Light-absorbing heat-shielding film, colored heat-shielding member, article, and method for manufacturing colored heat-shielding member

Abstract

Provided is a light-absorbing heat-shielding film that can form a colored heat-shielding member having a desired color and reducing emissivity of infrared light. The light-absorbing heat-shielding film comprises a metal layer having a region having a first through-hole pattern, wherein a portion of the metal layer other than through-holes has an uneven structure, the average hole diameter of the through-holes is 400 nm or more and 8 μm or less, the average emissivity of infrared light having a wavelength of 8-14 μm is 70% or less, and the average reflectance of visible light having a wavelength of 400-750 nm is 10% or less.

Description

Light-absorbing heat-shielding film, colored heat-shielding member, article, and method for producing colored heat-shielding member

[0001] The present disclosure relates to a light-absorbing heat-shielding film, a colored heat-shielding member, an article, and a method for producing the colored heat-shielding member.

[0002] Conventionally, when it is desired to make an object used outdoors or the like blend into a natural or other background, a technique for suppressing reflection of visible light by a method such as painting the object with a color that harmonizes with the background color is known. However, when the object radiates heat, for example, in detection using infrared light such as a security camera, there are cases where it is desired to shield light so that the object does not stand out from the original detection target, but it has been difficult to achieve both a desired color and low thermal emissivity.

[0003] Patent Document 1 proposes a sheet in which a metal thin film layer and a colorant-containing resin layer are laminated, and the thermal emissivity on the surface thereof is distributed in multiple stages, as a technique for coloring a desired color and suppressing the emissivity of far-infrared light.

[0004] Japanese Unexamined Patent Publication No. 2003-260751

[0005] However, in the embodiment of Patent Document 1, the deposition of the metal film increases in order to reduce the emissivity of far-infrared light. When the amount of the metal film increases, the region of the colorant-containing resin layer decreases and the metallic luster becomes strong, making it difficult to color the film with a desired color. Conversely, if the region of the colorant-containing resin layer for coloring with a desired color is increased, the deposition of the metal portion decreases, and the emissivity of far-infrared light becomes high.

[0006] To solve the above problems, an example of an embodiment illustrating the present disclosure is a light-absorbing heat-shielding film including a metal layer having a plurality of through holes, wherein the metal layer has a fine uneven structure in a portion different from the plurality of through holes, the average hole diameter of the plurality of through holes is 400 nm or more and 8 μm or less, the average emissivity of infrared rays with wavelengths of 8 μm or more and 14 μm or less is 70% or less, and the average reflectance of visible light with wavelengths of 400 nm or more and 750 nm or less is 10% or less. Another example of an embodiment illustrating the present disclosure is a colored heat-shielding member having a laminated structure of the above light-absorbing heat-shielding film and a colored film, wherein the colored film is laminated on a main surface different from the main surface of the light-absorbing heat-shielding film that has the fine uneven structure. Another example of an embodiment illustrating this disclosure is a method for manufacturing a colored heat-shielding member, comprising: a first step of forming a fine uneven shape of a metal oxide; a second step of applying a metal layer to the fine uneven shape of the metal oxide to form a light-absorbing heat-shielding film having a fine uneven structure of metal; a third step of forming a light-absorbing heat-shielding film having a plurality of through holes from the light-absorbing heat-shielding film; and a fourth step of forming a laminated structure of the light-absorbing heat-shielding film having a plurality of through holes and a colored film, wherein the fourth step is a step of laminating the colored film on a main surface of the light-absorbing heat-shielding film having a plurality of through holes that is different from the main surface on which the fine uneven structure is located. Another example of an embodiment illustrating this disclosure is an article equipped with the above-described colored heat-shielding member.

[0007] According to this disclosure, it is possible to provide a colored heat shielding member that achieves coloring in a desired color and low thermal emissivity, a light-absorbing heat shielding film that can be used therefor, an article equipped with a colored heat shielding member, and a method for manufacturing a colored heat shielding member.

[0008] This is a schematic diagram showing an example of hole processing in a light-absorbing heat-shielding film. This is a schematic diagram of a light-absorbing heat-shielding film. This is an example of a process diagram showing one embodiment of the manufacturing method of the colored heat-shielding member of this embodiment. This is another example of a process diagram showing one embodiment of the manufacturing method of the colored heat-shielding member of this embodiment. This is another example of a process diagram showing one embodiment of the manufacturing method of the colored heat-shielding member of this embodiment. This is another example of a process diagram showing one embodiment of the manufacturing method of the colored heat-shielding member of this embodiment. This is another example of a process diagram showing one embodiment of the manufacturing method of the colored heat-shielding member of this embodiment. This is another example of a process diagram showing one embodiment of the manufacturing method of the colored heat-shielding member of this embodiment. This is another example of a process diagram showing one embodiment of the manufacturing method of the colored heat-shielding member of this embodiment. This is a graph showing the reflectance characteristics of the light-absorbing heat-shielding film obtained in Example 1. This is a graph showing the emissivity characteristics of the light-absorbing heat-shielding film obtained in Example 1.

[0009] Examples of embodiments for carrying out this disclosure will be described below with reference to the drawings. However, the embodiments described below are examples of one embodiment of the invention and are not limited thereto.

[0010] [First Embodiment] In the first embodiment, an example of an embodiment of a light-absorbing heat-shielding film and a colored heat-shielding member will be described. The light-absorbing heat-shielding film of this embodiment is a light-absorbing heat-shielding film that includes a metal layer having a plurality of through holes, wherein the metal layer has a fine uneven structure in a portion different from the plurality of through holes, the average pore diameter of the plurality of through holes is 400 nm or more and 8 μm or less, the average emissivity of infrared rays with wavelengths of 8 μm or more and 14 μm or less is 70% or less, and the average reflectivity of visible light with wavelengths of 400 nm or more and 750 nm or less is 10% or less.

[0011] Furthermore, the colored heat-shielding member using the light-absorbing heat-shielding film described later is a colored heat-shielding member having a laminated structure of a light-absorbing heat-shielding film and a colored film, wherein the colored film is laminated on a main surface of the light-absorbing heat-shielding film that is different from the main surface having a fine uneven structure.

[0012] Here, the main surface of the light-absorbing heat-shielding film that has a fine uneven structure refers to the main surface of the light-absorbing heat-shielding film that has a fine uneven structure or the main surface that is close to the fine uneven structure.

[0013] Figure 1 shows an example in which multiple through-holes 52 are formed in the light-absorbing heat-shielding film 51. The average pore diameter of the multiple through-holes is 400 nm to 8 μm, preferably 750 nm to 8 μm. This pore diameter makes it possible to transmit visible light while suppressing the transmission of far-infrared light.

[0014] Here, through-holes can be confirmed by observing the surface using an optical microscope or scanning electron microscope (SEM). The acquired surface observation image is binarized to separate the through-holes from the light-absorbing heat-shielding film portion. The outline of the through-hole is extracted from the binarized image, and its shape is fitted as a circle. The average diameter of the through-hole can be calculated by averaging the diameters of multiple approximated circles.

[0015] Light has different pore sizes that can be transmitted depending on its wavelength. By forming a certain pore size, it is possible to cut out light with wavelengths greater than that pore size. Therefore, metal films with multiple pore sizes are used as low-pass filters (LPFs) for optical films.

[0016] Furthermore, microwave ovens are an example of devices that utilize this property. Microwave oven doors are fitted with a perforated metal film. This film is designed to block the microwave (2.4 GHz) electromagnetic waves used in microwave ovens, while allowing the contents inside to be seen. In other words, the holes are designed to be large enough to block microwaves but allow visible light to pass through.

[0017] In the light-absorbing heat-shielding film of this embodiment, multiple through-holes with a diameter that allows visible light to pass through but not far-infrared light are present in the light-absorbing heat-shielding film. As a result, when the light-absorbing heat-shielding film and a colored film are laminated together to form a colored heat-shielding member, the far-infrared rays emitted from the colored film placed on the lower surface of the light-absorbing heat-shielding film having multiple through-holes are cut off, while visible light is transmitted through the multiple through-holes, thereby suppressing radiation emission and achieving coloring.

[0018] Furthermore, in this disclosure, the relationship between the thickness D1 of the metal layer and the average hole diameter T1 of the multiple through holes may satisfy the following equation (3): 0.1 ≤ T1 / D1 ≤ 1.6 (3)

[0019] Thus, setting the relationship between the thickness D1 of the metal layer and the average hole diameter T1 of the multiple through holes within the above range is based on a thickness that allows the colored film to be easily seen through the through holes and is also easy to manufacture as a metal layer for a colored heat-shielding member.

[0020] The pore size is preferably between 400 nm and 8 μm. Since the detection wavelength of a typical far-infrared camera is between 8 μm and 14 μm, a pore size of 8 μm or less is preferred. Furthermore, to maintain the far-infrared radiation characteristics even better, a pore size of 4 μm or less is preferred.

[0021] Furthermore, since visible light needs to be transmitted, a pore diameter of 400 nm or larger is preferred. The shape of the pores is not limited, but for unpolarized light such as natural light, they are preferably circular, and the maximum diameter of the circle is preferably 8 μm or less. More preferably 4 μm or less.

[0022] Depending on the type of colored film forming the layered structure, the visible light may be polarized. In that case, it does not need to be circular, but the diameter in the direction perpendicular to the polarization direction is preferably 8 μm or less, and more preferably 4 μm or less. The parallel direction is not limited.

[0023] The method for creating the through-holes is not limited; any method that can form through-holes is acceptable. This can be selected from methods such as etching, punching, and laser processing. Furthermore, it is not necessary to form the holes with a single light-absorbing heat-shielding film; multiple light-absorbing heat-shielding films, each with through-holes of 8 μm or larger, can be layered to create the desired through-holes of 8 μm or less.

[0024] In other words, the multiple through holes may be formed based on a laminated structure of a first metal sublayer having a group of through holes with a first average hole diameter and a second metal sublayer having a group of through holes with a second average hole diameter, or they may be formed in a single metal layer. Furthermore, if it is a laminated structure, the first metal sublayer and the second metal sublayer may be bonded together. Specifically, they may be bonded together in areas other than the through holes.

[0025] In the former case, the average diameter of the multiple through holes may be smaller than the first average diameter and the second average diameter. Note that the term "metal sublayer" here refers to a portion of the layered structure when the metal layer is formed from a laminated structure of multiple sublayers.

[0026] Furthermore, the average emissivity of infrared radiation with wavelengths between 8 μm and 14 μm can be calculated by measuring the reflectance spectrum in the infrared region and averaging it over the desired wavelength. Using a Fourier transform infrared spectrophotometer, and based on the relationship between the law of conservation of energy and Kirchhoff's laws, the transmittance of the present invention is approximately 0%, so the emissivity % is the value obtained by subtracting the reflectance % from 100%. This makes it possible to measure the average emissivity.

[0027] <Light-absorbing heat-shielding film> Figure 2 shows the film shape of the light-absorbing heat-shielding film. The light-absorbing heat-shielding film of this embodiment has a metal layer 1 containing a fine uneven structure (uneven structure 2) on the main surface of the film, and the portion of the metal layer that is different from the multiple through holes has the fine uneven structure. The metal layer 1 further includes a base portion 11 that forms the surface of the metal layer 1. A metal with high conductivity is preferred as the material of the metal layer 1.

[0028] Examples of highly conductive metals include silver, copper, gold, aluminum, magnesium, tungsten, cobalt, zinc, nickel, and chromium, with nickel, zinc, and chromium being preferred, and nickel being particularly preferred. In other words, it is preferable that the metal layer 1 contains at least one selected from the group consisting of nickel, chromium, and zinc. It is also preferable that the uneven structure 2 provided on the surface of the metal layer 1 be made of a highly conductive metal, and more preferably made of the same metal as the base 11 of the metal layer 1.

[0029] The base portion 11 is the part where the metal layer 1 is continuous throughout the entire region 101, while the uneven structure 2 is the part where the metal layer 1 is discontinuous throughout the entire region 101. In Figure 2, the boundary between the base portion 11 and the uneven structure 2 is shown by a dashed line.

[0030] The uneven surface structure 2 includes a first uneven surface structure 21 and a second uneven surface structure 22. An object having the uneven surface structure 2 is an uneven surface structure, and since the uneven surface structure 2 is part or all of the uneven surface structure, the uneven surface structure 2 can also be called an uneven surface structure.

[0031] In this embodiment, the light-absorbing heat-shielding film has a hierarchical structure 2 consisting of a first uneven structure (first uneven structure 21) and a second uneven structure (second uneven structure 22), and it is preferable that the second uneven structure (second uneven structure 22) is formed on the first uneven structure (first uneven structure 21).

[0032] 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 presence of the first uneven structure 21 allows the light-absorbing heat-shielding film 100 to change its infrared emissivity, thereby controlling its heat-shielding effect. The protrusions 211 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 do not necessarily have to contain the metal layer 1; they are spaces where materials other than the metal layer 1 may exist.

[0033] 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 presence of the second uneven structure 22 reduces the reflectivity of visible light in the light-absorbing heat-shielding film 100, thus providing a light-absorbing effect. Note that the protrusions 221 and 222 of the second uneven structure 22 are part of the metal layer 1, and the recesses 220 of the second uneven structure 22 do not necessarily have to be part of the metal layer 1; these are spaces where materials other than the metal layer 1 may exist.

[0034] Furthermore, it is preferable that the second uneven structure 22 is formed on the upper surface of the first uneven structure 21. By doing so, the light-absorbing heat-shielding film 100 has an enhanced light-absorbing effect. In other words, the second uneven structure 22 is provided on the upper surface of each of the multiple protrusions (for example, protrusions 211 and 212) included in the first uneven structure 21.

[0035] It is preferable that the main components of the metal materials for the first uneven structure 21 and the second uneven structure 22 are the same. By constructing the base 11, the first uneven structure 21, and the second uneven structure 22 from a common metal material (i.e., a single-layer metal layer 1), superior light absorption and heat shielding properties can be achieved compared to when they are constructed from different metal materials (i.e., multiple layers of metal).

[0036] The metal layer 1, which is an uneven structure in the light-absorbing heat-shielding film 100, has a base portion 11 made of a metal material having the same main component as the first uneven structure 21 and the second uneven structure 22, located below the first uneven structure 21. The base portion 11 extends continuously below a plurality of protrusions (for example, protrusions 211 and 212) included in the first uneven structure 21.

[0037] In contrast, the uneven structure 2 is discontinuous in the metal layer 1 due to the recesses of the first uneven structure 21 (for example, recess 210) or the recesses 220 of the second uneven structure 22. That is, the protrusions of the first uneven structure 21 (for example, protrusions 211 and 212) are discontinuous due to the recesses 210.

[0038] Furthermore, the protrusions of the second uneven structure 22 (for example, protrusions 221 and 222) are discontinuous due to the recesses 220. In this specification, the main component refers to the component that has the highest molar content among multiple components when the material consists of multiple components.

[0039] The light-absorbing heat-shielding film of this embodiment has an average emissivity of 70% or less for infrared rays with wavelengths of 8 μm to 14 μm, and an average reflectivity of 10% or less for visible light with wavelengths of 400 nm to 750 nm. To achieve this, Ra1, Ra2, Rz1, and Rz2 as described below are preferred.

[0040] Preferably, the average roughness Ra1 of the first uneven structure (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 (second uneven structure 22) is 1 nm or more and 50 nm or less. This makes the effects of providing the first uneven structure 21 and the second uneven structure 22 more pronounced.

[0041] Here, the average roughness of the uneven structure 2, or the average roughness of the uneven structure 2 to which a transparent metal oxide described later is attached, means the arithmetic mean roughness specified in "Definitions and Designation of Surface Roughness" of JIS-B-0601.

[0042] From the roughness curve, only the reference length is extracted in the direction of its average line, the X-axis is taken in the direction of the average line of the extracted portion, the Y-axis is taken in the direction of the vertical magnification, and when the roughness curve is expressed as y = f(x), it is determined by the following formula (A). In formula (A), Ra is the average roughness (nm), L is the reference length, and F(X, Y) is the height at the measurement point (X, Y) where the X coordinate is X and the Y coordinate is Y.

[0043] Further, in the light-absorbing heat-shielding film 100 according to the present embodiment, the maximum height Rz1 of the first uneven structure (first uneven structure 21) on the surface of the metal layer 1 is preferably 1 μm or more and 10 μm or less, and the maximum height Rz2 of the second uneven structure (second uneven structure 22) is preferably 100 nm or more and 800 nm or less. By doing in this way, the effect provided by the first uneven structure 21 and the second uneven structure 22 becomes more remarkable.

[0044] As a range of the average roughness of the uneven structure more suitable for realizing an average emissivity of 70% or less, the average roughness Ra1 of the first uneven structure is 0.1 μm or more and 1 μm or less, and the average roughness Ra2 of the second uneven structure is 1 nm or more and 50 nm or less.

[0045] Moreover, as a range of the maximum height of the uneven structure more suitable for realizing an average emissivity of 70% or less, the maximum height Rz1 of the first uneven structure is 1 μm or more and 7 μm or less, and the maximum height Rz2 of the second uneven structure is 100 nm or more and 300 nm or less.

[0046] Accordingly, it is most preferable that the average roughness Ra1 of the first uneven structure is 0.1 μm or more and 1 μm or less, the average roughness Ra2 of the second uneven structure is 1 nm or more and 50 nm or less, the maximum height Rz1 of the first uneven structure is 1 μm or more and 7 μm or less, and the maximum height Rz2 of the second uneven structure is 100 nm or more and 300 nm or less.

[0047] Here, the maximum height of the uneven structure 2, or the maximum height of the uneven structure 2 with the transparent metal oxide attached (described later), refers to the maximum height specified in JIS-B-0601 "Definition and Indication of Surface Roughness". This is calculated by extracting only a reference length from the roughness curve in the direction of its average line, and measuring the distance between the peak line and the valley line of the extracted portion in the direction of the vertical scaling factor of the roughness curve.

[0048] This valley bottom line may correspond to the boundary between the base 11 and the uneven structure 2, as shown by the dashed line in Figure 2. The average roughness Ra and maximum height Rz of the uneven structure 2 can be determined by observing the cross-section of the light-absorbing heat-shielding film 100 of this embodiment with a scanning electron microscope or the like.

[0049] The light-absorbing heat-shielding film 100 of this embodiment includes metal oxide layers 3 and 4 provided on one main surface of the metal layer 1, but the metal oxide layers 3 and 4 are not necessarily required.

[0050] It is preferable that a transparent metal oxide layer 3 is attached to the surface of the uneven structure 2. In other words, it is preferable that the light-absorbing heat-shielding film 100 contains a transparent metal oxide layer 3 on the surface of the uneven structure which is the metal layer 1.

[0051] Preferably, the metal oxide layer 3 is provided over the entire surface of the uneven structure, but it is sufficient if it is provided on at least the protrusions (for example, protrusions 221 and 222). Preferably, the metal component of the metal oxide layer 3 attached to the surface of the uneven structure 2 is different from the metal component of the metal layer 1.

[0052] In other words, for example, if the material of metal layer 1 is mainly nickel, then the metal oxide layer 3 adhering to the surface of the uneven structure 2 is mainly an oxide of a metal other than nickel. Therefore, the metal oxide layer 3 adhering to the surface of the uneven structure 2 can be distinguished from a metal oxide that has the same metal components as metal layer 1, formed by the natural oxidation of metal layer 1, etc.

[0053] In this specification, the metal oxide layers 3 and 4 may be referred to as metal oxides. The metal oxide layer 3 is provided between a plurality of protrusions (for example, protrusions 221 and 222) included in the second uneven structure 22. That is, it is preferable that the metal oxide layer 3 fills the recesses of the second uneven structure 22 (for example, the recess 220 between protrusions 221 and 222) and is formed in a film-like manner.

[0054] Furthermore, the light-absorbing heat-shielding film 100 of this embodiment may further include a transparent metal oxide layer 4 that covers the surface of the metal oxide layer 3 that is not in contact with the uneven structure 2. Preferably, the metal oxide layer 4 covers the uneven structure 2, and the metal oxide layer 3 is provided between the metal oxide layer 4 and the metal layer 1.

[0055] The material of the metal oxide layer 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).

[0056] Plate-like crystals mainly composed of aluminum oxide are formed from crystals mainly composed of aluminum oxides, hydroxides, or hydrates thereof, with boehmite being a particularly preferred crystal.

[0057] Here, the plate-like crystals mainly composed of aluminum oxide may be plate-like crystals consisting solely of aluminum oxide, or they may be plate-like crystals containing trace amounts of zirconium, silicon, titanium, zinc, etc.

[0058] In this way, the light-absorbing heat-shielding film 100 can protect the uneven structure 2 by comprising the metal oxide layer 3. Furthermore, when the metal oxide layer 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.

[0059] 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 100 in 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.

[0060] <Other> The uneven structure 2, the metal oxide layer 3, and the elements of aluminum, silicon, etc. in the metal oxide layer 4 can be detected by surface measurements using a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

[0061] Furthermore, these elements can also be detected by energy-dispersive X-ray analysis (EDX) or X-ray electron spectroscopy (XPS) measurements during cross-sectional observation. Similarly, metallic elements such as silver, copper, gold, aluminum, magnesium, tungsten, cobalt, zinc, nickel, and chromium in metal layer 1 can also be detected by surface measurements using scanning electron microscopy (SEM) or transmission electron microscopy (TEM).

[0062] Similarly, when a coating layer is formed on a colored heat-shielding film, elements such as silicon and fluorine in the coating layer can be detected by surface measurements using scanning electron microscopy (SEM) or transmission electron microscopy (TEM). They can also be detected by energy-dispersive X-ray analysis (EDX) or X-ray electron spectroscopy (XPS) measurements during cross-sectional observation.

[0063] When a textured structure 2, a metal oxide layer 3, or a metal oxide layer 4 is 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 proportion of metal elements constituting the metal layer 1 and the textured structure 2 increases relatively from the surface (metal oxide layer 4) towards the interior (metal layer 1), until ultimately only metal elements are detected.

[0064] <Colored Heat-Shielding Member> By forming a laminated structure of a light-absorbing heat-shielding film having multiple through holes formed as described above and a colored film, a colored heat-shielding member can be manufactured that achieves the desired color.

[0065] The colored heat-shielding member of this embodiment is a colored heat-shielding member having a laminated structure of a light-absorbing heat-shielding film having a plurality of through holes and a colored film, wherein the colored film is laminated on a main surface different from the main surface on the side of the light-absorbing heat-shielding film having a plurality of through holes that has an uneven structure. In other words, it is preferable that the colored heat-shielding member has a structure in which the colored film is laminated on a main surface different from the main surface on the side of the light-absorbing heat-shielding film that has the fine uneven structure (the side with the fine uneven structure).

[0066] The colored film may consist of a single colored layer, or it may include a colored layer and a layer different from the colored layer. In the latter case, the colored layer of the colored film may be laminated on a main surface different from the main surface on the uneven structure side of the light-absorbing heat-shielding film having multiple through holes.

[0067] In this embodiment, the colored layer is a colored layer, such as a paint or other colorant containing a pigment that has the maximum absorption wavelength in the visible light region.

[0068] The proportion of the light-absorbing heat-shielding film in the colored heat-shielding member (in this disclosure, S1 / (S1+S2) may be referred to as the area ratio S) preferably satisfies the following formula (1): 0.1 ≤ S1 / (S1+S2) ≤ 0.9 (1) (However, in formula (1), when the colored heat-shielding member is viewed from above from the light-absorbing heat-shielding film side, any 100 cm ２ (In this region, let S1 be the area of ​​the light-absorbing heat-shielding film and S2 be the area of ​​the colored film.)

[0069] Here, S2 is the area where the colored film is visible when the colored heat-shielding member is viewed from above from the light-absorbing heat-shielding film side, and may be the total area of ​​the pores. Furthermore, the colored heat-shielding member may satisfy formula (1) and the surrounding area may not satisfy formula (1), and these may be an integrated structure.

[0070] For example, the area surrounding the colored heat-shielding member may have an edge area that becomes the bonding area with other colored heat-shielding members when attached to the object. Furthermore, any "100 cm ２ The "area" can also be confirmed, for example, by taking an image of a colored heat-shielding material from above.

[0071] Furthermore, it is preferable that the area ratio S of the colored heat-shielding member satisfies the following formula (2): 0.3 ≤ S1 / (S1 + S2) ≤ 0.9 (2) (However, in formula (2), when the colored heat-shielding member is viewed from above from the light-absorbing heat-shielding film side, any 100 cm ２ Let S1 be the area of ​​the light-absorbing heat-shielding film and S2 be the area of ​​the colored film in the region. This is because if S is large, the proportion of the colored film decreases, which can make it difficult to achieve the desired color.

[0072] When creating a colored film that harmonizes naturally, colors such as camouflage, gray, or olive drab can be used. These colors are characterized by their low brightness and saturation. When reproducing low-brightness, low-saturation colors by mixing, the hue of the two films is important. If one is a light color, the other needs to be a dark color. However, if the area proportion of the light color is high, it becomes difficult to reproduce the desired olive drab color.

[0073] In the colored heat-shielding member of this embodiment, a light-absorbing heat-shielding film with low reflectivity in the visible light range is used. Therefore, because the film is black, even if the area ratio of the light-absorbing heat-shielding film in the colored heat-shielding member is increased, it is possible to reproduce the desired gray or olive drab color by brightening the color of the colored film. The light-absorbing heat-shielding film forming the colored heat-shielding member of this embodiment has multiple through holes, which makes it possible to achieve a desired color that harmonizes naturally and to reduce the far-infrared radiation emissivity.

[0074] When the color space of the target colored heat-shielding member is L*a*b*, the color spaces L*2, a*2, and b*2 of the colored film are determined by the area ratio S of the light-absorbing heat-shielding film described above. If the color spaces L*1, a*1, and b*1 of the colored heat-shielding film to be used are L*1 = 22.1, a*1 = 3.4, and b*1 = 3.4 respectively, then the following relationships hold: L* = (-0.7S + 0.91)L*2 + 5.2S + 11.5 a* = (-0.7S + 0.91)a*2 b* = (-0.7S + 0.91)b*2 Therefore, the color of the colored film that can reproduce the target color may be determined after calculating the area ratio, or the area ratio may be adjusted after determining the color of the colored film. In this embodiment, the colored film has an L* of 20 or more in the Lab color space (L*, a*, b*).

[0075] [Second Embodiment] In the second embodiment, an example of a method for manufacturing a colored heat-shielding member will be described. The method for manufacturing a colored heat-shielding member of this embodiment comprises: a first step of forming a fine uneven shape of a metal oxide; a second step of applying a metal layer on the fine uneven shape of the metal oxide to form a light-absorbing heat-shielding film having a fine uneven structure; a third step of forming a plurality of through holes in the light-absorbing heat-shielding film; and a fourth step of forming a laminated structure of the light-absorbing heat-shielding film having the plurality of through holes and a colored film, wherein the fourth step is a step of laminating the colored film on a main surface of the light-absorbing heat-shielding film having the plurality of through holes that is different from the main surface on which the fine uneven structure is located, and the light-absorbing heat-shielding film has an average emissivity of 70% or less for infrared rays with a wavelength of 8 μm or more and 14 μm or less and an average reflectivity of 10% or less for visible light with a wavelength of 400 nm or more and 750 nm or less.

[0076] The method for manufacturing the light-absorbing heat-shielding film 100 of this embodiment will be described below with reference to Figures 3A to 3G. Note that some items described in the first embodiment may be omitted in the second embodiment to avoid repetition.

[0077] The method for manufacturing the light-absorbing heat-shielding film 100 of this embodiment may include 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.

[0078] The mold 9 has a fine uneven surface 91. The uneven surface formed by the fine uneven surface 91 is encompassed within the uneven surface 90. The fine uneven surface 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 fine uneven surface 91.

[0079] 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 fine uneven surface shape 91.

[0080] 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 a metal oxide layer 3 (also referred to as fine metal oxide 3 in this disclosure) and a metal oxide layer 4 between the fine metal oxide 3 and the substrate 8. Of the metal oxide provided on the substrate 8, the fine metal oxide 3 forms a fine uneven shape 92.

[0081] In other words, 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, mold 9 has a fine uneven shape of metal oxide. When referring to the fine uneven shape of metal oxide, it means the fine metal oxides 3 when focusing on the metal oxide, and it means the fine uneven shape 92 when focusing on the fine uneven shape.

[0082] The process for creating the light-absorbing heat-shielding film may include the step of forming a metal layer 1 on a mold 9 having a fine uneven surface 92, as shown in Figure 3C. By transferring the fine uneven surface 92, the metal layer 1 will have a second uneven structure 22 that reflects the fine uneven surface 92 of the mold 9.

[0083] In this case, the metal layer 1 also has a first uneven structure 21 that reflects the uneven shape of the fine uneven shape 91 of the mold 9. More specifically, the multiple recesses (for example, recesses 911, 912) of the fine uneven shape 91 of the mold 9 are reflected in the multiple protrusions (for example, protrusions 211, 212) of the first uneven structure (first uneven structure 21) shown in Figure 2. In addition, the multiple recesses (for example, recesses 921, 922) of the fine uneven shape 92 of the mold 9 are reflected in the multiple protrusions (for example, protrusions 221, 222) of the second uneven structure (second uneven structure 22) shown in Figure 2.

[0084] The process for creating the light-absorbing heat-shielding film may include a step of removing at least a portion of the mold 9 from above the metal layer 1, as shown in Figures 3E to 3G. In the step shown in Figure 3E, the substrate 8 of the mold 9 is removed. In the step shown in Figure 3F, the metal oxide layer 4 of the mold 9 is removed. In the step shown in Figure 3G, the fine metal oxide 3 of the mold 9 is removed. In the step shown in Figure 3G, it is not necessary to remove all of it; some may remain.

[0085] The process for creating the light-absorbing heat-shielding film may include a first step of forming a fine uneven structure of metal oxide on a substrate 8, and a second sub-step of forming a metal layer 1 on the fine uneven structure of metal oxide.

[0086] The first structure (first uneven structure 21) of the hierarchical microstructure in the light-absorbing heat-shielding film 100 reflects the roughness structure size of the base substrate (i.e., substrate) used in the mold 9, and the second structure (second uneven structure 22) reflects the size of the fine uneven shape 92 of the metal oxide.

[0087] The following describes in detail each step of the manufacturing method for the light-absorbing heat-shielding film 100 of this embodiment. <First step: Step of forming a fine uneven shape of metal oxide> It is preferable that the first step includes a step of forming a fine uneven shape of metal oxide on a substrate. Therefore, in the first step, a fine uneven structure of metal oxide is formed, which will become the mold 9 for forming the metal layer.

[0088] The term "fine" in the fine surface irregularities described here refers to, for example, a surface with an average roughness Ra of 100 nm to 5000 nm.

[0089] First, a base substrate is prepared. Hereinafter, the base substrate will be referred to as a substrate 8 to distinguish it from the substrate 5 bonded with the adhesive layer 6, but the term substrate 8 is synonymous with base substrate or substrate. The substrate 8 used can be any substrate 8 having micro-order irregularities 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 substrate 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 substrate 8.

[0090] As shown in Figure 3A, the micro-order uneven shape 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).

[0091] As shown in Figure 3A, a film 7 containing aluminum is deposited on a substrate 8 having a micro-order uneven surface 81. Since the film 7 is deposited along the uneven surface 81 of the substrate 8, it has an uneven surface 71 that reflects the uneven surface 81 of the substrate 8. Therefore, the uneven surface 71 also has an uneven surface on the order of micrometers.

[0092] The uneven shape 71 of the film 7 has a plurality of recesses (for example, recesses 711, 712) and a plurality of protrusions between the plurality of recesses (for example, protrusions 710 between recesses 711, 712).

[0093] Multiple recesses in the film 7 (e.g., recesses 711, 712) reflect multiple recesses in the substrate 8 (e.g., recesses 811, 812), and multiple protrusions in the film 7 (e.g., protrusion 710) reflect multiple protrusions in the substrate 8 (e.g., protrusion 810).

[0094] Next, as shown in Figure 3B, a metal oxide layer 3 having a fine uneven surface 92 is formed on the substrate 8. Here, "formed on the substrate 8" includes cases where it is formed without direct contact with the substrate 8 (with a layer in between). The metal oxide layer 3 having a fine uneven surface 92 is formed by the alteration of the film 7. Therefore, it is arranged along multiple recesses (e.g., recesses 911, 912) and multiple protrusions (e.g., protrusions 920) of the film 7.

[0095] Therefore, the metal oxide layer 3 forming the fine uneven shape 92 also constitutes the fine uneven shape 91 in the uneven shape 90. As shown in Figure 3B, a metal oxide layer 4 originating from the film 7 can be formed between the substrate 8 and the metal oxide layer 3 forming the fine uneven shape 92.

[0096] The material with a fine, uneven metal oxide structure is not particularly limited, but it is preferable that it is mainly composed of aluminum oxide. The fine, uneven structure can be formed by known vapor phase methods such as chemical vapor deposition (CVD) and physical vapor deposition (PVD), as well as by liquid phase methods of sol-gels.

[0097] These methods make it possible to create a fine, uneven surface in metal oxides containing plate-like crystals mainly composed of aluminum oxide. Among these, the method of growing plate-like aluminum oxide crystals by treating an aluminum-containing film with hot water is preferred.

[0098] Therefore, it is preferable that the first step includes a step of obtaining the fine uneven shape 92 of the metal oxide by immersing a film containing aluminum in hot water. In other words, it is preferable that the first step includes a step of forming the fine uneven shape of the metal oxide by immersing a film containing aluminum in hot water.

[0099] 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 uneven surface of the metal oxide because it allows for easy adjustment of reactivity and the height of the fine uneven surface of the metal oxide.

[0100] 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.

[0101] Examples of aluminum compounds include aluminum alkoxides such as aluminum ethoxide, aluminum isopropoxide, aluminum-n-butoxide, aluminum-sec-butoxide, and aluminum-tert-butoxide.

[0102] Other examples include these oligomers, aluminum halides such as aluminum chloride, aluminum salts such as aluminum nitrate, aluminum acetate, aluminum phosphate, and aluminum sulfate, aluminum acetylacetonate, and aluminum hydroxide.

[0103] 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.

[0104] 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.

[0105] As organic solvents, alcohols, carboxylic acids, aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, esters, ketones, ethers, or mixtures thereof can be used.

[0106] Examples of alcohols include methanol, ethanol, 2-propanol, butanol, 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol.

[0107] Furthermore, examples of alcohols include 1-propoxy-2-propanol, 4-methyl-2-pentanol, 2-ethylbutanol, 3-methoxy-3-methylbutanol, ethylene glycol, diethylene glycol, and glycerin.

[0108] 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.

[0109] Furthermore, examples of carboxylic acids 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.

[0110] Examples of aliphatic or alicyclic hydrocarbons include n-hexane, n-octane, cyclohexane, cyclopentane, and cyclooctane. Examples of aromatic hydrocarbons include toluene, xylene, and ethylbenzene.

[0111] 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.

[0112] 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, alcohol is preferred for the stability of the sol-gel coating solution.

[0113] 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, potentially leading to turbidity and precipitation of the sol-gel coating solution.

[0114] To prevent these issues, it is preferable to add a stabilizer to the sol-gel coating solution to ensure stability. Suitable stabilizers include β-diketone compounds, β-ketoester compounds, and alkanolamines.

[0115] Examples of β-diketone compounds include acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone, 3-methyl-2,4-pentanedione, and 3-ethyl-2,4-pentanedione.

[0116] Examples of β-ketoester compounds include methyl acetoacetate, ethyl acetoacetate, butyl acetoacetate, hexyl acetoacetate, allyl acetoacetate, benzyl acetoacetate, and isopropyl acetoacetate.

[0117] Furthermore, examples of β-ketoester compounds include 2-methoxyethyl acetoacetate, sec-butyl acetoacetate, tert-butyl acetoacetate, and iso-butyl acetoacetate.

[0118] Examples of alkanolamines include monoethanolamine, diethanolamine, and triethanolamine. The amount of stabilizer relative to the aluminum alkoxide is preferably about 1 in molar ratio.

[0119] 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.

[0120] 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 when immersed in hot water, thereby increasing the surface area for reaction between the aluminum compound and the hot water, and enabling the formation of a fine, uneven structure at low temperatures and in a short time.

[0121] Furthermore, by changing the type and molecular weight of the added organic polymer, it becomes possible to control the height of the formed fine uneven surface. As the organic polymer, polyether glycols such as polyethylene glycol and polypropylene glycol are preferred because they readily dissolve from the aluminum oxide gel film when immersed 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.

[0122] A method for forming a fine, uneven surface on a metal oxide will be described in detail with reference to Figures 3A and 3B. First, in the step 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.

[0123] This sol-gel coating liquid is applied to the substrate 8 and dried to form an aluminum oxide gel film as an aluminum-containing film 7. Alternatively, a film containing metallic aluminum as an aluminum-containing film 7 is formed on the substrate 8 by dry deposition methods such as vacuum deposition or sputtering.

[0124] 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 liquid that does not contain a stabilizer, it is preferable to use an inert gas atmosphere such as dry air or dry nitrogen for coating.

[0125] 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.

[0126] The film thickness can be controlled by changing the pulling speed in the dipping method and the substrate rotation speed in the spin coating method, as well as by changing the concentration of the sol-gel coating solution. Drying can be done at room temperature for about 30 minutes.

[0127] Furthermore, if necessary, drying or heat treatment can be performed at even higher temperatures. 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.

[0128] A suitable film thickness for 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.

[0129] 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 a decomposition process.

[0130] Although some components dissolve, due to differences in the solubility of various hydroxides in hot water, plate-like crystals mainly composed of aluminum oxide precipitate, grow, and form on the surface of the aluminum oxide gel film.

[0131] Furthermore, a metal oxide layer 4 containing an amorphous gel of aluminum oxide, which is the metal oxide layer described above, is formed on the substrate 8. This creates a fine uneven surface 92 for the metal oxide layer 4 and the fine metal oxide 3.

[0132] Furthermore, when 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, similar to the case where an aluminum oxide gel film is used, fine irregularities 92 of fine metal oxide 3 are formed on the surface of the film containing metallic aluminum.

[0133] Therefore, if the substrate 8 is made mainly of aluminum or aluminum oxide, the process of forming 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.

[0134] In the immersion treatment of aluminum oxide gel films to which other compounds besides aluminum oxide components are added, the difference in the solubility of each component in hot water is used to crystallize plate-like aluminum oxide crystals.

[0135] Therefore, unlike the immersion treatment of aluminum oxide gel films 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.

[0136] The height of the fine irregularities 92 of the metal oxide layer 4 and the fine metal oxide 3 can also be adjusted by adjusting the thickness of the aluminum-containing film 7. The average height of the fine irregularities 92 of the metal oxide layer 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 irregularities formed by the plate-like crystals over the aforementioned wide range.

[0137] (Second step: Forming a metal layer 1 on the fine uneven surface 92 of the metal oxide) 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 structure in which the fine uneven surface 92 of the mold 9 is transferred (also called reflected).

[0138] Preferably, the second step includes a step of applying a metal layer 1 onto the fine uneven shape 92 of the metal oxide, then peeling off the substrate and the metal layer 1 present on the fine uneven shape 92 of the metal oxide to form a light-absorbing, heat-shielding film having an uneven structure 2. Alternatively, it is preferable that the second step includes a step of applying a metal layer 1 onto the fine uneven shape 92 of the metal oxide, then peeling off the substrate and the metal layer 1 present on the fine uneven shape 92 of the metal oxide, removing the metal oxide, and forming a light-absorbing, heat-shielding film having an uneven structure 2 of the metal layer 1. Referring to Figure 3C, the step of forming the metal layer 1 on the fine uneven shape 92 of the metal oxide will be described below.

[0139] 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.

[0140] Activation may be performed by immersing the metal oxide with its fine irregular shape 92 together with the substrate 8 in an aqueous solution in which a palladium compound is dissolved. Subsequently, the metal layer 1 is deposited on the metal oxide with its fine irregular shape 92 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 of this embodiment, and an electroless plating solution containing nickel ions, chromium ions, and zinc ions is preferred, while a nickel plating solution containing nickel ions is particularly preferred.

[0141] Nickel plating solutions may contain phosphorus or boron components in addition to nickel. Examples of commercially available nickel plating solutions include the Top Nicolon series from Okuno Pharmaceutical Co., Ltd. The temperature of the plating solution in electroless plating is preferably between 30°C and 98°C, and more preferably between 50°C and 90°C.

[0142] The time required for electroless plating can be adjusted according to the thickness of the metal layer to be formed, and is usually between 30 seconds and 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 (uneven structure 2) on which the fine uneven shape 92 of the metal oxide has been transferred.

[0143] At this time, the portion located above the apex of the convex portion (for example, the convex portion 910) of the fine uneven shape 91 of the metal oxide (on the opposite side from the mold 9) becomes the base portion 11, and the portion located below the apex of the convex portion (for example, the convex portion 910) of the fine uneven shape 91 of the metal oxide (on the side of the mold 9) becomes the fine uneven shape portion (uneven structure 2) (it can also be said that a fine uneven structure of metal exists in the fine uneven shape portion).

[0144] In other words, a metal layer 1 is formed that comprises a base portion 11, a first uneven structure 21 (first structure), and a 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.

[0145] 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.

[0146] It is preferable to perform electroless plating so that the thickness of the metal layer 1 including the uneven structure 2 is between 200 nm and 15,000 nm. The metal layer 1 is formed to cover the vertices of the protrusions (e.g., protrusions 910) of the fine uneven shape 91, and since that portion becomes the base 11, the thickness of the base 11 can be between 200 nm and 15,000 nm.

[0147] Furthermore, the average height of the second uneven structure 22 in the fine uneven shape portion (uneven structure 2) corresponds to the average height of the fine uneven shape 92 of the metal oxide, and is between 100 nm and 1000 nm. When the thickness of the metal layer 1 including the fine uneven shape portion (uneven structure 2) is 200 nm or more, the light-absorbing heat-shielding film of this embodiment exhibits excellent light-absorbing heat-shielding properties.

[0148] After performing the electroless plating treatment described above, electroplating may be performed on the side of the metal layer 1 opposite to the side where the fine uneven surface (uneven structure 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 metal ions such as nickel ions, iron ions, and copper ions can be used.

[0149] When electroplating is performed using the same metal as the metal in metal layer 1, the thickness of the metal layer can be increased by the electroplating process. 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.

[0150] Furthermore, in the electroplating process, the thickness of the metal layer 1 can be adjusted to a desired thickness by controlling the temperature of the electroplating solution, the current density, and the plating time. If necessary, before the electroplating process, the surface of the metal layer 1 opposite to the surface on which the fine uneven shape (uneven structure 2) is provided may be activated with an aqueous solution containing an acid or the like.

[0151] 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 may be included to remove foreign matter from the electroplating solution.

[0152] The second step preferably includes an etching process to remove the fine irregularities of the metal oxide. Examples of etching processes are shown in Figures 3E to 3G. Note that Figure 3D is an inverted version of the light-absorbing heat-shielding film shown in Figure 3C.

[0153] First, in order to obtain the light-absorbing heat-shielding film of this embodiment, the substrate 8 is removed as shown in Figure 3E. The substrate 8 can be removed by peeling with running water. Due to the internal stress within the plating caused by the electroplating process, the substrate 8 and the light-absorbing heat-shielding film naturally separate when treated with running water. The light-absorbing heat-shielding film after the removal of the substrate 8 has a film 7 containing metallic aluminum or a metal oxide layer 4 on its surface.

[0154] If the surface is a film containing metallic aluminum, visible light is reflected by the metallic aluminum, so as shown in Figure 3F, it is necessary to further remove the film containing metallic aluminum by etching.

[0155] Furthermore, if the surface is a metal oxide layer 4 (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.

[0156] As for the etching process, wet etching is preferred, in which the film containing metallic aluminum or the metal oxide layer 4 is dissolved using an acid or alkaline solution. Examples of acids include hydrochloric acid, nitric acid, and sulfuric acid.

[0157] Examples of alkalis include sodium hydroxide and potassium hydroxide. From the viewpoint of work efficiency, etching methods using alkaline solutions are more preferable. 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. The metal layer 1 in which metal oxide is attached to the fine uneven shape (uneven structure 2) has excellent light absorption properties, and the strength of the fine uneven shape (uneven structure 2) can also be improved, resulting in excellent durability and environmental resistance.

[0158] The remaining metal oxides, such as aluminum oxide, after etching (metal oxides adhering to the fine uneven surface (uneven structure 2)) can be detected by EDX or XPS measurements during surface or cross-sectional observation using SEM or TEM.

[0159] 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 film.

[0160] The light-absorbing and heat-shielding film obtained in this embodiment possesses both light-absorbing and heat-shielding properties and abrasion resistance, thus providing an excellent light-absorbing and heat-shielding film.

[0161] The light-absorbing heat-shielding film produced in the first and second steps makes it easier to produce the first uneven structure (first uneven structure 21) with an average roughness Ra1 of 0.1 μm to 5 μm. Furthermore, the average roughness Ra2 of the second uneven structure (second uneven structure 22) becomes 1 nm to 50 nm. With the average roughness Ra1 of the first uneven structure being 0.1 μm to 5 μm, the average emissivity of infrared rays with wavelengths of 8 μm to 14 μm becomes 70% or less. Furthermore, by reducing the average roughness Ra1, the scattering of infrared rays at the surface is suppressed, making it possible to further reduce the average emissivity.

[0162] Furthermore, the average roughness Ra2 of the second uneven structure (second uneven structure 22) is between 1 nm and 50 nm, which results in an average reflectance of 10% or less for visible light with wavelengths between 400 nm and 750 nm.

[0163] (Third step: Step to form a light-absorbing heat-shielding film having multiple through holes from a light-absorbing heat-shielding film) A light-absorbing heat-shielding film having multiple through holes is formed from a light-absorbing heat-shielding film. A light-absorbing heat-shielding film having multiple through holes can be obtained by creating through holes by laser processing the light-absorbing heat-shielding film obtained in the second step.

[0164] When forming a light-absorbing heat-shielding film having multiple through-holes from a light-absorbing heat-shielding film, a light-absorbing heat-shielding film having multiple through-holes may be formed by laminating a first metal sublayer having a group of through-holes having a first average pore diameter obtained in the second step, and a second metal sublayer having a group of through-holes having a second average pore diameter obtained in the second step. Here, the group of through-holes may be a through-hole pattern. The pattern may be a regular pattern or a random pattern.

[0165] Furthermore, since either the uneven surface or the back surface of the light-absorbing heat-shielding film only needs to be 8 μm or less, it can also be formed in a tapered shape. It can also be processed by gradually changing the pore diameter in the film thickness direction.

[0166] <Method for manufacturing a colored heat-shielding member> The method for manufacturing a colored heat-shielding member according to this embodiment includes a step (fourth step) of laminating a colored film onto a main surface different from the main surface having an uneven structure of the light-absorbing heat-shielding film having multiple through holes, which has been manufactured as described above (first to third steps). A colored heat-shielding member is manufactured by overlapping the light-absorbing heat-shielding film having through holes formed above with the colored film.

[0167] When the color space of the target colored heat-shielding material is L*a*b*, the color spaces L*2, a*2, and b*2 of the colored film are determined by the area ratio S of the light-absorbing heat-shielding film. If the color spaces L*1, a*1, and b*1 of the colored heat-shielding film to be used are L*1 = 22.1, a*1 = 3.4, and b*1 = 3.4, then the following relationships hold: L* = (-0.7S + 0.91)L*2 + 5.2S + 11.5 a* = (-0.7S + 0.91)a*2 b* = (-0.7S + 0.91)b*2 Therefore, the color of the colored film that can reproduce the target color may be determined after calculating the area ratio, or the area ratio may be adjusted after determining the color of the colored film.

[0168] For example, if the color of the colored heat-shielding material is to be olive drab, the color space for olive drab will be L* = 46.2, a* = -11.1, and b* = 17.9. If the area ratio S is 0.5, the color spaces L*2, a*2, and b*2 of the colored film are preferably L*2 = 57.3, a*2 = -19.8, and b*2 = 32.0, according to the above calculation formula. However, the above formula is only valid when the color space of the colored heat-shielding film is L*1 = 22.1, a*1 = 3.4, and b*1 = 3.4, and the relationship will be different if the color space is different.

[0169] [Application Examples] <Articles> The articles of this embodiment are equipped with the colored heat-shielding member of this embodiment. The colored heat-shielding member of this embodiment is preferably used for heating elements. Examples of objects on which the colored heat-shielding member equipped with a heating element is installed include air conditioner outdoor units, engines, motors, and transportation equipment equipped with at least one of an engine and a motor.

[0170] Motors include DC motors, AC motors, PM motors, brush motors, stepping motors, induction motors, servo motors, ultrasonic motors, in-wheel motors, and linear motors.

[0171] Transportation equipment equipped with at least one of an engine and a motor includes not only various vehicles such as automobiles, trains, and maglev trains, but also ships, AGVs, and various robots. Transportation equipment may be for freight transport as well as passenger transport, and may be capable of unmanned operation through remote control or autonomous guidance. A hybrid vehicle is a vehicle equipped with a battery, an engine, and a motor.

[0172] In addition, for example, the colored heat-shielding material of this embodiment can be applied as a heat-shielding decorative film to the surface of clothing, vehicle interiors, mobile devices, home appliances, parasols, and tent equipment to create articles according to this embodiment.

[0173] If the coloring or heat dissipation properties deteriorate significantly due to harsh operating conditions, the colored heat shielding material of this embodiment can be easily replaced by peeling off the sheet, as it is in sheet form.

[0174] The following describes embodiments of this disclosure. However, this disclosure is not limited to the embodiments described below.

[0175] The infrared emissivity of the examples was evaluated by measuring the reflectance spectrum in the infrared region. The measuring instrument used was a Fourier transform infrared spectrophotometer (FT / IR-6600, manufactured by JASCO Corporation). The emissivity of the examples was calculated from the reflectance using the relationship between the law of conservation of energy and Kirchhoff's laws. Since the transmittance of the light-absorbing heat-shielding film in the examples is approximately 0%, the emissivity % is the value obtained by subtracting the reflectance % from 100%.

[0176] The reflectance in the visible light region of the examples was evaluated by measuring the reflectance spectrum in the visible light region. The measuring device used was a lens reflectance meter (product name: USPM-RU III, manufactured by Olympus Corporation). Color measurements were performed using a fluorescence spectrophotometer. The measuring instrument used was a Konica Minolta FD-7.

[0177] (Example 1) A substrate 8 made of quartz glass was prepared by forming a surface using a 1000-grit sandpaper. The surface roughness Ra was 164 nm and the standard deviation was 28 nm. A metal oxide film was formed on the surface of this substrate.

[0178] Aluminum sec-butoxide (hereinafter also referred to as "Al(O-sec-Bu)3") and ethyl acetoethyl (hereinafter also referred to as "EtOAcAc") were dissolved in 2-propanol (hereinafter also referred to as "IPA") and stirred at room temperature for about 3 hours to prepare an aluminum oxide sol solution.

[0179] The molar ratio of each component in the aluminum oxide sol solution is Al(O-sec-Bu) ３ The ratio of :EtOAcAc:IPA was 1:1:20. A 0.01 M dilute hydrochloric acid aqueous solution was added to the aluminum oxide sol solution, with the amount of hydrochloric acid added being Al(O-sec-Bu). ３ The mixture was added in a molar ratio of twice the amount of the other component, and refluxed for approximately 6 hours to prepare a sol-gel coating solution.

[0180] A sol-gel coating solution was applied by spin coating to form a coating film. The coating film was then 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 an uneven surface structure.

[0181] An aqueous palladium chloride solution was applied to an aluminum oxide layer having an uneven surface using a spin-coating method, 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 metal layer 1 having an uneven surface and a base 11 beneath it.

[0182] Subsequently, electroplating was performed to further thicken the nickel layer. Next, metal layer 1 was peeled off from the quartz glass substrate, and an etching process was carried out using a 3M sodium hydroxide aqueous solution at room temperature for 50 hours to produce a light-absorbing heat-shielding film. The thickness of the obtained light-absorbing heat-shielding film was approximately 30 μm.

[0183] Figure 4 shows the visible light reflectance of this light-absorbing heat-shielding film. The reflectance was less than 2% at wavelengths from 400 nm to 750 nm, with an average of 1.06%. Furthermore, Figure 5 shows the far-infrared emissivity. The emissivity decreases with increasing wavelength. The average emissivity at wavelengths from 8 μm to 14 μm, which are the detection wavelengths for far-infrared cameras, was 29.6%.

[0184] 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.

[0185] Next, 8 μm holes were formed in the obtained light-absorbing heat-shielding film using a laser micro-hole processing device. The area ratio was set to 0.8. Furthermore, since the thickness of the light-absorbing heat-shielding film was approximately 30 μm and the size of the holes was 8 μm, the T1 / D1 ratio was 0.27.

[0186] Reflectance spectra in the infrared region were measured with a colored film superimposed on a perforated light-absorbing heat-shielding film. The measurement area was defined as a spot area of ​​100 μm x 100 μm. The measurement area contained approximately 40 through-holes.

[0187] A comparison of the reflectance spectra of a non-perforated heat-shielding film with those of a perforated film revealed that there was almost no difference in diameters greater than 10 μm. Furthermore, the formation of perforations smaller than 8 μm had little effect on the emissivity characteristics in the far-infrared region.

[0188] Furthermore, by setting the color space of the colored film to L*2 = 69.5, a*2 = -31.7, and b*2 = 51.3, and laminating it with a light-absorbing, heat-shielding film with through-hole processing, it becomes possible to reproduce a color close to olive drab.

[0189] This disclosure is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of this disclosure. Accordingly, the following claims are attached to make the scope of this disclosure public.

[0190] This application claims priority based on Japanese Patent Application No. 2025-067130 filed on April 15, 2025, and Japanese Patent Application No. 2026-061330 filed on April 2, 2026, and all of the contents of those applications are incorporated herein by reference.

[0191] 1 Metal layer 3 Metal oxide layer 4 Metal oxide layer 21 First uneven structure 22 Second uneven structure 52 Multiple through holes 92 Fine uneven shape S Area ratio 51,100 Light-absorbing heat-shielding film

Claims

1. A light-absorbing heat-shielding film comprising a metal layer having a plurality of through holes, wherein the metal layer has a fine uneven structure in a portion different from the plurality of through holes, the average pore diameter of the plurality of through holes is 400 nm or more and 8 μm or less, the average emissivity of infrared rays with wavelengths of 8 μm or more and 14 μm or less is 70% or less, and the average reflectivity of visible light with wavelengths of 400 nm or more and 750 nm or less is 10% or less.

2. The light-absorbing heat-shielding film according to claim 1, wherein the fine uneven structure has a hierarchical structure consisting of a first uneven structure and a second uneven structure, the second uneven structure is formed on the first uneven structure, 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.

3. The light-absorbing heat-shielding film according to claim 2, wherein 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.

4. The light-absorbing heat-shielding film according to any one of claims 1 to 3, wherein the fine uneven structure has a hierarchical structure consisting of a first uneven structure and a second uneven structure, the second uneven structure is formed on the first uneven structure, the average roughness Ra1 of the first uneven structure is 0.1 μm or more and 1 μm or less, the average roughness Ra2 of the second uneven structure is 1 nm or more and 50 nm or less, the maximum height Rz1 of the first uneven structure is 1 μm or more and 7 μm or less, and the maximum height Rz2 of the second uneven structure is 100 nm or more and 300 nm or less.

5. The light-absorbing heat-shielding film according to any one of claims 1 to 4, wherein the metal layer comprises at least one selected from the group consisting of nickel, chromium, and zinc.

6. The light-absorbing heat-shielding film according to any one of claims 1 to 5, wherein the average pore diameter of the plurality of through holes is 750 nm or more and 8 μm or less.

7. The light-absorbing heat-shielding film according to any one of claims 1 to 6, wherein the relationship between the film thickness D1 of the metal layer and the average pore diameter T1 of the plurality of through holes satisfies the following formula (3): 0.1 ≤ T1 / D1 ≤ 1.6 (3) 8. The light-absorbing heat-shielding film according to any one of claims 1 to 7, wherein the metal layer having a plurality of through holes comprises a laminated structure of a first metal sublayer having a group of through holes having a first average pore diameter and a second metal sublayer having a group of through holes having a second average pore diameter.

9. The light-absorbing heat-shielding film according to claim 8, wherein the first metal sublayer and the second metal sublayer are bonded together.

10. A colored heat-shielding member having a laminated structure of a light-absorbing heat-shielding film and a colored film according to any one of claims 1 to 9, wherein the colored film is laminated on a main surface different from the main surface of the light-absorbing heat-shielding film that has the fine uneven structure.

11. The colored heat-shielding member according to claim 10, wherein the colored heat-shielding member satisfies the following formula (1): 0.1 ≤ S1 / (S1 + S2) ≤ 0.9 (1) (However, in formula (1), when the colored heat-shielding member is viewed from above from the light-absorbing heat-shielding film side, any 100 cm ２ (In this region, let S1 be the area of ​​the light-absorbing heat-shielding film and S2 be the area of ​​the colored film.) 12. The colored heat-shielding member according to claim 10 or 11, wherein the colored heat-shielding member satisfies the following formula (2): 0.3 ≤ S1 / (S1 + S2) ≤ 0.9 (2) (However, in formula (2), when the colored heat-shielding member is viewed from above from the light-absorbing heat-shielding film side, any 100 cm ２ (In this region, let S1 be the area of ​​the light-absorbing heat-shielding film and S2 be the area of ​​the colored film.) 13. The colored heat-shielding member according to any one of claims 10 to 12, wherein the colored film comprises a colored layer and a layer different from the colored layer, and the colored layer is laminated on a main surface different from the main surface of the light-absorbing heat-shielding film on the side with the fine uneven structure.

14. The colored heat-shielding member according to any one of claims 10 to 13, wherein the colored film has a color value of 20 or more in the Lab color space (L*, a*, b*).

15. A method for manufacturing a colored heat shielding member, comprising: a first step of forming a fine uneven shape of a metal oxide; a second step of applying a metal layer onto the fine uneven shape of the metal oxide to form a light-absorbing heat shielding film having a fine uneven structure of metal; a third step of forming a light-absorbing heat shielding film having a plurality of through holes from the light-absorbing heat shielding film; and a fourth step of forming a laminated structure of the light-absorbing heat shielding film having a plurality of through holes and a colored film, wherein the fourth step is a step of laminating the colored film on a main surface of the light-absorbing heat shielding film having a plurality of through holes that is different from the main surface having the fine uneven structure.

16. The method for manufacturing a colored heat-shielding member according to claim 15, wherein the first step includes a step of forming a fine uneven surface of a metal oxide on a substrate.

17. The method for manufacturing a colored heat-shielding member according to claim 15 or 16, wherein the second step includes a step of peeling off the substrate and the metal layer present on the fine uneven surface of the metal oxide after applying the metal layer on the fine uneven surface of the metal oxide to form a light-absorbing heat-shielding film having the fine uneven structure.

18. A method for manufacturing a colored heat-shielding member according to any one of claims 15 to 17, wherein the second step includes, after applying the metal layer on the fine uneven shape of the metal oxide, peeling off the substrate and the metal layer present on the fine uneven shape of the metal oxide, removing the metal oxide, and forming a light-absorbing heat-shielding film having the fine uneven structure of the metal.

19. A method for manufacturing a colored heat-shielding member according to any one of claims 15 to 18, wherein the third step includes a step of forming a light-absorbing heat-shielding film having a plurality of through holes by laminating a first metal sublayer having a group of through holes having a first average pore diameter obtained in the second step and a second metal sublayer having a group of through holes having a second average pore diameter obtained in the second step.

20. A method for manufacturing a colored heat-shielding member according to any one of claims 15 to 19, wherein the light-absorbing heat-shielding film has an average emissivity of 70% or less for infrared rays with a wavelength of 8 μm or more and 14 μm or less, and an average reflectivity of 10% or less for visible light with a wavelength of 400 nm or more and 750 nm or less.

21. A method for manufacturing a colored heat-shielding member according to any one of claims 15 to 20, wherein the first step includes a step of immersing a film containing aluminum in hot water to form a fine uneven shape of the metal oxide.

22. An article comprising a colored heat-shielding member according to any one of claims 10 to 14.

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