Optical laminate and method for producing optical laminate

Abstract

To provide a method for manufacturing an optical laminate capable of forming an optical laminate in which an adhesion layer adheres to each of a base material and an optical functional layer without excessively increasing the number of processes and which is excellent in scratch resistance, and to provide an optical laminate excellent in scratch resistance.SOLUTION: A method for producing an optical layered body including, on a substrate, a first metal oxide layer containing a first metal oxide as a main component and a second metal oxide layer containing a second metal oxide as a main component and being in contact with the first metal oxide layer, the method comprising: Wherein the first metal oxide is an oxide in an oxygen-deficient state, and the method includes a first sputtering step of performing sputtering using a target of a first metal on the base material, and a second sputtering step of performing sputtering using a target of a second metal in the same chamber as the first sputtering step, wherein an oxygen concentration in the chamber is 6% or more and 17% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical laminate and a method for producing an optical laminate. [Background technology]

[0002] An optical laminate such as an anti-reflection film is placed on the outermost surface of a display. In recent years, displays equipped with touch panels have become widespread, and the displays are operated by fingers, a stylus pen, or the like.

[0003] Under these circumstances, optical laminates are required to have a resistance to scratches caused by friction during the above-mentioned operations, that is, scratch resistance.

[0004] A known anti-reflection film that exhibits anti-reflection function has an optical function layer in which high refractive index layers made of a high refractive index material and low refractive index layers made of a low refractive index material are alternately laminated by sputtering.

[0005] Known anti-reflection films include a transparent resin substrate having a hard coat layer containing a curable resin and an inorganic or organic filler, and an adhesive layer, also called a primer layer, on the hard coat layer. The adhesive layer is also called a primer layer. This structure is believed to ensure adhesion between the hard coat layer and the alternating laminate.

[0006] For example, Patent Document 1 discloses an antireflection film including a transparent substrate, a hard coat layer, a primer layer, and an antireflection layer. Patent Document 1 also describes that the moisture permeability of the antireflection film is improved by providing a two-layer structure in which the primer layer has a different composition.

[0007] In the antireflection film of Patent Document 1, the first primer layer on the substrate side is formed of any one of materials such as alumina, silica, niobium oxide, and titanium oxide, and the second primer layer on the optical function layer side is formed of a material different from the first primer layer, that is, SiO or a silane coupling agent.

[0008] Furthermore, Patent Document 2 describes an anti-reflection film having a primer layer containing silicon oxide as a main component and having an argon content adjusted to 0.01 to 0.5 atomic %. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-233667 [Patent Document 2] Japanese Patent Application Publication No. 2019-66515 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in the antireflection film of Patent Document 1, the primer layers, which have a two-layer structure, are made of different materials, and therefore a complicated manufacturing method involving many steps is required.

[0011] As described above, anti-reflection films are applied to displays that are operated with fingers, stylus pens, etc., and require scratch resistance, but the anti-reflection film of Patent Document 2 has not been confirmed to have improved scratch resistance.

[0012] The present invention has been made in consideration of the above circumstances, and aims to provide a method for manufacturing an optical laminate that can form an optical laminate with excellent scratch resistance in which an adhesion layer is in close contact with both the substrate and the optical functional layer without excessively increasing the number of steps, and an optical laminate with excellent scratch resistance. [Means for solving the problem]

[0013] In order to solve the above problems, the present invention provides the following means.

[0014] (1) A method for producing an optical laminate according to one aspect of the present invention is a method for producing an optical laminate including, on a substrate, a first metal oxide layer containing a first metal oxide as a main component, and a second metal oxide layer containing a second metal oxide as a main component and in contact with the first metal oxide layer, The first metal oxide is an oxide in an oxygen-deficient state, a first sputtering step of sputtering a first metal target onto the substrate; a second sputtering step in which sputtering is performed using a target of a second metal in the same chamber as the first sputtering step, The oxygen concentration in the chamber is 6% or more and 17% or less.

[0015] (2) In the method for producing an optical laminate described above in (1), the first sputtering step and the second sputtering step may be continuous steps.

[0016] (3) In the method for producing an optical laminate described in (1) or (2) above, the second sputtering step may be reactive sputtering performed in a mixed gas of Ar and O2, and the second sputtering step may be performed under conditions where the flow rate of Ar around the second metal target is 50 sccm or more and 600 sccm or less, and the flow rate of O2 is 25 sccm or more and 85 sccm or less.

[0017] (4) In the method for producing an optical laminate according to any one of (1) to (3), the first metal oxide is represented by the general formula SiO x and the second metal oxide may be Nb2O5.

[0018] (5) In the above methods (1) to (4) for producing an optical laminate, the first sputtering step and the second sputtering step may be carried out in parallel.

[0019] (6) The method for producing the optical laminate of (1) to (5) above may use a first film formation apparatus including the first target and a first gas supply device in the first sputtering step, and supply only argon gas from the first gas supply device in the first sputtering step; and use a second film formation apparatus including the second target and a second gas supply device in the second sputtering step, and supply only argon gas from the second gas supply device in the second sputtering step.

[0020] (7) An optical laminate according to one aspect of the present invention includes a transparent substrate, a first metal oxide layer formed on the transparent substrate, and a second metal oxide layer provided in contact with the first metal oxide layer, the first metal oxide layer comprises an oxide of silicon in an oxygen-deficient state; the second metal oxide layer comprises Nb2O5; In a scratch test based on JIS R3255 with a load increase rate of 1.66 N / s, the peel load is 50 mN or more.

[0021] (8) In an optical laminate according to one embodiment of the present invention, after a pen sliding test using a spherical pen with a tip diameter of 320 μm and a hardness of 120 MPa, the area ratio of the sliding marks in a binarized image analyzed by brightness is 5% or less.

[0022] (9) An optical laminate according to one aspect of the present invention includes a transparent substrate, a first metal oxide layer formed on the transparent substrate, and a second metal oxide layer provided in contact with the first metal oxide layer. the first metal oxide layer comprises an oxide of silicon in an oxygen-deficient state; the second metal oxide layer comprises Nb2O5; The optical laminate is produced by any one of the methods for producing an optical laminate described above in (1) to (6). [Effects of the Invention]

[0023] According to the present invention, it is possible to provide a method for manufacturing an optical laminate that can form an optical laminate with excellent scratch resistance in which an adhesion layer is in close contact with both the substrate and the optical functional layer without excessively increasing the number of steps, and an optical laminate with excellent scratch resistance. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view showing an example of a configuration of an optical laminate according to one embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of a modified example of the optical laminate of FIG. [Figure 3] FIG. 3 is a schematic diagram showing an example of the configuration of a manufacturing apparatus that can be used to manufacture the optical laminate of FIGS. [Figure 4] 4 is a schematic diagram showing an example of a manufacturing apparatus having a different configuration from that shown in FIG. 3 that can be used to manufacture the optical laminate of FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present embodiment will be described in detail below with reference to the drawings as appropriate. The drawings used in the following description may show characteristic portions enlarged for the sake of clarity, 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 thereto. Appropriate modifications can be made within the scope of the present invention. In each drawing, similar components are designated by similar reference numerals, and their description will be omitted.

[0026] [Optical laminate] Fig. 1 is a cross-sectional view of an optical laminate according to one embodiment of the present invention. The optical laminate 10 shown in Fig. 1 includes a transparent substrate 1, an adhesive layer 3, an optical functional layer 4, and an antifouling layer 5. The optical functional layer 4 is formed by alternately stacking high-refractive-index layers 4a and 4c and low-refractive-index layers 4b and 4d. In this embodiment, the adhesive layer 3 is also referred to as a first metal oxide layer, and the high-refractive-index layer 4a is also referred to as a second metal oxide layer.

[0027] (Transparent base material) The transparent substrate 1 is made of a transparent material that can transmit light in the visible light range. The transparent substrate 1 is, for example, a plastic film. Examples of materials that make up the plastic film include polyester resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins.

[0028] The transparent substrate 1 is preferably made of a polyester resin, acetate resin, polycarbonate resin, or polyolefin resin. The transparent substrate 1 is preferably made of, for example, polyethylene terephthalate or triacetyl cellulose (TAC).

[0029] In addition, the "transparent material" in the present invention refers to a material having a transmittance of 80% or more, preferably 90% or more, and more preferably 95% or more, to light in the wavelength range used, within a range that does not impair the effects of the present invention. In addition, in this embodiment, "(meth)acrylic" means methacrylic and acrylic.

[0030] The transparent substrate 1 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.

[0031] The transparent substrate 1 may be a film having optical and / or physical functions. Examples of films having optical and / or physical functions include a polarizing plate, a retardation compensation film, a heat-shielding film, a transparent conductive film, a brightness-enhancing film, and a barrier-enhancing film.

[0032] The thickness of the transparent substrate 1 is not particularly limited, but is preferably in the range of, for example, 20 μm or more and 1000 μm or less. When the thickness of the transparent substrate 1 is 20 μm or more, the rigidity of the substrate itself is ensured, and wrinkles are less likely to occur even when stress is applied to the optical laminate 10A.

[0033] When the optical laminate 10A is produced by roll-to-roll production, if the thickness of the transparent substrate 1 is 1000 μm or less, the optical laminate 10A during production and the optical laminate 10A after production can be easily wound into a roll, and the optical laminate 10A can be produced efficiently. Furthermore, if the thickness of the transparent substrate 1 is 1000 μm or less, the optical laminate 10A can be made thinner and lighter. If the thickness of the transparent substrate 1 is 600 μm or less, the optical laminate 10A can be produced more efficiently and can be made even thinner and lighter, which is preferable.

[0034] The transparent substrate 1 may be a film having optical or physical functions. Examples of substrates having optical or physical functions include polarizing plates, retardation compensation films, heat-shielding films, brightness-improving films, and barrier-improving films.

[0035] The surface of the transparent substrate 1 may be previously subjected to an etching treatment such as sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, conversion, or oxidation, and / or a primer treatment. If necessary, the surface of the transparent substrate 1 may be subjected to solvent washing, ultrasonic washing, or the like to remove dust and clean the surface of the transparent substrate 1.

[0036] (adhesion layer) The adhesion layer 3 is formed on the transparent substrate 1, which is an organic film. In this embodiment, "formed on the transparent substrate 1" includes a form in which the adhesion layer 3 is formed in contact with the transparent substrate 1 and a form in which the adhesion layer 3 is formed on the transparent substrate 1 via another organic film. The adhesion layer 3 is also referred to as a first metal oxide layer.

[0037] The adhesion layer 3 is a layer formed to improve the adhesion between the organic film and the inorganic film. From the viewpoint of maintaining the adhesion between the transparent substrate 1 which is an organic film and the optical functional layer 4 which is an inorganic film and obtaining good optical characteristics, the thickness of the adhesion layer is preferably more than 1 nm and not more than 8 nm, and particularly preferably 3 nm or more and 5 nm or less.

[0038] The adhesion layer 3 preferably contains a metal oxide in an oxygen-deficient state as a main component and has a structure composed of a metal oxide. In the present embodiment, the metal oxide contained as the main component in the adhesion layer 3 is referred to as the first metal oxide. In the present embodiment, the main component means 50% by mass or more, and preferably 90% by mass or more. That is, in the adhesion layer 3, the content of the composition other than the main component is less than 50% by mass, and preferably less than 10% by mass. Examples of the first metal oxide include SiOx, AlOx, TiOx, ZrOx, CeOx, MgOx, ZnOx, TaOx, SbOx, SnOx, MnOx, etc., and it is preferably an oxide of silicon represented by SiOx. In the above formula, x is greater than 0 and less than 2, and is estimated to be a numerical value within a range greater than 1 and less than 1.7.

[0039] The adhesion layer 3 is such a thin layer that when performing ESCA (X-ray photoelectron spectroscopy) used for composition analysis, since it has a thickness smaller than the measurement range, information on the composition of the adjacent layer is included. Therefore, it is currently impossible or not practically feasible to specify the composition of the adhesion layer 3 in the present embodiment (it is considered to be within the range of 1 < x < 2 in the above formula). However, in the first sputtering process described in detail later, when forming the adhesion layer 3, by reducing the amount of oxygen contributing to the reaction, an oxygen-deficient state can be achieved, and an oxide of silicon in an optimal oxygen-deficient state can be formed.

[0040] (Optical functional layer) The optical function layer 4 is a laminate that exhibits an anti-reflection function. The optical function layer 4 shown in Fig. 1 is a laminate of four layers in total, in which high refractive index layers 4a, 4c and low refractive index layers 4b, 4d are alternately laminated in this order from the adhesive layer 3 side. The number of high refractive index layers and low refractive index layers is not particularly limited, and can be any number of layers.

[0041] The optical function layer 4 has a laminated structure in which high refractive index layers 4a, 4c and low refractive index layers 4b, 4d are alternately laminated, so that when light incident from the antifouling layer 5 side is reflected at the interface between the layers, the light cancels out each other due to interference. Therefore, an antireflection function is obtained that prevents light incident from the antifouling layer 5 side from being reflected in one direction.

[0042] In this embodiment, of the high refractive index layers 4a and 4c, the high refractive index layer 4a, which is in contact with the adhesive layer 3, may be referred to as a second metal oxide layer.

[0043] The refractive index of the high refractive index layers 4a and 4c is preferably 2.00 to 2.60, and more preferably 2.10 to 2.45. Examples of dielectric materials that can be used for the high refractive index layers 4a 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 tin oxide (ITO, refractive index 2.06), and zirconium oxide (ZrO2, refractive index 2.2), with niobium pentoxide being preferred.

[0044] The refractive index of the low refractive index layers 4b, 4d is preferably 1.20 to 1.60, more preferably 1.30 to 1.50. Examples of dielectric materials used for the low refractive index layers 4b, 4d include magnesium fluoride (MgF2, refractive index 1.38). The low refractive index layers 4b, 4d contain, for example, a metal oxide. The low refractive index layer 4b may contain an oxide of silicon from the viewpoints of availability and cost, and is preferably a layer whose main component is SiO2 (oxide of silicon) or the like. An SiO2 single-layer film is colorless and transparent. In this embodiment, the main component of the low refractive index layer 4b means a component contained in the low refractive index layer 4b at 50% by mass or more.

[0045] When the low refractive index layers 4b and 4d are layers mainly composed of an oxide of Si, they may contain less than 50 mass% of another element. The content of elements other than the oxide of Si is preferably 10% or less. Examples of other elements that may be included include Na for improving durability, Zr, Al, or N for improving hardness, and Zr and Al for improving alkali resistance.

[0046] In the optical function layer 4, it is preferable that the high refractive index layers 4a and 4c are made of niobium pentoxide (Nb2O5, refractive index 2.33) and the low refractive index layers 4b and 4d are made of SiO2.

[0047] The thickness of the low refractive index layers 4b and 4d may be in the range of 1 nm to 200 nm, and is appropriately selected depending on the wavelength range in which the anti-reflection function is required. The thickness of the high-refractive-index layers 4a and 4c may be, for example, 1 nm or more and 200 nm or less, and may be appropriately selected depending on the wavelength range in which the anti-reflection function is required. The thicknesses of the high-refractive-index layers 4a and 4c may be the same or different. For example, the thickness of the high-refractive-index layer 4a may be greater than that of the high-refractive-index layer 4c. The thicknesses of the high refractive index layers 4 a and 4 c and the low refractive index layers 4 b and 4 d can be appropriately selected depending on the design of the optical function layer 4 . For example, from the adhesive layer 3 side, the layers may be a high refractive index layer 4a of 5 to 50 nm, a low refractive index layer 4b of 10 to 80 nm, a high refractive index layer 4c of 20 to 200 nm, and a low refractive index layer 4d of 50 to 200 nm. The low refractive index layers 4b and 4d may have the same or different thicknesses. For example, the low refractive index layer 4b may have a larger thickness, or the low refractive index layer 4d may have a larger thickness.

[0048] Of the layers constituting the optical functional layer 4, a high refractive index layer is disposed on the adhesive layer 3 side, and a low refractive index layer is disposed on the antifouling layer 5 side.

[0049] (Anti-fouling layer) The antifouling layer 5 is on the outermost surface of the optical functional layer 4. The antifouling layer 5 prevents the optical functional layer 4 from being soiled. Furthermore, when the antifouling layer 5 is applied to a touch panel or the like, it suppresses wear of the optical functional layer 4 due to its abrasion resistance and scratch resistance.

[0050] The antifouling layer 5 is, for example, a vapor-deposited film formed by vapor-depositing an antifouling material. The antifouling layer 5 is formed, for example, by vacuum-depositing a fluorine-based compound as the antifouling material on one surface of the low refractive index layer 4b constituting the optical function layer 4. When the antifouling layer 5 contains a fluorine-based compound, the abrasion resistance and alkali resistance of the optical laminate 10 are further improved.

[0051] The fluorine-based compound contained in the anti-fouling layer 5 is, for example, a fluorine-based organic compound. The fluorine-based organic compound is, for example, a compound comprising a fluorine-modified organic group and a reactive silyl group (e.g., alkoxysilane). Commercially available products that can be used for the anti-fouling layer 5 include Optool DSX (manufactured by Daikin Corporation) and KY-100 series (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0052] When a compound consisting of a fluorine-modified organic group and a reactive silyl group (e.g., alkoxysilane) is used for the antifouling layer 5 and SiO2 is used for the low refractive index layer 4b of the optical function layer 4, a siloxane bond is formed between the silanol group, which is the skeleton of the fluorine-based organic compound, and the SiO2. The siloxane bond improves the adhesion between the optical function layer 4 and the antifouling layer 5.

[0053] The optical thickness of the antifouling layer 5 is, for example, 1 nm or more and 20 nm or less, and preferably 3 nm or more and 10 nm or less. When the thickness of the antifouling layer 5 is 1 nm or more, the optical laminate 10 can be easily touched. Sufficient abrasion resistance can be ensured when the antifouling layer 5 is used for panels, etc. Furthermore, when the thickness of the antifouling layer 5 is 20 nm or less, the time required for vapor deposition is short, allowing for efficient production.

[0054] The antifouling layer 5 may contain additives such as light stabilizers, ultraviolet absorbers, colorants, antistatic agents, lubricants, leveling agents, antifoaming agents, antioxidants, flame retardants, infrared absorbers, and surfactants, as needed.

[0055] In the above embodiment, the optical laminate 10A in which the adhesion layer 3 is formed directly on the transparent substrate 1 has been described, but the present invention is not limited to the above embodiment. For example, the adhesion layer 3 may be formed on the transparent substrate 1 via another layer. Even in this case, the adhesion layer 3 is formed in contact with the organic film. An optical laminate having such a configuration has, for example, a configuration as shown in FIG. 2.

[0056] The optical laminate 10B shown in Fig. 2 includes a hard coat layer 2 between a transparent substrate 1 and an adhesive layer 3. The adhesive layer 3 is provided in contact with the hard coat layer 2. In the optical laminate 10B shown in Fig. 2, the same components as those in the optical laminate 10A are denoted by the same reference numerals, and descriptions thereof will be omitted.

[0057] (Hard coat layer) The hard coat layer 2 is in contact with the transparent substrate 1. When the hard coat layer 2 is formed, the surface of the transparent substrate 1 may be previously subjected to an etching treatment such as sputtering, corona discharge, ultraviolet irradiation, electron beam irradiation, chemical conversion, or oxidation, and / or an undercoating treatment, thereby improving the adhesion of the hard coat layer 2 to be formed on the transparent substrate 1. Furthermore, before forming the hard coat layer 2 on the transparent substrate 1, the surface of the transparent substrate 1 may be subjected to solvent washing, ultrasonic cleaning, or the like, as necessary, to remove dust and clean the surface of the transparent substrate 1.

[0058] Known hard coat layers can be used as the hard coat layer 2, and providing the hard coat layer 2 can improve the mechanical properties of the antireflection film, such as hardness and elastic modulus. The hard coat layer 2 may be made of only a binder resin, or may contain a filler together with the binder resin to the extent that transparency is not impaired. The filler may be made of an organic substance, an inorganic substance, or a mixture of organic and inorganic substances.

[0059] The binder resin used in the hard coat layer 2 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. Examples of the ionizing radiation curable resin used as the binder resin of the hard coat layer 2 include ethyl (meth)acrylate, ethylhexyl (meth)acrylate, styrene, methylstyrene, and N-vinylpyrrolidone. Examples of the compound that is an ionizing radiation curable resin 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 ... Examples of suitable polyfunctional compounds include erythritol 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 particularly preferred. The term "(meth)acrylate" refers to methacrylate and acrylate. Furthermore, 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. Furthermore, oligomers such as urethane acrylate and epoxy acrylate may also be used in combination.

[0060] Examples of thermoplastic resins used as the binder resin of the hard coat layer 2 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 preferably amorphous and soluble in organic solvents (particularly common solvents capable of dissolving multiple polymers and curable compounds). In particular, from the viewpoints of transparency and weather resistance, styrene-based resins, (meth)acrylic resins, alicyclic olefin-based resins, polyester-based resins, cellulose derivatives (cellulose esters, etc.), and the like are preferred.

[0061] Examples of thermosetting resins used as the binder resin of the hard coat layer 2 include phenolic resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, unsaturated polyester resins, polyurethane resins, epoxy resins, aminoalkyd resins, melamine-urea co-condensation resins, silicon resins, and polysiloxane resins (including so-called silsesquioxanes such as cage-shaped and ladder-shaped silsesquioxanes).

[0062] The thickness of the hard coat layer 2 is not particularly limited, but is preferably 0.5 μm or more, and more preferably 1 μm or more. The thickness of the hard coat layer 2 is preferably 100 μm or less. When the thickness of the hard coat layer 2 is 0.5 μm or more, sufficient hardness is obtained, making it less likely to suffer from scratches during production. Furthermore, when the thickness of the hard coat layer 2 is 100 μm or less, the optical laminate can be made thinner and lighter. Furthermore, when the thickness of the hard coat layer 2 is 100 μm or less, microcracks in the hard coat layer 2 that occur when the optical laminate is bent during production are less likely to occur, improving productivity.

[0063] The hard coat layer 2 may be a single layer or a laminate of multiple layers, but is preferably a single layer from the viewpoint of man-hours. The hard coat layer 2 may further be provided with known functions such as ultraviolet absorption performance, refractive index adjustment function, and hardness adjustment function.

[0064] Furthermore, the function to be imparted to the hard coat layer 2 may be imparted to a single hard coat layer, or may be imparted to a plurality of separate layers.

[0065] [Method of manufacturing optical laminate] Next, a method for producing the optical laminate according to the above embodiment will be described. A method for producing an optical laminate according to one embodiment of the present invention is a method for producing an optical laminate comprising, on a substrate 1, a first metal oxide layer 3 containing a first metal oxide as a main component, and a second metal oxide layer 4a containing a second metal oxide as a main component and in contact with the first metal oxide layer 3. The method for producing an optical laminate according to one embodiment of the present invention includes a first sputtering step in which sputtering is performed on the substrate 1 using a target of the first metal, and a second sputtering step in which sputtering is performed using a target of the second metal in the same chamber as the first sputtering step, and the oxygen concentration in the chamber is 6% or more and 17% or less.

[0066] Below, the manufacturing method of the optical laminate according to this embodiment will be explained using the so-called roll-to-roll method as an example, in which an optical laminate is manufactured using a transparent substrate wound into a roll and then wound into a roll, but a batch-type manufacturing method may also be used.

[0067] FIG. 3 shows an example of a manufacturing apparatus that can be used to manufacture the optical laminates 10A and 10B according to the above embodiment, in which multilayer sputtering is performed using a single sputtering apparatus. The manufacturing apparatus 20A includes a roll unwinding / winding apparatus 14A, a vapor deposition apparatus 13, a pretreatment apparatus 12, a sputtering apparatus 11, and a roll unwinding / winding apparatus 14B, which are connected in this order. The manufacturing apparatus 20A unwinds the substrate from the roll, performs a predetermined process, rewinds it each time, unwinds it again, and sends the substrate in the opposite direction to the previous process to perform the next process, repeating this process to manufacture the optical laminate 10. In FIG. 3, the direction in which the film is unwound from the roll unwinding / winding apparatus 14A (forward direction) is indicated by an arrow. However, in the manufacturing method of the optical laminate according to this embodiment, the film is also transported in the opposite direction to the direction indicated by the arrow, i.e., in the direction in which the film is wound by the roll unwinding / winding apparatus 14A.

[0068] The conveying speed (line speed) of the optical laminate 10 during production can be set appropriately, and is preferably, for example, 0.5 to 20 m / min, and more preferably 0.5 to 10 m / min.

[0069] The roll unwinding and winding device 14A has a chamber 34, a vacuum pump 21, an unwinding and winding roll 23, and a guide roll 22. The pressure inside the chamber 34 is reduced by the vacuum pump 21. The vacuum pump 21 is a known pump. When used for unwinding in forming the optical functional layer 4, the unwinding and winding roll 23 initially has the transparent substrate 1 on which the hard coat layer 2 has been formed wound thereon. The unwinding and winding roll 23 supplies the transparent substrate 1 and the transparent substrate 1 on which the hard coat layer 2 has been formed toward the pretreatment device 12 at a predetermined transport speed. When used for winding, the unwinding and winding roll 23 winds up the film or optical laminates 10A, 10B that have been subjected to a predetermined process into a roll shape according to the film transport direction.

[0070] The vapor deposition device 13 has a chamber 33, a vacuum pump 21, guide rolls 22, a vapor deposition source 43, and a heating device 53. The pressure inside the chamber 33 is reduced by the vacuum pump 21. The vapor deposition device 13 vapor-deposits an antifouling layer 5 onto the optical function layer 4 formed on the transported film. The vapor deposition device 13 is switched between use and non-use depending on the process.

[0071] The vapor deposition source 43 is located opposite the film being transported approximately 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 5 onto the optical function layer 4. The orientation of the vapor deposition source 43 can be set as desired.

[0072] The heating device 53 heats the material that will become the stain-resistant layer 5 to a vapor pressure temperature. The heating device 53 uses, for example, a resistance heating method, a heater heating method, an induction heating method, or an electron beam heating method.

[0073] The deposition device 13 includes, for example, a guide plate, a film thickness gauge, a vacuum pressure gauge, and a power supply (not shown). The guide plate guides the evaporated deposition material to a desired position. The film thickness gauge measures the deposited film thickness. The vacuum pressure gauge measures the degree of vacuum within the chamber 33. The vacuum pressure gauge is, for example, an ion gauge. The power supply is, for example, a high-frequency power supply.

[0074] The pre-treatment device 12 has a chamber 32, a can roll 26, a guide roll 22, and a plasma discharge device 42. The can roll 26, the guide roll 22, and the plasma discharge device 42 are installed in the chamber 32. The chamber 32 is connected to the chambers 33 and 34. The pressure inside the chamber 32 is reduced. The pre-treatment device 12 is also switched between use and non-use as needed.

[0075] The plasma discharge device 42 is disposed facing the outer peripheral surface of the can roll 26 at a predetermined distance. The plasma discharge device 42 ionizes gas by glow discharge. The gas may be, for example, argon gas, oxygen gas, nitrogen gas, or helium gas. Argon gas is preferred because it is inexpensive, inert, and does not affect optical properties. The plasma discharge device 42 is, for example, a glow discharge device that ionizes argon gas by high-frequency plasma.

[0076] The plasma discharge device 42 performs a first surface treatment process as a pretreatment for the surface on which the adhesion layer 3 and the optical functional layer 4 are formed. In the first surface treatment process, the can roll 26 and the guide roll 22 are rotated to treat the surface of the hard coat layer 2 at a predetermined conveying speed. The plasma discharge device 42 performs, for example, glow discharge treatment, plasma treatment, ion etching, alkali treatment, etc. Glow discharge treatment is capable of treating large areas. The glow discharge treatment roughens the surface of the hard coat layer 2 at the nano level and removes substances with weak bonding strength that are present on the surface of the hard coat layer 2. As a result, the adhesion between the hard coat layer 2 and the adhesion layer 3 formed on the hard coat layer 2 is improved.

[0077] The pretreatment device 12 can also perform a second surface treatment step as a pretreatment for the surface on which the antifouling layer 5 is to be formed. The surface roughness of the film surface after the second surface treatment step may change. The surface roughness of the surface on which the antifouling layer 5 is to be laminated may be adjusted by changing the conditions of the second surface treatment step.

[0078] After passing through the plasma discharge device 42, the film is transported to the sputtering device 11 or the vapor deposition device 13 depending on the transport direction of the film.

[0079] The sputtering apparatus 11 has a chamber 31, a vacuum pump 21, a film-forming roll 25, a guide roll 22, and film-forming sections 41A to 41D. The film-forming roll 25, the guide roll 22, and the film-forming sections 41A to 41D are installed in the same chamber 31. The chamber 31 is depressurized by the vacuum pump 21. An optical function layer forming process including a first sputtering step and a second sputtering step is performed in the chamber 31 of the sputtering apparatus 11. The sputtering apparatus 11 provided in the manufacturing apparatus 20A shown in FIG. 3 is an example of an apparatus that forms an adhesive layer 3 and an optical function layer 4 having a plurality of high-refractive-index layers 4a, 4c and low-refractive-index layers 4b, 4d within a single chamber 31. However, the method for manufacturing an optical laminate according to this embodiment may use separate sputtering apparatuses, omit winding, and form the above layers one or more at a time.

[0080] The film forming units 41A to 41D are film forming units including sputtering targets 41a to 41d and a gas supply device. FIG. 3 illustrates nozzles 141 and 241 of the gas supply device. Hereinafter, the case where nozzle 141 is a nozzle of a reactive gas supply device and nozzle 241 is a nozzle of a discharge gas supply device will be described, but this example is not limiting. The film forming unit 41A is a target unit used to form the adhesive layer 3 and the low-refractive-index layer 4d. The film forming unit 41B is a target unit used to form the high-refractive-index layer 4a. Similarly, the film forming units 41C and 41D are target units used to form the low-refractive-index layer 4b and the high-refractive-index layer 4c, respectively. The target units can be used individually or in combination to obtain low-refractive-index layers and high-refractive-index layers of desired thicknesses. The gas supply devices provided in the film forming units 41A to 41D each have, for example, one or both of the nozzles 141 and 241, which can be independently controlled. 3 shows an example in which each of the film formation units 41A to 41D is provided with a reactive gas supply nozzle 141 that supplies a reactive gas and a discharge gas supply nozzle 241 that supplies a discharge gas, and each is configured to be able to supply a reactive gas and a discharge gas. In FIG. 3, an example is shown in which each of the film formation units 41A to 41D is provided with a reactive gas supply nozzle 141a that supplies a reactive gas and a discharge gas supply nozzle 241 that supplies a discharge gas. Here, the supply of gas from the reactive gas supply nozzle 141 and the discharge gas supply nozzle 241 can be controlled for each of the film formation units 41A to 41D. For example, in the gas supply device of the film formation unit 41A, it is possible to not supply reactive gas only from the reactive gas supply nozzle 141a, but to supply gas from the reactive gas supply nozzles 141 of the other film formation units 41B to 41D. The arrangement of the reactive gas supply nozzles 141 and discharge gas supply nozzles 241 in each of the film forming sections 41A to 41D is not limited to the example in Figure 3 and can be selected arbitrarily. Reactive gases include oxygen gas, nitrogen gas, and hydrogen gas, and oxygen gas is used in this embodiment. Rare gases on the periodic table are used as discharge gases, but argon is preferred in terms of availability and discharge efficiency.

[0081] The film-forming roll 25 and the guide roll 22 transport the film at a predetermined transport speed. The sputtering device 11 sequentially laminates an adhesive layer 3, high-refractive-index layers 4a and 4c, and low-refractive-index layers 4b and 4d by sputtering onto the transparent substrate 1 traveling on the film-forming roll 25. The optical function layer 4 is formed by alternately laminating the high-refractive-index layers and the low-refractive-index layers.

[0082] The film forming units 41A to 41D are disposed opposite the outer peripheral surface of the film forming roll 25 at a predetermined distance, and a plurality of film forming units 41A to 41D are provided to surround the film forming roll 25. The number of conveyances and the output of the film forming units 41A to 41D are determined according to the desired thicknesses of the adhesive layer 3 and the high refractive index layers 4a, 4c and low refractive index layers 4b, 4d that form the optical function layer 4, while taking into consideration the heat resistance of the transparent substrate 1 and the maximum output value of the film forming units 41A to 41D provided in the sputtering device 11.

[0083] Each of the film forming units 41A to 41D includes, for example, targets 41a to 41d, a voltage applying unit (not shown) to the target, a gas supply unit that supplies reactive gas, discharge gas, etc., and a magnetic field generating source that forms a magnetic field on the target surface. The target differs depending on the film to be formed. For example, SiO x When forming a layer made of silicon oxide such as SiO2, Si is used as the target. When forming a layer made of niobium oxide such as Nb2O5, Nb is used as the target and O2 is used as the reactive gas. The film formation method of the film formation units 41A to 41D is, for example, sputtering, preferably magnetron sputtering. Other methods include a two-pole sputtering method that uses plasma generated by DC glow discharge or high frequency, and a three-pole sputtering method that adds a hot cathode.

[0084] The sputtering apparatus 11 may have an optical monitor that measures the optical properties of each layer after it is deposited. The optical monitor checks the quality of each layer. For example, the optical monitor measures the optical properties of each layer in the width direction using an optical head that can scan in the width direction. The optical monitor can measure the optical thickness distribution of each layer in the width direction, for example, by measuring the peak wavelength of reflectance as the optical property and converting it into optical thickness. By measuring the optical properties using the optical monitor, it is possible to form an adhesion layer 3 and an optical functional layer 4 with optimal optical properties while adjusting the sputtering conditions in real time.

[0085] The roll unwinding / winding device 14B has a chamber 35, a vacuum pump 21, an unwinding / winding roll 24, and a guide roll 22. The pressure inside the chamber 35 is reduced by the vacuum pump 21. The unwinding / winding roll 24 winds up the film or optical laminates 10A, 10B that have completed a predetermined processing stage according to the transport direction. The unwinding / winding roll 24 and the guide roll 22 wind up the optical laminates 10A, 10B at a predetermined winding speed. As with the roll unwinding / winding device 14A, the film that has undergone a predetermined processing can also be unwound in the direction of the sputtering device 35. A carrier film may also be used if necessary.

[0086] In the apparatus shown in FIG. 3, the optical laminates 10A and 10B can be produced by forming each layer in the following procedure, for example.

[0087] (First sputtering step) Among the above sputtering processes, the process of forming the adhesive layer 3, which is a first metal oxide layer, so as to contact the transparent substrate 1 or the hard coat layer 2 is called the first sputtering process. The first sputtering process can be performed in the same chamber 31 as the chamber 31 in which the second sputtering process described below is performed. In the first sputtering process, sputtering is performed using a target 41a of the first metal. That is, SiO xWhen forming the adhesion layer 3 from an oxide of silicon in an oxygen-deficient state, a silicon target is used as the target 41a.

[0088] In the first sputtering step, reactive sputtering is performed under conditions in which, for example, no reactive gas is supplied from the reactive gas supply nozzle 141a and discharge gas supply nozzle 241a of the gas supply device (first gas supply device) of the film formation unit 41A, and only discharge gas is supplied. For example, the first sputtering step is performed while only argon gas is supplied from the first gas supply device. That is, in the first sputtering step, no gas is supplied from the reactive gas supply nozzle 141a of the film formation unit 41A, and argon gas is supplied from the discharge gas supply nozzle 241a. In the first sputtering step, the flow rate of the discharge gas from the discharge gas supply nozzle 241a is set depending on the type and surface roughness of the transparent substrate 1, the distance between the film formation units, and the output and frequency during sputtering. However, a flow rate sufficient to generate a stable discharge is preferable; for example, when Ar gas is used, a flow rate of 15 sccm to 40 sccm is preferable.

[0089] For each gas supply, the flow rate can be set using a flow controller, but the flow rate that can be stably controlled varies depending on the degree of vacuum. -3 ~10 -2The reactive gas flow rate that can be stably supplied relative to the gas pressure (Pa) is several sccm. However, if several sccm of oxygen is supplied as a reactive gas from the reactive gas supply nozzle 141a in the first sputtering step for forming a first metal oxide layer by sputtering, the oxygen supply amount becomes excessive, making it difficult to form a first metal oxide in a predetermined oxygen-deficient state exhibiting the desired properties. However, in this embodiment, oxygen gas is not supplied from the reactive gas supply nozzle 141a of the first gas supply device, but a predetermined amount of oxygen is supplied from one or more gas supply devices in the film formation units other than film formation unit 41A, such as the reactive gas supply nozzle 141b of the second gas supply device in film formation unit 41B in the same chamber 31, thereby maintaining the oxygen concentration in chamber 31 within a predetermined range, thereby forming a first metal oxide in a predetermined oxygen-deficient state exhibiting the desired properties. In this case, from the viewpoint of ease of control, it is preferable to supply oxygen from film formation unit 41B adjacent to film formation unit 41A in order to form a first metal oxide layer with the desired composition.

[0090] The atmosphere in chamber 31 during the first sputtering step preferably consists of oxygen as a reactive gas and argon gas as a discharge gas. When performing the first sputtering step, the oxygen concentration in chamber 31 is 6% or more and 17% or less, preferably 15% or less, and more preferably 12% or less. The concentration of other gases containing argon as a main component in chamber 31 is 83% or more and 94% or less. The sputtering power in the first sputtering step is preferably 0.2 kW or more and 0.6 kW or less.

[0091] (Second sputtering step) In addition, among the above sputtering steps, the step of forming the high refractive index layer 4a, which is a second metal oxide layer, on the adhesion layer 3 is referred to as the second sputtering step. The second sputtering step can be performed in the same chamber 31 as the first sputtering step. In the second sputtering step, sputtering is performed using a target 41b of the second metal. That is, when niobium pentoxide is formed as the high refractive index layer 4a, a niobium target is used as the target 41b.

[0092] In the second sputtering step, reactive sputtering is performed under conditions in which, for example, oxygen gas and discharge gas such as argon are supplied from reactive gas supply nozzle 141b and discharge gas supply nozzle 241b of the gas supply device (second gas supply device) of film formation unit 41B. The second sputtering step is preferably performed consecutively with the first sputtering step, for example, and in parallel with the first sputtering step. In a method for producing an optical laminate in which sputtering using target 41a and sputtering using target 41b are performed in the same chamber 31 as shown in FIG. 3, the second sputtering step is performed while supplying oxygen gas and argon gas, taking into account the oxygen gas concentration in chamber 31 that contributes to the reactive sputtering for forming adhesion layer 3.

[0093] In the second sputtering step, the Ar flow rate and O2 flow rate around target 41b are, for example, 30 sccm to 1000 sccm and 10 sccm to 100 sccm, preferably 50 to 600 sccm and 25 to 85 sccm, and more preferably 200 to 400 sccm and 80 to 85 sccm. In this embodiment, when a target unit including a second gas supply device for forming a second metal oxide layer as shown in FIG. 3 is used, the Ar flow rate and O2 flow rate around target 41b refer to the O2 flow rate and Ar flow rate in the reactive gas supply nozzle 141b and discharge gas supply nozzle 241b of the second gas supply device in the target unit being within the above ranges. The sputtering power in the second sputtering step is preferably, for example, 7 kW to 20 kW.

[0094] Because the target 41b for the second sputtering step is adjacent to the target 41a for the first sputtering step, when the first and second sputtering steps are performed in parallel, oxygen supplied from a gas supply device of another film formation unit, such as the second gas supply device of the film formation unit 41B, flows in to form the adhesion layer 3. Therefore, in the first sputtering step, the first metal oxide can be formed on the substrate without supplying oxygen from the first gas supply device of the film formation unit 41A. Furthermore, by setting the oxygen supply amount from the second gas supply device to a predetermined amount and adjusting the oxygen concentration in the chamber 31, an appropriate amount of oxygen contributing to the reaction can be supplied so that the first metal oxide layer has an appropriate oxygen deficiency state.

[0095] The laminate in which the adhesive layer 3 and the high refractive index layer 4a are formed on the transparent substrate 1 through the first sputtering step and the second sputtering step is subjected to sputtering by the above-described method. By sputtering, a low refractive index layer 4b, a high refractive index layer 4c, and a low refractive index layer 4d having desired thicknesses are formed on the adhesive layer 3 and the high refractive index layer 4a. In an example using the manufacturing apparatus shown in FIG. 3 , the low refractive index layers 4b and 4d and the high refractive index layer 4c are formed, for example, by the following steps, including the steps of forming the adhesive layer 3 and the high refractive index layer 4a. The following example shows an example of a method for producing an optical laminate 10B having a hard coat layer 2. However, when producing an optical laminate 10A without a hard coat layer 2, a transparent substrate 1 without a hard coat layer 2 can be used.

[0096] Step 1: First, a film roll having hard coat layer 2 formed thereon is unwound from unwinding / winding device 14A and passed through vapor deposition device 13 without vapor deposition. Pretreatment device 12 plasma-treats the surface of hard coat layer 2, deposition section 41A deposits adhesion layer 3 (first sputtering step described above), and then deposition section 41B deposits high refractive index layer 4a (second sputtering step described above), after which the film is wound into a roll by unwinding / winding device 14B. The oxygen concentration in chamber 31 in step 1 is between 6% and 17%. Step 2: The film that has been formed up to the high refractive index layer 4a and wound up in step 1 is transported from the unwinding and winding device 14B in the opposite direction to the transport direction in step 1, and a low refractive index layer 4b is formed using target 41c provided in film forming section 41C, and then a high refractive index layer 4c is formed using target 41d provided in film forming section 41B, and the film is wound into a roll by the unwinding and winding device 14A. Step 3: The film on which the high refractive index layer 4c has been formed in step 2 is unwound again from the unwinding / winding device 14A, and the low refractive index layer 4d is formed using the film forming section 41A and the film forming section 41C equipped with Si targets, and then the film is wound into a roll by the unwinding / winding device 14B. Step 4: The film obtained in step 3 is unwound from the unwinding / winding device 14B and passed through without using the film forming section, and the surface of the low refractive index layer 4d is subjected to plasma treatment in the pretreatment device 12, an anti-fouling layer 5 is formed in the vapor deposition device 13, and then the film is wound into a roll by the unwinding / winding device 14A.

[0097] In step 3, two film forming units are used in order to make the thickness of the low refractive index layer 4d greater than the thickness of the low refractive index layer 4b. The number of film forming units to be used and other combinations can be changed as appropriate depending on necessary factors, such as thickness adjustment, for both the high refractive index layer and the low refractive index layer.

[0098] 4 is a schematic diagram showing an example of a manufacturing apparatus with a different configuration from that shown in FIG. 3 that can be used to manufacture the optical laminates 10A and 10B according to the above-described embodiment, and is an example of an apparatus that can perform processes from surface treatment of the transparent substrate or hard coat layer to formation of the antifouling layer all at once. The manufacturing apparatus 20B includes a roll unwinding device 14, a pretreatment device 12A, multiple sputtering devices 11A, 11B, and 11C, a pretreatment device 12B, a vapor deposition device 13, and a roll winding device 15, which are connected in this order. The manufacturing apparatus 20B unwinds the substrate from the roll, passes it through these connected devices in order, and then winds it up, thereby producing the optical laminate 10 using a roll-to-roll method.

[0099] Unless otherwise specified, the configuration and function of each device in the manufacturing apparatus 20B are the same as those assigned the same reference numerals in the manufacturing apparatus 20A shown in Figure 3. When the manufacturing apparatus 20B is used, the optical laminates 10A and 10B can be produced in a consistent process without unwinding and rewinding for each process. The configuration of the pre-processing devices 12A and 12B can be the same as that of the pre-processing device 12.

[0100] In the pretreatment device 12A, the surface of the transparent substrate 1 or the hard coat layer 2 is subjected to plasma treatment.

[0101] The film forming sections of the sputtering devices 11A to 11C are configured as follows, for example. The first and second sputtering steps are performed in sputtering apparatus 11A. In this case, a Si target is used as target 41a in film formation section 41A to form adhesion layer 3, and high refractive index layer 4a is formed in film formation section 41B. In this case, the oxygen concentration in chamber 31A is 6% or more and 17% or less, similar to the apparatus shown in FIG. 3, preferably 15% or less, and more preferably 12% or less. The concentration of other gases containing argon as a main component in chamber 31A is 83% or more and 94% or less.

[0102] In the sputtering apparatus 11B, for example, a low refractive index layer 4b is formed using Si targets as the targets 41a and 41b of the film forming sections 41A and 41B, and a high refractive index layer 4c having a thickness greater than that of the high refractive index layer 4a is formed using Nb targets as the targets 41c and 41d of the film forming sections 41C and 41D.

[0103] In the sputtering apparatus 11C, for example, Si targets are used as targets 41a to 41d of film forming sections 41A to 41D to form, for example, a low refractive index layer 4d thicker than the low refractive index layer 4b.

[0104] Thereafter, the surface of the low refractive index layer 4d is plasma-treated in the pretreatment device 12B, and the antifouling layer 5 is formed using the vapor deposition device 13, after which the film is wound up by the winding device 15.

[0105] In producing an optical laminate using the production apparatus 20B shown in FIG. 4, the concentrations of gas components such as oxygen concentration and argon concentration in the chambers 31B and 31C may be different from those in the chamber 31A.

[0106] Furthermore, the configuration of the target used in each film forming section of the sputtering devices 11A to 11C can be changed as appropriate according to the desired film thickness and the like.

[0107] According to the above embodiment, since the adhesion layer 3 is not made up of multiple different layers, the adhesion layer 3 adheres to each of the transparent substrate 1 or the hard coat layer 2, which are organic films, and the optical functional layer 4 without excessively increasing the number of steps, and a manufacturing method for an optical laminate capable of forming an optical laminate with excellent scratch resistance, and optical laminates 10A and 10B with excellent scratch resistance can be provided.

[0108] Hereinafter, the effect of the optical laminates 10A and 10B according to the above embodiment exhibiting excellent adhesion and scratch resistance will be described with reference to reference examples.

[0109] When the optical functional layer 4 made of a metal oxide is formed directly on the organic transparent substrate 1 or hard coat layer 2 without forming an adhesive layer, the bonding strength between the transparent substrate 1 or hard coat layer 2 and the optical functional layer 4 is weak. To strengthen this, an adhesive layer is provided as an intermediate layer between the transparent substrate 1 / hard coat layer 2 and the optical functional layer 4. When the adhesion layer is an oxide of silicon, it forms SiOx by utilizing oxygen radicals on the substrate surface and in the film-forming environment. Increasing the oxygen content in the adhesion layer increases hardness and stress resistance. However, increasing the oxygen content in the adhesion layer weakens the bond with the organic film. On the other hand, a low oxygen content in the adhesion layer reduces adhesion to the optical functional layer, which is a metal oxide. Since poor adhesion at the interfaces of each layer in the laminate structure makes it impossible to achieve excellent scratch resistance, it is important to improve adhesion on both sides of the adhesion layer, i.e., at the interface between the organic film and the adhesion layer and at the interface between the adhesion layer and the optical functional layer, in order to achieve excellent scratch resistance. Increasing the thickness of the adhesion layer or using multiple layers makes it possible to create a configuration in which the properties of the upper and lower surfaces of the adhesion layer are different, but increasing the thickness of the adhesion layer is undesirable from the perspective of transparency.

[0110] According to this embodiment, by devising the conditions for the first sputtering step and the second sputtering step performed in the same chamber, it is possible to form optical laminates 10A and 10B having a thin adhesive layer 3 that has a high bonding strength with an organic film without containing excessive oxygen, as is the case with structures obtained by sputtering while supplying oxygen from a gas supply device in a conventional film formation unit, and that has good adhesion to the first metal oxide layer due to the sufficient oxygen content. That is, in the optical laminates 10A and 10B, the first metal oxide constituting the adhesive layer 3 is in an oxygen-deficient state suitable for adhesion with the inorganic optical functional layer 4 and the organic film located on the opposite side of the optical functional layer 4. Therefore, the optical laminates 10A and 10B according to this embodiment have excellent scratch resistance.

[0111] The optical laminate according to the above embodiment has a peel load of 50 mN or more, preferably 54 mN or more, in a scratch test in accordance with JIS R3255 at a load increasing rate of 1.66 N / s.

[0112] Regarding the scratch test (pen sliding test), in the analysis results under the conditions described in detail in the Examples below, it is preferable that the area of ​​the sliding marks on the sample is 5% or less, more preferably 4.0% or less, and even more preferably 3.6% or less.

[0113] To summarize the measurement of the area percentage of the pen sliding marks, first, a microscope and accompanying software are used to evaluate the sliding marks after pen sliding, and an image of the sliding area is taken under specified measurement conditions. To compare the strength of the sliding marks, the image is binarized at the location of the pen sliding. Image processing software is used to analyze the image brightness in 1 μm x 1 μm units (pixels). The analysis range is specified as a specified range in the center of the image. An image is output in which pixels whose brightness is above a specified value relative to the background brightness are displayed in red, and pixels below that value are displayed in blue. A pen sliding result is considered good when the number of red pixels is 5% or less of the total image area. The areas where this percentage is displayed in red correspond to the damaged areas.

[0114] The pen sliding test was performed under a load of 250 gf, with 60,000 sliding strokes (30,000 strokes back and forth), a stroke distance of 50 mm, and a stroke speed of two strokes per second (one stroke). The pen tip used for the sliding was a stylus pen tip with a spherical tip diameter of 320 μm and a hardness of 120 MPa.

[0115] Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Example]

[0116] Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0117] [Example 1] First, a roll of resin film was prepared, in which a 10 μm-thick acrylic resin coating (hard coat layer) containing silicon oxide fine particles was formed on an 80 μm-thick transparent substrate (TAC).

[0118] Next, using the apparatus shown in Figure 3 in a roll-to-roll system, a process for forming an optical functional layer was carried out on the transparent substrate on which this hard coat layer had been formed, including a pretreatment process, a first sputtering process, and a second sputtering process, using a sputtering apparatus having four cathodes installed in the same chamber, according to the method described below. The first sputtering process and the second sputtering process were carried out in parallel in the same chamber. That is, while the first sputtering process was carried out to form a first metal oxide layer on the hard coat layer, the second sputtering process was simultaneously carried out on the intermediate molded product on which the first metal oxide layer had already been formed, to form a second metal oxide layer on the first metal oxide layer.

[0119] Each deposition section of the chamber includes a gas supply device that can supply gas. The flow rate of each gas can be adjusted using a mass flow meter installed between the gas supply device and the chamber. The thickness of each layer can be adjusted by adjusting the applied power and gas flow rate during deposition, allowing for highly reproducible deposition at a constant line speed.

[0120] In the process of forming an optical functional layer having the first sputtering process and the second sputtering process, after the transparent substrate is placed in the apparatus, 5 × 10 -4 The chamber was evacuated until the pressure reached 10 Pa or less. The first sputtering step and the second sputtering step (step 1 above) were carried out under the following gas supply conditions and sputtering voltage conditions. The oxygen concentration in the chamber was set to 10%. The oxygen concentration in the chamber was measured using a gas analyzer.

[0121] First sputtering process Target material: Si Oxygen supply from the first gas supply unit: 0 sccm Argon supply from first gas supply unit: 20sccm Sputtering power: 0.2kW Thickness of the first metal oxide layer formed: 3 nm

[0122] Second sputtering process Target material: Nb Oxygen supply from first gas supply unit: 28sccm Argon supply from first gas supply unit: 50sccm Sputtering power: 15.7kW Thickness of the second metal oxide layer formed: 12 nm

[0123] In step 2, the film on which a high refractive index layer (thickness: 12 nm) was formed in step 1 was transported into a chamber, and a low refractive index layer (thickness: 45 nm) and a high refractive index layer (thickness: 25 nm) were formed by sputtering. Next, in step 3, the film on which a low refractive index layer and a high refractive index layer were formed on the high refractive index layer in step 2 was transported into a chamber, and a low refractive index layer (thickness: 100 nm) was formed by sputtering. The optical functional layer formed by the above procedure had a high refractive index layer of niobium pentoxide and a low refractive index layer of silicon dioxide, and was configured so that two high refractive index layers and two low refractive index layers were alternately laminated from the transparent substrate side.

[0124] Next, an anti-fouling layer consisting of an alkoxysilane compound having a perfluoropolyether group (KY-1901, manufactured by Shin-Etsu Chemical Co., Ltd.), which is an organic compound having fluorine, was formed on the optical functional layer by vapor deposition at a pressure of 0.01 Pa or less in the vapor deposition chamber, a vapor deposition temperature of 230°C, and a line speed of 2.0 m / min, to produce an optical laminate.

[0125] [Examples 2 to 5, Comparative Examples 1 to 4] An optical laminate was produced in the same manner as in Example 1, except that the conditions for carrying out the first sputtering step and the second sputtering step, and the oxygen concentration in the chamber accordingly, were changed as shown in Table 1.

[0126] (Pen sliding test) First, the optical laminate was attached to a 1 mm thick glass plate using a transparent adhesive sheet (manufactured by Lintec Corporation) so that the antifouling layer was on the surface. A linear sliding test was then performed using a stylus pen tip (Bamboo Sketch / Bamboo Tip refill (medium type) manufactured by Wacom Corporation, 320 μm spherical tip diameter, 120 MPa hardness). The load was 250 gf, the number of sliding strokes was 60,000 (30,000 back and forth strokes), the stroke distance was 50 mm, and the stroke speed was 2 strokes per second (1 back and forth stroke). The sliding marks were the surface where the outermost layer of the layer-by-layer laminate film 6 had been scraped off, and the scratches were the surface where the alternating functional layer and the adhesive layer had peeled off from the hard coat layer. To evaluate the pen sliding marks, a microscope (Dino-Lite AM4113, manufactured by ANMO Electronics Corporation) and its accompanying software, Dino-Capture, were used to capture images of the sliding area at a magnification of 50x, a light intensity of 128, and a contrast of 16. To compare the strength of the sliding marks, the pen sliding areas in the images were binarized. The image processing software, A-Zo-kun (registered trademark) (Asahi Kasei), was used to analyze the image brightness in 1 μm × 1 μm units (pixels). The analysis range was specified as a 176 × 30 pixel area in the center of the image. Images were output in which pixels with a brightness 1.45 times or more than the background brightness were displayed in red, and pixels with a brightness less than 1.45 times were displayed in blue. The pen sliding results were evaluated as good when the red pixels accounted for 5% or less of the total image area. The areas displayed in red correspond to scratches.

[0127] (Scratch test) The scratch resistance of the optical laminates of Examples 1 to 5 and Comparative Examples 1 to 4 was evaluated by measuring the load at which peeling occurred at the interface between the adhesion layer and the optical functional layer in a scratch test at a load increase rate of 1.66 N / s in accordance with JIS R3255. In the table, "n1," "n2," and "n3" represent the load (peel load, unit: mN) at which peeling occurred when a scratch test was performed on each of three samples under similar conditions, and "ave" represents the average.

[0128] Table 1 summarizes the conditions for producing the optical laminates of Examples 1 to 5 and Comparative Examples 1 to 4, as well as the scratch resistance of the optical laminates evaluated by a pen sliding test and a scratch test.

[0129] [Table 1]

[0130] As shown in Table 1, it was confirmed that in Examples 1 to 5, in which the oxygen concentration in the chamber in the first sputtering step was 6% or more and 17% or less, the pen sliding test was good and the peel load in the scratch test showed good results of 50 mN or more. In contrast, in Comparative Examples 1 and 2, in which the oxygen concentration in the chamber in the first sputtering step was 18% or more, the amount of oxygen supplied when forming the adhesion layer was excessive, resulting in weak bonding with the organic film and a low peel load. On the other hand, in Comparative Examples 3 and 4, in which the oxygen concentration in the chamber in the first sputtering step was 5% or less, the amount of oxygen supplied when forming the adhesion layer was insufficient, resulting in insufficient adhesion at the interface with the high refractive index layer facing the adhesion layer, and scratches were generated in the pen sliding test even after only a few strokes. [Explanation of symbols]

[0131] 10A, 10B: Optical laminate 1: Transparent base material 2: Hard coat layer 3: Adhesion layer (first metal oxide layer) 4: Optical functional layer 4a: High refractive index layer (second metal oxide layer) 4b: Low refractive index layer 4c: High refractive index layer 4d: Low refractive index layer 5: Antifouling layer

Claims

1. A method for producing an optical laminate comprising: a first metal oxide layer containing a first metal oxide as a main component on a substrate; and a second metal oxide layer containing a second metal oxide as a main component and in contact with the first metal oxide layer, the method comprising: The first metal oxide is an oxide in an oxygen-deficient state, a first sputtering step of sputtering a first metal target onto the substrate; a second sputtering step in which sputtering is performed using a target of a second metal in the same chamber as the first sputtering step, The method for producing an optical laminate, wherein the oxygen concentration in the chamber is 6% or more and 17% or less.

2. The method for producing an optical laminate according to claim 1 , wherein the first sputtering step and the second sputtering step are continuous steps.

3. The second sputtering step is performed using Ar and O ２ It is a reactive sputtering method performed in a mixed gas of The second sputtering step is performed by setting the flow rate of Ar around the second metal target to 50 sccm or more and 600 sccm or less, and setting O ２ The method for producing an optical laminate according to claim 1 , wherein the flow rate of the first and second gases is 25 sccm or more and 85 sccm or less.

4. The first metal oxide has the general formula SiO ｘ is an oxide of silicon represented by The second metal oxide is Nb ２ O ５ The method for producing an optical laminate according to claim 1 ,

5. The method for producing an optical laminate according to claim 1 , wherein the first sputtering step and the second sputtering step are carried out in parallel.

6. In the first sputtering step, a first film formation apparatus including a target of the first metal and a first gas supply apparatus is used, In the first sputtering step, only argon gas is supplied from the first gas supply device; In the second sputtering step, a second film forming apparatus including a target of the second metal and a second gas supply apparatus is used, The method for producing an optical laminate according to claim 1 , wherein only argon gas is supplied from the second gas supply device in the second sputtering step.

7. A transparent substrate, a first metal oxide layer formed on the transparent substrate, and a second metal oxide layer provided in contact with the first metal oxide layer. the first metal oxide layer comprises an oxide of silicon in an oxygen-deficient state; The second metal oxide layer is Nb ２ O ５ Including, An optical laminate having a peel load of 50 mN or more in a scratch test in accordance with JIS R3255 at a load increasing rate of 1.66 N / s.

8. 8. The optical laminate according to claim 7, wherein after a pen sliding test using a pen having a spherical tip diameter of 320 μm and a hardness of 120 MPa, the area ratio of the sliding marks in a binarized image analyzed by brightness is 5% or less.

9. A transparent substrate, a first metal oxide layer formed on the transparent substrate, and a second metal oxide layer provided in contact with the first metal oxide layer. the first metal oxide layer comprises an oxide of silicon in an oxygen-deficient state; The second metal oxide layer is Nb ２ O ５ Including, An optical laminate produced by the method for producing an optical laminate according to any one of claims 1 to 6.

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