WO2024090540A1 - Antireflection film - Google Patents

Abstract

The purpose of the present invention is to provide an antireflection film having excellent antireflection properties and scratch resistance and also having high antifouling properties and wear durability.　This antireflection film 10 has a base material film 12, a hard coat layer 14 formed on the surface of the base material film 12, a low-refractive-index layer 16 formed on the surface of the hard coat layer 14, a primer layer 17 formed on the surface of the low-refractive-index layer 16, and an antifouling layer 18 formed on the surface of the primer layer 17, wherein: the antifouling layer 18 is composed of a cured product of a composition containing a fluorine-containing (meth)acrylate; the content of the fluorine-containing (meth)acrylate in the antifouling layer 18 is at least 90 mass% with respect to the total amount of solid contents of the antifouling layer 18; the thickness d_LR of the low-refractive-index layer 16 is at least 46 nm; the thickness d_PR of the primer layer 17 is at least 8 nm; and the total thickness d_LR+d_PR of the low-refractive-index layer 16 and the primer layer 17 is 60-100 nm.

Description

Anti-reflective film

The present invention relates to an anti-reflective film, and more specifically, to an anti-reflective film suitable for use on the surfaces of displays such as liquid crystal displays, organic electroluminescence displays, and touch panels for smartphones and the like.

Anti-reflective films are sometimes placed on the display surfaces of liquid crystal displays, organic electroluminescence displays, touch panels of smartphones, and other devices to prevent external light from being reflected on the screen. Known anti-reflective films have a hard coat layer and an anti-reflective layer (low refractive index layer) in that order on a substrate film. For example, in Patent Document 1, filed by the applicant, the composition of the low refractive index layer formed on the surface of the hard coat layer is examined to improve the anti-reflective properties, scratch resistance, and stain resistance of the anti-reflective film. In Patent Document 1, a fluorine-containing compound is contained in the low refractive index layer, which contributes to improving the stain resistance.

International Publication No. 2021/020504

Anti-reflection films, particularly those placed on the surface of a touch panel and that are frequently touched by fingers, are required to have high anti-soiling properties. As disclosed in Patent Document 1, the anti-soiling properties of an anti-reflection film can be improved by adding a substance with anti-soiling properties, such as a fluorine-containing compound, to the low refractive index layer that constitutes the anti-reflection film. On the other hand, a form in which an anti-soiling layer containing such substances with anti-soiling properties is provided on the surface of the low refractive index layer as a layer independent of the low refractive index layer is also used. However, even if an anti-soiling layer is provided, there are cases in which a sufficiently high anti-soiling property cannot be obtained, and repeated contact with fingers may cause the surface to wear and reduce the anti-soiling property. In anti-reflection films that are frequently touched by fingers, in addition to having high anti-reflection properties and anti-soiling properties, from the viewpoint of durability during use, it is important that the film has high scratch resistance and high abrasion resistance.

The problem that the present invention aims to solve is to provide an anti-reflective film that has excellent anti-reflective properties and scratch resistance, as well as high stain resistance and abrasion resistance.

In order to solve the above problems, the anti-reflection film according to the present invention has the following configuration.
[1] The antireflection film according to the present invention comprises a substrate film, a hard coat layer formed on a surface of the substrate film, a low refractive index layer formed on the surface of the hard coat layer, a primer layer formed on the surface of the low refractive index layer, and an antifouling layer formed on the surface of the primer layer, wherein the antifouling layer is composed of a cured product of a composition containing a fluorinated (meth)acrylate, the content of the fluorinated (meth)acrylate in the antifouling layer is 90 mass% or more based on the total solid content of the antifouling layer, the thickness d _LR of the low refractive index layer is 46 nm or more, the thickness d _PR of the primer layer is 8 nm or more, and the total thickness d _LR +d _PR of the low refractive index layer and the primer layer is 60 nm or more and 100 nm or less.

[2] In the above aspect [1], the low refractive index layer is preferably composed of a cured product of a composition containing a binder resin containing a (meth)acrylate compound, inorganic oxide particles, and hollow silica particles, and the primer layer is preferably composed of a cured product of a composition that contains a binder resin containing a (meth)acrylate compound and does not contain particles made of an inorganic oxide.

[3] In the embodiment of [2] above, the binder resin contained in the primer layer may be the same as the binder resin contained in the low refractive index layer.

[4] In the above embodiment [2] or [3], the low refractive index layer may not contain a fluorine-containing compound.

The anti-reflection film according to the present invention having the above-mentioned configuration [1] comprises a substrate film, a hard coat layer formed on the surface of the substrate film, a low refractive index layer formed on the surface of the hard coat layer, a primer layer formed on the surface of the low refractive index layer, and an anti-stain layer formed on the surface of the primer layer, the anti-stain layer being composed of a cured product of a composition containing a fluorine-containing (meth)acrylate, the content of the fluorine-containing (meth)acrylate in the anti-stain layer being 90 mass% or more based on the total solid content of the anti-stain layer, the thickness d _LR of the low refractive index layer being 46 nm or more, the thickness d _PR of the primer layer being 8 nm or more, and the total thickness d _LR +d _PR of the low refractive index layer and the primer layer being 60 nm or more and 100 nm or less. The anti-reflection film has excellent anti-stain properties, scratch resistance, and abrasion resistance by being provided with an anti-stain layer having the above-mentioned composition. A primer layer is formed between the antifouling layer and the low refractive index layer, and the thicknesses of the primer layer and the low refractive index layer are as described above, thereby further enhancing the antifouling properties and abrasion resistance while maintaining the antireflection properties and scratch resistance of the antireflection film.

In the above aspect [2], the low refractive index layer is composed of a cured product of a composition containing a binder resin containing a (meth)acrylate compound, inorganic oxide particles, and hollow silica particles, and the primer layer is composed of a cured product of a composition containing a binder resin containing a (meth)acrylate compound and no particles made of an inorganic oxide. Therefore, due to the contribution of the low refractive index layer and the primer layer, the anti-reflection film has excellent optical properties such as antifouling properties, scratch resistance, abrasion resistance, and anti-reflection properties.

In the above embodiment [3], the binder resin contained in the primer layer is the same as the binder resin contained in the low refractive index layer, so that the adhesion between the low refractive index layer and the primer layer is increased, and this effectively improves the abrasion resistance of the anti-reflection film.

In the above embodiment [4], the low refractive index layer does not contain a fluorine-containing compound. In the anti-reflection film of the present invention, since the anti-stain layer exhibits high anti-stain properties, it is not necessary to include a fluorine-containing compound in the low refractive index layer in order to improve the anti-stain properties. By making the low refractive index layer free of a fluorine-containing compound, the scratch resistance of the anti-reflection film is less likely to be impaired.

1 is a cross-sectional view of an antireflection film according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view of an antireflection film according to a second embodiment of the present invention. FIG. 4 is a cross-sectional view of an antireflection film according to a third embodiment of the present invention. FIG. 11 is a cross-sectional view of an antireflection film according to a fourth embodiment of the present invention.

The present invention will be described in detail below. In this specification, various physical properties refer to values at room temperature in the atmosphere unless otherwise specified. In addition, in this specification, the refractive index of a substance and a substance layer refers to the refractive index at a measurement wavelength of 589.3 nm unless otherwise specified.

<Antireflection film of first embodiment>
Fig. 1 is a cross-sectional view of an anti-reflection film according to a first embodiment of the present invention. As shown in Fig. 1, an anti-reflection film 10 according to a first embodiment of the present invention has a substrate film 12, a hard coat layer 14 formed on the surface of the substrate film 12, a low refractive index layer 16 formed on the surface of the hard coat layer 14, a primer layer 17 formed on the surface of the low refractive index layer 16, and an anti-stain layer 18 formed on the surface of the primer layer 17. In this embodiment, the above-mentioned layers are laminated in order without any other layer therebetween. The anti-stain layer 18 is the layer exposed on the outermost surface of the entire anti-reflection film 10.

(Base film)
The base film 12 is not particularly limited as long as it has transparency. Examples of the base film 12 include a transparent polymer film and a glass film. Transparency refers to a total light transmittance of 50% or more in the visible light wavelength region, and the total light transmittance is more preferably 85% or more. The total light transmittance can be measured in accordance with JIS K7361-1 (1997). The thickness of the base film 12 is not particularly limited, but is preferably in the range of 2 μm to 500 μm in terms of excellent handleability. More preferably, it is in the range of 2 μm to 200 μm. Note that, although the term "film" generally refers to a film having a thickness of less than 0.25 mm, even if the thickness is 0.25 mm or more, it is included in the "film" even if the thickness is 0.25 mm or more, as long as it can be wound into a roll.

The polymeric material of the base film 12 may be a polyester resin such as polyethylene terephthalate resin or polyethylene naphthalate resin, a polycarbonate resin, a poly(meth)acrylate resin, a polystyrene resin, a polyamide resin, a polyimide resin, a polyacrylonitrile resin, a polyolefin resin such as polypropylene resin, polyethylene resin, polycycloolefin resin, or cycloolefin copolymer resin, a cellulose-based resin such as triacetyl cellulose resin or diacetyl cellulose resin, a polyphenylene sulfide resin, a polyvinyl chloride resin, a polyvinylidene chloride resin, or a polyvinyl alcohol resin. The polymeric material of the base film 12 may be composed of only one of these materials, or may be composed of a combination of two or more of these materials. Among these, from the viewpoint of optical properties and durability, polyethylene terephthalate resin, polyimide resin, polycarbonate resin, poly(meth)acrylate resin, polycycloolefin resin, cycloolefin copolymer resin, or triacetyl cellulose resin is more preferable.

The substrate film 12 may be composed of a single layer containing one or more of the above polymeric materials, or may be composed of two or more layers, such as a layer containing one or more of the above polymeric materials and a layer containing one or more of a different polymeric material.

(Hard Coat Layer)
The hard coat layer 14 contributes to improving the scratch resistance of the anti-reflection film 10. The hard coat layer 14 is composed of a cured product of an ionizing radiation curable composition containing a (meth)acrylate compound having a reactive group. The ionizing radiation means electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules. Examples of the ionizing radiation include ultraviolet rays (UV), X-rays, gamma rays, and other electromagnetic waves, electron beams (EB), alpha rays, ion beams, and other charged particle beams. Among these, ultraviolet rays (UV) are particularly preferred from the viewpoint of productivity. Hereinafter, the ionizing radiation curable composition may be simply referred to as a curable composition. In addition, in this specification, "(meth)acrylate" means "at least one of acrylate and methacrylate". "(meth)acryloyl" means "at least one of acryloyl and methacryloyl". "(meth)acrylic" means "at least one of acrylic and methacrylic". The "(meth)acrylate compound" is a compound having a (meth)acryloyl group, and examples of such compounds include monomers, oligomers, prepolymers, etc. Hereinafter, the (meth)acrylate compound may be simply referred to as "(meth)acrylate."

The (meth)acrylate may be a monofunctional (meth)acrylate or a polyfunctional (meth)acrylate. Alternatively, it may be a combination of a monofunctional (meth)acrylate and a polyfunctional (meth)acrylate. From the viewpoint of improving curability, etc., it is more preferable that the curable composition contains a polyfunctional (meth)acrylate as the (meth)acrylate.

(Meth)acrylates include urethane (meth)acrylates, silicone (meth)acrylates, alkyl (meth)acrylates, and aryl (meth)acrylates. Of these, urethane (meth)acrylates, particularly urethane (meth)acrylate oligomers, are preferred. Specific examples of urethane (meth)acrylates include those obtained by reacting a polyisocyanate compound with a hydroxyl group-containing (meth)acrylate compound and, if necessary, a polyol compound. Examples of polyisocyanate compounds include diisocyanate compounds such as hexamethylene diisocyanate, isophorone diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and 4,4'-diphenylmethane diisocyanate, as well as their nurate modified products, adduct modified products, and biuret modified products. Examples of the hydroxyl group-containing (meth)acrylate compound include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, trimethylolpropane diacrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and their polyoxyalkylene modified products and polylactone modified products. Examples of the polyol compound include ethylene glycol, propylene glycol, butanediol, hexanediol, polyoxyethylene glycol, polyoxypropylene glycol, glycerin, trimethylolpropane, pentaerythritol, biphenol, bisphenol, and the like. When the curable composition for forming the hard coat layer 14 contains urethane (meth)acrylate as the ultraviolet curable resin, the hard coat layer 14 has a moderate flexibility, so that the anti-reflection film 10 has high bending resistance, and can be suitably used for flexible displays that are repeatedly bent, such as foldable displays and rollable displays. In addition, even if the base film 12 is made of, for example, polycycloolefin or cycloolefin copolymer, which is relatively prone to cracking, cracking of the base film 12 is easily prevented.

It is preferable that the (meth)acrylate constituting the curable composition further contains a pentaerythritol (meth)acrylate compound. Specific examples of pentaerythritol (meth)acrylate compounds include pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol tetra(meth)acrylate, tripentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, and tripentaerythritol octa(meth)acrylate. In particular, it is preferable that the curable composition contains pentaerythritol tri(meth)acrylate.

The curable composition forming the hard coat layer 14 may or may not contain a non-UV curable resin in addition to the UV curable resin. The curable composition forming the hard coat layer 14 may also contain a photopolymerization initiator. If necessary, it may also contain additives that can be generally added to curable compositions. Examples of additives include dispersants, leveling agents, defoamers, thixotropic agents, antifouling agents, antibacterial agents, flame retardants, slip agents, antistatic agents, inorganic particles, and resin particles. If necessary, it may also contain a solvent.

Non-UV curable resins include thermoplastic resins and thermosetting resins. Thermoplastic resins include polyester resins, polyether resins, polyolefin resins, and polyamide resins. Thermosetting resins include unsaturated polyester resins, epoxy resins, alkyd resins, and phenolic resins.

Examples of photopolymerization initiators include alkylphenone-based, acylphosphine oxide-based, and oxime ester-based photopolymerization initiators. Examples of alkylphenone-based photopolymerization initiators include 2,2'-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one. Examples of the acylphosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, etc. Examples of the acylphosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, etc. Examples of oxime ester photopolymerization initiators include 1,2-octanedione, 1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime), ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyloxime), etc. The photopolymerization initiator may be used alone or in combination of two or more of these.

The content of the photopolymerization initiator is preferably in the range of 0.1% by mass to 10% by mass based on the total solid content of the curable composition. More preferably, it is 1% by mass or more and 5% by mass or less.

The inorganic particles and resin particles are added to the hard coat layer 14 for the purpose of, for example, preventing blocking of the hard coat layer 14 and adjusting the refractive index of the hard coat layer 14. The inorganic particles or resin particles added form fine surface irregularities on the hard coat layer 14, which makes it easier to prevent blocking, which occurs when the hard coat film consisting of the base film 12 and the hard coat layer 14 before the low refractive index layer 16 is formed, is wound into a roll.

Inorganic particles capable of adjusting the refractive index of the hard coat layer 14 include metal oxide particles made of oxides of metals such as titanium, zirconium, tin, zinc, silicon, niobium, aluminum, chromium, magnesium, germanium, gallium, antimony, and platinum. These may be used alone as optically adjustable inorganic particles, or in combination of two or more. Among these, titanium oxide particles and zirconium oxide particles are particularly preferred from the viewpoint of achieving both a high refractive index and excellent transparency. In addition, examples of resin particles include resin particles made of resins such as (meth)acrylic resin, styrene resin, styrene-(meth)acrylic resin, urethane resin, polyamide resin, silicone resin, epoxy resin, phenolic resin, polyethylene resin, and cellulose. These may be used alone as resin particles, or in combination of two or more.

The thickness of the hard coat layer 14 is not particularly limited, but from the viewpoint of having sufficient hardness, it is preferably 0.5 μm or more. More preferably, it is 0.75 μm or more. Furthermore, from the viewpoint of easily suppressing curling due to the difference in thermal shrinkage with the base film 12, it is preferably 20 μm or less. More preferably, it is 10 μm or less. The thickness of the hard coat layer 14 is the thickness of a relatively smooth portion in the thickness direction that does not have irregularities due to inorganic particles or resin particles.

From the viewpoint of suppressing interference unevenness caused by the difference in refractive index between the transparent substrate film 12 and the hard coat layer 14, the refractive index of the hard coat layer 14 is preferably within the range of 1.49 to 1.56.
The arithmetic mean roughness Ra of the surface of the hard coat layer 14 on which the surface irregularities are formed is preferably within a range of 0.3 nm or more and 20 nm or less from the viewpoint of suppressing blocking, etc., and more preferably 0.5 nm or more and 10 nm or less.

Solvents used in the curable composition that forms the hard coat layer 14 include alcohol-based solvents such as ethanol, isopropyl alcohol (IPA), n-butyl alcohol (NBA), ethylene glycol monomethyl ether (EGM), ethylene glycol monoisopropyl ether (IPG), propylene glycol monomethyl ether (PGM), and diethylene glycol monobutyl ether; ketone-based solvents such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone, and acetone; aromatic solvents such as toluene and xylene; ester-based solvents such as ethyl acetate (EtAc), propyl acetate, isopropyl acetate, and butyl acetate (BuAc); and amide-based solvents such as N-methylpyrrolidone, acetamide, and dimethylformamide. These solvents may be used alone or in combination of two or more.

The solids concentration of the curable composition (concentration of components other than the solvent) may be appropriately determined taking into consideration the coatability, film thickness, etc. For example, it may be 1% by mass or more and 90% by mass or less, 1.5% by mass or more and 80% by mass or less, or 2% by mass or more and 70% by mass or less, etc.

(Low Refractive Index Layer)
In the antireflection film 10 according to this embodiment, a low refractive index layer 16 is provided as an antireflection layer on the surface of the hard coat layer 14. The low refractive index layer 16 has a refractive index lower than that of the hard coat layer 14, and exerts an antireflection effect due to the difference in refractive index between the low refractive index layer 16 and the hard coat layer 14.

The low refractive index layer 16 is not particularly limited in composition, but is preferably made of a cured product of a composition containing a binder resin, inorganic oxide particles, and hollow silica particles. In particular, it is preferably made of a cured product of an ionizing radiation curable composition containing these components. A suitable composition is described below.

From the viewpoint of improving the scratch resistance of the low refractive index layer 16, it is preferable that the binder resin be a thermosetting compound or an ionizing radiation curable compound such as an ultraviolet curable compound. From the viewpoint of the productivity of the anti-reflection film 10, it is preferable that the binder resin be made of an ultraviolet curable compound.

Examples of ultraviolet-curable resins include monomers, oligomers, and prepolymers that have a reactive group that is reactive to ultraviolet light. Examples of the reactive group that is reactive to ultraviolet light include radical polymerization type reactive groups that have an ethylenically unsaturated bond, such as acryloyl groups, methacryloyl groups, allyl groups, and vinyl groups, and cationic polymerization type reactive groups, such as oxetanyl groups. Of these, acryloyl groups, methacryloyl groups, and oxetanyl groups are more preferred, with acryloyl groups and methacryloyl groups being particularly preferred. In other words, it is particularly preferred to use a (meth)acrylate compound.

Examples of (meth)acrylate compounds include urethane (meth)acrylate, silicone (meth)acrylate, alkyl (meth)acrylate, and aryl (meth)acrylate. The (meth)acrylate may be composed of only monofunctional (meth)acrylate, may be composed of only polyfunctional (meth)acrylate, or may be composed of a combination of monofunctional (meth)acrylate and polyfunctional (meth)acrylate. It is more preferable that the (meth)acrylate contains a polyfunctional (meth)acrylate.

　Monofunctional (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, and deci aryl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, bornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, Cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 1-naphthylmethyl (meth)acrylate, 2-naphthylmethyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxy-2-methylethyl (meth)acrylate, phenoxyethoxyethyl (meth)acrylate, 3-phenoxy-2-hydroxypropyl (meth)acrylate, 2-phenylphenoxyethyl (meth)acrylate, 4-phenylphenoxyethyl (meth)acrylate, 3-(2-phenylphenyl)-2-hydroxypropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, butoxyethyl (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, methoxyethylene glycol (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypolypropylene glycol (meth)acrylate, etc.

Examples of polyfunctional (meth)acrylates include difunctional (meth)acrylates, trifunctional (meth)acrylates, and tetrafunctional (meth)acrylates. More specifically, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and trimethylolpropane tri(meth)acrylate. , pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tripentaerythritol tetra(meth)acrylate, tripentaerythritol penta(meth)acrylate, tripentaerythritol hexa(meth)acrylate, tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate, etc.

The ultraviolet-curable resin may be composed of one type of the above-mentioned (meth)acrylate alone, or may be composed of two or more types. From the viewpoint of improving scratch resistance, the ultraviolet-curable resin preferably contains a polyfunctional (meth)acrylate having five or more functional groups, and it is also preferable to increase the content of the polyfunctional (meth)acrylate having five or more functional groups.

The polyfunctional (meth)acrylate preferably contains a dimer. The dimer of the polyfunctional (meth)acrylate has an excellent curing speed and can easily increase the curing rate of the curable composition, thereby further improving the scratch resistance. In particular, it is preferable to contain at least one selected from the group consisting of dimers of pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate, and it is more preferable to contain at least one selected from the group consisting of dimers of pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

From the viewpoints of scratch resistance, transparency, and solubility in solvents, the content of the above dimer is preferably in the range of 25% by mass or more and 50% by mass or less, based on the total solid content of the polyfunctional (meth)acrylate. More preferably, it is 30% by mass or more and 40% by mass or less.

The inorganic oxide particles, when contained in the low refractive index layer 16, form convex portions on the surface of the low refractive index layer 16. The inorganic oxide particles form convex portions on the surface of the low refractive index layer 16, which allows the low refractive index layer 16 to have good scratch resistance.

The inorganic oxide particles may be solid or hollow. It is preferable that the inorganic oxide particles are solid. A solid particle is a particle that does not have a cavity inside the particle, and the cavity ratio is less than 5% of the volume of the solid particle. A hollow particle is a particle that has a cavity inside the particle, and the cavity ratio is 5% or more of the volume of the hollow particle. When the inorganic oxide particles are solid particles, the scratch resistance of the low refractive index layer 16 is improved, and the scratch resistance of the anti-reflection film 10 is improved. When the inorganic oxide particles are hollow particles, the refractive index of the low refractive index layer 16 can be lowered to reduce light reflection. In the hollow particles, the cavity ratio is preferably 10% or more and 80% or less of the volume of the hollow particles. When the cavity ratio is 10% or more, the refractive index can be lowered to reduce light reflection. It is more preferable that the cavity ratio is 20% or more, and even more preferable that the cavity ratio is 30% or more. On the other hand, when the cavity ratio is 80% or less, the decrease in dispersibility of the inorganic oxide particles can be suppressed. More preferably, it is 60% or less.

Examples of inorganic oxide particles include metal oxide particles made of oxides of metals such as zirconium, silicon, aluminum, and calcium. These may be used alone as inorganic oxide particles, or two or more may be used in combination. Among these, silica particles and alumina particles are preferred, with alumina particles being particularly preferred, from the standpoints of low refractive index, excellent transparency, and high hardness.

The shape of the inorganic oxide particles is not particularly limited, and may be spherical, needle-like, scaly, rod-like, fibrous, amorphous, etc. Of these, spherical is preferred.

In order to form convex portions on the surface of the low refractive index layer 16 and obtain good scratch resistance, the difference (r-d _LR ) between the average particle diameter r of the inorganic oxide particles and the thickness d _LR of the low refractive index layer 16 is preferably 10 nm or more. The difference (r-d _LR ) is more preferably 15 nm or more, and even more preferably 18 nm or more. On the other hand, from the viewpoint of suppressing the height of the formed convex portions to maintain transparency, the difference (r-d _LR ) is 300 nm or less. More preferably, it is 200 nm or less, and even more preferably, it is 100 nm or less. The thickness d _LR of the low refractive index layer 16 is set within a predetermined range, either alone or in combination with the thickness d _PR of the primer layer 17, as will be described later.

The average particle diameter r of the inorganic oxide particles depends on the thickness _dLR of the low refractive index layer 16, but is preferably in the range of 60 nm to 400 nm. It is more preferably 70 nm or more, and even more preferably 90 nm or more. It is more preferably 300 nm or less, and even more preferably 200 nm or less. The average particle diameter r of the inorganic oxide particles is a volume-based average arithmetic value obtained by a laser diffraction/scattering method according to JIS Z8825, and includes not only the primary particle diameter but also the secondary particle diameter which is an aggregate of particles.

The content of inorganic oxide particles in the low refractive index layer 16 is preferably 0.1% by mass or more and 4.0% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 16. When the content of inorganic oxide particles in the low refractive index layer 16 is 0.1% by mass or more with respect to 100% by mass of the solid content of the low refractive index layer 16, excellent scratch resistance can be obtained. From this viewpoint, the content of inorganic oxide particles in the low refractive index layer 16 is more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more with respect to 100% by mass of the solid content of the low refractive index layer 16. And, when the content of inorganic oxide particles in the low refractive index layer 16 is 4.0% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 16, high transparency can be obtained. From this viewpoint, the content of inorganic oxide particles in the low refractive index layer 16 is more preferably 3.5% by mass or less, and even more preferably 3.2% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 16. The solid content of the low refractive index layer 16 here refers to components excluding those that are not fixed to the binder resin in the low refractive index layer 16 and are liquid at room temperature. The solid content of the low refractive index layer 16 includes inorganic oxide particles, hollow silica particles, binder resin, etc. It does not include oil components as additives or surfactants that are not fixed to the binder resin.

The hollow silica particles are particles with an average particle diameter smaller than the average thickness of the low refractive index layer 16. The hollow silica particles are preferably particles with an average particle diameter smaller than the inorganic oxide particles that form the convex portions on the surface of the low refractive index layer 16. The hollow silica particles are particles that do not substantially contribute to the formation of the surface unevenness of the low refractive index layer 16. The hollow silica particles are particles that have cavities inside the particles, and the ratio of cavities is 5% or more of the volume. The hollow refers to a shell structure consisting of an outer shell and a cavity inside it, or a porous structure having a large number of cavities. The hollow silica particles can lower the refractive index of the low refractive index layer 16 and reduce light reflection by having a hollow structure. The shape of the hollow silica particles is not particularly limited, but is preferably spherical, spindle-shaped, egg-shaped, flat, cubic, amorphous, etc. Among these, spherical, flat, cubic, etc. are particularly preferable.

In hollow silica particles, the proportion of cavities is preferably 10% or more and 80% or less by volume. If the proportion of cavities is 10% or more by volume, the refractive index can be lowered and light reflection can be reduced. More preferably, it is 20% or more by volume, and even more preferably, it is 30% or more by volume. On the other hand, if the proportion of cavities is 80% or less by volume, it is possible to prevent a decrease in the dispersibility of the hollow silica particles. More preferably, it is 60% or less by volume.

The average particle diameter of the hollow silica particles depends on the thickness of the low refractive index layer 16, but is preferably 5 nm or more and 100 nm or less. It is more preferably 20 nm or more, and even more preferably 40 nm or more. It is more preferably 80 nm or less, and even more preferably 70 nm or less. When the average particle diameter of the hollow silica particles is within these preferred ranges, excellent anti-reflection effect and transparency can be obtained in the low refractive index layer 16. The average particle diameter is a volume-based average arithmetic value obtained by a laser diffraction/scattering method according to JIS Z8825. It includes not only the primary particle diameter but also the secondary particle diameter, which is an aggregate of particles.

The refractive index of the hollow silica particles is preferably in the range of 1.01 to 1.45. More preferably, it is in the range of 1.15 to 1.38, and even more preferably, it is in the range of 1.15 to 1.35. When the refractive index of the hollow silica particles is within this range, an excellent anti-reflection effect can be obtained.

The content of hollow silica particles in the low refractive index layer 16 is preferably 6.0% by mass or more and 49.9% by mass or less, based on 100% by mass of the solid content of the low refractive index layer 16. When the content of hollow silica particles in the low refractive index layer 16 is 6.0% by mass or more, based on 100% by mass of the solid content of the low refractive index layer 16, excellent anti-reflection properties can be obtained. From this viewpoint, the content of hollow silica particles in the low refractive index layer 16 is more preferably 10% by mass or more, even more preferably 12% by mass or more, and particularly preferably 15% by mass or more, based on 100% by mass of the solid content of the low refractive index layer 16. And, when the content of hollow silica particles in the low refractive index layer 16 is 49.9% by mass or less, based on 100% by mass of the solid content of the low refractive index layer 16, the deterioration of scratch resistance is suppressed. From this viewpoint, the content of hollow silica particles in the low refractive index layer 16 is more preferably 45% by mass or less, even more preferably 40% by mass or less, and particularly preferably 25% by mass or less, relative to 100% by mass of the solid content of the low refractive index layer 16.

The total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 16 is preferably 10% by mass or more and 50% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 16. When the total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 16 is 10% by mass or more with respect to 100% by mass of the solid content of the low refractive index layer 16, excellent scratch resistance can be obtained. From this viewpoint, the total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 16 is more preferably 15% by mass or more, and even more preferably 20% by mass or more with respect to 100% by mass of the solid content of the low refractive index layer 16. On the other hand, when the total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 16 is 50% by mass or less with respect to 100% by mass of the solid content of the low refractive index layer 16, the inorganic oxide particles and hollow silica particles can be sufficiently retained in the low refractive index layer 16, and therefore excellent scratch resistance can be obtained. From this viewpoint, the total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 16 is more preferably 45% by mass or less, even more preferably 40% by mass or less, and particularly preferably 30% by mass or less, relative to 100% by mass of the solid content of the low refractive index layer 16.

The thickness d _LR of the low refractive index layer 16 is 46 nm or more. When the thickness is 46 nm or more, the smoothness of the surface of the low refractive index layer 16 is high, and the abrasion resistance of the anti-reflection film 10 can be improved. From this viewpoint, the thickness d _LR of the low refractive index layer 16 is more preferably 47 nm or more, and even more preferably 48 nm or more. Although there is no particular upper limit set for the thickness d _LR of the low refractive index layer 16, from the viewpoint of obtaining a high anti-reflection effect, it is preferably 90 nm or less, more preferably 85 nm or less, and even more preferably 75 nm or less. The thickness d _LR of the low refractive index layer 16 may be obtained as the average thickness of the low refractive index layer 16. When the low refractive index layer 16 contains inorganic oxide particles, the average thickness of the low refractive index layer 16 may be obtained as the average value of the thicknesses of the relatively smooth parts in the parts where no inorganic oxide particles are present in the thickness direction. As will be described later, the thickness d _LR of the low refractive index layer 16 is also determined in terms of the total thickness d _LR +d _PR including the thickness d _PR of the primer layer 17 .

The low refractive index layer 16 can be formed using a composition containing inorganic oxide particles, hollow silica particles, and a binder resin. As described above, the binder resin is preferably one having a reactive group reactive to ultraviolet light (ultraviolet curing resin), such as one containing a (meth)acrylate compound. When the binder resin has a reactive group reactive to ultraviolet light, the scratch resistance of the low refractive index layer 16 is improved, and the scratch resistance of the anti-reflection film 10 is improved. When the binder resin has a reactive group reactive to ultraviolet light, the composition for forming the low refractive index layer 16 preferably further contains a photopolymerization initiator. The composition for forming the low refractive index layer 16 may contain a solvent as necessary. The binder resin of the low refractive index layer 16 may be composed of only an ultraviolet curing resin, or may be composed of a combination of an ultraviolet curing resin and a non-ultraviolet curing resin. As the non-ultraviolet curing resin, the photopolymerization initiator, and the solvent, the chemical species listed above as specific examples of those that can be contained in the composition for forming the hard coat layer 14 can also be suitably applied to the composition for forming the low refractive index layer 16.

The content of the photopolymerization initiator is preferably in the range of 0.1% by mass or more and 10% by mass or less, based on the total solid content of the composition for forming the low refractive index layer 16. More preferably, it is 1% by mass or more and 5% by mass or less.

In addition, the low refractive index layer 16 may contain additives, etc., as necessary. Such additives include dispersants, leveling agents, defoamers, thixotropic agents, antibacterial agents, flame retardants, slip agents, refractive index adjusters, etc.

The low refractive index layer 16 may contain a fluorine-containing compound. Examples of the fluorine-containing compound include (meth)acrylates containing a perfluoroalkyl group, as well as compounds similar to the fluorine-containing (meth)acrylates contained in the antifouling layer 18 described below. When the low refractive index layer 16 contains a fluorine-containing compound, the antifouling properties of the antireflection film 10 are improved. However, in the antireflection film 10 according to this embodiment, the antifouling layer 18 is provided on the low refractive index layer 16, and the antifouling layer 18 exhibits high antifouling properties, so there is no need to include a fluorine-containing compound in the low refractive index layer 16 for the purpose of improving the antifouling properties. If the low refractive index layer 16 contains a large amount of a fluorine-containing compound, the adhesion to the primer layer 17 is weakened, leading to a decrease in the scratch resistance of the antireflection film 10, but by making the low refractive index layer 16 not contain a fluorine-containing compound, the scratch resistance of the antireflection film 10 can be improved. Even if the low refractive index layer 16 contains a fluorine-containing compound, it is advisable to keep the content to 1% by mass or less relative to 100% by mass of the solid content of the low refractive index layer 16.

The refractive index of the low refractive index layer 16 is not particularly limited as long as it is lower than that of the hard coat layer 14, but is preferably 1.35 or more and 1.52 or less. If the refractive index is 1.35 or more, the strength of the low refractive index layer 16 can be made sufficient, and good scratch resistance can be obtained. On the other hand, if the refractive index is 1.52 or less, the anti-reflection film 10 can have a lower reflectance. From the above viewpoints, the refractive index of the low refractive index layer 16 is more preferably 1.38 or more and 1.50 or less, and even more preferably 1.40 or more and 1.49 or less.

(Primer layer)
In the antireflection film 10 according to this embodiment, a primer layer 17 is provided between the low refractive index layer 16 and the antifouling layer 18. The primer layer 17 serves to increase the adhesion between the low refractive index layer 16 and the antifouling layer 18, thereby improving the antifouling properties and abrasion resistance of the antireflection film 10.

The material constituting the primer layer 17 is not particularly limited, but it is preferably made of a cured product of a composition containing a binder resin. In particular, it is preferably made of a cured product of an ionizing radiation curable composition containing a binder resin.

The binder resin is preferably a thermosetting compound or an ionizing radiation curable compound such as an ultraviolet curable compound. From the viewpoint of the productivity of the anti-reflection film 10, it is preferable that the binder resin is made of an ultraviolet curable compound. In particular, it is preferable to use a binder resin that contains a (meth)acrylate compound as the binder resin that constitutes the primer layer 17. As specific examples of (meth)acrylate compounds, those listed above as specific examples of the (meth)acrylate species contained in the binder resin of the low refractive index layer 16 can also be suitably applied to the primer layer 17.

The binder resin contained in the primer layer 17 may or may not contain the same components as the binder resin contained in the low refractive index layer 16. However, if the binder resin contains the same components, the adhesion between the low refractive index layer 16 and the primer layer 17 will be higher, and the anti-reflection film 10 will be more effectively improved in terms of anti-fouling properties and abrasion resistance. Preferably, the binder resin contained in the primer layer 17 is composed of the same binder resin as the binder resin contained in the low refractive index layer 16. Alternatively, the composition of the binder resin contained in the primer layer 17 may be close to that of the binder resin contained in the low refractive index layer 16, such as a form in which 90% by mass or more of the binder resin contained in the primer layer 17 is the same as the binder resin contained in the low refractive index layer 16. Even if the composition of the binder resin contained in the primer layer 17 is the same as or close to the composition of the binder resin contained in the low refractive index layer 16, observation using an electron microscope or the like confirms that a clear interface often exists between the primer layer 17 and the low refractive index layer 16.

It is preferable that the primer layer 17 does not contain particles made of inorganic oxides, such as inorganic oxide particles and hollow silica particles contained in the low refractive index layer 16. It is preferable that the primer layer 17 does not contain solid particles such as resin particles other than particles made of inorganic oxides. By not containing solid particles such as particles made of inorganic oxides, the primer layer 17 has high adhesion to the low refractive index layer 16 and high surface smoothness, and is highly effective in improving the antifouling properties and abrasion resistance of the antireflection film 10. Even if the primer layer 17 contains solid particles, in order to maintain the effects, it is preferable to keep the particle size of the solid particles to 20 nm or less and the content of the solid particles to 10 mass % or less relative to 100 mass % of the solid content of the primer layer 17. The solid content of the primer layer 17 here refers to components in the primer layer 17 that are not fixed to the binder resin and are liquid at room temperature. The solid content of the primer layer 17 includes binder resin and the like.

The primer layer 17 can be formed using a composition containing a binder resin. As described above, the binder resin is preferably one having a reactive group reactive to ultraviolet light (ultraviolet curable resin), such as one containing a (meth)acrylate compound, and in that case, the composition for forming the primer layer 17 preferably further contains a photopolymerization initiator. The composition for forming the primer layer 17 may contain a solvent as necessary. The binder resin of the primer layer 17 may be composed of only an ultraviolet curable resin, or may be composed of a combination of an ultraviolet curable resin and a non-ultraviolet curable resin.

As for the non-UV curable resin, photopolymerization initiator, and solvent, the chemical species given above as specific examples of those that can be contained in the composition for forming the hard coat layer 14 can also be suitably applied to the composition for forming the primer layer 17. The content of the photopolymerization initiator is preferably in the range of 0.1% by mass or more and 20% by mass or less, based on the total solid content of the composition for forming the low refractive index layer 16. More preferably, it is 5% by mass or more and 15% by mass or less.

In addition, the primer layer 17 may contain additives, etc., as necessary. Such additives include dispersants, leveling agents, defoamers, thixotropic agents, antibacterial agents, flame retardants, slip agents, refractive index adjusters, etc.

The thickness d _PR of the primer layer 17 is 8 nm or more. When the thickness is 8 nm or more, the smoothness of the surface of the primer layer 17 is increased, and the abrasion resistance of the anti-reflection film 10 can be improved. From this viewpoint, the thickness d _PR of the primer layer 17 is more preferably 10 nm or more, and even more preferably 14 nm or more. Although there is no particular upper limit set for the thickness d _PR of the primer layer 17, from the viewpoint of obtaining high scratch resistance and anti-reflection effect, it is preferably 55 nm or less, more preferably 50 nm or less, and even more preferably 45 nm or less. The thickness d _PR of the primer layer 17 may be determined as the average thickness of the primer layer 17.

As described above, in the anti-reflection film 10 according to this embodiment, the thickness d _LR of the low refractive index layer 16 is 46 nm or more, and the thickness d _PR of the primer layer 17 is 8 nm or more. Furthermore, the total thickness of the low refractive index layer 16 and the primer layer 17, that is, d _LR +d _PR , is 60 nm or more and 100 nm or less. When the total thickness d _LR +d _PR of the low refractive index layer 16 and the primer layer 17 is 60 nm or more, the anti-reflection film 10 can obtain a high anti-reflection effect and excellent abrasion durability. From the viewpoint of further enhancing these effects, d _LR +d _PR is preferably 60 nm or more, more preferably 62 nm or more, and even more preferably 65 nm or more. On the other hand, when the total thickness d _LR +d _PR of the low refractive index layer 16 and the primer layer 17 is 100 nm or less, the anti-reflection film 10 can obtain a high anti-reflection effect. From the viewpoint of enhancing the effect, d _LR +d _PR is preferably 97 nm or less, more preferably 95 nm or less. As described below, the low refractive index layer 16 and the primer layer 17 preferably have a refractive index close to each other, and can be optically approximated to a single layer. Therefore, by defining the total thickness d _LR +d _PR of the low refractive index layer 16 and the primer layer 17 within an appropriate range, excellent antireflection properties can be obtained. Specifically, by setting the total thickness d _LR +d _PR to 60 nm or more and 100 nm or less as described above, the shift (shift to the long wavelength side and the short wavelength side) between the wavelength at which the reflectance obtained by the light interference effect is the minimum and the relative luminous efficiency peak wavelength for the low refractive index layer 16 and the primer layer 17 as a whole can be suppressed to a small value, and a low luminous reflectance can be obtained.

The primer layer 17 preferably has a smoother surface than the low refractive index layer 16. This improves adhesion between the low refractive index layer 16 and the antifouling layer 18, and the primer layer 17 enhances the effect of enhancing adhesion between the low refractive index layer 16 and the antifouling layer 18. This effectively improves the abrasion resistance of the antireflection film 10. Furthermore, the smooth surface of the primer layer 17 enhances the smoothness of the surface of the antifouling layer 18 formed thereon. This effectively improves the antifouling properties of the antireflection film 10. When the low refractive index layer 16 contains inorganic oxide particles, the primer layer 17 does not contain solid particles, including particles made of inorganic oxides, so that the smoothness of the surface of the primer layer 17 can be easily increased to be greater than that of the low refractive index layer 16.

Before forming the primer layer 17, the surface of the low refractive index layer 16 may be subjected to a surface treatment. Examples of surface treatments include corona treatment, plasma treatment, hot air treatment, ozone treatment, and ultraviolet treatment.

From the viewpoint of obtaining high antireflection properties in the antireflection film 10, it is preferable that the difference between the refractive index of the primer layer 17 and that of the low refractive index layer 16 is small. Specifically, the refractive index of the primer layer 17 is preferably 1.56 or less, more preferably 1.52 or less, and even more preferably 1.50 or less. On the other hand, from the viewpoint of obtaining sufficient strength of the primer layer 17 and good scratch resistance, the refractive index of the primer layer 17 is preferably 1.40 or more, more preferably 1.43 or more, and even more preferably 1.45 or more.

(Anti-stain layer)
In the antireflection film 10 according to this embodiment, an antifouling layer 18 is provided on the surface of the primer layer 17. The antifouling layer 18 enhances the antifouling properties of the antireflection film 10.

The stain-resistant layer 18 is composed of a cured product of a composition containing a fluorine-containing (meth)acrylate. In particular, it is preferable that the antifouling layer 18 is composed of a cured product of an ionizing radiation-curable composition, particularly an ultraviolet-curable composition, containing such a fluorine-containing (meth)acrylate.

The antifouling layer 18 is made of a cured product of a composition containing a fluorine-containing (meth)acrylate, and thus the antireflection film 10 having the antifouling layer 18 on its surface has excellent antifouling properties and abrasion resistance. Specific examples of fluorine-containing (meth)acrylates include (meth)acrylates containing a perfluoropolyether group. The perfluoropolyether group refers to a polyether such as polyethylene glycol or polypropylene glycol in which all hydrogen atoms are replaced with fluorine atoms, and examples thereof include fluoropolyether groups having a repeating structure of any one of perfluoromethylene oxide (-CF ₂ O-), perfluoroethylene oxide (-CF ₂ CF ₂ O-), perfluoropropylene oxide (-CF ₂ CF ₂ CF ₂ O-), and perfluoroisopropylene oxide (-CF(CF ₃ )CF ₂ O-), or a combination of a plurality of these. The number of repeating units of the repeating structure is preferably 1 to 100. Specific examples of the compounds include "KY-1203" and "KY-1207" manufactured by Shin-Etsu Chemical Co., Ltd., "Megafac RS-75" manufactured by DIC, "Optool DAC-HP" manufactured by Daikin Industries, Ltd., and "Ftergent 601AD" and "Ftergent 601ADH2" manufactured by Neos.

Furthermore, it is preferable that the fluorine-containing (meth)acrylate does not have a urethane bond in its structure. When the fluorine-containing (meth)acrylate does not have a urethane bond in its structure, the hardness of the stain-resistant layer 18 is increased, and the stain-resistant layer 18 is provided with particularly high abrasion resistance.

In the antifouling layer 18, the content of the fluorine-containing (meth)acrylate is 90% by mass or more based on the total solid content of the antifouling layer 18. This makes it possible to obtain a high antifouling effect due to the fluorine-containing (meth)acrylate. In the antireflection film 10 according to this embodiment, the primer layer 17 is provided below the antifouling layer 18, so that the effect of improving adhesion to the lower layer and improving the abrasion resistance of the surface can be sufficiently obtained, and therefore, in order to obtain these effects, it is not necessary to add a binder resin that does not contain fluorine, such as a fluorine-free (meth)acrylate compound, to the antifouling layer 18. From the viewpoint of further enhancing the effect of improving the antifouling property, it is more preferable that the content of the fluorine-containing (meth)acrylate in the antifouling layer 18 is 92% by mass or more based on the total solid content of the antifouling layer 18. It is also more preferable that the total amount of the resin components constituting the antifouling layer 18, excluding unavoidable components, is a fluorine-containing (meth)acrylate. The solid content of the antifouling layer 18 here refers to components in the antifouling layer 18 that are not fixed to the curable components and are liquid at room temperature. The solid content of the antifouling layer 18 includes fluorine-containing (meth)acrylates, etc.

The antifouling layer 18 can be formed using a composition containing a fluorinated (meth)acrylate. The composition for forming the antifouling layer 18 can be arranged in the form of a layer on the surface of the primer layer 17 and then cured. When the antifouling layer 18 is formed as a cured product of a composition having ultraviolet curing properties, it is preferable that the composition for forming the antifouling layer 18 further contains a photopolymerization initiator.

As the photopolymerization initiator and the solvent, the chemical species given above as specific examples of those that can be contained in the composition for forming the hard coat layer 14 can also be suitably applied to the composition for forming the antifouling layer 18. The content of the photopolymerization initiator is preferably in the range of 0.1% by mass or more and 15% by mass or less, based on the total solid content of the composition for forming the antifouling layer 18. More preferably, it is 3% by mass or more and 10% by mass or less.

Furthermore, the antifouling layer 18 may contain additives, etc., as necessary. Such additives include antifouling agents other than fluorinated (meth)acrylates, dispersants, leveling agents, defoamers, thixotropic agents, antibacterial agents, flame retardants, slip agents, and refractive index adjusters. However, from the viewpoint of improving the smoothness of the surface of the antifouling layer 18, it is preferable that the antifouling layer 18 does not contain solid particles, including metal acid particles. Even if the antifouling layer 18 contains solid particles, it is preferable that the particle size of the solid particles is kept to 10 nm or less, and the content of the solid particles is kept to 1 mass % or less relative to 100 mass % of the solid content of the antifouling layer 18.

The thickness of the anti-stain layer 18 is preferably 1 nm or more. This allows the anti-stain layer 18 to have a high effect of improving the anti-stain properties. More preferably, the thickness of the anti-stain layer 18 is 3 nm or more, and even more preferably 5 nm or more. On the other hand, the thickness of the anti-stain layer 18 is preferably 15 nm or less. This allows the anti-reflection properties of the anti-reflection film 10 to be maintained at a high level. More preferably, the thickness of the anti-stain layer 18 is 10 nm or less.

The refractive index of the anti-stain layer 18 is preferably 1.6 or less. If it is 1.6 or less, the anti-reflection properties of the anti-reflection film 10 can be maintained at a high level. More preferably, the refractive index of the anti-stain layer 18 is 1.55 or less, and even more preferably 1.50 or less. On the other hand, the lower limit of the refractive index of the anti-stain layer 18 is not particularly limited as long as the thickness of the anti-stain layer 18 is within the above range, but is preferably 1.3 or more, and more preferably 1.35 or more.

From the viewpoint of achieving both scratch resistance and abrasion resistance, the arithmetic mean roughness Ra of the surface of the antifouling layer 18 is preferably in the range of 0.3 nm to 10 nm. More preferably, it is in the range of 0.5 nm to 5 nm, and even more preferably, it is in the range of 1 nm to 3 nm. From the same viewpoint, the average inclination angle θa of the surface of the antifouling layer 18 is preferably in the range of 0.03° to 0.4°, more preferably, 0.05° to 0.3°, and even more preferably, 0.1° to 0.2°.

(Method of manufacturing anti-reflection film)
To manufacture the anti-reflection film 10, the hard coat layer 14, the low refractive index layer 16, the primer layer 17, and the antifouling layer 18 may be formed in this order. To form each layer, a composition for forming each layer may be applied, dried as necessary, and then cured by a method according to the curing property of the composition, such as irradiation with ionizing radiation including ultraviolet rays. After forming a certain layer, a composition for forming the next layer may be applied, dried as necessary, and then cured. By sequentially repeating this process, a laminated structure of the hard coat layer 14, the low refractive index layer 16, the primer layer 17, and the antifouling layer 18 may be formed, and the anti-reflection film 10 may be manufactured.

Wet methods can be suitably used to apply the compositions that form each layer. Specifically, various coating methods such as reverse gravure coating, direct gravure coating, die coating, bar coating, wire bar coating, roll coating, spin coating, dip coating, spray coating, knife coating, and kiss coating, as well as various printing methods such as inkjet printing, offset printing, screen printing, and flexographic printing can be used.

The drying process for each layer is not particularly limited as long as it can remove the solvents used in the coating liquid, but it is preferable to perform the process at a temperature of 50 to 150°C for about 10 to 180 seconds.

For the irradiation of each layer with ultraviolet light, a high pressure mercury lamp, an electrodeless (microwave type) lamp, a xenon lamp, a metal halide lamp, or any other ultraviolet light irradiation device can be used. The ultraviolet light irradiation may be performed under an inert gas atmosphere such as nitrogen, if necessary. The amount of ultraviolet light irradiation is not particularly limited, but is preferably 50 to 800 mJ/ ^cm2 , and more preferably 100 to 300 mJ/ ^cm2 .

When forming the hard coat layer 14 on the surface of the substrate film 12, the surface of the substrate film 12 may be subjected to a surface treatment before coating in order to improve the adhesion between the substrate film 12 and the hard coat layer 14. Examples of surface treatments include corona treatment, plasma treatment, hot air treatment, ozone treatment, and ultraviolet treatment.

(Characteristics of anti-reflective film)
The anti-reflection film 10 having the above configuration has a substrate film 12, a hard coat layer 14 formed on a surface of the substrate film 12, a low refractive index layer 16 formed on the surface of the hard coat layer 14, a primer layer 17 formed on the surface of the low refractive index layer 16, and an antifouling layer 18 formed on the surface of the primer layer 17, wherein the antifouling layer 18 is composed of a cured product of a composition containing a fluorinated (meth)acrylate, the content of the fluorinated (meth)acrylate in the antifouling layer 18 is 90 mass% or more based on the total solids content of the antifouling layer 18, the thickness d _LR of the low refractive index layer is 46 nm or more, the thickness d _PR of the primer layer is 8 nm or more, and the total thickness d _LR +d _PR of the low refractive index layer 16 and the primer layer 17 is 60 nm or more and 100 nm or less. In the antireflection film 10, the antifouling layer 18 has the above-mentioned composition, the primer layer 17 is formed between the low refractive index layer 16 and the antifouling layer 18, and the thicknesses of the low refractive index layer 16 and the primer layer 17 and their total satisfy the above-mentioned ranges, so that the antireflection film 10 has excellent antireflection properties and scratch resistance, as well as high antifouling properties and abrasion resistance.

The high antifouling properties of the antireflection film 10 make it difficult for stains such as fingerprints to adhere to the surface of the antireflection film 10, and even if they do adhere, they can be easily removed. The antireflection film 10 according to this embodiment is particularly excellent in terms of the ease with which fingerprints can be wiped off. In the antireflection film 10 according to this embodiment, the high antifouling properties are thought to be due to the high smoothness of the surface of the antifouling layer 18, which is achieved by the formation of the primer layer 17. In addition, the high wear resistance is thought to be due to the high adhesion between the low refractive index layer 16 and the antifouling layer 18, which is achieved by the presence of the primer layer 17. The antireflection film 10 according to this embodiment has high antireflection properties and antifouling properties, as well as high scratch resistance and wear resistance, and is therefore particularly suitable for applications that are frequently exposed to contact with fingers, such as those placed on the surface of a touch panel.

From the viewpoint of good visibility, the haze of the anti-reflection film 10 is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.0 or less. The lower the luminous reflectance of the anti-reflection film 10, the more preferable, and it is more preferably 2.5% or less, and even more preferably 2.0% or less. If the luminous reflectance is 2.0% or less, the anti-reflection film 10 can be considered to have sufficiently high anti-reflection properties.

<Other forms of anti-reflection film>
As described above, the antireflection film according to the present invention is a film in which the hard coat layer 14, the low refractive index layer 16, the primer layer 17, and the antifouling layer 18 are laminated in this order on the surface of the substrate film 12, and is not limited to the configuration of the antireflection film 10 according to the first embodiment described above as long as the antifouling layer 18 has a predetermined composition and the thicknesses of the low refractive index layer 16 and the antifouling layer 18 and their total fall within predetermined ranges. Other embodiments of the antireflection film according to the present invention will be illustrated below.

Second Embodiment
2 shows an anti-reflection film 20 according to the second embodiment. The anti-reflection film 20 according to the second embodiment has a base film 12, a hard coat layer 14 formed on the surface of the base film 12, a high refractive index layer 15 formed on the surface of the hard coat layer 14, a low refractive index layer 16 formed on the surface of the high refractive index layer 15, a primer layer 17 formed on the surface of the low refractive index layer 16, and an antifouling layer 18 formed on the surface of the primer layer 17.

The anti-reflection film 20 according to the second embodiment differs from the anti-reflection film 10 according to the first embodiment in that it has a high refractive index layer 15 between the hard coat layer 14 and the low refractive index layer 16. Other than this, it is similar to the anti-reflection film 10 according to the first embodiment, and a description of the similar configuration will be omitted.

The high refractive index layer 15 is a layer having a higher refractive index than the hard coat layer 14 and the low refractive index layer 16. By providing the high refractive index layer 15 between the hard coat layer 14 and the low refractive index layer 16, the anti-reflection film 20 exhibits a higher anti-reflection effect. The refractive index of the high refractive index layer 15 is preferably in the range of 1.55 or more and 1.80 or less. More preferably, it is 1.60 or more and 1.70 or less.

The average thickness of the high refractive index layer 15 varies depending on the refractive index setting, but by setting it to, for example, 50 nm or more and 200 nm or less, the anti-reflection function can be further improved. The high refractive index layer 15 may be provided by stacking two or more layers having mutually different refractive indices.

Third Embodiment
3 shows an anti-reflection film 30 according to a third embodiment. The anti-reflection film 30 according to the third embodiment has a base film 12, a hard coat layer 14 formed on one side of the base film 12, a low refractive index layer 16 formed on the surface of the hard coat layer 14, a primer layer 17 formed on the surface of the low refractive index layer 16, and an antifouling layer 18 formed on the surface of the primer layer 17. The base film 12 also has a transparent adhesive layer 22 on the other side. A release film 24 is disposed on the surface of the transparent adhesive layer 22 as necessary. The release film 24 functions as a protective layer for the transparent adhesive layer 22 before use of the anti-reflection film 30, and is peeled off from the transparent adhesive layer 22 when the anti-reflection film 30 is used.

The anti-reflection film 30 according to the third embodiment differs from the anti-reflection film 10 according to the first embodiment in that it has a transparent adhesive layer 22 on the other side of the base film 12. Other than this, it is the same as the anti-reflection film 10 according to the first embodiment, and a description of the similar configuration will be omitted.

The transparent adhesive layer 22 is for attaching the anti-reflection film 30 to the surface of a display or the like with good adhesion. Furthermore, by having the transparent adhesive layer 22, the anti-reflection film 30 has the effect of preventing the glass of a display or the like from shattering. In other words, the anti-reflection film 30 also functions as a shatterproof film.

The adhesive composition forming the transparent adhesive layer 22 can contain known adhesive resins such as acrylic adhesives, silicone adhesives, and urethane adhesives. Among them, acrylic adhesives are preferred from the viewpoint of optical transparency and heat resistance. The adhesive composition preferably contains a crosslinking agent to increase the cohesive strength of the transparent adhesive layer 22. Examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, and chelate crosslinking agents.

The adhesive composition may contain additives as necessary. Examples of additives include known additives such as plasticizers, silane coupling agents, surfactants, antioxidants, fillers, hardening accelerators, and hardening retarders. From the standpoint of productivity, the adhesive composition may be diluted with an organic solvent.

The thickness of the transparent adhesive layer 22 is not particularly limited, but is preferably in the range of 5 μm to 100 μm. More preferably, it is 10 μm or more and 50 μm or less.

The transparent adhesive layer 22 can be formed by a method of directly applying an adhesive composition onto the other side of the base film 12, a method of applying an adhesive composition onto the surface of a release film 24 and then transferring it onto the other side of the base film 12, or a method of applying an adhesive composition onto the surface of a first release film and then laminating a second release film, peeling off one of the release films, and transferring it onto the other side of the base film 12.

From the viewpoint of preventing glass from shattering, it is preferable that the adhesive strength of the transparent adhesive layer 22 to glass is 4 N/25 mm or more. More preferably, it is 6 N/25 mm or more, and even more preferably, it is 10 N/25 mm or more.

(Fourth embodiment)
4 shows an anti-reflection film 40 according to a fourth embodiment. The anti-reflection film 40 according to the fourth embodiment has a base film 12, a hard coat layer 14 formed on one side of the base film 12, a low refractive index layer 16 formed on the surface of the hard coat layer 14, a primer layer 17 formed on the surface of the low refractive index layer 16, an antifouling layer 18 formed on the surface of the primer layer 17, and a protective film 28 arranged on the surface of the antifouling layer 18 via an adhesive layer 26. The base film 12 also has a transparent adhesive layer 22 on the other side. A release film 24 is arranged on the surface of the transparent adhesive layer 22 as necessary.

The anti-reflection film 40 according to the fourth embodiment differs from the anti-reflection film 30 according to the third embodiment in that it has a protective film 28 on the surface of the anti-fouling layer 18 via an adhesive layer 26, but is otherwise similar to the anti-reflection film 30 according to the third embodiment, and a description of the similar configuration will be omitted.

The protective film 28 prevents the surface of the antifouling layer 18 from being scratched when the antireflection film 40 is handled, for example, when it is continuously processed by a roll process or attached to a display or the like. The protective film 28 is attached to the surface of the antifouling layer 18 via the adhesive layer 26. The protective film 28 is peeled off from the surface of the antifouling layer 18 together with the adhesive layer 26 after processing of the antireflection film 40. For this reason, the adhesive layer 26 is adjusted so that the adhesive strength between the protective film 28 and the adhesive layer 26 is stronger than the adhesive strength between the antifouling layer 18 and the adhesive layer 26, and the adhesive strength between the antifouling layer 18 and the adhesive layer 26 is capable of being peeled off at the interface.

The material constituting the protective film 28 can be appropriately selected from the materials exemplified as the material constituting the base film 12. The thickness of the protective film 28 is not particularly limited, but can be in the range of 2 μm to 500 μm, or in the range of 2 μm to 200 μm.

As the adhesive layer 26, the one described in Patent Document 1 can be suitably applied. The adhesive forming the adhesive layer 26 is not particularly limited, and acrylic adhesives, silicone adhesives, urethane adhesives, etc. can be suitably used. In particular, acrylic adhesives are suitable because of their excellent transparency and heat resistance. The acrylic adhesive is preferably formed from an adhesive composition containing a (meth)acrylic polymer and a crosslinking agent.

(Meth)acrylic polymers are homopolymers or copolymers of (meth)acrylic monomers. Examples of (meth)acrylic monomers include alkyl group-containing (meth)acrylic monomers, carboxyl group-containing (meth)acrylic monomers, and hydroxyl group-containing (meth)acrylic monomers.

Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, metal chelate-based crosslinking agents, metal alkoxide-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, and melamine-based crosslinking agents. These crosslinking agents may be used alone or in combination of two or more.

The adhesive composition may contain other additives in addition to the (meth)acrylic polymer and crosslinking agent. Other additives include crosslinking accelerators, crosslinking retarders, tackifier resins, antistatic agents, silane coupling agents, plasticizers, peeling aids, pigments, dyes, wetting agents, thickeners, UV absorbers, preservatives, antioxidants, metal deactivators, alkylating agents, and flame retardants. These are appropriately selected and used depending on the application and purpose of the adhesive.

The thickness of the adhesive layer 26 is not particularly limited, but is preferably in the range of 1 μm to 10 μm. More preferably, it is 2 μm or more and 7 μm or less.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

For example, in the above embodiment, it is described that the surface of the base film 12 may be subjected to a surface treatment, but instead of the surface treatment, an easy-adhesion layer may be provided on the surface of the base film 12.

Also, before each layer is formed, various functional layers such as a gas barrier improving layer, an antistatic layer, and an oligomer block layer may be provided on the surface of the base film 12. As the antistatic layer, the one described in Patent Document 1 can be suitably used.

The transparent adhesive layer 22 and release film 24 in the third embodiment are shown as being added to the anti-reflection film 10 of the first embodiment shown in FIG. 1, as shown in FIG. 3, but may also be added to the anti-reflection film 20 of the second embodiment shown in FIG. 2. The adhesive layer 26 and protective film 28 in the fourth embodiment are shown as being added to the anti-reflection film 30 of the third embodiment shown in FIG. 3, as shown in FIG. 4, but may also be added to the anti-reflection film 10 of the first embodiment shown in FIG. 1 or the anti-reflection film 20 of the second embodiment shown in FIG. 2.

The present invention will be described in detail below using examples and comparative examples. Unless otherwise specified below, sample preparation and evaluation were carried out at room temperature in the atmosphere.

<Preparation of hard coat layer forming composition>
A photopolymerization initiator "Omnirad 127" (manufactured by IGM Resins B.V.) was added to an ultraviolet-curable resin composition "ESS-620" (manufactured by DIC, urethane acrylate resin, solvent (ethyl acetate), solid content concentration 79% by mass) so as to be 3% by mass relative to the total amount of the composition for forming a hard coat layer, and ethyl acetate was added so as to be a solid content concentration of 31% by mass, thereby preparing a composition for forming a hard coat layer.

<Preparation of high refractive index layer forming composition>
A composition for forming a high refractive index layer was prepared by adding methyl ethyl ketone to an ultraviolet-curable resin composition "TYZ65-01" (manufactured by Toyochem, acrylic resin, containing zirconium oxide (average particle size 80 nm), photopolymerization initiator, solvent (cyclohexanone, methyl isobutyl ketone, propylene glycol monomethyl ether), solid content concentration 35% by mass) so that the solid content concentration was 8% by mass.

<Preparation of composition for forming low refractive index layer>
A binder resin, hollow silica particles, alumina particles, a fluorine-containing compound (only Comparative Example 8), and a photopolymerization initiator were blended to obtain the blending composition (mass % of the total solid content) shown in Table 1, and the solid content concentration was adjusted to the solid content concentration shown in Table 1 using a solvent (MEK/PGM = 1/3), to prepare a composition for forming a low refractive index layer.
The materials used for the composition for forming the low refractive index layer are as follows.
Binder resin: "Aronix MT-3041" manufactured by Toagosei, multifunctional acrylate, solid content concentration 100% by mass
Hollow silica particles: "Sururia 4320" manufactured by JGC Catalysts and Chemicals, average particle size 60 nm, solvent (MIBK), solid content concentration: 20% by mass
Alumina particles: Toyochem alumina sol "Lioduras KT-110AL", 25% by mass of alumina particles (average particle size: 110 nm), 15% by mass of photosensitive monomer and resin, solvent (MEK, cyclohexanone, aliphatic solvent)
Fluorine-containing compound: "KY-1216" manufactured by Shin-Etsu Chemical Co., Ltd., perfluoropolyether group-containing (meth)acrylate, solvent (MEK), solid content concentration 20% by mass
Photopolymerization initiator: "Omnirad 127"

<Preparation of primer layer-forming composition>
A binder resin (the above-mentioned "Aronix MT-3041") and a photopolymerization initiator (the above-mentioned "Omnirad 127") were blended so as to obtain the blending composition (mass % of the total solid content) shown in Table 1, and the solid content concentration was adjusted to the solid content concentration shown in Table 1 using a solvent (MEK/PGM=1/3), thereby preparing a composition for forming a primer layer.

<Preparation of Antifouling Layer-Forming Composition>
A fluorine-containing compound (the above "KY-1216"), a binder resin (the above "Aronix MT-3041"; only Comparative Example 7), and a photopolymerization initiator (the above "Omnirad 127") were blended so as to obtain the blending composition (mass % of the total solid content) shown in Table 1, and the solid content concentration was adjusted to the one shown in Table 1 using a solvent (MEK/PGM=1/3), thereby preparing a composition for forming an antifouling layer.

<Preparation of hard coat layer>
For each of Examples 1 to 8 and Comparative Examples 1 to 8, a composition for forming a hard coat layer was applied to a base film (Toray's "Lumirror #50-U403", a polyethylene terephthalate film, thickness 50 μm) using a #12 wire bar, and after drying at 80°C x 60 seconds, a hard coat layer (film thickness 4 μm) was formed by irradiating the composition with ultraviolet light at a light intensity of 200 mJ/ ^cm2 using a high-pressure mercury lamp.

<Preparation of high refractive index layer>
For each of Examples 1 to 8 and Comparative Examples 1 to 8, a composition for forming a high refractive index layer was applied onto the surface of the hard coat layer, and after drying at 80°C for 60 seconds, a high refractive index layer (film thickness 110 nm) was formed by irradiating ultraviolet light at a light intensity of 200 mJ/ ^cm2 using a high pressure mercury lamp under a nitrogen atmosphere.

<Preparation of low refractive index layer>
For each of Examples 1 to 8 and Comparative Examples 1 to 8, a composition for forming a low refractive index layer was applied onto the surface of the high refractive index layer using a #3 wire bar, and after drying at 100°C for 60 seconds, a low refractive index layer was formed by irradiating ultraviolet light with a light amount of 200 mJ/ ^cm2 using a high pressure mercury lamp in a nitrogen atmosphere. The film thickness was as shown in Table 1.

<Preparation of primer layer>
For each of Examples 1 to 8 and Comparative Examples 1 to 5, a primer layer-forming composition was applied onto the surface of the low refractive index layer using a #3 wire bar, and after drying at 100°C for 60 seconds, a primer layer was formed by irradiating ultraviolet light at a light intensity of 200 mJ/ ^cm2 using a high-pressure mercury lamp in a nitrogen atmosphere. The film thickness was as shown in Table 1. For Comparative Examples 6 to 8, a primer layer was not formed.

<Preparation of Antifouling Layer>
In Examples 1 to 8 and Comparative Examples 1 to 5, the composition for forming an antifouling layer was applied to the surface of the primer layer, and in Comparative Examples 6 and 7, the composition for forming an antifouling layer was applied to the surface of the low refractive index layer using a #3 wire bar, and after drying at 100°C for 60 seconds, an antifouling layer was formed by irradiating ultraviolet light at a light intensity of 200 mJ/ ^cm2 using a high-pressure mercury lamp in a nitrogen atmosphere. The film thickness was as shown in Table 1. In Comparative Example 8, no antifouling layer was formed.
As described above, anti-reflection films according to Examples 1 to 8 and Comparative Examples 1 to 8 were prepared.

<Evaluation method>
(Thickness and refractive index of each layer)
The thickness and refractive index of each of the hard coat layer, high refractive index layer, low refractive index layer, primer layer, and antifouling layer were evaluated for each sample. Each time each layer was formed, the thickness and refractive index of each layer at a wavelength of 589.3 nm were calculated by curve fitting the reflection spectrum in the wavelength range of 380 to 780 nm obtained using a microspectrophotometer (Otsuka Electronics'"OPTM-F1") to a theoretical spectrum derived based on the Fresnel equation using the least squares method.

(Luminous reflectance)
The back surface of the anti-reflection film thus produced (the surface opposite to the low refractive index layer) was roughened with #400 sandpaper and painted over with black paint. Then, using an ultraviolet-visible-near infrared spectrophotometer (Shimadzu Corporation's "UV-3600"), the 5° regular reflectance of the surface of the low refractive index layer at wavelengths of 380 nm to 780 nm was measured, and the measured value was multiplied by the relative luminous efficiency value to calculate the luminous reflectance. If the luminous reflectance is 2.0% or less, the anti-reflection properties can be considered sufficient.

(Wear resistance)
The abrasion resistance of each sample was evaluated by an eraser abrasion test using the water contact angle as an index.
An eraser abrasion test was performed on each sample. In this case, a flat surface abrasion tester (Daiei Scientific Instruments & Associates, "DAS-400") was used, and an eraser for the eraser abrasion test (Minoan, cylindrical with a contact surface of φ6 mm in diameter) was placed on the surface of the anti-reflective film of each sample and reciprocated. The stroke length of the test stand was 50 mm, the test stand reciprocation speed was 30 reciprocations/min, and the applied load was 1.0 kg. The water contact angle was measured every 100 reciprocations up to 500 reciprocations, and every 500 reciprocations after 500 reciprocations when the number of reciprocations exceeded 500, and the maximum number of reciprocations that maintained a water contact angle of 90° or more was used as the evaluation value. If the evaluation value was 2000 times or more, it can be considered that the sample had sufficient abrasion durability. Furthermore, if the evaluation value was 3000 times or more, it can be considered that the sample had high abrasion durability. The water contact angle was measured by dropping 4 μL of pure water onto the surface of the anti-reflective film using a contact angle meter (DropMaster DMo-502, Kyowa Interface Science).

(Scratch resistance)
A steel wool resistance test was carried out for each sample. In this case, a flat surface abrasion tester (Daiei Scientific Instruments Manufacturing Co., Ltd. "DAS-400") was used, and steel wool #0000 (manufactured by Nippon Steel Wool Co., Ltd.) fixed to a flat surface frictional element of 20 mm x 20 mm was placed on the surface of the anti-reflective film of each sample and reciprocated. The stroke length of the test table was 50 mm, the test table reciprocation speed was 60 reciprocations/min, and the applied load was 1.5 kg, and the anti-reflective film was reciprocated 100 times. Anti-reflective films with scratches of 10 mm or more in length after the test were evaluated as having low scratch resistance (x). In addition, anti-reflective films with scratches of less than 10 mm in length but no scratches of 10 mm or more in length were evaluated as having high scratch resistance (◯). Scratches of this degree do not pose a practical problem. Furthermore, those without scratches were evaluated as having very high scratch resistance (◎).

(Anti-stain properties)
For each sample, the ability to wipe off fingerprints was evaluated as an evaluation of the antifouling properties.
A commercially available artificial fingerprint liquid (manufactured by Isekyu, artificial sweat A method (sweat tester method)) was applied to the fingers, and the fingers were pressed against the surface of the anti-reflective film to leave a fingerprint. The anti-reflective film was then placed on black paper, and the fingerprints left on the surface of the anti-reflective film were wiped off with a polyester wiper (manufactured by AS ONE, ASPURE SUPER WIPER (ECONO)) while observing with the naked eye. Films that could be wiped off to the point where the artificial fingerprint liquid was no longer visible within 10 strokes were evaluated as having high anti-soiling properties (◯), and films that could not be wiped off even after 10 strokes were evaluated as having low anti-soiling properties (×).

<Evaluation Results>
Table 1 shows the evaluation results for Examples 1 to 8 and Comparative Examples 1 to 8, together with the component compositions (unit: mass % of the total solid content of each layer) of the low refractive index layer, primer layer, and antifouling layer, and the layer configurations of the antireflection films.

As shown in Table 1, in Examples 1 to 8, an antifouling layer containing 90% by mass or more of fluorine-containing (meth)acrylate based on the total solid content is formed on the surface of the low refractive index layer with a primer layer sandwiched therebetween. Furthermore, the thickness d _LR of the low refractive index layer is 46 nm or more, the thickness d _PR of the primer layer is 8 nm or more, and the total thickness d _LR +d _PR of the low refractive index layer and the primer layer is 60 nm or more and 100 nm or less. Correspondingly, in all of Examples 1 to 8, a low luminous reflectance of 2.0% or less and a high abrasion durability of 2000 times or more are obtained. At the same time, a high scratch resistance rated as "◎" or "○" is obtained, and a high antifouling property rated as "○" is also obtained.

On the other hand, in Comparative Examples 1 to 3, the total thickness d _LR +d _PR of the low refractive index layer and the primer layer is outside the range of 60 nm to 100 nm, so that the reflection reduction effect due to the light interference effect cannot be sufficiently obtained, and the luminous reflectance exceeds 2.0%. Furthermore, in Comparative Example 1, the thickness d _LR of the low refractive index layer is less than 46 nm, so that the abrasion resistance is low.

In Comparative Example 4, a primer layer having a thickness _dPR of 8 nm or more is provided together with the low refractive index layer, and the total thickness _dLR + _dPR is also 60 nm or more, but the thickness _dLR of the low refractive index layer is less than 46 nm. In this Comparative Example 4, the abrasion resistance is low, which indicates that when the low refractive index layer is too thin, sufficient abrasion resistance cannot be obtained in the antireflection film.

In Comparative Example 6, in which a primer layer was not formed and an antifouling layer was formed directly on the surface of the low refractive index layer, both the abrasion resistance and the antifouling properties were low. The abrasion resistance was significantly lower than in Example 3, which differed only in the presence or absence of a primer layer. It is believed that the lack of a primer layer reduces the adhesion between the low refractive index layer and the antifouling layer, resulting in low abrasion resistance. In addition, the lack of a primer layer reduces the smoothness of the surface of the antifouling layer, and it is believed that sufficient antifouling properties cannot be obtained.

In Comparative Example 5, a primer layer was formed, but its thickness _dPR was less than 8 nm, resulting in low abrasion resistance. This shows that if the primer layer is too thin, the effect of improving the abrasion resistance due to the improved adhesion of the antifouling layer is not fully exerted.

In Comparative Example 7, like Comparative Example 6, no primer layer is provided, but instead a fluorine-free binder resin is added to the anti-stain layer. However, in Comparative Example 7, the abrasion resistance is low. Similarly to Comparative Example 6, the anti-stain properties are also poor, rated as "x". From these results, it can be said that even if a fluorine-free binder resin is added to the anti-stain layer, it cannot function to sufficiently increase the adhesion with the low refractive index layer in place of the primer layer. It can also be interpreted that sufficient anti-stain properties are not obtained due to the relatively low content of fluorine-containing compounds in the anti-stain layer.

In Comparative Example 8, neither a primer layer nor an antifouling layer is provided on the surface of the low refractive index layer. Instead, a fluorine-containing compound is added to the low refractive index layer. However, in Comparative Example 8, both the abrasion resistance and the antifouling properties are poor. This shows that even if a fluorine-containing compound is added to the low refractive index layer instead of providing an antifouling layer, it is not possible to obtain the same effect as an antifouling layer provided as an independent layer on the surface of the low refractive index layer.

As described above, the antireflection film has a substrate film, a hard coat layer formed on the surface of the substrate film, a low refractive index layer formed on the surface of the hard coat layer, a primer layer formed on the surface of the low refractive index layer, and an antifouling layer formed on the surface of the primer layer, the antifouling layer being composed of a cured product of a composition containing a fluorine-containing (meth)acrylate, the content of the fluorine-containing (meth)acrylate in the antifouling layer being 90 mass% or more based on the total solid content of the antifouling layer, the thickness d _LR of the low refractive index layer being 46 nm or more, the thickness d _PR of the primer layer being 8 nm or more, and the total thickness d _LR +d _PR of the low refractive index layer and the primer layer being 60 nm or more and 100 nm or less, and therefore the antireflection film has excellent antireflection properties and scratch resistance, as well as high antifouling properties and abrasion resistance.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention.

REFERENCE SIGNS LIST 10, 20, 30, 40 Anti-reflection film 12 Base film 14 Hard coat layer 15 High refractive index layer 16 Low refractive index layer 17 Primer layer 18 Antifouling layer 22 Transparent adhesive layer 24 Release film 26 Adhesive layer 28 Protective film

Claims (4)

a substrate film, a hard coat layer formed on a surface of the substrate film, a low refractive index layer formed on the surface of the hard coat layer, a primer layer formed on the surface of the low refractive index layer, and an antifouling layer formed on the surface of the primer layer;
the antifouling layer is composed of a cured product of a composition containing a fluorinated (meth)acrylate,
the content of the fluorinated (meth)acrylate in the antifouling layer is 90 mass% or more based on the total solid content of the antifouling layer,
The thickness d _LR of the low refractive index layer is 46 nm or more,
The thickness d _PR of the primer layer is 8 nm or more;
The antireflection film, wherein a total thickness d _LR +d _PR of the low refractive index layer and the primer layer is 60 nm or more and 100 nm or less. the low refractive index layer is composed of a cured product of a composition including a binder resin containing a (meth)acrylate compound, inorganic oxide particles, and hollow silica particles;
2. The anti-reflection film according to claim 1, wherein the primer layer is composed of a cured product of a composition that contains a binder resin including a (meth)acrylate compound and does not contain particles made of an inorganic oxide. The anti-reflection film according to claim 2, wherein the binder resin contained in the primer layer is the same as the binder resin contained in the low refractive index layer. An anti-reflection film according to claim 2 or claim 3, wherein the low refractive index layer does not contain a fluorine-containing compound.

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