WO2025177961A1 - Optical laminate, method for producing optical laminate, and article - Google Patents

Abstract

Provided is a method for producing an optical laminate including a substrate, a high-refractive-index layer provided directly or via another layer on the substrate, a low-refractive-index layer formed on the high-refractive-index layer and containing SiO₂ as a main component, and an antifouling layer formed on the low-refractive-index layer, the method comprising: a high-refractive-index layer forming step; a low-refractive-index layer forming step for forming a low-refractive-index layer in a dry atmosphere; a plasma treatment step for performing plasma treatment on the low-refractive-index layer; and an antifouling layer forming step for forming an antifouling layer on the surface, wherein in the plasma processing step, the low-refractive-index layer is subjected to plasma treatment at an electrode power density of 4,400 W/m² to 18,000 W/m² under an environment in which a mixed gas of water vapor and argon gas is introduced. Also provided is an optical laminate in which the binding energy of SiO₂ as measured by X-ray photoelectron spectroscopy (ESCA) from the antifouling layer side is 103.25 eV or less.

Description

Optical laminate, method for producing optical laminate, and article

The present invention relates to an optical laminate, a method for producing an optical laminate, and an article.
This application claims priority based on Japanese Patent Application No. 2024-023257 filed on February 19, 2024, and Japanese Patent Application No. 2025-21608 filed on February 13, 2025, the contents of which are incorporated herein by reference.

Anti-reflective films are used in a variety of devices to prevent surface reflections. For example, they are used in in-vehicle films such as head-up displays, and in smartphone touch panels. Anti-reflective films are typically optical laminates in which a hard coat layer is formed on a transparent substrate, high-refractive index layers and low-refractive index layers are alternately formed on the hard coat layer as optical functional layers, and an anti-fouling layer made of a fluorine compound is formed on the optical functional layer.

As a method for manufacturing an antireflection film made of an optical laminate, for example, a method is known in which a resin solution containing fine particles with different refractive indices is prepared, and layers with different refractive indices are sequentially coated and dried to obtain a laminate (e.g., Patent Document 1). Another method is known in which an optical functional layer is formed on a substrate by sputtering, vapor deposition, or the like, and an antifouling layer is then formed by vapor deposition or the like (e.g., Patent Documents 2, 3, 4, and 5). In Patent Documents 2 and 3, the outermost layer of the optical functional layer farthest from the substrate is a layer containing _SiO2 as a main component, formed as a low refractive index layer, and the low refractive index layer is formed by sputtering, and an antifouling layer composed of a fluorine-based compound is formed on the low refractive index layer by coating or vapor deposition.

Furthermore, Patent Documents 2 and 3 disclose that reactive sputtering using water vapor as a reactive gas is performed when forming the inorganic layer in order to form an optical laminate in which organic layers such as an anti-fouling layer and inorganic layers have high adhesion.

JP 2015-197634 A JP 2012-251193 A JP 2014-43600 A JP 2009-117569 A International Publication No. 2015/097898

Anti-reflective films are expected to be touched by users, and as a result, they may become contaminated with sebum, dust, and other contaminants. Sebum contamination in particular affects visibility. The fluorine-based compounds that make up the anti-fouling layer bond with the substrate that makes up the inorganic layer, and play a role in suppressing such contamination. If dirt does adhere to the surface of an anti-reflective film, it can be maintained by removing it with an alkaline chemical. Head-up displays and smartphone touch panels that use anti-reflective films are used for long periods of time, so they are required to be alkali-resistant for the long term.

Here, when an inorganic layer is formed by sputtering in a water vapor environment as in Patent Documents 1 and 2, it is believed that hydroxyl groups are formed inside the inorganic layer. It is known that inorganic layers composed of oxides such as _SiO2 are dissolved by hydrolysis with _H2O . As the dissolution of the inorganic layer progresses, optical properties such as refractive index may change. Furthermore, the dissolution of the inorganic layer is facilitated by the substitution of alkali metals for H elements in the hydroxyl groups.

The present invention was made in consideration of the above circumstances, and aims to provide an optical laminate that exhibits excellent alkali resistance over the long term, as well as a method for producing such an optical laminate and an article.

The inventors have discovered that by forming hydroxyl groups on the outermost surface of the inorganic layer that bond to the substrate of the inorganic layer, it becomes easier to add the substrate of the antifouling layer, and that if excessive hydroxyl groups are formed even within the inorganic layer, it may not be possible to obtain excellent alkali resistance. In other words, the present invention provides the following means to solve the above problems.

(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 a substrate, a high-refractive index layer provided on the substrate directly or via another layer, a low-refractive index layer formed on the high-refractive index layer and containing _SiO2 as a main component, and an anti-fouling layer formed on the low-refractive index layer, the method including a high-refractive index layer-forming step of forming the high-refractive index layer, a low-refractive index layer-forming step of forming the low-refractive index layer in a dry atmosphere, a plasma treatment step of plasma-treating the low-refractive index layer, and an anti-fouling layer-forming step of forming an anti-fouling layer on the surface, in which the low-refractive index layer is plasma-treated in an environment where a mixed gas of water vapor and argon gas is introduced, at an electrode power density of 4400 W/ ^m2 or more and 18000 W/ ^m2 or less.

(2) In the method for producing an optical laminate described in (1) above, in the plasma treatment step, the flow rate of water vapor in the mixed gas of water vapor and argon gas introduced may be 10% or more and 90% or less.

(3) The electrode power density in the plasma treatment step of (1) or (2) above may be 7000 W/m ² or more and 14000 W/m ² or less.

(4) In the method for producing an optical laminate described in (1) to (3) above, the low refractive index layer may be formed by a sputtering method in the low refractive index layer formation step.

(5) In the method for producing an optical laminate according to any one of (1) to (4) above, in the antifouling layer forming step, the antifouling layer may be formed by a vapor deposition method, and the antifouling layer may contain a compound having an alkoxysilyl group and a fluorine-modified organic group.

(6) In the method for producing an optical laminate according to any one of (1) to (5) above, in the plasma treatment step, the proportion of H ₂ O in the atmosphere in the space where the low refractive index layer is plasma treated may be 6.5% or more and 50% or less.

(7) An optical laminate according to one aspect of the present invention includes a substrate, a high-refractive index layer formed on the substrate directly or via another layer, a low-refractive index layer formed on the high-refractive index layer and containing _SiO2 as a main component, and an antifouling layer formed on the low-refractive index layer, wherein after a 0.1 (mol/L) aqueous NaOH solution is dropped onto the optical laminate and the optical laminate is allowed to stand at 55°C for 4 hours, the ΔE value represented by the following formula (1) is 8 or less.
ΔE ^* _ab = {(L ^* ₂ - L ^* ₁ ) ² + (a ^* ₂ - ^{a *} ₁ ) ² + (b ^* ₂ - b ^* ₁ ) ² } ^1/2 ... (1)
(Wherein, L ^* ₁ : brightness before adding NaOH aq, L ^* ₂ : brightness after a predetermined time has elapsed since adding NaOH aq, a ^* ₁ : chromaticity before adding NaOH aq, a ^* ₂ : chromaticity after leaving the solution for a predetermined time since adding NaOH aq, b ^* ₁ : chromaticity before adding NaOH aq, b ^* ₂ : chromaticity after leaving the solution for a predetermined time since adding NaOH aq).

(8) The optical laminate of (7) above may have a SiO ₂ bond energy of 103.25 eV or less as measured by X-ray photoelectron spectroscopy (ESCA) from the antifouling layer side.

(9) In the optical laminate of (7) and (8),
the high refractive index layer is composed of an oxide of a first metal,
the low refractive index layer is composed of an oxide of a second metal,
The metal elements detected by the ESCA measurement may be only the first metal element and the second metal element.

(10) The optical laminates of (7) and (8) above,
an adhesive layer is further provided between the substrate and the high refractive index layer,
the high refractive index layer is composed of an oxide of a first metal,
the low refractive index layer is composed of an oxide of a second metal,
the adhesion layer is composed of an oxide of a third metal,
The metal elements detected by the ESCA measurement may be only the first metal element, the second metal element, and the third metal element.
(11) An article according to one aspect of the present invention includes the optical laminate of any one of (7) to (9) above.

The present invention provides an optical laminate that exhibits excellent alkali resistance over the long term, as well as a method for producing the optical laminate and an article.

1 is a cross-sectional view showing an example of a configuration of an optical laminate according to one embodiment of the present invention. FIG. 2 is a cross-sectional view of another example of an optical laminate shown in FIG. 1 . 1 is a perspective view showing an example of the configuration of an article to which an optical laminate according to one embodiment of the present invention is applied. 1 is a schematic diagram showing an example of a manufacturing apparatus that can be used in a method for manufacturing an optical laminate according to one embodiment of the present invention. FIG. 5 is a diagram showing an example of a pretreatment device 2B in the manufacturing apparatus shown in FIG. 4.

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.

[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 101 shown in Fig. 1 is formed by sequentially laminating a transparent substrate 11, a hard coat layer 12, an adhesive layer 13, an optical functional layer 14 composed of a high refractive index layer 14a and a low refractive index layer 14b, and an antifouling layer 15. In the optical laminate 101, the high refractive index layer 14a is located closer to the transparent substrate 11, and the low refractive index layer 14b is located farther from the transparent substrate 11 than the high refractive index layer 14a.

Fig. 2 is a cross-sectional view of another example of an optical laminate shown in Fig. 1. The optical laminate 102 shown in Fig. 2 has an optical functional layer 14 in which multiple high-refractive-index layers 14a and low-refractive-index layers 14b are alternately stacked. In the optical laminate 102, the high-refractive-index layer 14a is provided at a position closest to the transparent substrate 11 in the optical functional layer 14, and the low-refractive-index layer 14b is provided at a position farthest from the transparent substrate 11. That is, in both the examples shown in Figs. 1 and 2, the antifouling layer 15 is in contact with the low-refractive-index layer 14b of the optical functional layer 14. The low-refractive-index layer 14b is a layer containing _SiO2 as a main component.

The optical laminate of the present invention comprises a substrate (transparent substrate 11), a high refractive index layer 14a formed on the substrate directly or via another layer, a low refractive index layer 14b formed on the high refractive index layer 14a and containing _SiO2 as a main component, and an antifouling layer 15 formed on the low refractive index layer 14b, and has a ΔE value represented by the following formula (1) of 8 or less after a 0.1 (mol/L) aqueous NaOH solution is added dropwise and allowed to stand at 55°C for 4 hours. The optical properties of the optical laminate, such as lightness and chromaticity, are measured using an integrating sphere spectrocolorimeter, as described below.

ΔE ^* _ab = {(L ^* ₂ - L ^* ₁ ) ² + (a ^* ₂ - ^{a *} ₁ ) ² + (b ^* ₂ - b ^* ₁ ) ² } ^1/2 ... (1)
(Wherein, L ^* ₁ : lightness before adding NaOH aq, L ^* ₂ : lightness after a predetermined time has elapsed since adding NaOH aq, a ^* ₁ : chromaticity before adding NaOH aq, a ^* ₂ : chromaticity after allowing to stand for a predetermined time since adding NaOH aq, b ^* ₁ : chromaticity before adding NaOH aq, b ^* ₂ : chromaticity after allowing to stand for a predetermined time since adding NaOH aq)

In the optical laminate, when the high refractive index layer 14a is formed on the substrate via another layer, for example, a hard coat layer 12 and an adhesive layer 13 are formed between the substrate and the high refractive index layer 14a. The optical laminates 101 and 102 each include, for example, a transparent substrate 11, a hard coat layer 12, an adhesive layer 13, an optically functional layer 14, and an antifouling layer 15. The optical laminate has a _SiO2 binding energy of 103.25 eV or less as measured by X-ray photoelectron spectroscopy (ESCA) from the antifouling layer 15 side.

The transparent substrate 11 may be formed from a transparent material that is capable of transmitting light in the visible light range. For example, a plastic film is preferably used as the transparent substrate 11. Specific examples of materials that can be used to make 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.

The term "transparent material" as used in the present invention refers to a material having a transmittance of 80% or more for light in the wavelength range used, provided that the effect of the present invention is not impaired.
In the present embodiment, "(meth)acrylic" means methacrylic and acrylic.

The transparent substrate 11 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. Specifically, a triacetyl cellulose (TAC) substrate is preferably used as the reinforcing material.
The transparent substrate 11 may also be a glass film, which is an inorganic substrate.

If the plastic film is a TAC substrate, when a hard coat layer 12 is formed on one side of the film, a permeation layer is formed in which some of the components that make up the hard coat layer 12 penetrate. As a result, adhesion between the transparent substrate 11 and the hard coat layer 12 is improved, and the occurrence of interference fringes due to differences in refractive index between the layers can be suppressed.

The transparent substrate 11 may be a film that has been given optical and/or physical functions. Examples of films with optical and/or physical functions include polarizing plates, phase difference compensation films, heat-blocking films, transparent conductive films, brightness-enhancing films, and barrier-enhancing films.

The thickness of the transparent substrate 11 is not particularly limited, but is preferably 25 μm or more, and more preferably 40 μm or more.
When the thickness of the transparent substrate 11 is 25 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 laminates 101, 102. Furthermore, when the thickness of the transparent substrate 11 is 25 μm or more, wrinkles are less likely to occur even when the hard coat layer 12 is continuously formed on the transparent substrate 11, and there are fewer concerns about production, which is preferable. When the thickness of the transparent substrate 11 is 40 μm or more, wrinkles are even less likely to occur, which is preferable.

When manufacturing is carried out using a roll, the thickness of the transparent substrate 11 is preferably 1000 μm or less, and more preferably 600 μm or less. If the thickness of the transparent substrate 11 is 1000 μm or less, it is easy to wind the optical laminates 101, 102 in the middle of manufacturing and the optical laminates 101, 102 after manufacturing into a roll, and the optical laminates 101, 102 can be manufactured efficiently. Furthermore, if the thickness of the transparent substrate 11 is 1000 μm or less, the optical laminates 101, 102 can be made thinner and lighter. If the thickness of the transparent substrate 11 is 600 μm or less, the optical laminates 101, 102 can be manufactured more efficiently and can be made even thinner and lighter, which is preferable.

The surface of the transparent substrate 11 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. By previously performing these treatments, adhesion to the hard coat layer 12 formed on the transparent substrate 11 can be improved. Furthermore, before forming the hard coat layer 12 on the transparent substrate 11, it is also preferable to remove dust and clean the surface of the transparent substrate 11, as necessary, by subjecting the surface of the transparent substrate 11 to solvent washing, ultrasonic cleaning, or the like.

A known material can be used as the hard coat layer 12. The hard coat layer 12 may consist 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.

The binder resin used in the hard coat layer 12 is preferably transparent, and examples of resins that can be used 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 12 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 ... dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,6-hexanediol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol hexa(meth)acrylate 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 preferably used. The term "(meth)acrylate" refers to methacrylate and acrylate. Furthermore, the ionizing radiation curable resin may be a resin obtained by modifying the above-mentioned compounds with PO (propylene oxide), EO (ethylene oxide), CL (caprolactone), or the like.

Examples of thermoplastic resins used as the binder resin of the hard coat layer 12 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 above-mentioned thermoplastic resins are preferably amorphous and soluble in organic solvents (particularly common solvents capable of dissolving multiple polymers and curable compounds). From the standpoints of transparency and weather resistance, styrene-based resins, (meth)acrylic resins, alicyclic olefin-based resins, polyester-based resins, cellulose derivatives (cellulose esters, etc.), etc. are particularly preferred.

Examples of thermosetting resins used as the binder resin for the hard coat layer 12 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 cage-shaped, ladder-shaped, and other so-called silsesquioxanes).

The hard coat layer 12 may contain an organic resin and an inorganic material, or may be an organic-inorganic hybrid material. For example, the hard coat layer 12 may be formed by a sol-gel method. Examples of inorganic materials include silica, alumina, zirconia, and titania. Examples of organic materials include acrylic resin.
The filler contained in the hard coat layer 12 can be selected from various types depending on the application of the optical laminates 101 and 102, from the viewpoints of antiglare properties, adhesion to the optical functional layer 14 described below, and antiblocking properties. Specifically, known fillers such as silica (oxide of Si) particles, alumina (aluminum oxide) particles, and organic fine particles can be used.

The hard coat layer 12 may contain, for example, a binder resin and silica particles and/or alumina particles as a filler. By dispersing silica particles and/or alumina particles as a filler in the hard coat layer 12, fine irregularities can be formed on the surface of the hard coat layer 12. These silica particles and/or alumina particles may be exposed on the surface of the hard coat layer 12 facing the optical function layer 14. In this case, the binder resin of the hard coat layer 12 and the optical function layer 14 are strongly bonded. This improves adhesion between the hard coat layer 12 and the optical function layer 14, increases the hardness of the hard coat layer 12, and improves the scratch resistance of the optical laminates 101, 102.

The average particle size of the silica particles and/or alumina particles used as filler in the hard coat layer 12 is, for example, 800 nm or less, preferably 780 nm or less, and more preferably 100 nm or less.

In order to improve the anti-glare properties of the optical laminates 101 and 102, organic fine particles can be used as the filler contained in the hard coat layer 12. Examples of organic fine particles include acrylic resins. The particle diameter of the organic fine particles is preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 3 μm or less. In order to impart toughness to the hard coat layer 12, various reinforcing materials can be used as the filler contained in the hard coat layer 12, as long as the optical properties are not impaired. Examples of reinforcing materials include cellulose nanofibers.

The thickness of the hard coat layer 12 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 12 is preferably 100 μm or less. When the thickness of the hard coat layer 12 is 0.5 μm or more, sufficient hardness is obtained, making it less likely to suffer from scratches during manufacturing. Furthermore, when the thickness of the hard coat layer 12 is 100 μm or less, the optical laminates 101, 102 can be made thinner and lighter. Furthermore, when the thickness of the hard coat layer 12 is 100 μm or less, microcracks in the hard coat layer 12 that occur when the optical laminates 101, 102 are bent during manufacturing are less likely to occur, improving productivity.

The hard coat layer 12 may be a single layer or a laminate of multiple layers. The hard coat layer 12 may further be provided with known functions such as ultraviolet absorption, antistatic properties, refractive index adjustment, and hardness adjustment.
The function to be imparted to the hard coat layer 12 may be imparted to a single hard coat layer, or may be imparted to a plurality of separate layers.

The adhesion layer 13 is a layer formed to improve adhesion between the transparent substrate 11 or hard coat layer 12, which is an organic film, and the optical function layer 14, which is an inorganic film. In the optical laminates 101 and 102 shown in Figures 1 and 2, the adhesion layer 13 is provided between the hard coat layer 12 and the optical function layer 14. The adhesion layer 13 functions to adhere the hard coat layer 12 and the optical function layer 14. The adhesion layer 13 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. In this embodiment, the above metal elements constituting the adhesion layer 13 and the metal elements in the metal oxides may be referred to as third metal elements. The adhesion layer 13 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.

The thickness of the adhesion layer 13 is preferably greater than 0 nm and less than 20 nm, and particularly preferably greater than 1 nm and less than 10 nm, from the viewpoint of maintaining adhesion between the substrate and the optical function layer 14 and obtaining good optical properties.

The optical function layer 14 is a laminate that exhibits anti-reflection properties. The optical function layer 14 is formed by alternately laminating high refractive index layers 14a and low refractive index layers 14b, starting from the transparent substrate 11 side. In the example shown in Figure 1, it consists of a total of two layers, and in the example shown in Figure 2, it consists of a total of four layers. There are no particular limitations on the number of high refractive index layers 14a and low refractive index layers 14b, and any number of layers can be used.

The optical function layer 14 is made up of a laminate of alternating low refractive index layers 14b and high refractive index layers 14a. Light incident from the anti-fouling layer 15 side interferes with the optical function layer 14, reducing the intensity of the reflected light and providing an anti-reflection function. This provides an anti-reflection function that prevents light incident from the anti-fouling layer 15 side from being reflected in one direction.

The low-refractive-index layer 14b is a layer whose main component is, for example, _SiO2 (oxide of silicon). A single _SiO2 layer is colorless and transparent. In this embodiment, the main component of the low-refractive-index layer 14b means a component that is contained in the low-refractive-index layer 14b at 50 mass% or more.

When the low refractive index layer 14b is a layer whose main component is an oxide of Si, it may contain less than 50 mass% of another element, or may be composed of an oxide of Si. In this embodiment, silicon, which is the metal element of the metal oxide contained as the main component in the low refractive index layer 14b, may be referred to as a second metal 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 to improve durability, Zr, Al, or N to improve hardness, and Zr and Al to improve alkali resistance.

The refractive index of the high-refractive-index layer 14a 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 layer 14a include niobium pentoxide (Nb ₂ O ₅ , refractive index 2.33), titanium oxide (TiO ₂ , refractive index 2.33 to 2.55), tungsten oxide (WO ₃ , refractive index 2.2), cerium oxide (CeO ₂ , refractive index 2.2), tantalum pentoxide (Ta ₂ O ₅ , refractive index 2.16), zinc oxide (ZnO, refractive index 2.1), indium tin oxide (ITO, refractive index 2.06), and zirconium oxide (ZrO ₂ , refractive index 2.2). In this embodiment, the metal element of the metal oxide contained as the main component of the high-refractive-index layer, such as niobium, titanium, tungsten, cerium, tantalum, zinc, or zirconium, may be referred to as a first metal element.
If it is desired to impart conductive properties to the high refractive index layer 14a, for example, ITO or indium zinc oxide (IZO) can be selected.

The optical function layer 14 preferably uses, for example, niobium pentoxide (Nb ₂ O ₅ , refractive index 2.33) as the high refractive index layer 14a and SiO ₂ as the low refractive index layer 14b.

The thickness of the low refractive index layer 14b 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 layer 14a may be, for example, 1 nm or more and 200 nm or less, and is appropriately selected depending on the wavelength range in which the anti-reflection function is required.
The thicknesses of the high refractive index layer 14 a and the low refractive index layer 14 b can be appropriately selected depending on the design of the optical function layer 14 .
In the optical laminate 102, for example, the high refractive index layer 14a having a thickness of 5 to 50 nm, the low refractive index layer 14b having a thickness of 10 to 80 nm, the high refractive index layer 14a having a thickness of 20 to 200 nm, and the low refractive index layer 14b having a thickness of 50 to 200 nm can be configured in this order from the adhesive layer 13 side. In the optical laminate 101, the thicknesses of the high refractive index layer 14a and the low refractive index layer 14b can also be selected to be any thickness.

Among the layers forming the optical functional layer 14, a low refractive index layer 14b is disposed on the side closest to the antifouling layer 15. That is, the high refractive index layers 14a and low refractive index layers 14b are alternately disposed so that the layer in contact with the antifouling layer 15 is the low refractive index layer 14b. When the low refractive index layer 14b of the optical functional layer 14 is in contact with the antifouling layer 15, the anti-reflection performance of the optical functional layer 14 is better than when the high refractive index layer 14a is in contact with the antifouling layer 15. Furthermore, as will be described in detail below, in the optical laminates 101 and 102, the Si element located on the outermost surface of the low refractive index layer 14b facing the antifouling layer 15 is bonded to the fluorine organic compound contained in the antifouling layer 15 via an oxygen atom.

The antifouling layer 15 is formed on the outermost surface of the optical function layer 14 and prevents the optical function layer 14 from being soiled or damaged. Furthermore, when the antifouling layer 15 is applied to a touch panel or the like, it suppresses wear of the optical function layer 14 due to its abrasion resistance.
The antifouling layer 15 of this embodiment is made of a vapor-deposited film formed by vapor-depositing an antifouling material. In this embodiment, the antifouling layer 15 is formed by vacuum-depositing a fluorine-based organic compound as the antifouling material on one surface of the low refractive index layer 14b that constitutes the optical function layer 14. In this embodiment, the antifouling material contains a fluorine-based organic compound, which results in the optical laminates 101, 102 having even better abrasion resistance and alkali resistance.

The fluorine-based organic compound that constitutes the anti-fouling layer 15 is preferably a compound consisting of a fluorine-modified organic group and a reactive silyl group (e.g., alkoxysilane). The anti-fouling layer 15 preferably contains a compound having an alkoxysilyl group and a fluorine-modified organic group such as a perfluoropolyether group or a fluoroalkyl group. Commercially available products include Optool DSX (manufactured by Daikin Corporation) and the KY-100 series (manufactured by Shin-Etsu Chemical Co., Ltd.).

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 15 and a layer consisting of SiO2 is used as the low refractive index layer 14b of the optical function layer 14 in contact with the antifouling layer ₁₅ , a siloxane bond is formed between a silanol group generated from the reactive silyl group of the fluorine-based organic compound and a hydroxy group present on the surface of _SiO2 . This results in good adhesion between the optical function layer 14 and the antifouling layer 15, which is preferable.

The optical thickness of the anti-fouling layer 15 may be in the range of 1 nm or more and 20 nm or less, and is preferably in the range of 3 nm or more and 10 nm or less. If the thickness of the anti-fouling layer 15 is 1 nm or more, sufficient abrasion resistance can be ensured when the optical laminates 101, 102 are used for touch panels, etc. Furthermore, if the thickness of the anti-fouling layer 15 is 3 nm or more, the liquid resistance, etc. of the optical laminates 101, 102 is improved. Furthermore, if the thickness of the anti-fouling layer 15 is 20 nm or less, the time required for vapor deposition can be shortened, allowing for efficient production.

In the optical laminates 101 and 102 configured as described above, the bond energy of _SiO2 measured by X-ray photoelectron spectroscopy (ESCA) from the antifouling layer 15 side of the optical laminates 101 and 102 is, for example, 103.25 eV or less. The bond energy is, for example, 103.00 eV or more, and more preferably 103.01 eV or more and 103.15 eV or less. The bond energy of _SiO2 is generally known to be 103.6 eV, and in the optical laminates 101 and 102, it is a value lower than this value.

Furthermore, it is desirable that the alkali resistance be improved by such a wide scan measured by X-ray photoelectron spectroscopy (ESCA) from the antifouling layer 15 side of the optical laminates 101, 102 that no metal elements other than the metals constituting the metal oxides used in the optical laminates are detected. That is, when the high-refractive index layer 14a is composed of an oxide of a first metal and the low-refractive index layer 14b is composed of an oxide of a second metal different from the first metal, it is preferable that only the first and second metal elements are detected by ESCA. When the optical laminate further includes an adhesive layer 13 and the adhesive layer is composed of an oxide of a third metal, it is preferable that only the first, second, and third metal elements are detected by ESCA. For example, in an optical laminate in which the adhesive layer is SiOx, the high-refractive index layer is _{a Nb2O5} film, and the low-refractive index layer is a _SiO2 film, it is preferable that no metal elements other than Si and Nb are detected. Metal elements that can be mixed into such an optical laminate, other than the metals that make up the metal oxides used in the optical laminate, are mainly metals used in electrodes for plasma processing, such as Al, Zr, and Ti.

In the optical laminates 101 and 102, as will be described in detail later, after the low refractive index layer 14b is formed, the low refractive index layer is plasma-treated in an environment where water vapor and argon gas are introduced, that is, in an environment where H ₂ O and Ar are present, whereby some of the siloxane bonds between Si and O located on the outermost surface of the SiO ₂ constituting the low refractive index layer 14b are broken, and react with H ₂ O in the atmosphere during the plasma treatment to generate hydroxy groups bonded to Si, which then bond to the fluorine-based organic compound constituting the antifouling layer 15.

Optical laminates 101 and 102 exhibit high long-term alkali resistance. Specifically, after dropping 0.1 (mol/L) aqueous NaOH solution onto the laminate and leaving it at 55°C for 4 hours, the ΔE value (see formula (1) below) is 8 or less, and preferably 4 or less. If there is no change from before the dropping of the aqueous NaOH solution until 4 hours later, the ΔE value is 0. The ΔE value of optical laminates 101 and 102 is 0 or more, and may be 0.5 or more.

ΔE ^* _ab = {(L ^* ₂ - L ^* ₁ ) ² + (a ^* ₂ - ^{a *} ₁ ) ² + (b ^* ₂ - b ^* ₁ ) ² } ^1/2 ... (1)
(In formula (1), L ^* ₁ is the brightness before the addition of NaOH aq, L ^* ₂ is the brightness after a predetermined time has elapsed since the addition of NaOH aq, a ^* ₁ is the chromaticity before the addition of NaOH aq, a ^* ₂ is the chromaticity after the predetermined time has elapsed since the addition of NaOH aq, b ^* ₁ is the chromaticity before the addition of NaOH aq, and b ^* ₂ is the chromaticity after the predetermined time has elapsed since the addition of NaOH aq.)

[Goods]
FIG. 3 is a perspective view showing an example of the configuration of an article to which an optical laminate according to one embodiment of the present invention is applied. The optical laminates 101 and 102 of this embodiment are provided on the display surface of an image display unit of an article such as a liquid crystal display panel or an organic EL display panel. While FIG. 3 shows an example in which the optical laminate 101 is provided on a main portion 202 surrounded by a frame 201 of an article 200, an article having an optical laminate 102 may also be provided. 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 goggles having the optical laminate of this embodiment provided on its surface, 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, an amusement 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. Preferably, the article according to this embodiment has an optical laminate provided on the surface of a touch panel. The main portion 202 of the article 200 is typically a display portion corresponding to the screen in an article having a screen, and is, for example, a light-transmitting portion that transmits light in an article without a screen. The article according to the present embodiment has such a configuration, and can exhibit long-term durability even when maintenance is performed in which acidic dirt such as sebum is removed with an alkaline chemical or the like.

[Method of manufacturing optical laminate]
The optical laminates 101 and 102 of this embodiment shown in FIGS. 1 and 2 can be produced, for example, by the following method.
In this embodiment, as an example of a method for manufacturing the optical laminates 101 and 102, a case in which the optical laminates 101 and 102 are manufactured using a transparent substrate 11 wound in a roll shape will be described.
First, the transparent substrate 11 wound in a roll shape is unwound. Then, a slurry containing a material for the hard coat layer 12 is applied onto the transparent substrate 11 by a known method, and cured by a known method corresponding to the material for the hard coat layer 12. In this way, the hard coat layer 12 is formed (hard coat layer forming step). Thereafter, the transparent substrate 11 with the hard coat layer 12 formed on its surface is wound into a roll by a known method.

Next, an adhesion layer forming process is performed on the hard coat layer 12, forming an adhesion layer 13, and an optical function layer forming process is performed to form an optical function layer 14. The optical function layer forming process includes a high refractive index layer forming process in which a high refractive index layer 14a is formed and a low refractive index layer forming process in which a low refractive index layer 14b is formed in a dry atmosphere. In this embodiment, a dry atmosphere means that the atmosphere is not humid, and that water vapor is not allowed to flow. Subsequently, a plasma treatment process is performed on the low refractive index layer 14b, and an antifouling layer forming process is performed to form an antifouling layer 15 on the surface. In the plasma treatment process, the low refractive index layer 14b is plasma-treated in an environment where a mixed gas of water vapor and argon gas is introduced. That is, the plasma treatment process is performed in an atmosphere where _H2O and Ar are present. The flow rate of water vapor in the mixed gas of water vapor and argon gas introduced in the plasma treatment process can be, for example, 2% or more and 100% or less, and preferably 10% or more and 90% or less. Here, the flow rate ratio of _H2O in the mixed gas in the plasma treatment step means the ratio of the flow rate of _H2O (the value obtained by subtracting the argon gas flow rate from the total flow rate) (sccm) to the total flow rate (sccm) of gases flowed as reactive gases in the plasma treatment.

The electrode power density in the plasma treatment step is preferably 1400 W/m ² or more and 44200 W/m ² or less, for example, 4400 W/m ² or more and 18000 W/m ² or less, or 7000 W/m ² or more and 14000 W/m ² or less.

In the low refractive index layer formation process, the low refractive index layer is formed using the sputtering method.

In the anti-fouling layer formation process, the anti-fouling layer 15 is formed by vapor deposition. The anti-fouling layer 15 preferably contains a compound having an alkoxysilyl group and a fluorine-modified organic group such as a perfluoropolyether group or a fluoroalkyl group. In this embodiment, prior to the optical function layer formation process, it is preferable to perform a surface treatment process to treat the surface of the hard coat layer 12, and then perform the adhesion layer formation process and the optical function layer formation process.

An example of a manufacturing apparatus that can be used in the method for manufacturing an optical laminate of this embodiment is a manufacturing apparatus 20 shown in FIG.
The manufacturing apparatus 20 is a roll-to-roll type manufacturing apparatus that unwinds the substrate from a roll, passes it through connected devices in succession (pretreatment device 2A, sputtering device 1, pretreatment device 2B, and vapor deposition device 3 in FIG. 4 ), and then winds it up, thereby continuously forming multiple layers on the substrate.

When manufacturing the optical laminates 101, 102 using a roll-to-roll manufacturing device, the conveying speed (line speed) of the optical laminates 101, 102 during manufacturing can be set as appropriate. The conveying speed is preferably, for example, 0.5 to 20 m/min, and more preferably 0.5 to 10 m/min.

<Roll unwinding device>
The roll unwinding device 4 has a chamber 34 the inside of which is kept at a predetermined reduced pressure, one or more vacuum pumps 21 (one in FIG. 4 ) 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. 4 , the chamber 34 is connected to the chamber 31 of the sputtering device 1.
The transparent substrate 11 having the hard coat layer 12 formed on the surface thereof is wound around the unwinding roll 23. The unwinding roll 23 supplies the transparent substrate 11 having the hard coat layer 12 formed on the surface thereof to the pretreatment device 2A at a predetermined transport speed.

<Pretreatment device 2A>
The pretreatment device 2A has a chamber 32, the interior of which is kept under a predetermined reduced pressure, a can roll 26, a plurality of guide rolls 22 (two in FIG. 4 ), and a plasma discharge device 42. As shown in FIG. 4 , the can roll 26, the guide rolls 22, and the plasma discharge device 42 are installed in the chamber 32. As shown in FIG. 4 , the chamber 32 is connected to the chamber 31 of the sputtering device 1.

The can roll 26 and the guide roll 22 transport the transparent substrate 11 on which the hard coat layer 12 has been formed, which has been sent from the roll unwinding device 4, at a predetermined transport speed, and send the transparent substrate 11 with the surface of the hard coat layer 12 treated to the sputtering device 1.
As shown in Figure 4, 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 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. Argon gas is preferably used as the gas because it has a large mass, is chemically stable, and is easily available.
In this embodiment, it is preferable to use a glow discharge device as the plasma discharge device 42, which ionizes argon gas with high frequency plasma.

<Sputtering equipment>
The sputtering apparatus 1 has a chamber 31 inside which a predetermined reduced pressure atmosphere is maintained, one or more vacuum pumps 21 (two in FIG. 4 ) that exhaust gas from the chamber 31 to create a reduced pressure atmosphere, a film-forming roll 25, a plurality of (two in FIG. 4 ) guide rolls 22, and a plurality of (four in the example shown in FIG. 4 ) film-forming units 41. As shown in FIG. 4 , the film-forming roll 25, the guide roll 22, and the film-forming units 41 are installed in the chamber 31. As shown in FIG. 4 , the chamber 31 is connected to a chamber 32 of the pretreatment device 2B.

The film-forming roll 25 and the guide roll 22 transport the transparent substrate 11 having the surface-treated hard coat layer 12 formed thereon, sent from the pre-treatment device 2A, at a predetermined transport speed, and supply the transparent substrate 11 having the adhesion layer 13 and the optical function layer 14 formed on the hard coat layer 12 to the pre-treatment device 2B.
In the sputtering apparatus 1 shown in FIG. 4, an adhesion layer 13 is laminated by sputtering on the hard coat layer 12 of the transparent substrate 11 running on the film-forming roll 25, and high refractive index layers 14 a and low refractive index layers 14 b are alternately laminated on top of the adhesion layer 13 to form an optical function layer 14.

The film forming units 41 are arranged facing the outer peripheral surface of the film forming roll 25 at a predetermined distance, and multiple film forming units 41 are provided to surround the film forming roll 25. The number of film forming units 41 is determined based on the total number of laminated layers of the adhesive layer 13 and the high refractive index layers 14a and low refractive index layers 14b that form the optical functional layer 14. If the total number of laminated layers of the adhesive layer 13 and the high refractive index layers 14a and low refractive index layers 14b that form the optical functional layer 14 is large and it is difficult to ensure sufficient distance between adjacent film forming units 41, multiple film forming rolls 25 may be provided in the chamber 31, and film forming units 41 may be arranged 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 film forming rolls 25 and film forming units 41 may be connected. Furthermore, the diameter of the film forming rolls 25 may be appropriately changed to make it easier to ensure sufficient distance between adjacent film forming units 41.

Each film forming unit 41 is equipped with a predetermined target (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.

The target material and the type and flow rate of the reactive gas are appropriately determined depending on the compositions of the adhesion layer 13, high refractive index layer 14a, and low refractive index layer 14b formed on the transparent substrate 11 by passing between the film-forming unit 41 and the film-forming roll 25. For example, to form the low refractive index layer 14b as a layer containing _SiO2 as a main component, Si is used as the target and _O2 is used as the reactive gas. Also, for example, to form the high refractive index layer _14a containing _Nb2O5 as a main component, Nb is used as the target and _O2 is used as the reactive gas.

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.

The sputtering apparatus 1 is equipped with an optical monitor (not shown) as a measurement unit that measures the optical properties after depositing the layers that will become the adhesion layer 13 and the optical functional layer 14. This makes it possible to confirm the quality of the adhesion layer 13 and the optical functional layer 14 that have been formed. If the sputtering apparatus 1 has, for example, two or more chambers, it is preferable to install an optical monitor in each chamber.

An example of an optical monitor (not shown) is one that uses an optical head capable of scanning in the width direction to measure the optical characteristics in the width direction of the adhesion layer 13 and the optical functional layer 14 formed on the hard coat layer 12. When such an optical monitor is provided, the optical thickness distribution in the width direction of the adhesion layer 13 and the optical functional layer 14 can be measured, for example, by measuring the peak wavelength of reflectance as the optical characteristic and converting it into optical thickness. By measuring the optical characteristics using the optical monitor, it is possible to form optical laminates 101, 102 that include an adhesion layer 13 and an optical functional layer 14 with optimal optical characteristics while adjusting the sputtering conditions in real time.

<Pretreatment device 2B>
Pretreatment device 2B has a chamber 32, the interior of which is maintained at a predetermined reduced pressure, a can roll 26, a plurality of guide rolls 22 (two in FIG. 4 ), and a plasma discharge device 44. As shown in FIG. 4 , can roll 26, guide roll 22, and plasma discharge device 44 are installed in chamber 36. Pretreatment device 2B is connected to a mixed gas adjustment unit 60 that introduces a mixed gas into chamber 36. As shown in FIG. 4 , chamber 36 is connected to chamber 33 of deposition device 3.

The can roll 26 and the guide roll 22 transport the transparent substrate 11, on which each layer up to the optical functional layer 14 has been formed, sent from the sputtering device 1, at a predetermined transport speed, and send the transparent substrate 11, on which the surface of the optical functional layer 14 has been treated, to the vapor deposition device 3.
The plasma discharge device 44 may be, for example, the same as the pretreatment device 2A.

As shown in Figure 4, the plasma discharge device 44 is disposed facing the outer circumferential surface of the can roll 26 at a predetermined distance. The plasma discharge device 44 ionizes gas by glow discharge. The gas may be water vapor or argon gas, and may also be mixed with oxygen gas, nitrogen gas, helium gas, or the like. That is, a mixed gas containing _H2O and argon gas can be introduced from the mixed gas adjustment unit 60 into the chamber 36 in which the plasma discharge device 44 is installed.
In this embodiment, it is preferable to use a glow discharge device as the plasma discharge device 44, which ionizes argon gas with high frequency plasma.

The electrode power density in the plasma treatment step is 1400 W/m ² or more and 44200 W/m ² or less, for example, 4400 W/m ² or more and 18000 W/m ² or less, and more preferably 7000 W/m ² or more and 14000 W/m ² or less.

Figure 5 is a diagram showing an example of the pretreatment device 2B in the manufacturing apparatus shown in Figure 4. Figure 5 shows an enlarged view of an example of the mixed gas adjustment unit 60 shown in a simplified form in Figure 4. The mixed gas adjustment unit 60 includes, for example, an argon gas supply source 61, a water vapor supply source 62 containing water, a heater 63 for heating the water vapor supply source 62, an adjustment chamber 65 connected to the argon gas supply source 61 and the water vapor supply source 62, a vacuum pump 64 for evacuating gas from the adjustment chamber 65, and an H ₂ O thermometer 66 arranged to be able to measure the temperature of the water in the water vapor supply source 62. The component designated by the symbol NB in Figure 5 represents a needle valve, and the component designated by the symbol MFC represents a mass flow controller.

Into the adjustment chamber 65, argon gas, the flow rate of which is measured by a mass flow controller (MFC1), and water vapor contained in a water vapor supply source 62 are supplied from an argon gas supply source, and evaporated water vapor is heated by a heater 63. A mixed gas of argon gas and water vapor, the flow rate of which is adjusted by a mass flow controller (MFC2) installed between the adjustment chamber 65 and the chamber 36, is supplied, and any gas in the adjustment chamber 65 that is not supplied to the chamber 36 is exhausted by a vacuum pump 64.

It is known that argon gas is introduced into chamber 36 from adjustment chamber 65 with priority over water vapor. The proportion of each gas composition in chamber 36 can be measured using a partial pressure vacuum gauge (not shown) installed inside chamber 36. The flow rate of water vapor relative to the total of argon gas and water vapor (total mixed gas) supplied into chamber 36 is thought to depend on the absolute value of the argon gas flow rate. By previously experimenting with the dependence of the flow rate of water vapor relative to the total mixed gas on the flow rate of argon gas, it is possible to adjust the flow rate of argon gas to achieve the desired flow rate of water vapor relative to the total mixed gas supplied into chamber 36.

<Vapor deposition equipment>
The vapor deposition device 3 includes a chamber 33 having a predetermined reduced pressure atmosphere inside, one or more vacuum pumps 21 (one in FIG. 4 ) that exhaust gas from the chamber 33 to create a reduced pressure atmosphere, a plurality of guide rolls 22 (four in FIG. 4 ), a vapor deposition source 43, and a heating device 53. As shown in FIG. 4 , 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.

The vapor deposition source 43 is disposed opposite the transparent substrate 11, the transparent substrate 11 having the treated surface of the optical function layer 14, which is 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 15 onto the optical function layer 14. 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 15 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 15 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.

The vapor deposition device 3 includes 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 gauge (not shown) that observes the thickness of the antifouling layer 15 formed by vapor deposition, a vacuum pressure gauge (not shown) that measures the pressure inside the chamber 33, and a power supply (not shown). The guide plate may have any shape as long as it can guide the evaporated vapor 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.

<Roll winding device>
The roll winding device 5 has a chamber 35 inside which a predetermined reduced pressure atmosphere is maintained, one or more vacuum pumps 21 (one in FIG. 4 ) that exhaust gas from the chamber 35 to create a reduced pressure atmosphere, and a winding roll 24 and a guide roll 22 installed inside the chamber 35.
The transparent substrate 11 (optical laminates 101, 102) having each layer formed on the surface thereof up to the antifouling layer 15 is wound around the winding roll 24. The winding roll 24 and the guide roll 22 wind up the optical laminates 101, 102 at a predetermined winding speed.
If necessary, a carrier film may also be used.

The vacuum pump 21 provided in the manufacturing apparatus 20 may be, for example, a dry pump, oil rotary pump, turbomolecular pump, oil diffusion pump, cryopump, sputter ion pump, or getter pump. The vacuum pump 21 can be selected appropriately or used in combination to create the desired reduced pressure state in each of the chambers 31, 32, 33, 34, and 35.

The vacuum pump 21 is only required to maintain both the chamber 31 of the sputtering apparatus 1 and the chamber 33 of the vapor deposition apparatus 3 at the desired reduced pressure, and the installation position and number of vacuum pumps 21 in the manufacturing apparatus 20 are not particularly limited. Furthermore, in the manufacturing apparatus 20 shown in FIG. 4, the roll unwinding device 4, pre-processing device 2A, sputtering apparatus 1, pre-processing device 2B, vapor deposition apparatus 3, and roll winding device 5 are connected. Therefore, the vacuum pump 21 may be installed in each of the chambers 31, 32, 33, 34, and 35, or may be installed in only some of the chambers 31, 32, 33, 34, and 35, as long as the vacuum pump 21 can maintain both the chamber 31 of the sputtering apparatus 1 and the chamber 33 of the vapor deposition apparatus 3 at the desired reduced pressure.

Next, we will explain a method for manufacturing optical laminates 101, 102 using a roll-to-roll process by performing a high refractive index layer formation process, a low refractive index layer formation process, a plasma treatment process, and an anti-fouling layer formation process on a substrate using the manufacturing apparatus 20 shown in Figure 4.

First, the unwinding roll 23 around which the transparent substrate 11 with the hard coat layer 12 formed on its surface is placed in the chamber 34 of the roll unwinding device 4. Then, the unwinding roll 23 and guide roll 22 are rotated, and the transparent substrate 11 with the hard coat layer 12 formed on its surface is sent to the pre-processing device 2A at a predetermined transport speed.

Next, in the chamber 32 of the pretreatment device 2A, a surface treatment step is performed as a pretreatment for the surface on which the adhesion layer 13 and the optical functional layer 14 are to be formed. In this embodiment, the surface treatment step is performed on the transparent substrate 11 on which the hard coat layer 12 is formed.
In the surface treatment process, the can roll 26 and the guide roll 22 are rotated to transport the transparent substrate 11 on which the hard coat layer 12 is formed at a predetermined transport speed, while treating the surface of the hard coat layer 12 running on the can roll 26.

Examples of methods that can be used to treat the surface of the hard coat layer 12 include glow discharge treatment, plasma treatment, ion etching, and alkali treatment. Among these, glow discharge treatment is preferred because it allows for large-area treatment. The glow discharge treatment can be performed at a treatment intensity of, for example, 0.1 to 10 kWh.
By performing glow discharge treatment on the surface of the hard coat layer 12, the surface of the hard coat layer 12 is roughened at the nano level and substances with weak bonding strength present on the surface of the hard coat layer 12 are removed, resulting in good adhesion between the hard coat layer 12 and the optical function layer 14 formed on the hard coat layer 12.

Next, the adhesion layer forming process and the optical function layer forming process are carried out in the chamber 31 of the sputtering device 1. Specifically, the film-forming roll 25 and the guide roll 22 are rotated, and the transparent substrate 11 on which the hard coat layer 12 has been formed is transported at a predetermined transport speed, while the adhesion layer 13 and the optical function layer 14 are formed on the hard coat layer 12 running on the film-forming roll 25.

Next, the adhesion layer forming process and the optical function layer forming process are carried out in the chamber 31 of the sputtering device 1. The adhesion layer forming process and the optical function layer forming process are carried out, for example, by rotating the film forming roll 25 and the guide roll 22 and transporting the transparent substrate 11 on which the hard coat layer 12 has been formed at a predetermined transport speed.

In this embodiment, first, the adhesion layer 13 is formed by sputtering while changing the target material installed in each film formation unit 41 or the type and flow rate of the reactive gas supplied from the gas supply unit. Then, in the high-refractive-index layer formation process and low-refractive-index layer formation process, high-refractive-index layers 14a and low-refractive-index layers 14b are alternately laminated on the substrate. In the high-refractive-index layer formation process, a high-refractive-index layer is formed on the substrate directly or via another layer. Here, in this embodiment, "on the substrate" means on the transparent substrate 11, and does not necessarily have to be in direct contact with the transparent substrate 11. In this embodiment, the high-refractive-index layer 14a and low-refractive-index layer 14b are formed on the transparent substrate 11 via the hard coat layer 12 and adhesion layer 13.

When depositing an SiOx film as the adhesion layer 13, a silicon target is used and oxygen gas and argon are introduced. When the adhesion layer 13, high refractive index layer 14a, and low refractive index layer 14b are successively laminated by sputtering, the target material may be deposited when depositing the high refractive index layer 14a and the low refractive index layer 14b during deposition of the adhesion layer 13. Alternatively, for example, one type of material may be used as the target, and by changing the oxygen (reactive gas) flow rate during sputtering, layers composed of the target material and layers composed of an oxide of the target material may be alternately formed to form the adhesion layer 13, high refractive index layer 14a, and low refractive index layer 14b.

The low refractive index layer formation process is performed in a dry atmosphere without introducing _H2O into the chamber 31. If _H2O is introduced during the low refractive index layer formation process, _SiO2 inside the optical functional layer that constitutes the low refractive index layer will dissolve due to hydrolysis, forming SiOH, which may cause the properties of the optical laminate to deviate from the intended properties. When siloxane bonds inside the optical functional layer are broken and hydroxy groups are generated, the bond energy of _SiO2 in the optical laminate decreases. Since hydroxy groups bonded to internal Si elements rather than on the surface of the optical functional layer are thought not to be replaced with silane coupling agents, hydroxy groups bonded to internal Si elements away from the surface of the low refractive index layer do not contribute to improving the alkali resistance of the optical laminate even after the antifouling layer formation process.

The sputtering pressure when forming the adhesion layer 13 and the optical function layer 14 may be 2 Pa or less, preferably 1 Pa or less, more preferably 0.6 Pa or less, and particularly preferably 0.2 Pa or less. When the sputtering pressure is reduced to 1 Pa or less, the mean free path of the film-forming molecules becomes longer, and the film-forming molecules are deposited while maintaining high energy, resulting in a denser, better-quality film.

Thereafter, the transparent substrate 11 having the adhesion layer 13 and the optical functional layer 14 formed on the hard coat layer 12 is sent to the pretreatment device 2B by the rotation of the film-forming roll 25 and the guide roll 22. In the pretreatment device 2B, a plasma treatment step is performed. In the plasma treatment step, the low refractive index layer 14b is plasma-treated in an environment where a mixed gas of water vapor and argon gas is introduced. That is, the plasma treatment step is performed in an atmosphere where H ₂ O and Ar are present as reactive gases. The mixed gas introduced in the plasma treatment step is preferably composed only of water vapor and argon gas. The atmosphere in the chamber 32 of the pretreatment device 2B where the plasma treatment step is performed is preferably an atmosphere consisting of water vapor and argon gas.

In the pretreatment device 2B, a pretreatment is performed on the low refractive index layer 14b located on the outermost surface of the optical laminate before the formation of the antifouling layer 15. The pretreatment is a plasma treatment of the surface of the low refractive index layer 14b in an atmosphere containing water vapor and argon gas. Specifically, a glow discharge treatment is performed using a plasma discharge device 44 to ionize one or both of Ar gas and _H2O gas by high-frequency plasma.

As described above, the atmosphere within chamber 36 is one in which water vapor and argon gas are present. While other gases such as oxygen, nitrogen, and helium can be mixed in, an atmosphere consisting solely of water vapor and argon gas is preferred. Water vapor and argon gas can be introduced into chamber 36, for example, by the mixed gas adjustment unit 60. In the mixed gas adjustment unit 60, the mixed gas that has passed through the mass flow controller (MFC2) and needle valve (NB) from the adjustment chamber 65 is introduced into chamber 36. As described above, argon gas, the flow rate of which is measured by the mass flow controller (MFC1) from the argon gas supply source 61, and water vapor from the water vapor supply source 62 are supplied to the adjustment chamber 65. It has been confirmed that, of the mixed gases introduced from the adjustment chamber 65 into chamber 36, argon gas is introduced preferentially over water vapor. Therefore, the flow rate ratio (target %) of water vapor in the mixed gas supplied into chamber 36 can be calculated based on an approximation curve of the dependency of the flow rate ratio of water vapor in the total flow rate of argon gas and water vapor supplied into chamber 36 on the flow rate of argon gas supplied into chamber 36, which has been confirmed in advance through experiments.

The water vapor flow rate (target %) in the mixed gas introduced into the chamber 36 can be, for example, 2% to 100% inclusive, and preferably 10% to 90% inclusive. By performing the plasma treatment process under these conditions, the surface of the low refractive index layer 14b in the optical laminate becomes hydrophilic. This makes it easier for the fluorine-based organic compound that constitutes the anti-fouling layer to bond with the hydroxyl groups generated in the low refractive index layer 14b in the anti-fouling layer formation process described below. This makes it possible to increase the amount of fluorine-based organic compound that constitutes the anti-fouling layer on the outermost surface of the optical laminates 101 and 102. If the moisture content of the atmosphere in the chamber 36 is excessive, some of the hydroxyl groups will not bond with the fluorine-based organic compound and will remain on the surface. When the optical laminate is exposed to an alkaline solution or atmosphere, alkali metals may replace H on the surface, leading to deterioration due to the alkaline solution or atmosphere. Due to this mechanism, it is believed that long-term alkali resistance is particularly high when the moisture content of the atmosphere in the plasma treatment process is below a specified value.

In addition, in the pretreatment device 2B shown in Figures 4 and 5, the argon gas and water vapor in the mixed gas are first stored in the adjustment chamber 65 and then supplied into the chamber 36, so the ratio of water vapor to the total amount of argon gas and water vapor in the atmosphere within the chamber 36 does not necessarily match the flow rate ratio of water vapor in the mixed gas. The ratio (actual ratio) of water vapor to the total amount of water vapor and argon gas in the atmosphere present within the chamber 36 is, for example, more than 0.5% and less than 70%, preferably 6% to 65%, and more preferably 6.5% to 50%.

The total pressure inside the chamber during the plasma treatment process is preferably 0.008 Pa or more and 0.02 Pa or less.

Thereafter, the transparent substrate 11 with the surface of the optical function layer 14 treated is sent to the vapor deposition device 3 by the rotation of the can roll 26 and the guide roll 22 .
Next, an antifouling layer forming step is performed in the chamber 33 of the vapor deposition device 3. In this embodiment, the antifouling layer forming step is performed on the laminate in which the surface of the outermost low refractive index layer 14b has been plasma treated in the plasma treatment step.
In the antifouling layer forming process, the guide roll 22 is rotated to transport the transparent substrate 11 having the treated surface of the optical functional layer 14 at a predetermined transport speed, while the evaporation source 43 is evaporated onto the surface of the optical functional layer 14.

In this embodiment, for example, an anti-fouling material made of a fluorine-based organic compound that will become the anti-fouling layer 15 is heated to its vapor pressure temperature using a heating device 53, and the resulting evaporated gas is supplied from a vapor deposition source 43 in a reduced pressure environment and adhered to the surface-treated optical function layer 14, forming the anti-fouling layer 15 by vacuum deposition. As the anti-fouling material, a compound made of a fluorine-modified organic group and a reactive silyl group (e.g., alkoxysilane) is preferably used as the fluorine-based organic compound. Examples of commercially available products include Optool DSX (manufactured by Daikin Corporation) and the KY-100 series (manufactured by Shin-Etsu Chemical Co., Ltd.).

The pressure during vacuum deposition of the antifouling layer 15 is preferably 0.05 Pa or less, more preferably 0.01 Pa or less, and particularly preferably 0.001 Pa or less. When the pressure during vacuum deposition is reduced to 0.05 Pa or less, the mean free path of the film-forming molecules is longer and the deposition energy is higher, resulting in a denser and better antifouling layer 15.

Using the method described above, it is possible to manufacture optical laminates 101 and 102 as shown in Figures 1 and 2.

The optical laminate according to this embodiment may be an optical laminate that does not have a hard coat layer 12 or an adhesion layer 13. When forming such an optical laminate, a substrate that does not have a hard coat layer 12, i.e., a substrate made of a transparent substrate 11, may be used, and the surface treatment process and adhesion layer formation process may be omitted. Furthermore, in this embodiment, "on the substrate" means that the substrate is located above the transparent substrate 11, and may not be in contact with the transparent substrate 11.

In the above embodiment, by performing the plasma treatment process under conditions in which a mixed gas of argon gas and water vapor is introduced, in addition to the hydroxyl groups that bond to Si on the outermost surface several nanometers from the surface of the optical function layer 14 generated by the argon gas plasma treatment, the hydroxyl groups generated by hydrolysis of SiO bonds near the outermost surface of the optical function layer 14 facilitate chemical reaction with the fluorine-based organic compound having a reactive silyl group that constitutes the anti-fouling layer 15. In other words, the amount of fluorine-based organic compound in the anti-fouling layer 15 formed on the optical function layer 14 can be increased, and even if an alkaline solution adheres to the surface of the optical laminates 101 and 102, the amount of exposure of the SiO bonds in the optical function layer 14 can be reduced. Here, by forming the low refractive index layer 14b in a dry atmosphere, the increase in hydroxyl groups and hydrolysis that do not contribute to bonding with the anti-fouling layer 15 within the low refractive index layer 14b can be suppressed, thereby suppressing deterioration of the optical properties.

Furthermore, the glow discharge treatment in the plasma treatment step for the low refractive index layer 14b can increase the surface energy of the optical function layer 14, making it easier to adhere the antifouling layer 15. The glow discharge makes the layer hydrophilic, reducing the water contact angle, and reducing the amount of fluorine-based organic compounds that cannot adhere to the substrate and become free.
According to this embodiment, an optical layered body having excellent long-term alkali resistance can be provided in this way.

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 invention as set forth in the claims. These embodiments and their modifications are included within the scope of the invention as set forth in the claims and their equivalents, as well as within the scope and spirit of the invention.

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.

Throughout this disclosure, singular expressions should be understood to include the plural concept, unless otherwise stated. Therefore, singular articles (e.g., "a," "an," "the," etc. in English) should be understood to include the plural concept, unless otherwise stated.

The following describes examples of the present invention. Note that the optical laminates produced in the following examples and comparative examples are examples that function as anti-reflection films, and the scope of the present invention is not limited to these examples.

(Example 1-1)
First, a resin film was prepared by forming a 4 μm thick acrylic resin coating (hard coat layer) containing silicon oxide fine particles on a TAC substrate having a thickness of 80 μm as a transparent substrate.

Next, using the roll-to-roll method, an adhesive layer was formed on the transparent substrate with the hard coat layer formed thereon by the method described below. Then, high refractive index layers and low refractive index layers were alternately formed as optical functional layers. After forming the low refractive index layer located on the uppermost surface of the optical functional layers, a plasma treatment process was performed, and an anti-fouling layer was then formed to produce an optical laminate (anti-reflection film).

The manufacturing device used was the manufacturing device 20 shown in Figure 4. The line speed was 2 m/min. The total pressure when forming the optical laminate was 1 Pa or less.

The hard coat layer 12 was subjected to a glow discharge treatment at a treatment speed of 400 W·min/m ^2. Then, on the hard coat layer 12 after the glow discharge treatment, a 5 nm thick adhesion layer 13 made of SiOx was formed by sputtering in a chamber with a pressure of 1.0 Pa or less, and an optical function layer 14 (laminate) made of a 15 nm thick Nb ₂ O ₅ film (high refractive index layer), a 38 nm thick SiO ₂ film (low refractive index layer), a 30 nm thick Nb ₂ O ₅ film (high refractive index layer), and a 102 nm thick SiO ₂ film (low refractive index layer) was formed on the adhesion layer. The high refractive index layer and the low refractive index layer were formed in a dry atmosphere without introducing H ₂ O.

Next, the low refractive index layer was plasma-treated in an atmosphere containing moisture and argon gas. The plasma treatment of the low refractive index layer surface was performed in an H ₂ O and Ar atmosphere while introducing water vapor and argon gas into the chamber. The total flow rate of water vapor and argon gas from the adjustment chamber 65 into the chamber 36 was 500 sccm, and the argon gas supply rate from the argon gas supply source 61 to the adjustment chamber 65 was 500 sccm. In this manner, in Example 1-1, the flow rate of water vapor in the mixed gas of water vapor and argon gas introduced into the chamber 36 was 10%, and the flow rate of argon gas was 90%. The flow rate of water vapor in the mixed gas of water vapor and argon gas introduced into the chamber 36 may be referred to as the target H ₂ O %. That is, in Example 1-1, the target H ₂ O % was 10%. The target H ₂ O % was based on an approximation curve for the average H ₂ O percentage obtained in advance. The flow rate of argon gas is determined according to the approximation curve and the target % of _H2O . The proportions of _H2O , Ar, _H2 , and _O2 in the atmosphere in chamber 36 were measured using a partial pressure vacuum gauge (manufactured by ULVAC, Inc., model number: CGM051). The proportion of _H2O in the atmosphere in chamber 36 was 9.4%. The proportion of _H2O in the atmosphere in chamber 36 may be referred to as _H2O %.

The approximation curve for the average H ₂ O ratio was obtained in advance by the following method.
First, using the apparatus used in Example 1-1, predetermined amounts of argon gas and water vapor are supplied into a chamber under the same environment as in Example 1-1. At this time, the flow rate of argon gas is measured using a mass flow meter installed between the argon gas supply source and the chamber, and the proportion of each gas composition in the chamber is measured using a partial pressure vacuum gauge installed in the chamber. The proportion of water vapor relative to the total mixed gas supplied into the chamber at argon gas rates of 10, 20, 50, 100, 150, 175, 200, 250, 300, 400, and 500 SCCM is measured and plotted on a graph. Next, an approximation curve for the dependence of the flow rate of water vapor in the total mixed gas on the argon gas flow rate is created using the nonlinear least squares method from the plotted data. The flow rate of argon gas required to produce a predetermined amount of water vapor can be determined from this approximation curve.

The electrode power density of the glow discharge treatment when the glow discharge treatment was performed on the outermost surface of the low refractive index layer was set to 4421 (W/m ² ).

Next, an anti-fouling layer 15 made of an alkoxysilane compound (KY-1901, manufactured by Shin-Etsu Chemical Co., Ltd.) with a perfluoropolyether group, which is a fluorine-containing organic compound, was formed on the optical functional layer by vapor deposition at a pressure of 0.01 Pa or less in the vapor deposition chamber and a vapor deposition temperature of 230°C, to an optical thickness of 4 nm. The layer was then wound into a roll to obtain the optical laminate (anti-reflection film) of Example 1.

(1) Scratch resistance test using a rag (nonwoven fabric wiper) An abrasion test was conducted except that a rag (nonwoven fabric wiper) (Bencotto Lint Free CT-8, manufactured by Asahi Chemical Industry Co., Ltd.) was used as the friction body. The test settings were a load of 250 g/cm ² , a stroke of 25 mm, and a speed of 50 mm/s. The friction body was subjected to horizontal reciprocating motion 4,000 times.

The water contact angle of the test piece after rubbing was measured, and the water contact angles of the test piece before rubbing and after 4,000 horizontal reciprocating movements were determined. The test was conducted within 30 minutes after rubbing.

(2) Alkali Resistance Test The back surface of the optical laminate was attached to a black acrylic plate with transparent tape to eliminate back surface reflection. The optical properties of this untreated optical laminate were measured using the SCI method in the CIE 1976 (L ^* a ^* b ^* ) color space, including lightness L ^* , chromaticity a ^* , and b ^* . An integrating sphere spectrophotometer (SP-64, manufactured by X-rite Corporation) was used for the optical measurements. The settings were a D65 light source and a viewing angle of 10°.

In addition, a 0.1 (mol/L) aqueous sodium hydroxide solution was prepared. The optical laminate was placed in a cylindrical member with an inner diameter of 38 mm, a reagent was dropped into the cylindrical member, and the upper opening was covered with a glass plate. Then, after leaving the liquid temperature at 55°C for 4 hours, each test piece was washed with distilled water to obtain a treated sample. The optical properties of the optical laminate after leaving for 4 hours were evaluated in the same manner as for the untreated optical laminate. The ΔE value of the optical laminate after 4 hours of treatment, expressed by the following formula (1), was measured relative to the untreated optical laminate.
ΔE ^* _ab = {(L ^* ₂ - L ^* ₁ ) ² + (a ^* ₂ - ^{a *} ₁ ) ² + (b ^* ₂ - b ^* ₁ ) ² } ^1/2 ... (1)
(Wherein, L ^* ₁ : lightness before adding NaOH aq, L ^* ₂ : lightness after a predetermined time has elapsed since adding NaOH aq, a ^* ₁ : chromaticity before adding NaOH aq, a ^* ₂ : chromaticity after allowing to stand for a predetermined time since adding NaOH aq, b ^* ₁ : chromaticity before adding NaOH aq, b ^* ₂ : chromaticity after allowing to stand for a predetermined time since adding NaOH aq)

(3) Fluorine Amount Measurement Test The fluorine amount (cps: counts per unit time) of the optical laminate (test piece) was measured (fluorine amount before cleaning (fluorine amount in the initial state)).

The fluorine content was measured using an X-ray photoelectron spectroscopy for Chemical Analysis (ESCA) (PHI5000 VersaProbeIII, ULVAC-PHI, Inc.) and X-ray fluorescence analysis (XRF) (EDX-8000, Shimadzu Corporation). The fluorine value (cps) determined using the X-ray photoelectron spectroscopy and X-ray fluorescence analysis was the average value calculated from the results of measurements taken initially with n=3.

(4) _SiO2 Bond Energy Measurement Test The SiO2 bond energy of the optical laminate was measured from the antifouling layer side by the X-ray photoelectron spectroscopy (ESCA) used in (3) under the following conditions. ESCA can measure _{the SiO2} bond energy at a distance of several nm from the surface of the optical laminate.
For reference, the bond energy of silicon element is 99.2 eV, the bond energy of silicone is 102.4 eV, and the bond energy of _SiO2 is 103.6 eV. In other words, if it is below 103.6 eV, it can be seen that the anti-fouling layer is thicker or formed at a higher density. Similarly, a WIDE scan was also performed to confirm the metal elements contained in the optical laminate. Metal elements other than those constituting the optical laminate were also detected, and the inclusion of metal elements other than the metals constituting the metal oxide used in the optical laminate (metal elements other than Nb and Si in Example 1-1) was confirmed.
ESCA measurement conditions: Measurement: narrow scan, wide scan; X-ray source: monoAl
・X-ray gun: 200 μmφ50w15V
・Dwel (1step time): 20ms
Step (measurement interval): 0.05 eV
Sweeps (cumulative): 10 times Pass energy: 55 eV

(Examples 1-2 to 1-5)
An optical laminate was produced and evaluated in the same manner as in Example 1-1, except that the amount of argon gas supplied from the argon gas supply source 61 to the adjustment chamber 65 in the plasma treatment process for the low refractive index layer surface was adjusted to the target H ₂ O % as shown in Table 1.

(Examples 2-1 to 2-3)
In Examples 2-1 to 2-5, optical laminates were produced and evaluated in the same manner as in Example 1-1, except that in the plasma treatment step on the low refractive index layer surface, the electrode power density during glow discharge treatment was set to 7516 (W/m ² ), and the amount of argon gas supplied from argon gas supply source 61 to adjustment chamber 65 was adjusted to the target H ₂ O % shown in Table 1. The H ₂ O % during the plasma treatment step was as shown in Table 3.

(Examples 3-1 to 3-5)
In Examples 3-1 to 3-5, optical laminates were produced and evaluated in the same manner as in Example 1-1, except that in the plasma treatment step on the low refractive index layer surface, the electrode power density during glow discharge treatment was set to 8842 (W/m ² ), and the amount of argon gas supplied from the argon gas supply source 61 to the adjustment chamber 65 was adjusted to the target H ₂ O % shown in Table 1. The H ₂ O % during the plasma treatment step was as shown in Table 3.

(Examples 4-1 to 4-5)
In Examples 4-1 to 4-5, optical laminates were produced and evaluated in the same manner as in Example 1-1, except that in the plasma treatment step on the low refractive index layer surface, the electrode power density during glow discharge treatment was set to 13,263 (W/m ² ), and the amount of argon gas supplied from argon gas supply source 61 to adjustment chamber 65 was adjusted to the target H ₂ O % shown in Table 1. The H ₂ O % during the plasma treatment step was as shown in Table 3.

(Examples 5-1 to 5-3)
In Examples 5-1 to 5-3, optical laminates were produced and evaluated in the same manner as in Example 1-1, except that in the plasma treatment step on the low refractive index layer surface, the electrode power density during glow discharge treatment was set to 17,684 (W/m ² ), and the amount of argon gas supplied from argon gas supply source 61 to adjustment chamber 65 was adjusted to the target H ₂ O % shown in Table 1. The H ₂ O % during the plasma treatment step was as shown in Table 3.

(Comparative Example 1)
An optical laminate was produced in the same manner as in Example 1-1, except that during the surface treatment of the low refractive index layer surface and the glow discharge treatment, water vapor was not introduced as a reactive gas into chamber 36, and only argon gas was flowed. The H ₂ O % during the plasma treatment step was as shown in Table 4.

(Comparative Example 2)
An optical laminate was produced in the same manner as in Example 2-1, except that during the surface treatment of the low refractive index layer surface and the glow discharge treatment, water vapor was not introduced as a reactive gas into chamber 36, and only argon gas was flowed. The H ₂ O % during the plasma treatment step was as shown in Table 4.

(Comparative Example 3)
An optical laminate was produced in the same manner as in Example 1-1, except that during the surface treatment of the low refractive index layer surface and the glow discharge treatment, the electrode power density was set to 17684 W/m ² , and only argon gas was flowed into the chamber 36 without introducing water vapor as a reactive gas. The H ₂ O % during the plasma treatment step was as shown in Table 4.

(Comparative Examples 4-1 to 4-4)
An optical laminate was produced in the same manner as in Example 1-1, except that during the surface treatment of the low refractive index layer surface, the glow discharge treatment, the electrode power density was set to 1326 W/m ² and the amount of argon gas supplied from the argon gas supply source 61 to the adjustment chamber 65 was adjusted to the target H ₂ O % shown in Table 1. The H ₂ O % during the plasma treatment step was as shown in Table 4.

As described above, the properties of the optical laminates produced in the examples and comparative examples were evaluated.
The measurement results of the properties of the optical laminates of Examples 1-1 to 5-3 are summarized in Table 1, and the measurement results of the properties of the optical laminates of Comparative Examples 1 to 4-4 are summarized in Table 2. In Tables 1 and 2, the column "Detection of metal elements such as Al by ESCA" indicates "◯" if contamination with metal elements other than the metals that make up the metal oxide used in the optical laminates was detected by ESCA, and indicates "-" if not detected. In addition, the proportions of each gas in the atmosphere in chamber 36 and the total pressure (TP value) in chamber 36, measured with a partial pressure vacuum gauge, are summarized in Table 3 for Examples 1-1 to 5-3, and in Table 4 for Comparative Examples 1 to 4-4.

By comparing Examples 1-1 to 5-3 with Comparative Examples 1 to 4-4, it was confirmed that by flowing H ₂ O as a reactive gas in the plasma treatment step, superior alkali resistance was exhibited compared to when H ₂ O was not introduced as a reactive gas. This shows that the presence of H ₂ O gas during the plasma treatment of the low refractive index layer improves alkali resistance after the formation of the antifouling layer.

However, when comparing Comparative Examples 4-1 to 4-5 with Examples 1-1 to 5-3, even when the same target H ₂ O % and the H ₂ O % range are used in the Examples and Comparative Examples, the alkali resistance is lower in Comparative Examples 4-1 to 4-5. This result shows that even when H ₂ O gas is introduced, a certain level of electrode power density during the plasma treatment process is required to improve alkali resistance.

This shows that changing the conditions of the plasma treatment step increased the amount of fluorine-based organic compounds in the antifouling layer formed on the low-refractive-index layer. The increase in the amount of fluorine-based organic compounds in the antifouling layer reduces the area of _SiO2 constituting the low-refractive-index layer that comes into contact with water, suppressing hydrolysis of siloxane bonds and the substitution of H in hydroxyl groups with alkali metals, resulting in the alkali resistance described above.

1. Sputtering device, 2A. Pretreatment device, 2B. Pretreatment device, 3. Vapor deposition device, 4. Device, 11. Transparent substrate, 12. Hard coat layer, 13. Adhesion layer, 14. Optical functional layer, 14a. High refractive index layer, 14b. Low refractive index layer, 15. Antifouling layer, 20. Manufacturing device, 21. Vacuum pump, 22. Guide roll, 23. Roll, 25. Film-forming roll, 26. Can roll, 31. Chamber, 32. Chamber, 34. Chamber, 41. Film-forming section, 42. Plasma discharge device, 101, 102. Optical laminate

Claims (11)

A method for producing an optical laminate comprising: a substrate; a high refractive index layer provided on the substrate directly or via another layer; a low refractive index layer formed on the high refractive index layer and containing SiO ₂ as a main component; and an antifouling layer formed on the low refractive index layer,
a high refractive index layer forming step of forming a high refractive index layer;
a low refractive index layer forming step of forming the low refractive index layer in a dry atmosphere;
a plasma treatment step of plasma treating the low refractive index layer;
and an antifouling layer forming step of forming an antifouling layer on the surface,
In the plasma treatment step, the low refractive index layer is plasma treated at an electrode power density of 4400 W/m ² or more and 18000 W/m ² or less in an environment where a mixed gas of water vapor and argon gas is introduced. The method for producing an optical laminate described in claim 1, wherein the flow rate of water vapor in the mixed gas of water vapor and argon gas introduced in the plasma treatment step is 10% or more and 90% or less. The method for producing an optical laminate according to claim 1 or 2, wherein an electrode power density in the plasma treatment step is 7000 W/m ² or more and 14000 W/m ² or less. The method for producing an optical laminate according to claim 1 or 2, wherein the low refractive index layer is formed by sputtering in the low refractive index layer formation step. In the antifouling layer forming step, the antifouling layer is formed by a vapor deposition method,
The method for producing an optical laminate according to claim 1 , wherein the antifouling layer contains a compound having an alkoxysilyl group and a fluorine-modified organic group. The method for producing an optical laminate according to claim 1 , wherein in the plasma treatment step, a proportion of H ₂ O in an atmosphere in a space where the low refractive index layer is plasma treated is 6.5% or more and 50% or less. A substrate, a high refractive index layer provided on the substrate directly or via another layer, a low refractive index layer formed on the high refractive index layer and containing _SiO2 as a main component, and an antifouling layer formed on the low refractive index layer,
An optical laminate having a ΔE value represented by the following formula (1) of 8 or less after 0.1 (mol/L) NaOH aqueous solution is dropped and the laminate is allowed to stand at 55° C. for 4 hours: ΔE ^* _ab = {(L ^* ₂ - L ^* ₁ ) ² + (a ^* ₂ - ^a* ₁ ) ² + (b ^* ₂ - b ^* ₁ ) ² } ^1/2 (1)
(Wherein, L ^* ₁ : brightness before adding NaOH aq, L ^* ₂ : brightness after a predetermined time has elapsed since adding NaOH aq, a ^* ₁ : chromaticity before adding NaOH aq, a ^* ₂ : chromaticity after leaving the solution for a predetermined time since adding NaOH aq, b ^* ₁ : chromaticity before adding NaOH aq, b ^* ₂ : chromaticity after leaving the solution for a predetermined time since adding NaOH aq). The optical laminate according to claim 7, wherein the bond energy of _SiO2 measured by X-ray photoelectron spectroscopy (ESCA) from the antifouling layer side is 103.25 eV or less. the high refractive index layer is composed of an oxide of a first metal element,
the low refractive index layer is composed of an oxide of a second metal element,
The optical laminate according to claim 7 , wherein the metal elements detected by ESCA measurement are only the first metal element and the second metal element. an adhesive layer is further provided between the substrate and the high refractive index layer,
the high refractive index layer is composed of an oxide of a first metal,
the low refractive index layer is composed of an oxide of a second metal,
the adhesion layer is composed of an oxide of a third metal,
The optical laminate according to claim 7 , wherein metal elements detected by ESCA measurement are only the first metal element, the second metal element, and the third metal element. An article comprising the optical laminate described in any one of claims 7 to 10.