Reflection film

Abstract

To provide a reflection film capable of simultaneously achieving adhesion to an adhesive agent and difficulty to cause a scratch, on an external surface of a curable resin layer.SOLUTION: A reflection film 100 includes a base material film 10, a metallic reflection layer 20, and a curable resin layer 50, in this order in a reflection film thickness direction. An arithmetical average height Sa is 0.17 to 0.30 μm, inclusive, on an external surface 51 opposite to the metallic reflection layer 20 in the curable resin layer 50.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a reflective film. [Background technology]

[0002] A liquid crystal display device includes a liquid crystal panel having an image display surface, a backlight that emits light toward the back surface of the liquid crystal panel, and a housing that houses these components. The housing has a bezel portion as a frame around the image display surface. A reflective film is disposed on the inner wall surface of the bezel portion.

[0003] The reflective film comprises a base film, a metal reflective layer, and a cured resin layer as an overcoat (OC), in this order in the thickness direction. The reflective film is assembled within the bezel by bonding the OC side of the reflective film to the inner wall surface via an adhesive. Within the bezel, the reflective film reflects light from the backlight toward the LCD panel using the metal reflective layer, thereby making effective use of the light from the backlight. One known example of such a reflective film is a reflective / light-blocking adhesive tape that comprises a white resin film, a metal thin film layer, and a coating layer, in this order in the thickness direction (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-184443 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, the reflective film is bonded to the inner wall surface using an adhesive, so it needs to adhere well to the adhesive. However, an OC with too much adhesion will lack slipperiness. An OC with poor slipperiness will be more susceptible to injury when it comes into contact with surrounding components.

[0006] The present invention provides a reflective film that can achieve both adhesion to a pressure-sensitive adhesive and resistance to damage on the outer surface of the cured resin layer of the reflective film. [Means for solving the problem]

[0007] The present invention [1] is a reflective film comprising a substrate film, a metal reflective layer, and a cured resin layer in this order in the thickness direction, wherein the arithmetic mean height Sa of the outer surface of the cured resin layer on the side opposite to the metal reflective layer is 0.17 μm or more and 0.30 μm or less.

[0008] The present invention [2] is the reflective film according to the above [1], wherein the maximum height Sz of the outer surface of the cured resin layer on the side opposite to the metal reflective layer is 5.0 μm or less.

[0009] The present invention [3] is the reflective film according to the above [1], wherein the metal reflective layer is an aluminum layer.

[0010] The present invention [4] is the reflective film according to any one of the above [1] to [3], further comprising a metal oxide layer between the metal reflective layer and the cured resin layer.

[0011] The present invention [5] is the reflective film according to the above [4], wherein the metal oxide layer is an indium tin oxide layer. [Effects of the Invention]

[0012] The reflective film of the present invention comprises a substrate film, a metal reflective layer, and a cured resin layer in this order in the thickness direction, and the arithmetic mean height Sa of the outer surface of the cured resin layer opposite the metal reflective layer is 0.17 μm or more and 0.30 μm or less. Therefore, the outer surface of the cured resin layer in the reflective film can achieve both good adhesion to the pressure-sensitive adhesive and resistance to damage. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view of an embodiment of a reflective film of the present invention. [Figure 2] This shows a method for manufacturing the reflective film shown in Figure 1. Figure 2A shows a process for forming a metal reflective layer on a substrate film, Figure 2B shows a process for forming a blackened layer on the metal reflective layer, Figure 2C shows a process for forming a metal oxide layer on the blackened layer, and Figure 2D shows a process for forming a cured resin layer on the metal oxide layer. [Figure 3] 1 is a cross-sectional view of a modified example of the reflective film of the present invention, which does not have a blackening layer. [Figure 4] 1 is a cross-sectional view of another modified example of the reflective film of the present invention, which does not have a metal oxide layer. DETAILED DESCRIPTION OF THE INVENTION

[0014] <Reflective film> As shown in FIG. 1 , a reflective film 100 according to one embodiment of the present invention includes a substrate film 10, a metal reflective layer 20, a blackening layer 30, a metal oxide layer 40, and a cured resin layer 50, which are arranged in this order from one side to the other in the thickness direction of the reflective film 100. The reflective film 100 extends in a direction (plane direction) perpendicular to the thickness direction. The reflective film 100 is, for example, a reflective film that prevents light from a backlight of a liquid crystal display device from leaking out of the housing. In the following description, one side is referred to as the bottom and the other side is referred to as the top.

[0015] The thickness of the reflective film 100 is, for example, 10 μm to 500 μm. From the viewpoint of the strength of the reflective film 100, it is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 35 μm or more. From the viewpoint of handleability, it is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less.

[0016] [Base film] The base film 10 is a substrate that ensures the strength of the reflective film 100. As shown in FIG. 1, the base film 10 has a first surface 11, which is the other surface of the reflective film 100, and a second surface 12, which is one surface of the reflective film 100 in the thickness direction. The base film 10 is, for example, a flexible, transparent resin film. Examples of materials for the base film 10 include polyester resin, polyolefin resin, acrylic resin, polycarbonate resin, polyethersulfone resin, polyarylate resin, melamine resin, polyamide resin, polyimide resin, cellulose resin, and polystyrene resin. Examples of polyester resins include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Examples of polyolefin resins include polyethylene, polypropylene, and cycloolefin polymer. Examples of acrylic resins include polymethacrylate. From the viewpoints of transparency and strength, the material for the base film 10 is preferably polyester resin, more preferably PET.

[0017] The substrate film 10 is preferably a white film from the viewpoint of ensuring the light reflectivity of the substrate film 10. The white film can be obtained, for example, as a resin film blended with particles such as inorganic fillers that cause light scattering. Examples of such particles include titanium oxide, calcium carbonate, barium sulfate, silica, and talc. Preferably, at least one selected from the group consisting of titanium oxide and silica is used. These particles may be used alone or in combination of two or more. The average particle diameter (D50) of the particles is, for example, 0.05 μm or more, preferably 0.1 μm or more, and, for example, 2 μm or less, preferably 1 μm or less. The content of the particles in the substrate film 10 as a white film is, for example, 5% by mass or more, preferably 10% by mass or more, and, for example, 50% by mass or less, preferably 40% by mass or less.

[0018] The thickness of the substrate film 10 is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 35 μm or more, from the viewpoint of suppressing the penetration of water vapor into the metal reflective layer 20 and the blackened layer 30 from the substrate film 10 side of the reflective film 100 (vapor penetration suppression), and from the viewpoint of the strength of the reflective film 100. The thickness of the substrate film 10 is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less, from the viewpoint of ensuring the handleability of the substrate film 10 in a roll-to-roll system. The thickness of the substrate film 10 is preferably 20 to 300 μm, more preferably 30 to 200 μm, and even more preferably 35 to 150 μm, from the viewpoint of achieving both the above-mentioned vapor penetration suppression and strength and the above-mentioned handleability.

[0019] The first surface 11 of the substrate film 10 may be subjected to a surface modification treatment in order to ensure adhesion of the metal reflective layer 20 to the substrate film 10. Examples of surface modification treatments include corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

[0020] [Metal reflective layer] The metal reflective layer 20 is disposed on the other side of the base film 10 in the thickness direction of the reflective film 100. In this embodiment, as shown in Fig. 1 , the metal reflective layer 20 is disposed on the first surface 11 of the base film 10. That is, the metal reflective layer 20 is in contact with the first surface 11 in this embodiment.

[0021] The metal reflective layer 20 is formed from a metal having light reflectivity. Examples of metals that form the metal reflective layer 20 include aluminum (Al), silver (Ag), titanium (Ti), and alloys thereof. From the viewpoint of ensuring good light reflectivity of the metal reflective layer 20 for visible light, the metal of the metal reflective layer 20 is preferably aluminum or silver. That is, the metal reflective layer 20 is preferably an aluminum layer or a silver layer. More preferably, the metal reflective layer 20 is an aluminum layer.

[0022] The thickness of the metal reflective layer 20 is preferably 30 nm or more, more preferably 50 nm or more, even more preferably 60 nm or more, and even more preferably 70 nm or more, from the viewpoint of ensuring the light reflectivity of the metal reflective layer 20 and the reflective film 100. The thickness of the metal reflective layer 20 is preferably 500 nm or less, more preferably 250 nm or less, even more preferably 150 nm or less, and even more preferably 120 nm or less, from the viewpoint of ensuring the adhesion of the metal reflective layer 20 to the substrate film 10. The thickness of the metal reflective layer 20 is preferably 30 to 500 nm, more preferably 50 to 250 nm, even more preferably 60 to 150 nm, and even more preferably 70 to 120 nm, from the viewpoint of achieving both the above-mentioned light reflectivity and the above-mentioned adhesion.

[0023] [Blackened layer] The blackening layer 30 is disposed on the other side of the metal reflective layer 20 in the thickness direction of the reflective film 100. In this embodiment, as shown in Fig. 1, the blackening layer 30 is disposed on the metal reflective layer 20. That is, in this embodiment, the blackening layer 30 is in contact with the metal reflective layer 20.

[0024] The blackening layer 30 is a layer with high light absorption, and in this embodiment, is an inorganic blackening layer containing a metal compound and an elemental metal. The blackening layer 30 may contain multiple metal compounds. The blackening layer 30 may also contain multiple elemental metals.

[0025] A metal compound is a compound of a metal and a nonmetal. Examples of metal compounds include metal oxides, metal nitrides, and metal carbides. The metal compound is preferably a metal oxide. Examples of the metal (first metal) in the metal compound include indium (In), copper (Cu), molybdenum (Mo), and iron (Fe). The first metal is preferably at least one selected from the group consisting of In, Cu, Mo, and Fe.

[0026] Examples of the elemental metal (second metal) include In, Cu, Mo, and Fe. The elemental metal is preferably at least one selected from the group consisting of In, Cu, Mo, and Fe. When the metal compound contains multiple elemental metals, the multiple elemental metals preferably include metals different from the first metal. More preferably, the elemental metal is a metal other than the first metal.

[0027] The proportion of the first metal in the blackening layer 30 is preferably 10 atomic % or more, more preferably 20 atomic % or more, and preferably 90 atomic % or less, more preferably 80 atomic % or less, from the viewpoint of realizing high light-shielding properties in the blackening layer 30. That is, the proportion of the first metal in the blackening layer 30 is preferably 10 to 90 atomic %, more preferably 20 to 80 atomic %. The proportion of the second metal in the blackening layer 30 is preferably 10 atomic % or more, more preferably 20 atomic % or more, and preferably 90 atomic % or less, more preferably 80 atomic % or less, from the viewpoint of realizing high light-shielding properties in the blackening layer 30. That is, the proportion of the second metal in the blackening layer 30 is preferably 10 to 90 atomic %, more preferably 20 to 80 atomic %.

[0028] To achieve high light-blocking properties in the blackening layer 30, the blackening layer 30 preferably contains a metal oxide as the metal compound and an elemental metal other than the first metal, and more preferably contains indium oxide as the metal compound and copper as the elemental metal. When the blackening layer 30 contains indium oxide and copper, the proportion of In in the blackening layer 30 is preferably 40 atomic % or more, more preferably 50 atomic % or more, and preferably 90 atomic % or less, more preferably 80 atomic % or less, to achieve high light-blocking properties in the blackening layer 30. That is, the proportion of In in the blackening layer 30 is preferably 40 to 90 atomic %, more preferably 50 to 80 atomic %. When the blackening layer 30 contains indium oxide and copper, the proportion of Cu in the blackening layer 30 is preferably 5 atomic % or more, more preferably 10 atomic % or more, and preferably 50 atomic % or less, more preferably 40 atomic % or less, to achieve high light-blocking properties in the blackening layer 30. That is, the proportion of Cu in the blackened layer 30 is preferably 5 to 50 atomic %, and more preferably 10 to 40 atomic %.

[0029] The thickness of the blackening layer 30 is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more, and even more preferably 25 nm or more, from the viewpoint of ensuring the light-blocking properties of the blackening layer 30 and the reflective film 100. The thickness of the blackening layer 30 is preferably 400 nm or less, more preferably 200 nm or less, even more preferably 100 nm or less, and even more preferably 50 nm or less, from the viewpoint of ensuring the adhesion of the blackening layer 30 to the base (the metal reflective layer 20 in this embodiment). The thickness of the blackening layer 30 is preferably 5 to 400 nm, more preferably 10 to 200 nm, even more preferably 20 to 100 nm, and even more preferably 25 to 50 nm, from the viewpoint of achieving both the light-blocking properties and the adhesion.

[0030] The luminous transmittance (Y value) of the blackening layer 30 at wavelengths of 380 nm to 780 nm in the CIE-XYZ color system is preferably 0.1% or less, more preferably 0.05% or less, and even more preferably 0.03% or less, from the viewpoint of ensuring the light-blocking properties of the blackening layer 30 and the reflective film 100. The luminous transmittance is, for example, 0.001% or more, 0.005% or more, or 0.01% or more. The luminous transmittance can be measured, for example, using a spectrophotometer (product name "U-4100", manufactured by Hitachi High-Tech Science Corporation).

[0031] [Metal oxide layer] The metal oxide layer 40 is disposed on the other side of the blackening layer 30 in the thickness direction of the reflective film 100. In this embodiment, as shown in FIG. 1 , the metal oxide layer 40 is disposed on the blackening layer 30. In this embodiment, the metal oxide layer 40 is disposed between the metal reflective layer 20 and the cured resin layer 50, more specifically, between the metal reflective layer 20 and the blackening layer 30. That is, the metal oxide layer 40 is in contact with the blackening layer 30.

[0032] In this embodiment, the metal oxide layer 40 is a barrier layer. The metal oxide layer 40, for example, prevents water vapor from penetrating from the cured resin layer 50 side into the blackening layer 30 and the metal reflective layer 20. The prevention of water vapor penetration helps to prevent corrosion, such as galvanic corrosion, of the metal reflective layer 20 and the blackening layer 30.

[0033] Examples of metals in the metal oxide that form the metal oxide layer 40 include indium (In), zinc (Zn), tin (Sn), magnesium (Mg), nickel (Ni), cobalt (Co), and chromium (Cr). From the viewpoint of ensuring the water vapor barrier properties of the metal oxide layer 40, the metal in the metal oxide is preferably at least one selected from the group consisting of In, Zn, Sn, Mg, Ni, Co, and Cr, and more preferably, the metal oxide layer 40 is an indium tin oxide (ITO) layer.

[0034] The thickness of the metal oxide layer 40 is preferably 5 nm or more, more preferably 8 nm or more, and even more preferably 10 nm or more, from the viewpoint of ensuring the water vapor barrier properties of the metal oxide layer 40. The thickness of the metal oxide layer 40 is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less, from the viewpoint of ensuring the adhesion of the metal oxide layer 40 to the blackened layer 30. The thickness of the metal oxide layer 40 is preferably 5 to 200 nm, more preferably 8 to 150 nm, and even more preferably 10 to 100 nm, from the viewpoint of achieving both the water vapor barrier properties and the adhesion.

[0035] [Cured resin layer] The cured resin layer 50 is disposed on the other side of the metal oxide layer 40 in the thickness direction of the reflective film 100. In this embodiment, as shown in FIG. 1 , the cured resin layer 50 is disposed on the metal oxide layer 40. That is, in this embodiment, the cured resin layer 50 is in contact with the metal oxide layer 40. The cured resin layer 50 is an overcoat layer that serves as the outermost layer on the other side of the reflective film 100 in the thickness direction of the reflective film 100. In addition, the cured resin layer 50 is, for example, a hard coat layer that makes the reflective film 100 less susceptible to scratches.

[0036] The cured resin layer 50 is a cured product of a curable resin composition. The curable resin composition contains a curable resin. Examples of the curable resin include polyester resin, acrylic urethane resin, acrylic resin (excluding acrylic urethane resin), urethane resin (excluding acrylic urethane resin), amide resin, silicone resin, epoxy resin, and melamine resin. These curable resins may be used alone or in combination of two or more. From the viewpoint of ensuring high hardness of the cured resin layer 50, the curable resin is preferably at least one selected from the group consisting of acrylic urethane resin and acrylic resin, and more preferably acrylic urethane resin.

[0037] Examples of the curable resin include ultraviolet-curable resin and thermosetting resin. The curable resin is preferably ultraviolet-curable resin, since it can be cured without high-temperature heating and therefore helps improve the production efficiency of the reflective film 100.

[0038] The proportion of the curable resin in the cured resin layer 50 (however, this proportion in the cured resin layer 50 excluding the particles described below; the same applies hereinafter) is preferably 95.0 mass% or more, more preferably 97.0 mass% or more, and even more preferably 99.0 mass% or more, from the viewpoint of ensuring the hardness of the cured resin layer 50. The proportion of the curable resin in the cured resin layer 50 is preferably 99.9 mass% or less, more preferably 99.7 mass% or less, and even more preferably 99.5 mass% or less, from the viewpoint of ensuring the proportions of the other components in the cured resin layer 50. The proportion of the curable resin is preferably 95.0 to 99.9 mass%, more preferably 97.0 to 99.7 mass%, and even more preferably 99.0 to 99.5 mass%, from the viewpoint of both ensuring the hardness and ensuring the proportions of the other components.

[0039] The cured resin layer 50 preferably contains particles. That is, the curable resin composition preferably contains particles. By adjusting the content and / or average particle diameter (D50) of the particles contained in the cured resin layer 50, it is possible to adjust the arithmetic mean height Sa of the outer surface 51 of the cured resin layer 50. Furthermore, by adjusting the arithmetic mean height Sa of the outer surface 51 of the cured resin layer 50, it is possible to adjust the slipperiness of the outer surface 51 relative to peripheral members and the adhesion to the adhesive.

[0040] Furthermore, the maximum height Sz of outer surface 51 of cured resin layer 50 can be adjusted by adjusting the content and / or average particle diameter (D50) of the particles contained in cured resin layer 50. By adjusting the maximum height Sz of outer surface 51 of cured resin layer 50, the adhesion of outer surface 51 of cured resin layer 50 to the adhesive can be adjusted.

[0041] Examples of the particles include inorganic oxide particles and organic particles. Examples of inorganic oxide particle materials include silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide. Examples of organic particle materials include polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, and polycarbonate. The particles may be used alone or in combination of two or more. Organic particles are preferably used as the particles. Polymethacrylate particles are preferably used as the organic particles. Inorganic oxide particles may also be used. The inorganic oxide particles are preferably at least one selected from silica particles and zirconia particles.

[0042] The average particle diameter (D50) of the particles is, for example, 0.5 μm or more and 10 μm or less. The average particle diameter (D50) of the particles is preferably 1.0 μm or more, more preferably 1.5 μm or more, even more preferably 2.0 μm or more, and even more preferably 2.5 μm or more. It is preferably 6.0 μm or less, more preferably 5.0 μm or less, even more preferably 4.0 μm or less, and even more preferably 3.5 μm or less. By adjusting the average particle diameter (D50) of the particles to within the above range, the arithmetic mean height Sa and / or maximum height Sz of the outer surface 51 of the cured resin layer 50 can be adjusted to an appropriate range.

[0043] The average particle size (D50) of particles is the median size in the volume-based particle size distribution (the particle size at which the volume cumulative frequency reaches 50% from the smallest diameter side), and can be determined, for example, based on the particle size distribution obtained by laser diffraction / scattering.

[0044] The particle content in the cured resin layer 50 is, for example, 0.1 parts by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the curable resin. The particle content in the cured resin layer 50 is, relative to 100 parts by mass of the curable resin, preferably 0.3 parts by mass or more, more preferably 0.6 parts by mass or more, even more preferably 0.8 parts by mass or more, and even more preferably 0.9 parts by mass or more. The particle content is, relative to 100 parts by mass of the curable resin, preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, even more preferably 1.5 parts by mass or less, and even more preferably 1.2 parts by mass or less. By adjusting the average particle diameter (D50) of the particles within the above range, the arithmetic mean height Sa and / or maximum height Sz of the outer surface 51 of the cured resin layer 50 can be adjusted within an appropriate range.

[0045] The cured resin layer 50 may contain a leveling agent. That is, the curable resin composition may contain a leveling agent. Examples of the leveling agent include a silicone-based leveling agent, a fluorine-based leveling agent, and an acrylic-based leveling agent.

[0046] The thickness of the cured resin layer 50 is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 0.7 μm or more, and even more preferably 0.9 μm or more, from the viewpoint of imparting sufficient abrasion resistance to the cured resin layer 50. The thickness of the cured resin layer 50 is preferably 5 μm or less, more preferably 3 μm or less, even more preferably 2 μm or less, and even more preferably 1.5 μm or less, from the viewpoint of ensuring adhesion of the cured resin layer 50 to the metal oxide layer 40. The thickness of the cured resin layer 50 is preferably 0.1 to 5 μm, more preferably 0.5 to 3 μm, even more preferably 0.7 to 2 μm, and even more preferably 0.9 to 1.5 μm, from the viewpoint of achieving both the above-mentioned abrasion resistance and the above-mentioned adhesion. Note that the thickness of the cured resin layer 50 is the average thickness of the cured resin layer 50 alone, ignoring unevenness due to particles and the like.

[0047] When the cured resin layer 50 contains the above-mentioned particles, the ratio of the average particle diameter (50) of the particles to the thickness of the cured resin layer 50 (average particle diameter (50) of the particles / thickness of the cured resin layer 50) is, for example, 0.5 or more and 20 or less. From the viewpoint of reliably holding the particles in the cured resin layer 50, it is preferably 15 or less, more preferably 10 or less, and even more preferably 5 or less. From the viewpoint of the effect of adjusting the arithmetic mean height Sa of the cured resin layer 50, it is preferably 1 or more, more preferably 2 or more, and even more preferably 2.5 or more.

[0048] The cured resin layer 50 has an outer surface 51 on the side opposite to the metal reflective layer 40. The outer surface 51 is the surface exposed on the other side of the reflective film 100. The arithmetic mean height Sa of the outer surface 51 is, for example, 0.17 μm or more and 0.30 μm or less.

[0049] The arithmetic mean height Sa of the outer surface 51 is preferably 0.18 μm or more, more preferably 0.19 μm or more, and even more preferably 0.20 μm or more. By setting the arithmetic mean height Sa of the outer surface to be equal to or greater than the above-mentioned lower limit, the contact area of the outer surface 51 with the surrounding components is reduced, ensuring the slipperiness of the outer surface 51 with respect to the surrounding components. As a result, it is ensured that the outer surface 51 is less likely to be damaged. Note that the surrounding components here are components that may come into contact during assembly, such as the bezel of a liquid crystal display device.

[0050] Furthermore, the arithmetic mean height Sa of the outer surface 51 is preferably 0.28 μm or less, more preferably 0.26 μm or less, and even more preferably 0.24 μm or less. By setting the arithmetic mean height Sa of the outer surface 51 to the above upper limit or less, adhesion between the outer surface 51 and the pressure-sensitive adhesive is ensured.

[0051] Furthermore, when the cured resin layer 50 contains particles as described above, if the arithmetic mean roughness Sa is too high, the particles may fall off. The fallen particles may be present between the outer surface 51 of the cured resin layer 50 and the surrounding components, damaging the cured resin layer 50. From the viewpoint of suppressing particle fall-off, the arithmetic mean height Sa of the outer surface 51 is preferably 0.40 μm or less, more preferably 0.35 μm or less, even more preferably 0.3 μm or less, and even more preferably 0.25 μm or less.

[0052] There are no particular limitations on the method for adjusting the arithmetic mean height Sa of outer surface 51 of cured resin layer 50. In addition to the method of incorporating particles into the curable resin composition as described above, examples include a method of processing outer surface 51 of the cured resin layer before or after curing by mold transfer.

[0053] The arithmetic mean height Sa of the outer surface 51 can be measured in accordance with ISO 25178 using a shape analysis laser microscope (product name "VK-X1000", manufactured by Keyence Corporation).

[0054] The maximum height Sz of the outer surface 51 is, for example, 6.0 μm or less, preferably 5.0 μm or less, more preferably 4.5 μm or less, and even more preferably 4.0 μm or less. By setting the maximum height Sz of the outer surface 51 to the above-mentioned upper limit or less, it is possible to ensure the adhesion of the outer surface 51 to the pressure-sensitive adhesive. The lower limit of the maximum height Sz of the outer surface 51 is equal to or greater than the thickness of the cured resin layer 50, and is, for example, equal to or greater than 1.0 μm.

[0055] There are no particular limitations on the method for adjusting the maximum height Sz of outer surface 51 of cured resin layer 50. In addition to the method of incorporating particles into the curable resin composition as described above, examples include a method of processing outer surface 51 of the cured resin layer before or after curing by mold transfer.

[0056] The maximum height Sz of the outer surface 51 can be measured in accordance with ISO 25178 using a shape analysis laser microscope (product name "VK-X1000", manufactured by Keyence Corporation).

[0057] <Method of manufacturing reflective film> As an example of a method for manufacturing a reflective film 100, a method for manufacturing a reflective film 100 according to one embodiment of the present invention will be described below, in which a base film 10, a metal reflective layer 20, a blackening layer 30, a metal oxide layer 40, and a cured resin layer 50 are provided in this order from one side to the other in the thickness direction of the reflective film 100, as shown in Fig. 1. In the following description, one side will be referred to as the lower side, and the other side will be referred to as the upper side.

[0058] The reflective film 100 is manufactured by a roll-to-roll method, for example, as follows.

[0059] First, as shown in FIG. 2A, a metal reflective layer 20 is formed on a substrate film 10 (metal reflective layer forming step). Specifically, a metal film is formed on the first surface 11 of the substrate film 10 by a dry coating method to form the metal reflective layer 20. Examples of dry coating methods include sputtering and vapor deposition. The dry coating method is preferably sputtering.

[0060] The sputtering method uses, for example, a sputtering deposition apparatus capable of performing a film formation process using a roll-to-roll method. Specifically, in the sputtering method, a sputtering gas (inert gas) is introduced into a deposition chamber of the sputtering deposition apparatus under vacuum conditions, while a negative voltage is applied to a target placed on a cathode in the deposition chamber. This generates a glow discharge, ionizing the gas atoms, causing the gas ions to collide with the target surface at high speed, ejecting target material from the target surface, and the ejected target material is deposited on the substrate film 10.

[0061] The material of the target placed on the cathode in the film formation chamber (i.e., the material of the metal reflective layer 20) is the metal described above for the metal reflective layer 20. The air pressure in the film formation chamber during film formation by sputtering (sputter film formation) is, for example, 0.02 Pa or more and, for example, 1 Pa or less. Examples of power sources for applying voltage to the target include DC power sources, AC power sources, MF power sources, and RF power sources (the same applies to the sputter film formation for the blackening layer 30 and the metal oxide layer 40 described below). The absolute value of the discharge voltage during sputter film formation is, for example, 50 V or more and, for example, 500 V or less (the same applies to the sputter film formation for the blackening layer 30 and the metal oxide layer 40 described below).

[0062] Next, as shown in FIG. 2B, a blackening layer 30 is formed on the metal reflective layer 20 (blackening layer forming step). Specifically, a material is deposited on the metal reflective layer 20 by a dry coating method to form the blackening layer 30. Examples of dry coating methods include sputtering and vapor deposition. The dry coating method is preferably sputtering.

[0063] The material of the target placed on the cathode in the sputtering method (i.e., the material of the blackening layer 30) is, for example, a sintered body containing the metal compound and elemental metal described above with respect to the blackening layer 30. The atmospheric pressure in the deposition chamber during sputter deposition of the blackening layer 30 is, for example, 0.02 Pa or more and, for example, 1 Pa or less.

[0064] The dry coating method allows the blackening layer 30 to be formed thinner than conventional black ink layers formed with a resin component. In such a thin blackening layer 30, the difference in compressive residual stress between the side fixed to the metal reflective layer 20 and the side opposite the metal reflective layer 20 is small (the thinner the blackening layer 30, the smaller the difference in compressive residual stress on both sides). The small difference in compressive residual stress between one side and the other side in the thickness direction of the reflective film 100 in the blackening layer 30 helps ensure adhesion of the blackening layer 30 to the metal reflective layer 20.

[0065] Next, as shown in FIG. 2C, a metal oxide layer 40 is formed on the blackened layer 30 (metal oxide layer forming step). Specifically, a material is deposited on the blackened layer 30 by a dry coating method to form the metal oxide layer 40. Examples of dry coating methods include sputtering and vapor deposition. The dry coating method is preferably sputtering.

[0066] The material of the target placed on the cathode in the sputtering method (i.e., the material of the metal oxide layer 40) is, for example, the sintered body of metal oxide described above with respect to the metal oxide layer 40. The air pressure in the deposition chamber during sputter deposition of the metal oxide layer 40 is, for example, 0.02 Pa or more and, for example, 1 Pa or less.

[0067] The entire process from the metal reflective layer formation process to the metal oxide layer formation process is carried out on a single pass line while the workpiece film is transported roll-to-roll. During the process on a single pass line, the workpiece film is never exposed to the atmosphere. Sequentially forming the blackening layer 30 and metal oxide layer 40 on the metal reflective layer 20 without exposing the workpiece film to the atmosphere after the formation of the metal reflective layer 20 helps ensure adhesion of the blackening layer 30 and metal oxide layer 40 to the metal reflective layer 20.

[0068] Next, as shown in FIG. 2D, a cured resin layer 50 is formed on the metal oxide layer 40 (cured resin layer forming step). The cured resin layer 50 can be formed by applying a curable resin composition to the metal oxide layer 40 to form a coating film, and then curing the coating film. When the curable resin composition contains an ultraviolet-curable resin, the coating film is cured by ultraviolet irradiation. When the curable resin composition contains a thermosetting resin, the coating film is cured by heating.

[0069] In this manner, the reflective film 100 can be manufactured.

[0070] The reflective film 100 may not include the blackening layer 30, as shown in Fig. 3. Such a reflective film 100 can be produced by not performing the blackening layer forming step (Fig. 2B). In order to ensure the light-blocking properties of the reflective film 100, the reflective film 100 preferably includes the blackening layer 30.

[0071] The reflective film 100 may not include the metal oxide layer 40, as shown in Fig. 4. Such a reflective film 100 can be produced by not performing the metal oxide layer forming step (Fig. 2C). From the viewpoint of inhibiting corrosion of the metal reflective layer 20 and the blackening layer 30 by the metal oxide layer 40, the reflective film 100 preferably includes the metal oxide layer 40.

[0072] The reflective film 100 may not include the blackening layer 30 and the metal oxide layer 40. Such a reflective film 100 can be produced by not performing the blackening layer forming step ( FIG. 2B ) and the metal oxide layer forming step ( FIG. 2C ). From the viewpoint of ensuring light-blocking properties and inhibiting corrosion of the metal reflective layer 20 and the blackening layer 30 by the metal oxide layer 40, the reflective film 100 preferably includes the blackening layer 30 and the metal oxide layer 40.

[0073] As described above, the reflective film 100 has an arithmetic mean height Sa of 0.17 μm or more and 0.30 μm or less of the outer surface 51 of the cured resin layer 50. This allows the outer surface 51 of the cured resin layer 50 of the reflective film to have both good adhesion to the adhesive and resistance to damage.

[0074] Therefore, the reflective film 100 can achieve both adhesion to the adhesive and resistance to damage in the cured resin layer 50 as the outermost layer. However, damage to the outer surface 51 of the cured resin layer 50 may affect the optical properties and corrosion resistance of the reflective film. [Example]

[0075] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these examples. Furthermore, the specific numerical values of the blending amounts (contents), physical property values, parameters, etc. described below can be substituted with the upper limit (a numerical value defined as "not more than" or "less than") or lower limit (a numerical value defined as "not less than" or "greater than") of the corresponding blending amounts (contents), physical property values, parameters, etc. described in the "Description of Embodiments."

[0076] <Production of reflective film> Example 1 First, a white polyethylene terephthalate (PET) film (product name "Lumirror E20", thickness 38 μm, manufactured by Toray) was prepared as a substrate film.

[0077] Next, a metal reflective layer, a blackening layer, and a metal oxide layer were formed in that order on one side (first side) of the PET film by sputtering (sputter deposition process). In this sputter deposition process, a roll-to-roll sputter deposition apparatus (DC magnetron sputter deposition apparatus) was used. The apparatus was equipped with a payout chamber, a first deposition chamber, a second deposition chamber, a third deposition chamber, and a winding chamber. The payout chamber was equipped with a payout roller. The winding chamber was equipped with a winding roller. In the first to third deposition chambers, the deposition process was carried out while the work film was running from the payout chamber to the winding chamber using a roll-to-roll method.

[0078] Specifically, in the sputtering process, a roll of base film was set on a feed roller, and the first sputtering deposition in the first deposition chamber, the second sputtering deposition in the second deposition chamber, and the third sputtering deposition in the third deposition chamber were carried out sequentially. The work film (base film / metal reflective layer / blackened layer / metal oxide layer) was then wound onto a take-up roller. In the first sputtering deposition, a 75 nm thick metal reflective layer (Al) was formed on the first side of the PET film. In the subsequent second sputtering deposition, a 25 nm thick blackened layer (In2O3 + Cu) was formed on the metal reflective layer. In the subsequent third sputtering deposition, a 20 nm thick metal oxide layer (ITO) was formed on the blackened layer. The specific conditions for each sputtering deposition were as follows:

[0079] In the first sputtering deposition, the sputtering deposition apparatus (feed chamber, first to third deposition chambers, and take-up chamber) was evacuated, and then argon (Ar) was introduced as a sputtering gas into the first deposition chamber, and the pressure inside the first deposition chamber was set to 0.3 to 0.4 Pa. An Al target (Mitsui Metals) was used as the target. A DC power supply was used as the power source for applying voltage to the target. The deposition temperature (the temperature of the substrate film on which the Al layer is laminated) was set to 40°C. The type of sputtering gas, the pressure inside the deposition chamber, the type of power source, and the deposition temperature were the same for the second and third sputtering depositions.

[0080] In the second sputtering film formation, a black inorganic target (product name "DIABLA12", a mixed target of indium oxide (In2O3) and copper (Cu), In proportion 67.3 (±3) mass %, manufactured by Mitsubishi Materials Corporation) was used as the target.

[0081] In the third sputtering film formation, an ITO target (a composite oxide of indium oxide and tin oxide, tin oxide concentration 10% by mass, manufactured by Mitsui Metals) was used as the target.

[0082] Next, a curable resin composition was applied onto the metal oxide layer using a gravure roll to form a coating. The curable resin composition contained 100 parts by mass of an ultraviolet-curable acrylic urethane resin (product name "AICA ITRON Z-844", manufactured by AICA Kogyo Co., Ltd.), 1.0 part by mass of antiblocking (AB) particles (product name "SSX103", crosslinked polymethacrylate particles, average particle size (D50) 3.0 μm, manufactured by Sekisui Plastics Co., Ltd.), and methyl ethyl ketone as a solvent. Table 1 shows the composition of the curable resin composition excluding the solvent methyl ethyl ketone. Next, the coating was dried and then cured by ultraviolet irradiation to form a cured resin layer with a thickness of 1 μm.

[0083] In this manner, the reflective film of Example 1 was produced. As shown in Table 2, the reflective film of Example 1 includes a substrate film (white PET, thickness 38 μm), a metal reflective layer (Al, thickness 75 nm), a blackening layer (In2O3+Cu, thickness 25 nm), a metal oxide layer (ITO, thickness 20 nm), and a cured resin layer (thickness 1 μm). Note that the thickness of the cured resin layer is shown in Table 2 excluding the thickness of the AB particles. The thicknesses of the metal reflective layer, blackening layer, and metal oxide layer were measured using a field emission transmission electron microscope, as described below, after the reflective film was produced.

[0084] [Table 1]

[0085] [Table 2]

[0086] [Examples 2 and 3] The reflective films of Examples 2 and 3 were produced in the same manner as the reflective film of Example 1, except that the average particle size (D50) of the AB particles contained in the curable resin composition was changed as shown in Table 1.

[0087] Comparative Examples 1 to 3 Each of the reflective films of Comparative Examples 1 to 3 was produced in the same manner as the reflective film of Example 1, except that the average particle size (D50) and number of parts of the AB particles contained in the curable resin composition were changed as shown in Table 1.

[0088] <Measurement and evaluation> [Thickness measurement using a field emission transmission electron microscope (FE-TEM)] The thicknesses of the metal reflective layer, blackened layer, and metal oxide layer in each reflective film of the Examples and Comparative Examples were measured using a field emission transmission electron microscope (FE-TEM). Specifically, first, a cross-sectional observation sample of each multilayer film of the Examples and Comparative Examples was prepared using an FIB microsampling method. In the FIB microsampling method, an FIB device (product name "FB2200", manufactured by Hitachi) was used, and an acceleration voltage was set to 10 kV. Next, the cross-section of the multilayer film in the cross-sectional observation sample was observed using an FE-TEM, and the thicknesses of the metal reflective layer, blackened layer, and metal oxide layer were measured in the observed image. In the observation, an FE-TEM device (product name "JEM-2800", manufactured by JEOL) was used, and an acceleration voltage was set to 200 kV. The measurement results are shown in Table 2.

[0089] [Arithmetic mean height Sa, maximum height Sz] The arithmetic mean height Sa and maximum height Sz (ISO 25178) of the outer surface of the cured resin layer in each reflective film of the Examples and Comparative Examples were determined from stereoscopic images taken with a shape analysis laser microscope (product name "VK-X1000", manufactured by Keyence Corporation). The measurement results are shown in Table 3.

[0090] [Water contact angle] The water contact angle (pure water contact angle) was measured for the outer surface of the cured resin layer in each reflective film of the Examples and Comparative Examples. Specifically, a water droplet was first formed on the outer surface of the cured resin layer of the reflective film by dropping 3.5 μL of distilled water. Next, the angle formed between the surface of the water droplet on the cured resin layer and the surface (outer surface) of the cured resin layer was measured. A contact angle measuring device (product name "FACE CA-X type", manufactured by Kyowa Interface Science Co., Ltd.) was used for the measurement. The measurement conditions were a temperature of 23°C and a relative humidity of 50%. The measurement results are shown in Table 3.

[0091] [Adhesion] For each of the reflective films of the Examples and Comparative Examples, the adhesion of the outer surface of the cured resin layer to the adhesive was examined as follows.

[0092] First, a sample film (100 mm long x 25 mm wide) was cut from the reflective film. Next, the outer surface of the cured resin layer of the sample film was attached to a glass plate using double-sided tape (product name "No. 5000" manufactured by Nitto Denko). Next, a 180° peel test was conducted to peel the sample film from the double-sided adhesive tape on the glass plate in the longitudinal direction, and the force required for peeling (peel force) was measured. This measurement was performed using a tensile tester (product name "TCM-1kNB" manufactured by NMB-Minebea Co., Ltd.). The measurement temperature was 23°C, the relative humidity was 50%, the sample film was peeled from the glass plate at a 180° peel angle, and the pulling speed was 300 mm / min. The measured peel force is shown in Table 3 as adhesive strength (N / 25 mm) of the adhesive (PSA).

[0093] [Injury Assessment] The resistance of the cured resin layer to scratches was examined for each of the reflective films of the Examples and Comparative Examples as follows.

[0094] First, the tip of a rechargeable touch pen for touch panels (product name "MS-TP22WH", manufactured by MS Solutions) was slid across the outer surface (exposed surface) of the cured resin layer of the reflective film. The sliding load was 300 g, the sliding distance was 100 mm, the sliding speed was 150 mm / sec, and the number of strokes was 1. Next, light was irradiated onto the slid area on the cured resin layer side of the reflective film. An LED light source (product name "MG-845R", manufactured by GENTOS) was used as the light source for light irradiation. Next, the anti-reflection film was visually observed from the base film side to confirm whether or not the irradiated light had passed through the reflective film. When no penetration of the irradiated light was observed, the film was evaluated as "no scratches," and when penetration of the irradiated light was observed, the film was evaluated as "scratches." The evaluation results are shown in Table 3.

[0095] [Table 3] [Explanation of symbols]

[0096] 10 Base film 11 Page 1 12 Side 2 20 Metal reflective layer 30 Blackened layer 40 Metal Oxide Layer 50 Cured resin layer 51 External surface 100 Reflective Film

Claims

1. A reflective film comprising a substrate film, a metal reflective layer, and a cured resin layer in this order in a thickness direction, A reflective film, wherein the arithmetic mean height Sa of the outer surface of the cured resin layer on the side opposite to the metal reflective layer is 0.17 μm or more and 0.30 μm or less.

2. The reflective film according to claim 1 , wherein the cured resin layer has an outer surface opposite to the metal reflective layer, and the outer surface has a maximum height Sz of 5.0 μm or less.

3. The reflective film of claim 1 , wherein the metallic reflective layer is an aluminum layer.

4. The reflective film according to claim 1 , further comprising a metal oxide layer between the metal reflective layer and the cured resin layer.

5. The reflective film of claim 4 , wherein the metal oxide layer is an indium tin oxide layer.

Images