Light-absorbing heat-shielding film, light-absorbing heat-shielding member, and articles, and methods for manufacturing the same.

Abstract

The present invention is characterized by being provided with a metal layer having rugged-shaped objects, and is characterized in that the rugged-shaped objects each have a second rugged structure formed on a first rugged structure.

Description

Technical Field

[0001] The present invention relates to an absorptive heat-insulating film, an absorptive heat-insulating member, an article, and methods for manufacturing them.

Background Art

[0002] In recent years, the use of heat-insulating materials for suppressing temperature rise has been expanding in interior and exterior components of optical devices, space devices, and transportation devices. In addition, materials that are heat-insulating and also have light-absorbing properties can reduce noise caused by stray light when used in the lens barrel of an infrared camera or in a diaphragm film, and are difficult to increase in temperature and have high dimensional stability. Therefore, materials having both light-absorbing and heat-insulating properties are required. Conventionally, as a light-absorbing material, a light-absorbing material with black electroless nickel plating is known (for example, Non-Patent Document 1). This makes the surface black by forming fine irregularities by oxidizing the nickel plating on the object surface and serves as a light-absorbing material. Also, a technique for producing a resin having a fine structure on the surface by injection molding using a mold having fine irregularities on the metal surface has been shown (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the black material shown in Non-Patent Document 1 has the problem of exhibiting high radiation even in the far-infrared region and not showing excellent heat shielding properties. Furthermore, the invention described in Patent Document 1 involves injection molding of resin using a mold, and it is not possible to mold a metal film in a highly versatile form, making it difficult to apply to various products as a light-absorbing heat shielding member, thus posing a challenge to its practicality.

[0006] Furthermore, heat-shielding materials typically have the problem of reflecting ambient light sources depending on the shooting angle of the thermal imaging camera, making it difficult to see the heat-shielding object (due to significant reflection (glare) of light emitted from the light source).

[0007] This invention has been made in view of the above problems, and aims to provide a light-absorbing and heat-shielding member that absorbs visible light and near-infrared rays, which are normally incompatible, has the characteristic of absorbing far-infrared rays with low radiation, and suppresses reflection of ambient light sources. [Means for solving the problem]

[0008] Embodiments of the present invention are A light-absorbing and heat-shielding film comprising a metal layer, wherein the metal layer includes a base portion in which the metal layer is continuous in the extending direction of the light-absorbing and heat-shielding film, and an uneven-shaped portion provided on the base portion, wherein the uneven-shaped portion has a first uneven structure including a plurality of protrusions, and a second uneven structure including a plurality of protrusions provided on each of the plurality of protrusions, wherein the base portion extends beneath the plurality of protrusions included in the first uneven structure, and the main component of the metal material of the base portion, the first uneven structure, and the second uneven structure is the same. .

[0009] Embodiments of the present invention are light-absorbing and heat-shielding films comprising a metal layer, wherein the metal layer is concave convex shape department The uneven surface includes a first uneven structure comprising a plurality of protrusions, and a second uneven structure comprising a plurality of protrusions, provided on each of the plurality of protrusions. ,before The main components of the metal material of the first uneven structure and the second uneven structure are the same. and comprising metal oxides attached to the surface of the uneven shape portion It is characterized by the following.

[0010] Embodiments of the present invention relate to a method for manufacturing a light-absorbing heat-shielding film. teeth The method includes the steps of preparing a mold having an uneven shape and forming a metal layer on which the uneven shape is transferred, wherein the mold has an uneven structure including a plurality of recesses, and the uneven shape includes a plurality of recesses provided on the surface of each of the plurality of recesses included in the uneven structure.

[0011] An embodiment according to the present invention, the manufacturing method of the light absorption heat insulation film includes a step of preparing a substrate having an uneven structure, The process includes the steps of forming a metal layer on which the uneven shape is transferred onto the mold, and adhering a substrate to the side of the metal layer opposite to the side on which the uneven shape is transferred, wherein the mold has an uneven structure including a plurality of recesses, and the uneven shape is provided on the surface of each of the plurality of recesses included in the uneven structure, and is characterized by including the following.

Effect of the Invention

[0012] According to the present invention, a light absorption heat insulation film excellent in light absorption heat insulation characteristics can be provided.

Brief Description of the Drawings

[0013] [Figure 1A] It is a schematic diagram showing an embodiment of the light absorption heat insulation film of the present invention. [Figure 1B] It is a schematic diagram showing an embodiment of the light absorption heat insulation film of the present invention. [Figure 1C] It is a schematic diagram showing an embodiment of the light absorption heat insulation film of the present invention. [Figure 2A] It is a schematic diagram showing an embodiment of the light absorption heat insulation member of the present invention. [Figure 2B] It is a schematic diagram showing an embodiment of the light absorption heat insulation member of the present invention. [Figure 3A] It is a process diagram showing an embodiment of the manufacturing method of the light absorption heat insulation member of the present invention. [Figure 3B] It is a process diagram showing an embodiment of the manufacturing method of the light absorption heat insulation member of the present invention. [Figure 3C] It is a process diagram showing an embodiment of the manufacturing method of the light absorption heat insulation member of the present invention. [Figure 3D] It is a process diagram showing an embodiment of the manufacturing method of the light absorption heat insulation member of the present invention. [Figure 3E] It is a process diagram showing an embodiment of the manufacturing method of the light absorption heat insulation member of the present invention. [Figure 3F] It is a process diagram showing an embodiment of the manufacturing method of the light absorption heat insulation member of the present invention. [Figure 3G] It is a process diagram showing an embodiment of the manufacturing method of the light absorption heat insulation member of the present invention. [Figure 3H] It is a process diagram showing an embodiment of the manufacturing method of the light absorption heat insulation member of the present invention. [Figure 4]This is an electron microscope image of a cross-section of the light-absorbing heat-shielding member obtained in Example 1. [Figure 5] This is an electron microscope image of a cross-section of the light-absorbing heat-shielding member obtained in Example 1. [Figure 6] These are the measurement results of the reflectance spectra in the visible light region of the light-absorbing members obtained in Example 1 and Comparative Example 1. [Figure 7] These are the measurement results of the reflectance spectra in the infrared region of the light-absorbing members obtained in Example 1 and Comparative Example 1. [Modes for carrying out the invention]

[0014] The embodiments of the present invention will be described in detail below.

[0015] The light-absorbing heat-shielding film according to this embodiment comprises a fine uneven surface, the fine uneven surface having a layered structure, the layered structure including a first uneven surface (first structure) and a second uneven surface (second structure). Furthermore, the light-absorbing heat-shielding film according to this embodiment comprises a metal layer, the metal layer comprising a base, a first uneven surface (first structure), and a second uneven surface (second structure). The first uneven surface (first structure) is formed on the base, and the second uneven surface (second structure) is formed on the first uneven surface (first structure). In other words, the fine uneven surface of the light-absorbing heat-shielding film is a metal layer. In this specification, the fine uneven surface may be simply referred to as an uneven surface.

[0016] Highly conductive metals such as aluminum and nickel emit little far-infrared radiation and have heat-shielding properties, but they do not exhibit light absorption. On the other hand, micro-rough surfaces with subwavelength structures smaller than the wavelength of visible light are known to have an anti-reflective effect, and by continuously changing the spatial occupancy rate of the structural parts, they are known to exhibit excellent wavelength band characteristics and incident angle characteristics. Therefore, when a metal surface is made micro-rough, reflection from the metal surface is suppressed over a wide wavelength range of visible light, the reflectivity across the entire visible light range decreases, it appears black, and light absorption is exhibited. Thus, it is thought that metal components with a micro-rough surface structure can possess both light absorption and heat-shielding properties. However, the light-absorbing material shown in Non-Patent Literature 1 has a micro-rough surface obtained by oxidizing a nickel surface, but it emits a large amount of radiation (low reflectivity) even in the far-infrared region and does not exhibit heat-shielding properties. Furthermore, in practical use, heat-shielding materials typically have the problem of reflecting ambient light sources depending on the shooting angle of the thermal imaging camera, making it difficult to see the heat-shielding subject (due to significant reflection (glare) of light emitted from the light source).

[0017] Based on this, the inventors discovered that, in addition to the heat-shielding properties of the metal itself that forms the light-absorbing heat-shielding film, forming a hierarchical microstructure in the fine uneven shape of the metal surface allows for the expression of light-absorbing heat-shielding properties while suppressing reflection of ambient light sources, thus completing this embodiment.

[0018] The aforementioned hierarchical microstructure is composed of at least two types of structures with different structural sizes, for example, a structure that combines a first structure having a micron-order structural size and a second structure having a submicron-order structural size. The first structure has the effect of suppressing reflections of surrounding light sources, while the second structure reduces reflectivity across the entire visible light region, appears black, and exhibits light absorption.

[0019] The above-mentioned light absorption, heat shielding, and effect of suppressing light source reflection can be broadly controlled by appropriately combining the size of the surface microstructure of the light-absorbing and heat-shielding film and the material used for the film.

[0020] <Light absorption heat shield film> The light-absorbing heat-shielding film of this embodiment will be described with reference to Figure 1. As shown in Figure 1A, one embodiment of the light-absorbing heat-shielding film of the present invention is a light-absorbing heat-shielding film 10 comprising a metal layer 1 having a fine uneven surface portion 2 (uneven surface portion) on its surface. The light-absorbing heat-shielding film 10 has a base portion 11 below the fine uneven surface portion 2, and this base portion 11 is part of the metal layer 1. As the material of the base portion 11 in the metal layer 1, a metal with high conductivity is preferred. Examples of metals with high conductivity include silver, copper, gold, aluminum, magnesium, tungsten, cobalt, zinc, nickel, and chromium, with nickel, zinc, and chromium being preferred, and nickel being particularly preferred. The fine uneven surface portion 2 provided on the surface of the metal layer 1 is also preferably made of the above-mentioned metal with high conductivity, and more preferably made of the same metal as the base portion 11 of the metal layer 1.

[0021] Furthermore, a transparent metal oxide may be attached to the surface of the finely uneven shaped portion 2. In other words, the light-absorbing heat-shielding film 10 may contain a transparent metal oxide on the surface of the finely uneven shaped object (finely uneven shaped portion 2) which is the metal layer 1. The metal component of the metal oxide attached to the surface of the finely uneven shaped portion 2 may differ from the metal component of the metal layer 1. That is, for example, if the material of the metal layer 1 is nickel, the metal oxide attached to the surface of the finely uneven shaped portion 2 may be an oxide of a metal other than nickel. Therefore, the metal oxide attached to the surface of the finely uneven shaped portion 2 can be distinguished from a metal oxide that has the same metal component as the metal layer 1 and is formed by the natural oxidation of the metal layer 1. The attached metal oxide preferably has aluminum oxide as its main component, and may be a crystal with aluminum oxide as its main component. The crystal with aluminum oxide as its main component is formed from a crystal with aluminum oxide or hydroxide or hydrate thereof as its main component, and a particularly preferred crystal is boehmite. Here, the crystal mainly composed of aluminum oxide may be a crystal consisting solely of aluminum oxide, or it may be a crystal containing trace amounts of zirconium, silicon, titanium, zinc, etc.

[0022] The metal layer 1 includes a base portion 11 and a fine uneven surface portion 2 provided on the base portion 11. The base portion 11 is a continuous portion of the metal layer 1 in the extending direction of the light-absorbing heat-shielding film 10 (lateral direction in Figure 1), while the fine uneven surface portion 2 is a discontinuous portion of the metal layer 1 in the extending direction of the light-absorbing heat-shielding film 10 (lateral direction in Figure 1). In Figure 1, the boundary 12 between the base portion 11 and the fine uneven surface portion 2 is shown by a dashed line.

[0023] The micro-uneven surface portion 2 is a part of the metal layer 1 having a fine uneven surface, and the micro-uneven surface portion 2 has a layered structure. That is, the micro-uneven surface portion 2 has a first uneven structure 21 and a second uneven structure 22. An object having the micro-uneven surface portion 2 is a micro-uneven object, and since the micro-uneven surface portion 2 is part or all of the micro-uneven object, the micro-uneven surface portion 2 can also be referred to as the micro-uneven object.

[0024] The first uneven structure 21 includes a plurality of protrusions (for example, protrusions 211 and 212). The first uneven structure 21 also includes a plurality of recesses (for example, a recess 210 between protrusions 211 and 212). The protrusions 221 and 212 of the first uneven structure 21 are part of the metal layer 1, and the recesses 210 of the first uneven structure 21 are spaces where there is no metal layer 1 and a substance other than the metal layer 1 may exist.

[0025] The second uneven structure 22 includes a plurality of protrusions (for example, protrusions 221 and 222). The second uneven structure 22 also includes a plurality of recesses (for example, a recess 220 between protrusions 221 and 222). The protrusions 221 and 212 of the second uneven structure 22 are part of the metal layer 1, while the recesses 220 of the second uneven structure 21 are spaces where there is no metal layer 1 and a substance other than the metal layer 1 may exist.

[0026] The second uneven structure 22 is formed on the first uneven structure 21. In other words, the second uneven structure 22 is provided on each of the multiple protrusions (for example, protrusions 211 and 212) included in the first uneven structure 21. It is preferable that the main components of the metal material of the first uneven structure 21 and the second uneven structure 22 are the same.

[0027] The metal layer 1, which is an uneven surface in the light-absorbing heat-shielding film 10, has a base portion 11 made of a metal material having the same main component as the first uneven surface 21 and the second uneven surface 22, located beneath the first uneven surface structure 21. The base portion 11 extends beneath a plurality of protrusions (e.g., protrusions 211 and 212) included in the first uneven surface structure 21. In contrast, the fine uneven surface portion 2 is discontinuous in the metal layer 1 due to the recesses (e.g., recess 210) of the first uneven surface structure 21.

[0028] Furthermore, it is preferable that the main components of the metal material of the base 11, the first uneven structure 21, and the second uneven structure 21 are the same. By constructing the base 11, the first uneven structure 21, and the second uneven structure 21 from a common metal material (i.e., a single-layer metal layer 1), superior light absorption and heat shielding characteristics can be achieved compared to when they are constructed from different metal materials (i.e., multiple layers of metal).

[0029] Furthermore, it is preferable that the average roughness Ra1 of the first uneven structure 21 is 0.1 μm or more and 5 μm or less, and the average roughness Ra2 of the second uneven structure 22 is 1 nm or more and 50 nm or less.

[0030] Here, the average roughness of the finely uneven surface 2, or the average roughness of the finely uneven surface 2 to which transparent metal oxide is attached, refers to the arithmetic mean roughness as defined in "Definition and indication of surface roughness" of JIS-B-061. When a reference length is extracted from the roughness curve in the direction of the mean line, and the X-axis is taken in the direction of the mean line of the extracted portion, and the Y-axis is taken in the direction of the vertical scaling, the roughness curve is expressed as y=f(χ), and it can be calculated using the following equation (1).

[0031]

number

[0032] In equation (1), Ra is the average roughness (nm), L is the reference length, F(X,Y) is the height at the measurement point (X,Y) where the X coordinate is X and the Y coordinate is Y, X L ~X R This represents the range of the X coordinate of the measurement line.

[0033] Furthermore, in the light-absorbing heat-shielding film 10 according to this embodiment, it is preferable that the maximum height Rz1 of the first uneven structure 21 on the surface of the metal layer 1 is 1 μm or more and 10 μm or less, and the maximum height Rz2 of the second uneven structure 22 is 100 nm or more and 800 nm or less.

[0034] Here, the maximum height of the finely uneven surface area 2, or the maximum height of the finely uneven surface area 2 to which transparent metal oxide is attached, refers to the maximum height specified in "Definition and Indication of Surface Roughness" of JIS-B-061. This is calculated by extracting a reference length from the roughness curve in the direction of its average line, and measuring the distance between the peak line and the trough line of the extracted portion in the direction of the vertical magnification of the roughness curve. This trough line may correspond to the boundary 12 between the base 11 and the finely uneven surface area 2, which is shown as a dashed line in Figure 1.

[0035] The average roughness and maximum height of the fine uneven surface portion 2 can be determined by observing the cross-section of the light-absorbing heat-shielding film 10 of this embodiment with a scanning electron microscope or the like.

[0036] In another embodiment of the light-absorbing heat-shielding film of the present invention, as shown in Figure 1B, it may include a transparent fine metal oxide 3 that is in close contact with the fine uneven surface 2. In this specification, the fine metal oxide 3 may be simply referred to as a metal oxide. The fine metal oxide 3 is provided between a plurality of protrusions (for example, protrusions 221 and 222) included in the second uneven structure 21. That is, the fine metal oxide 3 fills the recess 220 between the protrusions 221 and 222.

[0037] Furthermore, in another embodiment of the light-absorbing heat-shielding film of the present invention, as shown in Figure 1C, a transparent metal oxide layer 4 may be further provided to cover the surface of the fine metal oxide 3 that is not in contact with the fine uneven surface portion 2. The metal oxide layer 4 covers the fine uneven surface portion 2, and the fine metal oxide 3 is provided between the metal oxide layer 4 and the metal layer 1.

[0038] Here, "closely adhering" means that the metal oxide fills the space (recess) surrounded by the fine uneven shape portion 2 and reaches the metal layer 1. In this specification, the metal oxide layer 4 may sometimes be simply referred to as the metal oxide.

[0039] The material of the fine metal oxide 3 is not particularly limited, but it is preferably mainly composed of aluminum oxide, and more preferably contains plate-like crystals mainly composed of aluminum oxide (hereinafter referred to as plate-like crystals). The plate-like crystals mainly composed of aluminum oxide are formed from crystals mainly composed of aluminum oxide or hydroxide or hydrates thereof, and a particularly preferred crystal is boehmite. Here, the plate-like crystals mainly composed of aluminum oxide may be plate-like crystals consisting only of aluminum oxide, or they may be plate-like crystals containing trace amounts of zirconium, silicon, titanium, zinc, etc. in addition to the plate-like crystals of aluminum oxide.

[0040] The presence of the fine metal oxide 3 protects the finely uneven surface 2. Furthermore, when the fine metal oxide 3 is a plate-like structure of plate-like crystals mainly composed of aluminum oxide, it is preferable that the plate-like crystals mainly composed of aluminum oxide are arranged perpendicular to the plane direction of the metal layer 1, and that their spatial occupancy rate changes continuously.

[0041] The material of the metal oxide layer 4 is not particularly limited, but it is preferable that it contains an amorphous gel of aluminum oxide. The metal oxide layer 4 increases the surface hardness of the light-absorbing heat-shielding film 10 of this embodiment, while decreasing its light absorption. Therefore, the thickness of the metal oxide layer 4 should be appropriately determined to satisfy the required hardness and light absorption.

[0042] Aluminum, silicon, and other elements in the fine uneven surface area 2, the fine metal oxide 3, and the metal oxide layer 4 can be detected by surface measurements using a scanning electron microscope (SEM) or transmission electron microscope (TEM). They can also be detected by energy-dispersive X-ray analysis (EDX) or X-ray electron spectroscopy (XPS) during cross-sectional observation. Similarly, metal elements such as silver, copper, gold, aluminum, magnesium, tungsten, cobalt, zinc, nickel, and chromium in the metal layer 1 can also be detected by surface measurements using a scanning electron microscope (SEM) or transmission electron microscope (TEM). They can also be detected by energy-dispersive X-ray analysis (EDX) or X-ray electron spectroscopy (XPS) during cross-sectional observation. When the fine uneven surface area 2, the fine metal oxide 3, or the metal oxide layer 4 are provided, the proportion of metal oxides such as aluminum decreases relatively from the surface (metal oxide layer 4) towards the interior (metal layer 1) in a direction perpendicular to the surface direction of the metal layer 1. Conversely, the relative proportion of metal elements constituting the metal layer 1 and the fine uneven surface area 2 increases from the surface (metal oxide layer 4) towards the interior (metal layer 1), and ultimately only metal elements are detected.

[0043] <Light-absorbing and heat-shielding material> As shown in Figure 2A, an embodiment of the light-absorbing heat-shielding member of the present invention is a light-absorbing heat-shielding member 100 in which a base material 5 is provided on the side of the metal layer 1 of the light-absorbing heat-shielding film 10 of this embodiment that is opposite to the fine uneven shape portion 2. The light-absorbing heat-shielding member 100 comprises a base material 5 and a light-absorbing heat-shielding film 10 provided on the base material 5. The shape of the base material 5 can be any shape that can be made according to the purpose of use, for example it may be a molded product, and examples include flat plate shape, film shape, sheet shape, etc., but is not limited thereto. Examples of materials for the base material 5 include metal, glass, ceramics, wood, paper, resin, etc., but is not limited thereto. Examples of resins include thermoplastic resins such as polyester, triacetylcellulose, cellulose acetate, polyethylene terephthalate, polypropylene, polystyrene, polycarbonate, and polymethyl methacrylate. Alternatively, ABS resin, polyphenylene oxide, polyurethane, polyethylene, and polyvinyl chloride can also be listed as thermoplastic resins. Furthermore, thermosetting resins such as unsaturated polyester resins, phenolic resins, cross-linked polyurethanes, cross-linked acrylic resins, and cross-linked saturated polyester resins are also mentioned.

[0044] As shown in Figure 2B, in another embodiment of the present invention, the light-absorbing heat-shielding film 10 and the substrate 5 may be bonded together by an adhesive layer 6. The adhesive layer 6 of the light-absorbing heat-shielding member 100 can be any layer that can bond the light-absorbing heat-shielding film and the substrate 5, but examples include a layer made of a cured adhesive resin (e.g., epoxy resin), double-sided tape, etc.

[0045] Although Figures 2A and 2B show a light-absorbing heat-shielding member 100 equipped with the light-absorbing heat-shielding film 10 shown in Figure 1C, the light-absorbing heat-shielding member 100 equipped with the light-absorbing heat-shielding film 10 shown in Figure 1C may be used instead of the light-absorbing heat-shielding film 10 shown in Figure 1C, as shown in Figure 1A or Figure 1B.

[0046] <Method for manufacturing light-absorbing heat-shielding film and light-absorbing heat-shielding member> The manufacturing methods for the light-absorbing heat-shielding film 10 and the light-absorbing heat-shielding member 100 of this embodiment will be described below with reference to Figure 3.

[0047] The manufacturing method of this embodiment includes a step of preparing a mold 9 having a fine uneven shape 92, as shown in Figure 3B. Since the fine uneven shape 92 is included in the uneven shape 90, this step can also be called a step of preparing a mold 9 having the uneven shape 90.

[0048] Type 9 has a recessed structure 91. The recessed shape formed by the recessed structure 91 is encompassed by the recessed shape 90. The recessed structure 91 includes a plurality of recesses (e.g., recesses 911, 912). A plurality of protrusions (e.g., protrusions 910) are provided between the plurality of recesses (e.g., recesses 911, 912) of the recessed structure 91.

[0049] The fine uneven surface shape 92 includes a plurality of recesses (e.g., recesses 921, 922). A plurality of protrusions (e.g., protrusions 920) are provided between the plurality of recesses (e.g., recesses 921, 922) of the fine uneven surface shape 92. The plurality of recesses (e.g., recesses 921, 922) included in the fine uneven surface shape 92 are provided on the surface of each of the plurality of recesses (e.g., recesses 911, 912) included in the uneven structure 91.

[0050] Type 9 may include a substrate 8 and a metal oxide provided on the substrate 8. The metal oxide provided on the substrate 8 may include fine metal oxides 3 and a metal oxide layer 4 between the fine metal oxides 3 and the substrate 8. Of the metal oxides provided on the substrate 8, the fine metal oxides 3 form a fine uneven shape 92. That is, each of the multiple protrusions (e.g., protrusions 920) of the fine uneven shape 92 is each of the multiple fine metal oxides 3. The spaces between the multiple fine metal oxides 3 are the multiple recesses (e.g., recesses 921, 922) of the fine uneven shape 92. Thus, Type 9 has a fine uneven shape of metal oxide. When focusing on the metal oxide, the term refers to the fine metal oxides 3, and when focusing on the fine uneven shape, the term refers to the fine uneven shape 92.

[0051] As shown in Figure 3C, the manufacturing method of this embodiment includes the step of forming a metal layer 1 on a mold 9 having a fine uneven surface 92, onto which the fine uneven surface 92 has been transferred. By transferring the fine uneven surface 92, the metal layer 1 will have a second uneven surface structure 22 that reflects the fine uneven surface 92 of the mold 9. At this time, the metal layer 1 will also have a first uneven surface structure 21 that reflects the uneven surface shape of the uneven surface structure 91 of the mold 9. Specifically, a plurality of recesses (e.g., recesses 911, 912) of the uneven surface structure 91 of the mold 9 will be reflected in a plurality of protrusions (e.g., protrusions 211, 212) of the first uneven surface structure 21 shown in Figure 1. Also, a plurality of recesses (e.g., recesses 921, 922) of the fine uneven surface 92 of the mold 9 will be reflected in a plurality of protrusions (e.g., protrusions 221, 222) of the second uneven surface structure 22 shown in Figure 1.

[0052] As shown in Figure 3D, the manufacturing method of this embodiment further includes the step of adhering the substrate 5 to the side of the metal layer 1 of the light-absorbing heat-shielding film 10 that is opposite to the side on which the fine uneven shape 92 is transferred.

[0053] The manufacturing method of this embodiment includes a step of removing at least a portion of the mold 9 from above the metal layer 1, as shown in Figures 3F to 3H. In the step shown in Figure 3F, the base 8 of the mold 9 is removed. In the step shown in Figure 3G, the metal oxide layer 4 of the mold 9 is removed. In the step shown in Figure 3H, the fine metal oxide 3 of the mold 9 is removed. In the step shown in Figure 3H, the entire mold 9 is removed. Note that if the base 8 of the mold 9 is a translucent material such as glass, the metal layer 1 can be used as a light-absorbing heat-shielding film without removing the base 8. In other words, it can also be used as a light-absorbing heat-shielding member 100 having the form shown in Figures 3D and 3E.

[0054] Each of the steps shown in Figures 3A to 3H may be part of the manufacturing method for the light-absorbing heat-shielding film 10, or part of the manufacturing method for the light-absorbing heat-shielding member 100.

[0055] The method for manufacturing the light-absorbing heat-shielding film 10 of this embodiment includes a first step of forming a fine uneven shape of metal oxide on a substrate 8, and a second step of forming a metal layer 1 on the fine uneven shape of metal oxide. The method for manufacturing the light-absorbing heat-shielding member of this embodiment further includes a step of bonding a substrate 5 to the side of the metal layer 1 of the light-absorbing heat-shielding film 10 that is opposite to the side in contact with the fine uneven shape of metal oxide.

[0056] The first structure (first uneven structure 21) of the hierarchical microstructure in the light-absorbing heat-shielding film 10 reflects the roughness structure size of the base substrate used in the mold 9, and the second structure (second uneven structure 21) reflects the size of the fine uneven shape 92 of the metal oxide.

[0057] (Step 1: Process for creating a fine, uneven surface shape of metal oxide) In the first step, a fine, uneven shape of the metal oxide, which will become type 9, is formed.

[0058] First, prepare the base substrate. Hereinafter, the base substrate (substrate) will be referred to as the base body 8 to distinguish it from the substrate 5, but the base body 8 is synonymous with the base substrate or substrate. The base body 8 used can be any substrate 8 that has a micro-order uneven structure 81 on its surface, and examples include, but are not limited to, ground glass roughened with an abrasive or etching solution such as an acid or alkali, or a base body 8 processed with an electron beam. A micro-order structure may also be formed on a film coated on the surface and used as the base body 8.

[0059] As shown in Figure 3A, the uneven structure 81 of the base body 8 has a plurality of recesses (for example, recesses 811, 812) and a plurality of protrusions between the plurality of recesses (for example, protrusions 810 between recesses 811, 812).

[0060] As shown in Figure 3A, a film 7 containing aluminum is deposited on a substrate 8 having a micro-order uneven structure 81. Since the film 7 is deposited along the uneven structure 81 of the substrate 8, it has an uneven structure 71 that reflects the uneven structure 81 of the substrate 8. The uneven structure 71 of the film 7 has a plurality of recesses (e.g., recesses 711, 712) and a plurality of protrusions between the plurality of recesses (e.g., recesses 711, 712) (e.g., protrusions 710 between recesses 711, 712). The plurality of recesses (e.g., recesses 711, 712) of the film 7 reflect the plurality of recesses (e.g., recesses 811, 812) of the substrate 8, and the plurality of protrusions (e.g., protrusions 710) of the film 7 reflect the plurality of protrusions (e.g., protrusions 810) of the substrate 8.

[0061] As shown in Figure 3B, a fine metal oxide 3 with a fine uneven surface 92 is formed on the substrate 8. The fine metal oxide 3 with the fine uneven surface 92 is formed by the alteration of the film 7. Therefore, it is arranged along multiple recesses (e.g., recesses 711, 712) and multiple protrusions (e.g., protrusions 710) of the film 7. Thus, the fine metal oxide 3 with the fine uneven surface 92 also constitutes the uneven structure 91 in the uneven surface 90. Furthermore, as shown in Figure 3B, a metal oxide layer 4 originating from the film 7 may be formed between the substrate 8 and the fine metal oxide 3 with the fine uneven surface 92.

[0062] The material for the metal oxide with a finely textured surface is not particularly limited, but it is preferable that it be mainly composed of aluminum oxide. The finely textured surface can be formed by known vapor phase methods such as chemical vapor deposition (CVD) and physical vapor deposition (PVD), as well as by sol-gel liquid phase methods. These methods can be used to create a metal oxide with a finely textured surface containing plate-like crystals mainly composed of aluminum oxide. Among these, a method of growing plate-like aluminum oxide crystals by treating an aluminum-containing film with hot water is preferred.

[0063] Examples of aluminum-containing films 7 include aluminum oxide gel films formed by applying a sol-gel coating solution containing an aluminum compound, and films containing metallic aluminum formed by dry deposition methods such as vacuum deposition or sputtering. It is preferable to use an aluminum oxide gel film to form the fine surface texture of the metal oxide because it allows for easy adjustment of reactivity and the height of the fine surface texture of the metal oxide.

[0064] Aluminum compounds such as aluminum alkoxides, aluminum halides, and aluminum salts can be used as raw materials for aluminum oxide gel films. From the viewpoint of film-forming properties, it is preferable to use aluminum alkoxides.

[0065] Examples of aluminum compounds include aluminum alkoxides such as aluminum ethoxide, aluminum isopropoxide, aluminum-n-butoxide, aluminum-sec-butoxide, and aluminum-tert-butoxide. Other examples include their oligomers, aluminum halides such as aluminum chloride, aluminum salts such as aluminum nitrate, aluminum acetate, aluminum phosphate, and aluminum sulfate, as well as aluminum acetylacetonate and aluminum hydroxide.

[0066] Furthermore, the aluminum oxide gel film may contain other compounds. Examples of other compounds include zirconium, silicon, titanium, zinc alkoxides, halides, salts, and combinations thereof. By including other compounds in the aluminum oxide gel film, the height of the fine irregularities of the metal oxide formed can be increased compared to cases where these compounds are not included.

[0067] The aluminum oxide gel film is formed on the substrate 8 by applying a sol-gel coating solution containing an aluminum compound, as shown below. The sol-gel coating solution is prepared by dissolving the aluminum compound in an organic solvent. The amount of organic solvent relative to the aluminum compound is preferably about 20 times in molar ratio.

[0068] As organic solvents, alcohols, carboxylic acids, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, esters, ketones, ethers, or mixtures thereof can be used. Examples of alcohols include methanol, ethanol, 2-propanol, butanol, 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol. Further examples include 1-propoxy-2-propanol, 4-methyl-2-pentanol, 2-ethylbutanol, 3-methoxy-3-methylbutanol, ethylene glycol, diethylene glycol, and glycerin. Examples of carboxylic acids include n-butyric acid, α-methylbutyric acid, isovaleric acid, 2-ethylbutyric acid, 2,2-dimethylbutyric acid, 3,3-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3-methylpentanoic acid, and 4-methylpentanoic acid. Furthermore, examples include 2-ethylpentanoic acid, 3-ethylpentanoic acid, 2,2-dimethylpentanoic acid, 3,3-dimethylpentanoic acid, 2,3-dimethylpentanoic acid, 2-ethylhexanoic acid, and 3-ethylhexanoic acid. Examples of aliphatic or alicyclic hydrocarbons include n-hexane, n-octane, cyclohexane, cyclopentane, and cyclooctane. Examples of aromatic hydrocarbons include toluene, xylene, and ethylbenzene. Examples of esters include ethyl formate, ethyl acetate, n-butyl acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, and ethylene glycol monobutyl ether acetate. Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of ethers include dimethoxyethane, tetrahydrofuran, dioxane, and diisopropyl ether. Among these, it is preferable to use alcohol from the viewpoint of the stability of the sol-gel coating solution.

[0069] When using aluminum alkoxide as the aluminum compound, its high reactivity to water can cause rapid hydrolysis of the aluminum alkoxide due to moisture in the air or the addition of water, resulting in turbidity and precipitation of the sol-gel coating solution. To prevent this, it is preferable to add a stabilizer to the sol-gel coating solution to stabilize it. Suitable stabilizers include β-diketone compounds, β-ketoester compounds, and alkanolamines. Examples of β-diketone compounds include acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone, 3-methyl-2,4-pentanedione, and 3-ethyl-2,4-pentanedione. Examples of β-ketoester compounds include methyl acetoacetate, ethyl acetoacetate, butyl acetoacetate, hexyl acetoacetate, allyl acetoacetate, benzyl acetoacetate, and iso-propyl acetoacetate. Furthermore, 2-methoxyethyl acetoacetate, sec-butyl acetoacetate, tert-butyl acetoacetate, and iso-butyl acetoacetate are also suitable. Examples of alkanolamines include monoethanolamine, diethanolamine, and triethanolamine. The amount of stabilizer relative to the aluminum alkoxide is preferably about 1 in molar ratio.

[0070] A catalyst may be used to accelerate the hydrolysis reaction of aluminum alkoxides. Examples of catalysts include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, and ammonia.

[0071] Furthermore, water-soluble organic polymer compounds can be added to the aluminum oxide gel film as needed. The water-soluble organic polymer compounds readily dissolve from the aluminum oxide gel film upon immersion in hot water, thereby increasing the surface area for reaction between the aluminum compound and the hot water, enabling the formation of fine uneven surfaces at low temperatures and in a short time. In addition, by changing the type and molecular weight of the added organic polymer, it is possible to control the height of the formed fine uneven surfaces. Polyether glycols such as polyethylene glycol and polypropylene glycol are preferred as organic polymers because they readily dissolve from the aluminum oxide gel film upon immersion in hot water. The amount of polyether glycols to the weight of the aluminum compound in the aluminum oxide gel film is preferably in the range of 0.1 to 10 times by weight.

[0072] The method for forming the fine surface texture of metal oxides will be described in detail with reference to Figures 3A and 3B.

[0073] First, in the process shown in Figure 3A, an aluminum compound, and optionally other compounds, stabilizers, and water-soluble organic polymer compounds, are dissolved or suspended in an organic solvent to prepare a sol-gel coating solution. This sol-gel coating solution is applied to a substrate 8 and dried to form an aluminum oxide gel film as an aluminum-containing film 7. Alternatively, a film containing metallic aluminum as the aluminum-containing film 7 is formed on the substrate 8 by dry deposition such as vacuum deposition or sputtering. There are no particular restrictions on the material of the substrate 8, and various materials such as glass, plastic, and metal can be used. When forming an aluminum oxide gel film using a sol-gel coating solution that does not contain stabilizers, it is preferable to use an inert gas atmosphere such as dry air or dry nitrogen for the coating process. The relative humidity of the dry atmosphere is preferably 30% or less. As a solution coating method for forming the aluminum oxide gel film, known coating methods such as dipping, spin coating, spraying, printing, flow coating, and combinations thereof can be appropriately employed. The film thickness can be controlled by changing the pulling speed in the dipping method or the substrate rotation speed in the spin coating method, and by changing the concentration of the sol-gel coating solution. Drying can be done at room temperature for about 30 minutes. If necessary, drying or heat treatment can be performed at a higher temperature, and the higher the heat treatment temperature, the more stable the fine surface texture 92 of the fine metal oxide 3 can be formed by the immersion treatment described later. The preferred film thickness of the aluminum-containing film 7 is 100 nm to 600 nm, preferably 100 nm to 300 nm, and more preferably 100 nm to 200 nm.

[0074] Next, in the process shown in Figure 3B, the aluminum-containing film 7 is immersed in hot water to form aluminum oxide with a fine uneven surface. By immersing the aluminum oxide gel film in hot water, the surface layer of the aluminum oxide gel film undergoes gelatinization and other processes. Although some components dissolve, due to the differences in the solubility of various hydroxides in hot water, plate-like crystals mainly composed of aluminum oxide precipitate and grow on the surface layer of the aluminum oxide gel film. In addition, the metal oxide layer 4 (see Figure 1) containing amorphous gel of aluminum oxide is formed on the substrate 8. This forms the fine uneven surface 92 of the metal oxide layer 4 and the fine metal oxide 3 as described above (see Figure 1). Furthermore, if a film containing metallic aluminum is used instead of the aluminum oxide gel film, the aluminum reacts with hot water and is oxidized to aluminum oxide. Subsequently, the fine uneven surface 92 of the fine metal oxide 3 is formed on the surface of the film containing metallic aluminum, similar to the case where the aluminum oxide gel film is used. Therefore, if the substrate 8 mainly contains aluminum or aluminum oxide, the deposition of the aluminum-containing film 7 on the substrate 8 can be omitted. The temperature of the hot water is preferably 40°C or higher and less than 100°C. The immersion treatment time is preferably about 5 minutes to 24 hours. In the immersion treatment of an aluminum oxide gel film with other compounds added besides aluminum oxide, the difference in the solubility of each component in hot water is used to crystallize the plate-like crystals of aluminum oxide. Therefore, unlike the immersion treatment of an aluminum oxide gel film containing only aluminum oxide, the size of the plate-like crystals can be controlled over a wide range by changing the composition of the inorganic components. By adjusting the film thickness of the aluminum-containing film 7, the height of the fine unevenness 92 of the metal oxide layer 4 and the fine metal oxide 3 can also be adjusted. The average height of the fine unevenness 92 of the fine metal oxide 3 is preferably 100 nm to 1000 nm, and more preferably 100 nm to 500 nm. As a result, it becomes possible to control the fine unevenness formed by the plate-like crystals over the wide range mentioned above.

[0075] (Second step: Formation of metal layer 1) In the second step, a metal layer 1 is formed on the fine uneven surface of the metal oxide, thereby forming a metal layer 1 having a fine uneven surface portion 2 onto which the fine uneven surface 92 of the mold 9 has been transferred. Referring to Figure 3C, the step of forming the metal layer 1 on the fine uneven surface 92 of the metal oxide will be described below. As a method for forming the metal layer 1, metal plating is preferred, and electroless plating is even more preferred. In electroless plating, activation is performed by applying an aqueous solution containing a palladium compound such as palladium chloride, a gold compound such as gold chloride, a silver compound such as silver chloride, or a tin compound such as tin chloride to the fine uneven surface 92 of the metal oxide. Activation may also be performed by immersing the fine uneven surface 92 of the metal oxide together with the substrate 8 in an aqueous solution containing a dissolved palladium compound. After that, the metal layer 1 is deposited on the fine uneven surface 92 of the metal oxide using an electroless plating solution. The metal ions in the electroless plating solution correspond to the metal layer of the light-absorbing heat-shielding film in this embodiment. An electroless plating solution containing nickel ions, chromium ions, and zinc ions is preferred, and a nickel plating solution containing nickel ions is particularly preferred. The nickel plating solution may also contain phosphorus or boron components in addition to the nickel component. Examples of commercially available nickel plating solutions include the Top Nicolon series from Okuno Pharmaceutical Co., Ltd. The temperature of the plating solution in the electroless plating process is preferably 30°C to 98°C, and more preferably 50°C to 90°C. The time for performing the electroless plating process can be adjusted according to the thickness of the metal layer to be formed, and is usually from 30 seconds to 1 hour. In this way, a metal layer 1 is formed so as to fill the gaps in the fine uneven shape, and a metal layer 1 is formed that includes a fine uneven shape portion 2 on which the fine uneven shape 92 of the metal oxide has been transferred. At this time, the portion located above the apex of the protrusions (e.g., protrusions 910) of the uneven structure 91 (on the opposite side from the mold 9) becomes the base portion 11, and the portion located below the apex of the protrusions (e.g., protrusions 910) of the uneven structure 91 (on the side of the mold 9) becomes the fine uneven shape portion 2. In other words, a metal layer 1 is formed comprising the base portion 11, the first uneven structure 21 (first structure), and the second uneven structure 22 (second structure). Preferably, the metal layer 1 comprising the base portion 11, the first uneven structure 21 (first structure), and the second uneven structure 22 (second structure) is a plated layer.

[0076] Furthermore, it is preferable that the main components of the metal material of the metal layer 1 comprising the base portion 11, the first uneven structure 21, and the second uneven structure 22 are the same.

[0077] It is preferable to perform electroless plating so that the thickness of the metal layer 1 including the fine uneven shape portion 2 is 200 nm or more and 15,000 nm or less. The metal layer 1 is formed to cover the vertices of the protrusions (e.g., protrusions 910) of the uneven structure 91, and this portion becomes the base portion 11, so the thickness of the base portion 11 can be 200 nm or more and 15,000 nm or less. In addition, the average height of the second uneven structure 22 in the fine uneven shape portion 2 corresponds to the average height of the fine uneven shape 92 of the metal oxide, and is 100 nm or more and 1,000 nm or less. When the thickness of the metal layer 1 including the fine uneven shape portion 2 is 200 nm or more, the light-absorbing heat-shielding film of this embodiment exhibits excellent light-absorbing heat-shielding properties.

[0078] After performing the electroless plating treatment described above, electroplating may be performed on the side of the metal layer 1 opposite to the side on which the fine uneven surface 2 is provided in order to increase the thickness of the metal layer 1. Known electroplating solutions can be used for the electroplating treatment, and for example, an electroplating solution containing nickel ions, iron ions, copper ions, etc. as metal ions can be used. If the same metal as the metal of metal layer 1 is used for the electroplating treatment, the thickness of the metal layer can be increased by the electroplating treatment. If a different metal than the metal of metal layer 1 is used for electroplating on top of metal layer 1, the metal layer provided by the electroplating treatment becomes the substrate 5. In addition to inorganic salts that serve as raw materials for metal ions, conductive salts, salts for adjusting counterions, carboxylic acid-based additives to improve the homogeneity of the plating film, brighteners, etc. may be added to the electroplating solution as needed. Furthermore, the thickness of the metal layer 1 can be set to a desired thickness by adjusting the temperature of the electroplating solution, the current density, and the plating time during the electroplating process. If necessary, before the electroplating process, the side of the metal layer 1 opposite to the side with the fine uneven surface 2 may be activated with an aqueous solution containing an acid or the like. Furthermore, in order to improve the quality of the film formed by the electroplating process, in addition to stirring the electroplating solution during the electroplating process, a step to remove foreign matter from the electroplating solution may also be included.

[0079] (Step 3: Substrate bonding process) In the manufacturing of the light-absorbing and heat-shielding member of this embodiment, as shown in Figure 3D, the base material 5 is bonded to the surface of the metal layer 1 obtained above that is opposite to the surface on which the fine uneven shape portion 2 is provided. The shape and material of the base material 5 can be those described above. If the material of the base material 5 is metal, the metal that will become the base material 5 may be further laminated on the surface of the metal layer 1 that is opposite to the surface on which the fine uneven shape portion 2 is provided. As for the method of laminating the metal, it may be laminated by the electroplating treatment described above, or it may be laminated by physical vapor deposition such as sputtering. Also, if the material of the base material 5 is resin, the base material may be provided by depositing the resin that will become the base material 5 on the surface of the metal layer 1 that is opposite to the fine uneven shape 92 of the metal oxide, and then curing it. The base material 5 may be bonded to the metal layer 1 by an adhesive layer 6. The adhesive used for the adhesive layer 6 is not particularly limited, and any material that firmly bonds the base material 5 and the metal layer 1 is acceptable.

[0080] (Step 4: Etching process) The etching process will be explained in detail using a light-absorbing and heat-shielding member comprising a substrate 5 and an adhesive layer 6 as an example, as shown in Figures 3E to 3H. However, the process is similar for light-absorbing and heat-shielding members comprising only a substrate 5 without an adhesive layer 6, and for light-absorbing and heat-shielding films without a substrate 5 or adhesive layer 6. Note that Figure 3E is an inverted version of the light-absorbing and heat-shielding member shown in Figure 3D.

[0081] First, to obtain the light-absorbing heat-shielding member of this embodiment, the substrate 8 is removed as shown in Figure 3F. After the removal of the substrate 8, the light-absorbing heat-shielding member has a film 7 containing metallic aluminum or a metal oxide layer 4 on its surface. If the film contains metallic aluminum, visible light is reflected by the metallic aluminum, so as shown in Figure 3G, it is necessary to further remove the film containing metallic aluminum by etching. Also, if the metal oxide layer 4 is a layer containing an amorphous gel of aluminum oxide, the layer containing the amorphous gel of aluminum oxide is the metal oxide layer 4 of the light-absorbing heat-shielding member. Therefore, the layer containing the amorphous gel of aluminum oxide may be removed by etching to satisfy the required surface hardness and light absorption. As an etching method, wet etching, which dissolves the film containing metallic aluminum or the metal oxide layer 4 using an acid or alkaline solution, is preferred. Examples of acids include hydrochloric acid, nitric acid, and sulfuric acid. Examples of alkalis include sodium hydroxide and potassium hydroxide. From the viewpoint of work efficiency, an etching method using an alkaline solution is more preferred. The etching concentration is preferably in the range of a few percent to several tens of percent, and the etching time is preferably in the range of a few hours to several days. Also, as shown in Figure 3H, the fine metal oxide 3 of the fine uneven shape 92 may also be removed by etching. This makes it possible to form a metal layer 1 (in other words, a light-absorbing heat-shielding film 10 containing metal oxides attached to the fine uneven shape 2) with metal oxides attached to the fine uneven shape portion 2. A light-absorbing heat-shielding member in which the metal layer 1 containing the fine uneven shape portion 2 is bonded to the substrate 5 via an adhesive layer 6 achieves particularly excellent light absorption. Furthermore, the metal layer 1 with metal oxides attached to the fine uneven shape portion 2 also has very excellent light absorption, and the strength of the fine uneven shape portion 2 can also be improved, resulting in excellent durability and environmental resistance.

[0082] The remaining metal oxides such as aluminum oxide after etching (metal oxides adhering to the fine uneven surface area 2) can be detected by EDX or XPS measurements during surface or cross-sectional observation using SEM or TEM.

[0083] As described above, the degree of etching should be adjusted according to the balance between the light absorption performance and surface hardness of the desired light-absorbing heat-shielding member or film. Alternatively, the etching process in this step may be performed before the bonding process of the substrate 5, which is the third step, and then the substrate 5 may be bonded.

[0084] The light-absorbing heat-shielding member and light-absorbing heat-shielding film obtained in this embodiment include a metal layer 1 containing a fine uneven shape portion 2, and therefore absorbs visible light, resulting in low reflectivity in the visible light region and low far-infrared radiation. As a result, the reflectivity in the far-infrared region is high, and excellent light-absorbing heat-shielding properties can be achieved.

[0085] The light-absorbing heat-shielding film 10 of this embodiment can be provided on the surface of various components or articles to form a light-absorbing heat-shielding member 100. The light-absorbing heat-shielding film 10 of this embodiment is preferably used as a heat-generating element as a component or article. Examples of articles equipped with such heat-generating elements include batteries, engines, motors, and vehicles. Engines include reciprocating engines, rotary engines, diesel engines, gas turbine engines, jet engines, and rocket engines. Motors include DC motors, AC motors, PM motors, brush motors, stepping motors, induction motors, servo motors, ultrasonic motors, in-wheel motors, and linear motors. A transport device equipped with at least one of an engine and a motor may also be equipped with the light-absorbing heat-shielding film 10. Transport devices equipped with at least one of an engine and a motor are not limited to various vehicles such as automobiles and trains, but also include ships, aircraft such as drones, and various robots such as AGVs. The transport device is not limited to passenger transport, but may also be for freight transport, and may be operated remotely or autonomously. A hybrid vehicle is a vehicle equipped with a battery, an engine, and a motor. The light-absorbing heat-shielding film 10 and the light-absorbing heat-shielding member 100 of this embodiment can be used as stray light prevention and heat-shielding members inside optical equipment, or as interior and exterior components of space-related equipment such as artificial satellites, and can also be used as exterior films, solar collectors, etc. In addition, the light-absorbing heat-shielding film of this embodiment can be used for clothing, etc. Furthermore, the light-absorbing heat-shielding film of this embodiment may be used as a heat-shielding decorative film. For example, the light-absorbing heat-shielding film of this embodiment can be applied as a heat-shielding decorative film to the interior of vehicles, mobile devices, home appliances, parasols, tent equipment, etc. Various adhesives can be used when applying the light-absorbing heat-shielding film of this embodiment to the surface of a component or article. Therefore, the light-absorbing heat-shielding film of this embodiment can be applied to the surface of components and articles according to the purpose of use, and the surface of the component or article is not limited to being smooth, but may have two-dimensional or three-dimensional curved surfaces.

[0086] Conventionally, with infrared thermal imaging cameras, it has been difficult to identify the component or article to be detected when various components or articles are present within the field of view. Components or articles equipped with the light-absorbing heat-shielding film of this embodiment exhibit a difference in detected temperature compared to components or articles without the film. Therefore, using the light-absorbing heat-shielding film of this embodiment makes it possible to clearly identify components or articles. Typically, infrared thermal imaging cameras have a detection temperature error range of 2°C. Therefore, the detected temperature on the side of the light-absorbing heat-shielding film opposite to the surface in contact with the component or article must be 3°C or more lower than the detected temperature on the part of the component or article without the film. In this case, it becomes possible to more clearly identify the component or article as a heat-generating element. [Examples]

[0087] The embodiment will be described in more detail below using examples.

[0088] However, this embodiment is not limited to the following examples.

[0089] The reflectance spectrum in the visible light region of the examples was measured using a lens reflectance analyzer (product name: USPM-RU III, manufactured by Olympus Corporation).

[0090] The infrared reflectance spectrum measurements in the examples were performed using a Fourier transform infrared spectrophotometer (FT / IR-6600, manufactured by JASCO Corporation).

[0091] (Example 1) (Manufacturing of light-absorbing and heat-shielding materials) An aluminum oxide sol solution was prepared by dissolving aluminum-sec-butoxide (hereinafter also referred to as "Al(O-sec-Bu)3") and ethyl acetoethyl (hereinafter also referred to as "Âtiac") in 2-propanol (hereinafter also referred to as "IPA") and stirring at room temperature for approximately 3 hours. The molar ratio of each component in the aluminum oxide sol solution was Al(O-sec-Bu)3:Âtiac:IPA = 1:1:20. A 0.01 M dilute hydrochloric acid aqueous solution was added to the aluminum oxide sol solution so that the amount of hydrochloric acid added was twice the molar ratio of Al(O-sec-Bu)3, and the mixture was refluxed for approximately 6 hours to prepare a sol-gel coating solution. The sol-gel coating solution was applied to a quartz glass substrate (#1200) with a frosted surface, which served as the base substrate, by spin coating to form a coating film. Subsequently, the coating film was heat-treated at 100°C for 1 hour to obtain a transparent aluminum oxide gel film. Next, the aluminum oxide gel film was immersed in 80°C hot water for 30 minutes, and then dried at 100°C for 10 minutes to form an aluminum oxide layer with a finely textured surface.

[0092] An aqueous palladium chloride solution was applied to an aluminum oxide layer with a finely textured surface by spin coating, and then dried at 100°C. Subsequently, the layer was immersed for 20 minutes in a nickel-phosphorus plating solution (phosphorus content approximately 1-2 wt%) set at 80°C to form a nickel layer as a metallic layer with a finely textured surface and a base layer beneath it. The light-absorbing heat-shielding film was then peeled from the quartz glass substrate, and an etching process was performed using a 3M aqueous sodium hydroxide solution at room temperature for 50 hours to produce a new light-absorbing heat-shielding film. The total thickness of the resulting light-absorbing heat-shielding film was approximately 10 μm.

[0093] (Observation of cross-sectional shape) Regarding the above-mentioned light-absorbing heat-shielding film, after forming a protective layer on the film surface, a cross-section was prepared using a focused ion beam processing device (product name: EM-TIC-3X, manufactured by Leica), and the cross-section was observed using a scanning electron microscope (SEM). The cross-sectional observation was performed using a scanning electron microscope (product name: Ultra55, manufactured by Carl Zeiss). Figures 4 and 5 show the observation images at 1000x (low magnification) and 100,000x (high magnification), respectively. From Figure 4, a rough structure originating from the base substrate is observed. On the other hand, from Figure 5, a fine structure of aluminum oxide micro-roughness is observed. Therefore, it can be seen that the obtained light-absorbing heat-shielding film is formed of two different hierarchical structures: a large structure (first structure) originating from the base substrate and a small structure (second structure) originating from the aluminum oxide micro-roughness. Furthermore, in the cross-sectional observation images, it can be seen that one convex part in the first structure contains five or more convex parts in the second structure. In other words, it can be seen that one convex part in the observation image observed at 1000x magnification in Figure 4 contains seven or more convex parts that are observed in the observation image observed at 100,000x magnification in Figure 5.

[0094] Table 1 shows the surface roughness of the obtained light-absorbing heat-shielding film.

[0095] Surface roughness was calculated from image analysis. The image analysis method was as follows: Image J (NIH Image, available from https: / / imagej.nih.gov / ij / ) was used for image processing. The average roughness Ra in the acquired cross-sectional SEM images was calculated as follows: First, the grayscale image was binarized, and the roughness curve of the uneven surface was digitized using a Line Graph. From the digitized roughness curve, the average line was obtained at low and high magnification as follows: At low magnification, the average line was obtained by fitting a linear equation to the digitized roughness curve using the least squares method. At high magnification, the average line was obtained by smoothing the digitized roughness curve with a Savitzky-Golay filter. The difference between the digitized roughness curve and the average line was defined as Y, and the direction of the average line was defined as X, and the average roughness Ra was calculated according to equation (1).

[0096] The first structure of the light-absorbing heat-shielding film obtained in Example 1 had an average roughness Ra of 0.2 μm and a maximum height Rz of 1.3 μm. The second structure had an average roughness Ra of 36 nm and a maximum height Rz of 165 nm.

[0097] (Evaluation of light-absorbing and heat-shielding materials) The reflectance spectra in the visible light region and the infrared region of the light-absorbing heat-shielding material obtained in Example 1 were measured. The reflectance spectra were measured using a lens reflectance meter (product name: USPM-RU III, manufactured by Olympus Corporation), and the reflectance spectra in the infrared region were measured using a Fourier transform infrared spectrophotometer (product name: FT / IR-6600, manufactured by JASCO Corporation). The results of the visible light region reflectance spectrum measurement are shown in Figure 6, and the results of the infrared region reflectance spectrum measurement are shown in Figure 7. Table 1 shows the reflectance in the visible light and infrared regions obtained from the reflectance spectrum measurements of the light-absorbing heat-shielding material. In Table 1, materials with low reflectance in the visible light region and excellent absorbance are designated as A, and materials with high reflectance toward longer wavelengths in the mid-infrared and far-infrared regions and excellent heat-shielding properties are also designated as A.

[0098] As shown in Figure 6, the light-absorbing and heat-shielding member of this embodiment has a low reflectance in the visible light region, indicating that it has excellent light absorption properties.

[0099] As shown in Figure 7, the light-absorbing heat-shielding member of this embodiment exhibits excellent heat-shielding properties because its reflectivity increases toward longer wavelengths in the mid-infrared and far-infrared regions.

[0100] Furthermore, Table 1 shows the results of photographing the light-absorbing heat-shielding material from eight directions with different shooting angles of 45° each, using a thermal imaging camera (infrared camera).

[0101] In Table 1, items with no reflection of ambient light sources from any angle and minimal glare from ambient light sources were designated as A. Items with some angles where the heat-shielding subject is difficult to see due to reflection from ambient light sources (high reflection of light from the light source (glare)) were designated as B.

[0102] (Example 2) An absorbent and heat-shielding film was manufactured in the same manner as in Example 1, except that the base substrate was changed to #600 frosted glass.

[0103] (Example 3) An absorbent and heat-shielding film was manufactured in the same manner as in Example 1, except that the base substrate was changed to #400 frosted glass.

[0104] (Example 4) An absorbent and heat-shielding film was manufactured in the same manner as in Example 1, except that the base substrate was changed to #240 frosted glass.

[0105] (Example 5) An absorbent and heat-shielding film was manufactured in the same manner as in Example 1, except that the base substrate was changed to #120 frosted glass.

[0106] Table 1 shows the surface roughness of the light-absorbing heat-shielding films manufactured in Examples 1 to 5, and the reflectance in the visible light and infrared regions obtained from reflection spectrum measurements in the visible light and infrared regions.

[0107] (Example 6) An article (hereinafter referred to as "article with light-absorbing heat-shielding film") was fabricated by attaching the light-absorbing heat-shielding film manufactured in Example 1 to the surface of a plate-shaped stainless steel (SUS). An article identical to the article with the light-absorbing heat-shielding film except for the absence of the light-absorbing heat-shielding film (hereinafter referred to as "article without light-absorbing heat-shielding film") was placed on a heater, and when the surface temperature of the article without the light-absorbing heat-shielding film reached 40°C, the surface temperatures of the article with the light-absorbing heat-shielding film and the article without the light-absorbing heat-shielding film were measured using an infrared thermography device (model: H2640, manufactured by Japan Avionics Co., Ltd.). The surface temperature measurement environment was room temperature, and the distance between the article and the measuring device was approximately 40 cm. The surface temperature of the article with the light-absorbing heat-shielding film was approximately 30°C, which was approximately 10°C lower than the surface temperature of the article without the light-absorbing heat-shielding film. Furthermore, when the surface temperature of an article without the light-absorbing heat-shielding film was set to approximately 60°C, the surface temperature of an article with the light-absorbing heat-shielding film was approximately 36°C, which was about 24°C lower. From the above, it was found that the light-absorbing heat-shielding film of this embodiment has excellent heat-shielding properties. A clear temperature difference was observed between the detected temperature of the article and the actual temperature, indicating that the article could be identified using an infrared thermal imaging camera.

[0108] Furthermore, it was confirmed that the article equipped with the light-absorbing heat-shielding film manufactured in Example 1 suppressed reflections of ambient light sources.

[0109] Furthermore, the light-absorbing heat-shielding films obtained in Examples 2 to 5 were also evaluated in the same manner. As a result, the detected temperature on the side of the light-absorbing heat-shielding film opposite to the surface in contact with the component or article was 3°C or more higher than the detected temperature on the part of the component or article where the light-absorbing heat-shielding film was not provided, confirming that heat shielding properties were exhibited. It was also found that reflections of ambient light sources were suppressed in the same way as in the article of Example 1.

[0110] (Comparative example) An absorbent heat-shielding film was manufactured in the same manner as in Example 1, except that the base substrate was changed to mirror-polished glass. Reflectance spectra in the visible light region and the infrared region were measured and images were taken using a thermal imaging camera (infrared camera) under the same conditions as the absorbent heat-shielding member in Example 1. The results are shown in Figures 6 and 7 and Table 1.

[0111] [Table 1]

[0112] From the above, it was found that the article of this embodiment has excellent light absorption and heat shielding properties while suppressing reflections of ambient light sources.

[0113] This embodiment makes it possible to provide a light-absorbing heat-shielding film and a light-absorbing heat-shielding member that absorb visible light and near-infrared rays (low reflectivity) and emit little far-infrared radiation (high reflectivity), which are usually incompatible.

[0114] The present invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are attached to make the scope of the invention public.

[0115] This application claims priority based on Japanese Patent Application No. 2020-125161, filed on 22 July 2020, and all of its contents are incorporated herein by reference.

Claims

1. A light-absorbing and heat-shielding film comprising a metal layer, The aforementioned metal layer is In the direction of extension of the light-absorbing heat-shielding film, the metal layer is continuous at the base and An uneven shaped portion provided on the base, Includes, The aforementioned uneven shape portion is A first uneven structure including multiple protrusions, A second uneven structure including multiple protrusions is provided on each of the aforementioned multiple protrusions, It has, The base extends beneath the plurality of protrusions included in the first uneven structure, The main component of the metal material of the base, the first uneven structure, and the second uneven structure is the same. The surface of the uneven shape portion is fitted with a metal oxide, The light-absorbing and heat-shielding film is characterized in that the metal component of the metal oxide is different from the metal component of the metal layer.

2. The light-absorbing heat-shielding film according to claim 1, characterized in that the metal oxide includes aluminum oxide.

3. A light-absorbing heat-shielding film comprising a metal layer, The aforementioned metal layer is In the direction of extension of the light-absorbing heat-shielding film, the metal layer is continuous at the base and An uneven shaped portion provided on the base, Includes, The aforementioned uneven shape portion is A first uneven structure including multiple protrusions, A second uneven structure including multiple protrusions is provided on each of the aforementioned multiple protrusions, It has, The base extends beneath the plurality of protrusions included in the first uneven structure, The main component of the metal material of the base, the first uneven structure, and the second uneven structure is the same. The surface of the uneven shape portion is fitted with a metal oxide, The aforementioned metal oxide is characterized by containing aluminum oxide, thus providing a light-absorbing and heat-shielding film.

4. The light-absorbing heat-shielding film according to claim 1 or 3, characterized in that the metal material of the base, the first uneven structure, and the second uneven structure includes one selected from nickel, chromium, and zinc.

5. The light-absorbing heat-shielding film according to claim 1 or 3, characterized in that the thickness of the base portion is 200 nm or more.

6. The light-absorbing and heat-shielding film according to claim 1 or 3, characterized in that the metal oxide is provided between the plurality of protrusions included in the second uneven structure.

7. The light-absorbing heat-shielding film according to claim 1 or 3, characterized in that the metal oxide contains crystals mainly composed of aluminum oxide.

8. The light-absorbing and heat-shielding film according to claim 1 or 3, comprising a metal oxide layer covering the uneven shape portion, wherein the metal oxide is provided between the metal oxide layer and the metal layer.

9. The light-absorbing and heat-shielding film according to claim 1 or 3, further comprising a metal oxide layer covering the aforementioned uneven shaped portion.

10. The light-absorbing heat-shielding film according to claim 8, wherein the metal oxide layer comprises an amorphous gel of aluminum oxide.

11. The light-absorbing and heat-shielding film according to claim 1 or 3, characterized in that one of the plurality of protrusions included in the first uneven structure is provided with seven or more of the plurality of protrusions included in the second uneven structure.

12. The light-absorbing heat-shielding film according to claim 1 or 3, characterized in that the average roughness Ra1 of the first uneven structure is 0.1 μm or more and 5 μm or less, and the average roughness Ra2 of the second uneven structure is 1 nm or more and 50 nm or less.

13. The light-absorbing heat-shielding film according to claim 1 or 3, characterized in that the maximum height Rz1 of the first uneven structure is 1 μm or more and 10 μm or less, and the maximum height Rz2 of the second uneven structure is 100 nm or more and 800 nm or less.

14. Substrate and A light-absorbing heat-shielding film according to claim 1 or 3 is provided on the substrate, A light-absorbing and heat-shielding member characterized by comprising the following features.

15. The light-absorbing and heat-shielding member according to claim 14, further comprising an adhesive layer for bonding the light-absorbing and heat-shielding film to the substrate.

16. The light-absorbing and heat-shielding member according to claim 15, characterized in that the base material is made of metal.

17. Heating element and A light-absorbing and heat-shielding film comprising a metal layer, The article wherein the light-absorbing heat-shielding film shields the heat from a heating element, The aforementioned metal layer is The base and, An uneven shaped portion provided on the base, Includes, The aforementioned uneven shape portion is A first uneven structure including multiple protrusions, A second uneven structure including multiple protrusions is provided on each of the aforementioned multiple protrusions, It has, The base extends beneath the plurality of protrusions included in the first uneven structure, The main component of the metal material of the base, the first uneven structure, and the second uneven structure is the same. The surface of the uneven shape portion is fitted with a metal oxide, An article characterized in that the metal component of the metal oxide is different from the metal component of the metal layer.

18. A heating element, A light-absorbing and heat-shielding film comprising a metal layer, The article wherein the light-absorbing heat-shielding film shields the heat from a heating element, The aforementioned metal layer is The base and, An uneven shaped portion provided on the base, Includes, The aforementioned uneven shape portion is A first uneven structure including multiple protrusions, A second uneven structure including multiple protrusions is provided on each of the aforementioned multiple protrusions, It has, The base extends beneath the plurality of protrusions included in the first uneven structure, The main component of the metal material of the base, the first uneven structure, and the second uneven structure is the same. The surface of the uneven shape portion is fitted with a metal oxide, The article is characterized in that the metal oxide contains aluminum oxide.

19. The article according to claim 17 or 18, characterized in that the detected temperature on the side of the light-absorbing heat-shielding film opposite to the side of the heating element is 3°C or lower than the detected temperature in the portion of the heating element where the light-absorbing heat-shielding film is not provided.

20. The light-absorbing heat-shielding film according to claim 1 or 3 comprises, An article characterized in that the light-absorbing heat-shielding film suppresses reflections of surrounding light sources.

21. At least one of the engine and the motor, A transport device comprising a light-absorbing heat-shielding film according to claim 1 or 3.

22. A process of preparing a mold having an uneven shape, A step of forming a metal layer on which the uneven shape is transferred onto the mold, Includes, The aforementioned type has an uneven structure including a plurality of recesses, The aforementioned uneven shape includes a plurality of recesses provided on the surface of each of the plurality of recesses included in the uneven structure, The process further includes removing at least a portion of the aforementioned type from the metal layer, The aforementioned type includes a substrate and a metal oxide provided on the substrate. A method for manufacturing a light-absorbing heat-shielding film, characterized by removing at least a portion of the metal oxide adhering to the metal layer from above the metal layer after the removal step.

23. A process of preparing a mold having an uneven shape, A step of forming a metal layer on which the uneven shape is transferred onto the mold, A step of adhering a substrate to the side of the metal layer opposite to the side on which the uneven shape is transferred, Includes, The aforementioned type has an uneven structure including a plurality of recesses, The aforementioned uneven shape includes a plurality of recesses provided on the surface of each of the plurality of recesses included in the uneven structure, The step further includes removing at least a portion of the above type from the metal layer. The aforementioned type includes a substrate and a metal oxide provided on the substrate. A method for manufacturing a light-absorbing and heat-shielding member, characterized by removing at least a portion of the metal oxide adhering to the metal layer from above the metal layer after the removal step.

24. The manufacturing method according to claim 23, characterized in that the substrate is made of metal.

25. The aforementioned type includes a substrate and a metal oxide provided on the substrate. The manufacturing method according to claim 22 or 23, characterized in that the metal oxide forms the uneven shape.

26. The manufacturing method according to claim 22 or 23, characterized in that the aforementioned uneven shape is formed by immersing a film containing aluminum in hot water.

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