Reflective film

Abstract

The invention relates to a reflective film. This reflective film (100) is provided with a base film (10), a metal reflective layer (20), and a cured resin layer (50) in this order in the thickness direction of the reflective film. The arithmetic mean height (Sa) of the outer surface (51) of the cured resin layer (50) on the opposite side from the metal reflective layer (20) is 0.17 [mu] m or more and 0.30 [mu] m or less.

Description

Technical Field

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

[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 them. The housing has a frame portion that serves as a frame around the image display surface. A reflective film is disposed on the inner wall surface within the frame portion.

[0003] The reflective film sequentially includes a base film, a metal reflective layer, and a cured resin layer as an outer coating (OC) in the thickness direction. The OC side of the reflective film is joined to the inner wall surface via an adhesive, whereby the reflective film is assembled within the frame portion. The reflective film reflects light from the backlight toward the liquid crystal panel using the metal reflective layer within the frame portion. Thus, the light from the backlight is effectively utilized. As such a reflective film, a reflective / light-shielding adhesive tape that sequentially includes a white resin film, a metal thin film layer, and a coating in the thickness direction is known (for example, refer to Patent Document 1 below).

[0004] As described above, since the reflective film is joined to the inner wall surface using an adhesive, adhesiveness with the adhesive is required. However, an OC with too high adhesiveness lacks slidability. An OC lacking slidability is easily damaged when contacting peripheral members.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-184443 Summary of the Invention

[0008] The present invention provides a reflective film capable of achieving both adhesiveness with an adhesive and damage resistance on the outer surface of the cured resin layer in the reflective film.

[0009] The present invention [1] is a reflective film that sequentially includes a base film, a metal reflective layer, and a cured resin layer in the thickness direction, and 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.

[0010] The present invention [2] is the reflective film as described in [1] above, 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.

[0011] The present invention [3] is the reflective film as described in [1] above, wherein the metal reflective layer is an aluminum layer.

[0012] The reflective film of the present invention [4] is the reflective film according to any one of [1] to [3] above, wherein a metal oxide layer is further provided between the metal reflective layer and the cured resin layer.

[0013] The reflective film of the present invention [5] is the reflective film according to [4] above, wherein the metal oxide layer is an indium tin oxide layer.

[0014] Advantages of the Invention

[0015] The reflective film of the present invention sequentially includes a base film, a metal reflective layer, and a cured resin layer in the thickness direction, and the arithmetic mean height Sa of the outer surface on the side opposite to the metal reflective layer of the cured resin 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 balance the adhesiveness to the adhesive and the resistance to damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic cross-sectional view of an embodiment of the reflective film of the present invention.

[0017] Figures 2A to 2D denotes Figure 1 the manufacturing method of the reflective film shown. Figure 2A denotes the step of forming a metal reflective layer on the base film, Figure 2B denotes the step of forming a blackening layer on the metal reflective layer, Figure 2C denotes the step of forming a metal oxide layer on the blackening layer, Figure 2D denotes the step of forming a cured resin layer on the metal oxide layer.

[0018] Figure 3 is a schematic cross-sectional view of a modified example of the reflective film of the present invention. This modified example does not have a blackening layer.

[0019] Figure 4 is a schematic cross-sectional view of another modified example of the reflective film of the present invention. This modified example does not have a metal oxide layer.

[0020] REFERENCE SIGNS LIST

[0021] 10: Base film; 11: First surface; 12: Second surface; 20: Metal reflective layer; 30: Blackening layer; 40: Metal oxide layer; 50: Cured resin layer; 51: Outer surface; 100: Reflective film. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] <Reflective Film>

[0023] As Figure 1As shown in the figure, the reflective film 100 of an embodiment of the present invention sequentially includes a base film 10, a metal reflective layer 20, a blackening layer 30, a metal oxide layer 40, and a cured resin layer 50 from one side to the other side in the thickness direction of the reflective film 100. The reflective film 100 extends in a direction (plane direction) orthogonal to the thickness direction. The reflective film 100 is, for example, a reflective film that prevents light from the backlight of a liquid crystal display device from leaking out of the housing. It should be noted that in the following description, one side is referred to as the lower side and the other side is referred to as the upper side.

[0024] 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, the thickness of the reflective film 100 is preferably 20 μm or more, more preferably 30 μm or more, and further preferably 35 μm or more. In addition, from the viewpoint of operability, the thickness of the reflective film 100 is preferably 300 μm or less, more preferably 200 μm or less, and further preferably 150 μm or less.

[0025] [Base film]

[0026] The base film 10 is a base material that ensures the strength of the reflective film 100. As Figure 1 shown, the base film 10 has a first surface 11 that is the surface on the other side in the thickness direction of the reflective film 100, and a second surface 12 that is the surface on one side in the thickness direction of the reflective film 100. In addition, the base film 10 is, for example, a flexible transparent resin film. Examples of the material of 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 the polyester resin include: polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Examples of the polyolefin resin include: polyethylene, polypropylene, and cycloolefin polymer.

[0027] Examples of the acrylic resin include: polymethacrylate. From the viewpoints of transparency and strength, the material of the base film 10 is preferably a polyester resin, and more preferably PET.

[0028] From the viewpoint of ensuring the light reflectivity of the base film 10, the base film 10 is preferably a white film. The white film is obtained, for example, in the form of a resin film containing particles such as inorganic fillers that generate light scattering. Examples of such particles include titanium oxide, calcium carbonate, barium sulfate, silica, and talc, and at least one selected from the group consisting of titanium oxide and silica is preferably used. These particles can 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 further, for example, 2 μm or less, preferably 1 μm or less. The content ratio of the particles in the base film 10 as the white film is, for example, 5% by mass or more, preferably 10% by mass or more, and further, for example, 50% by mass or less, preferably 40% by mass or less.

[0029] From the viewpoints of suppressing the intrusion of water vapor from the base film 10 side of the reflective film 100 into the metal reflective layer 20 and the blackening layer 30 (suppressing vapor intrusion) and the strength of the reflective film 100, the thickness of the base film 10 is preferably 20 μm or more, more preferably 30 μm or more, and further preferably 35 μm or more. From the viewpoint of ensuring the operability of the base film 10 in the roll-to-roll method, the thickness of the base film 10 is preferably 300 μm or less, more preferably 200 μm or less, and further preferably 150 μm or less. From the viewpoint of taking into account the above-mentioned suppression of vapor intrusion and strength and the above-mentioned operability, the thickness of the base film 10 is preferably 20 to 300 μm, more preferably 30 to 200 μm, and further preferably 35 to 150 μm.

[0030] From the viewpoint of ensuring the adhesion between the metal reflective layer 20 and the base film 10, the first surface 11 of the base film 10 can be surface-modified. Examples of the surface modification treatment include corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

[0031] [Metal reflective layer]

[0032] 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 the present embodiment, as Figure 1 shown, the metal reflective layer 20 is disposed on the first surface 11 of the base film 10. That is, in the present embodiment, the metal reflective layer 20 is in contact with the first surface 11.

[0033] The metal reflective layer 20 is formed of a metal having light reflectivity. Examples of the metal for forming 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.

[0034] 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 30 nm or more, more preferably 50 nm or more, further preferably 60 nm or more, and even more preferably 70 nm or more. From the viewpoint of ensuring the adhesion of the metal reflective layer 20 to the base film 10, the thickness of the metal reflective layer 20 is preferably 500 nm or less, more preferably 250 nm or less, further preferably 150 nm or less, and even more preferably 120 nm or less. From the viewpoint of balancing the above light reflectivity and the above adhesion, the thickness of the metal reflective layer 20 is preferably 30 to 500 nm, more preferably 50 to 250 nm, further preferably 60 to 150 nm, and even more preferably 70 to 120 nm.

[0035] [Blackening layer]

[0036] 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 the present embodiment, as shown in Figure 1 shown, the blackening layer 30 is disposed on the metal reflective layer 20. That is, in the present embodiment, the blackening layer 30 is in contact with the metal reflective layer 20.

[0037] The blackening layer 30 is a layer with high light absorption. In the present embodiment, it is an inorganic blackening layer containing a metal compound and elemental metal. The blackening layer 30 may contain a plurality of metal compounds. The blackening layer 30 may contain a plurality of elemental metals.

[0038] The metal compound is a compound of a metal and a non-metal. Examples of the metal compound 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.

[0039] As the elemental metal (second metal), examples 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 a plurality of elemental metals, the plurality of elemental metals preferably contain a metal different from the first metal. More preferably, the elemental metal is a metal other than the first metal.

[0040] From the viewpoint of achieving high light-shielding properties in the blackening layer 30, the proportion of the first metal in the blackening layer 30 is preferably 10 atomic% or more, more preferably 20 atomic% or more, and further preferably 90 atomic% or less, more preferably 80 atomic% or less. 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%. From the viewpoint of achieving high light-shielding properties in the blackening layer 30, the proportion of the second metal in the blackening layer 30 is preferably 10 atomic% or more, more preferably 20 atomic% or more, and further preferably 90 atomic% or less, more preferably 80 atomic% or less. 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%.

[0041] From the viewpoint of achieving high light-shielding properties in the blackening layer 30, the blackening layer 30 preferably contains a metal oxide as the metal compound and contains an elemental metal other than the first metal, and more preferably contains indium oxide as the metal compound and contains copper as the elemental metal. When the blackening layer 30 contains indium oxide and copper, from the viewpoint of achieving high light-shielding properties in the blackening layer 30, the proportion of In in the blackening layer 30 is preferably 40 atomic% or more, more preferably 50 atomic% or more, and further preferably 90 atomic% or less, more preferably 80 atomic% or less. 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, from the viewpoint of achieving high light-shielding properties in the blackening layer 30, the proportion of Cu in the blackening layer 30 is preferably 5 atomic% or more, more preferably 10 atomic% or more, and further preferably 50 atomic% or less, more preferably 40 atomic% or less. That is, the proportion of Cu in the blackening layer 30 is preferably 5 to 50 atomic%, more preferably 10 to 40 atomic%.

[0042] From the viewpoint of ensuring the light-shielding property of the blackening layer 30 and the reflective film 100, the thickness of the blackening layer 30 is preferably 5 nm or more, more preferably 10 nm or more, further preferably 20 nm or more, and still more preferably 25 nm or more. From the viewpoint of ensuring the adhesion of the blackening layer 30 to the substrate (the metal reflective layer 20 in this embodiment), the thickness of the blackening layer 30 is preferably 400 nm or less, more preferably 200 nm or less, further preferably 100 nm or less, and still more preferably 50 nm or less. From the viewpoint of taking into account both the above light-shielding property and the above adhesion, the thickness of the blackening layer 30 is preferably 5 to 400 nm, more preferably 10 to 200 nm, further preferably 20 to 100 nm, and still more preferably 25 to 50 nm.

[0043] From the viewpoint of ensuring the light-shielding property of the blackening layer 30 and the reflective film 100, the luminous transmittance (Y value) of the blackening layer 30 for light with wavelengths from 380 nm to 780 nm in the CIE-XYZ color system is preferably 0.1% or less, more preferably 0.05% or less, and further preferably 0.03% or less. 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).

[0044] [Metal oxide layer]

[0045] 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 Figure 1 shown, 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, and 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.

[0046] In this embodiment, the metal oxide layer 40 is a barrier layer. The metal oxide layer 40, for example, inhibits the intrusion of water vapor from the cured resin layer 50 side into the blackening layer 30 and the metal reflective layer 20.

[0047] Inhibiting the intrusion of water vapor helps to inhibit corrosion such as galvanic corrosion of the metal reflective layer 20 and the blackening layer 30.

[0048] Examples of the metal of the metal oxide forming 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 property of the metal oxide layer 40, preferably, the metal of the metal oxide is at least one selected from the group consisting of In, Zn, Sn, Mg, Ni, Co, and Cr. More preferably, the metal oxide layer 40 is an indium tin oxide (ITO) layer.

[0049] From the viewpoint of ensuring the water vapor barrier property of the metal oxide layer 40, the thickness of the metal oxide layer 40 is preferably 5 nm or more, more preferably 8 nm or more, and further preferably 10 nm or more. From the viewpoint of ensuring the adhesion between the metal oxide layer 40 and the blackened layer 30, the thickness of the metal oxide layer 40 is preferably 200 nm or less, more preferably 150 nm or less, and further preferably 100 nm or less. From the viewpoint of balancing the above water vapor barrier property and the above adhesion, the thickness of the metal oxide layer 40 is preferably 5 to 200 nm, more preferably 8 to 150 nm, and further preferably 10 to 100 nm.

[0050] [Cured resin layer]

[0051] 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 the present embodiment, as Figure 1 shown, the cured resin layer 50 is disposed on the metal oxide layer 40. That is, in the present embodiment, the cured resin layer 50 is in contact with the metal oxide layer 40. The cured resin layer 50 is an outer coating 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 coating for making the reflective film 100 less likely to form scratches.

[0052] 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 can be used alone or in combination of two or more.

[0053] From the viewpoint of ensuring the 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.

[0054] In addition, examples of the curable resin include ultraviolet curable resins and thermosetting resins. Since curing can be achieved without high-temperature heating, it helps to improve the manufacturing efficiency of the reflective film 100. From this perspective, the curable resin is preferably an ultraviolet curable resin.

[0055] From the perspective of ensuring the hardness of the cured resin layer 50, the proportion of the curable resin in the cured resin layer 50 (wherein, the proportion in the cured resin layer 50 excluding the particles described later. The same applies hereinafter) is preferably 95.0% by mass or more, more preferably 97.0% by mass or more, and further preferably 99.0% by mass or more. From the perspective of ensuring the proportion of other components in the cured resin layer 50, the proportion of the curable resin in the cured resin layer 50 is preferably 99.9% by mass or less, more preferably 99.7% by mass or less, and further preferably 99.5% by mass or less. From the perspective of balancing the above-mentioned hardness ensuring and the ensuring of the proportion of other components, the said proportion of the curable resin is preferably 95.0 to 99.9% by mass, more preferably 97.0 to 99.7% by mass, and further preferably 99.0 to 99.5% by mass.

[0056] The cured resin layer 50 preferably contains particles. That is, the curable resin composition preferably contains particles. By adjusting the content of the particles contained in the cured resin layer 50 and / or the average particle diameter (D50) of the particles, the arithmetic mean height Sa of the outer surface 51 of the cured resin layer 50 can be adjusted. Moreover, by adjusting the arithmetic mean height Sa of the outer surface 51 of the cured resin layer 50, the slidability of the outer surface 51 with respect to the surrounding members and the adhesion to the adhesive can be adjusted.

[0057] In addition, by adjusting the content of the particles contained in the cured resin layer 50 and / or the average particle diameter (D50) of the particles, the maximum height Sz of the outer surface 51 of the cured resin layer 50 can be adjusted. Moreover, by adjusting the maximum height Sz of the outer surface 51 of the cured resin layer 50, the adhesion of the outer surface 51 of the cured resin layer 50 to the adhesive can be adjusted.

[0058] Examples of the particles include inorganic oxide particles and organic particles. Examples of the material of the inorganic oxide particles include: silica, alumina, titanium dioxide, zirconium oxide, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide. Examples of the material of the organic particles include: polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, and polycarbonate. The particles can be used alone or in combination of two or more. As the particles, organic particles are preferably used. As the organic particles, polymethacrylate particles are preferably used. As the particles, inorganic oxide particles can be used.

[0059] As the inorganic oxide particles, at least one selected from silica particles and zirconia particles is preferably used.

[0060] 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, further preferably 2.0 μm or more, and still more preferably 2.5 μm or more. The average particle diameter (D50) of the particles is preferably 6.0 μm or less, more preferably 5.0 μm or less, further preferably 4.0 μm or less, and still more preferably 3.5 μm or less. By adjusting the average particle diameter (D50) of the particles to the above range, the arithmetic mean height Sa and / or the maximum height Sz of the outer surface 51 of the cured resin layer 50 can be adjusted to an appropriate range.

[0061] The average particle diameter (D50) of the particles is the median particle diameter in the volume-based particle size distribution (the particle diameter at which the volume cumulative frequency reaches 50% starting from the small-diameter side), and is obtained, for example, based on the particle size distribution obtained by the laser diffraction-scattering method.

[0062] The content of the particles in the cured resin layer 50 is, for example, 0.1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the curable resin. The content of the particles in the cured resin layer 50 is preferably 0.3 part by mass or more, more preferably 0.6 part by mass or more, further preferably 0.8 part by mass or more, and still more preferably 0.9 part by mass or more with respect to 100 parts by mass of the curable resin. The content of the particles in the cured resin layer 50 is preferably 5.0 parts by mass or less, more preferably 3.0 parts by mass or less, further preferably 1.5 parts by mass or less, and still more preferably 1.2 parts by mass or less with respect to 100 parts by mass of the curable resin. By adjusting the average particle diameter (D50) of the particles to the above range, the arithmetic mean height Sa and / or the maximum height Sz of the outer surface 51 of the cured resin layer 50 can be adjusted to an appropriate range.

[0063] 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 silicone-based leveling agents, fluorine-based leveling agents, and acrylic-based leveling agents.

[0064] From the viewpoint of exhibiting sufficient scratch resistance in the cured resin layer 50, the thickness of the cured resin layer 50 is preferably 0.1 μm or more, more preferably 0.5 μm or more, further preferably 0.7 μm or more, and still more preferably 0.9 μm or more. From the viewpoint of ensuring the adhesion between the cured resin layer 50 and the metal oxide layer 40, the thickness of the cured resin layer 50 is preferably 5 μm or less, more preferably 3 μm or less, further preferably 2 μm or less, and still more preferably 1.5 μm or less. From the viewpoint of taking into account both the above-mentioned scratch resistance and the above-mentioned adhesion, the thickness of the cured resin layer 50 is preferably 0.1 to 5 μm, more preferably 0.5 to 3 μm, further preferably 0.7 to 2 μm, and still more preferably 0.9 to 1.5 μm. It should be noted that the thickness of the cured resin layer 50 is the average value of the thickness of only the cured resin layer 50, ignoring the unevenness caused by particles and the like.

[0065] 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 retaining the particles in the cured resin layer 50, this ratio is preferably 15 or less, more preferably 10 or less, and further preferably 5 or less.

[0066] From the viewpoint of the effect of adjusting the arithmetic mean height Sa of the cured resin layer 50, this ratio is preferably 1 or more, more preferably 2 or more, and further preferably 2.5 or more.

[0067] The cured resin layer 50 has an outer surface 51 on the side opposite to the metal reflection layer 40. The outer surface 51 is the surface of the reflective film 100 that is exposed on the other side. The arithmetic mean height Sa of the outer surface 51 is, for example, 0.17 μm or more and 0.30 μm or less.

[0068] 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 further preferably 0.20 μm or more. By making the arithmetic mean height Sa of the outer surface the above lower limit or more, the contact area between the outer surface 51 and the surrounding members is reduced, ensuring the slidability of the outer surface 51 with respect to the surrounding members. As a result, the non-damageability of the outer surface 51 is ensured. It should be noted that here, the surrounding members are members that may come into contact during assembly, and examples include the frame portion of a liquid crystal display device, etc.

[0069] In addition, 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 further preferably 0.24 μm or less. By making the arithmetic mean height Sa of the outer surface 51 the above upper limit or less, the adhesion between the outer surface 51 and the adhesive is ensured.

[0070] In addition, when the cured resin layer 50 contains particles as described above, if the arithmetic mean roughness Sa is too high, particle detachment may occur. The detached particles are present between the outer surface 51 of the cured resin layer 50 and the surrounding members, thus damaging the cured resin layer 50. From the viewpoint of suppressing particle detachment, the arithmetic mean height Sa of the outer surface 51 is preferably 0.40 μm or less, more preferably 0.35 μm or less, further preferably 0.3 μm or less, and still more preferably 0.25 μm or less.

[0071] The method for adjusting the arithmetic mean height Sa of the outer surface 51 of the cured resin layer 50 is not particularly limited. In addition to the method of containing particles in the cured resin composition as described above, methods such as processing the outer surface 51 of the cured resin layer before or after curing by die transfer can be cited.

[0072] The arithmetic mean height Sa of the above-mentioned outer surface 51 can be measured using a shape analysis laser microscope (product name "VK-X1000", manufactured by KEYENCE Corporation) in accordance with ISO 25178.

[0073] 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 further preferably 4.0 μm or less. By making the maximum height Sz of the outer surface 51 below the above upper limit, the adhesion between the outer surface 51 and the adhesive can be ensured. It should be noted that 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, for example, 1.0 μm or more.

[0074] The method for adjusting the maximum height Sz of the outer surface 51 of the cured resin layer 50 is not particularly limited. In addition to the method of containing particles in the cured resin composition as described above, methods such as processing the outer surface 51 of the cured resin layer before or after curing by die transfer can be cited.

[0075] The maximum height Sz of the above-mentioned outer surface 51 can be measured using a shape analysis laser microscope (product name "VK-X1000", manufactured by KEYENCE Corporation) in accordance with ISO 25178.

[0076] <Method for manufacturing a reflective film>

[0077] Hereinafter, as an example of the method for manufacturing the reflective film 100, Figure 1A method for manufacturing a reflective film 100 according to an embodiment of the present invention, which sequentially 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 from one side to the other side in the thickness direction of the reflective film 100. It should be noted that in the following description, one side is referred to as the lower side and the other side is referred to as the upper side.

[0078] The reflective film 100 can be manufactured, for example, in a roll-to-roll manner as follows.

[0079] First, as Figure 2A shown, a metal reflective layer 20 is formed on the 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. As the dry coating method, for example, a sputtering method and an evaporation method can be cited. The dry coating method is preferably a sputtering method.

[0080] In the sputtering method, for example, a sputtering film forming apparatus capable of performing a film forming process in a roll-to-roll manner is used. In the sputtering method, specifically, a sputtering gas (inert gas) is introduced into a film forming chamber provided in the sputtering film forming apparatus under a vacuum condition, and a negative voltage is applied to a target disposed on a cathode in the film forming chamber. Thereby, glow discharge is generated to ionize gas atoms, and the gas ions collide with the target surface at high speed, ejecting the target material from the target surface, and depositing the ejected target material on the substrate film 10.

[0081] The material of the target disposed on the cathode in the film forming chamber (i.e., the material of the metal reflective layer 20) is the metal mentioned above with respect to the metal reflective layer 20. The air pressure in the film forming chamber during film formation (sputtering film formation) based on the sputtering method is, for example, 0.02 Pa or more, and further, for example, 1 Pa or less. As a power source for applying a voltage to the target, for example, a DC power source, an AC power source, an MF power source, and an RF power source (the same applies to the sputtering film formation described later regarding the blackening layer 30 and the metal oxide layer 40) can be cited. The absolute value of the discharge voltage during sputtering film formation is, for example, 50 V or more, and further, for example, 500 V or less (the same applies to the sputtering film formation described later regarding the blackening layer 30 and the metal oxide layer 40).

[0082] Next, as Figure 2B shown, a blackening layer 30 is formed on the metal reflective layer 20 (blackening layer forming step). Specifically, a material is formed into a film on the metal reflective layer 20 by a dry coating method to form the blackening layer 30. As the dry coating method, for example, a sputtering method and an evaporation method can be cited. The dry coating method is preferably a sputtering method.

[0083] The material of the target disposed on the cathode in the sputtering method (i.e., the material of the blackening layer 30) is, for example, the sintered body containing a metal compound and elemental metal mentioned above with respect to the blackening layer 30. The air pressure in the film formation chamber during the sputter film formation of the blackening layer 30 is, for example, 0.02 Pa or more, and further, for example, 1 Pa or less.

[0084] According to the dry coating method, the blackening layer 30 can be formed thinner than the conventional black ink layer formed by containing a resin component. In such a thin blackening layer 30, the difference between the compressive residual stress fixed to one side of the metal reflection layer 20 and the compressive residual stress on the opposite side of the metal reflection layer 20 is small (the thinner the blackening layer 30, the smaller the difference in compressive residual stress on both sides). Moreover, the smaller 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 contributes to ensuring the adhesion between the blackening layer 30 and the metal reflection layer 20.

[0085] Next, as Figure 2C shown, a metal oxide layer 40 is formed on the blackening layer 30 (metal oxide layer formation process). Specifically, the metal oxide layer 40 is formed by film-forming a material on the blackening layer 30 by a dry coating method. Examples of the dry coating method include a sputtering method and an evaporation method. The dry coating method is preferably a sputtering method.

[0086] The material of the target disposed on the cathode in the sputtering method (i.e., the material of the metal oxide layer 40) is, for example, the sintered body of the metal oxide mentioned above with respect to the metal oxide layer 40. The air pressure in the film formation chamber during the sputter film formation of the metal oxide layer 40 is, for example, 0.02 Pa or more, and further, for example, 1 Pa or less.

[0087] A series of processes from the metal reflection layer formation process to the metal oxide layer formation process are carried out on one transfer line (the English is pass line) while conveying the work film (the English is work film) in a roll-to-roll manner. In the processes on one transfer line, the work film is never exposed to the atmosphere. After forming the metal reflection layer 20, forming the blackening layer 30 and the metal oxide layer 40 in sequence on the metal reflection layer 20 without exposing the work film to the atmosphere contributes to ensuring the adhesion between the blackening layer 30 and the metal oxide layer 40 and the metal reflection layer 20.

[0088] Next, as Figure 2DAs shown, 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 on 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.

[0089] As described above, the reflective film 100 can be manufactured.

[0090] As Figure 3 shown, the reflective film 100 may not have the blackening layer 30. Such a reflective film 100 can be manufactured by not performing the blackening layer forming step ( Figure 2B ). In order to ensure the light-shielding property of the reflective film 100, the reflective film 100 preferably has the blackening layer 30.

[0091] As Figure 4 shown, the reflective film 100 may not have the metal oxide layer 40. Such a reflective film 100 can be manufactured by not performing the metal oxide layer forming step ( Figure 2C ). From the viewpoint of suppressing the corrosion of the metal reflective layer 20 and the blackening layer 30 by the metal oxide layer 40, the reflective film 100 preferably has the metal oxide layer 40.

[0092] The reflective film 100 may not have the blackening layer 30 and the metal oxide layer 40. Such a reflective film 100 can be manufactured by not performing the blackening layer forming step ( Figure 2B ) and the metal oxide layer forming step ( Figure 2C ). From the viewpoints of ensuring the light-shielding property and suppressing the corrosion of the metal reflective layer 20 and the blackening layer 30 by the metal oxide layer 40, the reflective film 100 preferably has the blackening layer 30 and the metal oxide layer 40.

[0093] As described above, the arithmetic mean height Sa of the outer surface 51 of the cured resin layer 50 of the reflective film 100 is 0.17 μm or more and 0.30 μm or less. Thus, both the adhesiveness to the adhesive and the resistance to damage can be achieved on the outer surface 51 of the cured resin layer 50 of the reflective film.

[0094] Therefore, the reflective film 100 can achieve both the adhesiveness to the adhesive and the resistance to damage on the cured resin layer 50 as the outermost layer. It should be noted that the damage to the outer surface 51 of the cured resin layer 50 may affect the optical properties and corrosion resistance of the reflective film.

[0095] [Examples]

[0096] Examples are shown below to specifically illustrate the present invention. However, the present invention is not limited to the examples. In addition, the specific numerical values such as the compounding amounts (contents), physical property values, parameters, etc. described below can be replaced with the upper limits (values defined as "below" or "less than") or lower limits (values defined as "above" or "more than") of the corresponding compounding amounts (contents), physical property values, parameters, etc. described in the "Detailed Description".

[0097] <Fabrication of Reflective Film>

[0098] 〔Example 1〕

[0099] First, a white polyethylene terephthalate (PET) film (product name "Lumirror E20", thickness 38 μm, manufactured by TORAY) is prepared as the base film.

[0100] Next, a metal reflective layer, a blackening layer, and a metal oxide layer are sequentially formed on one surface (the first surface) of the PET film by sputtering (sputtering film formation process). In this sputtering film formation process, a roll-to-roll sputtering film formation apparatus (DC magnetron sputtering film formation apparatus) is used. The apparatus includes an evacuation chamber, a first film formation chamber, a second film formation chamber, a third film formation chamber, and a winding chamber. The evacuation chamber includes an evacuation roll. The winding chamber includes a winding roll. In the first to third film formation chambers, the working film travels from the evacuation chamber to the winding chamber in a roll-to-roll manner, and the film formation process is performed.

[0101] In the sputtering film formation process, specifically, a roll of the base film is set on the evacuation roll, and the first sputtering film formation in the first film formation chamber, the second sputtering film formation in the second film formation chamber, and the third sputtering film formation in the third film formation chamber are sequentially performed. Then, the working film (base film / metal reflective layer / blackening layer / metal oxide layer) is wound around the winding roll. In the first sputtering film formation, a metal reflective layer (Al) with a thickness of 75 nm is formed on the first surface of the PET film. In the subsequent second sputtering film formation, a blackening layer (In2O3 + Cu) with a thickness of 25 nm is formed on the metal reflective layer. In the subsequent third sputtering film formation, a metal oxide layer (ITO) with a thickness of 20 nm is formed on the blackening layer. The conditions for each sputtering film formation are as follows.

[0102] In the first sputtering film formation, the inside of the sputtering film formation apparatus (evacuation chamber, first to third film formation chambers, winding chamber) is evacuated, and then argon (Ar) is introduced into the first film formation chamber, and the pressure in the first film formation chamber is set to 0.3 to 0.4 Pa. As the target, an Al target (manufactured by Mitsui Kinzoku) is used. As the power source for applying voltage to the target, a DC power source is used. The film formation temperature (the temperature of the base film on which the Al layer is laminated) is set to 40°C. Regarding the type of sputtering gas, the pressure in the film formation chamber, the type of power source, and the film formation temperature, they are the same in the second sputtering film formation and the third sputtering film formation.

[0103] In the second sputtering film formation, as the target, a black inorganic target (product name: "DIABLA12", a mixed target of indium oxide (In2O3) and copper (Cu), with an In ratio of 67.3 (±3) mass%, manufactured by Mitsubishi Materials Corporation) was used.

[0104] In the third sputtering film formation, as the target, an ITO target (a composite oxide of indium oxide and tin oxide, with a tin oxide concentration of 10 mass%, manufactured by Mitsui Kinzoku) was used.

[0105] Next, a curable resin composition was coated on the metal oxide layer using a gravure roll to form a coating film. The curable resin composition contains 100 parts by mass of an ultraviolet curable acrylic urethane resin (product name: "AICAAITRON Z - 844", manufactured by AICA Kogyo), 1.0 part by mass of anti-blocking (AB) particles (product name: "SSX103", crosslinked polymethacrylate particles, average particle diameter (D50) of 3.0 μm, manufactured by Sekisui Chemical Co., Ltd.), and methyl ethyl ketone as a solvent. Table 1 shows the composition of the curable resin composition excluding methyl ethyl ketone as the solvent. Next, the coating film was dried and then cured by ultraviolet irradiation to form a cured resin layer with a thickness of 1 μm.

[0106] As described above, the reflective film of Example 1 was produced. As shown in Table 2, the reflective film of Example 1 includes a base 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). It should be noted that regarding the thickness of the cured resin layer, the thickness after removing the thickness of the AB particles is shown in Table 2. The thicknesses of the above-mentioned metal reflective layer, blackening layer, and metal oxide layer were measured using a field emission transmission electron microscope after manufacturing the reflective film, as described later.

[0107] [Table 1]

[0108]

[0109] [Table 2]

[0110]

[0111] [Examples 2 and 3]

[0112] As shown in Table 1, the average particle diameter (D50) of the AB particles contained in the curable resin composition was changed, and except for this, the reflective films of Examples 2 and 3 were produced in the same manner as the reflective film of Example 1.

[0113] [Comparative Examples 1 to 3]

[0114] As shown in Table 1, the average particle diameter (D50) and the amount of the AB particles contained in the curable resin composition were changed, and other than that, each reflective film of Comparative Examples 1 to 3 was produced in the same manner as the reflective film of Example 1.

[0115] [Measurement / Evaluation]

[0116] [Measurement of thickness using a field emission type transmission electron microscope (FE-TEM)]

[0117] The thicknesses of the metal reflective layer, the blackened layer, and the metal oxide layer in each reflective film of the examples and comparative examples were measured by a field emission type transmission electron microscope (FE-TEM). Specifically, first, samples for cross-sectional observation of each multilayer film of the examples and comparative examples were produced by the FIB micro-sampling method. In the FIB micro-sampling method, an FIB apparatus (product name "FB2200", manufactured by Hitachi) was used, and the acceleration voltage was set to 10 kV. Next, the cross-section of the multilayer film of the sample for cross-sectional observation was observed using FE-TEM, and the thicknesses of the metal reflective layer, the blackened layer, and the metal oxide layer were measured in the observed image. In the above observation, an FE-TEM apparatus (product name "JEM-2800", manufactured by JEOL) was used, and the acceleration voltage was set to 200 kV. The measurement results are shown in Table 2.

[0118] [Arithmetic mean height Sa, maximum height Sz]

[0119] For the outer surface of the cured resin layer in each reflective film of the examples and comparative examples, the arithmetic mean height Sa and the maximum height Sz (ISO25178) were obtained from the three-dimensional image obtained by using a shape analysis laser microscope (product name "VK-X1000", manufactured by KEYENCE Corporation). The measurement results are shown in Table 3.

[0120] [Water contact angle]

[0121] For the outer surface of the cured resin layer in each reflective film of the examples and comparative examples, the water contact angle (pure water contact angle) was examined. Specifically, first, a water droplet was formed by dropping 3.5 μL of distilled water on the outer surface of the cured resin layer of the reflective film. Next, the angle formed by the surface of the water droplet on the cured resin layer and the surface (outer surface) of the cured resin layer was measured. The measurement was performed using a contact angle measurement apparatus (product name "FACE CA-X type", manufactured by Kyowa Interface Science Co., Ltd.). Regarding the measurement conditions, the temperature was set to 23°C, and the relative humidity was set to 50%. The measurement results are shown in Table 3.

[0122] [Adhesion]

[0123] For each of the reflective films of the examples and comparative examples, the adhesion between the outer surface of the cured resin layer and the adhesive was examined as described below.

[0124] First, a sample film (length 100 mm × width 25 mm) was cut out from the reflective film. Next, the outer surface side of the cured resin layer of the sample film was bonded to a glass plate via a double-sided tape (product name “No. 5000”, manufactured by Nitto Denko Corporation). Next, a 180° peel test was performed to peel the sample film from the double-sided tape on the glass plate in the length direction thereof, and the force required for peeling (peel force) was measured. A tensile testing machine (product name “TCM-1kNB”, manufactured by NMB Minebea Co., Ltd.) was used in this measurement. In this measurement, the measurement temperature was set to 23°C, the relative humidity was set to 50%, the angle at which the sample film was peeled from the glass plate was set to 180°, and the tensile speed was set to 300 mm / min. The measured peel force is shown in Table 3 as the adhesion force (PSA) (N / 25 mm) of the adhesive.

[0125] [Damage evaluation]

[0126] For each of the reflective films of the examples and comparative examples, the difficulty of causing damage to the cured resin layer was examined as described below.

[0127] First, the tip of a rechargeable touch pen for a touch panel (product name “MS-TP22WH”, manufactured by MS Solutions) was slid on the outer surface (exposed surface) of the cured resin layer of the reflective film. In this sliding, the sliding load was set to 300 g, the sliding distance was set to 100 mm, the sliding speed was set to 150 mm / sec, and the number of sliding times was set to 1. Next, light was irradiated onto the sliding portion on the cured resin layer side of the reflective film. As the light source for the light irradiation, an LED light source (product name “MG-845R”, manufactured by GENTOS) was used. Next, it was confirmed visually from the substrate film side of the antireflection film whether the irradiated light passed through the reflective film. Then, the case where no irradiated light was confirmed to pass through was evaluated as “no scar”, and the case where the irradiated light was confirmed to pass through was evaluated as “scar present”. The evaluation results are shown in Table 3.

[0128] [Table 3]

[0129]

[0130] It should be noted that the above invention is provided as an exemplary embodiment of the present invention, but this is merely an example and should not be construed in a limiting sense. Modification examples of the present invention that are obvious to those skilled in the art are included within the scope of the technical solution.

[0131] Industrial applicability

[0132] The reflective film of the present invention can be used, for example, as a reflective film disposed inside the frame portion of a housing in a liquid crystal display device.

Claims

1. A reflective film, which sequentially includes a substrate film, a metal reflective layer, and a cured resin layer in the thickness direction. 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 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.

3. The reflective film according to claim 1, wherein the metal reflective layer is an aluminum layer.

4. The reflective film according to any one of claims 1 to 3, wherein a metal oxide layer is further provided between the metal reflective layer and the cured resin layer.

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

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