Composite cooling apparatus and method of manufacturing the same

Abstract

To provide a composite cooling apparatus which has high infrared emissivity in an atmospheric window while having high reflectance in an infrared region from a visible light region and which hardly exposes a specific color even in a harsh usage environment while properly maintaining a cooling function even in the case of local heating generation, and a method of manufacturing the same.SOLUTION: A light reflection layer B is made of a metal having a thickness of 50-500 nm and containing 50-100 mass% of copper. A base material layer BA formed from a resin material is provided between an infrared radiation layer J and the light reflection layer B. At least one of the infrared radiation layer J and the base material layer BA includes at least one of a white filler F with an arithmetic mean particle size of 2 μm or less and a hole with an arithmetic mean pore diameter of 0.01-2 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a complex cooling device including an infrared emitting layer that emits infrared light from a emitting surface and a light reflecting layer that is located on the infrared emitting layer opposite to the side where the emitting surface is present, and a manufacturing method thereof. [Background technology]

[0002] Radiative cooling is known as a function for cooling the reverse side of a material. Radiative cooling is a phenomenon in which a material's temperature drops when it radiates electromagnetic waves such as infrared rays into its surroundings. By utilizing this phenomenon, it is possible to create a hybrid cooling device that cools an object without consuming energy such as electricity.

[0003] A conventional example of a composite cooling device is one configured by laminating an infrared radiation layer that radiates infrared light from a radiation surface and a light reflecting layer that is positioned on the infrared radiation layer opposite to the side where the radiation surface is present (see, for example, Patent Document 1). Patent Document 1 indicates that the light reflecting layer is made of silver, a silver alloy, or the like. On the other hand, Patent Document 2 discloses that an infrared radiation layer that emits infrared light from the radiation surface may be composed of a polymer and a plurality of non-polymer particles mixed into the polymer particles, and may also contain copper as a metal that constitutes the light reflecting layer. Furthermore, Patent Document 3 discloses a reflective film that exhibits high solar reflectance using only a white resin layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-165611 [Patent Document 2] Special Publication No. 2019-515967 [Patent Document 3] Japanese Patent Application Laid-Open No. 2018-169456 Summary of the Invention [Problem to be solved by the invention]

[0005] When silver or a silver alloy is used as a light-reflecting layer as in the technology disclosed in Patent Document 1, the composite cooling device itself becomes relatively expensive, and there is also the problem that, under certain harsh environments, silver particles in the silver alloy may aggregate and take on a specific color.

[0006] Furthermore, when silver or a silver alloy is used as the light-reflecting layer, a method called vapor deposition is generally adopted, but silver or a silver alloy is relatively expensive and requires a high temperature during vapor deposition, making it difficult to make the metal layer thick enough and ensuring sufficient thermal conductivity in the planar direction of the light-reflecting layer. Therefore, when the composite cooling device is locally heated, it is difficult to transfer the local heat in the planar direction, and the cooling performance may not be fully demonstrated.

[0007] Therefore, as in the technology disclosed in Patent Document 2, the use of copper as the light reflective layer is being considered, which has lower metal coagulation than silver, is relatively inexpensive, and can be vapor deposited at a lower vapor deposition temperature than silver. However, copper has a low reflectance in the visible light range, and therefore, when used as a light reflecting layer, it is not possible to fully exhibit cooling performance. Furthermore, copper has the property of having low reflectance, particularly in the visible light range. However, the technology disclosed in Patent Document 2 does not consider any configuration for improving the low reflectance, particularly in the visible light range, when copper is used as the metal reflective layer.

[0008] On the other hand, the reflective film disclosed in Patent Document 3, which exhibits high solar reflectance using only a white resin layer, has difficulty in having sufficient reflectance in the near-infrared region of the solar spectrum, and therefore has a relatively low solar reflectance, making it difficult to achieve sufficient cooling performance.

[0009] The present invention has been made in view of the above-mentioned problems, and its object is to provide a composite cooling device that has high reflectance from the visible light region to the infrared region, has high infrared emissivity at the atmospheric window, maintains good cooling function even when localized heating occurs, and is unlikely to reveal a specific color even in harsh usage environments, and a manufacturing method thereof. [Means for solving the problem]

[0010] The composite cooling device for achieving the above object is as follows: A composite cooling device comprising an infrared emitting layer that emits infrared light from a emitting surface, and a light reflecting layer that is located on the infrared emitting layer on the opposite side to the side where the emitting surface is present, and characterized by the following configuration: the light-reflecting layer has a thickness of 50 nm or more and 500 nm or less and is made of a metal containing 50 mass % or more and 100 mass % or less of copper, a base layer formed of a resin material between the infrared radiation layer and the light reflection layer, At least one of the infrared radiation layer and the base layer contains at least one of a white filler having an arithmetic mean particle size of 2 μm or less and pores having an arithmetic mean pore size of 0.01 μm or more and 2 μm or less.

[0011] According to the above-mentioned characteristic configuration, a metal (copper or copper alloy) containing 50 to 100 mass % copper is used as the light-reflecting layer, which is relatively inexpensive and can keep the temperature during deposition relatively low, so that a sufficiently thick light-reflecting layer of 50 to 500 nm can be formed. This ensures sufficient thermal conductivity in the planar direction of the light-reflecting layer, and when the integrated cooling device is locally heated, the local heat can be effectively transferred in the planar direction, thereby enabling sufficient cooling performance. Furthermore, by using copper or a copper alloy for the light reflecting layer, aggregation of metal particles can be suppressed compared to when silver or a silver alloy is used, and the development of a specific color due to aggregation can be prevented.

[0012] Furthermore, copper alone has high reflectance in the infrared light region but low reflectance in the visible light region, and there is concern that visible light may heat the object to be cooled. However, the inventors have discovered that by including at least one of a white filler having an arithmetic mean particle size of 2 μm or less and pores having an arithmetic mean pore size of 0.01 μm or more and 2 μm or less in at least one of the infrared radiation layer and the base material layer, as in the above-mentioned characteristic configuration, it is possible to maintain a certain level of light reflectance in the visible light region, as shown in the test results described below. Incidentally, according to the above-described characteristic configuration, at least one of the infrared radiation layer and the base material layer is configured to have white filler or voids, so the other can be made only of a resin that can exhibit a radiative cooling function by emitting infrared light. Therefore, a sufficient radiative cooling function can be exhibited without making the other of the infrared radiation layer and the base material layer unnecessarily thick.

[0013] The white filler may be of various shapes, such as spherical or elliptical, but in this specification, the arithmetic mean particle size of the white filler means the average value of the shortest diameter of the white filler. Furthermore, the pores may have various shapes, such as spherical or elliptical, but in this specification, the arithmetic mean pore diameter of the pores means the average value of the shortest inner diameter of the pores.

[0014] As described above, it is possible to realize a composite cooling device that has high reflectance from the visible light region to the infrared region, has high infrared emissivity at the atmospheric window, maintains good cooling function even when localized heating occurs, and is unlikely to reveal a specific color even when used under harsh conditions.

[0015] Further features of the combined cooling device include: The white filler has an average particle size of 0.2 μm or more and 1 μm or less.

[0016] Furthermore, the inventors have confirmed that by making the arithmetic mean particle diameter of the white filler sufficiently small, in the range of 0.2 μm to 1 μm, the infrared radiation layer or base layer containing the white filler therein can have a sufficiently high reflectance, particularly for visible light.

[0017] Further features of the combined cooling device include: The resin material forming the base layer includes at least one of a polyester resin, an acrylic resin, and a urethane resin.

[0018] In the present invention, the resin material forming the base layer is different from the resin material forming the infrared radiation layer, in other words, any one of polyester-based resin, acrylic-based resin, and urethane-based resin. As described above, by using one of polyester resin, acrylic resin, and urethane resin as the resin material for the substrate layer, damage to the substrate is minimized when copper is vapor-deposited, enabling the formation of a uniform reflective layer, which is desirable for achieving a high and uniform reflectivity across the entire surface. Conversely, using PVC or other materials for the substrate is undesirable because outgassing occurs due to substrate damage during vapor deposition, preventing the metal layer from being formed uniformly.

[0019] Further features of the combined cooling device include: The resin material forming the infrared radiation layer contains at least one of polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, and polyvinylidene fluoride.

[0020] According to the above characteristic configuration, infrared light can be appropriately radiated to the atmospheric window, thereby effectively exerting the radiative cooling function.

[0021] Further features of the combined cooling device include: The white filler accounts for 0.1% by mass or more and 40% by mass or less of the mass of the infrared radiation layer and the base layer containing the white filler.

[0022] As in the above characteristic configuration, the mass ratio of the white filler to the volume of the infrared radiation layer and the base layer containing the white filler is preferably 0.1 mass % or more and 40 mass % or less. If the mass proportion of the white filler is less than 0.1 mass%, the visible light reflectance decreases, and cooling performance cannot be obtained. If it exceeds 40 mass%, the pigment concentration is too high, which can result in poor film-forming properties in R2R, loss of flexibility, and the emissive layer becoming more susceptible to tearing after long-term use.

[0023] Further features of the combined cooling device include: In a configuration in which at least one of the infrared radiation layer and the base layer contains at least one of the white filler and the pores, The infrared radiation layer and the base layer have an average reflectance of 70% or more in the visible light region with wavelengths of 400 nm to 800 nm.

[0024] As in the above-described characteristic configuration, in a configuration in which at least one of the infrared radiation layer and the base layer contains either a white filler or voids, the average reflectance of the infrared radiation layer and the base layer in the visible light region of wavelengths from 400 nm to 800 nm is 70% or more, and therefore even when copper or a copper alloy is used as the light-reflecting layer, light in the visible light region to the infrared light region can be well reflected, and the radiative cooling function can be appropriately exhibited.

[0025] Further features of the combined cooling device include: a protective layer is provided on the side of the light reflecting layer opposite to the side on which the base layer is present, The protective layer contains an anticorrosive agent containing at least one of thiazole, imidazole, benzotriazole, and a chromic acid-based compound.

[0026] Further features of the combined cooling device include: The substrate layer contains an anticorrosive agent containing thiazole, imidazole, benzotriazole, and a chromic acid-based compound.

[0027] For example, when a light-reflecting layer made of copper or a copper alloy is used without any protective structure, as in the composite cooling device disclosed in Patent Document 2, it is easily oxidized when hydrogen or oxygen is supplied from the outside. According to the above characteristic configuration, by protecting the light-reflecting layer made of copper or a copper alloy with a layer containing at least one of thiazole, imidazole, benzotriazole, and a chromic acid-based compound, which exhibits anticorrosion properties for copper or a copper alloy, it is possible to prevent oxidation of the light-reflecting layer for a long period of time and maintain high reflectivity.

[0028] Further features of the combined cooling device include: At least one of the first connection layer, which serves as a connection layer connecting the infrared radiation layer and the base material layer, and the second connection layer, which connects the base material layer and the light-reflecting layer, contains at least one of a white filler and hollow particles.

[0029] In particular, as described above, by incorporating fillers or hollow particles having an arithmetic mean particle size of, for example, about 0.1 μm or more and 5 μm or less into the connecting layer, the reflectance of light in the ultraviolet to visible region can be improved, and the thickness of the laminated resin layer (particularly the light-reflecting layer) can be reduced to obtain the desired reflectance.

[0030] Further features of the combined cooling device include: The light-reflecting layer has an average reflectance of 80% or more in the infrared light region with wavelengths of 800 nm to 1200 nm.

[0031] As described above, since the light-reflecting layer has an average reflectance of 80% or more in the infrared light range with wavelengths of 800 nm or more and 1200 nm or less, the composite cooling device can effectively reflect light from the visible light range to the infrared light range, and can properly perform its radiative cooling function.

[0032] The features of the manufacturing method of the composite cooling device explained so far are: the substrate layer is polyethylene terephthalate containing the white filler, The metal is vapor-deposited onto the substrate layer to form the light-reflecting layer.

[0033] The inventors have confirmed that even when the substrate layer is polyethylene terephthalate containing a white filler, a light-reflecting layer can be formed satisfactorily by vapor-depositing a metal such as copper or a copper alloy onto the substrate layer. [Brief explanation of the drawings]

[0034] [Figure 1] 1A and 1B are diagrams illustrating an embodiment of a combined cooling device. [Figure 2] 1A and 1B are diagrams illustrating an embodiment of a combined cooling device. [Figure 3] 1A and 1B are diagrams illustrating an embodiment of a combined cooling device. [Figure 4] FIG. 10 is a diagram showing the relationship between the absorption coefficient of a resin material and a wavelength band. [Figure 5] FIG. 10 is a diagram showing the relationship between the light absorptance of a resin material and wavelength. [Figure 6] FIG. 1 is a diagram showing the emissivity spectrum of vinyl chloride resin. [Figure 7] FIG. 1 is a diagram showing the emissivity spectrum of vinylidene chloride resin. [Figure 8] FIG. 1 is a diagram showing the emissivity spectrum of ethylene terephthalate resin. [Figure 9] FIG. 10 is a diagram showing the relationship between the temperature of the radiation surface and the temperature of the light reflecting layer. [Figure 10] FIG. 10 is a diagram showing an example of a stacking configuration of a composite cooling device of a comparative example. [Figure 11] FIG. 10 is a diagram showing an example of a stacking configuration of a composite cooling device of a comparative example. [Figure 12] FIG. 10 is a diagram showing an example of a stacking configuration of a composite cooling device of a comparative example. [Figure 13] 10A and 10B are diagrams illustrating another embodiment of the combined cooling device. DETAILED DESCRIPTION OF THE INVENTION

[0035] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. [Basic configuration of the combined cooling system] As shown in Fig. 1, the composite cooling device CP includes an infrared emitting layer J that radiates infrared light IR from an emitting surface H, and a light reflecting layer B that is located on the infrared emitting layer J on the side opposite to the side where the emitting surface H exists, and is formed in the shape of a film. In other words, the composite cooling device CP is configured as a radiative cooling film. To further explain, the composite cooling device CP according to this embodiment has a light-reflecting layer B that is 50 nm or more and 500 nm or less in thickness and is made of a metal containing 50% to 100% by mass of copper, and has a base material layer BA formed of a resin material between the infrared radiation layer J and the light-reflecting layer B, and is configured so that at least one of the infrared radiation layer J and the base material layer BA contains at least one of white filler F having an arithmetic mean particle diameter of 2 μm or less and pores (not shown) having an arithmetic mean pore diameter of 0.01 μm or more and 2 μm or less. The arithmetic mean particle size of the white filler F is more preferably 0.2 μm or more and 1 μm or less. The light-reflecting layer B has an average reflectance of 80% or more in the infrared light region with wavelengths of 800 nm or more and 1200 nm or more.

[0036] In this embodiment, light L includes ultraviolet light, visible light, and infrared light, and when these are described in terms of the wavelength of light as electromagnetic waves, they include electromagnetic waves with wavelengths of 10 nm to 20,000 nm (electromagnetic waves of 0.01 μm to 20 μm). The solar spectrum exists in the wavelength range from 300 nm to 4000 nm, and the intensity increases as the wavelength increases from 400 nm, and the intensity is particularly high in the wavelength range from 500 nm to 1800 nm.

[0037] In the composite cooling device CP of this embodiment, the infrared radiation layer J and the base material layer BA are connected by a first connection layer S1 as a connection layer S, and the base material layer BA and the light reflecting layer B are connected by a second connection layer S2 as a connection layer S. Furthermore, a protective layer HO is provided on the side of the light reflecting layer B opposite to the side where the base layer BA is present.

[0038] That is, in the composite cooling device CP according to this embodiment, as shown in Figures 1 to 3, an infrared radiation layer J, a first connection layer S1, a base material layer BA, a second connection layer S2, a light-reflecting layer B, and a protective layer HO are stacked in this order from the radiation surface H side. As shown in FIG. 1, the white filler F may be contained only in the base layer BA, as shown in FIG. 2, the white filler F may be contained in both the infrared emitting layer J and the base layer BA, or as shown in FIG. 3, the white filler F may be contained only in the infrared emitting layer J. Furthermore, although not shown, in the composite cooling device CP shown in Figures 1 to 3, pores may be contained only in the base material layer BA, or pores may be contained in both the infrared radiation layer J and the base material layer BA, or pores may be contained only in the infrared radiation layer J. As an example, as shown in FIG. 13, the infrared emitting layer J may not contain the white filler F and the pores, and only the base layer BA may contain the white filler F and the pores K.

[0039] However, from the viewpoint of ensuring good infrared radiation by the infrared radiation layer J, it is preferable that the infrared radiation layer J does not contain pores. By including pores in the infrared radiation layer J, it is possible to suitably prevent dirt from adhering to the radiation surface H of the infrared radiation layer J, which is often exposed to the outside. Furthermore, it is possible to increase the volume ratio of the resin material in the infrared radiation layer J and reduce the thickness of the infrared radiation layer J.

[0040] The connection layer S is made of at least one of an adhesive, a pressure-sensitive adhesive, and a glue. Specific materials suitable for use in the connection layer S include acrylic adhesives, urethane adhesives, and silicone adhesives. Although not shown, the connection layer S contains at least one of a white filler F and hollow particles, which can improve the reflectance of light in the ultraviolet to visible region and reduce the thickness of the composite cooling device CP (particularly the light-reflecting layer B) to achieve the desired reflectance. The white filler and hollow particles preferably have an arithmetic mean particle diameter of approximately 0.1 μm to 5 μm. Granulated TiO2, MgSO4, BaSO4, and TiBaO3 are suitable white fillers. This improves the reflectance of light in the ultraviolet to visible region, and reduces the thickness of the complex cooling device CP (particularly the light reflecting layer B) to obtain a desired reflectance.

[0041] The substrate layer BA and the protective layer HO may contain an anticorrosive agent, which may be at least one of thiazole, imidazole, benzotriazole, and a chromic acid compound.

[0042] With the above configuration, the composite cooling device CP reflects a portion of the light L incident on the composite cooling device CP by the radiation surface H of the infrared radiation layer J. Furthermore, in addition to reflecting the light L incident on the composite cooling device CP by the light reflecting layer B, if the infrared radiation layer J includes at least one of a white filler F and voids, the light L is reflected by the infrared radiation layer J, and if the base layer BA includes at least one of a white filler F and voids, the light is reflected by the light reflecting layer B and is allowed to escape to the outside from the radiation surface H.

[0043] The composite cooling device CP is configured to cool an object to be cooled (not shown) located on the opposite side of the light reflecting layer B from the side where the infrared radiation layer J is present, by converting heat input to the composite cooling device CP (for example, heat input due to thermal conduction from the object to be cooled) into infrared light IR by the infrared radiation layer J and radiating it.

[0044] In other words, the composite cooling device CP is configured to reflect light L irradiated onto the composite cooling device CP and to radiate heat transferred to the composite cooling device CP (for example, heat transferred from the atmosphere or from the object to be cooled) to the outside as infrared light IR. Furthermore, the infrared radiative layer J and the light reflecting layer B are flexible, so that the composite cooling device CP (radiative cooling film) is configured to be flexible.

[0045] In addition, the composite cooling device CP is used to implement a radiative cooling method in which infrared light IR is radiated from a radiation surface H opposite to the surface of the infrared radiation layer J that is in contact with the light-reflecting layer B. Specifically, the radiation surface H is directed toward the sky, and the radiation cooling method is implemented in which infrared light IR is radiated from the radiation surface H that faces the sky.

[0046] [Resins forming the infrared radiation layer and the base layer] The resin forming the infrared radiation layer J may be a colorless resin material containing a carbon-fluorine bond (CF) or a carbon-chlorine bond (C—Cl). The resin forming the base layer BA can be a colorless resin material containing a carbon-oxygen bond (CO), an ester bond (R-COO-R), an ether bond (COC bond), or a benzene ring. For each resin material (excluding carbon-oxygen bonds), the wavelength ranges with absorption coefficients in the atmospheric window wavelength band are shown in Figure 3.

[0047] According to Kirchhoff's law, emissivity (ε) and light absorptance (A) are equal. Light absorptance can be calculated from the absorption coefficient (α) using the equation A=1-exp(-αt) (hereafter referred to as the light absorptance equation), where t is the film thickness. In other words, by adjusting the film thickness of the infrared radiation layer J, it is possible to obtain a large thermal radiation in a wavelength band with a large absorption coefficient. When performing radiative cooling outdoors, it is recommended to use a material with a large absorption coefficient in the wavelength band of 8 μm to 13 μm, which is the atmospheric window. In addition, to suppress the absorption of sunlight, it is advisable to use a material that has no or a small absorption coefficient in the wavelength range of 0.3 μm to 4 μm, especially in the range of 0.4 μm to 2.5 μm. As can be seen from the relationship between the absorption coefficient and absorptance, the light absorptance (emissivity) changes depending on the film thickness of the resin material.

[0048] In order to lower the temperature below the surrounding atmosphere through radiative cooling in a solar radiation environment, if a material is selected that has a large absorption coefficient in the wavelength band of the atmospheric window and almost no absorption coefficient in the wavelength band of sunlight, then by adjusting the film thickness, it will absorb almost no sunlight but emit a lot of thermal radiation from the atmospheric window, meaning that it is possible to create a state in which the output from radiative cooling is greater than the input of sunlight.

[0049] Regarding carbon-fluorine bonds (CF), the absorption coefficients due to CHF and CF2 are widely distributed over a wide wavelength band from 8 μm to 13 μm, which is the atmospheric window, with a particularly large absorption coefficient at 8.6 μm. In addition, in the solar wavelength band, there is no significant absorption coefficient in the wavelength range from 0.3 μm to 2.5 μm, where the energy intensity is high.

[0050] Resin materials with carbon-fluorine bonds (CF) include: Examples include polyvinyl fluoride (PVD) and polyvinylidene fluoride (PVDF). In the following, polyvinyl fluoride may be referred to as vinylyl fluoride resin, but the two terms refer to the same material. The same applies to other resins.

[0051] For carbon-chlorine bonds (C-Cl), the absorption coefficient due to the C-Cl stretching vibration appears in a broad band with a half-width of 1 μm or more centered at a wavelength of 12 μm. Resin materials include polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC). In the case of polyvinyl chloride, the electron-withdrawing effect of chlorine causes an absorption coefficient at a wavelength of around 10 μm that is derived from the bending vibration of the CH of the alkene contained in the main chain.

[0052] Ester bonds (R-COO-R) and ether bonds (COC bonds) have absorption coefficients in the wavelength range of 7.8 μm to 9.9 μm. In addition, the carbon-oxygen bonds contained in ester bonds and ether bonds have strong absorption coefficients in the wavelength range of 8 μm to 10 μm. When a benzene ring is introduced into the side chain of a hydrocarbon resin, absorption appears over a wide wavelength range from 8.1 μm to 18 μm due to the vibration of the benzene ring itself and the vibration of surrounding elements caused by the influence of the benzene ring.

[0053] Resins having these bonds include ethylene terephthalate resins and polymethyl methacrylate resins.

[0054] [Considerations of light absorption] Let us consider the light absorption in the ultraviolet-visible region of resin materials with the bonds and functional groups described above, i.e., sunlight absorption. The origin of the absorption of ultraviolet to visible light is the transition of electrons that contribute to the bond. Absorption in this wavelength range can be understood by calculating the bond energy. First, let's consider the wavelengths at which resin materials with carbon-fluorine bonds (CF) have absorption coefficients in the ultraviolet to visible range. The bond energies of the CC, CH, and CF bonds in the basic structural parts of polyvinylidene fluoride (PVDF) are 4.50 eV, 4.46 eV, and 5.05 eV. These correspond to wavelengths of 0.275 μm, 0.278 μm, and 0.246 μm, respectively, and light of these wavelengths is absorbed.

[0055] Since the solar spectrum only contains wavelengths longer than 0.300 μm, when fluororesin is used, it hardly absorbs the ultraviolet, visible, or near-infrared rays of sunlight. Note that ultraviolet rays are defined as wavelengths shorter than 0.400 μm, visible light is defined as wavelengths from 0.400 μm to 0.800 μm, near-infrared rays are defined as wavelengths from 0.800 μm to 3 μm, mid-infrared rays are defined as wavelengths from 3 μm to 8 μm, and far-infrared rays are wavelengths longer than 8 μm.

[0056] Regarding the carbon-chlorine bond (C-Cl), the bond energy between carbon and chlorine in alkenes is 3.28 eV, and the wavelength is 0.378 μm, so they absorb a lot of ultraviolet light in sunlight, but have almost no absorption in the visible range. Figure 5 shows the absorption spectrum of a 100 μm thick vinyl chloride resin in the ultraviolet to visible region, and shows that light absorption increases at wavelengths shorter than 0.38 μm. Figure 5 shows the absorption spectrum of a 100 μm thick vinylidene chloride resin in the ultraviolet to visible region, and shows a slight increase in the absorption spectrum on the shorter wavelength side than 0.4 μm.

[0057] Resins with ester bonds (R-COO-R), ether bonds (C-O-C bonds), and benzene rings include methyl methacrylate resin and ethylene terephthalate resin. For example, the bond energy of the C-C bond in acrylic is 3.93 eV, and it absorbs sunlight with wavelengths shorter than 0.315 μm, but has almost no absorption in the visible range.

[0058] As an example of a resin material having these bonds and functional groups, the absorbance spectrum from ultraviolet to visible light of a 5 mm thick methyl methacrylate resin is shown in Figure 5. The methyl methacrylate resin shown here is a commonly available product on the market, and contains a benzotriazole-based ultraviolet absorber. Because the plate is 5 mm thick, the wavelengths with small absorption coefficients are also large, and light absorption is greater on the shorter wavelength side than 0.38 μm, which is longer than the wavelength of 0.315 μm.

[0059] As an example of a resin material having these bonds and functional groups, the absorption spectrum from ultraviolet to visible light of a 40 μm thick ethylene terephthalate resin is shown in FIG. As shown in the figure, the absorptance increases as the wavelength approaches 0.315 μm, and absorbance increases sharply at a wavelength of 0.315 μm. Note that with ethylene terephthalate resin, as the thickness increases, the absorptance due to the absorption edge derived from C-C bonds increases at wavelengths slightly longer than 0.315 μm, and similar to methyl methacrylate resin, the absorptance in ultraviolet light increases.

[0060] The infrared radiation layer J may be a single layer film made of one type of resin material, a multilayer film made of multiple types of resin materials, a single layer film made of a resin material in which multiple types of resin materials are blended, or a multilayer film made of a resin material in which multiple types of resin materials are blended, as long as it is made of a resin material having the above-mentioned emissivity (light emissivity) and light absorptivity properties. The blends also include copolymers such as alternating copolymers, random copolymers, block copolymers and graft copolymers, as well as modified products with substituted side chains.

[0061] [Emissivity of vinyl chloride resin and vinylidene chloride resin] Figure 6 shows the emissivity of polyvinyl chloride resin (PVC) at the atmospheric window, as a representative example of resins with carbon-chlorine bonds. Figure 7 shows the emissivity of polyvinylidene chloride resin (PVDC) at the atmospheric window. Regarding the carbon-chlorine bond, the absorption coefficient due to the C-Cl stretching vibration appears in a broad band with a half-width of 1 μm or more centered at a wavelength of 12 μm. In addition, in the case of vinyl chloride resin, the electron-withdrawing effect of chlorine causes an absorption coefficient at a wavelength of around 10 μm, which is due to the bending vibration of the CH of the alkene contained in the main chain. The same is true for vinylidene chloride resin. Due to these effects, the wavelength average of the emissivity for a 10 μm thick film is 43% at wavelengths from 8 μm to 13 μm, which falls within the wavelength average of 40% or more. As shown in the figure, the emissivity in the atmospheric window region increases as the film thickness increases.

[0062] [Emissivity of ethylene terephthalate resin] Figure 8 shows the emissivity of ethylene terephthalate resin in the atmospheric window as a typical example of a resin having an ester bond or a benzene ring. Ester bonds have an absorption coefficient in the wavelength range of 7.8 μm to 9.9 μm. Furthermore, the carbon-oxygen bond contained in the ester bond exhibits a strong absorption coefficient in the wavelength range of 8 μm to 10 μm. When a benzene ring is introduced into the side chain of a hydrocarbon resin, a wide range of absorption appears in the wavelength range of 8.1 μm to 18 μm due to the vibration of the benzene ring itself and the vibration of surrounding elements caused by the influence of the benzene ring. Due to these effects, the wavelength average of the emissivity for a 10 μm thick film is 71% at wavelengths from 8 μm to 13 μm, which falls within the wavelength average of 40% or more. As shown in the figure, the emissivity in the atmospheric window region increases as the film thickness increases.

[0063] [Surface temperature of light reflecting layer and infrared emitting layer] The thermal radiation of the atmospheric window of the infrared radiation layer J occurs near the surface of the resin material. Figure 6 shows that in the case of vinyl chloride resin, even if the thickness exceeds 100 μm, there is almost no increase in thermal radiation in the atmospheric window region. In other words, in the case of vinyl chloride resin, thermal radiation in the atmospheric window occurs within a depth of approximately 100 μm from the surface, and radiation from deeper parts does not escape to the outside. From FIG. 7, it can be seen that vinylidene chloride resin is similar to vinyl chloride resin.

[0064] As can be seen from Figure 8, in the case of ethylene terephthalate resin, even if the thickness exceeds 125 μm, there is almost no increase in thermal radiation in the atmospheric window region. In other words, in the case of ethylene terephthalate resin, thermal radiation in the atmospheric window occurs at a depth of approximately 100 μm from the surface, and radiation from deeper parts does not escape to the outside.

[0065] As described above, the thermal radiation from the atmospheric window region generated from the surface of the resin material occurs within a depth of approximately 100 μm from the surface. If the resin thickness increases beyond this, the cold generated by the radiative cooling of the combined cooling device is insulated by the resin material, which does not contribute to thermal radiation. Ideally, the infrared emitting layer J and the base material layer BA are made of a resin that does not absorb sunlight at all, and the infrared emitting layer J and the base material layer BA are fabricated on the light reflecting layer B. In this case, sunlight is absorbed only by the light reflecting layer B of the complex cooling device CP. The thermal conductivity of resin materials is generally about 0.2 W / m / K. When this thermal conductivity is taken into account, calculations show that if the thickness of the infrared radiation layer J exceeds 20 mm, the temperature of the cooling surface (the surface of the light-reflecting layer B opposite to the side where the infrared radiation layer J is present) will rise.

[0066] Even if an ideal resin material existed that did not absorb any sunlight, the thermal conductivity of the resins of the infrared radiation layer J and base layer BA would generally be around 0.2 W / m / K, so if the thickness exceeds 20 mm as shown in Figure 9, the light-reflecting layer B would be heated by sunlight, and the object to be cooled placed on the side of the light-reflecting layer B would be heated. In other words, the combined thickness of the resin of the infrared radiation layer J and base layer BA needs to be 20 mm or less.

[0067] Figure 9 shows the surface temperature of the radiative surface H and the temperature of the light-reflecting layer B of the composite cooling device (radiative cooling film), calculated assuming a clear day in the west of Japan in midsummer at noon. The sunlight is AM1.5, 1000W / m 2 The outside temperature is 30°C, and the radiant energy varies depending on the temperature, but is 100W at 30°C. This calculation assumes that the infrared radiant layer J and the base material layer BA do not absorb sunlight. Assuming no wind, the convective heat transfer coefficient is 5W / m 2 / K.

[0068] [Light absorption of hydrocarbon resins] When the resin material forming the infrared radiation layer J or the base layer BA is a resin having a main chain made of a hydrocarbon having one or more carbon-chlorine bonds, carbon-oxygen bonds, ester bonds, ether bonds, or benzene rings, or when the resin material is a silicone resin having two or more carbon atoms in the hydrocarbon side chain, absorption due to vibrations such as bond bending and stretching is observed in the near-infrared region in addition to the ultraviolet absorption due to the covalent bond electrons described above.

[0069] Specifically, absorption due to the fundamental tones of the transitions to the first excited states of CH3, CH2, and CH appears at wavelengths of 1.6 μm to 1.7 μm, 1.65 μm to 1.75 μm, and 1.7 μm, respectively. Furthermore, absorption due to the fundamental tones of the combination tones of CH3, CH2, and CH appears at wavelengths of 1.35 μm, 1.38 μm, and 1.43 μm, respectively. Furthermore, overtones of the transitions to the second excited states of CH2 and CH appear at wavelengths around 1.24 μm. The fundamental tones of the bending and stretching of the C-H bond are distributed over a wide band from 2 μm to 2.5 μm.

[0070] Furthermore, when an ester bond (R-COO-R) or an ether bond (COC) is present, there is a large optical absorption at a wavelength of around 1.9 μm. According to the above-mentioned optical absorptance relational expression, the optical absorptance caused by these factors becomes smaller and less noticeable when the resin material film is thin, but becomes larger when the film is thick.

[0071] [Light absorption of blend resins] When the resin is a resin material that is a blend of a resin whose main chain is a carbon-fluorine bond and a resin whose main chain is a hydrocarbon, light absorption in the near-infrared region due to CH, CH2, CH3, etc. appears depending on the proportion of the blended resin whose main chain is a hydrocarbon. When the main component is carbon-fluorine bonds, the optical absorption in the near-infrared region caused by hydrocarbons is small, so the thickness can be increased up to 20 mm, which is the upper limit from the viewpoint of thermal conductivity.

[0072] The blend of fluororesin and hydrocarbon also includes those in which the fluororesin is substituted with hydrocarbon, and alternating copolymers, random copolymers, block copolymers and graft copolymers of fluoromonomers and hydrocarbon monomers.

[0073] Depending on the molecular weight and proportion of the hydrocarbon side chains substituted, optical absorption in the near-infrared region due to CH, CH2, CH3, etc. appears. When the monomers introduced as side chains or copolymers are low molecular weight, or when the density of the introduced monomers is low, optical absorption in the near-infrared region due to hydrocarbons becomes small, so the thickness can be increased up to 20 mm, which is the limit from the viewpoint of thermal conductivity.

[0074] [Thickness of the infrared radiation layer] From the viewpoint of practical use of the composite cooling device CP, it is preferable that the thickness of the infrared radiation layer J is thin. The thermal conductivity of resin materials is generally lower than that of metals, glass, etc. In order to effectively cool the object to be cooled, it is preferable that the thickness of the infrared radiation layer J is kept to the minimum necessary. The thicker the thickness of the infrared radiation layer J, the greater the thermal radiation from the atmospheric window, and once a certain thickness is exceeded, the thermal radiation energy from the atmospheric window becomes saturated.

[0075] The thickness at which the film saturates depends on the resin material, but in the case of fluororesin, saturation is generally sufficient at around 300 μm. Therefore, from the perspective of thermal conductivity, it is preferable to keep the film thickness below 300 μm rather than 500 μm. Furthermore, although thermal radiation does not saturate, even a thickness of around 100 μm can provide sufficient thermal radiation in the atmospheric window region. The thinner the thickness, the higher the thermal conductivity and the more effectively the temperature of the object being cooled can be lowered, so in the case of fluororesin, it is best to keep the thickness below around 100 μm.

[0076] The absorption coefficients resulting from carbon-silicon bonds, carbon-chlorine bonds, carbon-oxygen bonds, ester bonds, and ether bonds are greater than the absorption coefficient resulting from C—F bonds. Naturally, from the perspective of thermal conductivity, it is preferable to keep the film thickness to 300 μm or less rather than 500 μm, but an even greater radiative cooling effect can be expected if the film thickness is made even thinner and thermal conductivity is increased. In the case of resins containing carbon-chlorine bonds, saturation occurs even at a thickness of 100 μm, and sufficient thermal radiation is obtained in the atmospheric window region even at a thickness of 50 μm. The thinner the resin material, the higher the thermal conductivity and the more effectively the temperature of the object being cooled can be lowered, so in the case of resins containing carbon-chlorine bonds, a thickness of 50 μm or less reduces the insulating properties and allows the object to be cooled effectively. In the case of carbon-chlorine bonds, a thickness of 100 μm or less allows the object to be cooled effectively.

[0077] The benefit of making the material thinner is not just that it reduces heat insulation and makes it easier to transfer cold. It also reduces the absorption of near-infrared light from CH, CH2, and CH3, which are present in resins containing carbon-chlorine bonds. By making the material thinner, it is possible to reduce the amount of sunlight absorbed by these compounds, thereby increasing the cooling capacity of the composite cooling device CP. From the above perspective, in the case of resins containing carbon-chlorine bonds, a thickness of 50 μm or less can more effectively produce a radiative cooling effect under sunlight.

[0078] As will be described later, in the composite cooling device CP according to this embodiment, a resin is also used for the base material layer BA, and a certain level of heat radiation can be expected. In consideration of this point, it is preferable to further reduce the thickness of the infrared radiation layer J described above.

[0079] [Details of the light-reflecting layer] As described above, the composite cooling device CP according to this embodiment has an economic advantage over using a metal mainly made of silver (silver or silver alloy) as the light reflecting layer B by using a metal mainly made of copper as the light reflecting layer B. Furthermore, it has been confirmed through tests described below that by using a metal mainly made of copper, even when a relatively thick light reflecting layer B is formed by vapor deposition on an infrared radiation layer J made of a resin material, it is possible to reduce the entrapment of the resin material due to heat. More specifically, the light reflecting layer B is made of a metal (copper or copper alloy) containing 50% by mass or more and 100% by mass or less of copper, and has a thickness of 50 nm or more and 500 nm or less.

[0080] As mentioned above, the light-reflecting layer B is made of a metal whose main material is copper, and therefore has a low reflectance in the visible light range, making it difficult for the light-reflecting layer B alone to perform the light-reflecting function of the composite cooling device CP. Therefore, the complex cooling device CP according to this embodiment includes a base material layer BA described below.

[0081] [Details of base layer] In the composite cooling device CP according to this embodiment, the base material layer BA is preferably made of a resin material containing at least one of polyester resin, acrylic resin, and urethane resin, and further, as shown in Figures 1 and 2, it is preferable that the base material layer BA contains a second white filler F2 as a white filler F having an arithmetic mean particle diameter of 2 μm or less.

[0082] The mass proportion of the second white filler F2 in the base layer BA is preferably 0.1 mass % or more and 40 mass % or less.

[0083] The base layer BA may contain pores having an arithmetic mean pore diameter of 0.01 μm or more and 2 μm or less instead of the second white filler F2. The base layer BA may also contain the pores in addition to the second white filler F2.

[0084] Incidentally, the base material layer BA does not necessarily need to contain at least one of the second white filler F2 and the voids described above, and as shown in the composite cooling device CP in Figure 3, a configuration may be adopted in which the infrared radiation layer J contains at least one of the first white filler F1 as the white filler F and the voids. The first white filler F1 contained in the infrared emitting layer J may be the same as or different from the first white filler F1(F) contained in the base material layer BA. The pores contained in the infrared emitting layer J may be the same as or different from the pores contained in the base material layer BA.

[0085] When the base layer BA does not contain a white filler F and the infrared emitting layer J contains a white filler F (and / or pores), the following mass ratios are preferred.

[0086] The mass proportion of the first white filler F1 in the infrared radiation layer J is preferably 0.1 mass % or more and 40 mass % or less.

[0087] The infrared emitting layer J may contain the voids instead of the first white filler F1. The infrared emitting layer J may also contain the voids in addition to the first white filler F1.

[0088] The mass proportion of the white filler F in the volume of the infrared radiation layer J and the base layer BA containing the white filler F is preferably 0.1 mass % or more and 40 mass % or less.

[0089] By adopting the above configuration, the combined cooling device CP according to this embodiment achieves a configuration with an average reflectance of 70% or more in the visible light range of wavelengths from 400 nm to 800 nm, due to the infrared radiation layer J and base material layer BA, which are layers other than the light reflecting layer B. Note that the average reflectance in the visible light range is the reflectance in a configuration that does not include the light reflecting layer B, and the average reflectance in the visible light range in a configuration that includes the light reflecting layer B is 80% or more.

[0090] Furthermore, in a configuration in which the connecting layer S contains white filler F or hollow beads, the composite cooling device CP according to this embodiment achieves a configuration in which the average reflectance in the visible light range of wavelengths from 400 nm to 800 nm is 80% or more by the infrared radiation layer J, the base material layer BA, and the connecting layer S, which are layers other than the light reflecting layer B. Note that the average reflectance in the visible light range is the reflectance in a configuration that does not include the light reflecting layer B, and the average reflectance in the visible light range in a configuration that includes the light reflecting layer B is 80% or more.

[0091] [Combination of Resin Materials for Infrared Radiation Layer and Base Material Layer] As explained above, it is preferable that the resin material forming the infrared radiation layer J contains at least one of polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, and polyvinylidene fluoride, and it is preferable that the resin material forming the base material layer BA contains at least one of polyester-based resin, acrylic-based resin, and urethane-based resin. The reason why the resin material for the infrared radiation layer J and the base layer BA was selected in this way is that it has very high emissivity in the wavelength range of 8 to 13 μm and also has excellent long-term weather resistance.

[0092] Incidentally, it is preferable that the average reflectance of the infrared radiation layer J and the base layer BA in the visible light region with wavelengths of 400 nm to 800 nm is 70% or more.

[0093] From the viewpoint of improving the infrared emissivity and especially the reflectivity of light in the visible light region, a suitable combination of the resin material of the infrared emitting layer J and the resin material of the base layer BA is polyvinyl chloride and polyethylene terephthalate.

[0094] Preferably, the base layer BA is polyethylene terephthalate containing a white filler F, and the light reflecting layer B is formed by depositing a metal containing 50% by mass to 100% by mass of copper onto the base layer BA.

[0095] [Proportion of white filler (and / or voids) in the infrared radiation layer and base layer] When the white filler F (or / and voids) is contained in both the infrared radiation layer J and the base layer BA, from the viewpoint of improving the infrared emissivity and, in particular, the reflectivity of light in the visible light region, the ratio of the mass of the white filler F (or / and voids) contained in the infrared radiation layer J to the mass of the white filler F (or / and voids) contained in the base layer BA is preferably 0.1 mass% or more and 40 mass% or less.

[0096] The composite cooling device CP according to this embodiment, with the configuration described above, has a visible light reflectance of 80% or more for wavelengths of 400 nm to 800 nm, an infrared reflectance of 80% or more for wavelengths of 800 nm to 1200 nm, an arithmetic mean of infrared emissivity of 90% or more for wavelengths of 8 μm to 13 μm, a certain level of planar thermal conductivity, and can sufficiently suppress coloration due to aggregation.

[0097] [Experimental results] For the combined cooling examples and comparative examples described so far, various tests were conducted on the visible light reflectance in the wavelength range of 400 nm to 800 nm, the infrared light reflectance in the wavelength range of 800 nm to 1200 nm, the infrared emissivity, the planar thermal conductivity, the metal layer imparting property, and the coloring property due to condensation, and the results are shown in the following Tables 1 to 4. In the test results shown in the tables, the underlined parts indicate that the conditions of the various tests were not met. Incidentally, Tables 1 to 4 also show various conditions for the films constituting the Examples and Comparative Examples. In addition, Examples 1, 3, 4, 8, and 9 relate to the stacking configuration shown in Figure 3, Examples 5, 6, and 7 relate to the stacking configuration shown in Figure 2, and Example 2 relates to the stacking configuration shown in Figure 1. The materials of each layer constituting the composite cooling device CP are as shown in Tables 1 and 2. On the other hand, Comparative Examples 1, 2, 5, 6, and 8 relate to the stacking configuration shown in Fig. 10, Comparative Examples 3 and 4 relate to the stacking configuration shown in Fig. 11, and Comparative Example 7 relates to the stacking configuration shown in Fig. 12, and the materials of each layer constituting the combined cooling device are as shown in Tables 3 and 4. For convenience of explanation, the white filler is not shown in Figs. 10 to 12.

[0098] The visible light reflectance in the wavelength range of 400 to 800 nm was evaluated using the arithmetic mean of the reflectance in the wavelength range of 400 to 800 nm measured using a UV-Visible Spectrometer UV-2600 (Shimadzu Corporation). A reflectance of 80% or higher was defined as satisfying the condition (high reflectance in the wavelength range of 400 to 800 nm).

[0099] The infrared reflectance in the wavelength range of 800 to 1200 nm was evaluated using the arithmetic mean of the reflectance in the wavelength range of 800 to 1200 nm measured using a UV-Visible Spectrometer UV-2600 (Shimadzu Corporation). Products with an infrared reflectance of 80% or higher were defined as meeting the condition (high reflectance in the wavelength range of 800 to 1200 nm).

[0100] Infrared emissivity was evaluated using the arithmetic mean of emissivity at wavelengths from 8 μm to 13 μm measured using an FT-IR IRTracer-100 (Shimadzu Corporation). Products with an emissivity of 90% or higher were defined as meeting the criteria.

[0101] The planar thermal conductivity was measured using the laser flash method defined in JIS R1611, and the value in Example 1 was defined as 1.0, and values ​​above this value were defined as high (good) planar thermal conductivity.

[0102] No color change due to aggregation is confirmed by the xenon weather resistance test defined in JIS K5600, in an environment with a black panel temperature (BPT) of 63°C, a wavelength of 550 nm, and an intensity of 180 W / m 2 The sample was exposed to ultraviolet light for 4000 hours, and the color difference ΔE of the sample before and after the test was measured. A value of ΔE<2.0 was defined as no color change due to aggregation (good).

[0103] [Table 1]

[0104] [Table 2]

[0105] [Table 3]

[0106] [Table 4]

[0107] As shown in the above experimental results, the composite cooling devices CP according to Examples 1 to 9 of the present invention have achieved results that satisfy the specified conditions with respect to visible light reflectance in the wavelength range of 400 nm to 800 nm, infrared light reflectance in the wavelength range of 800 nm to 1200 nm, infrared emissivity, planar thermal conductivity, metal layer imparting ability, and coloring due to condensation.

[0108] On the other hand, in Comparative Examples 3 and 5, the condition for visible light reflectance is thought to be met mainly because the base layer BA does not contain a white filler; in Comparative Example 7, the condition for infrared reflectance is thought to be met mainly because the light-reflecting layer B is not provided; in Comparative Examples 3, 4, and 7, the condition for infrared emissivity is thought to be met mainly because the infrared radiation layer J is not provided; in Comparative Examples 5 and 7, the condition for planar thermal conductivity is thought to be met mainly because the thickness of the copper alloy constituting the light-reflecting layer B is thin; in Comparative Example 6, the condition for metal impartation is thought to be met mainly because the silver alloy, which requires a relatively high deposition temperature, is made relatively thick at 500 nm; and in Comparative Examples 1, 2, 4, 6, and 8, the condition for coloration due to condensation is thought to be met mainly because the metal material constituting the light-reflecting layer B contains silver (coloration occurred due to condensation). In Comparative Example 5, the thickness of the light-reflecting layer is as thin as 20 nm, and therefore, sufficient reflectance cannot be obtained.

[0109] That is, from the viewpoint of suppressing coloration due to aggregation of metals, it is preferable that the copper alloy does not contain silver.

[0110] [Another embodiment] (1) In the above embodiment, the protective layer HO does not necessarily have to be provided.

[0111] Furthermore, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, as long as no contradictions arise. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present invention are not limited to these, and can be modified as appropriate within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0112] The composite cooling device of the present invention and its manufacturing method can be effectively used as a composite cooling device that has high reflectance from the visible light region to the infrared region, has high infrared emissivity at the atmospheric window, maintains good cooling function even when localized heating occurs, and is unlikely to reveal a specific color even when used under harsh conditions, and as a manufacturing method thereof. [Explanation of symbols]

[0113] B: Light reflective layer BA: Base material layer CP: Composite cooling device F: White filler H: Radiation surface HO:Protective layer IR: Infrared light J: Infrared radiation layer S: Connection layer

Claims

1. A complex cooling device comprising: an infrared emitting layer that emits infrared light from a emitting surface; and a light reflecting layer that is located on the infrared emitting layer on the opposite side to the side where the emitting surface is present, the light-reflecting layer has a thickness of 50 nm or more and 500 nm or less and is made of a metal containing 50 mass % or more and 100 mass % or less of copper, a base layer formed of a resin material between the infrared radiation layer and the light reflection layer, At least one of the infrared radiation layer and the base layer contains at least one of a white filler having an arithmetic mean particle size of 2 μm or less and pores having an arithmetic mean pore size of 0.01 μm or more and 2 μm or less.

2. The complex cooling device according to claim 1 , wherein the white filler has an arithmetic mean particle size of 0.2 μm or more and 1 μm or less.

3. 3. The complex cooling device according to claim 1, wherein the resin material forming the base layer includes at least one of a polyester resin, an acrylic resin, and a urethane resin.

4. 3. The composite cooling device according to claim 1, wherein the resin material forming the infrared radiation layer includes at least one of polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, and polyvinylidene fluoride.

5. 3. The complex cooling device according to claim 1, wherein a mass ratio of the white filler to the mass of the infrared radiation layer and the base layer containing the white filler is 0.1 mass % or more and 40 mass % or less.

6. In a configuration in which at least one of the infrared radiation layer and the base layer contains at least one of the white filler and the pores, 3. The complex cooling device according to claim 1, wherein the infrared radiation layer and the base material layer have an average reflectance of 70% or more in the visible light region having a wavelength of 400 nm to 800 nm.

7. a protective layer is provided on the side of the light reflecting layer opposite to the side on which the base layer is present, 3. The complex cooling device according to claim 1, wherein the protective layer contains an anticorrosive agent containing at least one of thiazole, imidazole, benzotriazole, and a chromate-based compound.

8. The composite cooling device according to claim 1 or 2, wherein the base layer contains a corrosion inhibitor containing benzotriazole.

9. 3. The composite cooling device according to claim 1, wherein at least one of a first connection layer serving as a connection layer connecting the infrared radiation layer and the base material layer and a second connection layer connecting the base material layer and the light-reflecting layer contains at least one of a white filler and hollow particles.

10. 3. The complex cooling device according to claim 1, wherein the light reflecting layer has an average reflectance of 80% or more in the infrared light region having a wavelength of 800 nm or more and 1200 nm or less.

11. A method for manufacturing the composite cooling device according to claim 1 or 2, the substrate layer is polyethylene terephthalate containing the white filler, The manufacturing method includes vapor-depositing the metal onto the base layer to form the light-reflecting layer.

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