding pigment according to claim 1, wherein the organic compound is an organic compound containing a substituted or unsubstituted hydrocarbon group having 2 to 30 carbon atoms, and at least one functional group selected from the group consisting of an amino group, a hydroxy group, a carboxy group, a phosphate group, and a sulfo group.

4. The heat-shielding pigment according to claim 3, wherein the organic compound is a comb-shaped dispersant having at least one functional group selected from the group consisting of an amino group, a hydroxy group, a carboxy group, a phosphate group, and a sulfo group in its main chain, and a substituted or unsubstituted hydrocarbon group having 2 to 30 carbon atoms in its side chain.

5. The heat-shielding pigment according to claim 1, wherein the organic compound comprises at least one polymer selected from the group consisting of polyvinyl alcohol, acetalized polyvinyl alcohol, polyethylene copolymer, ethylene-vinyl acetate copolymer, and ethylene-acrylic acid copolymer.

6. The heat-shielding pigment according to claim 1, wherein the weight ratio of the coating amount of the organic compound on one surface of the laminated structure to the coating amount on the other surface is 1.20 or more.

7. The heat-shielding pigment according to claim 1, characterized in that the laminated structure is formed by one conductive layer and one dielectric layer adjacent to each other, the conductive layer is made of silver or an alloy containing 50 mass % or more of silver, and has a physical film thickness of 5.0 nm or more and 35 nm or less, the dielectric layer is made of a dielectric material having an average refractive index of 1.70 or more in the wavelength range of 300 nm or more and 800 nm or less, and the optical film thickness of the dielectric layer is 0.50 D or more and 20 D or less, where D [nm] is the physical film thickness of the conductive layer.

8. The heat-shielding pigment according to claim 1, characterized in that the laminated structure is formed by at least three optical functional layers, a first optical functional layer of the laminated structure is made of silver or an alloy containing 50% by mass or more of silver, and has a physical film thickness of 5.0 nm or more and 35 nm or less, a second optical functional layer adjacent to the first optical functional layer is made of a dielectric material having an average refractive index of 1.70 or more in the wavelength range of 300 nm to 800 nm, a third optical functional layer adjacent to the second optical functional layer is made of silver or an alloy containing 50% by mass or more of silver, and has a physical film thickness of 5.0 nm or more and 35 nm or less, and the optical film thickness of the second optical functional layer is 4.0 D or more and 12 D or less, where D [nm] is the sum of the physical film thicknesses of the first optical functional layer and the third optical functional layer.

9. The heat-shielding pigment according to claim 1, wherein the thickness of the heat-shielding pigment is 100 nm or less.

10. A heat-shielding paint comprising the heat-shielding pigment according to any one of claims 1 to 9, an organic solvent, and a resin.

11. A coating film comprising the heat-shielding pigment according to any one of claims 1 to 9 and a resin.

12. A coating film comprising the heat-shielding pigment according to any one of claims 1 to 9 and a resin, wherein the average inclination of the heat-shielding pigment relative to the air-side surface of the coating film is 20° or less.

13. A coating film comprising a heat-shielding pigment and a resin according to any one of claims 1 to 9, characterized in that the abundance ratio of the heat-shielding pigment in the vicinity of the air-side surface of the coating film is 1.10 times or more the abundance ratio of the heat-shielding pigment in the center of the coating film.

14. A mobile object provided with a coating film containing the heat-shielding pigment according to any one of claims 1 to 9 and a resin.

15. A building provided with a coating film containing the heat-shielding pigment according to any one of claims 1 to 9 and a resin.

16. A method for producing a heat-shielding pigment having a laminated structure including a conductive layer and a dielectric layer, the method comprising: a step of depositing a dielectric material on a substrate to form a dielectric layer; a step of depositing a conductive material on the dielectric layer to form a conductive layer; a step of coating a surface of a laminate of the dielectric layer and the conductive layer provided on the substrate with an organic compound; and a step of peeling the laminate coated with the organic compound from the substrate and pulverizing the laminate.

17. The method for producing a heat-shielding pigment according to claim 16, further comprising the step of pulverizing the laminate and then coating the pulverized laminate with an organic compound.

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