Anti-reflective film

Abstract

To provide an antireflection film which has excellent scratch resistance by contribution of a high refractive index layer.SOLUTION: An antireflection film has a base material film, a hard coat layer formed on a surface of the base material film, a high refractive index layer formed on a surface of the hard coat layer, and a low refractive index layer formed on a surface of the high refractive index layer, wherein the high refractive index layer is composed of a cured product of an ionizing radiation-curable composition containing a binder resin and metal oxide particles, the binder resin contains 10 mass% or more and 35 mass% or less of a (meth)acrylate compound having an isocyanuric acid skeleton together with a (meth)acrylate compound having no isocyanuric acid skeleton, in 100 mass% of a solid content of the binder resin.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an antireflection film, and more particularly to an antireflection film suitably used on the surface of displays such as touch panels of liquid crystal displays, organic EL displays, smartphones, etc.

Background Art

[0002] An antireflection film may be disposed on the surface of displays such as touch panels of liquid crystal displays, organic EL displays, smartphones, etc. for the purpose of preventing external light from reflecting onto the screen.

[0003] As an antireflection film, a film having a hard coat layer and an antireflection layer (low refractive index layer) in this order on a base film is known. For example, in Patent Document 1 based on the applicant's application, by examining the composition of the low refractive index layer formed on the surface of the hard coat layer, the antireflection property, scratch resistance, and antifouling property of the antireflection film are improved

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In anti-reflective films, it is effective to improve scratch resistance by modifying the constituent materials of the low refractive index layer formed on the surface of the hard coat layer, as in the embodiment of Patent Document 1. However, in anti-reflective films, a high refractive index layer is often provided below the low refractive index layer, and in such cases, modifying the constituent materials of the high refractive index layer is also considered effective in improving the scratch resistance of the anti-reflective film. If the high refractive index layer is also composed of materials that are effective in improving scratch resistance, it may be possible to effectively improve the scratch resistance of the anti-reflective film as a whole.

[0006] The problem that this invention aims to solve is to provide an anti-reflective film that has excellent scratch resistance due to the contribution of a high refractive index layer. [Means for solving the problem]

[0007] To solve the above problems, the anti-reflective film according to the present invention has the following configuration. [1] The anti-reflective film according to the present invention comprises a base film, a hard coat layer formed on the surface of the base film, a high refractive index layer formed on the surface of the hard coat layer, and a low refractive index layer formed on the surface of the high refractive index layer, wherein the high refractive index layer is composed of a cured product of an ionizing radiation curable composition containing a binder resin and metal oxide particles, and the binder resin contains, together with a (meth)acrylate compound that does not have an isocyanuric acid skeleton, 10% by mass or more and 35% by mass or less of the solid content of the binder resin.

[0008] [2] In the embodiment of [1] above, the (meth)acrylate compound having an isocyanuric acid skeleton may contain 60% by mass or more of a trifunctional (meth)acrylate compound having an isocyanuric acid skeleton, based on 100% by mass of the solid content of the (meth)acrylate compound having an isocyanuric acid skeleton.

[0009] [3] In the embodiment of [1] or [2] above, the metal oxide particles may be titanium oxide particles.

[0010] [4] In any one embodiment of [1] to [3] above, the high refractive index layer consists of one layer and has a refractive index of 1.60 or more and 2.00 or less.

[0011] [5] In any one embodiment of [1] to [3] above, the high refractive index layer consists of two layers, wherein the refractive index of the layer located on the low refractive index layer side of the high refractive index layer is 1.60 or more and 2.00 or less, and the refractive index of the layer located on the hard coat layer side is 1.56 or more and 1.85 or less. [Effects of the Invention]

[0012] The anti-reflective film according to the present invention having the configuration described in [1] above comprises a base film, a hard coat layer formed on the surface of the base film, a high refractive index layer formed on the surface of the hard coat layer, and a low refractive index layer formed on the surface of the high refractive index layer. The high refractive index layer is composed of a cured product of an ionizing radiation curable composition containing a binder resin and metal oxide particles. The binder resin contains a (meth)acrylate compound having an isocyanuric acid skeleton, along with a (meth)acrylate compound without an isocyanuric acid skeleton, in an amount of 10% to 35% by mass of the solid content of the binder resin, thereby providing excellent scratch resistance due to the contribution of the high refractive index layer.

[0013] In the embodiment described in [2] above, the isocyanuric acid skeleton-having (meth)acrylate compound contains 60% by mass or more of a trifunctional (meth)acrylate compound having an isocyanuric acid skeleton, based on 100% by mass of the solid content of the isocyanuric acid skeleton-having (meth)acrylate compound, thereby providing a high degree of improved scratch resistance in the high refractive index layer.

[0014] In the embodiment described in [3] above, the metal oxide particles are titanium oxide particles, which results in a high refractive index layer that is excellent in achieving both a high refractive index and transparency.

[0015] In the aspect of [4] above, since the high refractive index layer consists of one layer and the refractive index is 1.60 or more and 2.00 or less, in the antireflection film, it is possible to highly achieve both improvement in scratch resistance and reduction in reflectance.

[0016] In the aspect of [5] above, since the high refractive index layer consists of two layers, and among the two layers, the refractive index of the layer located on the low refractive index layer side of the high refractive index layer is 1.60 or more and 2.00 or less, and the refractive index of the layer located on the hard coat layer side is 1.56 or more and 1.85 or less, in the antireflection film, it is possible to highly achieve both improvement in scratch resistance and reduction in reflectance. Furthermore, the productivity of the high refractive index layer is increased.

Brief Description of the Drawings

[0017] [Figure 1] It is a cross-sectional view of the antireflection film according to the first embodiment of the present invention. [Figure 2] It is a cross-sectional view of the antireflection film according to the second embodiment of the present invention. [Figure 3] It is a cross-sectional view of the antireflection film according to the third embodiment of the present invention.

Modes for Carrying Out the Invention

[0018] Hereinafter, the present invention will be described in detail. In this specification, unless otherwise specified, various physical properties refer to values at room temperature and in the atmosphere.

[0019] <Antireflection Film of the First Embodiment> FIG. 1 is a cross-sectional view of an antireflection film according to a first embodiment of the present invention. As shown in FIG. 1, the antireflection film 10 according to the first embodiment of the present invention includes a base film 12, a hard coat layer 14 formed on the surface of the base film 12, a high refractive index layer 16 formed on the surface of the hard coat layer 14, and a low refractive index layer 18 formed on the surface of the high refractive index layer 16. The antireflection film 10 has the base film 12, the hard coat layer 14, the high refractive index layer 16, and the low refractive index layer 18 in this order. Preferably, the high refractive index layer 16 and the low refractive index layer 18 are in direct contact without intervening other layers. In the present embodiment, the hard coat layer 14 and the high refractive index layer 16 are also in direct contact without intervening other layers.

[0020] (Base film) The base film 12 is not particularly limited in terms of constituent materials, thickness, etc., as long as it has transparency. As the base film 12, the same ones as those used in Patent Document 1 can be preferably used as follows.

[0021] Examples of the base film 12 include a transparent polymer film and a glass film. Transparency means that the total light transmittance in the visible light wavelength region is 50% or more, 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 or more and 500 μm or less from the viewpoint of excellent handleability. More preferably, it is in the range of 2 μm or more and 200 μm or less. Note that the term "film" generally refers to a film having a thickness of less than 0.25 mm, but even a film having a thickness of 0.25 mm or more is included in the "film" as long as it can be wound in a roll.

[0022] Examples of polymer materials for the base film 12 include polyester resins such as polyethylene terephthalate resin and polyethylene naphthalate resin, polycarbonate resin, poly(meth)acrylate resin, polystyrene resin, polyamide resin, polyimide resin, polyacrylonitrile resin, polyolefin resins such as polypropylene resin, polyethylene resin, polycycloolefin resin, and cycloolefin copolymer resin, cellulose-based resins such as triacetylcellulose resin and diacetylcellulose resin, polyphenylene sulfide resin, polyvinyl chloride resin, polyvinylidene chloride resin, and polyvinyl alcohol resin. The polymer material for the base film 12 may consist of only one of these, or a combination of two or more. Of these, polyethylene terephthalate resin, polyimide resin, polycarbonate resin, poly(meth)acrylate resin, polycycloolefin resin, cycloolefin copolymer resin, and triacetylcellulose resin are more preferred from the viewpoint of optical properties and durability. The base film 12 may consist of a single layer comprising a layer containing one or more of the above-mentioned polymer materials, or it may consist of two or more layers, such as a layer containing one or more of the above-mentioned polymer materials and a layer containing one or more of a different polymer material.

[0023] (Hard coat layer) The hard coat layer 14 contributes to improving the scratch resistance of the anti-reflective film 10. The hard coat layer 14 can preferably be the same as that used in Patent Document 1. Its structure is briefly described below.

[0024] The hard coat layer 14 contributes to improving the scratch resistance of the anti-reflective 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. Ionizing radiation refers to electromagnetic waves or charged particle beams that have energy quanta capable of polymerizing or crosslinking molecules. Examples of ionizing radiation include electromagnetic waves such as ultraviolet rays (UV), X-rays, and gamma rays, and charged particle beams such as electron beams (EB), alpha rays, and ion beams. Of these, ultraviolet rays (UV) are particularly preferred from the viewpoint of productivity of the anti-reflective film 10. Hereinafter, the ionizing radiation-curable composition may simply be referred to as the curable composition. 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." A "(meth)acrylate compound" is a compound having a (meth)acryloyl group, and examples include monomers, oligomers, and prepolymers. Hereinafter, (meth)acrylate compounds may be simply referred to as (meth)acrylate.

[0025] The (meth)acrylate may be monofunctional (meth)acrylate or polyfunctional (meth)acrylate. Alternatively, it may be a combination of monofunctional (meth)acrylate and polyfunctional (meth)acrylate. The curable composition is more preferably polyfunctional (meth)acrylate as the (meth)acrylate, from the viewpoint of improving curability.

[0026] Examples of (meth)acrylates include urethane (meth)acrylate, silicone (meth)acrylate, alkyl (meth)acrylate, and aryl (meth)acrylate. Of these, urethane (meth)acrylate, particularly urethane (meth)acrylate oligomers, are preferred. When the curable composition for forming the hard coat layer 14 contains urethane (meth)acrylate as an ultraviolet-curable resin, the hard coat layer 14 has appropriate flexibility, which increases the bending resistance of the anti-reflective film 10, making it suitable for use in flexible displays that are repeatedly bent, such as foldable displays and rollable displays. Furthermore, even if the base film 12 is formed from, for example, polycycloolefin or cycloolefin copolymer and is relatively brittle, cracking of the base film 12 is easily suppressed.

[0027] It is preferable that the curable composition further contains a pentaerythritol (meth)acrylate compound as the (meth)acrylate. 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, tripentaerythritol octa(meth)acrylate, and the like. In particular, it is preferable that the curable composition contains pentaerythritol tri(meth)acrylate.

[0028] The curable composition forming the hard coat layer 14 may or may not contain a non-UV curable resin in addition to a UV-curable resin. Furthermore, the curable composition forming the hard coat layer 14 may contain a photopolymerization initiator. Additionally, generally available additives may be included as needed. Examples of additives include dispersants, leveling agents, defoamers, vibration modifiers, antifouling agents, antibacterial agents, flame retardants, slip agents, antistatic agents, metal oxide particles, and resin particles. Additionally, solvents may be included as needed.

[0029] Non-UV curable resin, photopolymerization initiator, metal oxide particles, and solvents used in the curable composition for forming the hard coat layer 14 can be the same as those listed later as materials for forming the high refractive index layer 16. Examples of resin particles include (meth)acrylic resin, styrene resin, styrene-(meth)acrylic resin, urethane resin, polyamide resin, silicone resin, epoxy resin, phenolic resin, polyethylene resin, and cellulose.

[0030] The thickness of the hard coat layer 14 is not particularly limited, but is preferably 0.5 μm or more from the viewpoint of having sufficient hardness. More preferably 0.75 μm or more. Furthermore, it is preferably 20 μm or less from the viewpoint of easily suppressing curl caused by the difference in thermal shrinkage with the base film 12. More preferably 10 μm or less. The thickness of the hard coat layer 14 is the thickness of the relatively smooth portion in the thickness direction where there are no irregularities caused by metal oxide particles or resin particles.

[0031] From the viewpoint of suppressing interference unevenness arising from the difference in refractive index between the base film 12 and the hard coat layer 14, the refractive index of the hard coat layer 14 is preferably in the range of 1.49 to 1.56. The arithmetic mean roughness Ra of the surface on which the surface irregularities of the hard coat layer 14 are formed is preferably in the range of 0.3 nm to 20 nm from the viewpoint of suppressing blocking, etc. More preferably it is 0.5 nm or more, and also 10 nm or less.

[0032] (High refractive index layer) In the anti-reflective film 10 according to this embodiment, a high refractive index layer 16 is provided on the surface of the hard coat layer 14. The high refractive index layer 16 is a layer having a higher refractive index than the hard coat layer 14 and the low refractive index layer 18. By providing the high refractive index layer 16 between the hard coat layer 14 and the low refractive index layer 18, the anti-reflective film 10 exhibits a high anti-reflective effect.

[0033] The high refractive index layer 16 is composed of a cured product of an ionizing radiation-curable composition containing a binder resin and metal oxide particles, wherein the binder resin contains a (meth)acrylate compound without an isocyanuric acid skeleton and a (meth)acrylate compound having an isocyanuric acid skeleton. As described above for the hard coat layer 14, ionizing radiation includes various electromagnetic waves and charged particle beams, but it is particularly preferable that the binder resin is ultraviolet (UV) curable.

[0034] The binder resin constituting the high refractive index layer 16 contains a (meth)acrylate compound that does not have an isocyanuric acid skeleton, thereby achieving high hardness in the high refractive index layer 16 and improving the scratch resistance of the anti-reflective film 10. Hereinafter, when the constituent components of the high refractive index layer 16 are simply referred to as (meth)acrylate, it refers to (meth)acrylate that does not have an isocyanuric acid skeleton.

[0035] Examples of (meth)acrylates include urethane (meth)acrylate, silicone (meth)acrylate, alkyl (meth)acrylate, and aryl (meth)acrylate. The (meth)acrylate may consist only of monofunctional (meth)acrylate, or it may consist of polyfunctional (meth)acrylate, or it may consist of a combination of monofunctional (meth)acrylate and polyfunctional (meth)acrylate. It is more preferable for the (meth)acrylate to include polyfunctional (meth)acrylate.

[0036] Examples of 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, and 2-ethylhexyl (meth)acrylate. Nonyl (meth)acrylate, decyl (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, di Cyclopentanyl (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, 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,Examples include ethoxyethyl (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate.

[0037] Examples of polyfunctional (meth)acrylates include difunctional (meth)acrylates, trifunctional (meth)acrylates, and tetrafunctional (meth)acrylates. More specifically, these include 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. Examples 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.

[0038] The (meth)acrylate may consist of one type alone or two or more types. From the viewpoint of improving scratch resistance, the binder resin preferably contains a polyfunctional (meth)acrylate with five or more functions, and it is also preferable to increase the content of the polyfunctional (meth)acrylate with five or more functions.

[0039] Furthermore, it is preferable that the polyfunctional (meth)acrylate contains a dimer. Dimers of polyfunctional (meth)acrylates have excellent curing speed and can easily increase the curing rate of the curable composition, thereby further improving scratch resistance. In particular, it is preferable to include 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 include at least one selected from the group consisting of dimers of pentaerythritol triacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

[0040] From the viewpoint of scratch resistance, the content of the above-mentioned dimer is preferably 25% by mass or more, based on the total solid content of the polyfunctional (meth)acrylate. More preferably 30% by mass or more. On the other hand, from the viewpoint of transparency and solubility in solvents, the content of the dimer is preferably 50% by mass or less, based on the total solid content of the polyfunctional (meth)acrylate. More preferably 40% by mass or less.

[0041] The binder resin contains a (meth)acrylate compound having an isocyanuric acid skeleton, in addition to the (meth)acrylate compound. By using the (meth)acrylate compound having an isocyanuric acid skeleton together with the (meth)acrylate compound, the scratch resistance of the anti-reflective film 10 is improved. This is presumed to be due to the fact that the (meth)acrylate compound having an isocyanuric acid skeleton has the property of being less prone to curing shrinkage. In the high refractive index layer 16, the (meth)acrylate compound having an isocyanuric acid skeleton forms a bond with the (meth)acrylate compound. In the high refractive index layer 16, due to the property of the (meth)acrylate compound having an isocyanuric acid skeleton being less prone to curing shrinkage, internal stress generated between the high refractive index layer 16 and adjacent layers (low refractive index layer 18, hard coat layer 14) can be suppressed, and it is presumed that delamination is less likely to occur when an external force is applied to the anti-reflective film 10, thus improving scratch resistance.

[0042] Examples of (meth)acrylate compounds having an isocyanuric acid skeleton include tris(2-hydroxyethyl)isocyanurate diacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate, ε-caprolactone-modified bis(2-acryloxyethyl)isocyanurate, and ε-caprolactone-modified tris(2-acryloxyethyl)isocyanurate. The curable composition may contain only one of these isocyanurate compounds or two or more.

[0043] The content of the (meth)acrylate compound having an isocyanuric acid skeleton in the high refractive index layer 16 should be 10% by mass or more, preferably 12% by mass or more, and more preferably 13% by mass or more, based on the total solid content of the binder resin (out of 100% by mass of solid content). This allows for a high degree of improvement in scratch resistance due to the (meth)acrylate compound having an isocyanuric acid skeleton. On the other hand, the content should be 35% by mass or less, preferably 33% by mass or less, and more preferably 30% by mass or less. This makes it easier to ensure the hardness of the high refractive index layer 16. Since the (meth)acrylate compound and the (meth)acrylate compound having an isocyanuric acid skeleton each contribute to improving the scratch resistance of the high refractive index layer 16 through different mechanisms, it becomes difficult to obtain a high degree of improvement in scratch resistance if the content of the (meth)acrylate compound having an isocyanuric acid skeleton is too high or too low compared to these ranges. The solid components of the high refractive index layer 16 referred to here are components that are not immobilized in the high refractive index layer 16 and are liquid at room temperature, excluding those components. The solid components of the high refractive index layer 16 include (meth)acrylate compounds, (meth)acrylate compounds containing an isocyanuric acid skeleton, and metal oxide particles. Solvents are not included.

[0044] Furthermore, the (meth)acrylate compound having an isocyanuric acid skeleton preferably includes a trifunctional (meth)acrylate compound having an isocyanuric acid skeleton, from the viewpoint of increasing the degree of crosslinking and achieving high hardness. Among the (meth)acrylate compounds having an isocyanuric acid skeleton listed above, the trifunctional ones are tris(2-hydroxyethyl) isocyanurate triacrylate and ε-caprolactone-modified tris(2-acryloxyethyl) isocyanurate. In particular, the content of the trifunctional (meth)acrylate having an isocyanuric acid skeleton is preferably 8% by mass or more, more preferably 10% by mass or more, and even more preferably 11% by mass or more, based on the total solid content of the binder resin. Furthermore, the content of the trifunctional (meth)acrylate having an isocyanuric acid skeleton is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 85% by mass or more, based on 100% by mass of the (meth)acrylate compound having an isocyanuric acid skeleton. When a trifunctional (meth)acrylate compound having an isocyanuric acid skeleton is used in these proportions, a significant improvement in scratch resistance can be obtained. There is no particular upper limit set for the proportion of the trifunctional (meth)acrylate having an isocyanuric acid skeleton in the total mass of the (meth)acrylate compound having an isocyanuric acid skeleton. This is because a higher proportion results in a greater improvement in the scratch resistance of the high refractive index layer 16 due to increased hardness.

[0045] As described above, the high refractive index layer 16 contains metal oxide particles in addition to the binder resin. The inclusion of metal oxide particles increases the refractive index of the high refractive index layer 16, thereby further enhancing the anti-reflective function of the anti-reflective film 10 when the low refractive index layer 18 is laminated on top of it. A high refractive index means that the refractive index at a measurement wavelength of 589.3 nm is 1.50 or higher, and the refractive index of the high refractive index layer 16 is preferably in the range of 1.60 to 2.00, more preferably in the range of 1.65 to 1.98, and even more preferably in the range of 1.70 to 1.95. In this specification, unless otherwise specified, the refractive index of a substance and a substance layer refers to the value at a measurement wavelength of 589.3 nm.

[0046] Examples of metal oxide particles include those made from oxides of metals such as titanium, zirconium, tin, zinc, silicon, niobium, aluminum, chromium, magnesium, germanium, gallium, antimony, and platinum. These may be used individually or in combination of two or more as optically adjustable metal oxide particles. Among these, titanium oxide and zirconium oxide are particularly preferred from the viewpoint of achieving both high refractive index and transparency. The metal oxide particles may be surface-treated with a surface treatment agent such as a silane coupling agent. In this case, it is preferable that the surface treatment agent has a functional group capable of bonding with (meth)acrylate compounds and (meth)acrylate compounds having an isocyanuric acid skeleton, such as a (meth)arylloyl group. Furthermore, the metal oxide particles may be composed of particles containing multiple metal species by means of solid solution or the formation of a layered coating structure.

[0047] The average particle diameter of the metal oxide particles is preferably 5 nm or more and 200 nm or less. More preferably 20 nm or more, and even more preferably 30 nm or more. On the other hand, 120 nm or less is more preferable, and even more preferably 80 nm or less. The average particle diameter of the metal oxide particles is a volume-based average arithmetic value obtained by the laser diffraction / scattering method in accordance with JIS Z8825, and includes not only the primary particle diameter but also the secondary particle diameter, which is the aggregate of particles. The shape of the metal oxide particles is not particularly limited and may be spherical, needle-shaped, flake-shaped, rod-shaped, fibrous, irregular, etc. The inorganic oxide particles are preferably solid particles. A solid particle is a particle that does not have substantially any voids inside, and the proportion of voids is less than 5% of the volume of the solid particle.

[0048] From the viewpoint of increasing the refractive index and improving scratch resistance, the content of metal oxide particles is preferably 20% by mass or more and 80% by mass or less, based on the total solid content of the curable composition. More preferably 30% by mass or more, and even more preferably 40% by mass or more. On the other hand, more preferably 75% by mass or less, and even more preferably 70% by mass or less.

[0049] The thickness of the high refractive index layer 16 is preferably in the range of 40 nm or more and 120 nm or less. More preferably 50 nm or more, and even more preferably 70 nm or more. On the other hand, it is more preferably 100 nm or less, and even more preferably 90 nm or less. Within this range, a good low luminous reflectance can be obtained due to the optical interference effect that occurs at the interface with other layers, and light reflection can be reduced.

[0050] The high refractive index layer 16 may contain additives as needed. Examples of such additives include antifouling agents, leveling agents, defoaming agents, vibration modifiers, antibacterial agents, flame retardants, slip agents, and refractive index modifiers.

[0051] Furthermore, the composition for forming the high refractive index layer 16 preferably includes a photopolymerization initiator if the binder resin contains a reactive group that is reactive to ultraviolet light (i.e., an ultraviolet-curable resin). The composition for forming the high refractive index layer 16 may also contain a solvent as needed. The binder resin of the high refractive index layer 16 may consist only of an ultraviolet-curable resin, or it may consist of a combination of an ultraviolet-curable resin and a non-ultraviolet-curable resin.

[0052] Examples of non-UV curable resins include thermoplastic resins and thermosetting resins. Examples of thermoplastic resins include polyester resins, polyether resins, polyolefin resins, and polyamide resins. Examples of thermosetting resins include unsaturated polyester resins, epoxy resins, alkyd resins, and phenolic resins.

[0053] 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-hydroxycyclohexylphenyl-ketone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propane-1-one, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)-benzyl]phenyl}-2-methylpropane-1- Examples include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzylmethyl-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-(4-morpholinophenyl)-1-butanone, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, and N,N-dimethylaminoacetophenone. Examples of acylphosphine oxide-based photopolymerization initiators include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, and bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide. Examples of oxime ester-based photopolymerization initiators include 1,2-octanedione, 1-[4-(phenylthio)phenyl]-2-(O-benzoyl oxime), and ethanone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-1-(O-acetyl oxime). These photopolymerization initiators may be used individually or in combination of two or more.

[0054] 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 high refractive index layer 16. More preferably, it is 1% by mass or more, and 5% by mass or less.

[0055] Solvents used in the composition for forming the high refractive index layer 16 include alcohol-based solvents such as ethylene glycol monomethyl ether (EGM), 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; and amide-based solvents such as N-methylpyrrolidone, acetamide, and dimethylformamide. These solvents may be used individually or in combination of two or more.

[0056] As described above, the refractive index of the high refractive index layer 16 is preferably in the range of 1.60 or more and 2.00 or less at a measurement wavelength of 589.3 nm. If the refractive index is 1.60 or more, the anti-reflective film 10 can be made low reflectivity without drastically lowering the refractive index of the low refractive index layer 18, which will be described later. Then, by making the composition of the low refractive index layer 18 such that the refractive index is not extremely low but exhibits high scratch resistance, the anti-reflective film 10 can be made to have good scratch resistance. The refractive index of the high refractive index layer 16 is more preferably 1.65 or more, and even more preferably 1.70 or more. On the other hand, if the refractive index of the high refractive index layer 16 is 2.00 or less, it is not necessary to include a large amount of metal oxide particles in the high refractive index layer 16, thereby suppressing the shedding of metal oxide particles from the high refractive index layer 16 and obtaining good scratch resistance. The refractive index of the high refractive index layer 16 is more preferably 1.98 or less, and even more preferably 1.95 or less. As long as each layer has the above-mentioned component composition and the high-refractive-index layer 16 as a whole exhibits a refractive index within the above-mentioned range, the number of layers in the high-refractive-index layer 16 is not particularly limited. From the viewpoint of simplicity of construction, the high-refractive-index layer 16 can be composed of only one layer. In this case, that one layer should have a refractive index within the above-mentioned range.

[0057] On the other hand, the high refractive index layer 16 may be composed of two or more multilayer films with different refractive indices in order to further enhance the anti-reflective function. In particular, a two-layer configuration is preferred from the viewpoint of achieving both productivity and anti-reflective properties. When the high refractive index layer in the two-layer configuration is such that the layer located on the hard coat layer 14 side is the high refractive index layer A and the layer located on the low refractive index layer 18 side is the high refractive index layer B, the refractive index of the high refractive index layer B at the measurement wavelength of 589.3 nm is preferably in the range of 1.60 or more and 2.00 or less. More preferably it is 1.65 or more, and even more preferably 1.70 or more. On the other hand, more preferably it is 1.98 or less, and even more preferably 1.95 or less.

[0058] The refractive index of the high refractive index layer A at the measurement wavelength of 589.3 nm should be intermediate between that of the high refractive index layer B and the hard coat layer 14. Specifically, the refractive index is preferably in the range of 1.56 or more and 1.85 or less. More preferably it is 1.60 or more, and even more preferably 1.65 or more. On the other hand, it is more preferably 1.80 or less, and even more preferably 1.75 or less. The refractive index can be adjusted, for example, by selecting the metal oxide particles and adjusting their blending ratio.

[0059] In the above two-layer configuration, the thickness of the high refractive index layer B is preferably in the range of 40 nm or more and 100 nm or less, more preferably in the range of 45 nm or more and 80 nm or less, and even more preferably in the range of 50 nm or more and 70 nm or less. The thickness of the high refractive index layer A is preferably in the range of 50 nm or more and 120 nm or less, more preferably in the range of 60 nm or more and 100 nm or less, and even more preferably in the range of 70 nm or more and 90 nm or less. By setting the thickness within the above range, the anti-reflective function of the anti-reflective film 10 can be further enhanced.

[0060] The arithmetic mean roughness Sa on the surface of the high refractive index layer 16 is preferably 0.3 nm to 10 nm from the viewpoint of scratch resistance. More preferably, Sa is 0.4 nm or more, and even more preferably 0.5 nm or more. Furthermore, Sa is 7 nm or less, and even more preferably 3 nm or less.

[0061] (Low refractive index layer) In the anti-reflective film 10 according to this embodiment, a low refractive index layer 18 is provided on the surface of the high refractive index layer 16. The low refractive index layer 18 has a refractive index lower than that of the high refractive index layer 16, and the anti-reflective effect is achieved by a significant refractive index difference with the high refractive index layer 16. Furthermore, it is preferable that the refractive index of the low refractive index layer 18 is lower than that of the hard coat layer 14. The refractive index of the low refractive index layer 18 is preferably 1.29 or higher and 1.45 or lower, more preferably 1.32 or higher and 1.43 or lower. The refractive index of the low refractive index layer 18 is the refractive index at a measurement wavelength of 589.3 nm.

[0062] The composition of the low refractive index layer 18 is not particularly limited, but it is preferable that it contains metal oxide particles, hollow silica particles, a fluorine-containing compound, and a binder resin. The low refractive index layer 18 described in Patent Document 1 can be suitably applied. Its structure is briefly described below.

[0063] As the binder resin, cured products of thermosetting compounds or UV-curable compounds are preferred from the viewpoint of improving the scratch resistance of the low refractive index layer 18. Furthermore, from the viewpoint of productivity, cured products of UV-curable compounds are more preferred.

[0064] Examples of UV-curable resins include monomers, oligomers, and prepolymers having UV-reactive reactive groups. Examples of UV-reactive reactive groups include radical polymerization-type reactive groups having ethylenically unsaturated bonds, 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, and acryloyl groups and methacryloyl groups are particularly preferred. In other words, the use of (meth)acrylate is particularly preferred.

[0065] As for specific (meth)acrylates, those listed above as examples of (meth)acrylate compounds without an isocyanuric acid skeleton to be included in the high refractive index layer 16 can also be suitably used here. It is preferable to include polyfunctional (meth)acrylates with five or more functions, and it is also preferable to include dimers, with a preferred content being in the range of 25% to 50% by mass, more preferably 30% to 40% by mass, based on the total solid content of the polyfunctional (meth)acrylate, similar to the (meth)acrylate compounds without an isocyanuric acid skeleton in the high refractive index layer 16.

[0066] The inorganic oxide particles, when included in the low refractive index layer 18, form protrusions on the surface of the low refractive index layer 18. The formation of these protrusions on the surface of the low refractive index layer 18 by the inorganic oxide particles allows the low refractive index layer 18 to have good scratch resistance.

[0067] As inorganic oxide particles, those similar to those listed above as specific examples of metal oxide particles contained in the high refractive index layer 16 can be suitably used. Here again, the inorganic oxide particles are preferably solid particles, but they may also be hollow particles.

[0068] In order to obtain good scratch resistance by forming protrusions on the surface of the low refractive index layer 18 with inorganic oxide particles, the difference (rd) between the average particle diameter r of the inorganic oxide particles and the average thickness d of the low refractive index layer 18 is preferably 10 nm or more. The difference (rd) 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 protrusions and maintaining transparency, the difference (rd) is preferably 300 nm or less. More preferably 200 nm or less, and even more preferably 100 nm or less.

[0069] The average particle diameter r of the inorganic oxide particles is preferably in the range of 60 nm to 400 nm, although this also depends on the average thickness d of the low refractive index layer 18. More preferably it is 70 nm or more, and even more preferably 90 nm or more. Furthermore, it is even 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 the laser diffraction / scattering method in accordance with JIS Z8825, and includes not only the primary particle diameter but also the secondary particle diameter, which is the aggregate of particles.

[0070] The inorganic oxide particle content in the low refractive index layer 18 is preferably 0.1% by mass or more and 4.0% by mass or less relative to 100% by mass of the solid content of the low refractive index layer 18. When the inorganic oxide particle content in the low refractive index layer 18 is 0.1% by mass or more relative to 100% by mass of the solid content of the low refractive index layer 18, excellent scratch resistance can be obtained. From this viewpoint, the inorganic oxide particle content in the low refractive index layer 18 is more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more, relative to 100% by mass of the solid content of the low refractive index layer 18. Furthermore, when the inorganic oxide particle content in the low refractive index layer 18 is 4.0% by mass or less relative to 100% by mass of the solid content of the low refractive index layer 18, high transparency can be obtained. From this viewpoint, the inorganic oxide particle content in the low refractive index layer 18 is more preferably 3.5% by mass or less, and even more preferably 3.2% by mass or less, relative to 100% by mass of the solid content of the low refractive index layer 18. The solid components of the low refractive index layer 18 referred to here are those components that are not immobilized in the binder resin and are liquid at room temperature, excluding those components. The solid components of the low refractive index layer 18 include inorganic oxide particles, hollow silica particles, binder resin, and fluorine-containing compounds immobilized in the binder resin. Additives such as oil components and surfactants that are not immobilized in the binder resin are not included.

[0071] Hollow silica particles are particles with an average particle diameter smaller than the average thickness of the low refractive index layer 18. It is preferable that the hollow silica particles have an average particle diameter smaller than the inorganic oxide particles that form protrusions on the surface of the low refractive index layer 18. Hollow silica particles are particles that do not substantially contribute to the formation of surface irregularities in the low refractive index layer 18. Hollow silica particles are particles that have cavities inside, and the proportion of cavities is 5% or more of the volume. "Hollow" refers to a shell structure consisting of an outer shell and internal cavities, or a porous structure having numerous cavities. The hollow structure of hollow silica particles allows for a reduction in the refractive index of the low refractive index layer 18, thereby reducing light reflection. The shape of the hollow silica particles is not particularly limited, but spherical, spindle-shaped, oval, plate-shaped, cubic, and irregular shapes are preferred. Of these, spherical, plate-shaped, and cubic shapes are particularly preferred.

[0072] In hollow silica particles, the proportion of cavities is preferably 10% to 80% of the volume. When the proportion of cavities is 10% or more of the volume, the refractive index can be lowered, reducing light reflection. More preferably, it is 20% or more of the volume, and even more preferably 30% or more of the volume. On the other hand, when the proportion of cavities is 80% or less of the volume, the decrease in the dispersibility of the hollow silica particles can be suppressed. More preferably, it is 60% or less of the volume.

[0073] The average particle diameter of the hollow silica particles is preferably between 5 nm and 100 nm, although this also depends on the average thickness of the low refractive index layer 18. More preferably, it is 20 nm or more, and even more preferably, 40 nm or more. Furthermore, 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-reflective effect and transparency of the low refractive index layer 18 can be obtained. The average particle diameter is a volume-based average arithmetic value obtained by the laser diffraction / scattering method in accordance with JIS Z8825. This includes not only the primary particle diameter but also the secondary particle diameter, which is the aggregate of particles.

[0074] 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, 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-reflective effect can be obtained.

[0075] The content of hollow silica particles in the low refractive index layer 18 is preferably 6.0% by mass or more and 49.9% by mass or less relative to 100% by mass of the solid content of the low refractive index layer 18. When the content of hollow silica particles in the low refractive index layer 18 is 6.0% by mass relative to 100% by mass of the solid content of the low refractive index layer 18, excellent anti-reflective properties can be obtained. From this viewpoint, the content of hollow silica particles in the low refractive index layer 18 is more preferably 10% by mass or more, even more preferably 20% by mass or more, and particularly preferably 30% by mass or more, relative to 100% by mass of the solid content of the low refractive index layer 18. Furthermore, when the content of hollow silica particles in the low refractive index layer 18 is 49.9% by mass or less relative to 100% by mass of the solid content of the low refractive index layer 18, the decrease in scratch resistance can be suppressed. From this viewpoint, the content of hollow silica particles in the low refractive index layer 18 is more preferably 45% by mass or less, and even more preferably 40% by mass or less, relative to 100% by mass of the solid content of the low refractive index layer 18.

[0076] Furthermore, the total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 18 is preferably 10% by mass or more and 50% by mass or less relative to 100% by mass of the solid content of the low refractive index layer 18. If the total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 18 is 10% by mass or more relative to 100% by mass of the solid content of the low refractive index layer 18, excellent scratch resistance can be obtained. Also from this viewpoint, the total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 18 is more preferably 20% by mass or more, and even more preferably 30% by mass or more, relative to 100% by mass of the solid content of the low refractive index layer 18. On the other hand, if the total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 18 is 50% by mass or less relative to 100% by mass of the solid content of the low refractive index layer 18, the low refractive index layer 18 can sufficiently retain inorganic oxide particles and hollow silica particles, thus providing excellent scratch resistance. Furthermore, from this viewpoint, the total amount of inorganic oxide particles and hollow silica particles in the low refractive index layer 18 is more preferably 48% by mass or less, even more preferably 46% by mass or less, and particularly preferably 43% by mass or less, based on 100% by mass of the solid content of the low refractive index layer 18.

[0077] In the low refractive index layer 18, the fluorine-containing compound can function as an antifouling agent. Furthermore, because the surface slipperiness of the low refractive index layer 18 is improved, it can contribute to improved scratch resistance. Examples of fluorine-containing compounds include (meth)acrylates containing perfluoroalkyl groups. Such compounds include "KY-1203" from Shin-Etsu Chemical Co., Ltd., "Megafac RS-75" from DIC Corporation, "Optool DAC-HP" from Daikin Industries, Ltd., and "Futergent 601AD" from Neos Corporation. Such fluorine-containing compounds can suppress the adhesion of dirt and fingerprints, and facilitate the removal of dirt and fingerprints.

[0078] The content of the fluorine-containing compound in the low refractive index layer 18 is preferably 1.0% by mass or more and 15.0% by mass or less based on 100% by mass of the solid content of the low refractive index layer 18. When the content of the fluorine-containing compound in the low refractive index layer 18 is 1.0% by mass or more based on 100% by mass of the solid content of the low refractive index layer 18, the slipperiness of the surface of the low refractive index layer 18 is improved, and scratch resistance is improved. In addition, stain resistance is improved. From this viewpoint, the content of the fluorine-containing compound in the low refractive index layer 18 is more preferably 2.0% by mass or more, and even more preferably 3.0% by mass or more, based on 100% by mass of the solid content of the low refractive index layer 18. Furthermore, when the content of the fluorine-containing compound in the low refractive index layer 18 is 15.0% by mass or less based on 100% by mass of the solid content of the low refractive index layer 18, the decrease in scratch resistance is suppressed. Furthermore, from this viewpoint, the content of the fluorine-containing compound in the low refractive index layer 18 is more preferably 13.0% by mass or less, even more preferably 10.0% by mass or less, and particularly preferably 5.0% by mass or less, based on 100% by mass of the solid content of the low refractive index layer 18.

[0079] The refractive index of the low refractive index layer 18 is not particularly limited as long as it is lower than that of the high refractive index layer 16 and preferably lower than that of the hard coat layer 14, but is preferably 1.35 or more and 1.49 or less. If the refractive index is 1.35 or more, the strength of the low refractive index layer 18 can be made sufficient and good scratch resistance can be obtained. On the other hand, if the refractive index is 1.49 or less, the reflectivity of the anti-reflective film 10 can be made even lower. From the above viewpoint, the refractive index of the low refractive index layer 18 is more preferably 1.38 or more and 1.46 or less, and even more preferably 1.40 or more and 1.44 or less.

[0080] The thickness of the low refractive index layer 18 is preferably in the range of 80 nm to 110 nm. More preferably 85 nm or more, and even more preferably 90 nm or more. Furthermore, it is more preferably 105 nm or less, and even more preferably 100 nm or less. Within this range, a good low luminous reflectance can be obtained, and light reflection can be reduced.

[0081] The low refractive index layer 18 can be formed using a composition comprising inorganic oxide particles, hollow silica particles, a fluorine-containing compound, and a binder resin. The fluorine-containing compound and the binder resin preferably have UV-reactive groups. Examples of UV-reactive groups include (meth)acryloyl groups. When the fluorine-containing compound and the binder resin have UV-reactive groups, the scratch resistance of the low refractive index layer 18 is improved, and the scratch resistance of the anti-reflective film 10 is improved. The composition for forming the low refractive index layer 18 preferably includes a photopolymerization initiator when the binder resin contains a UV-reactive group (UV-curable resin). The composition for forming the low refractive index layer 18 may also contain a solvent as needed. The binder resin of the low refractive index layer 18 may be composed of a UV-curable resin, a non-UV-curable resin, or a combination of a UV-curable resin and a non-UV-curable resin. As solvents used in the non-UV curable resin, photopolymerization initiator, and composition for forming the low refractive index layer 18, those similar to the components used in the high refractive index layer 16 and those listed above as specific examples can be suitably used.

[0082] In addition, the low refractive index layer 18 may contain additives as needed. Examples of such additives include antifouling agents, dispersants, leveling agents, defoaming agents, vibration modifiers, antibacterial agents, flame retardants, slip agents, and refractive index modifiers.

[0083] (Method of manufacturing anti-reflective film) To manufacture the anti-reflective film 10, first, a composition for forming a hard coat layer 14 is applied to the surface of a base film 12, and after drying as necessary, it is cured by irradiation with ionizing radiation such as ultraviolet light to form a hard coat layer 14 on the surface of the base film 12. Then, a composition for forming a high refractive index layer 16 is applied to the surface of the hard coat layer 14, and after drying as necessary, it is cured by irradiation with ionizing radiation such as ultraviolet light to form a high refractive index layer 16 on the surface of the hard coat layer 14. Furthermore, a composition for forming a low refractive index layer 18 is applied to the surface of the high refractive index layer 16, and after drying as necessary, it is cured by irradiation with ionizing radiation such as ultraviolet light to form a low refractive index layer 18 on the surface of the high refractive index layer 16. By going through these steps, the anti-reflective film 10 can be manufactured. If the high refractive index layer 16 is to have a multilayer structure, the process of applying the composition for each layer, drying as necessary, and curing can be repeated.

[0084] When forming a hard coat layer 14 on the surface of the base film 12, the surface of the base film 12 may be subjected to a surface treatment before coating in order to improve the adhesion between the base 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.

[0085] The composition forming the hard coat layer 14, the composition forming the high refractive index layer 16, and the composition forming the low refractive index layer 18 can be coated using 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.

[0086] The drying process for each layer is not particularly limited as long as it removes the solvent used in the coating liquid, but it is preferable to carry it out at a temperature of 50 to 150°C for about 10 to 180 seconds.

[0087] For UV irradiation of each layer, high-pressure mercury lamps, electrodeless (microwave) lamps, xenon lamps, metal halide lamps, and other UV irradiation devices can be used. UV irradiation may be carried out under an inert gas atmosphere such as nitrogen, if necessary. The UV irradiation dose is not particularly limited, but is generally between 50 and 800 mJ / cm². 2 Preferably, 100-300 mJ / cm² 2 This is preferable.

[0088] (Characteristics of anti-reflective film) The anti-reflective film 10 having the above configuration comprises a base film 12, a hard coat layer 14 formed on the surface of the base film 12, a high refractive index layer 16 formed on the surface of the hard coat layer 14, and a low refractive index layer 18 formed on the surface of the high refractive index layer 16. The high refractive index layer 16 is composed of a cured product of an ionizing radiation curable composition containing a (meth)acrylate compound and a (meth)acrylate compound having an isocyanuric acid skeleton. In the high refractive index layer 16, the content of the (meth)acrylate compound having an isocyanuric acid skeleton is 10% by mass or more and 35% by mass or less of the solid content of the binder resin. Due to the contribution of this high refractive index layer 16, the anti-reflective film 10 has excellent scratch resistance. Furthermore, the hard coat layer 14 and the low refractive index layer 18, which were given as specific examples above, also possess high scratch resistance. By constituting the anti-reflective film 10 together with the high refractive index layer 16 containing a predetermined amount of (meth)acrylate compound having an isocyanuric acid skeleton, the entire anti-reflective film 10 becomes particularly scratch-resistant.

[0089] <Other forms of anti-reflective film> The anti-reflective film according to the present invention is not limited to the configuration of the anti-reflective film 10 according to the first embodiment. Other embodiments of the anti-reflective film according to the present invention will be described below.

[0090] (Second embodiment) Figure 2 shows an anti-reflective film 20 according to the second embodiment. The anti-reflective film 20 according to the second embodiment includes a base film 12, a hard coat layer 14 formed on one surface of the base film 12, a high refractive index layer 16 formed on the surface of the hard coat layer 14, and a low refractive index layer 18 formed on the surface of the high refractive index layer 16. It also has a transparent adhesive layer 22 on the other surface of the base film 12. A release film 24 is placed on the surface of the transparent adhesive layer 22 as needed. The release film 24 functions as a protective layer for the transparent adhesive layer 22 before use of the anti-reflective film 20 and is peeled off from the transparent adhesive layer 22 when the anti-reflective film 20 is used.

[0091] The anti-reflective film 20 according to the second embodiment differs from the anti-reflective film 10 according to the first embodiment in that it has a transparent adhesive layer 22 on the other surface of the base film 12. Otherwise, it is the same as the anti-reflective film 10 according to the first embodiment, and a description of the similar configuration will be omitted.

[0092] The transparent adhesive layer 22 is for ensuring good adhesion of the anti-reflective film 20 to the surface of a display or the like. Furthermore, the presence of the transparent adhesive layer 22 of the anti-reflective film 20 also has the effect of preventing the glass of the display or the like from shattering. In other words, the anti-reflective film 20 also functions as a shatterproof film.

[0093] The adhesive composition forming the transparent adhesive layer 22 may contain known adhesive resins such as acrylic adhesives, silicone adhesives, and urethane adhesives. Among these, acrylic adhesives are preferred from the viewpoint of optical transparency and heat resistance. The adhesive composition preferably contains a crosslinking agent to enhance the cohesive force of the transparent adhesive layer 22. Examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, and chelate crosslinking agents.

[0094] The adhesive composition may contain additives as needed. Examples of known additives include plasticizers, silane coupling agents, surfactants, antioxidants, fillers, curing accelerators, and curing retarders. Furthermore, from the viewpoint of productivity, the composition may be diluted using organic solvents.

[0095] The thickness of the transparent adhesive layer 22 is not particularly limited, but is preferably in the range of 5 μm or more and 100 μm or less. More preferably it is 10 μm or more and 50 μm or less.

[0096] The transparent adhesive layer 22 can be formed by methods such as directly applying the adhesive composition to the other surface of the base film 12, applying the adhesive composition to the surface of the release film 24 and then transferring it to the other surface of the base film 12, or applying the adhesive composition to the surface of the first release film, then bonding the second release film, peeling off one of the release films and transferring it to the other surface of the base film 12.

[0097] From the viewpoint of preventing glass from shattering, the transparent adhesive layer 22 preferably has an adhesive strength of 4N / 25mm or more to the glass. More preferably it is 6N / 25mm or more, and even more preferably 10N / 25mm or more.

[0098] (Third embodiment) Figure 3 shows an anti-reflective film 30 according to the third embodiment. The anti-reflective film 30 according to the third embodiment includes a base film 12, a hard coat layer 14 formed on one surface of the base film 12, a high refractive index layer 16 formed on the surface of the hard coat layer 14, a low refractive index layer 18 formed on the high refractive index layer 16, and a protective film 28 disposed on the surface of the low refractive index layer 18 via an adhesive layer 26. It also has a transparent adhesive layer 22 on the other surface of the base film 12. A release film 24 is disposed on the surface of the transparent adhesive layer 22 as needed.

[0099] The anti-reflective film 30 according to the third embodiment differs from the anti-reflective film 20 according to the second embodiment in that it has a protective film 28 on the surface of the low refractive index layer 18 via an adhesive layer 26. In all other respects, it is the same as the anti-reflective film 20 according to the second embodiment, and a description of the similar configuration will be omitted.

[0100] The protective film 28 can prevent scratches on the surface of the low refractive index layer 18 when handling the anti-reflective film 30, such as during continuous processing in a roll process or when it is laminated to a display. The protective film 28 is attached to the surface of the low refractive index layer 18 via an adhesive layer 26. After processing the anti-reflective film 30, the protective film 28 is peeled off from the surface of the low refractive index layer 18 together with the adhesive layer 26. For this reason, the adhesive force between the protective film 28 and the adhesive layer 26 is stronger than the adhesive force between the low refractive index layer 18 and the adhesive layer 26, and the adhesive force between the low refractive index layer 18 and the adhesive layer 26 is adjusted to allow for interfacial peeling.

[0101] The materials constituting the protective film 28 can be appropriately selected from those exemplified as materials 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 2 μm to 200 μm.

[0102] 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 preferred because they have excellent transparency and heat resistance. The acrylic adhesive is preferably formed from an adhesive composition containing a (meth)acrylic polymer and a crosslinking agent.

[0103] (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.

[0104] 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 individually or in combination of two or more.

[0105] The adhesive composition may contain other additives in addition to the (meth)acrylic polymer and crosslinking agent. Examples of other additives include crosslinking accelerators, crosslinking retarders, tackifiers, antistatic agents, silane coupling agents, plasticizers, release agents, pigments, dyes, wetting agents, thickeners, UV absorbers, preservatives, antioxidants, metal deactivators, alkylating agents, and flame retardants. These are selected and used appropriately depending on the application and intended use of the adhesive.

[0106] The thickness of the adhesive layer 26 is not particularly limited, but is preferably in the range of 1 to 10 μm. More preferably, it is in the range of 2 to 7 μm.

[0107] Although embodiments of the present invention have been described above, the present invention is not limited in any way to the above embodiments, and various modifications are possible without departing from the spirit of the present invention.

[0108] For example, in the above embodiment, it is stated that a surface treatment may be applied to the surface of the base film 12, but instead of surface treatment, an easy-adhesion layer may be provided on the surface of the base film 12.

[0109] In addition, in each of the above embodiments, an antifouling layer may be formed on the surface of the low refractive index layer 18 to further enhance its antifouling properties. When an antifouling layer is provided on the surface of the anti-reflective film 20, it is preferable that the refractive index difference between the low refractive index layer 18 and the antifouling layer be small from the viewpoint of reducing reflection at the interface. The refractive index of the antifouling layer is preferably 1.6 or less, and more preferably 1.55 or less. As the material of the antifouling layer, fluorine-containing silane compounds or fluorine-containing organic compounds are preferred. The antifouling layer can be formed by wet methods such as reverse coating, die coating, and gravure coating, or by dry processes such as vacuum deposition and CVD. The thickness of the antifouling layer is usually about 1 nm to 50 nm, preferably 2 nm to 30 nm, and more preferably 3 nm to 20 nm. Surface treatment may also be applied before forming the antifouling layer. Examples of surface treatments include corona treatment, plasma treatment, hot air treatment, ozone treatment, and ultraviolet treatment.

[0110] Furthermore, although the protective film 28 is shown as being added to the anti-reflective film 20 of the second embodiment shown in Figure 2, as shown in Figure 3, it may also be added to the anti-reflective film 10 of the first embodiment shown in Figure 1.

[0111] Furthermore, various functional layers, such as a gas barrier-enhancing layer, an antistatic layer, and an oligomer-blocking layer, may be pre-applied to the surface of the base film 12 before forming each layer. As the antistatic layer, the one described in Patent Document 1 can be suitably applied. [Examples]

[0112] The present invention will be described in detail below using examples and comparative examples. Unless otherwise specified, the preparation and evaluation of samples were carried out at room temperature in air.

[0113] (Examples 1-8, Comparative Examples 1-5) <Preparation of compositions for forming a hard coat layer> A hard coat layer forming composition was prepared by adding the photopolymerization initiator "Omnirad127" (manufactured by IGM Resins BV, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one) to the UV-curable composition "Luxidia ESS-620" (manufactured by DIC, urethane acrylate resin, solvent: ethyl acetate, solids content: 79% by mass) to the total amount of the hard coat layer forming composition, and then adding ethyl acetate to bring the solids content to 40% by mass.

[0114] <Preparation of compositions for forming high refractive index layers> Each component was blended to achieve the composition shown in Table 1 (unit: mass %) of the total solids, and PGM was added to achieve the solids concentration shown in Table 1 to prepare a composition for forming a high refractive index layer.

[0115] The materials used as constituent components of the high refractive index layer forming composition are as follows: • Polyfunctional acrylate ((meth)acrylate compound without an isocyanuric acid skeleton) - "Aronics MT-3041" manufactured by Toagosei, polyfunctional acrylate, solid content concentration: 100% by mass • Isocyanurate compound ((meth)acrylate compound having an isocyanuric acid skeleton) - "Aronics M-315" manufactured by Toagosei, a mixture of ethylene oxide-modified diacrylate isocyanurate (8% by mass) and ethylene oxide-modified triacrylate isocyanurate (92% by mass), solid content concentration: 100% by mass • Aliphatic UA-Sartomer "CN968 NS" aliphatic polyester urethane acrylate, solid content concentration: 100% by mass • PETA-Toagosei's "Aronics M-933," a pentaerythritol acrylate reaction product mainly composed of pentaerythritol triacrylate, solid content concentration: 100% by mass Titanium dioxide particles - Ishihara Sangyo Co., Ltd. "LDB-102-45", titanium dioxide particles (coated with aluminum hydroxide and silicon dioxide), dispersant, solvent: PGM, solids concentration: 45% by mass • Photopolymerization initiator - "Omnirad127" as described above.

[0116] <Preparation of composition for forming a low refractive index layer> A composition for forming a low refractive index layer was prepared by blending the components so that, in terms of mass percent concentration of total solids, the composition consisted of 55% by mass of UV-curable resin, 3.8% by mass of alumina particles (added as alumina sol), 8% by mass of fluorine-containing compound, 30% by mass of hollow silica particles, and 3% by mass of photopolymerization initiator. The solids concentration was then adjusted to 3% by mass using a solvent (MEK / PGM = 1 / 3).

[0117] The materials used as constituent components of the low refractive index layer formation composition are as follows: • UV-curing resin - "Arronix MT-3041" as described above. • Alumina sol - Toyo Chem's "RioDuras 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 - Shin-Etsu Chemical Co., Ltd. "KY-1203", perfluoroalkyl group-containing (meth)acrylate, solvent: MIBK, solids content concentration: 20% by mass • Hollow silica particles - JGC Catalysts & Chemicals "Thru-Ria 4320", average particle size: 60 nm, solvent: MIBK, solids content concentration: 20% by mass • Photopolymerization initiator - "Omnirad127" as described above.

[0118] <Preparation of the hard coat layer> For each of Examples 1-8 and Comparative Examples 1-5, a hard coat layer-forming composition was applied to a base film (Toray Industries' "Lumirror #50-U403," a polyethylene terephthalate film, 50 μm thick) using a #4 wire bar. After drying at 80°C for 3 minutes, a light intensity of 80 mJ / cm² was applied using an electrodeless (microwave) lamp. 2 A hard coat layer was formed by irradiating it with ultraviolet light.

[0119] <Fabrication of high refractive index layers> For each of Examples 1-8 and Comparative Examples 1-5, the high refractive index layer-forming composition was applied to the surface of the hard coat layer using a #4 wire bar, dried at 80°C for 3 minutes, and then exposed to light at an intensity of 150 mJ / cm using an electrodeless (microwave) lamp. 2 A high refractive index layer was formed by irradiating it with ultraviolet light.

[0120] <Fabrication of low refractive index layers> For each of Examples 1-8 and Comparative Examples 1-5, the low refractive index layer-forming composition was applied to the surface of the high refractive index layer using a #4 wire bar, dried at 80°C for 60 seconds, and then exposed to light at a light intensity of 150 mJ / cm² using an electrodeless (microwave) lamp under a nitrogen atmosphere. 2 A low refractive index layer was formed by irradiating it with ultraviolet light.

[0121] (Example 9) Each component was blended to achieve the composition shown in Table 2 (unit: mass %) of the total solids, and PGM was added to achieve the solids concentration shown in Table 2 to prepare a composition for forming the high refractive index layer B. An anti-reflective film of Example 9 was prepared in the same manner as in Example 6, except that after forming a high refractive index layer (referred to as high refractive index layer A) in Example 6, a second high refractive index layer, high refractive index layer B, was further formed. The anti-reflective film of Example 9 has two high refractive index layers. Based on the above, anti-reflective films according to Examples 1-9 and Comparative Examples 1-5 were prepared.

[0122] <Evaluation Method> (Thickness and refractive index of each layer) For each sample, the thickness and refractive index of the hard coat layer, high refractive index layer, and low refractive index layer were evaluated. In this process, after each layer was formed, the thickness of each layer and the refractive index at a wavelength of 589.3 nm were calculated by curve fitting using the least squares method between the reflection spectral spectrum in the wavelength range of 380-780 nm obtained using a micro-spectrometer (OPTM-F1, manufactured by Otsuka Electronics) and the theoretical spectrum derived based on Fresnel's equation.

[0123] (Scratch resistance) A flat abrasion tester (DAS-400, manufactured by Daiei Kagaku Seiki Seisakusho) was used to test steel wool #0000 (manufactured by Nippon Steel Wool Co., Ltd.), fixed to a 20mm x 20mm flat abrasive, on the surface of the low refractive index layer of an anti-reflective film, which was then moved back and forth. The stroke length of the test stand was 50mm, the reciprocating speed of the test stand was 60 reciprocations / minute, and the reciprocating motion was performed with a load of 1.0kg. Up to 500 reciprocations, the sample was visually inspected every 100 reciprocations, and thereafter every 500 reciprocations thereafter. The maximum number of reciprocations until a scratch of 10mm or longer was observed was used as the evaluation value. An evaluation value of 1200 or more reciprocations can be considered to indicate sufficient scratch resistance. Furthermore, an evaluation value of 2000 or more reciprocations indicates high scratch resistance, and an evaluation value of 2500 or more reciprocations indicates particularly high scratch resistance.

[0124] (Visibility reflectance) The back surface of the fabricated anti-reflective film (the side opposite the low refractive index layer) was roughened with #400 grit sandpaper and painted black. The 5° specular reflectance of the surface of the low refractive index layer at wavelengths of 380 nm to 780 nm was measured using a UV-Vis-Near-Infrared spectrophotometer (Shimadzu Corporation "UV-3600"). The luminous reflectance was calculated by multiplying this measurement by the relative luminous efficiency value. If the luminous reflectance is 2.0% or less, the anti-reflective properties can be considered sufficient.

[0125] <Evaluation Results> Tables 1 and 2 below show the component composition of the high refractive index layer and the thickness of each layer, along with the evaluation results for Examples 1-9 and Comparative Examples 1-5.

[0126] [Table 1]

[0127] [Table 2]

[0128] In Comparative Example 1, where the curable composition constituting the high refractive index layer does not contain an isocyanurate compound, the scratch resistance evaluation result was poor, not reaching 1200 cycles in the evaluation value. Similarly, in Comparative Example 2, where the isocyanurate compound was not present in more than 10% by mass of the solid content of the binder resin, and in Comparative Example 3, where it was present in more than 35% by mass, the scratch resistance evaluation results were also poor.

[0129] In Comparative Examples 4 and 5, the curable composition constituting the high refractive index layer does not contain an isocyanurate compound, but instead contains different types of (meth)acrylates. Specifically, Comparative Example 4 uses an aliphatic urethane acrylate, and Comparative Example 5 uses a trifunctional acrylate. These (meth)acrylates are representative examples of those with moderate toughness and flexibility, but because they do not have an isocyanuric acid skeleton, the evaluation results for scratch resistance are poor.

[0130] In contrast, in Examples 1 to 9, where the curable composition constituting the high refractive index layer contained an isocyanurate compound in an amount of 10% to 35% by mass of the solid content of the binder resin (100% by mass), high scratch resistance exceeding 1200 cycles was obtained in the evaluation value. This indicates that including a (meth)acrylate compound having an isocyanuric acid skeleton in the curable composition constituting the high refractive index layer improves the scratch resistance of the anti-reflective film. Furthermore, in Examples 1 to 9, a luminous reflectance of 2.0% or less was obtained, which is sufficiently high for the performance of an anti-reflective film. In particular, Example 9, having a two-layer high refractive index structure (medium refractive index and high refractive index from the base film side), obtained an even lower luminous reflectance than Examples 1 to 8, and thus exhibits even higher anti-reflective properties.

[0131] As described above, in an anti-reflective film having a base film, a hard coat layer formed on the surface of the base film, a high refractive index layer formed on the surface of the hard coat layer, and a low refractive index layer formed on the surface of the high refractive index layer, the high refractive index layer is composed of a cured product of an ionizing radiation curable composition containing, together with a (meth)acrylate compound that does not have an isocyanuric acid skeleton, 10% to 35% by mass of the solid content of the binder resin, of an isocyanuric acid skeleton, thereby providing an anti-reflective film with excellent scratch resistance due to the contribution of the high refractive index layer.

[0132] Although embodiments of the present invention have been described above, the present invention is not limited in any way to the above embodiments, and various modifications are possible without departing from the spirit of the present invention. [Explanation of Symbols]

[0133] 10, 20, 30 Anti-reflective film 12. Base film 14. Hard court layer 16 High refractive index layer 18 Low refractive index layer 22 Transparent adhesive layer 24 Release film 26 Adhesive layer 28 protective films

Claims

1. It comprises a base film, a hard coat layer formed on the surface of the base film, a high refractive index layer formed on the surface of the hard coat layer, and a low refractive index layer formed on the surface of the high refractive index layer. The high refractive index layer is composed of a cured product of an ionizing radiation-curable composition containing a binder resin and metal oxide particles. The aforementioned binder resin, together with a (meth)acrylate compound that does not have an isocyanuric acid skeleton, An anti-reflective film containing an isocyanuric acid skeleton (meth)acrylate compound in an amount of 10% to 35% by mass of the solid content of the binder resin, based on 100% by mass of solids.

2. The anti-reflective film according to claim 1, wherein the (meth)acrylate compound having an isocyanuric acid skeleton contains 60% by mass or more of a trifunctional (meth)acrylate compound having an isocyanuric acid skeleton, based on 100% by mass of the solid content of the (meth)acrylate compound having an isocyanuric acid skeleton.

3. The anti-reflective film according to claim 1 or claim 2, wherein the metal oxide particles are titanium oxide particles.

4. The anti-reflective film according to claim 1 or claim 2, wherein the high refractive index layer consists of one layer and has a refractive index of 1.60 or more and 2.00 or less.

5. The anti-reflective film according to claim 1 or claim 2, wherein the high refractive index layer consists of two layers, and of the two layers, the refractive index of the layer located on the low refractive index layer side of the high refractive index layer is 1.60 or more and 2.00 or less, and the refractive index of the layer located on the hard coat layer side is 1.56 or more and 1.85 or less.

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