Reflective film

Abstract

The invention relates to a reflective film. This reflective film (X) is provided with a base film (10), a metal reflective layer (20) on the base film (10), an inorganic blackening layer (30) on the metal reflective layer (20), and a metal oxide layer (40) on the inorganic blackening layer (30). The inorganic blackened layer (30) is an inorganic blackened layer containing a metal compound and an elemental metal.

Description

Technical Field

[0001] This invention relates to reflective films. Background Technology

[0002] A liquid crystal display device includes: a liquid crystal panel having an image display surface, a backlight emitting light toward the back of the panel, and a housing housing them. The housing has a bezel portion that serves as a frame surrounding the image display surface. A reflective film is disposed on the inner wall surface within the bezel portion. This reflective film is used to prevent light from the backlight from leaking out from the bezel portion (preventing light leakage). Such a reflective film is described, for example, in Patent Document 1 below.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-184443

[0006] Patent Document 1 describes a reflective film comprising, in the thickness direction, a white resin film, a metal reflective layer, and a black ink layer. According to Patent Document 1, the metal reflective layer is formed of a metal such as aluminum. The black ink layer is formed by printing black ink onto the surface of the metal reflective layer on the white resin film. The black ink layer contains a resin binder and a black pigment. The preferred thickness of the black ink layer is 0.5–3 μm. From the viewpoint of preventing pinholes in the black ink layer, it is preferable to stack multiple layers of black ink. In such a reflective film with a black ink layer, the aforementioned light leakage is prevented by utilizing the light reflection of the metal reflective layer and the light blocking effect of the black ink layer.

[0007] However, in the reflective film of Patent Document 1, the black ink layer does not adhere sufficiently to the metal reflective layer.

[0008] Regarding black ink layers containing resin binders, compressive residual stress is easily generated after the layer is formed. In the black ink layer, the compressive residual stress on the exposed side (the side opposite to the metal reflective layer) is greater than the compressive residual stress on the side where the metal reflective layer is fixed. Furthermore, the thicker the black ink layer, the greater the difference in compressive residual stress between the two sides. Moreover, the greater the difference in compressive residual stress between the two sides of the black ink layer, the lower the adhesion of the black ink layer to the metal reflective layer. Delamination easily occurs at locations of insufficient adhesion in the black ink layer. Delamination of the black ink layer impairs the light leakage prevention function of the reflective film.

[0009] On the other hand, it is strongly required that the metal reflective layer of the reflective film be resistant to metal corrosion. This is because it is essential to suppress the degradation of optical properties such as reflectivity caused by metal corrosion within the reflective film. Furthermore, this suppression of metal corrosion is also required for the metal-containing layers outside the metal reflective layer within the reflective film. Summary of the Invention

[0010] The present invention provides a reflective film suitable for ensuring the adhesion of the blackening layer to the metal reflective layer and inhibiting the corrosion of the metal reflective layer and the blackening layer.

[0011] The present invention [1] includes a reflective film comprising: a substrate film; a metal reflective layer on the substrate film; an inorganic blackening layer on the metal reflective layer, the inorganic blackening layer comprising a metal compound and a single metal; and a metal oxide layer on the inorganic blackening layer.

[0012] The present invention [2] includes the reflective film described in [1] above, wherein the metal reflective layer is an aluminum layer.

[0013] The present invention [3] includes the reflective film described in [1] or [2] above, wherein the elemental metal is copper.

[0014] The present invention [4] includes the reflective film described in any one of [1] to [3] above, wherein the metal oxide layer is an indium oxide layer.

[0015] The present invention [5] includes the reflective film described in any one of [1] to [4] above, wherein the thickness of the metal oxide layer is 5 nm or more.

[0016] The present invention [6] includes the reflective film described in any one of [1] to [5] above, wherein a cured resin layer is further provided on the side of the metal oxide layer opposite to the inorganic blackening layer.

[0017] Invention Effects

[0018] The reflective film of the present invention comprises, as described above, a substrate film, a metal reflective layer on the substrate film, an inorganic blackening layer comprising a metal compound and a single metal on the metal reflective layer, and a metal oxide layer on the inorganic blackening layer. The inorganic blackening layer, comprising a metal compound and a single metal, is suitable for forming a thin film using a dry coating method. The thinner the inorganic blackening layer, the lower the difference in compressive residual stress generated on both sides of the thickness direction in the inorganic blackening layer after film formation. This reduction in the difference in compressive residual stress in the inorganic blackening layer helps ensure the tight adhesion of the inorganic blackening layer to the metal reflective layer. Furthermore, the presence of a metal oxide layer on the inorganic blackening layer in the reflective film is suitable for inhibiting water vapor penetration from the side opposite to the substrate film into the metal reflective layer and the inorganic blackening layer. By inhibiting water vapor penetration, corrosion such as galvanic corrosion is inhibited in the single metal in the inorganic blackening layer and the metal reflective layer. Therefore, the reflective film of the present invention is suitable for ensuring the adhesion of the inorganic blackening layer to the metal reflective layer and for inhibiting the corrosion of the metal reflective layer and the inorganic blackening layer. Attached Figure Description

[0019] Figure 1 This is a cross-sectional schematic diagram of one embodiment of the reflective film of the present invention.

[0020] Figures 2A to 2D express Figure 1 The method for manufacturing the reflective film shown. Figure 2A This refers to the process of forming a metal reflective layer on a substrate film. Figure 2B This refers to the process of forming an inorganic blackening layer on a metallic reflective layer. Figure 2C This refers to the process of forming a metal oxide layer on an inorganic blackening layer. Figure 2D This refers to the process of forming a cured resin layer on a metal oxide layer.

[0021] Figure 3 This is a schematic cross-sectional view of a modified example of the reflective film of the present invention. In this modified example, there is no cured resin layer on the metal oxide layer.

[0022] Explanation of reference numerals in the attached figures

[0023] X: Reflective film; H: Thickness direction; 10: Substrate film; 11: First side; 12: Second side; 20: Metal reflective layer; 30: Inorganic blackening layer; 40: Metal oxide layer; 50: Cured resin layer. Detailed Implementation

[0024] A reflective film X according to one embodiment of the present invention is as follows: Figure 1 The structure shown comprises, sequentially along the thickness direction H, a substrate film 10, a metal reflective layer 20, an inorganic blackening layer 30, a metal oxide layer 40, and a cured resin layer 50. The reflective film X extends in a direction orthogonal to the thickness direction H (plane direction). The reflective film X is, for example, a reflective film that prevents light from the backlight of the liquid crystal display device from leaking out of the housing.

[0025] The substrate film 10 is a substrate that ensures the strength of the reflective film X. The substrate film 10 has a first surface 11 and a second surface 12 opposite to the first surface 11. Furthermore, the substrate film 10 is, for example, a flexible, transparent resin film. Examples of materials for the substrate film 10 include: polyester resin, polyolefin resin, acrylic resin, polycarbonate resin, polyethersulfone resin, polyaryl ester 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 cyclic olefin polymers. Examples of acrylic resins include: polymethacrylate. From the viewpoint of transparency and strength, the material of the substrate film 10 is preferably polyester resin, and more preferably PET.

[0026] From the viewpoint of ensuring meaningful light reflectivity of the substrate film 10, the substrate film 10 is preferably a white film. A white film is obtained, for example, by containing particles such as inorganic fillers that cause light scattering in a resin film. Examples of materials that can be used as such particles include titanium oxide, calcium carbonate, barium sulfate, silica, and talc, with at least one selected from the group consisting of titanium oxide and silica being preferred. These particles can be used alone or in combination of two or more. The average particle size 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 of these 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 further, for example, 50% by mass or less, preferably 40% by mass or less.

[0027] From the viewpoint of suppressing water vapor from the substrate film 10 side of the reflective film X into the metal reflective layer 20 and the inorganic blackening layer 30, and from the viewpoint of the strength of the reflective film X, 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 ensuring the operability of the substrate film 10 in a roll-to-roll manner, 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.

[0028] From the viewpoint of ensuring the adhesion of the metal reflective layer 20 to the substrate film 10, the first surface 11 of the substrate film 10 may also be subjected to surface modification treatment. Examples of surface modification treatments include: corona treatment, plasma treatment, ozone treatment, primer treatment, glow treatment, and coupling agent treatment.

[0029] The metal reflective layer 20 is disposed on the first surface 11 of the substrate film 10. That is, the metal reflective layer 20 is in contact with the first surface 11.

[0030] The metal reflective layer 20 is formed of a metal with light reflectivity. Examples of metals that can 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 to visible light, aluminum or silver is preferred as the metal reflective layer 20. That is, the metal reflective layer 20 is an aluminum layer or a silver layer.

[0031] From the viewpoint of ensuring the light reflectivity of the metal reflective layer 20 and the reflective film X, the thickness of the metal reflective layer 20 is preferably 30 nm or more, more preferably 50 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 substrate film 10, the thickness of the metal reflective layer 20 is preferably 500 nm or less, more preferably 300 nm or less, even more preferably 200 nm or less, even more preferably 150 nm or less, and even more preferably 120 nm or less.

[0032] The inorganic blackening layer 30 is disposed on the metal reflective layer 20. That is, the inorganic blackening layer 30 is in contact with the metal reflective layer 20.

[0033] The inorganic blackening layer 30 is an inorganic layer with high light absorption, containing metal compounds and elemental metals. The inorganic blackening layer 30 may also contain multiple metal compounds or elemental metals.

[0034] The metal compound is a compound of metals and nonmetals. Examples of metal compounds include metal oxides, metal nitrides, and metal carbides. Metal oxides are preferred. Examples of metals (first metals) 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.

[0035] Examples of elemental metals (second metals) 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, these multiple elemental metals preferably include metals different from the first metal.

[0036] From the viewpoint of achieving high light-shielding properties in the inorganic blackening layer 30, the proportion of the first metal in the inorganic 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. From the viewpoint of achieving high light-shielding properties in the inorganic blackening layer 30, the proportion of the second metal in the inorganic 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.

[0037] From the viewpoint of achieving high light-shielding properties in the inorganic blackening layer 30, the inorganic blackening layer 30 preferably contains a metal oxide as a metal compound and contains an elemental metal, more preferably containing indium oxide as a metal compound and copper as an elemental metal. When the inorganic blackening layer 30 contains indium oxide and copper, from the viewpoint of achieving high light-shielding properties in the inorganic blackening layer 30, the proportion of In in the inorganic 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. When the inorganic blackening layer 30 contains indium oxide and copper, from the viewpoint of achieving high light-shielding properties in the inorganic blackening layer 30, the proportion of Cu in the inorganic 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.

[0038] From the viewpoint of ensuring the adhesion of the inorganic blackening layer 30 to the substrate (the metal reflective layer 20 in this embodiment), the thickness of the inorganic blackening layer 30 is preferably 400 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less, and even more preferably 110 nm or less. From the viewpoint of ensuring the light-shielding properties of the inorganic blackening layer 30 and the reflective film X, the thickness of the inorganic blackening layer 30 is preferably 5 nm or more, more preferably 10 nm or more, even more preferably 20 nm or more, even more preferably 30 nm or more, and particularly preferably 50 nm or more.

[0039] From the viewpoint of ensuring the light-shielding properties of the inorganic blackening layer 30 and the reflective film X, the visual transmittance (Y value) of the inorganic blackening layer 30 in the CIE-XYZ color system at wavelengths of 380 nm to 780 nm is preferably 0.1% or less, more preferably 0.05% or less, and even more preferably 0.03% or less. This visual transmittance is, for example, 0.001% or more, 0.005% or more, or 0.01% or more. The visual transmittance can be measured, for example, using a spectrophotometer (product name "U-4100", manufactured by Hitachi High-Tech Science Co., Ltd.)

[0040] In this embodiment, the inorganic blackening layer 30 is a film formed by a dry coating method (dry coating film). Examples of dry coating films include sputtered films formed by sputtering and vapor-deposited films formed by vapor deposition, with sputtered films being preferred.

[0041] The metal oxide layer 40 is disposed on the inorganic blackening layer 30. That is, the metal oxide layer 40 is in contact with the inorganic blackening layer 30.

[0042] Examples of metals 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, it is preferable that the metal oxide is at least one selected from the group consisting of In, Zn, Sn, Mg, Ni, Co, and Cr, and more preferably that the metal oxide layer 40 is indium tin oxide (ITO).

[0043] 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 5 nm or more, more preferably 8 nm or more, and even more preferably 10 nm or more. From the viewpoint of ensuring the adhesion of the metal oxide layer 40 to the inorganic blackening layer 30, 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.

[0044] In this embodiment, 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 a hard coating that is not easily scratched on the reflective film X.

[0045] The cured resin layer 50 is a cured product of the curable resin composition. The curable resin composition contains a curable resin. Examples of curable resins include: polyester resins, urethane acrylate resins, acrylic resins (excluding urethane acrylate resins), urethane resins (excluding urethane acrylate resins), amide resins, silicone resins, epoxy resins, and melamine resins. These curable resins can be used alone or in combination of two or more. From the viewpoint of ensuring high hardness of the cured resin layer 50, it is preferable to use at least one selected from the group consisting of urethane acrylate resins and acrylic resins as the curable resin.

[0046] Furthermore, examples of curable resins include ultraviolet-curable resins and thermosetting resins. From the viewpoint that curing without high-temperature heating helps improve the manufacturing efficiency of the reflective film X, ultraviolet-curable resins are preferred as curable resins.

[0047] The curable resin composition may also contain particles. Examples of particles include inorganic oxide particles and organic particles. Examples of materials that can be used as inorganic oxide particles include: silica, alumina, titanium dioxide, zirconium oxide, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide. Examples of materials that can be used as organic particles include: polymethyl methacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine, melamine, and polycarbonate. Particles may be used alone or in combination of two or more. Inorganic oxide particles are preferred, and at least one selected from silica particles and zirconium oxide particles is more preferred.

[0048] From the viewpoint of ensuring the hardness of the cured resin layer 50, the average particle size (D50) is preferably 20 nm or more, more preferably 25 nm or more, and even more preferably 30 nm or more. From the viewpoint of uniform dispersion of particles within the cured resin layer 50, the average particle size (D50) is preferably 300 nm or less, more preferably 100 nm or less. The average particle size (D50) is the median particle size in the volumetric particle size distribution (the particle size at which the volumetric cumulative frequency reaches 50% from the small diameter side), and is determined, for example, based on the particle size distribution obtained by laser diffraction / scattering.

[0049] From the viewpoint of ensuring the hardness of the cured resin layer 50, the proportion of particles in the cured resin layer 50 is preferably 5% by mass or more, more preferably 8% by mass or more, and even more preferably 10% by mass or more. From the viewpoint of uniform dispersion of particles within the cured resin layer 50, the proportion of particles in the cured resin layer 50 is preferably 30% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0050] 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, and even more preferably 0.7 μm or more. From the viewpoint of ensuring the adhesion of the cured resin layer 50 to 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, even more preferably 2 μm or less, and even more preferably 1.5 μm or less.

[0051] From the viewpoint of ensuring the light leakage prevention properties of the reflective film X as described later, the visual reflectance (Y value) of the reflective film X in the CIE-XYZ color system with wavelengths of 380 nm to 780 nm is preferably 80% or more, more preferably 82% or more, and even more preferably 85% or more. This visual reflectance is, for example, 90% or less, 95% or less, or 100% or less. The visual reflectance (Y value) of the reflective film X refers to the reflectance of light irradiated onto the reflective film X from the substrate film 10 side.

[0052] From the viewpoint of ensuring the light leakage prevention property of the reflective film X as described later, the visual transmittance (Y value) of the reflective film X in the CIE-XYZ color system with wavelengths of 380 nm to 780 nm is preferably 0.10% or less, more preferably 0.05% or less, and even more preferably 0.02% or less. This visual transmittance is, for example, 0.001% or more, 0.005% or more, or 0.01% or more. The visual transmittance (Y value) of the reflective film X refers to the transmittance of light irradiated onto the reflective film X from the substrate film 10 side.

[0053] The reflective film X is manufactured in a roll-to-roll manner, for example, as described below.

[0054] First, such as Figure 2A As shown, a metal reflective layer 20 is formed on the substrate film 10 (metal reflective layer formation process). 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, with sputtering being preferred.

[0055] In sputtering, for example, a sputtering film deposition apparatus capable of performing film deposition processes in a roll-to-roll manner is used. Specifically, in sputtering, a sputtering gas (inert gas) is introduced into the film deposition chamber of the sputtering film deposition apparatus under vacuum conditions, and a negative voltage is applied to a target disposed on a cathode within the film 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 the target material from the target surface, and depositing the ejected target material onto the substrate film 10.

[0056] The material of the target disposed on the cathode within the film-forming chamber (i.e., the material of the metal reflective layer 20) is the metal described above for the metal reflective layer 20. The gas pressure within the film-forming chamber during sputtering (sputter film formation) is, for example, 0.02 Pa or more, and further, for example, 1 Pa or less. Examples of power sources for applying voltage to the target include: DC power, AC power, MF power, and RF power (also as described later in the sputter film formation concerning the inorganic blackening layer 30 and the metal oxide layer 40). The absolute value of the discharge voltage during sputter film formation is, for example, 50 V or more, and further, for example, 500 V or less (also as described later in the sputter film formation concerning the inorganic blackening layer 30 and the metal oxide layer 40).

[0057] Next, as Figure 2B As shown, an inorganic blackening layer 30 is formed on the metal reflective layer 20 (inorganic blackening layer formation process). Specifically, the inorganic blackening layer 30 is formed by dry coating of a material onto the metal reflective layer 20. Examples of dry coating methods include sputtering and vapor deposition, with sputtering being preferred.

[0058] The material of the target disposed on the cathode in the sputtering process (i.e., the material of the inorganic blackening layer 30) is, for example, the sintered body containing a metal compound and a single metal as described above regarding the inorganic blackening layer 30. The gas pressure in the film-forming chamber during the sputtering film formation of the inorganic blackening layer 30 is, for example, 0.02 Pa or more, and furthermore, for example, 1 Pa or less.

[0059] By using a dry coating method, the inorganic blackening layer 30 can be formed thinner than the aforementioned black ink layer containing resin components. In such a thin inorganic blackening layer 30, the difference between the compressive residual stress on the side fixed to the metal reflective layer 20 and the compressive residual stress on the opposite side of the metal reflective layer 20 is small (the thinner the inorganic blackening layer 30, the smaller the difference in compressive residual stress between the two sides). Furthermore, the small difference in compressive residual stress between the two sides in the thickness direction H of the inorganic blackening layer 30 helps ensure the tight adhesion of the inorganic blackening layer 30 to the metal reflective layer 20.

[0060] Next, as Figure 2C As shown, a metal oxide layer 40 is formed on the inorganic blackening layer 30 (metal oxide layer formation process). Specifically, the metal oxide layer 40 is formed by dry coating of a material onto the inorganic blackening layer 30. Examples of dry coating methods include sputtering and vapor deposition, with sputtering being preferred.

[0061] The material of the target disposed on the cathode in the sputtering process (i.e., the material of the metal oxide layer 40) is, for example, a sintered body of the metal oxide described above for the metal oxide layer 40. The gas pressure in the film-forming chamber during the sputtering film formation of the metal oxide layer 40 is, for example, 0.02 Pa or more, and furthermore, for example, 1 Pa or less.

[0062] The series of processes from the metal reflective layer formation step to the metal oxide layer formation step are carried out using a single pass line while the working film is transported in a roll-to-roll manner. In this single-pass line process, the working film is never released into the atmosphere. After the metal reflective layer 20 is formed, not releasing the working film into the atmosphere, but instead sequentially forming the inorganic blackening layer 30 and the metal oxide layer 40 on the metal reflective layer 20, helps ensure the adhesion of the inorganic blackening layer 30 and the metal oxide layer 40 to the metal reflective layer 20.

[0063] Next, as Figure 2D As shown, a curable resin layer 50 is formed on the metal oxide layer 40 (curable resin layer formation process). The curable resin layer 50 can be formed by coating the metal oxide layer 40 with the above-described curable resin composition, forming a coating film, and then curing the coating film. If the curable resin composition contains an ultraviolet-curable resin, the coating film is cured by ultraviolet irradiation. If the curable resin composition contains a thermosetting resin, the coating film is cured by heating.

[0064] As described above, reflective film X can be manufactured.

[0065] The reflective film X can also be like Figure 3 The reflective film X shown does not have a cured resin layer 50. Such a reflective film X can be produced without performing the aforementioned cured resin layer formation process ( Figure 2D To ensure scratch resistance on the side of the reflective film X opposite to the second surface 12, the reflective film X preferably has a cured resin layer 50.

[0066] The reflective film X, as described above, comprises: a substrate film 10, a metal reflective layer 20 on the substrate film 10, an inorganic blackening layer 30 comprising a metal compound and a single metal on the metal reflective layer 20, and a metal oxide layer 40 on the inorganic blackening layer 30. The inorganic blackening layer 30, comprising a metal compound and a single metal, is suitable for being formed into a thin film using a dry coating method. The thinner the inorganic blackening layer 30, the lower the difference in compressive residual stress generated on both sides of the thickness direction in the inorganic blackening layer 30 after film formation. This reduction in the difference in compressive residual stress of the inorganic blackening layer 30 helps ensure the adhesion of the inorganic blackening layer 30 to the metal reflective layer 20.

[0067] Furthermore, the reflective film X has a metal oxide layer 40 on the inorganic blackening layer 30, which is suitable for inhibiting water vapor from penetrating from the side opposite to the substrate film 10 into the metal reflective layer 20 and the inorganic blackening layer 30. By inhibiting the penetration of water vapor, corrosion such as galvanic corrosion is inhibited in the elemental metal in the inorganic blackening layer 30 and the metal reflective layer.

[0068] Therefore, the reflective film X is suitable for ensuring the tight adhesion of the inorganic blackening layer 30 to the metal reflective layer 20 and inhibiting the corrosion of both the metal reflective layer 20 and the inorganic blackening layer 30. Specifically, as shown in the embodiments described later. Furthermore, the higher the tightness of the adhesion between the inorganic blackening layer 30 and the metal reflective layer 20, the more effectively the inorganic blackening layer 30 is prevented from peeling off, and the better the reflective film X can perform in preventing light leakage.

[0069] Example

[0070] The following examples illustrate the invention in detail. However, the invention is not limited to these examples. Furthermore, the specific values ​​of the compounding amounts (contents), physical property values, parameters, etc., described below can be replaced by the upper limits (values ​​defined as "below" or "less than") or lower limits (values ​​defined as "above" or "greater than") of the corresponding compounding amounts (contents), physical property values, parameters, etc., described in the "Detailed Embodiments" above.

[0071] [Example 1]

[0072] First, a white polyethylene terephthalate (PET) film (product name "Lumirror E20", thickness 38μm, manufactured by Toray) was prepared as the substrate film.

[0073] Next, a metal reflective layer, an inorganic blackening layer, and a metal oxide layer are sequentially formed on one side (first side) of the PET film using a sputtering method (sputtering film deposition process). In this sputtering film deposition process, a roll-to-roll sputtering film deposition apparatus (DC magnetron sputtering film deposition apparatus) is used. This apparatus includes: an extraction chamber, a first film deposition chamber, a second film deposition chamber, a third film deposition chamber, and a winding chamber. The extraction chamber is equipped with an extraction roller. A roll of the aforementioned substrate film, serving as the working film, is mounted on the extraction roller. The winding chamber is equipped with a winding roller capable of winding the working film. In the first to third film deposition chambers, the working film can be moved from the extraction chamber to the winding chamber in a roll-to-roll manner, and the film deposition process is performed.

[0074] In the sputtering film deposition process, specifically, a first sputtering film deposition in a first film deposition chamber, a second sputtering film deposition in a second film deposition chamber, and a third sputtering film deposition in a third film deposition chamber are performed sequentially. Then, a working film (substrate film / metal reflective layer / inorganic blackening layer / metal oxide layer) is wound up by a winding roller in a winding chamber. In the first sputtering film deposition, a 75 nm thick metal reflective layer (Al) is formed on the first surface of the PET film. Next, in the second sputtering film deposition, a 30 nm thick inorganic blackening layer (In₂O₃+Cu) is formed on the metal reflective layer. Then, in the third sputtering film deposition, a 20 nm thick metal oxide layer (ITO) is formed on the inorganic blackening layer. Each sputtering film deposition is specifically described below.

[0075] In the first sputtering deposition process, after vacuum venting of the sputtering apparatus (extraction chamber, first to third deposition chambers, and winding chamber), argon gas (Ar) as the sputtering gas was introduced into the first deposition chamber, and the gas pressure in the first deposition chamber was set to 0.3–0.4 Pa. An Al target (manufactured by Mitsui Metals Corporation) 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 to which the Al layers are stacked) was set to 40°C. The type of power source and the deposition temperature were the same in the second and third sputtering deposition processes.

[0076] In the second sputtering film deposition, after the aforementioned vacuum venting of the sputtering film deposition apparatus, Ar, as the sputtering gas, is introduced into the second film deposition chamber, and the gas pressure in the second film deposition chamber is set to 0.3 to 0.4 Pa. Furthermore, a black inorganic target (product name "DIABLA12", a mixed target of indium oxide (In2O3) and copper (Cu), with an In content of 67.3 (±3) wt%, manufactured by Mitsubishi Materials Co., Ltd.) is used as the target.

[0077] In the third sputtering film deposition process, after the aforementioned vacuum venting of the sputtering film deposition apparatus, Ar, as the sputtering gas, is introduced into the third film deposition chamber, and the gas pressure in the third film deposition chamber is set to 0.3 to 0.4 Pa. Furthermore, an ITO target (a composite oxide of indium oxide and tin oxide, with a tin oxide concentration of 10% by mass, manufactured by Mitsui Metals) is used as the target.

[0078] Next, a curable resin composition is coated onto the metal oxide layer to form a coating film. The curable resin composition contains a UV-curable urethane acrylic resin (product name "AICAAITRON Z844", manufactured by AICA Industries) and methyl ethyl ketone as a solvent. The coating film is then dried and cured by UV irradiation to form a 1 μm thick hard coating (HC) layer.

[0079] As described above, the reflective film of Example 1 was fabricated. The reflective film of Example 1 has a stacked structure comprising a substrate film (PET, 38 μm thick), a metal reflective layer (Al, 75 nm thick), an inorganic blackening layer (In₂O₃+Cu, 30 nm thick), a metal oxide layer (ITO, 20 nm thick), and an HC layer (1 μm thick). In Example 1, the metal reflective layer, inorganic blackening layer, metal oxide layer, and HC layer on the substrate film form a multilayer film.

[0080] [Example 2]

[0081] Except for the following, the reflective film of Example 2 was fabricated in the same manner as the reflective film of Example 1. In the third sputtering deposition process, the thickness of the formed metal oxide layer (ITO) was set to 10 nm.

[0082] [Comparative Example 1]

[0083] Except for the following, the reflective film of Comparative Example 1 was fabricated in the same manner as the reflective film of Example 1. In the sputtering deposition process, a third sputtering deposition was not performed. That is, no metal oxide layer was formed on the inorganic blackening layer. In Comparative Example 1, a multilayer film was formed on the substrate film consisting of a metal reflective layer, an inorganic blackening layer, and an HC layer.

[0084] [Comparative Example 2]

[0085] Except as described below, the reflective film of Comparative Example 2 was fabricated in the same manner as the reflective film of Example 1. In the sputtering deposition process, a first sputtering deposition, a third sputtering deposition, and a second sputtering deposition were performed sequentially. That is, a metal reflective layer, a metal oxide layer, and an inorganic blackening layer were sequentially formed on the substrate film. In Comparative Example 2, the metal reflective layer, the metal oxide layer, the inorganic blackening layer, and the HC layer on the substrate film formed a multilayer film.

[0086] [Comparative Example 3]

[0087] Except for the following, the reflective film of Comparative Example 3 was fabricated in the same manner as the reflective film of Example 1. In the third sputtering deposition process, an AlNx layer was formed instead of the ITO layer. In this third sputtering deposition, after vacuum degassing of the sputtering apparatus, Ar as a sputtering gas and nitrogen (N2) as a reactive gas were introduced into the third deposition chamber, and the pressure in the third deposition chamber was set to 0.3–0.4 Pa. The amount of N2 introduced into the third deposition chamber was set to 1 part by volume for every 15 parts by volume of Ar introduced (the flow rate ratio of Ar to N2 was 15:1). Furthermore, an Al target (manufactured by Mitsui Metals Corporation) was used as the target. In Comparative Example 3, a multilayer film was formed on the substrate film consisting of a metal reflective layer, an inorganic blackening layer, an AlNx layer, and an HC layer.

[0088] <Thickness of each layer>

[0089] The thicknesses of each layer (metallic reflective layer, inorganic blackening layer, metal oxide layer, and AlNx layer) in the reflective films of Examples 1, 2, and Comparative Examples 1-3 were determined by field emission transmission electron microscopy (FE-TEM). Specifically, firstly, cross-sectional observation samples of each multilayer film of Examples 1, 2, and Comparative Examples 1-3 were prepared using the FIB microsampling method. In the FIB microsampling method, an FIB device (product name "FB2200", manufactured by Hitachi) was used, and the accelerating voltage was set to 10 kV. Next, the cross-sections of the multilayer films in the cross-sectional observation samples were observed using FE-TEM, and the thicknesses of the metallic reflective layer, inorganic blackening layer, metal oxide layer (Examples 1, 2, and Comparative Example 2), and AlNx layer (Comparative Example 3) were measured in the observed images. In this observation, an FE-TEM device (product name "JEM-2800", manufactured by JEOL) was used, and the accelerating voltage was set to 200 kV. The measurement results are shown in Table 1.

[0090] <Visual transmittance>

[0091] The perceived transmittance of each reflective film in Examples 1 and 2, and Comparative Examples 1 to 3, was measured. Specifically, it is described below.

[0092] First, a film for measurement (the first film) is cut from the reflective film. Next, the visual transmittance of the first film is measured using a spectrophotometer (product name "U-4100", manufactured by Hitachi High-Tech Science). This transmittance is the visual transmittance (Y value) of transmitted light with wavelengths from 380 nm to 780 nm in the CIE-XYZ colorimetric system for the first film. In this measurement, the first film is placed inside the spectrophotometer such that light is irradiated from the substrate film side of the first film. The measurement results are shown in Table 1.

[0093] <Visual reflectance>

[0094] The visual reflectivity of each reflective film in Examples 1 and 2, and Comparative Examples 1 to 3, was measured. Specifically, it is described below.

[0095] First, the side of the reflective film opposite to the substrate film side is bonded to a black acrylic sheet using a specified adhesive. This yields a laminated film. Next, a measurement sheet (second film) is cut from the laminated film. Then, the perceived reflectance of the second film is measured using a spectrophotometer (product name "U-4100", manufactured by Hitachi High-Tech Science). This reflectance is the perceived reflectance (Y value) of light irradiated onto the second film at wavelengths of 380 nm to 780 nm in the CIE-XYZ colorimetric system. In this measurement, the second film is placed inside the spectrophotometer such that light irradiates the second film from the substrate film side. The measurement results are shown in Table 1.

[0096] <Peeling Test>

[0097] The adhesion of the inorganic blackening layer of each reflective film of Examples 1, 2 and Comparative Examples 1 to 3 was investigated as follows.

[0098] First, sample films are fabricated for each reflective film. In the fabrication of the sample films, firstly, film sheets (50mm × 50mm) are cut from the reflective film. Next, 11 parallel first slits (1mm intervals) extending linearly in a first direction and 11 parallel second slits (1mm intervals) extending linearly in a second direction orthogonal to the first direction are formed on the multilayer film within the film sheet, creating 100 squares. This yields the sample film. Each slit extends from the exposed surface of the multilayer film to the substrate film in the thickness direction.

[0099] Next, a peel test (checkerboard peel test) was performed on each sample film according to JIS K 5400. Specifically, firstly, a prescribed single-sided adhesive tape was applied to the multilayer film surface of the sample film, covering all 100 squares. Then, the adhesive tape was peeled off along a first direction. The squares after the adhesive tape was peeled off were then observed to confirm whether any squares had peeled off. In each reflective film of Examples 1, 2, and Comparative Examples 1-3, the number of squares with at least some peeling was 0 (no peeling occurred in any square).

[0100] <Corrosion Test>

[0101] The first corrosion test was carried out on each reflective film of Examples 1, 2 and Comparative Examples 1 to 3 as described below.

[0102] First, a sample film (210mm × 297mm) was cut from the reflective film. Next, under conditions where the sample film was irradiated with 2000 lux of light from the PET film side, the multilayer film side of the sample film was observed, and defects with a maximum length of 500 μm or more in the non-surface direction were confirmed (first confirmation step). The defects in this test refer to optical pinholes in the aforementioned multilayer film, which are light-permeable structures including a highly reflective metallic reflective layer and a highly opaque inorganic blackening layer. These pinholes are formed when the optical properties of the corroded areas deteriorate due to localized corrosion of the metallic components. Visual observation and, if necessary, optical microscopy were performed. Next, the sample film was left to stand for 72 hours at a temperature of 65°C and a relative humidity of 90% (standing step). Then, under conditions where the sample film was irradiated with 2000 lux of light from the PET film side, the multilayer film side of the sample film was observed, and defects with a maximum length of 500 μm or more in the non-surface direction were confirmed (second confirmation step). As part of the observation, visual observation and optical microscopy observation were performed as needed. Then, regarding the corrosion resistance of the reflective film, cases where defects larger than 500 μm were not detected in the second confirmation step were evaluated as "good," and cases where defects larger than 500 μm were detected were evaluated as "poor." The evaluation results are shown in Table 1.

[0103] The settling time in the settling step was changed to 240 hours, and the second corrosion test was performed in the same manner as the first corrosion test. The evaluation results of the second corrosion test are shown in Table 1. Furthermore, the settling time in the settling step was changed to 500 hours, and the third corrosion test was performed in the same manner as the first corrosion test. The evaluation results of the third corrosion test are also shown in Table 1.

[0104] [Table 1]

[0105]

[0106] It should be noted that the above-described invention is provided as an example of the present invention, but it is merely an example and not intended to be limiting. Modifications of the invention that are apparent to those skilled in the art are also included in the claims.

[0107] Industrial availability

[0108] The reflective film X of the present invention is preferably used in liquid crystal display devices and the like, and can suppress light from the backlight source from leaking out of the housing.

Claims

1. A reflective film comprising: Base film; A metal reflective layer on the substrate film; An inorganic blackening layer on the metal reflective layer, wherein the inorganic blackening layer comprises a metal compound and a single metal; and A metal oxide layer on the inorganic blackening layer.

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

3. The reflective film according to claim 1, wherein The elemental metal is copper.

4. The reflective film according to claim 1, wherein: The metal oxide layer is an indium oxide layer.

5. The reflective film according to claim 1, wherein The thickness of the metal oxide layer is greater than 5 nm.

6. The reflective film according to any one of claims 1 to 5, wherein The metal oxide layer further includes a cured resin layer on the side opposite to the inorganic black layer.

Images