Composite cooling device and manufacturing method thereof

Abstract

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 a good cooling function even when localized heating occurs, and is unlikely to show a specific color even in a severe usage environment, and a manufacturing method thereof. [Solution] The light-reflecting layer (B) has a thickness of 50 nm or more and 500 nm or less, and is made of a metal containing 50% by mass or more and 100% by mass or less of copper. A base material layer (BA) formed of a resin material is provided between the infrared-emitting layer (J) and the light-reflecting layer (B). At least one of the infrared-emitting 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 having an arithmetic mean pore diameter of 0.01 μm or more and 2 μm or less.

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 side of the infrared emitting layer opposite to the side on which 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 to its surroundings. By utilizing this phenomenon, for example, it is possible to create a composite 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 emitting layer that emits infrared light from a emitting surface and a light reflecting layer that is positioned on the side of the infrared emitting layer opposite to the side where the emitting surface exists (see, for example, Patent Document 1). Patent Document 1 shows that the light reflecting layer is made of silver or a silver alloy. On the other hand, Patent Document 2 discloses that an infrared emitting layer that emits infrared light from a radiation surface is composed of a polymer and a plurality of non-polymer particles mixed into the polymer particles, and that the light reflecting layer may contain copper as a metal. 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] JP 2018-165611 A [Patent Document 2] Special Publication No. 2019-515967 [Patent Document 3] JP 2018-169456 A 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 a problem that, under certain harsh environments, silver particles in the silver alloy may aggregate and take on a certain color.

[0006] In addition, 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, so it is difficult to make the metal layer thick enough and to ensure 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 exhibited.

[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 evaporated at a lower evaporation temperature than silver. However, copper has a low reflectance in the visible light range, and therefore cannot exhibit sufficient cooling performance when used as a light reflecting layer. Furthermore, copper has the property of having low reflectance, particularly in the visible light range. However, in the technology disclosed in Patent Document 2, when copper is used as the metal reflective layer, no consideration was given to a configuration for improving the low reflectance, particularly in the visible light range.

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

[0009] The present invention has been made in consideration 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 a 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] In order to achieve the above object, the composite cooling device comprises: A complex cooling device comprising an infrared emitting layer that emits infrared light from a emitting surface, and a light reflecting layer located on the infrared emitting layer on the opposite side to the side on which the emitting surface is present, The light reflecting layer has a thickness 100 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 a pore having an arithmetic mean pore size of 0.01 μm or more and 2 μm or less. fruit, when the white filler is contained in at least one of the infrared emitting layer and the base material layer, a mass ratio of the white filler to the mass of the infrared emitting layer and the base material layer containing the white filler is greater than 5 mass%, The combined thickness of the infrared radiation layer and the base layer is 20 mm or less, the resin material forming the infrared radiation layer includes at least one of polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, and polyvinylidene fluoride; The resin material forming the base layer is a resin material containing any one of an ester bond, an ether bond, and a benzene ring, and containing at least one of a polyester resin, an acrylic resin, and a urethane resin. It is at the point.

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

[0012] Furthermore, although copper alone has a high reflectance in the infrared light region, it has a low reflectance in the visible light region, and there is a concern that visible light may heat the object to be cooled. However, the inventors have discovered that by including at least one of white filler having an arithmetic mean particle diameter of 2 μm or less and pores having an arithmetic mean pore diameter 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 the light reflectance in the visible light region at a certain level or higher, as shown in the test results described later. Incidentally, according to the above-mentioned 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 that radiates infrared light. Therefore, a sufficient radiative cooling function can be exhibited without making the other of the infrared radiation layer or the base material layer unnecessarily thick. Furthermore, if the resin material forming the substrate layer is at least one of polyester resin, acrylic resin, and urethane resin, damage to the substrate is reduced when copper is vapor-deposited, and a uniform reflective layer can be formed, which is desirable for achieving a high and uniform reflectance over the entire surface. On the other hand, if PVC or the like is used for the substrate, outgassing occurs due to substrate damage during vapor deposition, which prevents the metal layer from being formed uniformly, and is therefore undesirable. Furthermore, since the resin material forming the infrared radiation layer contains at least one of polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, and polyvinylidene fluoride, infrared light can be appropriately radiated to the atmospheric window, thereby providing a good radiative cooling function. Furthermore, the mass ratio of the white filler to the volume of the infrared emitting layer and the base layer containing the white filler is greater than 5 mass %, and the combined thickness of the infrared emitting layer and the base layer is 20 mm or less.

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

[0014] As described above, a composite cooling device can be realized 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 exhibit a specific color even when used under harsh conditions.

[0015] Further features of the combined cooling system 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, such as 0.2 μm or more and 1 μm or less, the infrared radiation layer or base material layer containing the white filler therein can have a sufficiently high reflectance, particularly for visible light.

[0021] Further features of the combined cooling system include: a mass ratio of the white filler to the mass of the infrared radiation layer and the base layer containing the white filler is 、4 0 mass % or less.

[0022] As described above, the mass ratio of the white filler to the volume of the infrared radiation layer and the base layer containing the white filler is 、4 It is preferably 0 mass % or less. The mass ratio of the white filler is 、4 If the pigment concentration is more than 0 mass%, there are disadvantages in that if the pigment concentration is too high, the film-forming properties in R2R may be poor, flexibility may be lost, and the emissive layer may become easily torn after long-term use.

[0023] Further features of the combined cooling system 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 holes, The infrared radiation layer and the base layer have an average reflectance of 70% or more in the visible light region having a wavelength of 400 nm or more and 800 nm or less.

[0024] As described above, in a configuration in which at least one of the infrared radiation layer and the base material layer contains either a white filler or holes, the average reflectance of the infrared radiation layer and the base material 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 system 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 chromate-based compound.

[0026] Further features of the combined cooling system include: The base layer contains a corrosion inhibitor containing thiazole, imidazole, benzotriazole, and a chromate-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 chromate-based compound, which exhibits an anticorrosive function for copper or a copper alloy, it is possible to prevent oxidation of the light-reflecting layer for a long period of time and to maintain a high reflectance.

[0028] Further features of the combined cooling system include: 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 a hollow particle.

[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 in 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 system include: 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.

[0031] As described above, since the light-reflecting layer has an average reflectance of 80% or more in the infrared light range with a wavelength 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 the radiative cooling function.

[0032] The features of the manufacturing method for the composite cooling device explained so far are: the base layer is polyethylene terephthalate containing the white filler, The metal is vapor-deposited onto the base 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 description of the drawings]

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

[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 emits infrared light IR from an emitting surface H, and a light reflecting layer B that is located on the side of the infrared emitting layer J opposite to the side where the emitting surface H exists, and is formed in a film shape. In other words, the composite cooling device CP is configured as a radiative cooling film. To explain further, in the composite cooling device CP according to the embodiment, the light reflecting layer B has a thickness of 100 The infrared emitting layer (J) and the base material layer (BA) are made of a metal having a diameter of from 100 nm to 500 nm and containing 50% by mass to 100% by mass of copper, and are provided with a base material layer (BA) formed of a resin material between an infrared emitting layer (J) and a light reflecting layer (B), and at least one of the infrared emitting layer (J) and the base material layer (BA) is configured to contain 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 having a wavelength of 800 nm or more and 1200 nm or less.

[0036] In this embodiment, light L includes ultraviolet light, visible light, and infrared light, and when described in terms of the wavelength of light as electromagnetic waves, it includes 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 is particularly strong 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 on which 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, or 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. Although not shown, in the composite cooling device CP shown in Figures 1 to 3, only the base material layer BA may contain pores, or both the infrared radiation layer J and the base material layer BA may contain pores, or only the infrared radiation layer J may contain pores. As an example, as shown in FIG. 13, the infrared emitting layer J may not include white filler F and holes, and only the base layer BA may include white filler F and holes K.

[0039] However, from the viewpoint of favorable infrared radiation by the infrared emitting layer J, it is preferable that the infrared emitting layer J does not contain pores. By including pores in the infrared emitting layer J, it is possible to favorably prevent the adhesion of dirt to the radiation surface H of the infrared emitting layer J, which is often exposed to the outside. In addition, the volume ratio of the resin material in the infrared emitting layer J can be increased, and the thickness of the infrared emitting layer J can be reduced.

[0040] The connection layer S is made of at least one of adhesive, pressure sensitive adhesive, and glue. As a specific material of the connection layer S, an acrylic adhesive, a urethane adhesive, a silicone adhesive, and the like can be suitably used. Although not shown, the connection layer S includes at least one of a white filler F and hollow particles, so that the reflectance of light in the ultraviolet to visible region can be improved, and the thickness of the composite cooling device CP (particularly, the light reflecting layer B) can be reduced to obtain a desired reflectance. Here, the white filler and hollow particles can be suitably used with an arithmetic mean particle diameter of about 0.1 μm to 5 um, and the white filler can be suitably used with granulated TiO2, MgSO4, BaSO4, and TiBaO3. 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 chromate-based 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. In addition to reflecting the light L incident on the composite cooling device CP by the light reflecting layer B, when the infrared radiation layer J includes at least one of a white filler F and holes, the light L is reflected by the infrared radiation layer J, and when the base layer BA includes at least one of a white filler F and holes, 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 (for example, heat input by thermal conduction from the object to be cooled), by converting the heat input into infrared light IR by the infrared radiation layer J and radiating it, thereby cooling the object to be cooled.

[0044] In other words, the composite cooling device CP is configured to reflect light L irradiated to the composite cooling device CP and to radiate heat transferred to the composite cooling device CP (e.g., heat transfer 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 reflective 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 radiating layer J 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 directed toward 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 may 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 in which they have an absorption coefficient 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 relation A=1-exp(-αt) (hereafter referred to as the light absorptance relation). Here, t is the film thickness. In other words, by adjusting the film thickness of the infrared radiative layer J, a large thermal radiation can be obtained 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 the atmospheric window, that is, from 8 μm to 13 μm. In addition, to suppress the absorption of sunlight, it is advisable to use a material that has no or has 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 relational equation between the absorption coefficient and the 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 by 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 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 band from 8 μm to 13 μm, which is the atmospheric window, with the absorption coefficient being particularly large at 8.6 μm. In addition, regarding the solar wavelength band, there is no noticeable absorption coefficient in the wavelength range from 0.3 μm to 2.5 μm, where the energy intensity is high.

[0050] Resin materials having carbon-fluorine bonds (CF) include: These include polyvinyl fluoride (PVD) and polyvinylidene fluoride (PVDF). In the following, polyvinyl fluoride may be referred to as vinylyl fluoride resin, but the two are used to 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, due to the electron-withdrawing effect of chlorine, an absorption coefficient originating from the bending vibration of CH of the alkene contained in the main chain appears at a wavelength of around 10 μm.

[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] [Optical absorption considerations] Let us consider the light absorption in the ultraviolet-visible region of resin materials with the bonds and functional groups described above, that is, sunlight absorption. The origin of the absorption of ultraviolet to visible light is the transition of electrons that contribute to the bonds. Absorption in this wavelength range can be understood by calculating the bond energy. First, let us 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 structure 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 absorb light of these wavelengths.

[0055] Since the solar spectrum only contains wavelengths longer than 0.300μm, 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 0.400μm, visible light as wavelengths from 0.400μm to 0.800μm, near-infrared rays as wavelengths from 0.800μm to 3μm, mid-infrared rays as wavelengths from 3μm to 8μm, and far-infrared rays as wavelengths longer than 8μm.

[0056] Regarding the carbon-chlorine bond (C-Cl), the bond energy between the carbon and chlorine in an alkene is 3.28 eV, and the wavelength is 0.378 μm, so it absorbs a lot of ultraviolet light in sunlight, but has almost no absorption in the visible range. FIG. 5 shows the absorption spectrum of a 100 μm thick polyvinyl chloride resin in the ultraviolet to visible range, and light absorption increases at wavelengths shorter than 0.38 μm. FIG. 5 shows the absorptance spectrum of a 100 μm thick vinylidene chloride resin in the ultraviolet to visible range, and a slight increase in the absorptance spectrum is observed on the shorter wavelength side than 0.4 μm.

[0057] Resins with ester bonds (R-COO-R), ether bonds (COC 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 absorption spectrum from ultraviolet to visible light of a 5 mm-thick methyl methacrylate resin is shown in Figure 5. The methyl methacrylate resin shown 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.

[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 the absorptance increases sharply at a wavelength of 0.315 μm. Note that with ethylene terephthalate resin, as the thickness is increased, the absorptance due to the absorption edge derived from the C-C bond increases slightly longer than the wavelength of 0.315 μm, and the absorptance of ultraviolet light increases in the same way as with methyl methacrylate resin.

[0060] As long as the infrared radiation layer J uses a resin material having the above-mentioned emissivity (light emissivity) and light absorptivity characteristics, it may be a single layer film of one type of resin material, a multilayer film of multiple types of resin materials, a single layer film of a resin material in which multiple types of resin materials are blended, or a multilayer film of a resin material in which multiple types of resin materials are blended. The blends 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 polyvinyl 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 resin with carbon-chlorine bonds, and Figure 7 shows the emissivity of polyvinylidene chloride resin (PVDC) at the atmospheric window. For carbon-chlorine bonds, 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 the case of polyvinyl chloride resin, the absorption coefficient due to the bending vibration of CH of the alkene contained in the main chain appears at a wavelength of around 10 μm due to the electron-withdrawing effect of chlorine. The same is true for vinylidene chloride resin. Due to these effects, the wavelength average of the emissivity of a 10 μm thick film is 43% at wavelengths from 8 μm to 13 μm, which falls within the regulation of a 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] FIG. 8 shows the emissivity of ethylene terephthalate resin at the atmospheric window as a representative example of a resin having an ester bond or a benzene ring. Ester bonds have an absorption coefficient in the wavelength range from 7.8 μm to 9.9 μm. Furthermore, the carbon-oxygen bonds contained in ester bonds have a strong absorption coefficient in the wavelength range from 8 μm to 10 μm. When a benzene ring is introduced into the side chain of a hydrocarbon resin, absorption appears in a wide 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. Due to these effects, the wavelength average of the emissivity of a 10 μm thick film is 71% at wavelengths from 8 μm to 13 μm, which falls within the regulation of a 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] Thermal radiation from 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 polyvinyl 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 polyvinyl chloride resin, thermal radiation in the atmospheric window occurs within a depth of about 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 shown in Fig. 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 air window region. In other words, in the case of ethylene terephthalate resin, thermal radiation in the air window occurs at a depth of about 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 composite cooling device is insulated by the resin material that does not contribute to thermal radiation. Ideally, it is considered that the infrared emitting layer J and the base material layer BA are made of a resin that does not absorb any sunlight, and that 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 calculations are made taking this thermal conductivity into consideration, if the thickness of the infrared emitting layer J exceeds 20 mm, the temperature of the cooling surface (the surface of the light reflecting layer B opposite the side where the infrared emitting layer J is present) will rise.

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

[0067] Figure 9 is a plot of 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 south in midsummer in western Japan. The sunlight is AM1.5 and 1000W / m 2The outside temperature is 30°C, and the radiant energy varies depending on the temperature, but is 100 W 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 5 W / m 2 / K.

[0068] [Light absorption of hydrocarbon resins] When the resin material forming the infrared radiation layer J or the base material 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, the absorption due to the reference tones of the transitions to the first excited state 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, the absorption due to the reference 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, the overtones of the transitions to the second excited state of CH2 and CH appear at around 1.24 μm. The reference tones of the bending and stretching of the CH 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, a large optical absorption occurs at a wavelength of around 1.9 μm. According to the above-mentioned relational expression of light absorptance, the light absorptance caused by these factors becomes small and inconspicuous when the film thickness of the resin material is thin, but becomes large when the film thickness is thick.

[0071] [Light absorption of blended 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 according to the ratio 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 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 a hydrocarbon, and alternating copolymers, random copolymers, block copolymers and graft copolymers of a fluoromonomer and a hydrocarbon monomer.

[0073] Depending on the molecular weight and ratio of the substituted hydrocarbon side chains, optical absorption in the near infrared region caused by CH, CH2, CH3, etc. appears. When the monomers introduced as side chains or copolymers are low molecular weight, or when the density of the monomers introduced is low, optical absorption in the near infrared region caused by 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 the minimum necessary. The thicker the infrared radiation layer J is, the greater the thermal radiation of the atmospheric window becomes, and above a certain thickness, the thermal radiation energy at the atmospheric window becomes saturated.

[0075] The thickness at which the film saturates depends on the resin material, but in the case of fluororesin, 300 μm is generally sufficient for saturation. Therefore, from the perspective of thermal conductivity, it is preferable to keep the film thickness at 300 μm or less rather than 500 μm. Furthermore, although thermal radiation is not saturated, 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 at around 100 μm or less.

[0076] The absorption coefficients due to carbon-silicon bonds, carbon-chlorine bonds, carbon-oxygen bonds, ester bonds, and ether bonds are greater than the absorption coefficient due to C-F bonds. Naturally, from the viewpoint 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 to increase thermal conductivity. In the case of resins containing carbon-chlorine bonds, even a thickness of 100 μm is saturated, and even a thickness of 50 μm provides sufficient heat radiation in the atmospheric window region. The thinner the resin material, the higher the thermal conductivity and the more effectively the temperature of the object to be cooled can be lowered, so in the case of resins containing carbon-chlorine bonds, a thickness of 50 μm or less reduces the insulation 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 caused by resins that contain carbon-chlorine bonds. By making the material thinner, it is possible to reduce the amount of sunlight absorbed by these compounds, which increases 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 described later, in the composite cooling device CP according to the embodiment, a certain degree of heat radiation can be expected by using a resin as the base layer BA. 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 the use of a metal mainly made of silver (silver or silver alloy) by using a metal mainly made of copper as the light reflecting layer B. In addition, it has been confirmed by a test described later that the use of a metal mainly made of copper can reduce the entrapment of the resin material due to heat, even when a relatively thick light reflecting layer B is formed by vapor deposition on the infrared radiation layer J made of a resin material. More specifically, the light reflecting layer B is made of a metal (copper or a 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 described 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 fulfill the light-reflecting function of the complex 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 Material 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 a polyester-based resin, an acrylic-based resin, and a urethane-based 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 size of 0.01 μm or more and 2 μm or less in place of the second white filler F2. The base layer BA may 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 holes described above. As shown in the composite cooling device CP shown in FIG. 3, a configuration in which the infrared radiation layer J contains at least one of the first white filler F1 as the white filler F and holes may be adopted. 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 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 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 (or / and holes), the following mass ratio is preferable.

[0086] The mass ratio of the first white filler F1 in the infrared emitting layer J is More than 5% by mass It is preferably 40% by mass or less.

[0087] The infrared emitting layer J may contain the above-mentioned holes instead of the above-mentioned first white filler F1. Also, the infrared emitting layer J may contain the above-mentioned holes in addition to the first white filler F1.

[0088] The mass ratio of the white filler F to the volume of the infrared radiation layer J and the base layer BA containing the white filler F is More than 5% by mass It is preferably 40% by mass or less.

[0089] By adopting the above configuration, the composite cooling device CP according to this embodiment realizes a configuration with an average reflectance of 70% or more in the visible light range of wavelengths from 400 nm to 800 nm by the infrared radiation layer J and the 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 realizes 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 of 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 emitting layer J and the base material layer BA was selected in this manner is that it has a very high emissivity at wavelengths of 8 to 13 μm and is also excellent in long-term weather resistance.

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

[0093] From the viewpoint of improving the infrared emissivity and, in particular, 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] It is preferable that 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 or more and 100% by mass or less of copper on the base layer BA.

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

[0097] [Experimental Results] For the above-described composite cooling examples and comparative examples, various tests were conducted on the visible light reflectance at wavelengths of 400 nm to 800 nm, the infrared light reflectance at wavelengths of 800 nm to 1200 nm, the infrared emissivity, planar thermal conductivity, metal layer imparting properties, and coloring 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 FIG. 3, Examples 5, 6, and 7 relate to the stacking configuration shown in FIG. 2, and Example 2 relates to the stacking configuration shown in FIG. 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 composite cooling device are as shown in Tables 3 and 4. For convenience of explanation, the white filler is omitted from 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 with a UV-Visible spectrometer UV-2600 (Shimadzu Corporation). A reflectance of 80% or more was defined as satisfying the condition (high reflectance in the wavelength range of 400 to 800 nm).

[0099] The infrared reflectance from 800 to 1200 nm was evaluated using the arithmetic mean of the reflectance from 800 to 1200 nm measured with a UV-Visible spectrometer UV-2600 (Shimadzu Corporation). A material with an infrared reflectance of 80% or more was defined as satisfying the condition (high reflectance from 800 to 1200 nm).

[0100] The infrared emissivity was evaluated using the arithmetic mean of the emissivity at wavelengths from 8 μm to 13 μm measured using an FT-IR IR Tracker-100 (manufactured by Shimadzu Corporation). Products with an emissivity of 90% or more were defined as meeting the conditions.

[0101] The planar thermal conductivity was measured using the laser flash method defined in JIS R1611. The value in Example 1 was defined as 1.0, and values ​​equal to or higher 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 was measured before and after the test. 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 by 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 at wavelengths of 400 nm to 800 nm, infrared light reflectance at wavelengths of 800 nm to 1200 nm, infrared emissivity, planar thermal conductivity, metal layer imparting properties, and coloration due to condensation.

[0108] On the other hand, in Comparative Examples 3 and 5, the main reason for not satisfying the condition for visible light reflectance is thought to be that the base layer BA does not contain a white filler, in Comparative Example 7, the main reason for not satisfying the condition for infrared reflectance is thought to be that the light-reflecting layer B is not provided, in Comparative Examples 3, 4, and 7, the main reason for not satisfying the condition for infrared emissivity is thought to be that the infrared radiation layer J is not provided, in Comparative Examples 5 and 7, the main reason for not satisfying the condition for planar thermal conductivity is thought to be that the thickness of the copper alloy constituting the light-reflecting layer B is thin, in Comparative Example 6, the main reason for not satisfying the condition for metal impartation is thought to be that 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 main reason for not satisfying the condition for coloration due to condensation (coloration occurred due to condensation) is thought to be that the metal material constituting the light-reflecting layer B contains silver. In addition, in Comparative Example 5, the thickness of the light reflecting layer is as thin as 20 nm, so that the reflectance is not sufficient.

[0109] In other words, from the viewpoint of suppressing coloration due to metal aggregation, 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, provided that no contradiction arises. Furthermore, the embodiments disclosed in this specification are merely examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present invention. [Industrial Applicability]

[0112] The composite cooling device and its manufacturing method of the present invention 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 in harsh conditions, and 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 located on the infrared emitting layer on the opposite side to the side on which the emitting surface is present, the light reflecting layer has a thickness of 100 nm or more and 500 nm or less, and is made of a metal containing 50% by mass or more and 100% by 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 a pore having an arithmetic mean pore size of 0.01 μm or more and 2 μm or less, when the white filler is contained in at least one of the infrared emitting layer and the base material layer, a mass ratio of the white filler to the mass of the infrared emitting layer and the base material layer containing the white filler is greater than 5 mass%, The combined thickness of the infrared radiation layer and the base layer is 20 mm or less, the resin material forming the infrared radiation layer includes at least one of polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, and polyvinylidene fluoride; The resin material forming the base layer is a resin material containing any one of an ester bond, an ether bond, and a benzene ring, and also contains at least one of a polyester resin, an acrylic resin, and a urethane resin.

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 a mass ratio of the white filler to the mass of the infrared radiation layer and the base layer containing the white filler is 40 mass % or less.

4. 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 holes, 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 or more and 800 nm or more.

5. 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 of claim 1 or 2, wherein the protective layer includes an anticorrosive agent including at least one of thiazole, imidazole, benzotriazole, and a chromate-based compound.

6. The composite cooling device of claim 1 or 2, wherein the base layer includes a corrosion inhibitor including benzotriazole.

7. 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 a hollow particle.

8. 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.

9. A method for manufacturing the composite cooling device according to claim 1 or 2, comprising the steps of: the base layer is polyethylene terephthalate containing the white filler, The manufacturing method includes depositing the metal on the base layer to form the light reflecting layer.

Images