Optical body and method for manufacturing optical body

Abstract

To achieve both heat countermeasures and securing a communication environment in an optical body used in heat ray reflective glass and the like.SOLUTION: An optical body 1 according to the present disclosure includes a first optical layer 2 having a plurality of fine uneven structures 20 extending in a first direction formed on one surface thereof, a heat ray reflective film 3 formed disproportionately on a partial region of each of the plurality of fine uneven structures 20, and a second optical layer 4 formed on one surface of the first optical layer 2 and on the heat ray reflective film 3.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an optical body and a method for manufacturing the optical body.

Background Art

[0002] As a countermeasure against heat entering indoors due to solar radiation, particularly heat ray reflecting glass that reflects near-infrared rays and Low-E (Low Emissivity) glass are used. However, since these glasses reflect solar radiation specularly, reflected light pours onto the outdoor ground, and the resulting increase in ground temperature, particularly the adverse effects of local temperature increase, have become a problem.

[0003] As a countermeasure against this, Patent Documents 1 and 2 describe a technique in which a fine concavo-convex structure is provided on one surface of a base material constituting an optical body, and a reflective film that reflects heat rays (near-infrared rays) is formed on the fine concavo-convex structure.

[0004] In recent years, ensuring a communication environment indoors has become necessary along with heat countermeasures. In conventional heat ray reflecting glass and Low-E glass, the reflective film that reflects near-infrared rays also has a shielding property for radio waves used in communication, so the radio wave permeability is impaired. As a result, ensuring a communication environment necessary for high-speed large-capacity communication in recent years has become an issue.

[0005] To solve the above problems, Patent Document 3 describes a technique of providing a radio wave transmission member in a part within the plane of a window glass. Further, Patent Document 4 describes a technique of installing a transmitting and receiving antenna on a Low-E glass provided with a radio wave transmission part in a part of the window glass as in Patent Document 3.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

[0007] According to the techniques described in Patent Documents 1 and 2, visible light can be transmitted and near-infrared light can be reflected upward. However, in the techniques described in Patent Documents 1 and 2, since a reflective film is formed on the entire surface of the substrate having the fine uneven structure, radio waves cannot be transmitted, and it is difficult to secure a communication environment.

[0008] Also, according to the techniques described in Patent Documents 3 and 4, it is possible to secure a communication environment by providing a radio wave transmission member or an antenna for transmission and reception. However, in the technique described in Patent Document 3, there is a risk of impairing the countermeasure against heat and humidity. Further, in the technique described in Patent Document 4, there are problems such as an increase in the temperature of the ground surface due to the specular reflection of infrared rays and thermal cracking of the glass due to local solar radiation absorption in the antenna portion.

[0009] As described above, it has been difficult to achieve both heat and humidity countermeasures and secure a communication environment with the techniques described in Patent Documents 1 to 4.

[0010] An object of the present disclosure made in view of the above problems is to provide an optical body and a method for manufacturing the optical body capable of achieving both heat and humidity countermeasures and securing a communication environment. [Means for Solving the Problems]

[0011] (1) The optical body according to the present disclosure includes a first optical layer having a plurality of fine uneven structures extending in a first direction formed on one surface, a heat ray reflective film formed in a partial region of each of the plurality of fine uneven structures, and a second optical layer formed on the one surface of the first optical layer and on the heat ray reflective film.

[0012] (2) In the optical body according to (1), the heat ray reflecting film is formed so as to be biased to a position where the heat rays incident from above can be reflected upward or scattered in the fine uneven structure.

[0013] (3) In the optical body according to (1) or (2), the fine uneven structure is a structure having a cross section in a mountain shape as viewed from the first direction, formed by a first surface extending in the first direction and a second surface extending in the first direction and in contact with the first surface, and the heat ray reflecting film is formed so as to be biased to the first surface.

[0014] (4) In the optical body according to (3), the heat ray reflecting film is formed on the first surface, and the heat ray reflecting film is not formed on the second surface, or the heat ray reflecting film is formed thinner than the first surface.

[0015] (5) In the optical body according to (3) or (4), the first surface has a larger area in plan view than the second surface.

[0016] (6) In the optical body according to any one of (1) to (5), the height of the fine uneven structure changes in the first direction, and / or the top or ridge line of the fine uneven structure meanders as viewed from the first direction.

[0017] (7) In the optical body according to any one of (1) to (6), a plurality of fine uneven structures extending in a second direction are further formed on the one surface of the first optical layer, and the heat ray reflecting film is formed so as to be biased to a partial region of each of the plurality of fine uneven structures extending in the second direction.

[0018] (8) In the optical body according to any one of (1) to (7), at least a part of the heat ray reflecting film is transmissive to visible light.

[0019] (9) In the optical body according to (3), the mountain-shaped shape has a steep surface, and the angle formed by the surface and the main surface of the optical body is 90 degrees or more.

[0020] (10) In the optical body according to (4), the heat ray reflecting film formed on the first surface can selectively specularly reflect light in a specific wavelength range of solar radiation components in a direction other than the regular reflection (-θ, φ + 180°).

[0021] (11) In the optical body according to (4), the heat ray reflecting film formed on the second surface is permeable to radio waves.

[0022] (12) In the optical body according to (4), the thickness of the heat ray reflecting film formed on the first surface is 5 nm or more and 200 nm or less.

[0023] (13) In the optical body according to (4), the thickness of the heat ray reflecting film formed on the second surface is less than 5 nm.

[0024] (14) In the optical body according to (1), the radio wave transmittance of radio waves whose polarization direction is orthogonal to the extending direction of the heat ray reflecting film is higher than the radio wave transmittance of radio waves whose polarization direction is parallel to the extending direction of the heat ray reflecting film.

[0025] (15) The method for manufacturing an optical body according to the present disclosure is a method for manufacturing an optical body, including a step of forming a plurality of fine concavo-convex structures extending in a first direction on one surface of a first optical layer, a step of forming a heat ray reflecting film by preferentially depositing the heat ray reflecting film on a partial region of each of the plurality of fine concavo-convex structures, and a step of forming a second optical layer on the one surface of the first optical layer and on the heat ray reflecting film.

[0026] (16) In the method for manufacturing an optical body according to (15), the heat ray reflecting film is formed by a sputtering method or a vapor deposition method so that a film thickness difference of the heat ray reflecting film occurs.

[0027] In the method for manufacturing the optical body described in (17) (15), the heat ray reflecting film is formed by an oblique film formation method.

Effect of the Invention

[0028] According to the present disclosure, in an optical body used for heat ray reflecting glass or the like, it is possible to achieve both heat countermeasures and ensuring a communication environment.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9A

Figure 9B

Figure 9C

Figure 10

Figure 11

Figure 12A

Figure 12B

Figure 12C

Embodiments for Carrying Out the Invention

[0030] Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. In each figure, the same reference numerals indicate the same or equivalent components.

[0031] FIG. 1 is a cross-sectional view showing a configuration example of an optical body 1 according to an embodiment of the present disclosure. The optical body 1 according to the present embodiment reflects heat rays (near-infrared rays) and transmits radio waves. The optical body 1 according to the present embodiment is, for example, a film-shaped, sheet-shaped, plate-shaped or block-shaped member. When the optical body 1 is a flexible film-shaped or sheet-shaped member, the optical body 1 may be attached to, for example, a window material. Further, when the optical body 1 is a rigid plate-shaped or block-shaped member, the optical body 1 may be attached to, for example, a window frame or the like as a window material.

[0032] As shown in FIG. 1, the optical body 1 according to the present embodiment includes a first optical layer 2, a heat ray reflecting film 3, and a second optical layer 4. The first optical layer 2 and the second optical layer 4 face each other, and the heat ray reflecting film 3 is provided between the first optical layer 2 and the second optical layer 4.

[0033] The optical body 1 may have transparency, or may scatter visible light like ground glass. When the optical body 1 has transparency, it is preferable that the first optical layer 2 and the second optical layer 4 have the same optical properties such as refractive index. By configuring the first optical layer 2 and the second optical layer 4 with the same material, the refractive indices of both become equal, so that the transparency of visible light can be improved.

[0034] When the optical body 1 is a film-like or sheet-like member and is to be attached to a window glass or the like, all or the surface of the optical layer on the side to be attached to the window glass or the like among the first optical layer 2 and the second optical layer 4 may be mainly composed of an adhesive.

[0035] Examples of the window material include building window materials such as those for high-rise buildings or houses, and window materials for vehicles. When applying the optical body 1 to a building window material, it is particularly preferable to apply the optical body 1 to a window material arranged from southeast to southwest. By applying it to a window material in such a position, heat rays can be reflected more effectively.

[0036] The first optical layer 2 supports and protects the heat ray reflecting film 3. The first optical layer 2 is, for example, a film-like, sheet-like, plate-like or block-like member. From the viewpoint of enabling the optical body 1 to be easily bonded to the window material, the first optical layer 2 is preferably a film-like or sheet-like member. As the material of the first optical layer 2, for example, thermoplastic resins such as polycarbonate, and ionizing radiation curable resins such as acrylic can be used.

[0037] FIG. 2 is a perspective view of the first optical layer 2. As shown in FIG. 2, on one surface of the first optical layer 2 (the surface facing the second optical layer 4), a one-dimensionally arranged fine concavo-convex structure 20 is formed to extend in a predetermined direction (the first direction).

[0038] FIG. 3 is a cross-sectional view of the first optical layer 2 along the line A-A' shown in FIG. 2. Further, FIG. 4 is a view of the first optical layer 2 as seen from above.

[0039] As shown in FIG. 3, the fine concavo-convex structure 20 is formed by the first surface 21 extending in a predetermined direction (the first direction) and the second surface being in contact with one side of each surface. That is, the fine concavo-convex structure 20 is a structure having a mountain-shaped cross-section when viewed from the first direction.

[0040] As shown in FIG. 3, the inclination of the first surface 21 is smaller than the inclination of the second surface 22. Therefore, as shown in FIG. 4, the first surface 21 has a larger area in plan view than the second surface 22.

[0041] Referring to FIG. 1 again, the heat ray reflecting film 3 is formed so as to be concentrated on a partial region of each of the plurality of fine concavo-convex structures 20. More specifically, the heat ray reflecting film 3 is formed so as to be concentrated on the first surface 21. Therefore, the first surface 21 mainly serves as a surface for reflecting heat rays. Hereinafter, in the fine concavo-convex structure 20, the surface that mainly reflects heat rays is referred to as the main reflecting surface, and the surfaces other than the main reflecting surface are referred to as other surfaces.

[0042] In FIG. 1, an example is shown in which the heat ray reflecting film 3 is formed only on the first surface 21 of the fine concavo-convex structure 20, but the present disclosure is not limited to this, and the heat ray reflecting film 3 may also be formed on the second surface 22. However, in the present embodiment, the film thickness of the heat ray reflecting film 3 formed on the second surface 22 is made thinner than the film thickness of the heat ray reflecting film 3 formed on the first surface 21. That is, forming the heat ray reflecting film 3 so as to be concentrated on the first surface 21 means that the heat ray reflecting film 3 is formed on the first surface 21 and not formed on the second surface 22, or the heat ray reflecting film 3 is formed on the second surface 22 thinner than the first surface 21.

[0043] The heat ray reflecting film 3 reflects near-infrared rays (heat rays). The heat ray reflecting film 3 may transmit visible light. The heat ray reflecting film 3 is, for example, a laminated film formed by alternately laminating low refractive index layers and high refractive index layers having different refractive indexes. Further, the heat ray reflecting film 3 is, for example, a laminated film formed by alternately laminating a metal layer having a high reflectance in the infrared region and an optical transparent layer or a transparent conductive film having a high refractive index in the visible region.

[0044] Near-infrared rays are defined in JISA1494 as having a wavelength range of 780 to 2500 nm. Also, as window glass, in order to meet the requirements of outlook, transparency, and daylighting, it is desirable to be able to transmit in the visible range of 380 to 780 nm described in JISA1494. From the above, it is desirable for the heat ray reflective film 3 to selectively reflect heat rays.

[0045] A metal layer with high reflectivity in the infrared region is mainly composed of, for example, a single substance such as Au, Ag, Cu, Al, Ni, Cr, Ti, Pd, Co, Si, Ta, W, Mo, Ge, or an alloy containing two or more of these single substances. Considering practicality, materials of Ag-based, Cu-based, Al-based, Si-based, or Ge-based are preferred. Also, when using an alloy as the material of the metal layer, the metal layer is preferably mainly composed of AlCu, AlTi, AlCr, AlCo, AlNdCu, AlMgSi, AgPdCu, AgPdTi, AgCuTi, AgPdCa, AgPdMg, AgPdFe, Ag, or SiB, etc. Further, in order to suppress the corrosion of the metal layer (especially Ag), it is preferable to add materials such as Ti and Nd to the metal layer.

[0046] The optical transparent layer has a high refractive index in the visible region and is mainly composed of a high dielectric such as niobium oxide, tantalum oxide, titanium oxide, etc. The transparent conductive film is preferably mainly composed of, for example, zinc oxide, indium-doped tin oxide, etc.

[0047] Note that the laminated film is not limited to a thin film made of an inorganic material, and may also be composed of a thin film made of a polymer material or a layer in which fine particles, etc. are dispersed in the polymer. Also, in order to prevent the oxidative degradation of the underlying metal during the film formation of these optical transparent layers, a thin buffer layer of about several nm of Ti or the like may be provided at the interface of the optical transparent layer to be formed. The buffer layer is a layer for suppressing the oxidation of the underlying metal layer, etc. by oxidizing itself during the formation of the upper layer film.

[0048] The average thickness of the heat ray reflecting film 3 formed on the first surface 21 is not particularly limited, but is preferably 5 nm or more and less than 200 nm. If the average thickness of the metal layer is less than 5 nm, even if the surface is smooth, light may transmit through and not be reflected. If the average thickness of the metal layer is 200 nm or more, the transmittance of visible light will decrease more than necessary. Note that the average thickness of the heat ray reflecting film 3 is more preferably 85 nm or less, even more preferably 40 nm or less, and particularly preferably 25 nm or less.

[0049] Examples of the method for measuring the average thickness of the heat ray reflecting film 3 include cross-section measurement by a transmission electron microscope, measurement by a fluorescent X-ray film thickness meter, X-ray reflectivity method, and the like.

[0050] The second optical layer 4 is formed on one surface of the first optical layer 2 and on the heat ray reflecting film 3. The second optical layer 4 supports and protects the heat ray reflecting film 3. As the material of the second optical layer 4, for example, a thermoplastic resin such as polycarbonate, an ionizing radiation curable resin such as acrylic, or the like can be used. Further, the whole or the surface of the second optical layer 4 may be used as an adhesive layer, and the optical body 1 may be bonded to the window material through this adhesive layer. As the material of the adhesive layer, for example, a pressure sensitive adhesive (PSA), an ultraviolet curable resin, or the like can be used.

[0051] FIG. 5 is a diagram for explaining the reflection of solar radiation by a conventional reflective glass 40 in which a reflective film 42 is formed on one surface of a flat glass 41 such as Low-E glass. Usually, solar radiation from the sun arrives obliquely from above as shown in FIG. 5. In the conventional reflective glass 40, since the reflective film 42 is formed on one surface of the flat glass 41, the solar radiation arriving obliquely from above is specularly reflected obliquely downward, that is, in the direction of the ground as shown in FIG. 5. Note that specular reflection means that, as shown in FIG. 6, light L incident on the incident surface S1 at the incident angle (θ, φ) is reflected as the reflected angle L1 of the reflection angle (-θ, φ + 180°). θ is the vertical azimuth angle, which is the angle formed by the perpendicular line l1 to the incident surface S1 and the incident light L or the reflected light L1. Further, φ is the azimuth shell, which is the angle formed by a specific straight line l2 in the incident surface S1 and the component obtained by projecting the incident light L or the reflected light L1 onto the incident surface.

[0052] In the present embodiment, as shown in FIG. 7, the optical body 1 is installed such that the main reflection surface on which the heat ray reflection film 3 is unevenly formed faces obliquely upward. By installing the optical body 1 in this way, as shown in FIG. 7, the solar radiation (near-infrared rays) arriving obliquely from above is reflected upward by the heat ray reflection film 3. That is, in the optical body 1 according to the present disclosure, the heat ray reflection film 3 formed on the first surface 21 can selectively specularly reflect light in a specific wavelength range of the solar radiation component in a direction other than the specular reflection (-θ, φ + 180°).

[0053] Furthermore, in the present embodiment, as described above, the heat ray reflection film 3 is unevenly formed in a partial region of the fine uneven structure 20. For example, as described with reference to FIGS. 1 to 4, the heat ray reflection film 3 is formed on the first surface 21 of the fine uneven structure 20, and the heat ray reflection film 3 is not formed on the second surface 22 (the other surface) of the fine uneven structure 20, or the heat ray reflection film 3 is formed thinner than the first surface 21.

[0054] Since there is a region where the heat ray reflecting film 3 is not formed or a region where the heat ray reflecting film 3 is formed thinly, according to the optical body 1 according to the present embodiment as shown in FIG. 8, radio waves with a polarization direction parallel to the extending direction (horizontal direction of the paper surface) of the heat ray reflecting film 3 are reflected, but the polarization direction is rotated by 90 deg with respect to the extending direction (horizontal direction of the paper surface) of the heat ray reflecting film 3, and radio waves incident from the vertical direction can be transmitted. From the viewpoint of such radio wave transmission, the pitch of the fine uneven structure 20 is preferably 1 / 2 or less of the wavelength of the radio wave to be transmitted, and more preferably 1 / 3 to 1 / 4 or less of the wavelength of the radio wave to be transmitted.

[0055] Here, according to the definition of the Ministry of Internal Affairs and Communications, the "radio wave" is an electromagnetic wave of 3 million MHz or less (3000 GHz or less). In recent years, frequencies in the millimeter wave band such as local 5G are 28.3 to 29.1 GHz, and in the Sub6 band, frequencies in the 4.6 to 4.9 GHz band are used (according to the NTT East Japan homepage, etc.). When these are converted into wavelength bands, they are 10.593 to 10.302 mm and 65.172 to 61.182 mm, and any structure with a pitch sufficiently smaller than these wavelengths may be used. Also, according to JISA5759, the solar radiation component from sunlight is in the range of 300 to 2500 nm. Therefore, any structure with a pitch larger than the wavelengths of these lights may be used, and the pitch size of the structure may be appropriately selected in view of radio wave transmissibility and heat ray reflection characteristics. Note that the pitch refers to the interval between the respective structures constituting the fine uneven structure 20.

[0056] As described with reference to FIGS. 7 and 8, according to the optical body 1 according to the present embodiment, near-infrared rays can be reflected (upward reflection) and radio waves can be transmitted. Therefore, according to the optical body 1 according to the present embodiment, in an optical body used for heat ray reflecting glass or the like, it is possible to achieve both heat countermeasures and ensuring a communication environment.

[0057] Here, the radio wave transmissivity when the heat ray reflecting film 3 is also formed on the second surface 22 of the fine uneven structure 20 will be described with reference to FIGS. 9A to 9C and Tables 1 to 3. In Table 1, the surface electrical resistivity and the radio wave transmissivity are shown when the heat ray reflecting film 3 containing Ag is formed on a flat PET film with film thicknesses of 15, 11, 7, 5, 3, and 2 nm. FIG. 9A is a diagram plotting the values of the surface electrical resistivity and the radio wave transmissivity for each film thickness of the heat ray reflecting film 3 shown in Table 1, and is a diagram showing the thickness-surface electrical resistivity - radio wave transmissivity characteristics of the heat ray reflecting film 3. As the material of the heat ray reflecting film 3, the Ag-based reflective film of Example 1 described later was used. The measurement methods for each parameter were as follows. Surface electrical resistivity: Mitsubishi Chemical Loresta MCP-T610, applied voltage 10V, probe ASP 4-terminal method Radio wave transmissivity: Using an impedance analyzer, the transmission amount of the input radio wave was measured by the S-parameter transmission method. The frequency band of the radio wave was 3.95 to 5.85 GHz. The transmission amount was the average value of the transmission amounts in the above-described band.

[0058]

Table 1

[0059] As shown in FIG. 9A, when the thickness (average thickness) of the Ag-based reflective film is about 5 nm or less, as the thickness of the Ag-based reflective film decreases, the surface electrical resistivity increases, and accordingly, the radio wave transmissivity also increases. From this, it can be seen that even if a heat ray reflecting film 3 of about several nm is formed on the second surface 22 (a surface other than the main reflecting surface) of the fine uneven structure 20, radio waves can be transmitted.

[0060] In Tables 2 and 3, the surface electrical resistivity and the radio wave transmissivity are shown when the heat ray reflecting film 3 (Ag-based reflective film) containing Ag is formed on the first optical layer 2 shown in FIG. 2 with different film thicknesses. The film thicknesses in the table were calculated by converting in terms of the increased projected area of the slope portion of the thickness (average thickness) of the Ag-based reflective film. FIG. 9B is a diagram plotting the values of the electrical resistivity and the radio wave transmittance at each film thickness of the heat ray reflecting film shown in Table 2, and shows the thickness - electrical resistivity · radio wave transmittance characteristics of the heat ray reflecting film 3 when the extending direction of the fine concavo - convex structure 20 and the polarization direction of the radio wave are parallel. FIG. 9C is a diagram plotting the values of the electrical resistivity and the radio wave transmittance at each film thickness of the heat ray reflecting film shown in Table 3, and shows the thickness - electrical resistivity · radio wave transmittance characteristics of the heat ray reflecting film 3 when the extending direction of the fine concavo - convex structure 20 and the polarization direction of the radio wave are orthogonal. In FIGS. 9B and 9C, an example is shown in which the cross - section of the fine concavo - convex shape is a scalene triangle where the bottom angle of the first surface 21 is 35 deg (35 - deg surface) and the bottom angle of the second surface 22 is 55 deg (55 - deg surface). Also, FIGS. 9B and 9C show the characteristics when an Ag - based reflective film is formed on the first optical layer 2.

[0061]

Table 2

[0062]

Table 3

[0063] Compared with FIG. 9A, FIGS. 9B and 9C have a higher surface electrical resistivity and a higher radio wave transmittance. This is considered to be because a slope due to the fine concavo - convex structure 20 is formed on the first optical layer 2, the film formation amount (thickness) per unit projected area changes, and the Ag - based reflective film is formed thinner on the steeper slope (the second surface 22).

[0064] When comparing FIG. 9B and FIG. 9C, since the film formation state of the Ag - based reflective film on the fine concavo - convex structure 20 is uneven, it can be seen that the surface electrical resistivity also changes in the in - plane direction. As a result, it was confirmed that the radio wave transmittance of the radio wave whose polarization direction is orthogonal to the extending direction of the heat ray reflecting film 3 (FIG. 9C) is improved (higher) than the radio wave transmittance of the radio wave whose polarization direction is parallel to the extending direction of the heat ray reflecting film 3 (FIG. 9B).

[0065] Thus, in the present embodiment, a plurality of fine concavo-convex structures 20 are provided on the first optical layer 2, and the heat ray reflecting film 3 is formed by concentrating on a partial region of each of the plurality of fine concavo-convex structures 20. By doing so, in an optical body used for a heat ray reflecting glass or the like, it is possible to achieve heat countermeasures and ensure a communication environment.

[0066] From the results of FIG. 9 and Table 1, the thickness of the heat ray reflecting film 3 on the second surface 22 of the fine concavo-convex structure 20 is preferably less than 5 nm, more preferably 3 nm or less, and even more preferably 2 nm or less.

[0067] In the present embodiment, an example in which the cross-sectional shape of the fine concavo-convex structure 20 is a mountain shape has been described, but the present invention is not limited thereto. The cross-sectional shape of the fine concavo-convex structure 20 may be a hemispherical shape, a semi-elliptical spherical shape, a prism shape, a free-form surface shape, a polygonal shape, a conical shape, a polygonal pyramid shape, a truncated cone shape, a paraboloidal shape, a shape with rounded corners at the top of a polygon, or the like.

[0068] In terms of heat countermeasures, when downward reflection of near-infrared rays occurs, problems such as an increase in ground temperature may occur. Therefore, the heat ray reflecting film 3 is preferably formed by concentrating on a position where heat rays incident from above the sky can be reflected upward or scattered, in accordance with the shape of the fine concavo-convex structure 20.

[0069] In the present embodiment, an example in which the fine concavo-convex structure 20 linearly extends in a predetermined direction (first direction) with a uniform height has been described, but the present invention is not limited thereto. As shown in FIG. 10, the height of the fine concavo-convex structure 20 may change in the extending direction (first direction) of the fine concavo-convex structure 20. Further, the top or the ridge line (in the mountain shape) of the fine concavo-convex structure 20 may meander when viewed from the extending direction (first direction) of the fine concavo-convex structure 20. By adopting such a configuration, compared with a configuration in which the fine concavo-convex structures 20 are regularly provided, the reflected light can be scattered in more directions.

[0070] Also, in this embodiment, an example has been described in which only the fine concavo-convex structure 20 extending in a predetermined direction (first direction) is formed on one surface of the first optical layer 2, but the present invention is not limited to this. A plurality of fine concavo-convex structures 20 extending in a second direction (for example, a direction orthogonal to the first direction) may be further formed on one surface of the first optical layer 2. In this case, the fine concavo-convex structure 20 is constituted by a matrix-shaped (lattice-shaped) structure. Further, the heat ray reflecting film 3 is formed so as to be concentrated on a predetermined partial region of each of the plurality of fine concavo-convex structures 20 extending in the first direction and / or the second direction.

[0071] Next, a method for manufacturing the optical body 1 according to this embodiment will be described. FIG. 11 is a flowchart showing a method for manufacturing the optical body 1 according to this embodiment.

[0072] First, a plurality of fine concavo-convex structures 20 extending in a predetermined direction (first direction) are formed on one surface of the first optical layer 2 (step S11). The fine concavo-convex structure 20 is produced by transferring the inverted shape of a master disk having a convex shape formed thereon. The master disk is, for example, a roll-shaped master disk. Such a master disk is produced, for example, as follows. First, while rotating a roll-shaped member, a cutting tool having a tip portion of a predetermined shape is applied to the roll-shaped member so as to cut at a predetermined depth to cut the roll-shaped member. When the cutting for one circumference of the roll-shaped member is completed, the cutting tool is moved by a predetermined distance in a direction orthogonal to the rotation direction, and the cutting of the roll-shaped member is restarted. By repeating this, a master disk having a predetermined convex shape can be obtained.

[0073] The produced master disk is pressed against an uncured resin sheet, or the uncured resin sheet is pressed against the produced master disk, and the inverted shape of the master disk is transferred to the resin sheet, and the resin sheet is cured, whereby the first optical layer 2 having a plurality of fine concavo-convex structures 20 extending in a predetermined direction can be produced.

[0074] Next, the heat ray reflective film 3 is preferentially formed on a partial region of each of the plurality of fine concavo-convex structures 20 (step S12). As a method for forming the heat ray reflective film 3 preferentially on a partial region, for example, as shown in FIG. 12A, there is a method of forming the heat ray reflective film 3 by sputtering from an oblique direction with respect to the first optical layer 2 (oblique film formation). In this method, the heat ray reflective film 3 is formed by sputtering from a direction facing the main reflection surface (in the example shown in FIG. 12A, the first surface 21 of the fine concavo-convex structure 20). As other film formation methods, a vacuum evaporation method, an atomic layer deposition method (ALD), or the like can be used.

[0075] Further, as another method for forming the heat ray reflective film 3 preferentially on a partial region, there is a method of configuring the structure of the first optical layer 2 such that the heat ray reflective film 3 is less likely to be formed on surfaces other than the main reflection surface. In this method, for example, as shown in FIG. 12B, in the first optical layer 2, surfaces other than the main reflection surface (in the example shown in FIG. 12B, the second surface 22 of the fine concavo-convex structure 20) are made into steep surfaces, and the heat ray reflective film 3 is formed by sputtering from above (in the vertical direction) of the first optical layer 2. By doing so, formation of the heat ray reflective film 3 on the steep other surfaces can be suppressed.

[0076] Furthermore, the original disk of the concavo-convex shape may be set so as to exceed 90 degrees (so as to be an acute angle) as the steep surface of the first optical layer 2. That is, the mountain-shaped shape formed on the first optical layer 2 has a steep surface, and the angle formed by the steep surface and the main surface of the optical body 1 may be 90 degrees or more. In this case, it becomes possible to make the resin layer forming the structure have appropriate elasticity and stretchability. In this way, the reflective film can be preferentially formed as appropriate by combining the method for forming the reflective film and the structure.

[0077] Moreover, as yet another method for forming the heat ray reflective film 3 preferentially on a partial region, as shown in FIG. 12C, the heat ray reflective film 3 is formed over the entire surface of the first optical layer 2, and a part or all of the heat ray reflective film 3 formed on a surface other than the main reflection surface (in the example shown in FIG. 12C, the second surface 22 of the fine concavo-convex structure 20) is removed by cutting, polishing, or ablation using a laser.

[0078] Referring again to FIG. 11, a second optical layer 4 is formed on one surface of the first optical layer 2 on which the heat ray reflective film 3 is formed (step S13). Specifically, an uncured resin is applied onto one surface of the first optical layer 2 on which the heat ray reflective film 3 is formed. As the resin, for example, a thermoplastic resin or an ionizing radiation curable resin can be used. As the ionizing radiation curable resin, an ultraviolet curable resin is preferable. Next, a release film is placed over the resin to form a resin surface. Next, the resin is cured by irradiating the resin with UV light or by cooling the resin. By peeling the release film from the cured resin, a second optical layer 4 having a smooth surface is formed on the first optical layer 2.

[0079] In the optical body 1 obtained by the manufacturing method according to the present embodiment, in some regions (main reflection surfaces) where the heat ray reflective film 3 is formed unevenly, the heat ray reflective film 3 can reflect heat rays. Further, on other surfaces other than the main reflection surface, the heat ray reflective film 3 is not formed unevenly (that is, the heat ray reflective film 3 is not formed, or the heat ray reflective film 3 is formed thinner than some regions), so radio waves can be transmitted. Therefore, according to the manufacturing method of the optical body 1 according to the present disclosure, an optical body 1 capable of achieving both heat countermeasures and ensuring a communication environment can be provided.

Example

[0080] Next, the present disclosure will be described more specifically with reference to examples, but the present disclosure is not construed as being limited to the following examples.

[0081] (Example 1) First, a master disk in which a triangular prism having a cross-sectional shape of a scalene triangle extends in a predetermined direction was produced by cutting. The inclination of the surface corresponding to the main reflection surface was set to 35 deg, and the inclination of the surface corresponding to the other surfaces other than the main reflection surface was set to 55 deg. Further, the cutting pitch of the triangular prism was set to 67 μm, and the height (cutting depth) of the triangular prism was set to 31 μm.

[0082] Next, an ultraviolet curable resin (refractive index after curing: 1.52) was applied onto the produced master disk, and the ultraviolet curable resin was sandwiched with an easily adhesive treated PET film (75 μm), and then the ultraviolet curable resin was cured. After the ultraviolet curable resin was cured, the PET film was peeled off from the master disk, and a film having a fine concavo-convex structure with a cross-section being a scalene triangle and extending in a predetermined direction was produced.

[0083] Next, a reflective film was formed (oblique film formation) on the produced film. The reflective film had a five-layer structure ((ZnO(TiO2)): 36 nm / AgPdCu: 15 nm / (ZnO(TiO2)): 83 nm / AgPdCu: 8 nm / (ZnO(TiO2)): 36 nm). For sputtering, a sputtering film forming machine: SPH530 manufactured by CANON-ANELVA was used. Here, for forming the AgPdCu film, an alloy target having a composition of Ag / Pd / Cu = 98.1 mass% / 0.9 mass% / 1.0 mass% was used, and since oblique sputtering film formation was performed, a layer mainly composed of thick film Ag (Ag main component layer) was formed on the main reflective surface. In addition, an Ag main component layer with a thickness of 2 to 3 nm was formed on the surfaces other than the main reflective surface. Also, for forming the (ZnO(TiO2)) film, a ceramic target [ZnO:TiO2 = 100:20 (mass ratio)] in which 20 mass% of TiO2 was added to ZnO was used.

[0084] Next, an ultraviolet curable resin (refractive index after curing: 1.52) was applied onto the film on which the reflective film was formed, and the ultraviolet curable resin was sandwiched with an easily adhesive treated PET film (75 μm), and then the ultraviolet curable resin was cured to produce a transparent film (optical element).

[0085] (Example 2) In this example, a layer made of Ag with a thickness of 30 nm was formed as the reflective film on the main reflective surface. Other conditions were the same as those in Example 1.

[0086] (Example 3) In this embodiment, the shape of the fine concavo-convex structure was changed from that of Example 1. Specifically, the inclination of the surface serving as the main reflection surface was set to 20 deg, and the inclination of the other surfaces other than the main reflection surface was set to 88 deg. Then, a reflective film was formed on the film having the fine concavo-convex structure by sputtering from the perpendicular direction. On the main reflection surface, an Ag main component layer with a thickness of 10 nm was formed, and on the other surfaces, an Ag main component layer with a thickness of 4 nm was formed. Other conditions were the same as those in Example 1.

[0087] (Comparative Example 1) In this comparative example, the film on which the reflective film was formed was a flat plate-like film without a fine concavo-convex structure, and the reflective film was formed on the film by sputtering from the perpendicular direction. The thickness of the formed Ag main component layer was 12 nm. Other conditions were the same as those in Example 1.

[0088] (Comparative Example 2) In this comparative example, the method of forming the reflective film was changed from that of Example 1. Specifically, a reflective film was formed on the film having the same fine concavo-convex structure as in Example 1 by sputtering from the perpendicular direction. On the main reflection surface, an Ag main component layer with a thickness of 10 nm was formed, and on the other surfaces, an Ag main component layer with a thickness of 8 nm was formed. Other conditions were the same as those in Example 1.

[0089] (Comparative Example 3) In this comparative example, the shape of the fine concavo-convex structure was changed from that of Example 1. Specifically, the inclination of the surface serving as the main reflection surface was set to 30 deg, and the inclination of the other surfaces other than the main reflection surface was set to 79 deg. Then, a reflective film was formed on the film having the fine concavo-convex structure by sputtering from the perpendicular direction. On the main reflection surface, an Ag main component layer with a thickness of 11 nm was formed, and on the other surfaces, an Ag main component layer with a thickness of 7 nm was formed. Other conditions were the same as those in Example 1.

[0090] Next, using the films prepared in Examples 1-3 and Comparative Examples 1-3 as samples, the transparency, solar radiation characteristics (upward and downward reflectance of near-infrared rays), and radio wave transmissivity were evaluated. The transparency was evaluated based on whether the opposite side could be visually recognized through the prepared film. If the opposite side could be visually recognized through the film, it was evaluated as having transparency; if the opposite side could not be visually recognized through the film, it was evaluated as having no transparency. Also, when the opposite side could be visually recognized through the film and the reflection on the front side of the film could also be confirmed, it was evaluated as semi-transparent.

[0091] The upward reflectance of near-infrared rays was measured for the sample at a vertical azimuth angle θ of 60 deg from the normal direction (see Fig. 6) in accordance with "JIS A1494 Method for Measuring the Reciprocal Solar Radiation Reflectance Performance of Films for Architectural Window Glass". The azimuth angle φ of the incident light with respect to the sample was set to the direction in which the upward reflection performance of the sample was most efficiently exhibited. Then, the measured spectral reflectance value was multiplied by the overload factor in accordance with JIS A5759, and the upward reflection component in the near-infrared (wavelength 780 - 2500 nm) region was calculated as the upward reflectance.

[0092] The downward reflectance of near-infrared rays was measured for the sample at a vertical azimuth angle θ of 60 deg from the normal direction (see Fig. 6) in accordance with "JIS A1494 Method for Measuring the Reciprocal Solar Radiation Reflectance Performance of Films for Architectural Window Glass". In the measurement, the spectral reflectance value of the entire sample was measured, the spectral reflectance value of the upward reflection measured above was subtracted, and the downward reflection component in the near-infrared (wavelength 780 - 2500 nm) region was calculated as the downward reflectance by multiplying by the overload factor in accordance with JIS A5759.

[0093] The radio wave transmissivity was measured using an impedance analyzer by the S-parameter transmission method to measure the transmission amount of the input radio wave. The frequency band of the radio wave was 3.95 - 5.85 GHz. The transmission amount was taken as the average value of the transmission amounts in the above-mentioned band.

[0094] Table 4 shows the evaluation results of the transparency, solar radiation characteristics, and radio wave transmissivity (radio wave transmittance) of Examples 1-3 and Comparative Examples 1-3 respectively.

[0095]

Table 4

[0096] When comparing Example 1 and Comparative Example 1, as in Example 1, by forming a fine concavo-convex structure on the film and preferentially forming an Ag main component layer (heat ray reflecting film) on a part of the fine concavo-convex structure, it was confirmed that while suppressing the downward reflectance, high radio wave transmissivity can be obtained. Also, when comparing Example 1 and Comparative Example 2, in Comparative Example 2, a downward reflectance comparable to that of Example 1 was obtained. However, in Comparative Example 2, the radio wave transmittance was less than 1%. On the other hand, in Example 1, by obliquely depositing the reflecting film toward the main reflecting surface, the reflecting film was preferentially formed on the main reflecting surface, and as a result, it was confirmed that high radio wave transmissivity of 99% or more can be obtained.

[0097] Also, as in Example 2, even when the configuration of the reflecting film consists only of a layer mainly composed of Ag, it was confirmed that, similar to Example 1, while suppressing downward reflection, high radio wave transmissivity of 99% or more can be obtained.

[0098] Also, as in Example 3, even when the reflecting film is deposited from the perpendicular direction on a film having a fine concavo-convex structure with a large inclination on the surface other than the main reflecting surface, the reflecting film was preferentially formed on the main reflecting surface, and as a result, it was confirmed that while suppressing downward reflection, relatively high radio wave transmissivity of 74% can be obtained. Film deposition from the perpendicular direction is easier than oblique film deposition, so it is more advantageous from the viewpoint of productivity.

[0099] Also, when comparing Example 3 and Comparative Example 3, the inclination of the surface other than the main reflecting surface is gentler in Comparative Example 3. For this reason, in Comparative Example 3, the difference between the thickness of the reflecting film on the main reflecting surface and the thickness of the reflecting film on the other surface is smaller than that in Example 3. As a result, in Comparative Example 3, the thickness of the reflecting film on the other surface became relatively thick, and sufficient radio wave transmissivity could not be obtained. Therefore, it was confirmed that not only simply increasing the inclination of the other surface but also preferentially forming the reflecting film is important for obtaining radio wave transmissivity.

[0100] The present disclosure is not limited to the configurations described in the above-described embodiments, and various modifications are possible without departing from the gist of the invention described in the claims. For example, functions included in each configuration and the like can be rearranged so as not to be logically contradictory, and a plurality of configurations and the like can be combined into one or divided.

Explanation of Reference Numerals

[0101] 1 Optical body 2 First optical layer 3 Heat ray reflecting film 4 Second optical layer 20 Fine uneven structure 21 First surface 22 Second surface 40 Reflective glass 41 Glass 42 Reflective film

Claims

1. An optical body comprising: a first optical layer formed on one surface with a plurality of fine concavo-convex structures extending in a first direction; a heat ray reflecting film formed so as to be biased toward a partial region of each of the plurality of fine concavo-convex structures; and a second optical layer formed on the one surface of the first optical layer and on the heat ray reflecting film.

2. The optical body according to claim 1, wherein the heat ray reflecting film is formed so as to be biased to a position capable of reflecting or scattering heat rays incident from above in the fine concavo-convex structure.

3. The optical body according to claim 1, wherein the fine concavo-convex structure is a structure having a mountain-shaped cross section as viewed from the first direction, formed by a first surface extending in the first direction and a second surface extending in the first direction and in contact with the first surface; and the heat ray reflecting film is formed so as to be biased toward the first surface.

4. The optical body according to claim 3, wherein the heat ray reflecting film is formed on the first surface, and the heat ray reflecting film is not formed on the second surface or is formed thinner than on the first surface.

5. The optical body according to claim 3, wherein the first surface has a larger area in plan view than the second surface.

6. The optical body according to claim 1, wherein the height of the fine concavo-convex structure changes in the first direction and / or the top or ridge line of the fine concavo-convex structure meanders as viewed from the first direction.

7. The optical body according to claim 1, On one surface of the first optical layer, a plurality of fine concavo-convex structures extending in a second direction are further formed. The heat ray reflecting film is an optical body formed by being concentrated in a predetermined partial region of each of the plurality of fine concavo-convex structures extending in the second direction. **Claim 8** In the optical body according to claim 1, At least a part of the heat ray reflecting film is an optical body capable of transmitting visible light. **Claim 9** In the optical body according to claim 3, The mountain-shaped shape has a steep surface, and the angle formed by the surface and the main surface of the optical body is 90 degrees or more. **Claim 10** In the optical body according to claim 4, The heat ray reflecting film formed on the first surface is an optical body capable of selectively specularly reflecting light in a specific wavelength range of solar radiation components in a direction other than regular reflection (-θ, φ + 180°). **Claim 11** In the optical body according to claim 4, The heat ray reflecting film formed on the second surface is an optical body capable of transmitting radio waves. **Claim 12** In the optical body according to claim 4, The thickness of the heat ray reflecting film formed on the first surface is 5 nm or more and 200 nm or less. **Claim 13** In the optical body according to claim 4, The thickness of the heat ray reflecting film formed on the second surface is less than 5 nm. **Claim 14** In the optical body according to claim 1, The radio wave transmittance of radio waves whose polarization direction is orthogonal to the extending direction of the heat ray reflecting film is higher than the radio wave transmittance of radio waves whose polarization direction is parallel to the extending direction of the heat ray reflecting film. **Claim 15** A method for manufacturing an optical body, A step of forming a plurality of fine concavo-convex structures extending in a first direction on one surface of the first optical layer; A step of preferentially forming a heat ray reflecting film in a partial region of each of the plurality of fine concavo-convex structures; A method for manufacturing an optical body, comprising: a step of forming a second optical layer on the one surface of the first optical layer and on the heat ray reflecting film.

16. In the method for manufacturing an optical body according to claim 15, The method for manufacturing an optical body, wherein the heat ray reflecting film is formed by a sputtering method or a vapor deposition method so that a film thickness difference of the heat ray reflecting film occurs.

17. In the method for manufacturing an optical body according to claim 15, The method for manufacturing an optical body, wherein the heat ray reflecting film is formed by an oblique film formation method.

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