Light-transmitting member and shield

Abstract

To provide a technique that is advantageous in improving the functionality of a light-transmitting member. [Solution] A translucent member comprising a substrate containing a resin layer and a functional film disposed on the substrate, wherein the thickness of the substrate is 1 μm or more and less than 1 mm, the optical film thickness of the functional film for light having a wavelength of 464 nm or more and 653 nm or less is less than half the wavelength, the contact angle of water with the surface above the functional film on the translucent member is less than 90°, the functional film has a porous portion containing a large number of particles, and first particles and second particles among the large number of particles are bound to each other by a binder, and each of the first particles, second particles, and binder contains an inorganic material.

Description

[Technical field]

[0001] The present invention relates to a light-transmitting member. [Background technology]

[0002] There is a demand for improving the functionality of light-transmitting members using resin substrates. Patent Document 1 discloses an antireflection film in which a low refractive index layer is formed on a light-transmitting substrate film, and the low refractive index layer contains hollow silica fine particles or porous silica fine particles. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-283611 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is room for improving the functionality of the antireflection film described in Patent Document 1. Therefore, an object of the present invention is to provide a technique that is advantageous in improving the functionality of a light-transmitting member. [Means for solving the problem]

[0005] A first aspect of the means for solving the above problem is a light-transmitting member comprising a substrate including a resin layer and a functional film provided on the substrate, wherein the thickness of the substrate is 1 μm or more and less than 1 mm, the optical thickness of the functional film for light having a wavelength of 464 nm or more and 653 nm or less is less than half of the wavelength, the contact angle of water with the surface above the functional film in the light-transmitting member is less than 90°, the functional film has a porous portion containing a large number of particles, first particles and second particles among the large number of particles are bound to each other by a binder, and each of the first particles, the second particles, and the binder contains an inorganic material.

[0006] A second aspect of the means for solving the above problem is a light-transmitting member comprising a substrate including a resin layer and a functional film provided on the substrate, wherein the thickness of the substrate is 1 μm or more and less than 1 mm, the optical thickness of the functional film for light having a wavelength of 464 nm or more and 653 nm or less is less than half of the wavelength, the contact angle of water with the surface above the functional film on the light-transmitting member is less than 90°, the functional film has a porous portion containing a large number of particles, the distance between a first particle and a second particle among the large number of particles is smaller than the size of the first particle, and a gap is provided between the first particle and the second particle.

[0007] A third aspect of the means for solving the above problem is a translucent member comprising a substrate including a resin layer and a functional film provided on the substrate, wherein the substrate has a thickness of 1 μm or more and less than 1 mm, the physical thickness of the functional film is smaller than the thickness of the substrate, the contact angle of water with the surface above the functional film on the translucent member is less than 90°, the functional film has a porous portion containing a large number of particles, the distance between a first particle and a second particle among the large number of particles is smaller than the size of the first particle, a gap is provided between the first particle and the second particle, and each of the first particle and the second particle is a hollow particle.

[0008] A fourth aspect of the means for solving the above problem is a shield comprising: a light-transmitting member; and a holding member that holds the light-transmitting member, the holding member having a structure for fixing the light-transmitting member to a user so that the light-transmitting member covers at least a portion of the user's face, the light-transmitting member including a substrate including a resin layer and a functional film provided on the substrate, the substrate having a thickness of 1 μm or more and less than 1 mm, the functional film having a physical thickness of less than 1 μm, and the functional film including hollow particles. Effect of the Invention

[0009] According to the present invention, it is possible to provide a technique that is advantageous in improving the functionality of a light-transmitting member. [Brief description of the drawings]

[0010] [Figure 1] FIG. 4 is a schematic diagram illustrating an example of a light-transmitting member. [Diagram 2] FIG. 4 is a schematic diagram illustrating an example of a light-transmitting member. [Diagram 3] FIG. 4 is a schematic diagram illustrating the transmittance of a light-transmitting member. [Figure 4] 5A and 5B are schematic diagrams illustrating an example of a light-transmitting member and a packaging body. [Diagram 5] 5A to 5C are schematic diagrams illustrating an example of a manufacturing method of a light-transmitting member and an example of a rolled body. [Figure 6] FIG. 4 is a schematic diagram illustrating an example of a shield. [Figure 7] FIG. 4 is a schematic diagram illustrating an example of a shield. [Figure 8] FIG. 1 is a schematic diagram illustrating an example of an apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description and drawings, common reference numerals are used to designate components common to multiple drawings. In addition, common components may be described by mutually referring to multiple drawings without notice. Also, descriptions of components with common reference numerals may be omitted.

[0012] FIG. 1(a) is a perspective view of an example of a light-transmitting member 1 according to this embodiment. The light-transmitting member 1 has a film-like, sheet-like, or plate-like shape. When the light-transmitting member 1 is film-like, the light-transmitting member 1 can be called a film, when the light-transmitting member 1 is sheet-like, the light-transmitting member 1 can be called a sheet, and when the light-transmitting member 1 is plate-like, the light-transmitting member 1 can be called a plate. The light-transmitting member 1 has a front surface 110 and a back surface 120, and the front surface 110 and the back surface 120 have substantially the same shape. The distance between the front surface 110 and the back surface 120, i.e., the thickness T of the light-transmitting member 1, is much smaller than the maximum width L of the front surface 110 and the back surface 120, and for example, the thickness T can be less than 1 / 1000 of the maximum width L. The front surface 110 and the back surface 120 of the light-transmitting member 1 in this example are quadrilaterals, but are not limited thereto.

[0013] Fig. 1(b) is a cross-sectional view of the light-transmitting member 1 taken along line AB in Fig. 1(a). The light-transmitting member 1 includes a substrate 2 and a functional film 3 provided on the substrate 2. The substrate 2 may include a resin layer 11. The functional film 3 may include a porous portion 8.

[0014] The substrate 2 has two main surfaces 101 and 102 facing each other. The distance between the main surface 101 and the main surface 102 is the thickness Tb of the substrate 2. The thickness Tb of the substrate 2 can be 1 μm or more and less than 1 mm. When the thickness Tb of the substrate 2 is less than 250 μm and the light-transmitting member 1 is flexible, the light-transmitting member 1 can be said to be film-like. When the thickness Tb of the substrate 2 is 250 μm or more and the light-transmitting member 1 is flexible, the light-transmitting member 1 can be said to be sheet-like. When the light-transmitting member 1 is not flexible, the light-transmitting member 1 can be said to be plate-like.

[0015] The functional film 3 is provided on at least one of the main surfaces 101 and 102 of the substrate 2. In this example, the functional film 3 is provided on each (both surfaces) of the two main surfaces 101, 102 of the substrate 2. However, the functional film 3 may be provided only on one of the two main surfaces 101, 102 of the substrate 2. When the functional film 3 having the porous portion 8 is provided only on one surface of the light-transmitting member 1, the surface on which the functional film 3 is provided can be referred to as the front surface 110, and the surface on which the functional film 3 is not provided can be referred to as the back surface 120.

[0016] The functional film 3 on the main surface 101 has a physical film thickness Ta, and the functional film 3 on the main surface 102 has a physical film thickness Tc. The physical film thicknesses Ta and Tc of the functional film 3 are smaller than the thickness Tb of the base material 2 (Ta, Tc < Tb). Therefore, the shape and mechanical properties of the light-transmitting member 1 are mainly borne by the base material 2. The physical film thicknesses Ta and Tc of the functional film 3 may be less than 200 nm. The optical film thickness nd of the functional film 3 described later is defined by the product of the refractive index of the functional film 3 and the physical film thickness of the functional film 3. The physical film thickness Tc may be the same as or different from the physical film thickness Ta. For example, the functional film 3 on the surface 110 side (on the main surface 101) may be made thicker than the functional film 3 on the back surface 120 side (on the main surface 102).

[0017] The functional film 3 may have a porous portion 8. The porous portion 8 contains a large number of particles 4. The number of pores in the porous portion 8 correlates with the number of particles 4. The porous portion 8 has several characteristics. Fig. 2(a) is an enlarged view of an example of the porous portion 8, and as shown in the legend of Fig. 2(a), a large number (here, 10) of particles 4 are described. Pay attention to the particles 4a, 4b, and 4c among the large number of particles 4. Here, three particles 4a, 4b, and 4c will be described, but the same applies to the other particles 4. The particles 4 are preferably arranged in layers overlapping in multiple stages with respect to the main surface 101 of the base material 2.

[0018] The particle 4a has a size Da, the particle 4b has a size Db, and the particle 4c has a size Dc. Here, the sizes Da, Db, and Dc are the sizes in the film thickness direction of the functional film 3. The distance Ga between the particle 4a and the particle 4b is smaller than the size Da of the particle 4a. The distance Ga between the particle 4a and the particle 4b is smaller than the size Db of the particle 4b. Also, a gap 6 is provided between the particle 4a and the particle 4b. The particle 4a and the particle 4b may be in contact, and in that case, the distance Ga is zero.

[0019] The distance Gb between the particles 4b and 4c is smaller than the size Db of the particle 4b. The distance Gb between the particles 4b and 4c is smaller than the size Dc of the particle 4c. Furthermore, a gap 6 is provided between the particles 4b and 4c. The particles 4b and 4c may be in contact with each other, in which case the distance Gb is zero.

[0020] Furthermore, the distance Gc between the particles 4a and 4c is smaller than the size Da of the particle 4a. The distance Gc between the particles 4a and 4c is smaller than the size Dc of the particle 4c. A gap 6 is provided between the particles 4a and 4c. The particles 4a and 4c may be in contact with each other, in which case the distance Gc is zero.

[0021] In this manner, the numerous particles 4 in the porous portion 8 are in a form in which a particle 4 exists in close proximity to another particle 4, and a gap 6 exists between the two particles that exist in close proximity to each other.

[0022] The particles 4a and 4b are bound to each other by the binder 5. Furthermore, the particles 4b and 4c are bound to each other by the binder 5.

[0023] Each of the particles 4a, 4b, and 4c may contain an inorganic material. The inorganic material contained in each of the particles 4a, 4b, and 4c may be a material containing silicon and oxygen. The silicon and oxygen may form a siloxane bond. The inorganic material contained in each of the particles 4a, 4b, and 4c may be silica. Each of the particles 4a, 4b, and 4c may be a silica particle.

[0024] The binder 5 may contain an inorganic material. The inorganic material contained in the binder 5 may be a material containing silicon and oxygen. The silicon and oxygen may form a siloxane bond. The inorganic material contained in the binder 5 may be a silicate.

[0025] Since the particle 4 and the binder 5 contain an inorganic material, two particles each containing an inorganic material are bound together by the binder 5 containing an inorganic material.

[0026] In the example shown in FIG. 2(a), the particles 4 (particles 4a, 4b, 4c) may be hollow particles. That is, the particles 4 as hollow particles have a shape in which a hollow portion 42 is surrounded by a solid shell 41. The shell 41 may contain an inorganic material such as silica as described above. In another example, the particles 4 (particles 4a, 4b, 4c) may be solid particles. The particles 4 as solid particles may be composed of a uniform solid material. Alternatively, the particles 4 as solid particles may be configured to have a core-shell structure in which a solid core is surrounded by a solid shell.

[0027] The porous portion 8 may include an adhesive material 7 adhered to the particles 4. The adhesive material 7 may contain an organic material. The adhesive material 7 may be a residual organic material component contained in a coating liquid described below.

[0028] In the example shown in Fig. 2(b), the particles 4 (particles 4a, 4b, and 4c) can be chain particles. That is, the particle 4 as a chain particle has a shape in which a plurality of particles are linked together. A gap 6 is provided between two chain particles.

[0029] The light-transmitting member 1 is required to have a high light transmittance. For example, the light transmittance of the light-transmitting member 1 is preferably 95.0% or more, and more preferably 99.0% or more. For example, the average transmittance of the light-transmitting member 1 in the wavelength range of 400 nm or more and 700 nm or less is preferably 95.0% or more, and more preferably 99.0% or more. Furthermore, the transmittance at all wavelengths in the wavelength range of 400 nm or more and 700 nm or less is also preferably 95.0% or more, and more preferably 99.0% or more.

[0030] FIG. 3(a) shows an example of a schematic relationship between the optical thickness of the functional film 3 and the transmittance of the light-transmitting member 1 for light of wavelength λ. When the optical thickness nd is an even multiple of λ / 4 (nd=λ / 2, λ, 3λ / 2λ), the transmittance can be the same as when the functional film 3 is not provided (nd=0). When the optical thickness nd is an odd multiple of λ / 4 (nd=λ / 4, 3λ / 4, 5λ / 4, 7λ / 4), the transmittance for light of wavelength λ can be increased as much as possible. However, the model shown in FIG. 3(a) does not take into account the absorption and scattering of light in the functional film 3, and in reality, the thicker the functional film 3 is, the greater the absorption and scattering of light in the functional film 3 of the light-transmitting member 1 becomes, which can cause the transmittance to decrease. Therefore, it is preferable that the functional film 3 is thinner. When the wavelength of the light to be measured for transmittance is λ, it is preferable that the optical thickness nd of the functional film 3 is less than half the wavelength λ (nd<λ / 2). If the optical thickness nd is less than λ / 2, the transmittance can be increased by providing the functional film 3. In particular, the optical thickness nd of the functional film 3 is preferably not less than λ / 8 and not more than 3λ / 8 of the wavelength λ.

[0031] Next, the wavelength λ will be described. The wavelength λ is preferably 464 nm or more and 653 nm or less. This is because the standard luminosity of photopic vision for light of 464 nm or more and 653 nm or less is 0.1 or more. By increasing the transmittance for light of a wavelength where the standard luminosity of photopic vision is 0.1 or more, it is possible to suppress humans from recognizing reflected light. The wavelength λ is more preferably 509 nm or more and 614 nm or less. This is because the standard luminosity of photopic vision for light of 509 nm or more and 614 nm or less is 0.5 or more. By increasing the transmittance for light of a wavelength where the standard luminosity of photopic vision is 0.5 or more, it is possible to more effectively suppress humans from recognizing reflected light. In the example of FIG. 3(a), the wavelength λ is set to 555 nm. This is because the wavelength λ at which the standard luminosity becomes 1.0, which is the highest value, is 555 nm.

[0032] FIG. 3(b) shows an example of a schematic relationship between the transmittance of the light-transmitting member 1 and light of various wavelengths. In the example of FIG. 3(b), the refractive index of the functional film 3 is 1.22 (the square root of the refractive index of the substrate 2), the physical thickness of the functional film 3 is 105 nm, and the optical thickness of the functional film 3 is 128 nm. In this case, the transmittance is highest for light of a wavelength of 512 nm among visible light. In other words, this is the same as the wavelength λ being 512 nm. In the example of FIG. 3(b), the transmittance for all wavelengths in the wavelength range of 400 nm or more and 700 nm or less is 99.0% or more. Therefore, it is possible to obtain a light-transmitting member 1 in which the reflected component of visible light is difficult for humans to recognize.

[0033] In the example of Fig. 3(b), the transmittance for near ultraviolet rays (200-380 nm) is lower than the transmittance for visible light (400-700 nm). Such transmittance characteristics provide a UV blocking effect, and when used in a face shield as described below, it can provide a sunburn prevention effect.

[0034] FIG. 3(c) also shows an example of a schematic relationship between the transmittance of the light-transmitting member 1 and light of various wavelengths. In the example of FIG. 3(b), the refractive index of the functional film 3 is 1.22 (the square root of the refractive index of the substrate 2), the physical thickness of the functional film 3 is 1023 nm, and the optical thickness of the functional film 3 is 1248 nm. In this case, the transmittance is highest for light of a wavelength of 555 nm among visible light. In other words, this means that the wavelength λ is 555 nm and the optical thickness nd is 9λ / 4. As can be seen from FIG. 3(c), the transmittance varies greatly depending on the wavelength in the wavelength range of 400 nm or more and 700 nm or less, and the average transmittance does not exceed 99.0% as in FIG. 3(b). From a comparison between FIG. 3(b) and FIG. 3(c), it can be seen that the optical thickness nd of the functional film 3 is preferably less than half the wavelength λ (nd<λ / 2).

[0035] The refractive index of the functional film 3 is preferably lower than that of the substrate 2. Assuming that the medium on the functional film 3 is air with a refractive index of 1.0, the functional film 3 can function as an anti-reflection film that suppresses the reflection of light between the medium and the substrate 2. The closer the refractive index of the functional film 3 is to the square root of the refractive index of the substrate 2, the better the anti-reflection effect. The typical refractive index of the substrate 2 having the resin layer 11 is 1.45 to 1.65. Therefore, the refractive index of the functional film 3 is preferably 1.20 or more and 1.30 or less, and more preferably 1.20 or more and 1.24 or less. If the ratio of the voids 6 contained in the porous portion 8 is high, the refractive index of the functional film 3 may be less than 1.20. However, if the ratio of the voids 6 contained in the porous portion 8 is high, the wear resistance of the functional film 3 8 may be insufficient. If the refractive index exceeds 1.30, the anti-reflection effect between the medium (air) and the substrate 2 may not be sufficiently obtained.

[0036] The contact angle of water with respect to the surface 110 on the functional film 3 of the light-transmitting member 1 is preferably less than 90°. The same applies to the back surface 120. If the contact angle of water is less than 90°, the functional film 3 is hydrophilic, so that water droplets attached to the surface 110 can be made difficult to see. In addition, fogging caused by fine water droplets can be suppressed, and an anti-fogging effect can be provided. In order to realize such a function, the contact angle of water with respect to the surface 110 on the functional film 3 is preferably 60° or less, more preferably 45° or less, and even more preferably 30° or less. When the particles 4 are weakly bonded to each other and the abrasion resistance of the porous portion 8 is insufficient, the contact angle of water tends to exceed 45°. Specifically, it can be defined as the contact angle of pure water at room temperature of 23°C and humidity of 40 to 45% RH. The contact angle of water is preferably 3° or more, and more preferably 5° or more. If the contact angle of water is less than 3°, moisture and the like easily enters the functional film 3 from the surface 110 or back surface 120 of the functional film 3, and environmental stability may decrease.

[0037] The thickness Ta of the porous portion 8 is larger than the sum of the size Da of the particle 4a and the size Db of the particle 4b (Ta>Da+Db). In this example, three particles 4a, 4b, and 4c are overlapped in the thickness direction of the functional film 3, but since the centers of the particles are offset, the thickness Ta of the porous portion 8 is smaller than the sum of the size Da of the particle 4a, the size Db of the particle 4b, and the size Dc of the particle 4c (Ta <Da+Db+Dc)。

[0038] The size Da of the particle 4a, the size Db of the particle 4b, and the size Dc of the particle 4c are, for example, 1 nm or more, for example, 10 nm or more. The size Da of the particle 4a, the size Db of the particle 4b, and the size Dc of the particle 4c are, for example, less than 1 μm, for example, less than 500 nm, for example, less than 300 nm, for example, less than 100 nm. The size of the gap 6 between the particles 4 becomes smaller as the size of the particle 4 becomes smaller. The larger the gap 6 between the particles 4, the lower the refractive index of the porous portion 8 and the functional film 3 can be. On the other hand, the smaller the size of the particle 4, the smaller the height difference of the surface of the porous portion 8 and the functional film 3. If the height difference of the surface of the functional film 3 is small, the scattering of light on the surface of the functional film 3 can be suppressed.

[0039] Incidentally, the size of bacteria is about 1 to 5 μm. If bacteria adhere to the light-transmitting member 1, the bacteria may grow on the light-transmitting member 1. If the size of the particles 4 is less than 1 μm, the size of the voids 6 and the height difference on the surface of the functional film 3 can be reduced to a level sufficient to suppress the growth of bacteria in or on the porous portion 8 (on the functional film 3).

[0040] Moreover, the size of the virus is about 20 to 300 nm. If the virus adheres to the light-transmitting member 1, the virus may be carried on the light-transmitting member 1. If the size of the particles 4 is about the same as or smaller than the size of the virus, the size of the voids 6 and the height difference on the surface of the functional film 3 can be reduced to a level sufficient to suppress the carrying of the virus on the light-transmitting member 1. For example, the size of coronaviruses such as COVID-19 and influenza viruses is about 100 nm. If the size of the particles 4 is smaller than the size of these viruses (less than 100 nm), the size of the voids 6 and the height difference on the surface of the functional film 3 can be reduced to a level sufficient to suppress the carrying of these viruses on the light-transmitting member 1. Therefore, it is preferable that the size Da of the particles 4a, the size Db of the particles 4b, and the size Dc of the particles 4c are smaller than the size of coronaviruses such as COVID-19 and influenza viruses.

[0041] Providing the functional film 3 can provide the light-transmitting member 1 with an antistatic function. For example, when the particles 4 and the binder 5 contain an inorganic material having a siloxane bond, the hydroxyl groups present on the solid surface of the porous portion 8 adsorb moisture in the air. This reduces the electrical resistance, and suppresses the charging of the front surface 110 and the back surface 120 of the light-transmitting member 1. This can reduce foreign matter such as dust that adheres to the light-transmitting member 1 due to static electricity.

[0042] The resin layer 11 of the base material 2 of the light-transmitting member 1 is not particularly limited as long as it has excellent processability and transparency for ensuring visibility. Specific examples of resins include polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polycarbonate (PC) resin, triacetate cellulose (TAC) resin, cycloolefin (COP) resin, polymethyl methacrylate (PMMA) resin, and acrylic polyvinyl alcohol (PVA) resin. Of these, a non-crystalline resin having excellent transparency and adhesiveness can be adopted as the resin constituting the resin layer 11 of the base material 2. However, the functional film 3 of this embodiment can achieve sufficient functionality even if the base material 2 is a crystalline resin, because it can improve the transmittance and follow the flexibility of the base material 2. Since a crystalline resin has excellent chemical resistance compared to an amorphous resin, the formation of the functional film 3 is less likely to be restricted. The main crystalline resins are PE (polyethylene), PP (polypropylene), PA (polyamide), POM (polyacetal, polyoxymethylene), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), PPS (polyphenylene sulfide), PEEK (polyether ether ketone), LCP (liquid crystal polymer), and PTFE (polytetrafluoroethylene). Polycarbonate (PC) resin and polymethyl methacrylate (PMMA) resin are amorphous resins. Polyester resin is suitable for the resin layer 11, and polyethylene terephthalate (PET) is particularly preferable.

[0043] Moreover, it is more preferable that the resin layer 11 does not contain particles in the raw material. By designing the raw material to contain no particles, scattering due to raw material particles in the resin layer 11 can be reduced, and a substrate 2 with high light transmittance and excellent visibility can be provided.

[0044] The distance between the resin layer 11 and the porous portion 8 is smaller than the thickness Ta of the porous portion 8. The substrate 2 may have other layers in addition to the resin layer 11. The distance between the resin layer 11 and the porous portion 8 may be zero, but in the example of FIG. 1(b), an intermediate layer 12 is provided between the resin layer 11 and the porous portion 8. The intermediate layer 12 has a function of improving the adhesiveness between the substrate 2 and the functional film 3. The thicknesses Te and Tf of the intermediate layer 12 may be smaller than the thicknesses Ta and Tc of the functional film 3 thereon (Te < Ta, Tf < Tc). Also, the thicknesses Te and Tf of the intermediate layer 12 may be smaller than the thickness Td of the resin layer 11 therebelow (Te < Td, Tf < Td). The thicknesses Te and Tf of the intermediate layer 12 can be from 1 nm to 100 nm. In addition, for the purpose of improving the adhesion to the functional film 3, it is preferable to perform an easy adhesion treatment, UV ozone, plasma, corona treatment, etc. on the main surfaces 101 and 102 of the substrate 2.

[0045] In the example of FIG. 1(c), a hard coat layer 13 is provided between the resin layer 11 and the intermediate layer 12. The thickness of the hard coat layer 13 may be smaller than the thickness Td of the resin layer 11 therebelow. A typical hard coat layer can be a resin layer. The thickness of the substrate 2 is 1 μm or more and less than 1 mm. If the thickness of the substrate 2 is less than 1 μm, the film forming property of the functional film 3 may deteriorate. Making the thickness of the substrate 2 thinner is advantageous for improving the light transmittance of the light transmissive member 1. If the thickness of the substrate 2 is 1 mm or more, the processability such as cutting of the substrate 2 deteriorates. The thickness of the substrate 2 is preferably 100 μm or more and less than 250 μm.

[0046] In the example of FIG. 1(c), the functional film 3 includes a protective layer 14 covering the porous portion 8. The functional film 3 may realize a desired function only by the porous portion 8, but a function may be added by the protective layer 14. The protective layer 14 may function, for example, as a particle fixing layer that suppresses the particles 4 from falling off the porous portion 8. The protective layer 14 may also function as a hard coat layer that suppresses the light-transmitting member 1 from being scratched. The protective layer 14 may be a conductive layer for imparting conductivity to the surface of the functional film 3, and in that case, the protective layer 14 can impart a charge suppression function to the light-transmitting member 1. The protective layer 14 may have, for example, a function of increasing the hydrophilicity or hydrophobicity of the functional film 3. For example, when imparting hydrophilicity to the functional film 3, if the contact angle of water is 45° to 90° with only the porous portion 8, the hydrophilic protective layer 14 may be added to the functional film 3 to make the contact angle of water on the surface 110 of the light-transmitting member 1 45° or less.

[0047] FIG. 4(a) shows an example of the shape of light-transmitting member 1. The maximum width of light-transmitting member 1 in FIG. 4(a) is 2 cm or more and 2 m or less. The maximum width of light-transmitting member 1 may be 10 cm to 1 m, or may be 20 to 50 cm or less. At least one of notch 91 and hole 92 is provided in light-transmitting member 1. Notch 91 and hole 92 are used to hold light-transmitting member 1. Since notch 91 and hole 92 are used to hold light-transmitting member 1, replacement of light-transmitting member 1 can be facilitated.

[0048] The outer periphery of the light-transmitting member 1 includes a curved portion 93 having a radius of curvature r of 1 mm or more. By providing the curved portion 93, the possibility that the outer periphery of the light-transmitting member 1 will scratch other objects can be reduced.

[0049] FIG. 4 shows an example of a package 90. The package 90 includes at least three (five in this example) light-transmitting members 1 that overlap each other, and a package 94 that wraps the at least three (five in this example) light-transmitting members 1. When the package 90 is prepared, the light-transmitting members 1 that are less likely to deteriorate can be used at least three times. A used light-transmitting member 1 can also be replaced with a light-transmitting member 1 that is less likely to deteriorate. Since the functional film 3 of the light-transmitting member 1 in which the particles 4 are bound by the binder 5 has sufficient strength, damage to the functional film 3 of the light-transmitting member 1 sandwiched between two light-transmitting members 1 is suppressed. Furthermore, if an antistatic function is imparted to the functional film 3, it is possible to suppress the overlapping light-transmitting members 1 from being attracted to each other by static electricity, making it easier to remove the light-transmitting member 1 from the package 94.

[0050] The manufacturing method of the light-transmitting member 1 includes a step of applying a coating liquid that forms a porous portion 8 onto a substrate 2 to form a coating film, and a step of drying and / or baking the substrate 2 on which the coating film has been formed to form the porous portion 8.

[0051] Examples of methods for applying the coating liquid include gravure coating, die coating, spin coating, blade coating, roll coating, slit coating, printing, and dip coating. When manufacturing a light-transmitting member having a three-dimensionally complicated shape such as a concave surface and a thin film, gravure coating is preferred from the viewpoints of coating on a large area and uniformity of film thickness. More preferred is microgravure coating, which allows for the formation of a thin film on the order of 100 nm. In particular, roll-to-roll microgravure coating is preferred for coating on a long roll-shaped film.

[0052] To form the porous portion 8, the coating liquid is applied onto the substrate 2, and dried and / or cured. The drying and / or curing is a process for removing the solvent and depositing the particles 4 while bonding them together without disturbing their alignment to form the porous portion 8. The temperature for drying and / or curing depends on the heat resistance temperature of the substrate 2, but is preferably 20° C. or higher and 200° C. or lower. The time for drying and / or curing may be any time that does not affect the substrate 2 and allows the organic solvent in the layer to evaporate, but is preferably 10 minutes to 200 hours, more preferably 30 minutes to 24 hours.

[0053] In order to obtain a porous portion 8 in which the particles 4 are highly aligned, it is preferable that the alignment of the particles 4 is well-ordered. The difference in the alignment of the particles 4 mainly depends on the dispersion state of the particles 4 in the coating liquid that forms the porous portion 8 and the dispersion state of the particles 4 during the formation of the coating film.

[0054] The particles 4 are easily aligned when they are sufficiently dispersed in the coating liquid without being affected by the dispersion medium or binder 5. However, when the particles 4 are dispersed in a slightly aggregated state due to the influence of the dispersion medium or binder 5, the alignment property decreases.

[0055] In addition, the volatilization and drying of the solvent when the coating liquid is applied to the substrate 2 and the flow of the particles 4 due to concentration also greatly affect the alignment. Even if the dispersion state of the particles 4 in the coating liquid is good, if the particles 4 aggregate during drying to form the coating film, the alignment of the particles 4 will be disturbed, and when the coating film is formed, the gaps between the particles 4 will become large, and the voids in the surface direction of the substrate 2 will become large. Therefore, visible light will be scattered more. In addition, if the particles 4 are not deposited in an aligned state but are formed in a shifted state, the stress distribution of the coating film will be uneven and the strength of the film will not be maintained sufficiently.

[0056] Furthermore, if the particles 4 are not well aligned, voids of several tens of nanometers in size are likely to occur, but if the particles 4 are well aligned, the gaps 6 in the porous portion 8 become smaller, which is expected to prevent viruses from penetrating into the light-transmitting member 1. Compared to the size of bacteria, the size of a virus is about 1 / 1000, or several tens of nanometers. Furthermore, if the light-transmitting member 1 is hydrophilic, it is expected that even if a virus adheres to it, it can be easily washed away with water.

[0057] As described above, by using particles 4 to which a surface treatment agent has been added, the porous portion 8 can form a coating film in a state in which the particles 4 are aligned and deposited without disturbing their alignment.

[0058] The surface treatment agent contained in the porous portion 8 can be determined by elemental analysis of the particles 4 and the porous portion 8, or by separation and quantitative analysis such as ion exclusion chromatography.

[0059] Examples of the shape of the particle 4 include a perfect sphere, a cocoon shape, a bale shape, a disk shape, a rod shape, a needle shape, a square shape, a chain shape, etc. Among these, the particle 4 is preferably a hollow particle having a hollow part inside a spherical shell, or a chain particle which is a linked body of hydrophilic particles.

[0060] The hollow particles can reduce the refractive index of the porous portion 8 by the gas (refractive index 1.0) contained in the hollow portion. The hollow portion may be either single-hole or multi-hole, and can be appropriately selected. The hollow particles can be produced by, for example, the methods described in JP-A-2001-233611 and JP-A-2008-139581. The hollow particles can reduce the refractive index of a layer formed by stacking multiple layers of particles 4 aligned in a direction parallel to the surface of the substrate 2.

[0061] An inorganic material such as silicate is suitable for the binder 5. Since the binder 5 does not substantially contain a resin that is an organic polymer, and the particles 4 of an inorganic material (silica) are bound by the binder 5 such as an inorganic material (silicate), it is possible to form the porous portion 8 that has a low refractive index and high strength.

[0062] According to this manufacturing method, it is possible to manufacture a light-transmitting member 1 having excellent visibility with little influence of reflection and reflection while maintaining a low refractive index. The porous portion 8 of the light-transmitting member 1 is uniformly coated with a dispersion liquid of silica particles to realize a functional film 3 with a low refractive index. Since the voids 6 in the porous portion 8 and the inside of the particles 4 are present, the porous portion 8 has a characteristic of having a low refractive index. In addition, when a binder 5 made of an inorganic material is used to bind the particles 4 together, the refractive index can be lowered compared to the porous portion 8 using a binder 5 made of a resin material. When a binder 5 made of a resin material (binder resin) is used, if the porous portion 8 contains a large amount of resin, the refractive index of the functional film 3 increases and the reflection increases. In addition, when the organic solvent in the coating composition evaporates, the particles 4 are bound to the binder resin, so that the particles 4 are likely to aggregate. In addition, since the organic solvent in the coating composition evaporates faster on the surface side of the coating film, the formation of unevenness of the particles 4 on the surface of the coating film where drying proceeds quickly can be suppressed, but the arrangement of the particles 4 inside the coating film may be reduced. Therefore, when a binder resin is used, it becomes difficult to further improve anti-reflection and transparency, and there is a problem that sufficient visibility cannot be ensured due to the influence of reflection and glare from external light such as fluorescent lights.

[0063] Furthermore, by providing the functional film 3 with a low refractive index on both sides of the base material 2, it is possible to offset scattering from the main surfaces 101 and 102 of the base material 2. When the light-transmitting member 1 is used, visibility can be improved over a wide range of the field of view. Therefore, it is possible to provide a light-transmitting member that has a better anti-reflection function and high transparency and is excellent in visibility.

[0064] FIG. 5(a) is a schematic diagram for explaining an example of a method for producing a light-transmitting member 1. FIG. 5(a) is a schematic diagram for explaining a manufacturing method using a film-forming apparatus 50 by a roll to roll method as an example of a method for producing a light-transmitting member 1. A roll (roll) R1 on which a substrate 2 is wound is prepared. Then, the roll R1 is placed in an unwinding section 51 of the film-forming apparatus 50. In step S1, the unwinding section 51 unwinds the substrate 2 from the roll R1 and spreads it to a coating section 52 of the film-forming apparatus 50. In step S2, a coating liquid is applied onto the spread substrate 2 by a roll coater of the coating section 52. The roll coater is, for example, a gravure coater, a reverse coater, a slot die coater, a lip coater, a blade coater, a bar coater, an air knife coater, or the like. In step S3, the substrate 2 is sent from the coating section 52 to the drying section 53 of the film-forming apparatus 50, and the coating film is dried by a heater of the drying section 53. In this manner, the functional film 3 is formed by a wet film formation method on the developed substrate 2. In step S4, the substrate 2 on which the functional film 3 has been formed is sent from the drying section 53 to the winding section 54 of the film formation device 50, and is wound up by the winding section 54, thereby obtaining a wound body R2 (roll) of the light-transmitting member 1.

[0065] FIG. 5(b) is a schematic diagram for explaining an example of a winding body (roll). The winding body 55 includes a light-transmitting member 1 and a core material 56. The length of the long side of the light-transmitting member 1 is 10 m or more, and the light-transmitting member 1 is wound around the core material 56. The length W of the short side of the light-transmitting member 1 may be 2 m or less, or may be 20 cm or more. Such a winding body 55 is advantageous in distributing a large-area light-transmitting member 1. In addition, by developing and cutting the light-transmitting member 1 of such a winding body 55, it is possible to mass-produce light-transmitting members 1 having a maximum width L of 2 cm or more and 2 m or less, as shown in FIG. 4(a).

[0066] The light-transmitting member 1 can be used in a shield. Due to the impact of the novel coronavirus (COVID-19), there is an increasing demand for shields such as shield partitions and face shields aimed at preventing the spread of infection. In particular, medical institutions are seeking highly transparent, low-reflection face shields with excellent visibility from the standpoint of strengthening infection control measures and providing advanced medical care, and there is a demand for improving the functionality of light-transmitting members that use resin substrates.

[0067] FIG. 6(a) is a schematic diagram for explaining a shield partition 60a as an example of a shield. The shield partition 60a includes a light-transmitting member 1 and a holding member 63 for holding the light-transmitting member 1. The holding member 63 includes a fixing portion 61 to which the light-transmitting member 1 is fixed, and a support portion 62 for stably installing the fixing portion 61 on a ground surface. The support portion 62 is coupled to the fixing portion 61. The fixing portion 61 is frame-shaped with an opening, and the light-transmitting member 1 is placed in the opening. The peripheral portion of the light-transmitting member 1 is fixed to the fixing portion 61 by a fixing part 64 such as a pin or a screw. The fixing part 64 can pass through the notch 91 or the hole 92 shown in FIG. 4(a). The support portion 62 serves as a leg to support the fixing portion 61. The shield partition 60a can be placed on, for example, a table or a counter. The shield partition 60a may be provided with a ventilation fan for ventilating the atmosphere adjacent to the light-transmitting member 1.

[0068] FIG. 6(b) is a schematic diagram for explaining a face shield 60b as an example of a shield. The face shield 60b includes a light-transmitting member 1 and a holding member 65 for holding the light-transmitting member 1. The holding member 65 has a structure for fixing the light-transmitting member 1 to a user so that the light-transmitting member 1 covers at least a part of the user's face. The holding member 65 includes a fixing portion 65 to which the light-transmitting member 1 is fixed, and a support portion 66 for fixing the fixing portion 65 to the user. The support portion 62 is coupled to the fixing portion 61. The fixing portion 65 is rod-shaped, and the peripheral portion of the light-transmitting member 1 is fixed to the fixing portion 61 by a fixing part 69 such as a pin or a screw on the side surface of the fixing portion 65. The fixing part 64 can pass through the notch 91 or the hole 92 shown in FIG. 4(a). The belt-shaped support portion 62 is worn by the wearer and supports the fixing portion 61. The light-transmitting member 1 of the face shield 60b covers, for example, at least any of the eyes, nose, and mouth of the user, and preferably all of them.

[0069] The surface of the light-transmitting member 1 may have a curved surface. The curved surface of the light-transmitting member 1 is preferably formed along the face surface, and the radius of curvature of the curved surface is preferably 10 cm or more. The outer surface (surface opposite to the face side) of the light-transmitting member 1 in the face shield 60b can be the front surface 110, and the inner surface (surface on the face side) can be the back surface 120. It is preferable to provide the functional film 3 on both sides of the light-transmitting member 1. When using the face shield 60b, the outer surface is more likely to be scratched than the inner surface. Therefore, in consideration of the scratch resistance of the light-transmitting member 1, it is also effective to make the functional film 3 on the outer surface side thicker than the functional film 3 on the inner surface side. When the functional film 3 is provided only on one side (surface 110) of the light-transmitting member 1, the surface 110 of the functional film 3 may be the inner surface (surface on the face side) or the surface 110 of the functional film 3 may be the outer surface (surface opposite to the face side). When an anti-fogging function due to the hydrophilicity of the functional film 3 is expected, it is preferable to provide the functional film 3 on the inner surface side. When the anti-reflection effect of the functional film 3 is expected, it is preferable to provide the functional film 3 on the outer surface side, since the light source on the outer surface side can be the main cause of reflected light.

[0070] The face shield 60b may be provided with a ventilation fan 68 for ventilating the atmosphere adjacent to the light-transmitting member 1. In this example, the ventilation fan 68 is provided inside the holding member 65 (fixing portion 61). A wearer wearing such a face shield 60b may be in charge of observing a product and / or a manufacturing device through the light-transmitting member 1 in the manufacture of an article. According to such a manufacturing method of an article, not only is the face of the wearer protected by the use of the face shield 60b, but the excellent visibility of the light-transmitting member 1 can improve the quality of the article and work efficiency.

[0071] FIG. 7 shows a video (photograph) produced by attaching a face shield 60a as shown in FIG. 6(b) to a subject 70 simulating a head and photographing the subject 70 through a light-transmitting member 1. The face shield 60a worn on the subject 70 in the left half X of the photograph in FIG. 7 uses a light-transmitting member 1 having a functional film 3 on a substrate 2. The face shield 60a worn on the subject 70 in the right half Y of the photograph in FIG. 7 uses a substrate 2 without a functional film 3. The tip of the arrow in FIG. 7 points to the outer periphery of the light-transmitting member 1 or substrate 2. In this way, the video produced by photographing the subject 70 through the light-transmitting member 1 can express the subject 70 well. Therefore, according to such a video production method, a high-quality video can be produced, and the high-quality video can be distributed, broadcast, and distributed to increase the satisfaction of viewers.

[0072] From one side of a shield such as the shield partition 60a or the face shield 60b, the opposite side of the shield can be seen through the light-transmitting member 1. By making the light-transmitting member 1 have a configuration with increased transmittance, it is possible to suppress the occurrence of reflected light at the light-transmitting member 1, and visibility is improved. In addition, by making the light-transmitting member 1 have a configuration with increased hydrophilicity, it is possible to reduce fogging due to water vapor, and visibility is improved. In addition, even if splashes such as water droplets adhere to the light-transmitting member 1, the visibility of the water droplets can be reduced.

[0073] The user of the shield (wearer) can view the scenery through the light-transmitting member 1, and observers other than the wearer can observe the face of the user through the light-transmitting member 1. In this case, the light-transmitting member 1 has a configuration with high transmittance, so that the occurrence of reflected light at the light-transmitting member 1 can be suppressed, and visibility can be improved. Therefore, by providing the functional film 3 with high hydrophilicity on the face side of the light-transmitting member 1, it is possible to reduce fogging caused by the wearer's breath, and to suppress the decrease in visibility due to fogging. Even if water droplets from splashes emitted by the wearer adhere to the face side of the light-transmitting member 1, the wettability of the water droplets reduces the visibility of the water droplets from observers other than the wearer, so that the discomfort felt by the observer can be reduced. By providing the functional film 3 with high hydrophilicity on the side opposite to the face of the light-transmitting member 1, it is possible to suppress the decrease in visibility due to the water droplets, even if splashes (rain, etc.) on the wearer adhere to the light-transmitting member 1.

[0074] In this way, by using a shield equipped with a light-transmitting member 1, it is possible to achieve a purpose other than the purpose of ending the spread of infectious diseases.

[0075] FIG. 8(a) shows an imaging device 20a as an example of a device including a light-transmitting member 1. The imaging device 20a includes a main body 21 that houses an imaging unit 22. The imaging device 20a includes a light-transmitting part 23 in front of the imaging unit 22. The light-transmitting part 23 is fixed to the main body 21. The light-transmitting part 23 is a cover made of glass, plastic, or the like. The light-transmitting member 1 is attached to the outer surface of the light-transmitting part 23. A functional film 3 having a porous part 8 is provided only on one main surface of the base material 2 of the light-transmitting member 1, and a functional film 3 having a porous part 8 is not provided on the other main surface of the base material 2. An adhesive layer for attaching the base material 2 to the light-transmitting part 23 is provided on the other main surface of the base material 2. The functional film 3 provided on the light-transmitting member 1 can provide the imaging device 20a with functionality such as anti-reflection, anti-static, anti-fogging, and anti-drip. Furthermore, if the deteriorated light-transmitting member 1 can be replaced with a light-transmitting member 1 with less deterioration, the performance of the imaging device 20a can be maintained for a long period of time.

[0076] FIG. 8(b) shows a display device 20b as an example of a device including a light-transmitting member 1. The imaging device 20b includes a main body 21 that houses a display unit 24. The display unit 24 can be a display device or a printed matter. The image capturing device 20b includes a light-transmitting part 23 in front of the display unit 24. The light-transmitting part 23 is fixed to the main body 21. The light-transmitting part 23 is a cover made of glass, plastic, or the like. The light-transmitting member 1 is attached to the outer surface of the light-transmitting part 23. A functional film 3 having a porous part 8 is provided on both of the two main surfaces of the base material 2 of the light-transmitting member 1. An adhesive layer 15 for attaching the base material 2 to the light-transmitting part 23 is provided on the other main surface of the base material 2. In order to increase the adhesion between the adhesive layer 15 and the base material 2, the functional film 3 is not provided between at least a part of the adhesive layer 15 and the base material 2. In this way, the functional film 3 does not need to be provided on the entire main surface of the base material 2, and the functional film 3 may be patterned on the base material 2. The functional film 3 provided on the light-transmitting member 1 can provide the imaging device 20a with functions such as anti-reflection, anti-static, anti-glare, anti-fogging, and anti-drip. Furthermore, if the deteriorated light-transmitting member 1 can be replaced with a light-transmitting member 1 with less deterioration, the display quality of the display device 20b can be maintained for a long period of time. EXAMPLES

[0077] [Example 1] The light-transmitting member was prepared as follows.

[0078] ● Preparation of coating liquid for forming functional film: A coating liquid for forming a functional film was prepared by blending the following components. 1-ethoxy-2-propanol (hereinafter abbreviated as 1E2P) was added to 580 g of an isopropyl alcohol dispersion of hollow silicon oxide particles (Suluria 1110 manufactured by JGC Catalysts and Chemicals Co., Ltd., average particle size about 50 nm, shell thickness about 10 nm, solid content concentration 20.5 mass%), while heating and distilling off isopropyl alcohol. Isopropyl alcohol was distilled off until the solid content concentration reached 19.5 mass%, and 610 g of 1E2P solvent replacement liquid of hollow silicon oxide particles (hereinafter referred to as solvent replacement liquid 1) was prepared. A surface treatment agent (heptafluorobutyric acid manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the obtained solvent replacement liquid A so that the ratio of hollow silicon oxide particles: surface treatment agent was 100 / 1, and dispersion liquid B was obtained.

[0079] In a separate container, 11.4 g of 1-propoxy-2-propanol and 4.5 g of methyl polysilicate (Methyl Silicate 53A, manufactured by Colcoat Co., Ltd.) were slowly added and stirred at room temperature for 120 minutes to prepare a silica sol (hereinafter, silica sol 1).

[0080] Dispersion B was diluted with ethyl lactate to a solids concentration of 3.9% by mass, and then silica sol 1 was added so that the ratio of hollow silicon oxide particles:silica sol components was 100 / 12. The mixture was further mixed and stirred at room temperature for 2 hours to obtain coating solution C containing hollow silicon oxide particles. The viscosity of coating solution C was 2.56 mPa s.

[0081] The refractive index of the functional film was evaluated as follows. First, a functional film was formed on the polished surface of a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 1 mm, one side of which was polished), and a spectroscopic ellipsometer (VASE, manufactured by J.A. Woollam Japan) was used to measure the refractive index from 380 nm to 800 nm. The refractive index was taken as the refractive index at a wavelength of 550 nm. The refractive index was evaluated according to the following criteria. It was confirmed that the refractive index of the functional film used in this example was 1.22.

[0082] ●Functional film formation on substrate: Functional film formation on substrate was carried out as follows. The substrate was a roll of polyester film 300mm wide and 200m long (Toray: Lumirror #188-U34 surface treatment <inner surface> easy adhesion coat, surface treatment <outer surface> easy adhesion coat). The film was formed using a roll to roll coater (Labo Co., Ltd.: UVS-700) as the film forming device. The coating method used was the microgravure method, and the film forming speed was set at 2.5M / min.

[0083] First, coating solution C was prepared in the pan of the device, and a functional film was formed by adjusting the ratio of the film formation speed and the rotation speed of the microgravure roll so that the film thickness was 110 nm. After that, a functional film was formed on the opposite side under the same conditions. The drying temperature after film formation was 80°C. The obtained light-transmitting member was cut and processed into the shape shown in Figure 3.

[0084] The light-transmitting members were evaluated as follows.

[0085] ●Evaluation of transmittance of translucent materials: As a numerical value expressing the transparency of translucent materials, total light reflectance was evaluated in accordance with the former JIS-K-7105 and JIS-K-7361 (spectrophotometer U-4000: manufactured by Hitachi High-Technologies Corporation).

[0086] ●Haze evaluation of translucent materials: As an index of transparency of translucent materials, haze was evaluated in accordance with the former JIS-K-7105 and JIS-K-7136 (same as above).

[0087] ●Evaluation of reflectance of light-transmitting members: Reflectance was evaluated as an index of the transparency of light-transmitting members. In order to avoid the influence of reflection from the back surface, the back surface of the light-transmitting member to be measured was roughened with sandpaper (#800) beforehand, and then black paint was applied to block the light before evaluation (reflectance meter USPM-RU: manufactured by Olympus Corporation).

[0088] ●Evaluation of visibility of light-transmitting material: The light-transmitting material was cut and processed into the shape shown in Figure 3 to create a face shield, and the actual visibility was then confirmed. In terms of the evaluation, the presence or absence of reflections from external light such as fluorescent lights when viewed from the outside (the side not being worn) and the level of transparency when viewed from the inside (the side being worn) were evaluated in comparison with the base material itself without a functional film formed. The visibility was evaluated according to the following criteria. A: Visibility is significantly improved compared to substrates without functional films. B: Visibility is slightly improved compared to the substrate without the functional film. C: There is no significant difference in visibility compared to a substrate without a functional film.

[0089] Wiping evaluation of light-transmitting members: Wiping evaluation of light-transmitting members was performed as follows. A polyester wiper (Texwipe Alpha Wiper TX1009) was soaked in pure water and neutral detergent, and evaluation was performed under three wiping conditions, including dry wiping. Under each condition, 200 g / cm 2 After the wiper was moved back and forth on the light-transmitting member 10 times under a load of 100 mm, the wiper was visually evaluated for defects on the light-transmitting member. The wiper was evaluated according to the following criteria. A: In good condition with no scratches or peeling. B: Some scratches are visible C: Scratches are noticeable and some peeling is visible. D: The membrane has peeled off.

[0090] Evaluation of fogging due to breath: Breath was blown onto the functional film of the light-transmitting member, and the presence or absence of fogging on the light-transmitting member was evaluated visually. The fogging was evaluated according to the following criteria. A: Does not fog up B: Slightly cloudy C: Cloudy

[0091] The conditions of the light-transmitting member in Example 1 are shown in Table 1, and the evaluation results are shown in Table 2.

[0092] [Example 2] A light-transmitting member was prepared using the same coating solution C and substrate as in Example 1. Before forming the functional film, a corona discharge treatment (80 W·min / M 2 ) was performed. Then, the rotation ratio with the microgravure roll was adjusted so that the film thickness was 110 nm, and then a functional film was formed. Thereafter, the opposite surface was not subjected to corona discharge treatment, and a functional film was formed under the same conditions as in Example 1. The drying temperature after film formation was 80°C. The conditions for the light-transmitting member in Example 2 are shown in Table 1, and the evaluation results are shown in Table 2.

[0093] [Example 3] A light-transmitting member was produced using the same coating solution C and substrate as in Example 1. A functional film was formed after adjusting the rotation ratio with the microgravure roll so that the film thickness was 110 nm, and then a functional film was formed on the opposite surface so that the film thickness was 130 nm by changing the rotation ratio with the microgravure roll. The drying temperature after film formation was 80° C. The conditions for the light-transmitting member in Example 3 are shown in Table 1, and the evaluation results are shown in Table 2.

[0094] [Example 4] A light-transmitting member was produced using the same coating solution C and substrate as in Example 1. A functional film was formed after adjusting the rotation ratio with the microgravure roll so that the film thickness was 110 nm, and then a functional film was formed on the opposite surface so that the film thickness was 150 nm by changing the rotation ratio with the microgravure roll. The drying temperature after film formation was 80° C. The conditions for the light-transmitting member in Example 4 are shown in Table 1, and the evaluation results are shown in Table 2.

[0095] [Example 5] A light-transmitting member was produced using the same coating liquid C as in Example 1. The substrate was a rolled polyester film 300 mm wide and 200 m long (Toray: Lumirror #125-UH13, surface treatment <inner surface> high bending easy adhesion coat, surface treatment <outer surface> low interference easy adhesion coat). A roll-to-roll coater (Labo Co., Ltd.: UVS-700) was used as the film-forming device to form a film. The coating method was the microgravure method, and the film-forming speed was 2.5 M / min.

[0096] First, the coating solution C was prepared in the pan of the device, and the ratio of the film formation speed and the rotation speed of the microgravure roll was adjusted so that the film thickness was 110 nm, and then a functional film was formed on the opposite side under the same conditions. The drying temperature after film formation was 80° C. The conditions of the light-transmitting member in Example 5 are shown in Table 1, and the evaluation results are shown in Table 2.

[0097] [Example 6] A light-transmitting member was produced using the same coating solution C as in Example 1. The substrate was an A4-sized sheet-shaped polyester film (Toray: Lumirror #250-T60, no surface treatment <inner surface>, no surface treatment <outer surface>). The film was formed using a tabletop coater (Mitsui Electric Seiki: TC-1 type) as the film-forming device. The coating method was a bar coater method, and the film-forming speed was 2.5 M / min. After forming a functional film on one side to a film thickness of 150 nm, it was dried in a drying oven at 80°C / 5 min, and then a functional film was formed on the other side under the same conditions. The conditions of the light-transmitting member in Example 6 are shown in Table 1, and the evaluation results are shown in Table 2.

[0098] [Example 7] A light-transmitting member was produced using the same coating liquid C as in Example 1. The substrate and film-forming method were the same as in Example 6, except that UV ozone cleaning (irradiation time 15 min, irradiation distance 10 mm) was performed as a pretreatment, and a functional film was formed under the same conditions. The conditions for the light-transmitting member in Example 7 are shown in Table 1, and the evaluation results are shown in Table 2.

[0099] [Example 8] A light-transmitting member was produced using the same coating solution C as in Example 1. The substrate and film-forming method were as follows: corona discharge treatment (80 W min / M 2 ) was performed, the functional film was formed under the same conditions as in Example 6. The conditions for the light-transmitting member in Example 8 are shown in Table 1, and the evaluation results are shown in Table 2.

[0100] [Example 9] A light-transmitting member was produced using the same coating liquid C as in Example 1. The same substrate as in Example 5 was used. A functional film was formed on only one side of the substrate after adjusting the rotation ratio with the microgravure roll so that the film thickness was 110 nm. The drying temperature after film formation was 80°C. Various evaluations were performed. The conditions for the light-transmitting member of Example 9 are shown in Table 1, and the evaluation results are shown in Table 2.

[0101] [Comparative Example] The comparative light-transmitting member was prepared as follows.

[0102] Preparation of coating solution for forming functional film: Coating solution D for forming a functional film was prepared by blending the components having the following composition. The mixture was 14.3 g of an isopropyl alcohol dispersion of hollow silicon oxide particles (Sururia 1110, manufactured by JGC Catalysts and Chemicals Co., Ltd., average particle size approximately 50 nm, shell thickness approximately 10 nm, solids concentration 20.5% by mass), 2.0 g of pentaerythritol triacrylate, 0.2 g of Irgacure 907 (manufactured by Ciba Specialty Chemicals), 0.2 g of TSF4460 (product name: alkyl polyether modified silicone oil, manufactured by GE Toshiba Silicones Co., Ltd.), and 83.3 g of methi isobutyl ketone. The viscosity of the resulting coating solution D was 2.61 mPa s. The refractive index of the functional film was evaluated as follows. First, a functional film was formed on the polished surface of a glass substrate (synthetic quartz with a diameter of 30 mm and a thickness of 1 mm, one side of which was polished), and a spectroscopic ellipsometer (VASE, manufactured by J.A. Woollam Japan) was used to measure the refractive index from 380 nm to 800 nm. The refractive index was taken as the refractive index at a wavelength of 550 nm. The refractive index was evaluated according to the following criteria. The refractive index of the functional film used in the comparative example was 1.27.

[0103] ● Formation of functional film on substrate: A porous film was formed using the obtained coating liquid D. The substrate was an A4 size sheet-shaped polyester film (Toray: Lumirror #250-T60, no surface treatment <inner surface>, no surface treatment <outer surface>). The film was formed using a tabletop coater (Mitsui Electric Seiki: TC-1 type) as the film forming device. The coating method was a bar coater method, and the film forming speed was 2.5 M / min. The functional film was formed on only one side of the substrate so that the film thickness was 2000 nm. The drying temperature after film formation was 80°C / 5 min. The obtained light-transmitting member was cut and processed into the shape shown in Figure 3, and various evaluations were performed. The conditions of the light-transmitting member of the comparative example are shown in Table 1, and the evaluation results are shown in Table 2.

[0104] [Table 1]

[0105] [Table 2]

[0106] From the results in Table 2, it was confirmed that the examples were able to achieve good functionality as a face shield.

[0107] The above-described embodiments can be appropriately modified without departing from the technical concept. The disclosure of this specification includes not only what is described in this specification, but also all matters that can be understood from this specification and the drawings attached to this specification.

[0108] In addition, in the specific numerical ranges shown as examples, the description e to f (e and f are numbers) means e or more and / or f or less. In addition, in the specific numerical ranges shown as examples, when a range of i to j and a range of m to n are both shown (i, j, m, and n are numbers), the pair of lower limit and upper limit is not limited to the pair of i and j or the pair of m and n. For example, a combination of the lower limit and upper limit of multiple pairs may be considered. In other words, when a range of i to j and a range of m to n are both shown, the range of i to n may be considered, or the range of m to j may be considered.

[0109] Furthermore, the disclosure of this specification includes the complement of each concept described in this specification. In other words, if this specification contains a statement that "A is greater than B," for example, even if the statement that "A is not greater than B" is omitted, this specification can be said to disclose that "A is not greater than B." This is because when a statement that "A is greater than B" is made, it is assumed that the case in which "A is not greater than B" is taken into consideration. [Explanation of symbols]

[0110] 1. Translucent material 2 Base material 3. Functional membrane 4 particles 5. Binder 6 void 8 Porous part

Claims

1. A substrate including a resin layer; a first functional film provided on a first main surface of the substrate; A second functional film provided on a second main surface of the substrate; A light-transmitting member comprising: The thickness of the substrate is 1 μm or more and less than 1 mm, and the light-transmitting member has flexibility; the first functional film has a front surface of the light-transmitting member, and the second functional film has a rear surface of the light-transmitting member, the optical thickness of the first functional film and the optical thickness of the second functional film for light having a wavelength of 464 nm or more and 653 nm or less are less than half the wavelength, the first functional film and the second functional film have a porous portion containing a large number of particles, the porous portion is provided with at least one of voids and pores, and first particles and second particles of the large number of particles are bound to each other by a binder; each of the first particles and the second particles contains an inorganic material; a first intermediate layer is provided between the resin layer and the first functional film, the first intermediate layer being bonded to the first functional film; a second intermediate layer is provided between the resin layer and the second functional film, the second intermediate layer being adhered to the second functional film; a hard coat layer is provided between the resin layer and the first intermediate layer, A light-transmitting member, wherein the thickness of the first intermediate layer and the thickness of the second intermediate layer are 1 nm or more and smaller than the thickness of the resin layer.

2. The light-transmitting member according to claim 1 , wherein the binder contains an inorganic material.

3. 3. The translucent member according to claim 1 or 2, wherein a distance between a third particle among the numerous particles and the first particle is smaller than a size of the first particle, a gap is provided between the first particle and the third particle, and a thickness of the porous portion of the first functional film is smaller than the sum of the size of the first particle, the size of the second particle, and the size of the third particle.

4. The light-transmitting member according to claim 1 , wherein each of the first particles and the second particles is a hollow particle.

5. The light-transmitting member according to claim 1 , wherein the binder contains silicate.

6. A translucent member described in any one of claims 1 to 5, wherein the thickness of the hard coat layer is smaller than the thickness of the resin layer, and the hard coat layer is made of resin.

7. 7. The light-transmitting member according to claim 1, wherein each of the first particles and the second particles is a silica particle, the distance between the first particle and the first main surface is greater than the distance between the second particle and the first main surface, and the height difference of the surface irregularities formed according to the shape of the first particle is 10 nm or more and less than 100 nm.

8. The optically transparent member according to claim 1 , wherein the physical thickness of the first functional film and the physical thickness of the second functional film are less than 200 nm, and the physical thickness of the second functional film is different from the physical thickness of the first functional film.

9. The light-transmitting member according to claim 1 , wherein the binder does not contain a resin.

10. A translucent member described in any one of claims 1 to 9, wherein the thickness of the porous portion of the first functional film is greater than the sum of the size of the first particles and the size of the second particles.

11. The light-transmitting member according to claim 1 , wherein the first functional film is provided with hydrophobicity.

12. 12. The light-transmitting member according to claim 1, wherein the light-transmitting member has a thickness of less than 250 [mu]m, and the resin layer is made of a polyester resin, a polycarbonate resin, a triacetate cellulose resin, or a cycloolefin resin.

13. The light-transmitting member according to claim 1 , wherein the resin layer is made of a crystalline resin.

14. The light-transmitting member according to claim 1 , wherein the base material has a thickness of 100 μm or more, and the resin layer is made of a polyester resin.

15. The light-transmitting member according to claim 1 , wherein a distance between the hard coat layer and the porous portion of the first functional film is less than 200 nm.

16. The light-transmitting member according to claim 1 , wherein the first functional film includes a protection layer that covers the porous portion of the first functional film.

17. The light-transmitting member according to claim 1 , wherein each of the first particles, the second particles, and the binder contains a material containing silicon and oxygen.

18. The light-transmitting member according to claim 1 , wherein the maximum width of the light-transmitting member is 2 cm or more and 2 m or less.

19. The optically transparent member according to claim 1 , wherein the optically transparent member is provided with at least one of a notch and a hole.

20. The light-transmitting member according to claim 1 , wherein an outer periphery of the light-transmitting member includes a curved portion having a radius of curvature of 1 mm or more.

21. A package comprising at least three overlapping light-transmitting members and a package enclosing the three light-transmitting members, each of the three light-transmitting members being the light-transmitting member according to any one of claims 1 to 20.

22. A light-transmitting member according to any one of claims 1 to 16 and a core material, A winding body, characterized in that the length of a side of the translucent member is 10 m or more, and the translucent member is wound around the core material.

23. A method for producing a light-transmitting member according to any one of claims 1 to 20, comprising the steps of: preparing a roll on which the substrate is wound; The substrate of the roll is unrolled, forming the first functional film and the second functional film on the developed substrate by a wet film forming method; A manufacturing method comprising winding up the substrate on which the first functional film and the second functional film are formed.

24. A light-transmitting member according to any one of claims 1 to 20, A holding member for holding the light-transmitting member; A shield comprising:

25. 25. The shield of claim 24, wherein the retaining member has structure for securing the optically transparent member to a user such that the optically transparent member covers at least a portion of a user's face.

26. 26. The shield of claim 24 or 25, wherein the holding member has a structure for fixing the light-transmitting member to a user such that the light-transmitting member covers at least a mouth of the user, and the portion of the light-transmitting member covering at least the mouth includes the first functional film and the second functional film.

27. 27. The shield of claim 24, wherein a surface of the light-transmitting member is curved.

28. A light-transmitting member according to any one of claims 1 to 20, and a light-transmitting part covered with the light-transmitting member.

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