Coating film, ink or coating material, and composite laminate

Abstract

Provided is a coating film or the like that can improve heat radiation efficiency and / or heat absorption efficiency of an object to be treated.　Provided is a coating film containing at least one kind of inorganic particle and being formed on an object to be treated. The coating film is characterized by having a light absorption rate of 30% or more at the maximum absorption wavelength in a wavelength range of 780-25000 nm, a heat capacity smaller than that of the object to be treated, and a ratio of 5% or more of an overlapping area α, in which a radiation peak in the radiation spectrum 2 of the object to be treated at a first specific temperature overlaps an absorption peak in an absorption spectrum 1 of the coating film when both the radiation peak and the absorption peak are respectively standardized by the maximum values, over the area β of the whole radiation peak. This composite laminate is characterized by comprising: a substrate having a colored surface having a light absorption rate of 30% or more at the maximum absorption wavelength in the wavelength range; and a translucent coating film for coating the colored surface of the substrate, wherein the light reflectance is 30% or more at the maximum reflection wavelength in the wavelength range when light is emitted from the surface side.

Description

Coatings and inks or paints and composite laminates

[0001] The present invention relates to coatings and inks or paints and composite laminates.

[0002] In modern society, thermal management is important for buildings, vehicles such as automobiles, electronic devices, etc. Construction companies, building material manufacturers, automobile manufacturers, electronic component manufacturers, and other companies are required to develop technologies to control heat, and temperature control technologies that meet these demands have been studied for some time.

[0003] The temperature of buildings, electronic devices, etc. can be controlled to some extent by applying a paint selected from various paints having thermal properties such as heat dissipation, heat absorption, and heat insulation to, for example, the exterior walls of buildings or the housings of electronic devices (treated objects). If the coating film formed by the paint has properties such as heat insulation and heat exchange, the heat dissipation efficiency and heat absorption efficiency of the treated objects constituting the buildings, etc. can be improved, and heat accumulation prevention effects and temperature raising and lowering effects can be achieved. For example, temperature rise due to heat absorption occurs not only through heat transfer between materials associated with thermal conduction and convection, but also through radiant heat from heat sources such as sunlight. However, adjusting the radiant heat absorption efficiency with a coating film can promote temperature rise and lowering. In addition to heat absorption, coating films having heat-shielding, light-shielding, and light-absorbing properties can also be used to control the temperature of buildings, moving objects (e.g., vehicles such as automobiles and trains), electronic devices, etc.

[0004] For example, Patent Document 1 discloses an infrared emitting / absorbing paint containing a solid solution powder of three or more transition metal element oxides that exhibits high infrared spectral emissivity. Patent Document 2 describes a thermally emissive surface treatment agent containing specific amounts of carbon black and titania and having a thermal emissivity of 60% or more. Patent Document 3 also discloses a heat-dissipating paint composition containing specific amounts of an infrared-absorbing binder resin and infrared-absorbing inorganic particles, each of which has a specific infrared absorption spectrum.

[0005] The temperature of vehicles, buildings, etc. can also be controlled by coating a member (object to be treated) such as a metal body, housing, etc. For example, Patent Document 4 discloses a cooling film having a light-reflecting layer of silver or a silver alloy and a vapor-deposited layer of indium or tin.

[0006] Japanese Patent Application Laid-Open No. 61-64765 Japanese Patent Application Laid-Open No. 2002-226783 Japanese Patent No. 5475932 Japanese Patent Application Laid-Open No. 2023-144729

[0007] Conventional techniques, including those disclosed in Patent Documents 1 to 3, have attempted to improve heat dissipation performance by using inorganic particles with higher heat dissipation performance than the components (workpieces) that make up various devices, such as housings for electrical, electronic, and optical devices. However, these techniques may be limited to certain workpieces. Furthermore, attempts to control the temperature of the workpiece by at least one of lowering, maintaining, and raising the temperature do not necessarily produce sufficient results.

[0008] Furthermore, conventional temperature control technologies often do not take translucency into consideration. For example, the surface treatment agent described in Patent Document 2 contains carbon black, which may change the hue of the coated substrate or cause a loss of transparency, thereby impairing the appearance. The cooling film described in Patent Document 4 utilizes a design based on a silver or silver alloy light-reflecting layer, but does not include the technical idea of ​​maintaining the appearance of the substrate surface with a translucent light-reflecting layer. Therefore, conventional technologies have also had the problem of sacrificing the original appearance of the substrate when controlling the temperature of the substrate.

[0009] In order to solve the above-mentioned problems, an object of the present invention is to provide a coating that can be applied to various types of workpieces to improve their heat dissipation efficiency and / or heat absorption efficiency, and can cause at least one of temperature conditions of decreasing, maintaining, and increasing the temperature of the workpiece. Another object of the present invention is to provide an ink or paint used to form the coating, and a composite laminate including the workpiece and the coating. Still another object of the present invention is to provide a composite laminate having a coating made of a light-transmitting material (light-transmitting surface coating material) on the surface of a substrate, and that can suppress temperature rise of the coated substrate.

[0010] The present inventors have discovered that by forming a coating on a workpiece that exhibits strong absorption in the infrared range and has an absorption spectrum that overlaps with the radiation spectrum of the workpiece or the radiation spectrum of a heat source, the heat dissipation efficiency and / or heat absorption efficiency of the workpiece can be improved, and that at least one of a temperature drop, maintenance, and increase in the temperature of the workpiece can be achieved, and that the heat dissipation efficiency can be further increased by making the heat capacity of the coating smaller than that of the workpiece, thereby completing the present invention.The present inventors have also discovered that a light-transmitting coating film with a reflectance of 30% or more for light at a specific wavelength can suppress temperature increases in a specific substrate.

[0011] That is, the present invention provides the following (1) to (24): (1) A coating containing at least one type of inorganic particles and formed on a workpiece, wherein the coating has a light absorptance of 30% or more at an absorption maximum wavelength in a wavelength range of 780 to 25,000 nm, the coating has a smaller heat capacity than the workpiece, and the ratio of an overlapping area of ​​a radiation peak in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating, when both peaks are normalized by their maximum values ​​at a first specific temperature, to the total area of ​​the radiation peaks is 5% or more (Coating-1). (2) A coating containing at least one type of inorganic particles and formed on a workpiece, the coating having a light absorptance of 30% or more at a maximum absorption wavelength in a wavelength range of 780 to 25,000 nm, and characterized in that, at a second specific temperature, the ratio of an overlapping area of ​​an emission peak in the emission spectrum of a heat source radiating heat rays to the workpiece and an absorption peak in the absorption spectrum of the coating, when both peaks are normalized by their maximum values, to the total area of ​​the emission peaks is 5% or more (Coating-2). (3) A coating containing at least one type of inorganic particles and formed on a workpiece, wherein the coating has a light absorptance of 30% or more at a maximum absorption wavelength in a wavelength range of 780 to 25,000 nm, and at the upper limit temperature of a third specific temperature range, a ratio of an overlapping area where a radiation peak in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating overlap when both are normalized by their maximum values ​​to the total area of ​​the radiation peaks is 5% or more, and at the lower limit temperature of the third specific temperature range, a ratio of an overlapping area where a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the workpiece and an absorption peak in the absorption spectrum of the coating overlap when both are normalized by their maximum values ​​to the total area of ​​the radiation peaks is 5% or more (Coating-3). (4) The coating according to any one of (1) to (3) above, wherein the light reflectance at the maximum reflection wavelength in the wavelength range of 780 to 25,000 nm is 40% or more and 70% or less. (5) The coating according to any one of (1) to (4) above, wherein the inorganic particles have an average particle size in the range of 1 nm to 100 μm.(6) The coating of any of (1) to (5) above, wherein the inorganic particles comprise one or more types of particles selected from the group consisting of degenerate semiconductors, semimetals, and Mxene. (7) The coating of any of (1) or (4) to (6) above, wherein the first specific temperature is in the range of -30°C or higher and lower than 200°C. (8) The coating of any of (1) or (4) to (6) above, wherein the first specific temperature is in the range of 200°C or higher and lower than 1000°C. (9) The coating of any of (2) or (4) to (6) above, wherein the second specific temperature is in the range of -60°C or higher and lower than 40°C. (10) The coating of any of (2) or (4) to (6) above, wherein the second specific temperature is in the range of 40°C or higher and lower than 200°C. (11) The coating of any of (3) to (6) above, wherein the third specific temperature range has an upper limit temperature within a range of -30°C or higher and lower than 200°C, and a lower limit temperature within a range of -60°C or higher and lower than 40°C. (12) The coating of any of (3) to (6) above, wherein the third specific temperature range has an upper limit temperature within a range of 200°C or higher and 1000°C or lower, and a lower limit temperature within a range of 40°C or higher and 200°C or lower. (13) The coating of any of (1) to (12) above, wherein the object to be treated is concrete, stone, wood, glass, ceramic, metal, a metal-coated object, a metal-deposited object, or a resin. (14) An ink or paint containing the inorganic particles and a binder, which is used to form the coating of any of (1) to (12) above. (15) A composite laminate comprising the workpiece and any of the coatings according to (1) to (13) above, laminated directly or indirectly on the surface of the workpiece via an intermediate layer. (16) A composite laminate comprising: a substrate having a colored surface with a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and a light-transmitting coating film made of a light-transmitting material and covering the colored surface of the substrate, wherein when light is irradiated from the surface side of the light-transmitting coating film toward the composite laminate, the light reflectance at the maximum reflection wavelength in the wavelength range of 780 to 25,000 nm is 30% or more. (17) The composite laminate of (16) above, wherein when light is irradiated from the surface side of the light-transmitting coating film toward the composite laminate, the light reflectance at the maximum reflection wavelength is 40% or more and 99% or less.(18) The composite laminate of (16) or (17) above, wherein, when light is irradiated toward the composite laminate from the surface of the light-transmitting coating film, the light reflectance at the reflection maximum wavelength is greater than the light absorptance of the colored surface at the absorption maximum wavelength. (19) The composite laminate of any of (16) to (18) above, wherein, when light is irradiated toward the composite laminate from the surface of the light-transmitting coating film, the number of absorbed photons in a wavelength range of 780 to 25,000 nm is smaller than the number of absorbed photons in said wavelength range of the colored surface. (20) The composite laminate of any of (16) to (19) above, wherein, when light is irradiated toward the composite laminate from the surface of the light-transmitting coating film, the number of reflected photons in a wavelength range of 780 to 25,000 nm is greater than the number of reflected photons in said wavelength range of the colored surface. (21) The composite laminate of any of (16) to (20) above, wherein, when light is irradiated from the surface of the light-transmitting coating film toward the composite laminate, the light reflectance at the maximum reflection wavelength is greater than the light reflectance of the colored surface at the maximum reflection wavelength in a wavelength range of 780 to 25,000 nm. (22) The composite laminate of any of (16) to (21) above, wherein the substrate is made of metal, a metal-coated material, a metal-deposited material, glass, resin, wood, concrete, stone, or ceramic. (23) The composite laminate of any of (16) to (22) above, wherein the light-transmitting coating film contains one or more inorganic particles selected from the group consisting of doped semiconductors, degenerate semiconductors, semimetals, and Mxene. (24) The composite laminate according to (15) above, further comprising a light-transmitting coating film, wherein the coating film has a colored surface having a light absorptance of 30% or more at a maximum absorption wavelength in a wavelength range of 780 to 25,000 nm, the light-transmitting coating film is made of a light-transmitting material and covers the colored surface of the coating film, and when light is irradiated from the surface side of the light-transmitting coating film toward the composite laminate, the light reflectance at a maximum reflection wavelength in a wavelength range of 780 to 25,000 nm is 30% or more.

[0012] The coating of the present invention can be applied to various types of workpieces, and can have the remarkable effect of improving the heat dissipation efficiency and / or heat absorption efficiency of the workpieces, and generating at least one of the temperature states of decreasing, maintaining, and increasing the temperature of the workpieces.

[0013] For example, by applying the above-mentioned Coating-1, it is possible to increase the heat dissipation efficiency and lower the temperature of the workpiece. Furthermore, by applying the above-mentioned Coating-2, it is possible to increase the heat absorption efficiency of the workpiece at a specific temperature, thereby achieving a heat retention effect. Furthermore, by applying the above-mentioned Coating-3, it is possible to increase both the heat dissipation efficiency and the heat absorption efficiency and to control the temperature of the workpiece within a specific temperature range.

[0014] According to one aspect of the composite laminate, which is yet another embodiment of the present invention, the composite laminate has a translucent coating film made of a translucent material with high light reflectance, which has the remarkable effects of maintaining the original appearance of the substrate and suppressing temperature rise in the coated substrate.

[0015] 1 is a diagram for explaining the overlap area between an absorption peak in the absorption spectrum of a coating according to the present invention and a radiation peak in the radiation spectrum of a workpiece or a radiation peak in the radiation spectrum of a heat source.

[0023] FIG. 1 is a diagram for explaining the temperature measurement means and the points at which temperatures were measured in Examples 1 to 6 and Comparative Examples 1 and 2 according to the present invention.

[0024] FIG. 1 is a graph showing the change in temperature over time at measurement point B shown in FIG. 2 in Examples 1 to 6 and Comparative Examples 1 and 2 according to the present invention.

[0025] FIG. 1 is a graph showing the change in temperature over time at measurement point D shown in FIG. 2 in Examples 1 to 6 and Comparative Examples 1 and 2 according to the present invention.

[0026] FIG. 1 is a graph showing the radiation spectrum of a workpiece in Example 9 according to the present invention, plotting the degree of temperature drop (K) when the temperature of a plurality of composite laminates formed with coatings having different absorption peaks is dropped relative to the temperature of the workpiece.

[0016] The present invention will be described in detail below based on several embodiments, but the present invention is not limited to these embodiments.

[0017] <Coating-1> This embodiment is a coating that contains at least one type of inorganic particle and is formed on a workpiece, the coating having a light absorptance of 30% or more at a maximum absorption wavelength in a wavelength range of 780 to 25,000 nm, a small heat capacity compared to the workpiece, and a ratio of an overlapping area of ​​a radiation peak in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating, when both are normalized by their maximum values, to an area of ​​the entire radiation peak, of 5% or more.

[0018] Here, "a coating formed on a substrate" refers to a film-like substance formed on a substrate such as a building or a vehicle. A typical example is a coating obtained by applying and drying ink or paint, i.e., a coating film, but is not limited to these. The coating of this embodiment may be, for example, a film, sheet, or board (plate-like object) that can be adhered or fused to the substrate, and in a broader sense, includes all materials that can be formed on the substrate, such as inks and paints for forming coatings. Coating-1 can be in any form as long as it is defined in the present invention.

[0019] In addition to the aforementioned buildings and vehicles (mobile objects), examples of substrates on which Coating-1 of this embodiment can be formed include, but are not limited to, heating furnaces, electrical and electronic equipment, and parts and components used therein, such as building materials, vehicle parts, furnace materials, engines, engine peripherals, electrical and electronic equipment, and their components and housings, as well as materials such as concrete, stone, wood, glass, ceramic, metals including metal-coated and metal-deposited products, and resins. Building materials, for example, may be made of concrete or may be composites of stone, glass, ceramic, etc. Ceramic building materials, specifically ceramic building materials, such as roof tiles, may also be used. Furthermore, vehicles, for example, may be parts such as painted metal plates or metal-deposited resins.

[0020] The "first specific temperature" is a temperature that serves as a guideline for the upper limit temperature of the target object to be treated. For example, if the coating-1 of this embodiment is formed on an object to be treated, such as a building, the temperature of the object to be treated rises due to direct sunlight, etc., and around the first specific temperature, the radiation spectrum of the object to be treated and the absorption spectrum of the coating-1 overlap, accelerating heat transfer from the object to the coating-1. Furthermore, since the light absorption rate of the coating-1 at its maximum absorption wavelength in the wavelength range of 780 to 25,000 nm is 30% or more, it easily absorbs radiant heat from the object to be treated, while the radiant heat emitted to the object to be treated is small. Furthermore, since the heat capacity of the coating-1 is smaller than that of the object to be treated, heat transferred to the coating-1 is efficiently released. As a result, the formation of the coating-1 facilitates a decrease in the temperature of the object to be treated.

[0021] (Light Absorbance) As described above, Coating-1 has a light absorbance of 30% or more at the absorption maximum wavelength in the wavelength range of 780 to 25,000 nm. Here, the light absorbance (%) can be calculated by subtracting the intensity of transmitted light and reflected light from the intensity of incident light, then dividing by the intensity of incident light and multiplying the result by 100. Because light with wavelengths of 780 to 25,000 nm roughly corresponds to near-infrared to far-infrared light, the light absorbance at the absorption maximum wavelength in this wavelength range is roughly synonymous with the maximum value of infrared light absorbance. Therefore, the light absorbance can be measured, for example, using a general-purpose infrared spectrometer or infrared camera. The maximum value of light absorbance can be measured from the measured infrared absorption spectrum. If the wavelength at the absorption maximum is known, the light absorbance at the absorption maximum wavelength can also be measured using a photometer.

[0022] In this embodiment, the light absorptance of Coating-1 in the wavelength range of 780 to 25,000 nm is preferably 35% or more, more preferably 40% or more, even more preferably 45% or more, and particularly preferably 50% or more. There is no particular upper limit to the light absorptance, and it may be 100%, but considering the characteristics of existing materials, it may be 80%, 70%, or 60%, for example.

[0023] When Coating-1 of this embodiment is applied to the outer surface of a wall material (subject to be treated) such as concrete that constitutes a building or the like, the higher the reflectance, the better from the viewpoint of preventing a rise in temperature due to heat absorption, and for example, it is preferable that the maximum value of reflectance in the wavelength range of 780 to 25,000 nm is 40% to 70%, more preferably 45% to 65%, and particularly preferably 50% to 60%, etc. In addition, in each substance including Coating-1, when light transmittance can be ignored, the relationship of light absorptance ≒ emissivity ≒ 100 - reflectance (both in %) holds.

[0024] <Inorganic Particles> The property of having a light absorptance of 30% or more at the absorption maximum wavelength in the wavelength range of 780 to 25,000 nm can be achieved, for example, by including at least one type of inorganic particle having a light absorptance of 30% or more at the absorption maximum wavelength in the same wavelength range in Coating 1. Examples of inorganic particles having a light absorptance of 30% or more include, but are not limited to, particles of degenerate semiconductors, doped semiconductor materials, non-degenerate semiconductor materials, semimetals, and Mxene.

[0025] Here, degenerate semiconductors are also called heavily doped semiconductors, and specific examples thereof include tin-doped indium oxide (ITO), aluminum-doped indium oxide, cerium-doped indium oxide, antimony-doped indium oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), indium-doped cadmium oxide, indium-fluoride-doped cadmium oxide, fluorine-doped cadmium oxide, chlorine-doped cadmium oxide, bromine-doped cadmium oxide, cesium-doped molybdenum oxide, antimony-doped tin oxide, fluorine-doped tin oxide, titanium oxide, copper sulfide, copper phosphide, copper telluride, copper selenide, ruthenium oxide, rhenium oxide, molybdenum oxide, tungsten oxide, tungsten bronze, nickel sulfide, and CuWS. ４ , tungsten-doped TiO ２ , molybdenum-doped TiO ２ , Bi ２ WO ６ The following can be mentioned:

[0026] Semimetals are metalloids consisting of bismuth, antimony, graphite, silicon, boron, etc. Mxene is a metalloid consisting of Ti, ３ C ２ , Mo ２ TiC ２ , Mo ２ Ti ２ C ３ , Cr ２ TiC ２ and the like.

[0027] Films containing these inorganic particles typically have a maximum light absorptance of 30% or more, often 40% or more, and particularly 60% or more, in the wavelength range of 780 to 25,000 nm, making it easy to achieve a light absorptance of 30% at the absorption maximum wavelength of Coating-1. Furthermore, heat emitted (radiated) or absorbed by the object to be treated can be efficiently transferred to Coating-1 containing inorganic particles, potentially improving the heat dissipation efficiency of the object. Furthermore, when these inorganic particles are incorporated into a coating, it becomes easy to adjust the absorption spectrum of the coating so that it overlaps with the radiation spectrum of the object to be treated in an appropriate wavelength range.

[0028] (Emissivity) In Coating-1 of this embodiment, it is preferable that the emissivity of the inorganic particles is smaller than that of the object to be treated. If the emissivity of the inorganic particles is smaller than that of the object to be treated, the radiant heat radiated from Coating-1 to the object to be treated will also be smaller, making it easier for the temperature of the object to be treated to drop. Conventional heat-dissipating paints and the like have generally used inorganic particles made of a material with higher heat dissipation performance than the object to be treated. However, in this case, an unexpected effect was obtained in that high heat dissipation efficiency can be achieved even when inorganic particles made of a material with a lower emissivity, which is a measure of heat dissipation performance, than the object to be treated are used.

[0029] The inorganic particles exemplified above also have the advantage that their emissivity is generally lower than that of the treated material, such as concrete, iron, etc. For example, the light absorptance≒emissivity (emissivity) at room temperature is typically about 70-95% for concrete, about 58% for AZO, about 30-36% for iron and stainless steel, about 21% for ITO, about 10-23% for aluminum powder, and about 3-6% for copper powder.

[0030] Emissivity is the ratio of the energy emitted by radiation from an object at a certain temperature divided by the energy emitted by a blackbody at the same temperature, and is also referred to as "emissivity." Because this value varies significantly depending on wavelength and temperature, in this embodiment, the maximum value in the wavelength range of 780 to 25,000 nm (or the maximum value of multiple peaks in the same wavelength range) is used as the "emissivity." It can be measured, for example, by FT-IR, thermography, or other methods. From the perspective of heat transfer from the object to be treated to Coating-1 and heat dissipation efficiency, it is preferable to use the emissivity at the first specific temperature, in other words, the temperature at which heat transfer begins to be promoted, as the reference. However, for the purpose of comparing the magnitude relationship of the emissivity between Coating-1 and the object to be treated, the value at room temperature can be used instead. This also applies to the optical absorptivity described above, as well as the specific heat, etc., described below.

[0031] In Coating-1 of this embodiment, the emissivity of the inorganic particles is preferably 1 / 1.05 or less, more preferably 1 / 1.1 or less, even more preferably 1 / 100 to 1 / 1.2, and particularly preferably 1 / 5 to 1 / 1.5, when the emissivity of the object to be treated is taken as 1 (reference).

[0032] (Examples of inorganic particles) The inorganic particles may also be surface-treated or the like. The inorganic particles may also be composites of multiple materials in the form of a core-shell structure, a heterostructure, or the like. In this embodiment, the type of inorganic particles may be one type, or two or more types may be used in combination. For example, one type or two or more types of inorganic particles exhibiting specific light absorptance and emissivity may be selected, or inorganic particles exhibiting specific light absorptance and emissivity may be used in combination with other inorganic particles.

[0033] The inorganic particles are degenerate semiconductors (heavily doped semiconductors) having absorption in the infrared region, such as tin-doped indium oxide, aluminum-doped indium oxide, cerium-doped indium oxide, antimony-doped indium oxide (ATO), aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, indium-doped cadmium oxide, fluorine-doped indium oxide, fluorine-doped cadmium oxide, chlorine-doped cadmium oxide, bromine-doped cadmium oxide, cesium-doped molybdenum oxide, antimony-doped tin oxide, fluorine-doped tin oxide, titanium oxide, copper sulfide, copper phosphide, copper telluride, copper selenide, ruthenium oxide, rhenium oxide, molybdenum oxide, tungsten oxide, tungsten bronze, nickel sulfide, CuWS ４ , tungsten-doped TiO ２ , molybdenum-doped TiO ２ , Bi ２ WO ６ It is preferable that the particle contains one or more types of particles selected from the group consisting of degenerate semiconductors such as ZnO, semimetals, and Mxene.

[0034] These inorganic particles have a maximum light absorptivity of 30% or more, often 40% or more, and particularly 60% or more, in the wavelength range of 780 to 25,000 nm. Furthermore, their emissivity is generally lower than that of treated objects such as concrete and iron. Furthermore, when these inorganic particles are incorporated into a coating, it becomes easy to adjust the absorption spectrum of the coating so that it overlaps with the radiation spectrum of the treated object in an appropriate wavelength range. As described below, if the specific heat of the inorganic particles in Coating-1 is lower than that of the treated object, the heat capacity of the coating also becomes smaller, facilitating heat dissipation after heat transfer from the treated object to the inorganic particles, thereby enabling more efficient heat dissipation. To increase the reflectivity of Coating-1, inorganic particles with a reflectivity of, for example, about 40 to 80%, particularly about 50 to 70%, may be used.

[0035] (Particle size of inorganic particles) There are no particular limitations on the particle size of the inorganic particles, and inorganic particles with any average particle size and particle size distribution can be used. Preferably, nanoparticles, for example, inorganic particles with an average particle size in the range of 1 nm to 100 μm, particularly 5 nm to 100 nm, are used. Here, "average particle size" refers to the average diameter of primary particles measured by observation with a transmission electron microscope or dynamic light scattering, particularly the former. Because such nanoparticles have a large surface area relative to their mass, they facilitate heat transfer between the workpiece and the surrounding environment, further improving heat dissipation efficiency.

[0036] <Binder> Coating-1 of this embodiment preferably contains a binder along with the inorganic particles. There are no particular limitations on the type of binder, and various known binders can be used. Examples include, but are not limited to, various resins and elastomers (organic polymers) such as polyvinyl acetate, poly(meth)acrylic acid (ester), aliphatic polyester, aromatic polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyamide, polyurethane, polyimide, epoxy resin, phenolic resin, silicone resin, fluororesin, polyphenylene oxide, polyphenylene sulfide, polyether sulfone, polyether ketone, polyacrylonitrile, polystyrene, polyester, polypropylene, ABS resin, polyvinyl butyral, styrene-butadiene copolymer, and nitrile-butadiene copolymer, as well as inorganic binders such as cement. Condensates of alkoxysilanes, silanols, and the like can also be used as binders. Small molecules with multiple coordination sites, such as ethanedithiol, succinic acid, and ethylenediamine, and photopolymerizable compounds can also be used as binders. Diamond-like carbon or the like can also be used as a binder.

[0037] <Coating Preparation> Coating-1 of this embodiment can be prepared, for example, by mixing the inorganic particles and binder described above and then molding the mixture. There are no particular limitations on the mixing ratio between the two, and a desired ratio can be selected depending on the type of treatment agent to be applied, the environment in which it is used, and the desired first specific temperature. For example, the inorganic particles:binder mass ratio may be, but is not limited to, 0.001 to 99:99.999 to 1, particularly 0.05 to 30:99.95 to 70. The thickness of the coating is also not particularly limited, and can be, for example, 10 nm to 10 mm, preferably 20 nm to 500 μm, and particularly 100 nm to 100 μm, depending on the purpose and application area. In other words, Coating-1 of this embodiment encompasses not only thin-film coatings but also sheet- or board-shaped membranes. When Coating-1 is a coating, the thickness after drying is preferably, for example, 20 nm to 1 μm, particularly 100 to 500 nm.

[0038] The mixing method is not particularly limited; for example, a thermoplastic resin such as polyethylene or polypropylene may be melt-kneaded with inorganic particles. For example, a sheet-shaped coating-1 can be prepared by kneading the two materials in an extruder and simultaneously extruding them into a sheet. When using a liquid polymer such as some epoxy resins or unsaturated polyesters as a binder, it may be mixed with inorganic particles at room temperature and then cured. Alternatively, various polymers such as polyester or silicone may be mixed with inorganic particles in a solvent and applied to the substrate as an ink or paint. Here, instead of a polymer, a monomer such as alkoxysilane or silanol may be used, and after mixing with inorganic particles or after mixing and applying to the substrate, the mixture may be condensed to form a binder.

[0039] (Ink / Paint) In this embodiment, it is preferable to mix inorganic particles and a binder in a solvent to form an ink or paint, which is then applied to a substrate to form a coating. The present invention encompasses inks and paints containing the inorganic particles and binder described above. In the form of an ink or paint, the coating of this embodiment can be easily applied to, for example, recessed areas, according to the shape of a building or vehicle. Furthermore, by overcoating other inks or paints, it is easy to impart multiple functions, such as heat dissipation and aesthetics, to the substrate.

[0040] The solvent is not particularly limited, and any solvent may be used as long as it can dissolve the polymer, monomer, etc. used. Examples include, but are not limited to, alcohols such as ethanol and propanol; ethers such as tetrahydrofuran and dioxane; cellosolves such as methyl cellosolve and butyl cellosolve; ketones such as acetone and methyl ethyl ketone; hydrocarbons such as toluene and xylene; and water; and mixtures thereof. An ink or paint can be prepared by mixing these inorganic particles, binder, and solvent in a mass ratio of, for example, 0.001 to 99:0.001 to 99:99.998 to 0.999, preferably 0.1 to 20:0.1 to 20:99.8 to 60, particularly 1 to 10:1 to 10:98 to 80.

[0041] While ink and paint are sometimes used synonymously, they are sometimes distinguished by the term "ink" referring to a material primarily intended to enhance the appearance of the substrate, and "paint" referring to a material primarily intended to protect the substrate. In the present embodiment, materials that fall into either of these categories may be used. For example, in addition to inorganic particles and a binder, pigments or dyes for enhancing the appearance may also be included. Other additives commonly used in inks and paints, such as dispersants, surfactants, stabilizers, antioxidants, pH adjusters, and viscosity adjusters, may also be included. When these pigments or additives are used, the amount thereof is preferably, for example, 0.0001 to 90 parts by mass, preferably 0.001 to 50 parts by mass, more preferably 0.01 to 20 parts by mass, and particularly preferably 0.5 to 10 parts by mass, per 100 parts by mass of the inorganic particles and binder combined.

[0042] (Coating film) A coating film (film) can be formed on the surface of the substrate by applying the ink or paint described above to the substrate and evaporating the solvent to dryness. It is also possible to use a photopolymerizable compound as a binder and form a coating film (film) by photopolymerization. Furthermore, a separately formed film or film may be applied to the substrate by adhesion or other methods.

[0043] <Characteristics of Coating-1> As described above, Coating-1 of this embodiment has a light absorptance of 30% or more at the absorption maximum wavelength in the wavelength range of 780 to 25,000 nm, and has a smaller heat capacity than the object to be treated. Coating-1 is also characterized in that, when the radiation peak in the radiation spectrum of the object to be treated and the absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at the target upper limit temperature of the object to be treated, i.e., the first specific temperature, the overlapping area (between the peaks) is 5% or more of the total area of ​​the radiation peaks.

[0044] (Heat Capacity) In this embodiment, the heat capacity of the coating-1 is smaller than that of the object to be treated, so the heat transferred from the object to the coating-1 is efficiently released (radiated) to the surroundings. Note that "heat capacity" refers to the value obtained by multiplying the "specific heat capacity" or "specific heat" of a substance by the mass of that substance. In buildings and the like, coatings generally have a smaller heat capacity than building materials such as concrete due to the difference in mass. Here, by selecting inorganic particles with a smaller specific heat than the object to be treated, it becomes easier to ensure that the heat capacity of the coating-1 is smaller than that of the object to be treated.

[0045] (Specific heat) For example, when the object to be treated is a building mainly made of concrete, which typically has a specific heat of 850 to 1300 J / kg K, it is preferable to select inorganic particles having a specific heat of 800 J / kg K or less, particularly 600 J / kg K or less. When the object to be treated is a vehicle or equipment mainly made of iron, which has a specific heat of 440 to 470 J / kg K, or stainless steel (trademark), which typically has a specific heat of 440 to 500 J / kg K, it is preferable to select inorganic particles having a specific heat of 400 J / kg K or less, particularly 350 J / kg K or less. When the object to be treated is a housing or the like made mainly of various resins, which has a specific heat of about 1000 to 2000, it is also possible to use inorganic particles having a specific heat of 950 J / kg K or less, particularly 900 J / kg K or less.

[0046] Examples of inorganic particles with a specific heat of 950 J / kg K or less include particles of magnesia (924 J / kg K), mica (880 J / kg K), diatomaceous earth (840 J / kg K), calcium carbonate (820 J / kg K), etc.; examples of inorganic particles with a specific heat of 800 J / kg K or less include particles of alumina (779 J / kg K), silica (740 J / kg K), quartz (710 J / kg K), aluminum nitride (738 J / kg K), etc.; and examples of inorganic particles with a specific heat of 600 J / kg K or less include particles of the above-mentioned stainless steel, zirconia (456 J / kg K), zinc oxide (502 J / kg K), AZO (Al-doped ZnO, specific heat: 500 J / kg K), etc., but are not limited to these. Examples of inorganic particles having a specific heat of 400 J / kg·K or less, 350 J / kg·K or less include metal powders such as copper powder (385 J / kg·K), brass powder (380 to 390 J / kg·K), and tin (Sn) powder (226 J / kg·K); semiconductor powders such as ZnSe (360 J / kg·K), CdS (337 J / kg·K), GaAs (325 J / kg·K), LnSb (212 J / kg·K), and CdTe (208 J / kg·K); and further, ITO (Sn-doped In ２ O ３ Specific heat: 340 J / kg·K) and the like, but are not limited to these.

[0047] (Overlap Area) The calculation method for the "overlap area" between the radiation peak in the radiation spectrum of the workpiece and the absorption peak in the absorption spectrum of the coating will be explained using FIG. 1 as an example. First, the absorption peak in the absorption spectrum 1 of the coating and the radiation peak in the radiation spectrum 2 of the workpiece are normalized by the maximum values ​​of both. Specifically, the heights of both peaks are aligned at their maximum values ​​(dashed lines in the upper right corner of FIG. 1) and displayed on a graph of the same wavelength. Here, the "peak" refers to the entire absorption band protruding from the baseline around the peak top. Furthermore, the "height" of the peak refers to the height from the baseline. When displaying on a graph, it is preferable to align the minimum values ​​(dashed lines at the bottom (baseline) in FIG. 1) as well as the maximum values ​​of both peaks. Next, the overlap area α of the overlapping portion between the two peaks, i.e., the radiation peak and the absorption peak, and the area β of the entire radiation peak of the workpiece are measured. The coating-1 of this embodiment is characterized in that the ratio of the overlapping area α of the overlapping portion of both peaks to the area β (100%) of the entire radiation peak is 5% or more. The areas of each peak and the overlapping portion are calculated using the wavelength on the horizontal axis.

[0048] Here, in measuring the overlap area, the "maximum value" refers to the maximum value of the peak in the overlapping range of both spectra. In the example of Figure 1, the peak on the right (longer wavelength side) of the coating's absorption spectrum 1 is smaller than the peak on the left (shorter wavelength side), but because it overlaps with the radiation peak in the radiation spectrum 2 of the treated object, these peak heights are displayed aligned. Furthermore, when multiple peaks appear in the overlapping range, the height of the largest peak among them is taken as the "maximum value." The term "maximum value" is used instead of "local maximum value" because multiple peaks often appear. The "minimum value" refers to the peak height when the absorption or radiation at the base of these peak(s) is essentially zero. Note that the "area of ​​all radiation peaks" refers to the area of ​​all peak(s) in the radiation spectrum of the treated object that overlap with the peak of the coating's absorption spectrum, not the area of ​​the entire spectrum across the entire wavelength range from far-infrared to ultraviolet light.

[0049] If the radiation spectrum of the workpiece overlaps with the absorption spectrum of the coating, the radiant heat of the workpiece is efficiently absorbed by the coating within the wavelength range of the overlap, thereby improving the heat dissipation efficiency of the composite laminate. This accelerates the temperature drop of the workpiece, and also makes it less likely for the composite laminate to experience temperature rise even when exposed to continuous external heat such as direct sunlight. For example, it also becomes easier to control the temperature of the workpiece on which Coating-1 is formed to a temperature below the first specific temperature. The ratio of the overlap area to the total area of ​​the radiation peaks of the workpiece (hereinafter sometimes abbreviated as "overlap ratio") should be 5% or greater, but is preferably 8% or greater, more preferably 10% or greater, even more preferably 12% or greater, even more preferably 15% or greater, and particularly preferably 18% or greater.

[0050] In FIG. 1 , the peak of the absorption spectrum 1 of the coating is located to the left (shorter wavelength side) of the peak of the radiation spectrum 2 of the workpiece, but this embodiment is not limited to this configuration, and the peak of the absorption spectrum may be located to the right (longer wavelength side) of the peak of the radiation spectrum. However, from the viewpoint of heat dissipation efficiency, it is preferable that the absorption peak of the absorption spectrum is located slightly shorter wavelength (higher energy side) than the radiation peak of the radiation spectrum. In a more preferred configuration of this embodiment, the peak top of the absorption spectrum of the coating is located 100 to 10,000 nm shorter wavelength side, particularly 1,000 to 5,000 nm, and more preferably 1,000 to 3,000 nm shorter wavelength side of the radiation peak top in the radiation spectrum of the workpiece. In such a configuration, the overlap ratio is, for example, 50% or more, particularly 70% or more, and heat dissipation is more efficient.

[0051] Here, for example, if the coating-1 is designed so that the overlap ratio is 5% or more when the temperature of the workpiece rises due to sunlight or the like and reaches the first specific temperature, the heat dissipation efficiency after the first specific temperature is reached will be increased, and it will be difficult for the temperature of the workpiece to rise any further. In this way, by applying the coating-1 of this embodiment to the workpiece, it is possible to control the temperature of the workpiece to, for example, about the first specific temperature or below.

[0052] Coating-1 with such an absorption spectrum can be prepared, for example, by selecting the raw materials used as inorganic particles according to the object to be treated as described above. In particular, degenerate semiconductors (heavily doped semiconductors) having absorption in the infrared region, such as tin-doped indium oxide, antimony-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, indium-doped cadmium oxide, fluorine-doped indium oxide, fluorine-doped cadmium oxide, chlorine-doped cadmium oxide, bromine-doped cadmium oxide, cesium-doped molybdenum oxide, antimony-doped tin oxide, fluorine-doped tin oxide, titanium oxide, copper sulfide, copper phosphide, copper telluride, copper selenide, ruthenium oxide, rhenium oxide, molybdenum oxide, tungsten oxide, tungsten bronze, nickel sulfide, and CuWS. ４ , tungsten-doped TiO ２ , molybdenum-doped TiO ２ , Bi ２ WO ６ The present invention can be readily prepared by using inorganic particles including one or more particles selected from the group consisting of: semi-metallic, and Mxene.

[0053] In addition, taking into consideration the temperature of a building or vehicle in the summer and the temperature inside the building or vehicle, it is preferable to set the first specific temperature, for example, between −30° C. and 200° C., and more preferably within the range of 20° C. to 100° C., and particularly within the range of 30 to 50° C. The temperature of the exterior walls of a building or vehicle can reach around 80° C. or higher in the summer, so by setting the first specific temperature to 20 to 100° C., it is possible to suppress the rise in the internal temperature and further reduce the power and costs for air conditioning.

[0054] Furthermore, taking into consideration the temperatures of a furnace, an engine, etc., the first specific temperature can be set to, for example, 200° C. or higher and 1000° C. or lower. More specifically, Coating-1 of this embodiment includes, for example, the coatings described in the following (I) to (IV).

[0055] (I) A coating that contains at least one type of inorganic particle and is formed on a building or construction material; that has a light absorptance of 30% or more at the maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; that has a heat capacity that is smaller than that of concrete or stone; and that, when a radiation peak in the radiation spectrum of the concrete or stone and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at temperatures between -30°C and less than 200°C, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more.

[0056] (II) A coating containing at least one type of inorganic particle and formed on a vehicle (mobile body) such as an automobile or train; characterized in that the coating has a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm, a heat capacity that is smaller than that of the metallic material, and a ratio of the overlap area of ​​the radiation peak in the radiation spectrum of the metallic material and the absorption peak in the absorption spectrum of the coating to the total area of ​​the radiation peaks when both are normalized by their maximum values ​​at temperatures from -30°C to less than 200°C is 5% or more.

[0057] (III) A coating containing at least one type of inorganic particle and formed on a furnace material, an engine, or an engine peripheral part; characterized in that the coating has a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm, a heat capacity that is smaller than that of the constituent material, and the ratio of the overlap area of ​​the radiation peak in the radiation spectrum of the constituent material and the absorption peak in the absorption spectrum of the coating, when both are normalized by their maximum values ​​at 200°C or higher and 1,000°C or lower, to the area of ​​the entire radiation peak, is 5% or higher.

[0058] (IV) A coating containing at least one type of inorganic particle and formed on a component or housing of an electric or electronic device, characterized in that: it has a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; its heat capacity is smaller than that of the constituent material; and the ratio of the overlap area of ​​the radiation peak in the radiation spectrum of the constituent material and the absorption peak in the absorption spectrum of the coating, when both are normalized by their maximum values ​​at temperatures from -30°C to less than 200°C, to the area of ​​the entire radiation peaks, is 5% or more.

[0059] The present invention also encompasses the use of the above-mentioned Coating-1 on objects to be treated that constitute buildings, building materials, vehicles, vehicle parts, furnace materials, engines, engine peripheral parts, or parts or housings of electrical or electronic equipment.

[0060] <<Coating-2>> While the above-described Coating-1 was intended to promote a decrease in the temperature of the workpiece, it is also possible to prepare Coating-2 for the purpose of increasing the temperature of the workpiece. Coating-2 of this embodiment is a coating that contains at least one type of inorganic particles and is formed on the workpiece, characterized in that it has a light absorptance of 30% or more at an absorption maximum wavelength in the wavelength range of 780 to 25,000 nm, and that, when both the radiation peak in the radiation spectrum of the heat source radiating heat rays to the workpiece and the absorption peak in the absorption spectrum of the coating are normalized by their maximum values ​​at a second specific temperature, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more.

[0061] Here, "light absorptance at the absorption maximum wavelength" is as described in the explanation of the light absorptance of Coating-1, and when there are multiple absorption peaks, it refers to the maximum value in the infrared region. Furthermore, the "second specific temperature" is a temperature that serves as a guide for the lower limit temperature of the target object to be treated. For example, if Coating-2 of this embodiment is formed on an object to be treated, such as a building, the radiation spectrum of a heat source, such as direct sunlight, and the absorption spectrum of Coating-2 overlap near the second specific temperature, making it easier for Coating-2 to absorb heat.

[0062] The overlap ratio can be determined in the same manner as for Coating-1. Using the example shown in Figure 1 as an example, the left-hand peak of the coating's absorption spectrum 1 and the radiation peak in the heat source's radiation spectrum 3 are aligned in height from the baseline at their maximum values ​​(dashed lines drawn at the peak top positions in Figure 1), for example, when the maximum and minimum values ​​(dashed lines drawn on the baseline in Figure 1) are aligned, and the overlap area γ between the peaks, i.e., the absorption peak (area) and the radiation peak (area), is determined. The area ratio can be calculated by dividing this by the area δ of all the radiation peaks in the radiation spectrum 3.

[0063] Note that the "area of ​​all radiation peaks" refers to the area of ​​all peaks (groups) in the radiation spectrum of the heat source that overlap with peaks in the absorption spectrum of the coating, and does not refer to the area of ​​the spectrum over all wavelengths from far-infrared light to ultraviolet light. Furthermore, in Figure 1, the left peak of absorption spectrum 1 appears to the right (longer wavelength side) of the peak of radiation spectrum 3 of the heat source, but this embodiment is not limited to this, and the peak of the absorption spectrum may appear to the left (shorter wavelength side) of the peak of the radiation spectrum.

[0064] <Inorganic Particles> Preferred examples of inorganic particles in Coating-2 include inorganic particles containing one or more particles selected from the group consisting of degenerate semiconductors, semimetals, and Mxene. By using such inorganic particles, the light absorptance of Coating-2 at its maximum absorption wavelength in the wavelength range of 780 to 25,000 nm can be easily increased to 30% or more.

[0065] More specifically, degenerate semiconductors (heavily doped semiconductors) having absorption in the infrared region, such as tin-doped indium oxide, aluminum-doped indium oxide, antimony-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, indium-doped cadmium oxide, fluorine-doped indium oxide, fluorine-doped cadmium oxide, chlorine-doped cadmium oxide, bromine-doped cadmium oxide, cesium-doped molybdenum oxide, antimony-doped tin oxide, fluorine-doped tin oxide, titanium oxide, copper sulfide, copper phosphide, copper telluride, copper selenide, ruthenium oxide, rhenium oxide, molybdenum oxide, tungsten oxide, tungsten bronze, nickel sulfide, and CuWS. ４ , tungsten-doped TiO ２ , molybdenum-doped TiO ２ , Bi ２ WO ６ These include, but are not limited to:

[0066] Preferably, tin-doped indium oxide, antimony-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, tungsten-doped TiO ２ , molybdenum-doped TiO ２ , Bi ２ WO ６ The inorganic particles include molybdenum oxide, tungsten oxide, tungsten bronze, etc.

[0067] Coating-2 of this embodiment may contain one type of these inorganic particles, or two or more types. It is also possible to use one or more types of these inorganic particles in combination with one or more types of other inorganic particles. For example, by using multiple types of inorganic particles, particularly nanoparticles, in combination, it is possible to more efficiently capture the radiation spectrum of heat sources such as sunlight. Although some of the inorganic particles described above are exemplified as preferred inorganic particles for Coating-1, these inorganic particles are suitable for both Coating-1 and Coating-2 because their absorption spectra may show multiple peaks, as shown in Figure 1, for example.

[0068] In Coating-2 of this embodiment, it is preferable to use inorganic particles with a higher specific heat than the workpiece. In contrast to Coating-1, by using inorganic particles with a higher specific heat, the coating is less likely to drop in temperature, allowing for more heat to be transferred to the workpiece. Since the specific heat of some of the inorganic particles described above varies depending on the amount of Sn or Al doped, they can also be preferably used in Coating-2 as inorganic particles with a higher specific heat than the workpiece. Furthermore, from the perspective of promoting heat retention through heat absorption, inorganic particles with a reflectance of 60% or less, for example, 1 to 40%, particularly 5 to 20%, in the wavelength range of 780 to 25,000 nm may be used.

[0069] There are no particular restrictions on the particle size of the inorganic particles in Coating 2, but it is preferable to use inorganic particles with an average particle size in the range of 1 nm to 100 μm, particularly 5 nm to 100 nm, similar to the inorganic particles in Coating 1. Such nanoparticles facilitate heat transfer between the coating and the heat source or workpiece, further increasing the temperature rise efficiency.

[0070] <Binder> Coating-2 of this embodiment preferably contains a binder together with the inorganic particles, and the same binder as that used in Coating-1 can be used as this binder.

[0071] <Preparation of Coating> Coating-2 of this embodiment can also be prepared by the same method as Coating-1, for example, using the inorganic particles and binder described above. Coating-2 is also preferably a coating obtained by applying and drying ink or paint, but the composition other than the inorganic particles, such as the type of solvent or additive, and the amount of each component, may be the same as the composition of Coating-1. The method of application to the substrate and the thickness of the coating, particularly the coating or film, may also be the same as for Coating-1.

[0072] <Characteristics of Coating-2> As described above, Coating-2 of this embodiment is characterized in that, when the radiation peak in the radiation spectrum of the heat source and the absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at the lower limit temperature of the target workpiece, i.e., the second specific temperature, the overlapping area of ​​the peaks is 5% or more of the total area of ​​the radiation peaks. In other words, when the radiation peak in the radiation spectrum of the heat source and the absorption peak in the absorption spectrum of the coating are displayed on a graph of the same wavelength with their heights aligned at their maximum values, the overlapping area of ​​the two peaks is 5% or more of the total area of ​​the radiation peaks of the heat source.

[0073] If the ratio of the overlap area to the total area of ​​the radiation peak of the heat source, i.e., the overlap ratio, is 5% or more, the heat absorption efficiency of Coating-2 increases, as described above, making it easier to heat or maintain the temperature of the workpiece. For example, it becomes easier to control the temperature of the workpiece on which Coating-2 is formed to a second specific temperature or higher. The overlap ratio needs only to be 5% or more, but is preferably 8% or more, more preferably 10% or more, even more preferably 12% or more, even more preferably 15% or more, and particularly preferably 18% or more. By applying Coating-2 of this embodiment to the workpiece, it is also possible to control the temperature of the workpiece to, for example, about the second specific temperature or higher.

[0074] When the heat source is sunlight, it is preferable that the coating-2 has an absorption peak near the peak position of the radiation spectrum of sunlight in order to increase the overlap ratio.

[0075] Coating-2 with such an absorption spectrum can be prepared by selecting the raw material used as inorganic particles according to the object to be treated as described above. In particular, tin-doped indium oxide, aluminum-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, tungsten-doped TiO ２ , molybdenum-doped TiO ２ , Bi ２ WO ６The composition can be easily prepared by using inorganic particles containing one or more particles selected from the group consisting of molybdenum oxide, tungsten oxide, tungsten bronze, and the like.

[0076] Although Coating-2 of this embodiment is often used for the purpose of raising the temperature of the workpiece, the reflectance may be increased to prevent excessive temperature rise due to heat absorption. For example, the maximum reflectance in the wavelength range of 780 to 25,000 nm may be 40% to 70%, or even 45% to 65%, or particularly 50% to 60%, etc. Coating-2 with such a reflectance can be produced, for example, by incorporating inorganic particles similar to those exemplified for Coating-1 above.

[0077] In addition, taking into consideration the temperature of buildings and vehicles in winter in cold regions and the temperature inside them, it is preferable that the second specific temperature be set within a range of, for example, −60° C. or higher and lower than 40° C., particularly within a range of −10 to 20° C. By setting the temperature within this range, it is possible to increase or maintain the temperature inside the building or vehicle, and it is also possible to further reduce the power and costs for heating.

[0078] Furthermore, taking into consideration the temperatures of a furnace, an engine, etc., the second specific temperature can be set to, for example, 40° C. or higher and 200° C. or lower. More specifically, coating-2 of this embodiment includes, for example, the coatings described in the following (V) to (VIII).

[0079] (V) A coating that contains at least one type of inorganic particle and is formed on a building or construction material; the coating has a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and when the radiation peak in the radiation spectrum of a heat source that radiates heat rays to concrete or stone that is a constituent material of the building or construction material at a temperature of -60°C or higher but lower than 40°C and the absorption peak in the absorption spectrum of the coating are both normalized by their maximum values, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more.

[0080] (VI) A coating that contains at least one type of inorganic particle and is formed on a vehicle such as an automobile or train; the coating has a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and when the radiation peak in the radiation spectrum of a heat source that radiates heat rays to a metal material that is a component of the vehicle and the absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at temperatures between -60°C and 40°C, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more.

[0081] (VII) A coating containing at least one type of inorganic particle and formed on a furnace material, engine, or engine peripheral part; characterized in that the coating has a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and when the radiation peak in the radiation spectrum of a heat source that radiates heat rays to the constituent material of the furnace material, engine, or engine peripheral part at 40°C to 200°C and the absorption peak in the absorption spectrum of the coating are both normalized by their maximum values, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more.

[0082] (VIII) A coating containing at least one type of inorganic particle and formed on a component or housing of an electric or electronic device; characterized in that the coating has a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and when an emission peak in the emission spectrum of a heat source that radiates heat rays to a component material of the electric or electronic device or housing and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at temperatures of -60°C or higher and lower than 40°C, the ratio of the overlapping area to the total area of ​​the emission peaks is 5% or higher.

[0083] The present invention also encompasses the use of the above-mentioned Coating-2 on objects to be treated that constitute buildings, building materials, vehicles, vehicle parts, furnace materials, engines, engine peripheral parts, or parts or housings of electrical or electronic equipment.

[0084] Coating-3: Coating-1 and Coating-2 are formed on the workpiece to provide a temperature lowering effect and a temperature increasing effect, respectively. By at least partially combining these two, it is possible to maintain the temperature of the workpiece within a specific temperature range.

[0085] Coating-3 of this embodiment is a coating that contains at least one type of inorganic particle and is formed on a workpiece, and is characterized in that it has a light absorptance of 30% or more at an absorption maximum wavelength in a wavelength range of 780 to 25,000 nm, and that, at the upper limit temperature of a third specific temperature range, the ratio of the overlapping area where a radiation peak in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating overlap when both are normalized by their maximum values ​​is 5% or more to the total area of ​​the radiation peaks, and that, at the lower limit temperature of the third specific temperature range, the ratio of the overlapping area where a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the workpiece and an absorption peak in the absorption spectrum of the coating overlap when both are normalized by their maximum values ​​is 5% or more to the total area of ​​the radiation peaks.

[0086] Here, "light absorptance at the absorption maximum wavelength" is as described in the explanation of the light absorptance of Coating-1, and refers to the maximum value when there are multiple absorption peaks. The upper and lower temperature limits of the "third specific temperature range" correspond to the first specific temperature of Coating-1 and the second specific temperature of Coating-2, respectively. The overlap area and its ratio are calculated in the same manner as described for Coating-1 and Coating-2. In the absorption spectrum of Coating-3, the peak that overlaps with the radiation peak of the workpiece and the peak that overlaps with the radiation peak of the heat source may be the same or different.

[0087] As described above, the absorption spectrum of some inorganic particles exhibits peaks at multiple locations, and therefore, for example, coating-3 of this embodiment can be prepared using inorganic particles with a spectrum such as that shown in Figure 1. In this case, it is preferable to use a binder that can be used for coating-1 and coating-2. Note that the relationship between the positions (wavelengths) of the peaks in the absorption spectrum of coating-3, the radiation spectrum of the workpiece, and the radiation spectrum of the heat source is not limited to the example shown in Figure 1. Furthermore, since the absorption spectrum of the same inorganic particles may change depending on the temperature, absorption spectrum 1 in Figure 1 is depicted as being discontinuous at the valleys.

[0088] The inorganic particles may also be a combination of a plurality of particles with different absorption spectra. In the coating-3 of this embodiment, the specific heat of the inorganic particles may be larger or smaller than that of the object to be treated, but by combining inorganic particles having a larger specific heat than that of the object to be treated with inorganic particles having a smaller specific heat than that of the object to be treated, the heat dissipation and / or heat absorption effect may be enhanced.

[0089] A more preferred aspect of Coating-3 of this embodiment is a coating that contains two or more types of inorganic particles and is formed on a workpiece, the inorganic particles including first inorganic particles and second inorganic particles, the first inorganic particles having a lower specific heat capacity than the workpiece, and the second inorganic particles having a higher specific heat capacity than the workpiece, wherein the ratio of the overlapping area of ​​a radiation peak in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating, when both are normalized by their maximum values ​​at the upper limit temperature of a third specific temperature range, to the total area of ​​the radiation peaks is 5% or more, and the ratio of the overlapping area of ​​a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the workpiece and an absorption peak in the absorption spectrum of the coating, when both are normalized by their maximum values, to the total area of ​​the radiation peaks is 5% or more.

[0090] When the coating-3 of this embodiment is applied to the exterior of a building or the like, the reflectance may be increased to prevent a temperature rise due to heat absorption. For example, the maximum value of the reflectance in the wavelength range of 780 to 25,000 nm may be set to 40% or more and 70% or less, further 45% or more and 65% or less, and particularly 50% or more and 60% or less.

[0091] In this embodiment, it is less important that the first inorganic particles, which have a lower specific heat capacity than the object to be treated, have a lower emissivity than the object to be treated. This is because the heat transferred to the first inorganic particles may be transferred to the coexisting second inorganic particles, reducing the radiant heat to the object to be treated. However, from the viewpoint of further improving the heat dissipation efficiency, it is preferable that the emissivity, which is the maximum value in the wavelength range of 780 to 25,000 nm, of the first inorganic particles of Coating-3 is also lower than that of the object to be treated.

[0092] In Coating-3, Coating-1 and Coating-2 or the first and second inorganic particles may be combined in any state. For example, it may be a one-component ink or paint containing one or more types of inorganic particles contained in Coating-1 and one or more types of inorganic particles contained in Coating-2, or a single-layer coating film formed from them. It may also be a two-layer or multi-layer laminate in which a layer of Coating-1 and a layer of Coating-2 are laminated. Furthermore, it is also possible to form a separate structure in which the layer of Coating-1 and the layer of Coating-2 are formed in different locations on the treated object. For example, it is also possible to form a structure in which the treated object is sandwiched between Coating-1 and Coating-2 formed on the front and back surfaces. Coating-3 is particularly preferably a coating film or film, or a laminate thereof, obtained by applying and drying an ink or paint.

[0093] Any materials that can be used as components of Coating-1 and / or Coating-2 can be used as binders for the inorganic particles and optional components contained in Coating-3. The composition other than these components, such as the type of solvent and additives and the amount of each component, may be the same as the composition of Coating-1 and Coating-2. The method of application to the workpiece and the thickness of the coating, particularly the coating, can also be the same as those of Coating-1 and Coating-2. However, it is also preferable to contain two or more types of inorganic particles so that the heat dissipation efficiency and heat absorption efficiency are increased, respectively, at the upper and lower limit temperatures of the temperature control range of the target workpiece, i.e., the third specific temperature range.

[0094] Specifically, a coating containing first inorganic particles including one or more types of particles selected from the group consisting of degenerate semiconductors, semimetals, and Mxene, and second inorganic particles including one or more types of particles selected from the group consisting of inorganic particles that differ from the first inorganic particles in doping amount, crystal form, shape, size, etc., is preferred.

[0095] Examples of degenerate semiconductors (heavily doped semiconductors) having absorption in the infrared region include tin-doped indium oxide, aluminum-doped indium oxide, antimony-doped indium oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, indium-doped cadmium oxide, fluorine-doped indium oxide, fluorine-doped cadmium oxide, chlorine-doped cadmium oxide, bromine-doped cadmium oxide, cesium-doped molybdenum oxide, antimony-doped tin oxide, fluorine-doped tin oxide, titanium oxide, copper sulfide, copper phosphide, copper telluride, copper selenide, ruthenium oxide, rhenium oxide, molybdenum oxide, tungsten oxide, tungsten bronze, nickel sulfide, and CuWS. ４ , tungsten-doped TiO ２ , molybdenum-doped TiO ２ , Bi ２ WO ６ etc. can be used.

[0096] Coating-3, which contains a combination of the first inorganic particles and the second inorganic particles, for example, in the same phase or layer, or in different layers, increases the heat dissipation efficiency and heat absorption efficiency at the upper and lower limits of the third specific temperature range, and allows the temperature of the workpiece to be controlled within the third specific temperature range. Furthermore, by combining multiple types of inorganic particles, particularly nanoparticles, it is possible to more efficiently capture the radiation spectrum of a heat source such as sunlight, and further increase the heat absorption efficiency.

[0097] Here, the average particle size of the inorganic particles, for example, the first inorganic particles and the second inorganic particles, is preferably in the range of 1 nm to 100 μm, particularly in the range of 5 nm to 100 nm, as in Coating-1 and Coating-2. Furthermore, at least one of the first inorganic particles and the second inorganic particles is preferably an inorganic particle having a reflectance of 60% or less, for example, 1 to 40%, particularly 5 to 20%, in the wavelength range of 780 to 25,000 nm. Furthermore, from the viewpoint of increasing the reflectance of Coating-3, the other inorganic particle may have a reflectance of, for example, about 40 to 80%, particularly about 50 to 70%.

[0098] <Preparation of Coating> Coating-1 of this embodiment can also be prepared by the same method as Coating-1 and Coating-2, for example, using the inorganic particles and binder described above. Coating-3 is also preferably a coating obtained by applying and drying ink or paint, but the composition other than the inorganic particles, such as the type of solvent or additive, and the amount of each component, may be the same as the composition of Coating-1 and / or Coating-2. The method of application to the substrate and the thickness of the coating, particularly the coating or film, may also be the same as in the case of Coating-1.

[0099] The upper limit temperature of the third specific temperature range is preferably set, as with Coating-1, within a range of, for example, −30° C. or higher and lower than 200° C., particularly within a range of 20 to 100° C., and particularly within a range of 40 to 80° C. The lower limit temperature of the third specific temperature range is preferably set, as with Coating-2, within a range of, for example, −60° C. or higher and lower than 40° C., and particularly within a range of −10 to 20° C. Setting the third specific temperature range within this range makes it possible to maintain a temperature inside a building or vehicle that is comfortable for occupants and passengers, and also makes it possible to further reduce the power and costs for heating and cooling.

[0100] Furthermore, taking into consideration the temperatures of the furnace, engine, etc., the upper limit temperature of the third specific temperature range can be set to, for example, 200° C. or higher and 1000° C. or lower, and the lower limit temperature of the third specific temperature range can be set to, for example, 40° C. or higher and 200° C. More specifically, Coating-3 of this embodiment includes, for example, the coatings described in (IX) to (XII) below.

[0101] (IX) A coating formed on a building or construction material, containing at least one type of inorganic particle; characterized in that the coating has a light absorptance of 30% or more at the maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and when a radiation peak in the radiation spectrum of the concrete or stone material constituting the building or construction material and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at a temperature of -30°C or higher and lower than 200°C, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more; and when a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the concrete or stone material and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at a temperature of -60°C or higher and lower than 40°C, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more.

[0102] (X) A coating that contains at least one type of inorganic particle and is formed on a vehicle such as an automobile or train; the coating has a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and when a radiation peak in the radiation spectrum of a metal material that constitutes the vehicle and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at a temperature of -30°C or higher and lower than 200°C, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more; and when a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the metal material and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at a temperature of -60°C or higher and lower than 40°C, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more.

[0103] (XI) A coating that contains at least one type of inorganic particle and is formed on a furnace material, engine, or engine-peripheral part; the coating has an optical absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and when a radiation peak in the radiation spectrum of a constituent material of the furnace material, engine, or engine-peripheral part and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at a temperature of 200°C or higher and 1,000°C or lower, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or higher; and when a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the constituent material and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at a temperature of 40°C or higher and 200°C or lower, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or higher.

[0104] (XII) A coating comprising at least one type of inorganic particle and formed on a component or housing of an electric or electronic device; characterized in that the coating has a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and when a radiation peak in the radiation spectrum of a component material of the electric or electronic device or housing and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at a temperature of -30°C or higher and lower than 200°C, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more; and when a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the component material and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at a temperature of -60°C or higher and lower than 40°C, the ratio of the overlapping area to the total area of ​​the radiation peaks is 5% or more.

[0105] The present invention also encompasses the use of the above-mentioned Coating-3 on the treated objects constituting buildings, building materials, vehicles, vehicle parts, furnace materials, engines, engine peripheral parts, or parts or housings of electrical or electronic equipment.

[0106] <<Temperature Control Method of Workpiece>> By applying Coating-1, Coating-2, or Coating-3 as described above to the workpiece, for example by forming these coatings on the workpiece, or by laminating a separately formed coating, such as a film, on the workpiece, it becomes possible to control the temperature of the workpiece and its interior. The present invention also provides the following temperature control methods (a) to (d).

[0107] (a) A method for controlling the temperature of a workpiece to a first specific temperature or lower by applying a coating containing at least one type of inorganic particle to the workpiece, the method being characterized by preparing the coating so that it has a light absorptance of 30% or higher at an absorption maximum wavelength in a wavelength range of 780 to 25,000 nm, a heat capacity that is smaller than the heat capacity of the workpiece, and an overlap area of ​​a radiation peak in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating when both are normalized by their maximum values ​​at the first specific temperature is 5% or higher of the total area of ​​the radiation peaks.

[0108] (b) A method for controlling the temperature of a workpiece to a second specific temperature or higher by applying a coating containing at least one type of inorganic particles to the workpiece, characterized in that the coating has a light absorptance of 30% or higher at a maximum absorption wavelength in a wavelength range of 780 to 25,000 nm, and is prepared so that, when both an emission peak in the emission spectrum of a heat source radiating heat rays to the workpiece and an absorption peak in the absorption spectrum of the coating are normalized by their maximum values ​​at the second specific temperature, the overlapping area is 5% or higher of the total area of ​​the emission peaks.

[0109] (c) A method for controlling the temperature of a third specific temperature range by applying a coating containing at least one type of inorganic particles to the object to be treated, and maintaining the temperature of the object at or below the upper limit temperature of the third specific temperature range and at or above the lower limit temperature of the third specific temperature range, characterized by preparing the coating so that it has a light absorptance of 30% or more at a maximum absorption wavelength in a wavelength range of 780 to 25,000 nm, and that, when a radiation peak in the radiation spectrum of the object to be treated and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values ​​at the upper limit temperature of the third specific temperature range, the overlapping area is 5% or more of the total area of ​​the radiation peaks, and that, when a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the object to be treated and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values, the overlapping area is 5% or more of the total area of ​​the radiation peaks, at the lower limit temperature of the third specific temperature range.

[0110] (d) A method for controlling the temperature of a third specific temperature range by applying a coating containing two or more types of inorganic particles to the object to be treated, and maintaining the temperature of the object at or below the upper limit temperature of the third specific temperature range and at or above the lower limit temperature of the third specific temperature range; the coating has a light absorptance of 30% or more at an absorption maximum wavelength in a wavelength range of 780 to 25,000 nm; first inorganic particles and second inorganic particles are selected as the inorganic particles; the first inorganic particles are selected to have a specific heat smaller than that of the object to be treated; the second inorganic particles are selected to have a specific heat larger than that of the object to be treated; and the upper limit temperature of the third specific temperature range is maintained at or above the lower limit temperature of the third specific temperature range. and adjusting the temperature range so that, when a radiation peak in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values, the overlapping area of ​​the radiation peaks in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating is 5% or more of the total area of ​​the radiation peaks at the lower limit temperature of the third specific temperature range; and adjusting the temperature range so that, when a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the workpiece and an absorption peak in the absorption spectrum of the coating are both normalized by their maximum values, the overlapping area of ​​the radiation peaks in the radiation spectrum of the ... is 5% or more of the total area of ​​the radiation peaks.

[0111] <<Composite Laminate - First Embodiment>> The coating and temperature control method of the present invention can be applied to various types of workpieces. That is, the coating of the present invention can be formed on workpieces such as concrete, stone, wood, glass, ceramic, metal, metal-coated objects, metal-deposited objects, or resin. There are no particular limitations on the shape of the workpiece, and the coating can be applied to a variety of articles, such as buildings, vehicles such as automobiles and trains, furnaces such as electric furnaces and incinerators, and housings and substrates for electrical and electronic devices such as home appliances.

[0112] The present invention also encompasses a composite laminate of the first embodiment, which includes a substrate and a coating of the present invention, such as Coatings-1 to -3, laminated directly or indirectly via an intermediate layer on the surface of the substrate. Note that, for the purpose of distinguishing the coating from the translucent coating in the composite laminate of the second embodiment described below, Coatings-1 to -3 may be referred to below as the "first coating," and the translucent coating in the second embodiment as the "second coating." Furthermore, intermediate layers that may be included in the composite laminate include, but are not limited to, layers of adhesives, sealing materials, rust inhibitors, anti-reflective agents, heat insulating materials, heat-shielding materials, etc. Such composite laminates can be assembled into buildings, vehicles, various industrial products, home appliances, etc., as building materials such as roof tiles and wall materials, vehicle parts, furnaces, and housings and parts for electrical and electronic devices.

[0113] The coating film of the present invention and the coating film in the composite laminate preferably have a transmittance of 60% or more, more preferably 70% or more, and even more preferably 80% or more. When the coating film of the present invention is applied to buildings or vehicles, such a high transmittance offers the advantage of preventing deterioration of the appearance. Furthermore, the maximum value of reflectance in the wavelength range of 780 to 25,000 nm is preferably 40% to 70%, even more preferably 45% to 65%, and even more preferably 50% to 60%. A coating film with such a reflectance makes it easy to suppress excessive temperature rise of the treated object.

[0114] The present invention further includes the use of the coatings of the present invention, such as the above Coatings-1 to 3, for temperature control of buildings, building materials, vehicles, vehicle parts, furnace materials, engines, engine-related parts, or parts or housings of electrical or electronic equipment. The present invention still further includes the use of the above composite laminates in treated objects constituting buildings, building materials, vehicles, vehicle parts, furnace materials, engines, engine-related parts, or electrical or electronic equipment.

[0115] Here, if the substrate is a plate material and the coating is a coating, such as a film, formed on the surface of the plate material, assembly into various products becomes easy. Buildings, vehicles, electrical equipment, and electronic devices made of such composite laminates have the advantage that their interiors can be maintained at an appropriate temperature. Furthermore, when starting up a furnace or engine in winter, it is possible to reduce the initial power input and the energy required for warm-up operation.

[0116] The object to be treated may also be a substrate for an electric or electronic device. The substrate on which the coating of the present invention is formed has good heat dissipation efficiency, so that the components are less likely to be exposed to high temperatures even when used for a long period of time, which is advantageous in that malfunctions and breakdowns are less likely to occur.

[0117] <<Composite Laminate - Second Embodiment>> As a second embodiment, the present invention also encompasses a composite laminate including: a substrate having a colored surface with a light absorptance of 30% or more at a maximum absorption wavelength in a wavelength range of 780 to 25,000 nm; and a light-transmitting coating film (second coating) made of a light-transmitting material and covering the colored surface of the substrate, wherein the composite laminate has a light reflectance of 30% or more at a maximum reflection wavelength in a wavelength range of 780 to 25,000 nm when light is irradiated from the surface side of the light-transmitting coating film toward the composite laminate.

[0118] <Substrate> In this embodiment, the term "substrate having a colored surface" refers to a molded product such as metal, glass, or concrete having a colored surface. Typical examples include, but are not limited to, coated metals used in the bodies of automobiles and trains, the exterior walls of buildings, and colored housings for electronic and electrical devices. The substrate encompasses all molded products made of various known materials, such as metals, coated metals, glass, resin, wood, concrete, stone, and ceramics.

[0119] (Colored Surface) In this embodiment, the colored surface exhibits a light absorptance of 30% or more at the maximum absorption wavelength in the wavelength range of 780 to 25,000 nm. When a substrate has a colored surface with such a light absorptance, after being coated with a light-transmitting coating film described below, the light-transmitting coating film exerts a significant effect of suppressing temperature rise. In particular, the effect of suppressing temperature rise by the light-transmitting coating film is particularly significant for substrates having a colored surface with a light absorptance of 50% or more, especially 70% or more.

[0120] The colored surface is not particularly limited in hue, pattern, uneven shape, etc., as long as the light absorptance of the entire substrate surface is 30% or more at the maximum of the absorption spectrum. However, since the temperature rise suppression effect generally tends to be more pronounced as the light absorptance of the colored surface increases, the hue of the colored surface is preferably a dark color with a total solar radiation of, for example, 40% or less, particularly 30% or less, and especially 20% or less, typically black, or dark gray, navy blue, dark blue, dark green, brown, crimson, brown, burnt brown, adzuki bean color, etc. The colored surface may also be orange, pink, etc., or may have an appearance consisting of multiple hues.

[0121] (Light Absorbance) The light absorbance of the colored surface can be measured using a general-purpose ultraviolet-visible-infrared spectrophotometer, an infrared spectrometer, an infrared camera, etc. For example, the light absorbance in the wavelength range of 780 to 25,000 nm may be read from the measured infrared absorption spectrum, and the maximum value of the spectrum at the measured wavelength and over the entire surface of the substrate may be used.

[0122] <Light-Transmitting Coating Film> In the composite laminate of the second embodiment, the colored surface of the substrate is coated with a light-transmitting coating film made of a light-transmitting material, and when the composite laminate is irradiated with light from the surface side of the light-transmitting coating film, the light reflectance at the maximum reflection wavelength in the wavelength range of 780 to 25,000 nm is 30% or more. In particular, the light reflectance in this wavelength range is preferably 35% or more, more preferably 40% or more, and even more preferably 99% or less, or even more preferably 70% or less, for example 40 to 99%.

[0123] In the composite laminate of the second embodiment, the light-transmitting coating film has a visible light transmittance of, for example, 20% or more, preferably 30% or more, more preferably 40% or more, even more preferably 60% or more, and ideally 70% or more. Providing such a high light transmittance has the advantage of making it easier to maintain the appearance of the substrate.

[0124] (Material of the Light-Transmitting Coating Film) A composite laminate having a light reflectance of 30% or more at a reflection maximum wavelength in the wavelength range of 780 to 25,000 nm can be obtained, for example, by using a light-transmitting coating film containing one or more inorganic particles selected from the group consisting of doped semiconductors (doped semiconductors), degenerate semiconductors, semimetals, and Mxene. When applied to a general substrate such as a glass or quartz substrate, a light-transmitting coating film containing these inorganic particles generally has a light reflectance of 30% or more, particularly 40% to 99%, and especially 50% to 70%, in the above wavelength range. Therefore, after coating the colored surface of the base material, it is easy to obtain a light-transmitting composite laminate having a maximum light reflectance of 30% or more on the coating film surface.

[0125] Here, examples of doped semiconductors, degenerate semiconductors (heavily doped semiconductors), semimetals, and Mxene include, but are not limited to, inorganic particles such as those used in the above-mentioned Coatings 1 to 3. In particular, doped semiconductors and / or heavily doped semiconductors are preferred.

[0126] Specific examples of doped and heavily doped semiconductors include tin-doped indium oxide (ITO), aluminum-doped indium oxide, cerium-doped indium oxide, antimony-doped indium oxide (ATO), aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide, indium-doped cadmium oxide, fluorine-doped indium oxide, fluorine-doped cadmium oxide, chlorine-doped cadmium oxide, bromine-doped cadmium oxide, cesium-doped molybdenum oxide, antimony-doped tin oxide, fluorine-doped tin oxide, titanium oxide, copper sulfide, copper phosphide, copper telluride, copper selenide, ruthenium oxide, rhenium oxide, molybdenum oxide, tungsten oxide, tungsten bronze, nickel sulfide, and CuWS. ４ , tungsten-doped TiO ２ , molybdenum-doped TiO ２ , Bi ２ WO ６ These include, but are not limited to:

[0127] There are no particular limitations on the particle size of the inorganic particles, and inorganic particles with any average particle size and particle size distribution can be used. Preferably, nanoparticles such as those used in Coatings 1 to 3 are used, specifically inorganic particles with an average particle size in the range of 1 nm to 100 μm, particularly 5 nm to 100 nm. Such nanoparticles are less likely to scatter light with wavelengths of, for example, about 350 to 1000 nm, making it easy to increase the maximum reflectance without significantly impairing the light transmittance of the coating.

[0128] The light-transmitting coating film may also contain various polymers as a binder for inorganic particles or as a light-transmitting coating film material itself that exhibits a light reflectance of 30% or more on a substrate. Small molecules with multiple coordination sites, such as ethanedithiol, succinic acid, and ethylenediamine, or photopolymerizable compounds, or diamond-like carbon, can also be used as binders. Specific examples of binders include, but are not limited to, the polymers used in Coatings 1 to 3 described above. Condensates of alkoxysilanes, silanols, and the like can also be used as binders.

[0129] (Coating Thickness) There are no particular limitations on the thickness of the light-transmitting coating film in the composite laminate of the second embodiment. Depending on the substrate to be coated, the material of the light-transmitting coating film, and the intended use, the thickness can be, for example, 10 nm to 1 mm, or optionally 100 nm to 100 μm, and particularly about 1 to 50 μm. A light-transmitting coating film of this thickness can easily achieve a light reflectance of, for example, 30% on the surface side of the light-transmitting coating film of the composite laminate without significantly impairing the light transmittance.

[0130] <Light Reflectance and Transmittance> The light reflectance and transmittance can be measured by the methods specified in, for example, JIS K 7375, JIS K 7361-1, etc. In this embodiment, the total light transmittance and total light reflectance of light in the wavelength range of 780 to 25,000 nm are measured using an apparatus such as an integrating sphere light transmittance measuring apparatus in accordance with the JIS K 7375 method, and the values ​​thus measured are used.

[0131] Although the present invention is not limited by any particular theory, one reason why the composite laminate of the second embodiment can suppress temperature rise in the substrate is that the formation of the translucent coating film increases the reflection of irradiated light, thereby suppressing the light energy absorbed by the entire composite laminate, including the substrate. Light reflection primarily occurs at interfaces, such as the interface between air and the translucent coating film (the surface of the translucent coating film) or the interface between the translucent coating film and the colored surface. However, it is believed that light scattering within the translucent coating film, reflection from the colored surface itself, and even light scattering within the substrate also have an effect. Other possible factors include differences in the spectral overlap of the irradiated light between the colored surface of the substrate and the translucent coating film, and differences in the number of absorbed photons.

[0132] <One Aspect of the Composite Laminate of the Second Embodiment> The composite laminate of this embodiment includes an aspect in which, when light is irradiated from the surface side of the translucent coating film toward the composite laminate, in other words, when light is irradiated from the surface of the translucent coating film toward the composite laminate, the light reflectance at the reflection maximum wavelength is greater than the light absorptance of the colored surface at the absorption maximum wavelength. If the light reflectance after formation of the translucent coating film is greater than the light absorptance of the colored surface of the substrate before coating film formation, the light energy actually reflected on the surface side of the translucent coating film is greater than the light energy absorbed when the colored surface of the substrate is exposed, making it easier to suppress temperature rise. Note that the translucent coating film in this aspect can be produced using, for example, inorganic particles or polymers such as those described above.

[0133] Another aspect of the composite laminate of the second embodiment The composite laminate of this embodiment also includes an aspect in which the number of absorbed photons in the wavelength range of 780 to 25,000 nm when light is irradiated from the surface side of the light-transmitting coating film toward the composite laminate, in other words, when light is irradiated from the surface of the light-transmitting coating film toward the composite laminate, is smaller than the number of absorbed photons in that wavelength range on the colored surface. If the number of absorbed photons after the light-transmitting coating film is formed is smaller than the number of absorbed photons on the colored surface of the substrate before the coating film is formed, the photon absorption on the surface side of the light-transmitting coating film is smaller than the photon absorption when the colored surface of the substrate is exposed, and therefore it is easier to suppress the temperature rise of the entire composite laminate including the substrate. The light-transmitting coating film in this aspect can also be produced using, for example, inorganic particles or polymers such as those described above.

[0134] The composite laminate of this embodiment further includes an embodiment in which, when light is irradiated from the surface side of the light-transmitting coating film toward the composite laminate, in other words, when light is irradiated from the surface of the light-transmitting coating film toward the composite laminate, the number of reflected photons in the wavelength range of 780 to 25,000 nm is greater than the number of reflected photons in the same wavelength range from the colored surface. In such an embodiment, the reflectance is increased by the coating of the light-transmitting coating film, thereby suppressing absorption of light energy and further facilitating suppression of temperature rise. The light-transmitting coating film of this embodiment can also be produced using, for example, the inorganic particles and polymers described above.

[0135] (Number of absorbed photons, number of reflected photons) Here, the number of absorbed photons is the number of photons of irradiated light that are absorbed by a substance, and the number of reflected photons is the number of photons of irradiated light that are reflected by a substance. For example, these can be measured using a UV-3600i Plus (with an integrating sphere) manufactured by Shimadzu Corporation.

[0136] The degree of temperature rise due to photon absorption by the light-transmitting coating film can also be affected by the photothermal conversion coefficient of the light-transmitting coating film. In the composite laminate of this embodiment, it is more preferable that the integral of the product of the number of absorbed photons and the photothermal conversion coefficient of the light-transmitting coating film at each wavelength in the wavelength range of 780 to 25,000 nm is smaller than the integral of the product of the number of absorbed photons and the photothermal conversion coefficient of the colored surface of the substrate at each wavelength.

[0137] <Another Aspect of the Composite Laminate of the Second Embodiment> The composite laminate of this embodiment further includes an aspect in which the light reflectance at the maximum reflection wavelength when light is irradiated from the surface side of the light-transmitting coating film toward the composite laminate, in other words, when light is irradiated from the surface of the light-transmitting coating film toward the composite laminate, is greater than the light reflectance of the colored surface at the maximum reflection wavelength in the wavelength range of 780 to 25,000 nm. In this aspect, the light energy reflected on the surface side by the light-transmitting coating film is increased, thereby further facilitating heat dissipation. The light-transmitting coating film of this aspect can also be produced using, for example, the inorganic particles and polymers described above.

[0138] <<Method for producing the composite laminate of the second embodiment>> The composite laminate of this embodiment can be produced by coating the above-mentioned substrate with the above-mentioned light-transmitting coating film. There are no particular limitations on the coating method, and various conventional techniques can be used. For example, a film-like light-transmitting coating film may be formed and adhered or fused to the surface of the substrate, or the composite laminate can be produced by preparing a paint as a light-transmitting coating film precursor, applying it to the surface of the substrate, and drying it. Depending on the material of the substrate, the composite laminate of the second embodiment can also be produced by a method such as applying inorganic particles to the surface and heating to fuse them. Adhesion using an adhesive is also possible. Of these, the method of applying a paint is preferred because it can be easily performed with a simple operation regardless of the shape of the substrate.

[0139] <Preparation of Paint> The paint as a coating precursor can be prepared, for example, by mixing the inorganic particles described above with a binder such as a polymer or a carbon material. There are no particular limitations on the mixing ratio between the two, and a desired ratio can be set depending on the type of substrate to be applied, the usage environment, etc. For example, the mass ratio of inorganic particles:binder may be 0.001 to 99:99.999 to 1, particularly 0.05 to 30:99.95 to 70, but is not limited thereto.

[0140] The mixing method is not particularly limited, and for example, various polymers such as polyester, urethane, epoxy, polyvinyl alcohol, polyvinyl butyral, and silicone can be mixed with inorganic particles in a solvent and applied to the substrate as an ink or paint. Here, it is also possible to use a monomer such as alkoxysilane or silanol instead of the polymer, and condense these into a binder after mixing with the inorganic particles or after mixing and applying them to the substrate.

[0141] There are no particular limitations on the solvent used in the paint, and any solvent may be used as long as it can dissolve the polymer, monomer, etc. used. For example, the same solvents as those used in the inks and paints for forming the above-mentioned Coatings-1 to -3, such as hydrocarbons, can be used, but are not limited to these. In addition, ordinary additives to paints, such as dispersants, surfactants, stabilizers, antioxidants, pH adjusters, viscosity adjusters, etc., can also be used. There are also no particular limitations on the mixing ratio of such solvents with inorganic particles, binders, and additives, and they can be, for example, the same mass ratio as that of the inks and paints for forming the Coatings-1 to -3.

[0142] In addition, in forming the translucent coating film in this second embodiment, depending on the type of inorganic particles and substrate, a paint in which inorganic particles are dispersed in a solvent can be used without using a binder. Depending on the type and amount of binder or additive, the translucency of the translucent coating film may be reduced, but a paint in which inorganic particles are dispersed in a solvent can eliminate this concern. For example, a paint in which ITO is dispersed in toluene can also be used. The concentration of the inorganic particles is not particularly limited, and can be, for example, 0.001 to 99% by mass, more preferably 0.1 to 20% by mass, and particularly 1 to 10% by mass, depending on the coating properties, etc.

[0143] <Formation of Light-Transmitting Coating Film> A coating film (light-transmitting coating film) can be formed on the surface of a substrate by applying the above-mentioned coating material to the surface of the substrate and evaporating the solvent to dryness. It is also possible to use a photopolymerizable compound as a binder and form a coating film (light-transmitting coating film) by photopolymerization. It is also possible to use a thermally polymerizable compound as a binder and form a coating film (light-transmitting coating film) by thermal polymerization. It is also possible to use a compound that polymerizes with an electron beam as a binder and form a coating film (light-transmitting coating film) by polymerization with an electron beam.

[0144] <Substrates on which a translucent coating film is formed> As described above, examples of substrates on which a translucent coating film is formed include, but are not limited to, metal-coated objects used in automobile and train bodies, exterior walls of buildings, and colored housings of electronic and electrical equipment. The substrate material may be any known material, such as metal, metal-coated objects, glass, resin, wood, concrete, stone, ceramic, or metal deposition thereon. In particular, composite laminates using metal-coated objects, particularly dark-colored metal-coated objects such as black and navy blue, as the substrate are likely to exhibit a temperature rise suppression effect and are useful for applications such as automobile bodies. In addition, a translucent coating film may be formed using, as the substrate, building materials made of concrete, stone, glass, ceramic, or a composite thereof, such as roof tiles.

[0145] The light-transmitting coating film can be formed into two or more layers. The light-transmitting coating film can also be patterned or coated in the shape of a design, picture, or the like. Furthermore, a polymer film, such as a resin film, can be used as a substrate, and the composite laminate can be formed into a film or sheet shape and applied to vehicles or building materials.

[0146] A specific example of the composite laminate of this embodiment is an automobile body part comprising: a substrate made of a coated metal or resin having a colored surface with a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and a light-transmitting coating film made of a light-transmitting material that coats the colored surface of the substrate; characterized in that when light is irradiated from the surface side of the light-transmitting coating film toward the main body of the automobile body part, the light reflectance at a maximum reflection wavelength in the wavelength range of 780 to 25,000 nm is 30% or more. In an automobile equipped with such a body part, for example, a body panel, the rise in interior temperature can be suppressed, thereby reducing the risk of heatstroke, especially in the summer.

[0147] The substrate on which the light-transmitting coating film is formed may also be the composite laminate of the first embodiment, including the above-described Coatings-1 to -3 (first coating). That is, the present invention also encompasses a composite laminate of the first embodiment, further including a light-transmitting coating film as a second coating; the coating (first coating) has a colored surface with a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; the light-transmitting coating film (second coating) is made of a light-transmitting material and covers the colored surface of the coating (first coating); and when light is irradiated toward the composite laminate from the surface side of the light-transmitting coating film (second coating), the light reflectance at a maximum reflection wavelength in the wavelength range of 780 to 25,000 nm is 30% or more. Such a composite laminate can improve the heat dissipation efficiency and / or heat absorption efficiency of the workpiece, particularly the former, and further suppress temperature rise of the coated substrate.

[0148] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these descriptions in any way.

[0149] Example 1: A coating of ITO powder (Sn doping amount: 0.5% by mass, emissivity: approximately 20%) as inorganic particles was applied to one side of a 150 mm thick concrete plate (substrate, emissivity: 90%) and dried to form a 0.365 μm thick coating (film). An environmental simulation was performed using a composite laminate. Because the coating was extremely thin compared to the concrete plate, the heat capacity of the coating was smaller than that of the concrete plate being treated. In the environmental simulation, a two-tiered box-like structure (width: 4700 mm, depth: 4700 mm, middle plate (partition plate) height: 2775 mm, total height: 6000 mm) was used as a model, assembled using the composite laminate and an uncoated concrete plate, as shown in the cross-sectional perspective view of FIG. 2 . The two-tiered box was constructed using a composite laminate for the top panel and left and right side panels, and uncoated concrete panels for the middle panel, bottom panel, front panel (not shown) and back panel, and the test was carried out under the assumption that the top panel and left and right side panels were assembled so that the paint film was on the inner surface of the two-tiered box-like object.

[0150] Next, the top plate of the two-tiered box-shaped object was heated until its top surface reached 60°C, and then the heating was stopped and the two-tiered box-shaped object was left in an atmosphere at room temperature (25°C). Temperature changes after 6 hours were simulated at the following measurement points: the outer surface of the top plate (point A in Figure 1), the inner surface of the top plate (point B in Figure 1), the center of the upper space separated by the middle plate in the internal space of the two-tiered box-shaped object (point C in Figure 1), the top surface of the middle plate (point D in Figure 1), and the center of the lower space separated by the middle plate in the internal space of the two-tiered box-shaped object (point E in Figure 1). The results of these simulations are shown in Table 1 and Figures 3 and 4.

[0151] Comparative Example 1 Simulations were performed in the same manner as in Example 1, except that all of the plates constituting the two-tiered box-shaped structure were uncoated concrete plates instead of composite laminates. The results of these simulations are shown in Table 1 and Figures 3 and 4.

[0152] Examples 2 to 6 and Comparative Example 2 Simulations were carried out in the same manner as in Example 1, except that the inorganic particles contained in the coating film (film) were changed to those shown in Table 1. The results are shown in Table 1 and Figures 3 and 4, together with the emissivity of the inorganic particles in the coating film and the ratio (overlap ratio) of the overlap area α of the radiation peak and the absorption peak to the area β of the entire radiation peak.

[0153]

[0154] As shown in Table 1 and Figures 3 and 4, the two-tiered box-shaped object provided with a coating containing specific inorganic particles according to the present invention had a temperature drop of 0.7 to 3.7°C after six hours at all measurement points, and in most cases, a drop of more than 1°C, compared to Comparative Example 1, which had no coating. Among Examples 1 to 6, the greatest temperature-reducing effect was observed in Example 1, which used a coating containing ITO with a 0.5% Sn doping amount. Furthermore, Comparative Example 2, which used inorganic particles with an overlap ratio of less than 5%, did not achieve a sufficient temperature-reducing effect. It became clear that the temperature-reducing effect is affected by the emissivity of the inorganic particles and the spectral overlap area, and that it is important to use inorganic particles with an overlap ratio of 5% or more.

[0155] The reason why the internal temperature was lower with the coating than without the coating is thought to be that the coating promoted heat dissipation from the concrete slab, allowing the concrete to rapidly release heat, lowering the temperature of the concrete itself and reducing the effect of the heat dissipation from the concrete to the inside. For example, as shown in Figure 3, at point B on the surface where the coating was formed, the temperature temporarily rose immediately after heating was stopped due to heat transferred from the top surface of the top plate (point A). However, with the coating of the present invention, the heat was dissipated more quickly, resulting in a smaller temporary temperature rise and a larger subsequent temperature drop. Furthermore, at points D and other locations, the coating of the present invention simultaneously promoted heat dissipation from the top plate, suppressing the temperature rise. Furthermore, in the examples of the present invention, as a result of this reduction in the temperature of the entire concrete slab, the temperatures at measurement points C and E, etc., six hours after heating was stopped were also lower than those without the coating.

[0156] Examples 7-8 and Comparative Example 3: Experiments to verify the results of the simulation were conducted using concrete coated with ITO particles. Cement and water were mixed and solidified in an ice-making container to create a 10 mm square concrete block sample. ITO nanoparticles (Sn doped at 0.5% or 2%) were coated on six sides of the resulting sample using hydrazine (thickness: 0.365 μm).

[0157] The samples after coating (Examples 7 and 8) and a concrete block sample without a coating (Comparative Example 3) were placed on a heater at 115°C. When the upper surface temperature of the sample of Comparative Example 3 reached approximately 60°C, heating was stopped, and the upper surface temperature of each sample was measured when the temperature had almost stabilized. The results are shown in Table 2.

[0158]

[0159] It has been found that concrete blocks coated with a coating containing suitable inorganic particles according to the present invention can efficiently dissipate heat and exhibit a large temperature drop.

[0160] Example 9 The degree of temperature drop (temperature drop) when various coating films were formed on a black substrate having a radiation spectrum (vertical axis: intensity; right axis) as shown by the thick dashed line in Figure 5 was simulated. The simulation was performed assuming that the coating film had a spectrum showing a linear peak at a single point within a wavelength range of 3,000 to 30,000 nm (0.003 to 0.03 mm). The temperature drop of the sample with each coating film formed compared to the sample without the coating film was simulated and plotted against the wavelength of the absorption peak of each coating film (black circles in Figure 5).

[0161] As shown in Figure 5, the results showed that the temperature drop tends to be greater when the absorption peak position (wavelength) of the coating film is close to the peak position of the radiation spectrum of the treated object. In particular, it was found that the temperature drop effect is remarkable for coatings that show an absorption peak about 100 to 5000 nm from the peak wavelength of the radiation spectrum, especially about 1000 to 3000 nm on the short wavelength side (high energy side).

[0162] Example 10 and Comparative Example 4 A demonstration experiment to verify the results of the simulation was carried out using a glass plate coated with a heat-shielding material and ITO particles. A film of CuS nanoparticles (film thickness 0.365 μm) was formed as a heat-shielding material on a glass plate with a thickness of 1 mm and an area of ​​25 × 25 mm. Then, a film of ITO nanoparticles (Sn doping amount 2%) was laminated on the film (film thickness 0.365 μm) to obtain a composite glass plate (composite laminate). Ethylenediamine was used as a binder.

[0163] A sample after film formation (Example 10) and a glass sample without an ITO coating (coated only with a heat-shielding material) (Comparative Example 4) were irradiated with AM1.5 light, and the temperature of each sample after it reached a constant temperature was measured using a thermograph. Note that AM1.5 is the average solar spectrum on the ground at latitudes near Japan. The number after AM indicates the amount of atmosphere through which sunlight passes before reaching the earth's surface, i.e., air mass. AM0 is the solar spectrum outside the atmosphere, where sunlight does not pass through the atmosphere, and AM1 is the spectrum when sunlight is incident perpendicularly to the earth's surface directly on the equator. Japan is located roughly between 24 and 45° north latitude, where the amount of atmosphere through which sunlight passes is approximately 1.5 times that of sunlight directly on the equator. Therefore, AM1.5 at an incidence angle of 41.8° to the earth's surface is often used as the standard solar spectrum on the earth's surface. The results are shown in Table 3.

[0164]

[0165] The above examples demonstrate that a treated object coated with a coating according to the present invention can efficiently dissipate heat and control the temperature of the treated object and its interior. In fields such as construction, a difference of 1°C can have a significant impact on the power and costs required for air conditioning and heating. Furthermore, thermal cracking is a constant problem in glass windows, and no effective solution has yet been found. Reducing the temperature of a glass sheet by 1°C under sunlight exposure is also valuable in terms of producing glass that is less susceptible to thermal cracking.

[0166] Example 11 and Comparative Example 5 ITO nanoparticles (Sn doping amount 7%, average particle diameter 15 nm) were mixed with toluene to a concentration of 5 wt % to prepare a coating material. The prepared coating material was applied (applied) using a spin coater to the coated surface of a tin plate (test piece, manufactured by Nippon Test Panel Co., Ltd.) whose one surface had been painted black, and the coating material was allowed to dry naturally to form an ITO coating (coating thickness 20 μm).

[0167] The surface temperature, reflectance, and other parameters were measured for the samples coated with the resulting translucent surface coating material and for the samples without the surface coating material. A test piece (TP1) with the ITO coating on the black coated surface and a test piece (TP0) without the ITO coating on the black coated surface were exposed to a Xe lamp for 15 minutes, with the black coated surface facing up. After reaching a steady state, the difference in surface temperature between the two (based on the surface temperature of the exposed surface of the uncoated TP0) was determined (Example 11). The reflectance of the ITO-coated surface was maximized between 1900 and 2100 nm. For comparison, the same procedure was performed on a silver tin plate without a colored coating (Comparative Example 5). The results are shown in Table 4, along with the reflectance at 2000 nm and the light absorptance of the uncoated surface.

[0168]

[0169] As shown in Example 11, the surface of the composite laminate (TP1) on which the light-transmitting coating film according to the present invention was applied had a higher surface reflectance, i.e., a lower light absorption coefficient, compared to the colored surface of the substrate (the surface on which the ITO coating film was not formed), and as a result, the substrate was able to be maintained at a lower temperature. However, as shown in Comparative Example 5, it was revealed that this effect was not achieved when the reflectance of the substrate surface was higher than the reflectance of the composite laminate surface.

[0170] 1 Absorption spectrum of coating 2 Radiation spectrum of treated object 3 Radiation spectrum of heat source α Overlap area of ​​absorption peak in absorption spectrum and radiation peak in radiation spectrum β Total area of ​​radiation peaks γ Overlap area of ​​absorption peak in absorption spectrum and radiation peak in radiation spectrum δ Total area of ​​radiation peaks 10 Hypothetical two-tiered box-shaped object in Examples 1 to 6 A to E Temperature measurement points

Claims

1. A coating that contains at least one type of inorganic particle and is formed on a workpiece, the coating having a light absorptance of 30% or more at a maximum absorption wavelength in a wavelength range of 780 to 25,000 nm, the coating having a smaller heat capacity than the workpiece, and the coating having a ratio of an overlapping area of ​​a radiation peak in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating, when both are normalized by their maximum values ​​at a first specific temperature, to an area of ​​the entire radiation peak, of 5% or more.

2. A coating containing at least one type of inorganic particle and formed on a workpiece, the coating having a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm, and characterized in that the ratio of an overlapping area of ​​an emission peak in the emission spectrum of a heat source radiating heat rays to the workpiece and an absorption peak in the absorption spectrum of the coating when both are normalized by their maximum values ​​at a second specific temperature to the total area of ​​the emission peaks is 5% or more.

3. A coating containing at least one type of inorganic particle and formed on a workpiece, the coating having a light absorptance of 30% or more at a maximum absorption wavelength in a wavelength range of 780 to 25,000 nm, the ratio of an overlapping area of ​​a radiation peak in the radiation spectrum of the workpiece and an absorption peak in the absorption spectrum of the coating, when both are normalized by their maximum values ​​at the upper limit temperature of a third specific temperature range, to an entire area of ​​the radiation peaks, being 5% or more, and the ratio of an overlapping area of ​​a radiation peak in the radiation spectrum of a heat source that radiates heat rays to the workpiece and an absorption peak in the absorption spectrum of the coating, when both are normalized by their maximum values ​​at the lower limit temperature of a third specific temperature range, to an entire area of ​​the radiation peaks, being 5% or more.

4. A coating according to any one of claims 1 to 3, having a light reflectance of 40% or more and 70% or less at a maximum reflection wavelength in the wavelength range of 780 to 25,000 nm.

5. The coating according to any one of claims 1 to 3, wherein the inorganic particles have an average particle size within the range of 1 nm to 100 μm.

6. The coating of any one of claims 1 to 3, wherein the inorganic particles comprise one or more particles selected from the group consisting of degenerate semiconductors, semimetals, and Mxene.

7. The coating of claim 1, wherein the first particular temperature is within the range of -30°C or more and less than 200°C.

8. The coating of claim 1, wherein the first particular temperature is in the range of 200°C or more and 1000°C or less.

9. The coating of claim 2, wherein the second specified temperature is within the range of -60°C or more and less than 40°C.

10. The coating of claim 2, wherein the second specified temperature is within the range of 40°C or more and 200°C or less.

11. The coating according to claim 3, wherein the third specific temperature range has an upper limit temperature in the range of -30°C or more and less than 200°C, and a lower limit temperature in the range of -60°C or more and less than 40°C.

12. The coating according to claim 3, wherein the third specific temperature range has an upper limit temperature in the range of 200°C or more and 1000°C or less, and a lower limit temperature in the range of 40°C or more and 200°C or less.

13. The coating according to any one of claims 1 to 3, wherein the object to be treated is concrete, stone, wood, glass, ceramics, metal, metal-coated objects, metal-vapor-deposited objects, or resin.

14. An ink or paint containing the inorganic particles and a binder, which is used to form a coating film according to any one of claims 1 to 3.

15. A composite laminate comprising the workpiece and the coating according to any one of claims 1 to 3 laminated directly or indirectly via an intermediate layer on the surface of the workpiece.

16. A composite laminate comprising: a substrate having a colored surface with a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm; and a light-transmitting coating film made of a light-transmitting material and coating the colored surface of the substrate, wherein the composite laminate has a light reflectance of 30% or more at a maximum reflection wavelength in the wavelength range of 780 to 25,000 nm when light is irradiated from the surface side of the light-transmitting coating film toward the composite laminate.

17. The composite laminate according to claim 16, wherein the light reflectance at the maximum reflection wavelength when light is irradiated from the surface side of the light-transmitting coating film toward the composite laminate is 40% or more and 99% or less.

18. A composite laminate according to claim 16 or 17, wherein when light is irradiated from the surface of said light-transmitting coating film towards said composite laminate, the light reflectance at said maximum reflection wavelength is greater than the light absorptance at said maximum absorption wavelength of said colored surface.

19. A composite laminate according to claim 16 or 17, wherein, when light is irradiated towards said composite laminate from the surface of said light-transmitting coating film, the number of absorbed photons in a wavelength range of 780 to 25,000 nm is smaller than the number of absorbed photons in said wavelength range by said colored surface.

20. A composite laminate according to claim 16 or 17, in which, when light is irradiated towards the composite laminate from the surface of the light-transmitting coating film, the number of reflected photons in a wavelength range of 780 to 25,000 nm is greater than the number of reflected photons in the same wavelength range from the colored surface.

21. A composite laminate according to claim 16 or 17, wherein when light is irradiated from the surface of the light-transmitting coating film towards said composite laminate, the light reflectance at said maximum reflection wavelength is greater than the light reflectance at said maximum reflection wavelength in the wavelength range of 780 to 25,000 nm of said colored surface.

22. The composite laminate according to claim 16 or 17, wherein the substrate is made of metal, a metal coating, a metal deposition, glass, resin, wood, concrete, stone, or ceramic.

23. The composite laminate of claim 16 or 17, wherein the light-transmitting coating comprises one or more inorganic particles selected from the group consisting of doped semiconductors, degenerate semiconductors, semimetals, and Mxene.

24. A composite laminate according to claim 15, further comprising a light-transmitting coating film, wherein the coating film has a colored surface having a light absorptance of 30% or more at a maximum absorption wavelength in the wavelength range of 780 to 25,000 nm, the light-transmitting coating film is made of a light-transmitting material and covers the colored surface of the coating film, and when light is irradiated from the surface side of the light-transmitting coating film towards the composite laminate, the light reflectance at a maximum reflection wavelength in the wavelength range of 780 to 25,000 nm is 30% or more.

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