Optical laminate and article

Abstract

To provide an optical laminate with high infrared transmission factor, excellent in a reflective hue, and applicable to a display device having a curved surface shape.SOLUTION: An antireflection film includes a film base material and an optical functional layer. The optical functional layer includes, sequentially from a film base material side: a first high refractive index layer with optical thickness of 25 to 43 nm, inclusive; a first low refractive index layer with optical thickness of 54 to 69 nm, inclusive; a second high refractive index layer with optical thickness of 278 to 308 nm, inclusive; and a second low refractive index layer with optical thickness of 131 to 141 nm, inclusive. In the antireflection film, a transmission factor of light at wavelength 940 nm is 86% or more, a luminous reflectance Y is 1.0% or less and an a* value is -4.0<a*<4.0 and a b* value is -15.0<b*<0.0 in a CIE-LAB colorimetric system of total reflected light when light of wavelength 380 to 780 nm is incident from a standard light source D65.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to optical laminates and articles. [Background technology]

[0002] Antireflection films known from Patent Documents 1 to 3, etc., are applied to various devices to prevent surface reflection. For example, they are applied to in-vehicle films such as head-up displays, and display devices such as smartphone touch panels. It is desirable that optical laminates such as antireflection films, when attached to a display device, are less likely to color the light reflected by the display device or the like. In other words, it is desirable that color unevenness is not visible even when the user changes the viewing angle of the display device. In response to this demand, development is underway on optical laminates that have minimal color unevenness when the viewing angle changes (for example, Patent Document 1).

[0003] The optical laminate of Patent Document 2 is said to include a laminate in which layers of a low refractive index material and layers of a high refractive index material are alternately stacked on a glass substrate. The optical laminate of Patent Document 2 is formed by sputtering an optical function layer onto the glass substrate.

[0004] Furthermore, an infrared sensor (IR sensor) that responds to infrared rays may be installed on the front surface of a display device, etc. Therefore, an optical laminate such as an anti-reflection film provided on the front surface of a display device, etc., that has a high infrared transmittance is desired, and development is underway (for example, Patent Document 3).

[0005] Furthermore, in recent years, curved display devices have become widespread from the viewpoints of improved functionality and design, which reduce strain on the user's eyes while also enhancing the sense of immersion, taking into account the distance from the user's eyes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6956909 [Patent Document 2] Patent No. 6881172 [Patent Document 3] Patent No. 7121070 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the optical laminate of Patent Document 1 does not take into consideration that an infrared sensor will be provided in the display device, and therefore has low infrared transmittance. Therefore, in a display device formed with the optical laminate of Patent Document 1, the IR sensor may not function properly.

[0008] Furthermore, the optical laminate of Patent Document 2 has an optical functional layer formed on a chemically strengthened glass substrate approximately 2 mm thick. This, coupled with the low flexibility of glass substrates, makes it unsuitable for curved display devices. If a curved display device were to be fabricated using a glass substrate having the aforementioned thickness, the glass substrate would need to be bent before the optical functional layer is deposited. However, if the glass substrate is bent, the distance from the deposition target to the glass substrate would be uneven when the optical functional layer is formed on the substrate by sputtering. This raises concerns about reduced in-plane uniformity of the formed optical functional layer. Reduced in-plane uniformity of the optical functional layer is thought to result in in-plane variations in the optical properties of the optical laminate, such as infrared transmittance and hue at varying viewing angles.

[0009] Furthermore, the optical laminate as disclosed in Patent Document 3 may not have a good hue due to total reflection, or color unevenness may be visible depending on the viewing angle.

[0010] There is no known optical laminate that has high infrared transmittance, good total reflection hue, and is applicable to display devices with curved surfaces. In an optical laminate, the configurations of the individual layers interact with each other to determine the overall characteristics, and there is a need for the development of an optical laminate with a new configuration that can achieve both of the above characteristics.

[0011] The present invention is an invention made in view of the above circumstances, and an object thereof is to provide an optical laminate having a high infrared transmittance, a good total reflection hue, and being applicable to a display device having a curved surface shape, and an article provided with the optical laminate.

Means for Solving the Problems

[0012] In order to solve the above problems, the present inventors provide the following means.

[0013] (1) An optical laminate according to one aspect of the present invention is an antireflection film including a film base material and an optical functional layer formed on the film base material, wherein the optical functional layer includes, in order from the film base material side, a first high refractive index layer having an optical thickness of 25 nm or more and 43 nm or less, a first low refractive index layer having an optical thickness of 54 nm or more and 69 nm or less, a second high refractive index layer having an optical thickness of 276 nm or more and 308 nm or less, and a second low refractive index layer having an optical thickness of 128 nm or more and 141 nm or less, wherein the transmittance of light at a wavelength of 940 nm is 86% or more, the visual reflectance Y is 1.0% or less, and when light having a wavelength of 380 nm to 780 nm from a standard light source D65 is incident, the a* value in the CIE-LAB color system of the total reflected light is -4.0 < a* < 4.0, and the b* value is -15.0 < b* < 0.0.

[0014] (2) In the optical laminate of (1) above, when light having a wavelength of 380 nm to 780 nm from a standard light source D65 is incident on the surface at an incident angle of 5° to 50°, the a* value in the CIE-LAB color system of the regular reflected light may be -4.0 < a* < 4.0, and the b* value may be -15.0 < b* < 6.0.

[0015] (3) In the optical laminate of (1) or (2) above, when light with wavelengths from 380 nm to 780 nm from a standard light source D65 is incident on the surface at an incident angle of 30° to 40°, the a* value in the CIE-LAB color system of the regular reflection light may be -4.0 < a* < 4.0, and the b* value may be -4.0 < b* < 4.0.

[0016] (4) In the optical laminate of (1) to (3) above, the film substrate is made of an organic material, and between the film substrate and the optical functional layer, there are further provided a hard coat layer in contact with the film substrate and an adhesion layer in contact with the hard coat layer and the optical functional layer, and an antifouling layer disposed on the side opposite to the second high refractive index layer of the second low refractive index layer may be further provided.

[0017] (5) In the optical laminate of (1) to (4) above, the optical thickness of the antifouling layer may be 3 nm or more and 13 nm or less.

[0018] (6) An article comprising the optical laminate according to any one of (1) to (5) above.

[0019] (7) In the article of (6) above, the antireflection film may be provided on the surface of an image display device.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide an optical laminate having a high infrared transmittance, a good total reflection hue, and being applicable to a curved surface display device. Further, according to (2) and (3) above, it is possible to provide an optical laminate in which color unevenness is difficult to be visually recognized even when the viewing angle changes.

Brief Description of the Drawings

[0021] [Figure 1] It is a cross-sectional view showing an example of the configuration of an optical laminate according to an embodiment of the present invention. [Figure 2] It is a schematic view showing an example of the configuration of a manufacturing apparatus that can be used in the manufacturing method of an optical laminate according to an embodiment of the present invention. [Figure 3] 1. FIG. 4 is a cross-sectional view showing an example of the configuration of an optical laminate according to a modified example of FIG. [Figure 4] 4 is a schematic diagram showing how the optical laminate of FIG. 3 is bonded to a bonding surface of an object. DETAILED DESCRIPTION OF THE INVENTION

[0022] Hereinafter, this embodiment will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for the sake of convenience in order to make the features of the present invention easier to understand, and the dimensional ratios of each component may differ from the actual ones. The materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not limited to them and can be implemented with appropriate changes within the scope of the effects.

[0023] [Optical laminate] FIG. 1 is a cross-sectional view showing an example of the configuration of an optical laminate according to one embodiment of the present invention. The optical laminate 100 shown in FIG. 1 includes a film substrate 10, a hard coat layer 20, an adhesive layer 30, and an optical functional layer 40, in this order. This optical laminate 100 functions as an anti-reflection film. The optical laminate 100 further includes, for example, an antifouling layer 50 on the optical functional layer 40. The optical functional layer 40 includes, in order from the film substrate 10 side, a first high refractive index layer 41a having an optical thickness of 25 nm to 43 nm, a first low refractive index layer 42a having an optical thickness of 54 nm to 69 nm, a second high refractive index layer 41b having an optical thickness of 278 nm to 308 nm, and a second low refractive index layer 42b having an optical thickness of 131 nm to 141 nm. In this embodiment, the "optical thickness" is the product of the physical thickness and the refractive index. The "refractive index" is measured in accordance with JIS K7105 at a temperature of 25°C and a wavelength of 550 nm. The "physical thickness" can be determined by, for example, measuring the thickness at 20 points on a cross-sectional image taken using a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM), and averaging the values ​​at 20 points.

[0024] The optical laminate 100 has a transmittance of 86% or more for light at a wavelength of 940 nm. The optical laminate 100 has a luminous reflectance Y of 1.0% or less. When light of a wavelength of 380 nm to 780 nm is incident on the optical laminate 100 using a standard light source D65, the a * The value is -4.0 * <4.0, b * The value is -15.0 * <0.0.

[0025] <Film substrate> The film substrate 10 is, for example, a plastic film. Examples of materials constituting the plastic film include polyester-based resins, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, (meth)acrylic-based resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyarylate-based resins, and polyphenylene sulfide-based resins. As described above, the film substrate 10 may be made of an organic material, or may be an inorganic substrate such as a glass film. The film substrate 10 is made of a transparent material that can transmit visible light and infrared light. A triacetyl cellulose (TAC) substrate is preferred as the film substrate 10. When a TAC substrate is used as the film substrate 10 and a hard coat layer 20 is formed on one surface thereof, a permeation layer is formed in which some of the components constituting the hard coat layer 20 have permeated into the TAC substrate. As a result, the adhesion between the film substrate 10 and the hard coat layer 20 is improved, and the occurrence of interference fringes due to the difference in refractive index between the layers is suppressed.

[0026] In addition, in this embodiment, "(meth)acrylic" means methacrylic and acrylic.

[0027] ​​The film substrate 10 may contain a reinforcing material as long as the optical properties are not significantly impaired. Examples of the reinforcing material include cellulose nanofiber and nanosilica. In particular, polyester-based resins, acetate-based resins, polycarbonate-based resins, and polyolefin-based resins are preferably used as the reinforcing material.

[0028] The film substrate 10 may be a film having optical and / or physical functions. Examples of films having optical and / or physical functions include polarizing plates, retardation compensation films, heat-shielding films, transparent conductive films, brightness-enhancing films, and barrier-enhancing films.

[0029] The thickness of the film substrate 10 is 1000 μm or less, for example, 25 μm or more, preferably 40 μm to 500 μm, and preferably 200 μm or less or 150 μm or less. When the thickness of the film substrate 10 is 25 μm or more, wrinkles are less likely to occur even when stress is applied to the optical laminate 100. Furthermore, when the thickness of the film substrate 10 is 25 μm or more, wrinkles are less likely to occur even when the hard coat layer 20 is continuously formed on the film substrate 10, reducing manufacturing concerns. When the thickness of the film substrate 10 is 40 μm or more, wrinkles are even less likely to occur. Furthermore, the film substrate 10 having the above thickness can be attached to a curved attachment surface, as will be described in detail below with reference to FIG. 4, and is applicable to display devices with curved surfaces.

[0030] When production is carried out using a roll, it is preferable that the thickness of the film substrate 10 is thin. This is because the optical laminate 100 during production and the optical laminate 100 after production can be easily wound into a roll, allowing for efficient production of the optical laminate 100. Furthermore, when the thickness of the film substrate 10 is within the above range, it can be easily applied to curved surfaces.

[0031] The surface of the film substrate 10 may be previously subjected to an etching treatment such as sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, chemical conversion, or oxidation, and / or a primer treatment. By previously performing these treatments, adhesion to the hard coat layer 20 to be formed on the film substrate 10 can be improved. Furthermore, before forming the hard coat layer 20 on the film substrate 10, it is also preferable to remove dust and clean the surface of the film substrate 10, as necessary, by subjecting the surface of the film substrate 10 to solvent washing, ultrasonic cleaning, or the like. The film substrate 10 having the above-described configuration also allows the optical laminate 100 including the film substrate 10 to be bonded to a curved surface.

[0032] <Hard coat layer> For example, a hard coat layer 20 and an adhesive layer 30 are formed between the film substrate 10 and the optical functional layer 40. The hard coat layer 20 is a layer that contacts the film substrate 10. The hard coat layer 20 is not particularly limited, and a known hard coat layer can be used. The hard coat layer 20 may contain, for example, a binder resin and a filler. In addition, the hard coat layer 20 may contain a leveling agent.

[0033] The binder resin is preferably transparent, and examples thereof include ionizing radiation curable resins that are cured by ultraviolet light or electron beams, thermoplastic resins, and thermosetting resins.

[0034] Examples of ionizing radiation curable resins that are binder resins include ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, and N-vinylpyrrolidone. The ionizing radiation curable resin may also be a compound having two or more unsaturated bonds. Examples of ionizing radiation curable resins having two or more unsaturated bonds include trimethylolpropane tri(meth)acrylate, tripropylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and dipentaerythritol tetra(meth)acrylate. and polyfunctional compounds such as tetrapentaerythritol penta(meth)acrylate, tripentaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, isocyanuric acid tri(meth)acrylate, isocyanuric acid di(meth)acrylate, polyester tri(meth)acrylate, polyester di(meth)acrylate, bisphenol di(meth)acrylate, diglycerin tetra(meth)acrylate, adamantyl di(meth)acrylate, isobornyl di(meth)acrylate, dicyclopentane di(meth)acrylate, tricyclodecane di(meth)acrylate, and ditrimethylolpropane tetra(meth)acrylate. Among these, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), and pentaerythritol tetraacrylate (PETTA) are preferably used as the binder resin. The term "(meth)acrylate" refers to methacrylate and acrylate. The ionizing radiation curable resin may be one obtained by modifying the above-mentioned compounds with PO (propylene oxide), EO (ethylene oxide), CL (caprolactone), or the like. The ionizing radiation curable resin is preferably an acrylic ultraviolet curable resin composition.

[0035] Examples of thermoplastic resins that serve as binder resins include styrene-based resins, (meth)acrylic resins, vinyl acetate-based resins, vinyl ether-based resins, halogen-containing resins, alicyclic olefin-based resins, polycarbonate-based resins, polyester-based resins, polyamide-based resins, cellulose derivatives, silicone-based resins, and rubber or elastomers. The thermoplastic resins are amorphous and soluble in organic solvents (particularly common solvents that can dissolve multiple polymers and curable compounds). In particular, from the viewpoints of transparency and weather resistance, the binder resin is preferably a styrene-based resin, a (meth)acrylic resin, an alicyclic olefin-based resin, a polyester-based resin, a cellulose derivative (such as a cellulose ester), or the like.

[0036] The thermosetting resin that is the binder resin may be, for example, a phenol resin, a urea resin, a diallyl phthalate resin, a melamine resin, a guanamine resin, an unsaturated polyester resin, a polyurethane resin, an epoxy resin, an aminoalkyd resin, a melamine-urea co-condensation resin, a silicon resin, or a polysiloxane resin (including so-called silsesquioxanes such as cage-shaped and ladder-shaped silsesquioxanes).

[0037] The hard coat layer 20 may contain a light-transmitting organic resin and an inorganic material, or may contain an organic-inorganic hybrid material, in order to provide anti-glare properties, etc. These particles are intended to provide the hard coat layer 20 with a light diffusing function, an anti-glare function by forming surface irregularities, etc. The light-transmitting resin fine particles can be formed from a resin containing a styrene-acrylic monomer copolymer resin (styrene-acrylic copolymer resin), a (meth)acrylic resin, a polystyrene resin, a polyethylene resin, a polycarbonate resin, a vinyl chloride resin, etc.

[0038] The filler may be made of an organic substance, an inorganic substance, or a mixture of organic and inorganic substances. Various fillers can be selected for the hard coat layer 20 depending on the application of the optical laminate 100, from the viewpoints of antiglare properties, adhesion to the optical functional layer 40 described below, antiblocking properties, etc. Specifically, known fillers such as silica (oxide of Si) particles, alumina (aluminum oxide) particles, and organic fine particles can be used as the filler.

[0039] When the filler is silica particles and / or alumina particles, the average particle size of the filler is, for example, 800 nm or less, preferably 100 nm or less, and more preferably 10 nm or more and 70 nm or less.When the filler is organic fine particles, the average particle size of the organic fine particles is, for example, 10 μm or less, preferably 5 μm or less, and more preferably 0.5 μm or more and 3 μm or less.

[0040] The thickness of the hard coat layer 20 is, for example, 0.5 μm or more and 100 μm or less, and preferably 1 μm or more and 20 μm or less. When the thickness of the hard coat layer 20 is 1 μm or more, scratches are less likely to occur during production. Furthermore, when the thickness of the hard coat layer 20 is 20 μm or less, the optical laminate 100 can be made thinner and lighter. Furthermore, when the thickness of the hard coat layer 20 is 20 μm or less, microcracks in the hard coat layer 20 that occur when the optical laminate 100 is bent during production are less likely to occur, resulting in good productivity.

[0041] <Adhesion layer> The adhesion layer 30 is formed to improve adhesion between the hard coat layer 20, which is an organic film, and the optical function layer 50A, which is an inorganic film. The adhesion layer 30 is preferably made of an oxygen-deficient metal oxide or metal. An oxygen-deficient metal oxide refers to a metal oxide in which the number of oxygen atoms is deficient compared to the stoichiometric composition. Examples of oxygen-deficient metal oxides include SiOx, AlOx, TiOx, ZrOx, CeOx, MgOx, ZnOx, TaOx, SbOx, SnOx, and MnOx. Examples of metals include Si, Al, Ti, Zr, Ce, Mg, Zn, Ta, Sb, Sn, Mn, and In. The adhesion layer 30 may be, for example, SiOx, where x is greater than 0 and less than 2.0. The adhesion layer may also be formed from a mixture of multiple metals or metal oxides.

[0042] The thickness of the adhesive layer 30 is preferably more than 0 nm and not more than 20 nm, particularly preferably 1 nm or more and not more than 10 nm, from the viewpoint of maintaining adhesion between the hard coat layer 20 and the optical functional layer 40 and obtaining good optical properties.

[0043] <Optical functional layer> The optical function layer 40 is formed on the film substrate 10. In this embodiment, "formed on" includes a configuration in which the layer is in direct contact with the film substrate 10 and a configuration in which the layer is formed via another layer. The optical function layer 40 is a layer that exhibits an optical function. The optical function is a function that controls the properties of light, such as reflection, transmission, and refraction, and examples thereof include an anti-reflection function, a selective reflection function, an anti-glare function, and a lens function.

[0044] The optical functional layer 40 is, for example, a laminated film in which high-refractive index layers and low-refractive index layers are alternately stacked in this order from the film substrate 10 side. The high-refractive index layers have a higher refractive index than the low-refractive index layers. The reflection wavelength and reflectance of the optical laminate 100 can be designed, for example, by the optical thicknesses of the high-refractive index layers and low-refractive index layers, the total number of high-refractive index layers and low-refractive index layers, and the refractive index difference between the high-refractive index layers and low-refractive index layers.

[0045] From the viewpoint of flexibility of the optical laminate, the total number of high refractive index layers and low refractive index layers in the optical laminate is preferably 4 or 6. From the viewpoint of flexibility, the thickness of the optical functional layer 40 is preferably a physical thickness of 300 nm or less, more preferably a physical thickness of 290 nm or less.

[0046] In the optical laminate 100, the optical function layer 40 is made up of a first high refractive index layer 41a, a first low refractive index layer 42a, a second high refractive index layer 41b, and a second low refractive index layer 42b. The optical thickness of the first high refractive index layer 41a is 25 nm or more and 43 nm or less, preferably 27 nm or more and 35 nm or less, and more preferably 27 nm or more and 32 nm or less. The optical thickness of the first low refractive index layer 42a is 54 nm or more and 69 nm or less, and preferably 57 nm or more and 67 nm or less. The optical thickness of second high refractive index layer 41b is 276 nm or more and 308 nm or less, preferably 278 nm or more and 293 nm or less, and more preferably 278 nm or more and 283 nm or less. The optical thickness of the second low refractive index layer 42b is 128 nm or more and 141 nm or less, and preferably 129 nm or more and 136 nm or less.

[0047] The refractive index of the high-refractive-index layer is preferably 2.00 or more and 2.60 or less, more preferably 2.10 or more and 2.45 or less. Examples of the main component of such a high-refractive-index layer include niobium pentoxide (Nb2O5, refractive index 2.33), titanium oxide (TiO2, refractive index 2.33 to 2.55), tungsten oxide (WO3, refractive index 2.2), cerium oxide (CeO2, refractive index 2.2), tantalum pentoxide (Ta2O5, refractive index 2.16), zinc oxide (ZnO, refractive index 2.1), indium oxide (InO2), tin oxide (SnO2), aluminum oxide (AlO2), and composite oxides thereof. Examples of composite oxides include indium tin oxide (ITO) and indium zinc oxide (IZO). The main component of the first high-refractive-index layer 41a and the second high-refractive-index layer 41b is preferably niobium pentoxide. In this specification, the term "main component" refers to the component with the highest content, for example, a content of 80% or more.

[0048] The refractive index of the low-refractive-index layer is preferably 1.20 or more and 1.60 or less, more preferably 1.30 or more and 1.50 or less. Examples of the main component of such a low-refractive-index layer include silicon dioxide (SiO2, refractive index 1.46), calcium fluoride (CaF2, refractive index 1.42), and magnesium fluoride (MgF2, refractive index 1.38). The main component of the first low-refractive-index layer 42a and the second low-refractive-index layer 42b is preferably silicon dioxide. Furthermore, when the refractive index of the low-refractive-index layer falls within the above range, other elements may be contained. Specifically, adding about 10% zirconium in elemental ratio can improve chemical resistance. As another example, N2 gas may be introduced during film formation to improve hardness. Furthermore, a metal element such as Al may be added to improve the optical properties.

[0049] The difference in refractive index between the high refractive index layer and the low refractive index layer is preferably 0.40 or more and 1.40 or less, more preferably 0.70 or more and 1.10 or less. Examples of such combinations of high refractive index layer and low refractive index layer include Nb2O5 and SiO2, TiO2 and SiO2, etc.

[0050] In the optical function layer 40, when the first high-refractive index layer 41a is primarily composed of Nb2O5, the physical thickness is preferably 11 nm to 18 nm, more preferably 12 nm to 15 nm, and even more preferably 12 nm to 14 nm. When the first low-refractive index layer 42a is primarily composed of SiO2, the physical thickness is preferably 37 nm to 47 nm, and more preferably 39 nm to 46 nm. When the second high-refractive index layer 41b is primarily composed of Nb2O5, the physical thickness is preferably 118 nm to 132 nm, more preferably 119 nm to 126 nm, and even more preferably 119 nm to 122 nm. When the second low-refractive index layer 42b is primarily composed of SiO2, the physical thickness is preferably 88 nm to 97 nm, and more preferably 87 nm to 93 nm.

[0051] <Anti-fouling layer> The antifouling layer 50 is formed on the outermost surface of the optical function layer 40 and prevents contamination of the optical function layer 40. Furthermore, when the antifouling layer 50 is applied to a touch panel or the like, it suppresses wear of the optical function layer 40 due to its abrasion resistance. The antifouling layer 50 of this embodiment is made of, for example, a vapor-deposited film formed by vapor-depositing an antifouling material. In this embodiment, the antifouling layer 50 is formed by vacuum-depositing a fluorine-based organic compound as the antifouling material on the upper layer when provided on the optical function layer 40, i.e., on one surface of the second low refractive index layer 42b in the optical laminate 100 shown in FIG. 1. In this embodiment, since the antifouling material contains a fluorine-based organic compound, the optical laminate 100 has even better abrasion resistance and alkali resistance.

[0052] A compound comprising a fluorine-modified organic group and a reactive silyl group (e.g., alkoxysilane) is preferably used as the fluorine-based organic compound constituting the antifouling layer 50. Examples of commercially available products include Optool DSX (manufactured by Daikin Corporation) and KY-100 series (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0053] When a compound consisting of a fluorine-modified organic group and a reactive silyl group (e.g., alkoxysilane) is used as the fluorine-based organic compound constituting the antifouling layer 50 and a layer consisting of SiO2 is used as the second low refractive index layer 42b located on the outermost surface of the optical function layer 40 in contact with the antifouling layer 50, a siloxane bond is formed between the silanol group, which is the skeleton of the fluorine-based organic compound, and the SiO2. This results in good adhesion between the optical function layer 40 and the antifouling layer 50, which is preferable.

[0054] The optical thickness of the antifouling layer 50 is, for example, in the range of 1 nm to 20 nm, and preferably in the range of 3 nm to 13 nm. When the optical thickness of the antifouling layer 50 is 1 nm or more, sufficient abrasion resistance can be ensured when the optical laminate 100 is used for touch panels, etc. When the optical thickness of the antifouling layer 50 is 3 nm or more, the liquid resistance and other properties of the optical laminate 100 are improved. When the optical thickness of the antifouling layer 50 is 13 nm or less, the time required for vapor deposition can be shortened, allowing for efficient production.

[0055] The optical laminate 100 according to this embodiment is provided with the optical functional layer 40 as described above, thereby achieving high infrared transmittance. Specifically, the optical laminate 100 has a total transmittance of 86% or more, preferably 88% or more, more preferably 90% or more, and even more preferably 91% or more at a wavelength of 940 nm. The optical laminate 100 has a specular transmittance of 82% or more, preferably 84% or more, at an incident angle of 5° to 40°. The specular transmittance of 83% or more, preferably 85% or more, at an incident angle of 5° to 30° at a wavelength of 940 nm. The optical laminate 100 has a total reflectance of 10% or less, more preferably 8% or less, at a wavelength of 940 nm.

[0056] The optical laminate 100 according to the present embodiment has the above configuration, and thus exhibits excellent flexibility, enabling it to be compatible with foldable displays and rollable displays. In particular, by using Nb2O5 as the main component of the high refractive index layer and SiO2 as the main component of the low refractive index layer, and making the total physical thickness of each layer 300 nm or less, excellent flexibility can be obtained. By making the total physical thickness of each layer 290 nm or less, particularly excellent flexibility can be obtained. Specifically, for the optical laminate 100 according to the present embodiment, it is preferable from the perspective of compatibility with foldable displays and rollable displays that the mandrel diameter at which no crack occurs in the bending test (conforming to JIS K5600-5-1) by the cylindrical mandrel method is 10 mm or less.

[0057] For the optical laminate 100 according to the present embodiment, the visual reflectance Y is 1.0% or less, preferably 0.8% or less, and more preferably 0.6% or less. Furthermore, by using Nb2O5 as the main component of the high refractive index layer and SiO2 as the main component of the low refractive index layer, the optical laminate 100 according to the present embodiment can achieve both high production stability and higher infrared transmittance, and neutralize the color tone of the reflected light.

[0058] For the optical laminate 100 according to the present embodiment, when light with wavelengths from 380 nm to 780 nm is incident by a standard light source D65, the a* value in the CIE-LAB color system of the total reflected light is -4.0 < a* < 4.0, preferably -3.0 < a* < 3.5, more preferably -2.5 < a* < 3.0, and even more preferably -2.2 < a* ≤ 2.8, and the b* value is -15.0 < b* < 0.0, preferably -13.0 < b* < 0.0, and it may also be -12.0 < b* < -5.0 or -11.5 < b* < -7.0.

[0059] In addition, the optical laminate 100 according to the present embodiment can be said to have a good total reflection hue due to having the above configuration. Further, it is preferable that the optical laminate according to the present embodiment is difficult to visually recognize color unevenness even when the viewing angle changes. When light with a wavelength of 380 nm to 780 nm from a standard light source D65 is incident on the surface of the optical laminate 100 according to the present embodiment at an incident angle within the range of 5° or more and 50° or less, the a* value in the CIE-LAB color system of the regular reflection light is preferably -4.0 < a* < 4.0, more preferably -3.0 < a* < 3.8, and even more preferably -2.5 < a* ≤ 3.7, and the b* value is preferably -15.0 < b* < 6.0, more preferably -13.0 < b* < 5.9, and even more preferably -11.0 < b* < 5.9.

[0060] In particular, when light with a wavelength of 380 nm to 780 nm from a standard light source D65 is incident on the optical laminate 100 according to the present embodiment within the range of an incident angle of 30° or more and 40° or less with respect to the surface, the a* value in the CIE-LAB color system of the regular reflection light is preferably -4.0 < a* < 4.0, more preferably -2.5 < a* < 3.6, even more preferably -1.0 < a* ≤ 3.3, and particularly preferably -0.5 < a* ≤ 3.2, and the b* value is preferably -4.0 < b* < 4.0, more preferably -3.9 ≤ b* < 3.5, even more preferably -3.9 ≤ b* < 3.0, and particularly preferably -3.9 ≤ b* < 2.0. The closer the reflected light when light with an incident angle of 30° to 40° with respect to the surface is incident is to being neutral, for example, when a display device provided with the optical laminate 100 is used for an automotive center console, less coloring can be felt when viewed from the driver's seat.

[0061] [Method for manufacturing an optical laminate] Next, taking the method for manufacturing the optical laminate 100 according to the above embodiment as an example, the method for manufacturing the optical laminate according to the present embodiment will be described. In the present embodiment, as an example of the method for manufacturing an optical laminate, the case of manufacturing the optical laminate 100 using the film substrate 10 wound in a roll shape will be described as an example. First, the film substrate 10 wound in a roll shape is unwound.

[0062] (Hard Coat Layer Forming Process) Then, a material containing a material for the hard coat layer 20 is applied onto the film substrate 10 by a known method, and cured by a known method corresponding to the material for the hard coat layer 20. In this way, the hard coat layer 20 is formed on the film substrate 10 (hard coat layer forming step). The material used may contain one or more additives such as a polymerization initiator and a leveling agent, as necessary. As the polymerization initiator, for example, a photopolymerization initiator is used. For example, an ultraviolet-curable resin composition containing metal oxide particles, a urethane (meth)acrylate oligomer, a trifunctional or higher functional (meth)acrylate monomer, a bifunctional (meth)acrylate monomer, and a photopolymerization initiator is uniformly mixed and prepared using a stirrer such as a disper according to a conventional method.

[0063] Next, the ultraviolet-curable resin composition is applied onto the substrate. The application method is not particularly limited, and a known method can be used. Examples of known application methods include microgravure coating, wire bar coating, direct gravure coating, die coating, dipping, spray coating, reverse roll coating, curtain coating, comma coating, knife coating, and spin coating.

[0064] Next, the UV-curable resin composition on the substrate is dried and photocured to form a hard coat layer 20. The drying conditions are not particularly limited, and natural drying or artificial drying, in which the drying humidity and drying time are adjusted, may be used. However, if wind is blown onto the paint surface during drying, it is preferable to avoid wind ripples on the coating surface. This is because wind ripples can deteriorate the coating appearance and cause uneven thickness on the surface. In addition to UV light, energy rays such as gamma rays, alpha rays, and electron beams can also be used as light to cure the UV-curable resin composition.

[0065] Here, it is preferable to etch the surface of the hard coat layer 20 to protrude the metal oxide particles. The method for protruding the metal oxide particles is not particularly limited as long as it can selectively etch the resin of the hard coat layer 20, and for example, glow discharge treatment, plasma treatment, ion etching, alkali treatment, etc. can be used. Among these, glow discharge treatment, which can treat a large area, is preferably used. Thereafter, the film substrate 10 having the hard coat layer 20 formed on its surface is wound into a roll by a known method.

[0066] Next, an adhesion layer forming step is performed to form an adhesion layer 30 on the hard coat layer 20, and an optical function layer forming step is performed to form an optical function layer 40. Thereafter, an antifouling layer forming step is performed to form an antifouling layer 50 on the optical function layer 40. In this embodiment, it is preferable to perform a first surface treatment step to treat the surface of the hard coat layer 20 before the optical function layer forming step, and then perform the adhesion layer forming step and the optical function layer forming step. Furthermore, in this embodiment, it is preferable to perform a second surface treatment step to treat the surface of the optical function layer 40 after the optical function layer forming step, and then perform the antifouling layer forming step.

[0067] (Adhesion layer formation process) An adhesion layer made of an oxygen-deficient metal oxide is formed on the surface of the hard coat layer 20. Sputtering using a target is preferably used as a method for forming the adhesion layer. For example, when forming an SiOx film, it is preferable to use a silicon target and reactive sputtering in a mixed gas atmosphere of oxygen gas and argon gas. Furthermore, the anti-reflection layer formed on the adhesion layer can also be formed by sputtering, thereby improving productivity.

[0068] (Optical functional layer formation process) As will be described in detail later, the optical functional layer is formed by alternately forming high refractive index layers made of a dielectric material and low refractive index layers made of a dielectric material having a refractive index lower than that of the high refractive index layers by sputtering. The optical functional layer can be formed using, for example, a thin film forming apparatus described in JP 2014-034701 A.

[0069] (Anti-fouling layer formation process) The antifouling layer can be formed by a method such as physical vapor deposition, chemical vapor deposition, wet coating, etc., depending on the material to be formed. For example, the antifouling layer can be formed by vacuum-depositing a fluorine-based compound as an antifouling material.

[0070] In the manufacturing method of the optical laminate 100 of this embodiment, it is preferable that the first surface treatment step, the adhesion layer formation step, the optical functional layer formation step, the second surface treatment step, and the antifouling layer formation step are carried out successively while maintaining the optical laminate in the middle of manufacturing under reduced pressure.

[0071] A specific example of a manufacturing apparatus that can be used in the method for manufacturing an optical laminate of this embodiment is a manufacturing apparatus 200 shown in FIG.

[0072] The manufacturing apparatus 200 shown in Figure 2 includes a roll unwinding device 4, a preprocessing device 2A, a thin film forming device 1, a preprocessing device 2B, a vapor deposition device 3, and a roll winding device 5. As shown in Figure 2, these devices 4, 2A, 1, 2B, 3, and 5 are connected in this order. The manufacturing apparatus 200 shown in Figure 2 is a roll-to-roll type manufacturing apparatus that unwinds a substrate from a roll, passes it through connected devices in succession (preprocessing device 2A, thin film forming device 1, preprocessing device 2B, and vapor deposition device 3 in Figure 2), and then winds it up, thereby continuously forming multiple layers on the substrate.

[0073] When the optical laminate 100 is manufactured using a roll-to-roll manufacturing device, the conveying speed (line speed) of the optical laminate 100 during the manufacturing process can be appropriately set. The conveying speed is, for example, preferably 0.5 to 20 m / min, and more preferably 0.5 to 10 m / min.

[0074] <Roll unwinding device> The roll unwinding device 4 shown in Fig. 2 has a chamber 34 the inside of which is kept at a predetermined reduced pressure, one or more vacuum pumps 21 (one in Fig. 2) that exhaust gas from the chamber 34 to create a reduced pressure atmosphere, and an unwinding roll 23 and a guide roll 22 installed in the chamber 34. As shown in Fig. 2, the chamber 34 is connected to the chamber 31 of the thin film forming apparatus 1 via the pretreatment device 2A. The film substrate 10 having the hard coat layer 20 formed on its surface is wound around the unwinding roll 23. The unwinding roll 23 supplies the film substrate 10 having the hard coat layer 20 formed on its surface to the pretreatment device 2A at a predetermined transport speed.

[0075] <Pre-treatment device 2A> The pretreatment device 2A shown in Fig. 2 has a chamber 32, the interior of which is kept at a predetermined reduced pressure, a can roll 26, a plurality of guide rolls 22 (two in Fig. 2), and a plasma discharge device 44. As shown in Fig. 2, the can roll 26, the guide rolls 22, and the plasma discharge device 44 are installed in the chamber 32. As shown in Fig. 2, the chamber 32 is connected to the chamber 31 of the thin film forming device 1.

[0076] The can roll 26 and the guide roll 22 transport the transparent substrate 11 on which the hard coat layer 20 has been formed, which has been sent from the roll unwinding device 4, at a predetermined transport speed, and send the transparent substrate 11 on which the surface of the hard coat layer 20 has been treated to the thin film forming device 1.

[0077] As shown in Fig. 2, the plasma discharge device 44 is disposed opposite the outer peripheral surface of the can roll 26 at a predetermined distance. The plasma discharge device 44 ionizes gas by glow discharge. The gas is preferably inexpensive, inert, and does not affect optical properties, and examples of the gas that can be used include argon gas, oxygen gas, nitrogen gas, and helium gas. In this embodiment, argon gas or oxygen gas is preferably used as the gas.

[0078] <Thin film forming device> The thin film forming apparatus 1 shown in Fig. 2 includes a chamber 31 having a predetermined reduced pressure atmosphere inside, one or more vacuum pumps 21 (two in Fig. 2) that exhaust gas from the chamber 31 to create a reduced pressure atmosphere, a film forming roll 25, a plurality of guide rolls 22 (two in Fig. 2), a plurality of film forming sections (sputtering chambers) 45 (four in the example shown in Fig. 2), and a plurality of optical monitors 81 to 84 (four in the example shown in Fig. 2). As shown in Fig. 2, the film forming roll 25, the guide roll 22, and the film forming section 45 are installed in the chamber 31. As shown in Fig. 2, the chamber 31 is connected to a chamber 32 of a pretreatment device 2B.

[0079] The film forming roll 25 and the guide roll 22 transport the film substrate 10 having the surface-treated hard coat layer 20 formed thereon, sent from the pre-treatment device 2A, at a predetermined transport speed, and supply the film substrate 10 having the adhesion layer 30 and the optical functional layer 40 formed on the hard coat layer 20 to the pre-treatment device 2B.

[0080] In the thin film forming apparatus 1 shown in Figure 2, an adhesion layer 30 is laminated by sputtering on the hard coat layer 20 of the film substrate 10 running on the film forming roll 25, and high refractive index layers (first high refractive index layer 41a, second high refractive index layer 41b, etc.) and low refractive index layers (first low refractive index layer 42a, second low refractive index layer 42b, etc.) are alternately laminated on top of that to form an optical functional layer 40.

[0081] As shown in FIG. 2 , multiple film forming units 45 are disposed facing the outer circumferential surface of the film forming roll 25 at a predetermined distance, surrounding the film forming roll 25. The number of film forming units 45 is determined based on the total number of laminations of the adhesive layer 30 and the high and low refractive index layers constituting the optical functional layer 40. When the total number of laminations of the high and low refractive index layers constituting the adhesive layer 30 and the optical functional layer 40 is large, making it difficult to ensure sufficient distance between adjacent film forming units 45, multiple film forming rolls 25 may be provided in the chamber 31, and a film forming unit 45 may be disposed around each film forming roll 25. When multiple film forming rolls 25 are provided, additional guide rolls 22 may be installed as necessary. Multiple chambers 31 each equipped with a film forming roll 25 and a film forming unit 45 may be connected together. Furthermore, the diameter of the film forming roll 25 may be appropriately changed to facilitate ensuring sufficient distance between adjacent film forming units 45.

[0082] Each film forming unit 45 has a predetermined target (not shown) placed on an electrode (not shown). A voltage is applied to the target using a known structure. In this embodiment, a gas supply unit (not shown) that supplies a predetermined reactive gas and carrier gas to the target at a predetermined flow rate, and a known magnetic field generating source (not shown) that forms a magnetic field on the surface of the target are provided near the target.

[0083] The target material and the type and flow rate of the reactive gas are determined appropriately depending on the composition of the adhesive layer 30, first high-refractive index layer 41a, second high-refractive index layer 41b, first low-refractive index layer 42a, and second low-refractive index layer 42b formed on the film substrate 10 by passing between the film-forming unit 45 and the film-forming roll 25. For example, when forming a layer made of SiO2, Si is used as the target and O2 is used as the reactive gas. For example, when forming a layer made of Nb2O5, Nb is used as the target and O2 is used as the reactive gas. The first low-refractive index layer 42a and the second low-refractive index layer 42b are preferably formed at a vacuum level of less than 0.5 Pa, and the first high-refractive index layer 41a and the second high-refractive index layer 41b are preferably formed at a vacuum level of less than 1.0 Pa. Forming these layers at the above vacuum levels results in a denser optical function layer 40, a lower water vapor permeability, and improved durability.

[0084] In this embodiment, it is preferable to use magnetron sputtering as the sputtering method from the viewpoint of increasing the film formation speed. The sputtering method is not limited to magnetron sputtering, and may be a two-pole sputtering method that uses plasma generated by DC glow discharge or high frequency, or a three-pole sputtering method that adds a hot cathode.

[0085] In the optical functional layer forming section, the target of the film forming section 45 for forming the optical functional layer 40 is preferably positioned perpendicular to the film substrate 10 on which the hard coat layer 20 and adhesive layer 30 are formed. This configuration allows for the formation of a uniform optical functional layer 40 on the adhesive layer 30. If the film substrate 10 on which the hard coat layer 20 and adhesive layer 30 are formed is positioned curved relative to a target having a flat surface, the distance from the target will vary depending on the position on the film on which the thin film is to be formed, which could result in reduced in-plane uniformity of the formed optical functional layer. Poor in-plane uniformity of the optical functional layer 40 is thought to result in in-plane variation in the optical properties of the optical laminate, such as infrared transmittance and hue at varying viewing angles. Therefore, as shown in Figure 2, it is preferable to form the optical functional layer 40 by sputtering perpendicular to the film.

[0086] The thin film forming apparatus 1 includes, for example, an optical monitor 80, which is a measuring unit that measures optical properties after film formation. In a thin film forming apparatus including multiple chambers, the optical monitor 80 is preferably installed in each chamber. The optical monitor 80 may, for example, measure the optical properties of the adhesion layer 30 and the optical functional layer 40 formed on the hard coat layer 20 in the width direction using an optical head that can scan in the width direction. The optical monitor 80 can measure, for example, the peak wavelength of reflectance as an optical property and convert it into optical thickness to obtain the optical thickness distribution in the width direction. This allows the quality of the layers formed by each film forming unit 45 to be confirmed.

[0087] The thin film forming apparatus configured as described above can form a multilayer optical functional layer 40 by forming a thin film on a film unwound from the guide roll 22. The optical monitor 80 measures the optical characteristics of the thin film formed on the film in the width direction, and based on the optical characteristics, the sputtering conditions, such as the flow rate of reactive gas from the gas supply unit in each film forming unit 45 provided in the width direction, are adjusted in real time to form a thin film with a uniform thickness in both the longitudinal and width directions. It should be noted that the present invention is not limited to the above example, and additional film forming units or cathodes may be added, or a planar or rotary cathode system may be used to increase productivity.

[0088] <Pretreatment device> Pretreatment device 2B shown in Fig. 2 has chamber 32, the interior of which is kept at a predetermined reduced pressure, can roll 26, a plurality of guide rolls 22 (two in Fig. 2), and plasma discharge device 44. As shown in Fig. 2, can roll 26, guide roll 22, and plasma discharge device 44 are installed in chamber 32. As shown in Fig. 2, chamber 32 is connected to chamber 33 of vapor deposition device 3.

[0089] The can roll 26 and the guide roll 22 transport the film substrate 10, on which each layer up to the optical functional layer 40 has been formed, sent from the thin film forming device 1, at a predetermined transport speed, and send the film substrate 10, on which the surface of the optical functional layer 40 has been treated, to the vapor deposition device 3. As the plasma discharge device 44, for example, the same one as the pretreatment device 2A can be used.

[0090] <Vapor deposition equipment> The vapor deposition apparatus 3 shown in Fig. 2 includes a chamber 33 the interior of which is maintained at a predetermined reduced pressure, one or more vacuum pumps 21 (one in Fig. 2) that exhaust gas from the chamber 33 to create a reduced pressure atmosphere, multiple guide rolls 22 (four in Fig. 2), a vapor deposition source 43, and a heating device 53. As shown in Fig. 2, the guide rolls 22 and the vapor deposition source 43 are installed in the chamber 33. The chamber 33 is connected to a chamber 35 of the roll winding device 5.

[0091] The vapor deposition source 43 is disposed opposite the film substrate 10, on which the surface of the optical functional layer 40 has been treated, and which is being transported substantially horizontally between two adjacent guide rolls 22. The vapor deposition source 43 supplies evaporated gas made of a material that will become the antifouling layer 50 onto the optical functional layer 40. The orientation of the vapor deposition source 43 can be set as desired. The heating device 53 heats the material that will become the antifouling layer 50 to the vapor pressure temperature. The heating device 53 can be one that uses a resistance heating method, a heater heating method, an induction heating method, an electron beam heating method, or the like. In the resistance heating method, a container that contains the antifouling material that will become the antifouling layer 50 is heated by passing electricity through it as a resistor. In the heater heating method, the container is heated by a heater arranged around the periphery of the container. In the induction heating method, the container or the antifouling material is heated by electromagnetic induction from an externally installed induction coil.

[0092] The vapor deposition device 3 shown in Figure 2 is equipped with a guide plate (not shown) that guides the vapor deposition material evaporated by the vapor deposition source 43 to a predetermined position, a film thickness meter (not shown) that observes the thickness of the antifouling layer 50 formed by vapor deposition, a vacuum pressure meter (not shown) that measures the pressure inside the chamber 33, and a power supply unit (not shown). The guide plate may have any shape as long as it can guide the evaporated deposition material to a desired position. If the guide plate is not necessary, it does not have to be provided. As the vacuum pressure gauge, for example, an ion gauge can be used. The power supply device may be, for example, a high frequency power supply.

[0093] <Roll winding device> The roll winding device 5 shown in Figure 2 has a chamber 35 inside which a predetermined reduced pressure atmosphere is maintained, one or more vacuum pumps 21 (one in Figure 2) that exhaust gas from the chamber 35 to create a reduced pressure atmosphere, and a winding roll 24 and a guide roll 22 installed in the chamber 35. The film substrate 10 (optical laminate 100) having each layer formed on its surface up to the antifouling layer 50 is wound around the winding roll 24. The winding roll 24 and the guide roll 22 wind up the optical laminate 100 at a predetermined winding speed. If necessary, a carrier film may also be used.

[0094] 2 may be equipped with a dry pump, an oil rotary pump, a turbomolecular pump, an oil diffusion pump, a cryopump, a sputter ion pump, a getter pump, etc. The vacuum pump 21 may be selected appropriately or used in combination to create a desired reduced pressure state in each of the chambers 31, 32, 33, 34, and 35.

[0095] The location and number of vacuum pumps 21 installed in the manufacturing apparatus 200 are not particularly limited as long as they can maintain both chamber 31 of thin film forming apparatus 1 and chamber 33 of vapor deposition apparatus 3 at a desired reduced pressure. In the manufacturing apparatus 200 shown in FIG. 2 , the roll unwinding device 4, pretreatment device 2A, thin film forming apparatus 1, pretreatment device 2B, vapor deposition apparatus 3, and roll take-up device 5 are connected. Therefore, vacuum pumps 21 may be installed in each of chambers 31, 32, 33, 34, and 35, or may be installed in only some of chambers 31, 32, 33, 34, and 35, as long as they can maintain both chamber 31 of thin film forming apparatus 1 and chamber 33 of vapor deposition apparatus 3 at a desired reduced pressure.

[0096] By such a method, the optical laminate 100 according to the above embodiment can be manufactured. The optical laminate 100 according to the above embodiment has high infrared transmittance, exhibits hue stability such that color unevenness is not easily visible even when the viewing angle changes, and exhibits high flexibility that makes it applicable to display devices with curved surfaces due to the use of the film substrate 10.

[0097] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various omissions, substitutions, modifications, and alterations are possible within the spirit and scope of the present invention as set forth in the claims. These embodiments and their modifications are also within the scope of the invention and its equivalents as falling within the scope and spirit of the invention.

[0098] For example, the optical laminate according to this embodiment may have a configuration as shown in Fig. 3. Fig. 3 is a cross-sectional view showing an example of the configuration of an optical laminate according to a modified example of Fig. 1. In addition to the configuration of the optical laminate 100 shown in Fig. 1, the optical laminate 101 shown in Fig. 3 includes an adhesive layer 60 and a release layer 70 on the surface of the film substrate 10 opposite to the side on which the optical functional layer 40 is formed.

[0099] The release layer 70 is a layer that protects the adhesive layer 60. The release layer 70 is peeled off at the time of lamination, and the adhesive layer 60 exposed by peeling off the release layer 70 is adhered to the film substrate 10. The release layer 70 is, for example, paper or film coated with a release agent. The thickness of the release layer 70 is, for example, 70 μm or more and 80 μm or less.

[0100] The adhesive layer 60 is a layer that is adhered to the film substrate 10. The adhesive layer 60 includes, for example, an acrylic adhesive, a silicone adhesive, or a urethane adhesive. The thickness of the adhesive layer 60 is, for example, 10 μm or more and 50 μm or less, and preferably 20 μm or more and 30 μm or less.

[0101] FIG. 4 is a schematic diagram showing how the optical laminate of FIG. 3 is bonded to a substrate. As shown in FIG. 4, the optical laminate 101 is bonded to a bonding surface 301 of an object 300 with the release layer 70 peeled off. The object 300 may be a display device. The size of the optical laminate 101 in the in-plane direction is preferably slightly larger than the bonding surface 301 of the object 300 to which it is bonded. If the size of the optical laminate 101 in the in-plane direction is larger than the bonding surface 301 of the object 300, an excess portion of the optical laminate will protrude from the periphery of the object 300. This excess portion is cut off after the optical laminate is bonded. The cutting can be performed, for example, using a cutting tool (not shown) while the optical laminate is bonded to the object 300.

[0102] FIG. 4 shows an example in which the bonding surface 301 of the object 300 is curved, but the bonding surface 301 may be flat. The optical laminate 101 according to this embodiment can be bonded to a curved surface due to the high flexibility provided by the use of the film substrate 10. Furthermore, the optical laminate according to this embodiment does not have an optical functional layer formed on a curved member. Instead, the film substrate 10 on which the hard coat layer 20 and the adhesive layer 30 are formed is flat, and the optical functional layer 40 is formed. This results in high film thickness accuracy and uniform optical properties in the in-plane direction. Furthermore, after fabrication, the optical laminate according to this embodiment can be bonded to devices with a variety of designs, allowing for a high degree of structural freedom. Furthermore, because the optical laminate according to this embodiment has high film thickness accuracy for each layer, even when bonded to a curved surface, it exhibits high infrared transmittance and suppresses changes in hue when the viewing angle is changed.

[0103] [Goods] The article of this embodiment is, for example, a liquid crystal display panel, an organic EL display panel, or the like, in which the above-described optical laminate is provided on the display surface of an image display unit. Furthermore, the article is not limited to image display devices, and may be any article to which an optical laminate can be applied, such as window glass or goggles on which the optical laminate of this embodiment is provided, the light-receiving surface of a solar cell, a smartphone screen or personal computer display, an information input terminal, a tablet terminal, an AR (augmented reality) device, a VR (virtual reality) device, an electronic display board, the surface of a glass table, a gaming machine, a navigation support device for an aircraft or train, a navigation system, an instrument panel, or the surface of an optical sensor. For example, the optical laminate may be attached to the curved surface of an article having a curved surface.

[0104] The upper and / or lower limit values ​​of the numerical ranges described in this specification can be arbitrarily combined to define a preferred range. For example, the upper and lower limit values ​​of the numerical ranges can be arbitrarily combined to define a preferred range, the upper limit values ​​of the numerical ranges can be arbitrarily combined to define a preferred range, and the lower limit values ​​of the numerical ranges can be arbitrarily combined to define a preferred range.

[0105] In addition, although the drawings show only an optical laminate having the hard coat layer 20 and the adhesive layer 30 formed thereon, the present embodiment is not limited to this example, and the hard coat layer 20 and the adhesive layer 30 may be omitted. For example, when an inorganic material such as a glass film is used as the film substrate 10, these layers may be omitted. [Example]

[0106] EXAMPLES Examples of the present invention will be described below. The optical laminates in the following examples are examples of optical laminates that function as anti-reflection films, but the present invention is not limited to these examples.

[0107] [Example 1] In Example 1, an optical laminate was produced, and the luminous reflectance Y, reflection hue, total reflectance and total transmittance of infrared light with a wavelength of 940 nm, and flexibility were evaluated.

[0108] First, a 5-μm-thick hard coat layer consisting of an acrylic resin layer was formed on an 80-μm-thick TAC substrate. The hard coat layer was formed by photopolymerizing a UV-curable resin containing a urethane (meth)acrylate oligomer, a trifunctional or higher (meth)acrylate monomer, a bifunctional (meth)acrylate monomer, and a photopolymerization initiator. Next, a 3-nm-thick adhesion layer consisting of SiOx was formed on the hard coat layer by sputtering.

[0109] Next, using a thin film forming apparatus, an optical functional layer was formed on the adhesive layer by alternately stacking high refractive index layers and low refractive index layers. Here, in the optical laminate of Example 1, the optical functional layer was composed of four layers: a first high refractive index layer, a first low refractive index layer, a second high refractive index layer, and a second low refractive index layer, from the adhesive layer side. Furthermore, an antifouling layer having an optical thickness of 5 nm and made of an alkoxysilane compound having a perfluoropolyether group was formed on the optical functional layer, thereby producing the antireflection film of Example 1. The optical laminate was produced by the above procedure using a roll-to-roll method using a production apparatus such as that shown in FIG. 2.

[0110] [Examples 2 to 4] An optical laminate was produced in the same manner as in Example 1, except that the optical thickness and haze value of each of the high refractive index layers and low refractive index layers constituting the optical functional layer were changed.

[0111] [Comparative Examples 1 to 4] An optical laminate was produced in the same manner as in Example 1, except that the optical thickness of each of the high refractive index layers and the low refractive index layers constituting the optical functional layer was changed. Here, Comparative Examples 2 to 4 have configurations that fall within the scope of disclosure in Japanese Patent No. 7121070.

[0112] <Evaluation> (Infrared transmittance) The spectral transmittance was measured using a spectrophotometer (manufactured by Hitachi High-Tech Science Corporation, product name: UH4150) in the direction in which incident light is transmitted from the film substrate surface of the optical laminate, and the total transmittance at 940 nm was calculated. In addition, the spectrophotometer (manufactured by JASCO Corporation, product name: V-770) was used to measure the regular transmittance at a wavelength of 940 nm for Example 1 and Comparative Example 1 when the incident angle was changed from 5° to 40°. Here, the specular transmittance is the transmittance when only transmitted light (specular transmitted light) coaxial with the incident angle is detected, and the total transmittance is the transmittance when detected as the sum of the specular transmitted light component and the diffuse transmitted light component using an integrating sphere.

[0113] (Total reflectance) The optical laminate was cut into 50 mm square pieces to serve as evaluation samples. The film substrate surface of the evaluation sample was attached to the surface of a black acrylic plate using a transparent acrylic adhesive, eliminating backside reflection and allowing measurement of only the surface reflection. The luminous reflectance Y was measured using a spectrophotometer (Hitachi High-Tech Science Corporation, product name: UH4150) to measure the spectral reflectance of total reflected light (measurement wavelength: 380 nm to 780 nm, incident angle: 8°, 2-degree field of view). The measured spectral reflectance and the relative spectral distribution of CIE standard illuminant D65 (standard illuminant D65) were used to calculate the luminous reflectance Y (tristimulus value Y) of the object color due to reflection in the XYZ color system specified in JIS Z8701. Here, the total reflected light is the sum of the specular reflected light component and the diffuse reflected light component, and is extracted by an integrating sphere in the spectrophotometer. Furthermore, the reflectance at a wavelength of 940 nm was measured using the same test specimen, and the spectral reflectance of total reflected light (measurement wavelength: 940 nm) was measured for the test specimen using a spectrophotometer (manufactured by Hitachi High-Tech Science Corporation, product name: UH4150).

[0114] (reflection hue) The reflection hue of the total reflected light was calculated based on the XYZ color system obtained in the process of calculating the luminous reflectance Y, and the chromaticities a* and b* in the CIE-Lab color system were calculated by conversion using the following formula. The a* and b* values ​​of the specular reflection hue at incident angles (5°, 10°, 20°, 30°, 40°, 50°) were determined using the same test specimen as for the total reflected light. The specular reflectance (measurement wavelength: 380nm to 780nm) of the test specimen was measured using a spectrophotometer (manufactured by JASCO Corporation, product name: V-770) at each incident angle, and the chromaticities (chromanetics indexes) a* and b* in the CIE-Lab color system were then calculated using the same procedure as for the reflection hue of the total reflected light. In the following formula (1), X, Y, and Z are the tristimulus values ​​of the sample in the XYZ color system, and X n , Y n , Z n are the tristimulus values ​​of a perfect diffuse reflecting surface.

[0115]

number

[0116] (Hayes) The haze value of the produced optical laminate was measured using a haze measuring device (manufactured by Nippon Denshoku Industries Co., Ltd., trade name: NDH800SP) according to the method of JIS-K-7136.

[0117] (Flexibility test) A bending test (based on JIS-K5600-5-1) using a cylindrical mandrel method in which a test piece of anti-reflection film is bent with the anti-reflection layer side facing outward was carried out using a mandrel bending tester (manufactured by COTEC).

[0118] Table 1 summarizes the physical thickness and optical thickness of each layer constituting the optical functional layer in the optical laminates of Examples 1 to 4, the thickness of the antifouling layer, and the properties measured by the above-mentioned means. Table 2 also summarizes the physical thickness and optical thickness of each layer constituting the optical functional layer in the optical laminates of Comparative Examples 1 to 4, the thickness of the antifouling layer, and the properties.

[0119] The judgments of "OK" and "NG" in Table 1 and Table 2 are based on the following criteria. Those that are good are judged as "OK", and those that are defective are judged as "NG". · Infrared transmittance at a wavelength of 940 nm: Whether it is 86% or more · Total reflection hue: Whether the chromaticity a* value is -4.0 < a* < 4.0 and the b* value is -15.0 < b* < 0.0 · Color unevenness due to angle change: Whether there is any that does not satisfy -4.0 < a* < 4.0 and -15.0 < b* < 6.0 for the chromaticity a* value of the specular reflection light when light with wavelengths from 380 nm to 780 nm under the standard light source D65 is incident on the surface at an incident angle of 5° to 50° · Flexibility test: Whether cracks occurred with a mandrel diameter larger than 10 mm (OK if no cracks occurred)

[0120]

Table 1

[0121]

Table 2

[0122]

Table 3

[0123] As shown in Tables 1 and 2, the optical laminates of Examples 1 to 4 according to this embodiment had high infrared transmittance (total transmittance at a wavelength of 940 nm of 86% or more), low luminous reflectance of 1% or less, and good total reflection hue. It was confirmed that the change in hue was small even when the viewing angle was changed. On the other hand, it was confirmed that Comparative Example 1, in which the optical thicknesses of the first low refractive index layer, the second high refractive index layer, and the second low refractive index layer were small, had low infrared transmittance. Furthermore, Comparative Examples 2 to 4, in which the optical thickness of the first low refractive index layer was small, had high infrared transmittance but exhibited significant color unevenness when the viewing angle was changed. Furthermore, in Comparative Examples 2, 3, and 4, the color of the reflected light was not neutral. Thus, the comparative examples did not achieve satisfactory results in terms of total reflection hue and suppression of color unevenness when the viewing angle was changed. In the comparative examples, due to the thickness of the first high-refractive index layer, both the a* and b* hues shifted significantly in the positive direction (+) when the angle was changed. Furthermore, due to the thick optical thickness of the first low-refractive index layer, the a* hues shifted in the positive direction (+) when the angle was changed. The difference between the maximum and minimum values ​​of a* at incident angles of 5° to 50° was 4.5 or less in Examples 1 to 4, and 3.0 or less in Examples 1, 3, and 4. Similarly, the difference between the maximum and minimum values ​​of b* at incident angles of 5° to 50° was 16.7 or less in Examples 1 to 4, 15.0 or less in Examples 1, 2, and 4, and 12.5 or less in Examples 1 and 2. Furthermore, as shown in Table 3, it was confirmed that, at least in Example 1, a certain level of transmittance was maintained even when infrared light was incident at an angle. [Explanation of symbols]

[0124] 10: film substrate, 20: hard coat layer, 30: adhesive layer, 40: optical functional layer, 41a: first high refractive index layer, 41b: second high refractive index layer, 42a: first low refractive index layer, 42b: second low refractive index layer, 50: antifouling layer, 100, 101: optical laminate, 300: object, 301: bonding surface

Claims

1. An anti-reflection film comprising a film substrate and an optically functional layer formed on the film substrate, The optical functional layer is, in order from the film substrate side, a first high refractive index layer having an optical thickness of 25 nm or more and 43 nm or less; a first low refractive index layer having an optical thickness of 54 nm or more and 69 nm or less; a second high refractive index layer having an optical thickness of 276 nm or more and 308 nm or less; a second low refractive index layer having an optical thickness of 128 nm or more and 141 nm or less, The transmittance of light at a wavelength of 940 nm is 86% or more, The luminous reflectance Y is 1.0% or less, An optical laminate in which the a* value of total reflected light in the CIE-LAB color system when light having a wavelength of 380 nm to 780 nm by standard light source D65 is incident is -4.0<a*<4.0 and the b* value is -15.0<b*<0.

0.

2. The CIE-LAB color system of specular reflection when light of wavelengths 380 nm to 780 nm from standard light source D65 is incident on a surface at an angle of incidence of 5° to 50°. a* value is −4<0.0 a*<4.0, the b* value is −15.0<b*<6.0; The optical laminate according to claim 1 .

3. The CIE-LAB color system of specular reflection when light of wavelengths 380 nm to 780 nm from standard light source D65 is incident on the surface at an angle of incidence of 30° to 40°. the a* value is −4.0<a*<4.0, the b* value is −4.0<b*<4.0; The optical laminate according to claim 1 .

4. the film substrate is made of an organic material, The optical functional layer further includes a hard coat layer between the film substrate and the optical functional layer, the hard coat layer being in contact with the film substrate, and an adhesive layer being in contact with the hard coat layer and the optical functional layer, The optical laminate according to claim 1 , further comprising an antifouling layer disposed on the second low refractive index layer opposite to the second high refractive index layer.

5. The optical laminate according to claim 4 , wherein the antifouling layer has an optical thickness of 3 nm or more and 13 nm or less.

6. An article comprising the optical laminate according to any one of claims 1 to 5.

7. The article according to claim 6 , wherein the optical laminate is provided on a surface of an image display device.

Images