Light absorber and method for producing same

Abstract

This light absorber 10 comprises a light absorbing layer 11 made of a resin which contains a light absorbing material. The light absorber is obtained by forming an optical confinement structure 12 in which a plurality of fine protrusions are formed on a surface 11a of the light absorber. The light absorber is configured such that luminous reflectance RSCI according to the Specular Components Included (SCI) method, which detects a total of specular reflected light and diffused / reflected light, does not exceed 0.20%.

Description

[Technical field]

[0001] The present invention relates to a light absorber and a manufacturing method thereof, and more particularly to a light absorber with low reflectance and a manufacturing method thereof. [Background technology]

[0002] A structure has been developed in which a material that absorbs 99.8% or more of visible light, for example, aligned carbon nanotubes, is formed on the surface. Furthermore, a carbon nanotube structure in which a hydrophobic coating is formed on the surface of aligned carbon nanotubes is known (see, for example, Patent Document 1). However, aligned carbon nanotubes are easily destroyed by physical contact and have low contact resistance, so they cannot withstand use in general environments.

[0003] As a light absorber having a relatively high contact resistance, a light absorber made of a resin such as polydimethylsiloxane (PDMS) containing carbon nanotubes or carbon black is known (see, for example, Patent Documents 2 and 3).

[0004] The inventors of the present application have developed a light absorber with low reflectance and have made announcements about it (see Patent Document 4 and Non-Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2017 / 33031 [Patent Document 2] JP 2017-16037 A [Patent Document 3] International Publication No. 2017 / 217504 [Patent Document 4] International Publication No. 2019 / 087439 [Non-patent literature]

[0006] [Non-Patent Document 1] K. Amemiya et al., J. Mater. Chem. C, 2019, 7, pp5418-5425 Summary of the Invention [Problem to be solved by the invention]

[0007] Light absorbers with relatively high contact resistance have a light absorption rate of only about 99.6%, and in terms of reflectance, the difference is two to four times greater than that of oriented carbon nanotube structures. The human eye detects the amount of reflected light to perceive the brightness of an object. According to the Weber-Fechner law, the discrimination threshold of a stimulus is proportional to the intensity of the reference stimulus, so even if the light reflectance of an object is 0.4%, 0.2%, 0.1% or less, the human eye can fully distinguish it. For this reason, even in general environments, in situations where it is desired to suppress unnecessary diffuse reflection, glare, reflection, etc. of light, a light absorption rate of 99.8% or even 99.9% or more has become necessary.

[0008] An object of the present invention is to provide a light absorber having high contact resistance and extremely low luminous reflectance, and a method for producing the same. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a light absorber, comprising a light absorbing layer made of a resin containing a light absorbing material, and a light confinement structure having a plurality of minute protrusions formed on a surface of the light absorber, and the light absorber has a luminous reflectance R SCI is configured to be 0.20% or less.

[0010] According to the above aspect, the light absorber has a light confinement structure in which a plurality of minute protrusions are formed on the surface of a light absorbing layer made of a resin containing a light absorbing material, and thereby the light incident on the light confinement structure from the outside is propagated to the light absorbing layer while suppressing outward reflection, and the light absorbing material contained in the light absorbing layer extremely suppresses outward scattering. As a result, the light reflectance is extremely low, and the luminous reflectance R of the SCI method that detects the sum of the regular reflected light and the diffuse reflected light is extremely low. SCI In addition, by forming the surface of the light absorber from resin, the light absorber has high contact resistance and can be used as an extremely low light reflectance material under general use conditions.

[0011] According to another aspect of the present invention, there is provided a light absorber comprising: another light absorbing layer including a light absorbing material; and a surface layer made of a resin having a light confinement structure on the surface of the other light absorbing layer, the surface layer having a plurality of minute protrusions formed thereon; and the light absorber has a luminous reflectance R SCI is configured to be 0.20% or less.

[0012] According to the above-mentioned other aspect, the light absorber includes a surface layer having a light confinement structure in which a plurality of minute protrusions are formed on a light absorbing layer containing a light absorbing material, and the surface layer suppresses outward reflection of light incident on the light confinement structure from the outside and propagates it to the light absorbing layer, and the light absorbing material contained in the light absorbing layer extremely suppresses outward scattering. As a result, the light reflectance is extremely low, and the luminous reflectance R of the SCI method that detects the sum of the regular reflection light and the diffuse reflection light is very low. SCI In addition, by forming the surface layer of the light absorber from a resin, the light absorber has high contact resistance and can be used as an extremely low light reflectance material under general use conditions.

[0013] According to another aspect of the present invention, there is provided a light absorber having a resin layer containing a light absorbing material and a light confinement structure in which a plurality of minute protrusions are formed on a surface of the resin layer, the light absorbing material including a material selected from the group consisting of black lacquer, inorganic black pigment, oriented carbon nanotubes, and black dye.

[0014] According to another aspect of the present invention, there is provided a light absorber comprising: a first layer containing a light absorbing material selected from the group consisting of black lacquer, inorganic black pigment, oriented carbon nanotubes and black dye, and a resin, or containing a light absorbing material selected from the group consisting of a porous inorganic black film, an electrostatically flocked black cloth and a foamed polyurethane black sheet; and a second layer made of a resin on the first layer, the second layer having a light trapping structure with a plurality of minute protrusions formed on the surface.

[0015] According to another aspect of the present invention, there is provided a method for manufacturing a light absorber, comprising the steps of: forming a precursor of a light absorbing layer from a light absorbing material and a resin liquid; and before the resin liquid hardens, pressing a mold having a plurality of minute protrusions formed on its surface onto the surface of the precursor to harden the resin liquid, thereby forming a light absorbing layer having a light trapping structure on its surface, wherein the light absorbing material comprises a material selected from the group consisting of black lacquer, inorganic black pigment, oriented carbon nanotubes, and black dye.

[0016] According to another aspect of the present invention, there is provided a method for manufacturing a light absorber, the method including the steps of: forming a light absorbing layer containing a light absorbing material selected from the group consisting of black lacquer, inorganic black pigment, oriented carbon nanotubes, and black dye, and a resin, or containing a light absorbing material selected from the group consisting of a porous inorganic black film, an electrostatically flocked black cloth, and a foamed polyurethane black sheet; applying a resin liquid to a surface of the light absorbing layer; and before the resin liquid hardens, pressing a mold having a plurality of minute protrusions formed on its surface to harden the resin liquid, thereby forming a surface layer having a light trapping structure on its surface. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a schematic diagram showing the structure of a light absorber according to the first embodiment. [Diagram 2] 2 is an electron microscope photograph of a surface of an example of a light absorber according to the first embodiment. [Diagram 3] FIG. 4 is a schematic diagram showing a structure of a modified example of the light absorber according to the first embodiment. [Figure 4] 1 is a flowchart showing a method for manufacturing a light absorber according to a first embodiment. [Diagram 5] 1 is a flow chart illustrating a method of forming a mold. [Figure 6] 11 is an electron microscope photograph of the surface of another example of a light absorber. [Figure 7] FIG. 4 is a schematic diagram showing the structure of a light absorber according to a second embodiment. [Figure 8] FIG. 11 is a schematic diagram showing a structure of a modified example of the light absorber according to the second embodiment. [Figure 9] 10 is a flowchart showing a method for manufacturing a light absorber according to a second embodiment. [Figure 10] FIG. 13 is a diagram showing the luminous reflectance of an example. [Figure 11] FIG. 13 is a diagram showing the luminous reflectance of a comparative example. [Figure 12] FIG. 13 is a diagram showing the reflectance of the SCI method in the near infrared in an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that elements common to a plurality of drawings are given the same reference numerals, and detailed descriptions of those elements will be omitted.

[0019] [First embodiment] Fig. 1 is a schematic diagram showing the structure of the light absorber according to the first embodiment. Referring to Fig. 1, the light absorber 10 according to the first embodiment has a light absorbing layer 11, and a light confinement structure 12 is formed on the surface 11a of the light absorbing layer 11. The light absorbing layer 11 is a resin layer containing a light absorbing material. The light absorbing material is a material selected from the group consisting of black lacquer, inorganic black pigment, oriented carbon nanotubes, and black dye. When the light absorbing material is a black dye, it may further contain carbon black.

[0020] The black lacquer is a black natural or synthetic lacquer. The light absorbing layer 11, which is a black lacquer coating film containing black lacquer, is a coating film obtained by drying and curing a black refined lacquer paint in the air, or a coating film obtained by drying and curing a black cashew paint (for example, manufactured by Cashew Co., Ltd.) in the air. The light absorber 10 is formed by forming a light trapping structure 12 on the surface of this coating film before the coating film is cured.

[0021] The inorganic black pigment is a fine particle of a metal, a metal oxide, or a composite thereof, such as fine particles of aluminum, aluminum oxide, platinum, gold, silver, or a mixture thereof. The inorganic black pigment is, for example, a component of Metal Velvet by Acktar. The light absorber 10 is formed by kneading the inorganic black pigment into a resin to form a light absorbing layer 11, and forming a light trapping structure 12 on the surface of the light absorbing layer 11 before the resin is cured.

[0022] The oriented carbon nanotube is a material having a layer made of a large number of carbon nanotubes aligned perpendicularly to a substrate. The oriented carbon nanotube is, for example, a material described in International Publication No. 2017 / 033031. The light absorber 10 is formed by embedding the oriented carbon nanotubes in a resin to form a light absorbing layer 11 as an oriented carbon nanotube-embedded resin layer, and forming a light trapping structure 12 on the surface of the resin before the resin is cured.

[0023] The black dye may be, for example, aniline black, nigrosine, or sudan black, or an oil-based paint or oil-based coating material containing aniline black may be used. The light absorber 10 is formed by kneading a black dye and a resin and applying the mixture, or by applying and curing a paint or coating material to form a light absorbing layer 11, which is a black dye-containing resin layer, and forming a light trapping structure 12 on the surface of the light absorbing layer 11 before the resin is cured.

[0024] The light absorbing layer 11 can be made of at least one resin selected from the group consisting of epoxy resin, polyester resin, acrylic resin, polycarbonate resin, and vinyl chloride resin. The light absorbing layer 11 is formed by curing such a resin, so that the light confinement structure formed on the surface can have improved contact resistance, and the light confinement structure is less likely to deteriorate even when touched by hand, and an increase in light reflectance is suppressed. The light absorbing layer 11 may be made of an ultraviolet-curable resin, which is preferable in that the curing time can be shortened.

[0025] The light confinement structure 12 is composed of many tiny protrusions formed on the surface 11a of the light absorbing layer 11. The light confinement structure 12 captures light incident from the outside to the base of the protrusions and further into the light absorbing layer 11. Specifically, the light confinement structure 12 has a plurality of protrusions formed to protrude outward from the surface. The protrusions have a tip end that is connected in a ridge-like shape or a cone-like shape. They have a cross-sectional shape that gradually widens from the tip end to the base end. When the tip end is connected in a ridge-like shape, it is preferable that adjacent ridges are 0.1 μm to 100 μm apart. When the tip end is cone-shaped, it is preferable that the distance between adjacent tips is 0.1 μm to 100 μm.

[0026] FIG. 2 is an electron microscope photograph of the surface of an example of the light absorber according to the first embodiment, showing an example of the light confinement structure. Referring to FIG. 2 together with FIG. 1, the light confinement structure 12 has a number of protrusions formed on the surface 11a of the light absorbing layer 11 in a ridge shape, with the base gradually expanding. It can be seen that adjacent ridges are formed with a distance of 1 μm to several tens of μm. The light incident by the light confinement structure 12 propagates in the direction of the base of the protrusion, and scattering is suppressed and absorbed by the light absorbing material of the light absorbing layer 11. Since scattering is suppressed in the light absorbing layer 11, light propagating outward from the surface 11a of the light absorber 11 is suppressed. In this way, the light absorber 10 can have an extremely low reflectance, in particular, a very low luminous reflectance, which is a reflectance value weighted and averaged by the sensitivity of the human eye (spectral luminous efficiency). The light confinement structure of the light absorber according to the second embodiment described later is also the same as FIG. 2.

[0027] As described above, the light absorbing layer 11 of the light absorber 10 is a resin composite material containing a light absorbing material with extremely low light scattering properties. The light absorbing layer 11 can be characterized by its low light scattering properties by mirror-finishing the light confinement structure 12 on the surface 11a of the light absorbing layer 11. The light absorbing layer 11 has a luminous reflectance R SCE It is preferable that the content of the Cr content is 0.20% or less.

[0028] Due to the mirror finish, the light absorber 10 has a luminous reflectance R SCI The luminous reflectance R of the SCE method SCE Ratio of R SCE / R SCI The surface of the light absorbing layer 11 is processed so that the luminous reflectance R SCI On the other hand, the luminous reflectance R, which does not include specular reflection and only detects diffuse reflection, SCEThe proportion of

[0029] As a method for mirror finishing, for example, the surface on which the light confinement structure 12 is formed may be filled with a transparent resin liquid to form a microscopic flat surface, or the light confinement structure 12 may be flattened by a process such as polishing or dissolving. Also, as a method for mirror finishing, the surface on which the light confinement structure is to be formed may be formed flat, or a transparent resin liquid may be applied to form the surface flat.

[0030] As will be apparent from the examples, the light absorber 10 has a luminous reflectance R SCI Furthermore, depending on the light absorbing material of the light absorbing layer 11, the luminous reflectance R SCI It is preferable to configure the light confinement structure 12 so that a light scattering coefficient of 0.10% or less can be obtained as a light scattering coefficient. This can be obtained by the light confinement structure 12 and the light absorbing layer 11 with extremely low light scattering properties.

[0031] SCI method visual reflectance R SCI and the luminous reflectance R of the SCE method SCE The measurement is performed using an integrating sphere spectrophotometer (Konica Minolta, Model CM-600d) with the following geometric conditions c of JIS Z 8722: di: 8° for SCI method (including specular reflected light (specular reflected light)), de: 8° for SCE method (excluding specular reflected light (specular reflected light)), field of view: 10°, light source: D65, integrating sphere: diameter 40 mm, measurement wavelength range: 400 nm to 700 nm, measurement wavelength interval: 10 nm, measurement diameter: diameter 8 mm, illumination diameter: diameter 11 mm. The luminous reflectance corresponds to Y when the reflected object color is expressed in the XYZ color system (CIE1931 (standard) color system).

[0032] Fig. 3 is a schematic diagram showing the structure of a modified example of the light absorber according to the first embodiment. Referring to Fig. 3, as a modified example, the light absorber 20 further has a lower light absorbing layer 23 containing a light absorbing material below the light absorbing layer 11. The light absorber 20 has the lower light absorbing layer 23 and the light absorbing layer 11 thereon, and a light confinement structure 12 is formed on the surface 11a of the light absorbing layer 11. With this structure, even if there is light in a wavelength band that transmits through the light absorbing layer 11, the light is absorbed by the light absorbing material contained in the lower light absorbing layer 23, thereby reducing the reflectance of the light absorber 20.

[0033] The light absorbing material of the lower light absorbing layer 23 is not particularly limited, and it is preferable to use a light absorbing material different from that used in the light absorbing layer 11 among the light absorbing materials of the light absorbing layer 11. The resin of the lower light absorbing layer 23 is not particularly limited, and the resin of the light absorbing layer 11 can be used.

[0034] In the case where the light absorbing material of the light absorbing layer 11 is black lacquer or black dye, for example, the lower light absorbing layer 23 is preferably a porous inorganic black film or a resin layer containing carbon black. The porous inorganic black film is a porous metal, metal oxide, or a composite thereof, such as Metal Velvet by Acktar.

[0035] A plurality of layers may be provided as the lower light absorbing layer 23. The lower light absorbing layer 23 may be formed by stacking a combination of layers having absorption characteristics for different wavelengths.

[0036] 4 is a flowchart showing a method for manufacturing the light absorber according to the first embodiment. With reference to FIG. 4, the method for manufacturing the light absorber according to this embodiment will be described.

[0037] First, a precursor of the light absorbing layer is formed from a light absorbing material and a resin liquid (S100). The resin liquid contains the light absorbing material and a resin, and depending on the resin material, it may contain a solvent. If the light absorbing material is black lacquer, a black lacquer paint is applied. If the light absorbing material is oriented carbon nanotubes, the surface is applied with a resin liquid or immersed in the resin liquid. If the light absorbing material is an inorganic black pigment or black dye, it may be mixed with the resin liquid and applied to the substrate.

[0038] Next, before the resin liquid hardens, a mold having a plurality of minute protrusions formed on its surface is pressed onto the surface of the precursor to harden the resin liquid, forming a light absorbing layer 11 having a light confinement structure on its surface (S110). A plurality of minute protrusions are formed on the surface of the mold, which are transferred to the surface of the precursor of the light absorbing layer by pressing to form a light confinement structure. The resin liquid is preferably an ultraviolet curable resin, and the mold is preferably a material that transmits ultraviolet light. This allows the precursor of the light absorbing layer to harden in a short time. The mold is formed, for example, as follows.

[0039] 5 is a flow chart showing a method for forming a mold. The method for forming a mold will be described with reference to FIG.

[0040] First, an ion beam is irradiated onto a resin substrate (S200). Specifically, an ion beam accelerated by a cyclotron is irradiated onto a resin substrate, for example, an allyl diglycol carbonate resin (CR-39). This forms a large number of ion tracks near the surface of the resin substrate. It is preferable that the ion tracks are randomly distributed. Although oxygen ions can be used as the ion beam, it is preferable that the ion beam is either Ne ions or ions heavier than Ne ions, since this makes it easier for etching to proceed selectively along the ion tracks in the resin substrate, and the final pit aspect ratio (pit depth / pit radius) can be increased.

[0041] The acceleration energy of the ion beam is preferably 200 MeV or more, since it is possible to obtain a sufficient penetration depth and a large pit aspect ratio even if the pit radius is large. The irradiation density of the ion beam onto the resin substrate is appropriately selected, but from the viewpoint of a necessary and sufficient pit density for capturing light of far-infrared wavelengths, it is preferable to set the irradiation density to 1×10 5 / cm 2 ~1×10 6 / cm 2 It is preferable that:

[0042] Next, the resin substrate irradiated with the ion beam is etched with an alkaline solution to form an uneven surface on the surface (S210). Specifically, the alkaline solution is an aqueous solution of sodium hydroxide or potassium hydroxide, and the resin substrate irradiated with the ion beam is immersed in the alkaline solution for a predetermined time while being heated to, for example, 70° C. Then, the resin substrate is washed with water and dried.

[0043] Next, a resin liquid is applied to cover the uneven surface of the etched resin substrate and cured to form a mold (S220). This forms the mold. A surface of the mold has an uneven surface that is an inverse of the uneven surface formed in S210. The mold is formed, for example, from a gas-permeable elastomer material, a metal film, and a photocurable resin. In the step of forming the light absorbing layer (S110 in FIG. 4), it is preferable to use a gas-permeable elastomer material, for example, PDMS, for the mold, since this makes it easy to degas any air bubbles that exist between the resin liquid coating and the mold.

[0044] Specifically, the uneven surface of the mold has a plurality of protrusions formed to protrude outward from the surface. The protrusions have a tip that is connected in a ridge-like shape or a cone-like shape. They have a cross-sectional shape that gradually widens from the tip to the base. When the tip is connected in a ridge-like shape, the distance between adjacent ridges is preferably 0.1 μm to 100 μm. When the tip is cone-shaped, the distance between adjacent tips is preferably 0.1 μm to 100 μm.

[0045] When the light trapping structure 12 is formed using the mold formed in S220, an uneven surface is formed in which the tips of the projections are connected in a ridge-like manner, as shown in the electron microscope photograph of FIG.

[0046] The mold may be a resin plate formed by applying and transferring a resin liquid onto the uneven surface of the mold formed in S220. Alternatively, the mold may be a resin substrate having an uneven surface formed in S210. When the light confinement structure 12 is formed using such a mold, an uneven surface is formed in which the tips of the protrusions have a conical shape. An example of the light confinement structure 12 is shown in FIG.

[0047] Fig. 6 is an electron microscope photograph of the surface of another example of a light absorber, showing another example of a light trapping structure. Referring to Fig. 6, it can be seen that the light trapping structure has a plurality of protrusions, the tips of which are conical, and have a cross-sectional shape that gradually widens from the tip to the base, with adjacent conical tips being formed at an interval of 1 µm to several tens of µm.

[0048] According to this embodiment, the light absorber 10 has a light confinement structure 12 on the surface of a very low scattering light absorbing layer 11. The light absorber 10 suppresses outward reflection of light incident on the light confinement structure 12 from the outside and propagates the light to the light absorbing layer 11, and the light absorbing material contained in the light absorbing layer 11 highly suppresses outward scattering, resulting in an extremely low reflectance. In addition, the light absorber 10 can improve contact resistance by forming the surface from a resin, and can be used as an extremely low light reflectance material under general usage conditions.

[0049] [Second embodiment] Fig. 7 is a schematic diagram showing the structure of a light absorber according to the second embodiment. Referring to Fig. 7, a light absorber 30 according to the second embodiment has a light absorbing layer 31 and a surface layer 32 thereon, and a light confinement structure 12 is formed on a surface 32a of the surface layer 32. The light confinement structure 12 is the same as that of the first embodiment.

[0050] The light absorbing layer 31 is a layer containing a light absorbing material and a resin similar to the light absorbing layer 11 of the first embodiment, and a black lacquer coating film, an oriented carbon nanotube embedded resin layer, and a black dye-containing resin layer can be used. The light absorbing layer 31 may contain a light absorbing material selected from the group consisting of a porous inorganic black film, an electrostatic flocked black cloth, and a foamed polyurethane black sheet. It is also possible to form the light absorbing layer 31 by combining these light absorbing materials.

[0051] The porous inorganic black film is a porous metal, a metal oxide, or a composite thereof, such as Metal Velvet by Acktar Co., Ltd. The light absorber 30 has a surface layer 32 in which the porous inorganic black film is used as a light absorbing layer 31 and is embedded in a resin to form a light trapping structure 12 on the surface thereof.

[0052] The electrostatic flocked black cloth is a sheet-like material with black nap formed on the surface (for example, manufactured by Belle Sade, product name: Ronsade S0.5). The light absorber 30 prevents deterioration of light trapping properties due to dust and dirt by forming a surface layer 32 made of resin on the surface of the electrostatic flocked black cloth, and furthermore, the light trapping structure 12 provides extremely low light reflectivity.

[0053] The foamed polyurethane black sheet is a porous sheet made of polyurethane resin containing carbon black powder. The light absorber 30 has a surface layer 32 having a light trapping structure 12 made of resin formed on the surface of the foamed polyurethane black sheet, thereby enhancing the light trapping property and achieving extremely low light reflectivity.

[0054] The surface layer 32 is made of at least one resin selected from the group consisting of ultraviolet curing resin, epoxy resin, polyester resin, acrylic resin, polycarbonate resin, and vinyl chloride resin. Since the surface layer 32 is made of such a resin, the light confinement structure 12 formed on the surface can have improved contact resistance, and the light confinement structure 12 is less likely to deteriorate even when touched with a hand, and an increase in light reflectance is suppressed.

[0055] The surface layer 32 has light-transmitting properties and may be transparent. The surface layer 32 transmits light propagating from the light confinement structure 12 formed on its surface 32a, and the light propagates to the light absorption layer 31. That is, the surface layer 32 suppresses scattering of light and suppresses light propagating outward.

[0056] The surface layer 32 may contain a black dye, which has excellent light absorption and low scattering properties and can therefore reduce the reflectance.

[0057] As described above, the light absorbing layer 31 of the light absorber 30 contains a light absorbing material with low light scattering properties. By mirror-finishing the light confinement structure 12 of the surface layer 32, the light absorbing layer 31 of the light absorber 30 can be characterized by low light scattering properties. As in the first embodiment, the light absorbing layer 31 has a luminous reflectance R SCE It is preferable that the light absorber 30 is configured so that the luminous reflectance R SCI The luminous reflectance R of the SCE method SCE Ratio of R SCE / R SCI The surface of the surface layer 32 is processed so that the difference between the thickness of the surface and the thickness of the light confinement structure 12 is 0.05 or less. As a method for mirror finishing, for example, the surface layer 32 on which the light confinement structure 12 is formed may be filled with a transparent resin liquid to form a microscopically flat surface, or the light confinement structure 12 may be flattened by polishing, dissolving, or the like. As a method for mirror finishing, the surface layer 32 may be formed flat without forming a light confinement structure thereon.

[0058] FIG. 8 is a schematic diagram showing the structure of a modified example of the light absorber according to the second embodiment. Referring to FIG. 8, as a modified example, the light absorber 40 has a lower light absorbing layer 43 containing a light absorbing material under the light absorbing layer 31. The light absorbing material of the lower light absorbing layer 43 is not particularly limited, and it is preferable to use a light absorbing material different from that used for the light absorbing layer 31 among the light absorbing materials of the light absorbing layer 31. When the light absorbing material of the light absorbing layer 31 is black lacquer, oriented carbon nanotubes, or black dye, it is preferable that the light absorbing material of the lower light absorbing layer 43 is a porous inorganic black film or a resin layer containing carbon black. The resin of the lower light absorbing layer 43 is not particularly limited, and the same resin as that of the light absorbing layer 31 can be used. The light absorber 40 has a lower light absorbing layer 43, a light absorbing layer 31 thereon, and a surface layer 32 thereon, and a light confinement structure 12 is formed on the surface of the surface layer 32 at 32a. With this structure, even if there is light in a wavelength band that transmits through the light absorbing layer 31, the light is absorbed by the light absorbing material contained in the lower light absorbing layer 43, thereby reducing the reflectance of the light absorber 40. The lower light absorbing layer 43 may be formed from the same material as the lower light absorbing layer 23 in the first embodiment. Note that the lower light absorbing layer 43 may be provided in multiple layers. The lower light absorbing layer 43 may be laminated by combining layers having absorption characteristics for different wavelengths.

[0059] 9 is a flowchart showing a method for manufacturing a light absorber according to the second embodiment. With reference to FIG. 9, the method for manufacturing a light absorber according to this embodiment will be described.

[0060] First, a light absorbing layer containing a light absorbing material is formed (S300). A resin layer containing the same light absorbing material as the light absorbing layer 11 of the first embodiment is prepared by forming a precursor of the light absorbing layer in the same manner as in S100, and then curing the resin liquid to form the light absorbing layer 31. Alternatively, the above-mentioned porous inorganic black film, electrostatic flocked black cloth, and foamed polyurethane black sheet are themselves used as the light absorbing layer 31.

[0061] Next, a resin liquid is applied to the surface of the light absorbing layer to form a precursor of the surface layer (S310). Specifically, a resin liquid containing a resin and, depending on the resin material, a solvent is applied to the surface of the light absorbing layer 31. The resin may be the resin used in S100, or may be a UV-curable resin. The resin may be transparent or may contain a black dye. The UV-curable resin is preferable because it can be cured in a short time by UV irradiation.

[0062] Next, before the resin liquid hardens, a mold with a plurality of minute protrusions formed on its surface is pressed to harden the resin liquid, thereby forming a surface layer having a light confinement structure on its surface (S320). The mold is the same as the mold in the first embodiment. The mold has a plurality of minute protrusions formed thereon, which are transferred to the surface of the precursor of the surface layer by pressing, forming a surface layer 32 having the light confinement structure 12. When the resin liquid is an ultraviolet curable resin, the mold is preferably made of a material that transmits ultraviolet light. This allows the precursor of the surface layer 32 to harden in a short time.

[0063] According to this embodiment, the light absorber 30 has a surface layer 32 in which a light confinement structure 12 is formed on the surface of a light absorbing layer 31 having low scattering properties. According to the study by the present inventor, it has been found that by forming the surface layer 32 on the light absorbing layer 31, the light scattering can be significantly reduced compared to the light absorbing layer 31 alone. In the light absorber 30, the surface layer 32 suppresses outward reflection of light incident from the outside by the light confinement structure 12 and propagates it to the light absorbing layer 31, and the light absorbing material contained in the light absorbing layer 31 significantly suppresses outward scattering, resulting in an extremely low reflectance. In addition, by forming the surface layer 32 from a resin, it is possible to improve contact resistance, and the light absorber 30 can be used as an extremely low light reflectance material under general use conditions.

[0064] [Example 1] The light absorber of Example 1 is an example of the light absorber of the first embodiment. The light absorbing layer 11 is a black lacquer coating film. A black lacquer paint (synthetic lacquer paint) liquid (manufactured by Sanko Shoji Co., Ltd., product name: Urashima brand high-quality lacquer, black) was applied to a flat polydimethylsiloxane (PDMS) sheet to form a thickness of 0.3 mm, and before the black lacquer paint liquid hardened, it was embossed using a polydimethylsiloxane (PDMS) mold formed according to FIG. 5 and its explanation, and the black lacquer paint liquid was hardened to form a light absorber having a light trapping structure 12. The mirror-finished sample was prepared by applying and filling a transparent acrylic resin-based ultraviolet curing resin liquid (manufactured by Padico Co., Ltd., product name: UV-LED Resin Hoshi no Shizuku Hard) to the light trapping structure 12, irradiating it with ultraviolet light (ultraviolet lamp (manufactured by Elber Co., Ltd., product name LED & UV LAMP), 6 W, irradiation time: 3 minutes), hardening it, and flattening the surface.

[0065] [Example 2] The light absorber of Example 2 is an example of a light absorber of a modified example of the first embodiment. A porous inorganic black film (manufactured by Acktar, product name: Metal Velvet) was used as the lower light absorbing layer 23. A black lacquer paint (synthetic lacquer paint) liquid (manufactured by Toho Sangyo, product name: Special Urushi, Black) was applied thereon as the light absorbing layer 11 to a thickness of 0.3 mm. Before the black lacquer paint liquid hardened, it was embossed using a polydimethylsiloxane (PDMS) mold formed according to FIG. 5 and its description, and the black lacquer paint liquid was hardened to form a light absorber having a light trapping structure. A mirror-finished sample was used that did not form a light trapping structure on the surface of the light absorbing layer 11.

[0066] [Example 3] The light absorber of Example 3 is an example of a light absorber of a modified example of the first embodiment. As the lower light absorbing layer 23, a resin layer containing carbon black was formed by applying acrylic gouache paint (Turner Color Co., Ltd., product name: Acrylic Gouache Regular Color Lamp Black (PBk7)) to a PET (polyethylene terephthalate) sheet and drying it. A black lacquer paint liquid similar to that of Example 2 was applied thereon to form the light absorbing layer 11, and a light trapping structure was formed. For the mirror-finished sample, a light trapping structure was not formed on the surface of the light absorbing layer 11.

[0067] [Example 4] The light absorber of Example 4 is an example of the light absorber of the second embodiment. The light absorbing layer 31 was formed by forming a black lacquer coating liquid similar to that of Example 1 as a light absorbing material to a thickness of 0.3 mm and curing it. On top of that, as the surface layer 32, a transparent acrylic resin-based ultraviolet curing resin liquid (manufactured by Padico, product name: UV-LED Resin Hoshi no Shizuku Soft) was applied to the surface of the light absorbing layer 31 to form a thickness of 0.3 mm, and a light absorber having a light trapping structure was formed by pressing using a mold similar to that of Example 1 and irradiating ultraviolet rays from the back side of the mold (ultraviolet lamp (manufactured by Elber, product name LED & UV LAMP), 6 W, irradiation time: 3 minutes). For the mirror-finished sample, a light trapping structure was not formed on the surface of the surface layer 32.

[0068] [Comparative Example 1] The light absorber of Comparative Example 1 was the light absorbing layer 31 of Example 4 alone, and the surface layer 32 was not formed.

[0069] [Example 5] The light absorber of Example 5 is an example of a light absorber of a modified example of the second embodiment. As the lower light absorbing layer 43, a PET sheet was coated with acrylic gouache lamp black paint (Turner Color Co., Ltd., product name: acrylic gouache normal color lamp black (PBk7)) as a resin layer containing carbon black, and dried. On top of that, the same black lacquer paint as in Example 2 was coated as the light absorbing layer 31 to form a thickness of 0.3 mm. After the black lacquer paint liquid was cured, the surface layer 32 was formed in the same manner as in Example 4. For the mirror-finished sample, one that did not form a light trapping structure on the surface of the surface layer 32 was used.

[0070] [Example 6] The light absorber of Example 6 is an example of the light absorber of the second embodiment. The light absorption layer 31 was prepared by dropping the same ultraviolet curing resin liquid as in Example 4 onto an oriented carbon nanotube (manufactured by Microphase, product name: VACNT-SS, a carbon nanotube with a length of 5 μm vertically grown on a Ni substrate) as a light absorption material, and curing it by irradiating ultraviolet light (ultraviolet lamp (manufactured by Elber, product name LED & UV LAMP), 6 W, irradiation time: 3 minutes) after vacuum degassing, and peeling it off from the Ni substrate to obtain the light absorption layer 31. On top of that, a transparent acrylate resin-based ultraviolet curing resin liquid (manufactured by Kiyohara, product name: LED & UV craft resin liquid) was applied as a surface layer 32 to form a thickness of 0.3 mm, and a mold similar to that of Example 1 was used for stamping, and ultraviolet light was irradiated from the back side of the mold to form a light absorber having a light trapping structure. The light absorption layer 31 alone was used as a mirror-finished sample.

[0071] [Comparative Example 2] The light absorber of Comparative Example 2 is the aligned carbon nanotube of Example 6 alone.

[0072] [Example 7] The light absorber of Example 7 is an example of the light absorber of the second embodiment. A porous inorganic black film (manufactured by Acktar, product name: Metal Velvet) was used as the light absorbing layer 31. A surface layer 32 similar to that of Example 4 was formed thereon. The mirror-finished sample used did not have a light trapping structure formed on the surface of the surface layer 32.

[0073] [Comparative Example 3] The light absorber of Comparative Example 3 was the porous inorganic black film of Example 7 alone.

[0074] [Example 8] The light absorber of Example 8 is an example of the light absorber of the second embodiment. The light absorbing layer 31 is a resin layer containing a black dye, and is formed by applying an acrylic gouache jet black paint (Turner Color Co., Ltd., product name: acrylic gouache ordinary color jet black (PBk1)) to a PET sheet and drying it. A surface layer 32 similar to that of Example 4 was formed thereon. A mirror-finished sample was used that did not have a light trapping structure on the surface of the surface layer 32.

[0075] [Comparative Example 4] The light absorber of Comparative Example 4 was the light absorbing layer 31 of Example 8, and the surface layer 32 was not formed.

[0076] [Example 9] The light absorber of Example 9 is an example of the light absorber of the second embodiment. The light absorbing layer 31 is a resin layer containing a black dye and carbon black, and is made by mixing an acrylic gouache jet black paint (Turner Color Co., Ltd., product name: acrylic gouache ordinary color jet black (PBk1)) and an acrylic gouache lamp black paint (Turner Color Co., Ltd., product name: acrylic gouache ordinary color lamp black (PBk7)) in a weight ratio of 5:1, applying the mixture to a PET sheet and drying. A surface layer 32 similar to that of Example 4 was formed thereon. A mirror-finished sample was used that did not have a light trapping structure formed on the surface of the surface layer 32.

[0077] [Example 10] The light absorber of Example 10 is an example of the light absorber of the second embodiment. The light absorbing layer 31 is made of the same material as that of Example 9, and is made by mixing acrylic gouache jet black and lamp black in a weight ratio of 2.5:1, applying the mixture to a PET sheet and drying it. A surface layer 32 similar to that of Example 4 is formed thereon. The mirror-finished sample used does not have a light trapping structure on the surface of the surface layer 32.

[0078] [Comparative Example 5] In the light absorber of Comparative Example 5, the lamp black used in Examples 9 and 10 was applied to a PET sheet in a thickness of 0.2 mm as a light absorbing layer, and the surface layer 32 was not formed.

[0079] [Example 11] The light absorber of Example 11 is an example of a light absorber of a modified example of the first embodiment, and as the lower light absorbing layer 23, as a resin layer containing carbon black, acrylic gouache paint (Turner Color Co., Ltd., product name: Acrylic Gouache Ordinary Color Lamp Black (PBk7)) was applied to a PET sheet and dried. On top of that, as the light absorbing layer 11 containing a black dye, black dye (Holbein Paints, product name: Expert Pigment #30 PG143 Diamond Black (condensed aniline) 2% by weight) was kneaded with a two-liquid epoxy resin (Nissin Resin Co., Ltd., product name: Crystal Resin) and applied, and the mold was pressed and cured using the same mold as in Example 1. The mirror-finished sample used did not form a light trapping structure on the surface of the light absorbing layer 11.

[0080] [Example 12] The light absorber of Example 12 is an example of the light absorber of the second embodiment. The light absorbing layer 31 was made of electrostatically flocked black cloth (manufactured by Velshade, product name: electrostatic flocked sheet Ronsade S, thickness 0.50 mm). A surface layer 32 similar to that of Example 4 was formed thereon. The mirror-finished sample used was one in which no light trapping structure was formed on the surface of the surface layer 32.

[0081] [Comparative Example 6] The light absorber of Comparative Example 6 was the electrostatic flocked black cloth of Example 12 alone, and the surface layer 32 was not formed.

[0082] [Example 13] The light absorber of Example 13 is an example of the light absorber of the second embodiment. The light absorbing layer 31 was a foamed polyurethane type black sheet containing carbon black (manufactured by Systems Engineering Co., Ltd., product name: light shielding / absorbing sheet Super Black IR). A surface layer 32 similar to that of Example 4 was formed thereon. A mirror-finished sample was used in which no light trapping structure was formed on the surface of the surface layer 32.

[0083] [Comparative Example 7] The light absorber of Comparative Example 7 was the polyurethane foam type black sheet of Example 13 alone, and the surface layer 32 was not formed.

[0084] [Comparative Example 8] The light absorber of Comparative Example 8 has a light trapping structure formed on the surface, and the light absorbing layer is formed of silicone rubber containing carbon black as a light absorbing material. An electrode layer for electroplating, which is a Ti film having a thickness of 50 nm and a Cu film having a thickness of 300 nm, was formed by a sputtering method on CR-39 on which an uneven surface was formed in S210 of FIG. 5. Then, a Ni plating film having a thickness of 500 μm was formed as a transfer body on the electrode layer by an electroplating method. Then, the Ni plating film was peeled off from the resin substrate to obtain a Ni plating film with the unevenness transferred thereto. Next, the main agent and the curing agent of a two-liquid curing silicone composition (main agent SIM-360 and curing agent CAT-360, both manufactured by Shin-Etsu Silicone Co., Ltd.) were mixed at a ratio of 9:1, and further, 5 wt% of carbon black was kneaded with respect to the silicone composition, and after degassing, the silicone rubber was applied dropwise to the uneven surface of the Ni plating film to cover the surface, and further degassed in a vacuum desiccator, and then left at room temperature for 12 hours to obtain a cured silicone rubber. Next, the cured silicone rubber was peeled off from the Ni plating film to obtain a light absorber of carbon black-containing silicone rubber of Comparative Example 8 to which the irregularities were transferred.

[0085] FIG. 10 shows the luminous reflectance R SCI 1 is a graph showing the luminous reflectance R of a mirror-finished sample. SCE , R SCI and R SCE / R SCI FIG. 11 shows the luminous reflectance R SCI FIG.

[0086] 10 and 11, in Examples 1 to 13, the luminous reflectance R SCI is 0.02% to 0.17%, and the luminous reflectance R is extremely low at 0.20% or less. SCI It can be seen that the light absorbers have the following characteristics. Comparative Examples 3, 4, 6, and 7, which are conventional commercially available light absorbers, have a luminous reflectance R SCIThe luminous reflectance R SCI Moreover, it can be seen that the light absorber has a luminous reflectance R SCI It can be seen that the

[0087] In particular, in Examples 1 to 8 and Example 11, the luminous reflectance R SCI It can be seen that the luminous reflectance is 0.10% or less. The light absorbing materials of the light absorbing layers 11 and 31 in Examples 1 to 8 and Example 11 are black synthetic lacquer, oriented carbon nanotubes, inorganic black pigments, or black dyes. These light absorbing materials are preferable in that they can reduce the luminous reflectance to an extremely low level of 0.10% or less.

[0088] The luminous reflectance R of the mirror-finished samples of Examples 1 to 13, i.e., the light absorber without a light trapping structure, measured using the SCE method for detecting diffuse reflected light. SCE From this, it can be seen that in Examples 1 to 13, a light absorbing layer with extremely low light scattering properties is combined with a light trapping structure to achieve an extremely low luminous reflectance R SCI It can be seen that the above equation was obtained.

[0089] Example 4 shows the luminous reflectance R SCI is 0.07%, while it is 4.90% in Comparative Example 1, and it is found that the surface layer 32 having the light confinement structure in Example 4 has improved low reflectivity.

[0090] Example 6 shows the luminous reflectance R SCI is 0.07%, while it is almost the same at 0.06% in Comparative Example 2. Since Comparative Example 2 has aligned carbon nanotubes arranged on the surface, while Example 6 has surface layer 32 formed of resin, Example 6 has higher contact resistance than Comparative Example 2.

[0091] Example 7 shows the luminous reflectance R SCIis 0.06%, while it is 0.86% in Comparative Example 3, which shows that the surface layer 32 having the light confinement structure of Example 7 improves low reflectivity. Moreover, Example 7 has higher contact resistance than Comparative Example 3 due to the surface layer 32.

[0092] Example 8 shows the luminous reflectance R SCI The reflectance of the surface layer 32 having the light confinement structure of Example 8 is 0.08%, whereas that of Comparative Example 4 is 1.36%, which shows that the surface layer 32 having the light confinement structure of Example 8 improves the low reflectance. Moreover, Example 8 has a higher contact resistance than Comparative Example 4 due to the surface layer 32.

[0093] Examples 9 and 10 show a luminous reflectance R SCI are 0.12% and 0.17%, respectively, while it is 2.47% in Comparative Example 5, which shows that the surface layer 32 having the light confinement structure of Examples 9 and 10 improves low reflectivity. Moreover, Examples 9 and 10 have higher contact resistance than Comparative Example 5 due to the surface layer 32.

[0094] Example 12 shows the luminous reflectance R SCI is 0.11%, while it is 0.56% in Comparative Example 6, and it is found that the surface layer 32 having the light confinement structure in Example 12 has improved low reflectivity.

[0095] Example 13 shows the luminous reflectance R SCI is 0.17%, while it is 1.22% in Comparative Example 7, and it is found that the surface layer 32 having the light confinement structure in Example 13 has improved low reflectivity.

[0096] FIG. 12 shows the reflectance R of the SCI method in the near infrared region of the embodiment. SCI 12, which shows the maximum reflectance at wavelengths of 1000 nm to 2000 nm. SCI For example, in Example 2, the maximum reflectance R SCI is 0.14%, so the reflectance RSCI From this, it is understood that the light absorbers of these Examples exhibit excellent extremely low reflectance in the wavelength range from visible to near infrared.

[0097] Reflectance R of the SCI method in the near infrared SCI The measurement method is to use a PerkinElmer UV-Vis-NIR spectrophotometer (product name LAMBDA 900) with a hemispherical reflectance measurement unit (Spectralon integrating sphere), and measure the reflectance R at 10 nm intervals in the measurement wavelength range of 1000 nm to 2000 nm under the condition of 8° / di (8° direction incidence / diffuse reception, including specular reflection component). SCI The measured value was obtained by subtracting the baseline signal generated when no sample was placed in the sample port. A calibrated Spectralon 99% standard reflector (product number SRS-99-020, manufactured by Labsphere, USA) was used as the reference standard. The maximum reflectance R SCI is shown in Figure 12.

[0098] Although the embodiments and examples of the present invention have been described in detail above, the present invention is not limited to such specific embodiments and examples, and various modifications and variations are possible within the scope of the present invention described in the claims.

[0099] Furthermore, the light absorber according to the embodiment of the present invention is useful in professional applications (spectroscopic analysis, space telescopes, etc.) that require an extremely high level of anti-reflection performance, and in real life. For example, it can be applied to preventing inner reflection of the barrel of a camera lens, preventing glare on a car dashboard, increasing the contrast of a display, decoration with a luxurious black finish, etc.

Claims

1. A light absorber comprising: A light absorbing layer made of a resin containing a light absorbing material is provided. a light trapping structure is formed on the surface of the light absorber, the light absorbing material is configured so that a luminous reflectance R SCE of 0.20% or less is measured using a Specular Components Excluded (SCE) method for detecting diffuse reflected light when the surface of the light absorbing layer is mirror-finished; The light absorber has a luminous reflectance R SCI The light absorber is configured so that the optical transmittance is 0.20% or less.

2. 2. The light absorber according to claim 1, wherein the light confinement structure has a plurality of protrusions formed so as to protrude outward from the surface, the protrusions have tips that are connected in a ridge-like shape or are conical, and have a cross-sectional shape that gradually widens from the tip to the base, and the distance between adjacent ridges or adjacent conical tips is 0.1 μm to 100 μm.

3. The light absorber according to claim 1 , wherein the mirror-finished surface is formed by filling a transparent resin onto the surface on which the light trapping structure is formed.

4. The light absorber according to claim 1 , wherein the mirror-finished surface is formed by flattening the surface on which the light trapping structure is to be formed.

5. The light absorber according to any one of claims 1 to 4, wherein the light absorbing material comprises a material selected from the group consisting of black lacquer, inorganic black pigment, oriented carbon nanotubes and black dye.

6. The light absorber according to claim 5 , further comprising a porous inorganic black film or a resin layer containing carbon black under the light absorbing layer when the light absorbing material is black lacquer or black dye.

7. 6. The light absorber according to claim 5, further comprising carbon black as the light absorbing material when the light absorbing material is a black dye.

8. The light absorber according to any one of claims 1 to 7, wherein the resin of the light absorbing layer is at least one resin selected from the group consisting of epoxy resin, polyester resin, acrylic resin, polycarbonate resin and vinyl chloride resin.

9. The light absorber according to any one of claims 1 to 7, wherein the resin of the light absorbing layer is made of an ultraviolet curable resin.

10. The light absorber according to claim 1 , wherein the light absorbing layer has the light trapping structure formed on a surface thereof.

11. A light absorber comprising: a light absorbing layer including a light absorbing material; a surface layer made of a resin and having a light trapping structure on a surface of which a plurality of minute protrusions are formed, the surface layer being provided on the light absorbing layer; the light absorbing material is configured so that a luminous reflectance R SCE of 0.20% or less is measured using a Specular Components Excluded (SCE) method for detecting diffuse reflected light when the surface of the surface layer is mirror-finished; The light absorber has a luminous reflectance R SCI The light absorber is configured so that the optical transmittance is 0.20% or less.

12. 12. The light absorber according to claim 11, wherein the light confinement structure has a plurality of protrusions formed so as to protrude outward from the surface, the protrusions have tips which are connected in a ridge-like manner or are conical, the protrusions have a cross-sectional shape which gradually widens from the tips to the base, and the distance between adjacent ridges or adjacent conical tips is 0.1 μm to 100 μm.

13. The light absorber according to claim 11 , wherein the mirror finish is formed by filling a transparent resin onto the surface of the surface layer on which the light trapping structure is formed.

14. The light absorber according to claim 11 , wherein the mirror finish is formed by flattening the surface of the surface layer.

15. The light absorber according to any one of claims 11 to 14, wherein the light absorbing layer comprises a light absorbing material selected from the group consisting of black lacquer, inorganic black pigment, oriented carbon nanotube and black dye, and a resin, or comprises a light absorbing material selected from the group consisting of porous inorganic black film, electrostatic flocked black cloth and foamed polyurethane black sheet.

16. 16. The light absorber of claim 15, further comprising carbon black as the light absorbing material when the light absorbing material is a black dye.

17. 16. The light absorber according to claim 15, further comprising a porous inorganic black film or a resin layer containing carbon black under the light absorbing layer, when the light absorbing material is black lacquer, oriented carbon nanotubes or black dye.

18. The light absorber according to any one of claims 11 to 17, wherein the surface layer comprises a black dye.

19. The light absorber according to any one of claims 11 to 18, wherein the surface layer is made of at least one resin selected from the group consisting of epoxy resin, polyester resin, acrylic resin, polycarbonate resin and vinyl chloride resin.

20. The light absorber according to any one of claims 11 to 18, wherein the surface layer is made of an ultraviolet curable resin.

21. The light absorber has a luminous reflectance R SCI The light absorber according to any one of claims 1 to 20, configured so that the optical transmittance is 0.10% or less.

22. A method for producing a light absorber, comprising the steps of: forming a precursor of a light absorbing layer by using a light absorbing material and a resin liquid; and before the resin liquid is cured, pressing a mold having a plurality of minute protrusions formed on the surface of the precursor onto the surface of the precursor to cure the resin liquid, thereby forming a light absorbing layer having a light trapping structure on the surface of the precursor. the light absorbing material comprises a material selected from the group consisting of black lacquer, inorganic black pigment, oriented carbon nanotubes and black dye; the light absorbing material is configured so that a luminous reflectance R SCE of 0.20% or less is measured using a Specular Components Excluded (SCE) method for detecting diffuse reflected light when the surface of the light absorbing layer is mirror-finished; The light absorber has a luminous reflectance R SCI The manufacturing method according to claim 1, wherein the content of the Cr is 0.20% or less.

23. A method for producing a light absorber, comprising the steps of: forming a light absorbing layer comprising a light absorbing material selected from the group consisting of black lacquer, inorganic black pigment, oriented carbon nanotube and black dye, and a resin, or a light absorbing material selected from the group consisting of porous inorganic black film, electrostatic flocked black cloth and foamed polyurethane black sheet; applying a resin liquid to a surface of the light absorbing layer; and before the resin liquid is cured, pressing a mold having a plurality of minute protrusions formed on its surface to cure the resin liquid, thereby forming a surface layer having a light confinement structure on the surface, the light absorbing material is configured so that a luminous reflectance R SCE of 0.20% or less is measured using a Specular Components Excluded (SCE) method for detecting diffuse reflected light when the surface of the surface layer is mirror-finished; The light absorber has a luminous reflectance R SCI The manufacturing method according to claim 1, wherein the content of the Cr is 0.20% or less.

24. forming the mold; 24. The manufacturing method according to claim 22 or 23, wherein the step of forming the mold includes the steps of irradiating a resin substrate with an ion beam, etching the irradiated resin substrate with an alkaline solution to form a textured surface on its surface, and applying a resin liquid to the textured surface of the etched resin substrate to form the mold.

25. forming the mold; 24. The manufacturing method according to claim 22 or 23, wherein the step of forming the mold includes the steps of irradiating a resin substrate with an ion beam, etching the irradiated resin substrate with an alkaline solution to form an uneven surface on its surface, applying a resin liquid to the uneven surface of the etched resin substrate to form a transfer body, and applying a resin liquid to the uneven surface of the transfer body to form the mold.

26. The method according to claim 24 or 25, wherein the resin substrate is made of allyl diglycol carbonate resin (CR-39).

27. The method according to any one of claims 22 to 26, wherein the mold is made of a gas-permeable elastomeric material.

28. The manufacturing method according to any one of claims 22 to 27, wherein the mold has a plurality of protrusions formed to protrude outward from a surface thereof, the protrusions have tips that are connected in a ridge-like manner or are conical, the protrusions have a cross-sectional shape that gradually widens from the tip to the base, and the distance between adjacent ridges or adjacent conical tips is 0.1 μm to 100 μm.

Images