Anti-reflective film

Abstract

We provide an anti-reflective film with high abrasion resistance. [Solution] An anti-reflective film 10 having a base film 12, a hard coat layer 14 formed on the surface of the base film 12, and a low refractive index layer 16 formed on the surface of the hard coat layer 14, wherein the low refractive index layer 16 is composed of a cured product of an ionizing radiation curable composition containing a (meth)acrylate compound having a reactive group, hollow silica particles, and alumina particles surface-treated with a silane coupling agent having a reactive group capable of bonding with the (meth)acrylate compound, and the skewness of the three-dimensional surface roughness of the surface of the anti-reflective film 10 is 1.00 or more and 1.14 or less, and the crustosis is 5.0 or more and 11.0 or less.

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. to prevent external light from reflecting onto the screen. As an antireflection film, one having a hard coat layer and an antireflection layer (low refractive index layer) on a base film in this order is known. For example, in Patent Document 1 by 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

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In an antireflection film, especially one disposed on the surface of a touch panel and frequently receiving finger contact, it is advantageous to have high antifouling properties in addition to high antireflection properties as in the antireflection film disclosed in Patent Document 1. As disclosed in Patent Document 1, by devising the component composition of the low refractive index layer constituting the antireflection film, it becomes possible to achieve both optical properties such as antireflection properties and other properties such as antifouling properties in the antireflection film. However, even if a low refractive index layer excellent in properties such as antifouling properties is provided on the antireflection film, when the finger contact is repeated on the antireflection film, the surface of the antireflection film may wear, and properties such as antifouling properties that the low refractive index layer can originally exhibit may deteriorate. Therefore, in an antireflection film that frequently receives finger contact, from the viewpoint of enhancing the durability during use and maintaining those properties in addition to having excellent properties such as high antireflection properties and antifouling properties, having high abrasion durability becomes an important property.

[0005] The problem to be solved by the present invention is to provide an antireflection film having high abrasion durability.

Means for Solving the Problem

[0006] To solve the above problems, the antireflection film according to the present invention has the following configuration. [1] The antireflection film according to the present invention is an antireflection film having a base film, a hard coat layer formed on the surface of the base film, and a low refractive index layer formed on the surface of the hard coat layer, wherein the low refractive index layer is composed of a cured product of a radiation-curable composition containing a (meth)acrylate compound having a reactive group, hollow silica particles, and alumina particles surface-treated with a silane coupling agent having a reactive group capable of forming a bond with the (meth)acrylate compound, and the skewness in the three-dimensional surface roughness of the surface of the antireflection film is 1.00 or more and 1.14 or less, and the kurtosis is 5.0 or more and 11.0 or less.

[0007] [2] In the embodiment of [1] above, in the three-dimensional surface roughness profile of the surface of the anti-reflective film, the number of protrusions having a height of 40 nm or more from the average plane is 1 mm 2 The number of protrusions is between 100 and 300 per unit area, and the number of protrusions having a height of 100 nm or more from the average surface is 1 mm 2 It's best if there are 5 or fewer per person.

[0008] [3] In the embodiment of [1] or [2] above, the content of the alumina particles in the low refractive index layer is preferably 1.0% by mass or more and 8.0% by mass or less with respect to 100% by mass of the solid content of the ionizing radiation curable composition. [Effects of the Invention]

[0009] 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, and a low refractive index layer formed on the surface of the hard coat layer, wherein the low refractive index layer is composed of a cured product of an ionizing radiation curable composition containing a (meth)acrylate compound having a reactive group, hollow silica particles, and alumina particles surface-treated with a silane coupling agent having a reactive group capable of bonding with the (meth)acrylate compound, and the skewness of the three-dimensional surface roughness of the surface of the anti-reflective film is 1.00 or more and 1.14 or less, and the crustosis is 5.0 or more and 11.0 or less. Because the low refractive index layer is composed of a cured product of a composition containing, in addition to the (meth)acrylate compound, alumina particles surface-treated with a silane coupling agent having a reactive group capable of bonding with the (meth)acrylate compound, the anti-reflective film has excellent scratch resistance as well as high stain resistance and abrasion resistance. In particular, a high degree of improvement in wear resistance can be obtained when the skewness of the three-dimensional surface roughness of the anti-reflective film is between 1.00 and 1.14, and the crustosis is between 5.0 and 11.0. The skewness and crustosis of the three-dimensional surface roughness of the anti-reflective film can be mainly controlled by the distribution of alumina particles in the low refractive index layer.

[0010] In the embodiment described in [2] above, the number of protrusions having a height of 40 nm or more from the average plane in the three-dimensional surface roughness profile of the surface of the anti-reflective film is 1 mm 2 The number of protrusions is between 100 and 300 per unit area, and the number of protrusions having a height of 100 nm or more from the average surface is 1 mm 2 By having five or fewer particles per unit area, the anti-reflective film exhibits particularly excellent abrasion resistance and high transparency.

[0011] In the embodiment described in [3] above, the abrasion resistance and transparency of the anti-reflective film are effectively enhanced by having the alumina particle content in the low refractive index layer be 1.0% by mass or more and 8.0% by mass or less based on 100% by mass of the solid content of the ionizing radiation-curable composition. [Brief explanation of the drawing]

[0012] [Figure 1] This is a cross-sectional view of an anti-reflective film according to the first embodiment of the present invention. [Figure 2] This is a cross-sectional view of an anti-reflective film according to a second embodiment of the present invention. [Figure 3] This is a cross-sectional view of an anti-reflective film according to a third embodiment of the present invention. [Figure 4] This is a cross-sectional view of an anti-reflective film according to a fourth embodiment of the present invention. [Figure 5] This is a cross-sectional view of an anti-reflective film according to the fifth embodiment of the present invention. [Figure 6] This is a three-dimensional shape profile image obtained by observing the surface shape of the anti-reflective film of Example 2 using a three-dimensional microscope. (a) is an image represented on a plane using a 256-level grayscale, and (b) is an image represented on a plane after binarization with a threshold of 40 nm from the reference plane. [Modes for carrying out the invention]

[0013] The present invention will now be described in detail. In this specification, unless otherwise specified, all physical properties refer to values ​​at room temperature and in air. In this specification, unless otherwise specified, the refractive index of a substance and a material layer refers to the refractive index at a measurement wavelength of 550 nm.

[0014] <Anti-reflective film of the first embodiment> (Overall composition of anti-reflective film) Figure 1 is a cross-sectional view of an anti-reflective film according to the first embodiment of the present invention. As shown in Figure 1, the anti-reflective film 10 according to the first embodiment of the present invention comprises a base film 12, a hard coat layer 14 formed on the surface of the base film 12, and a low refractive index layer 16 formed on the surface of the hard coat layer 14. In this embodiment, each of the above layers is laminated in order without any other layers in between. The low refractive index layer 16 is the outermost layer exposed on the surface of the anti-reflective film 10 as a whole. The low refractive index layer 16 is composed of a cured product of a composition containing a (meth)acrylate compound, hollow silica particles, and alumina particles surface-treated with a silane coupling agent, and has a predetermined uneven structure on its surface, which is described below.

[0015] (The uneven surface structure of the anti-reflective film) As will be explained in detail later, in the anti-reflective film 10 according to this embodiment, the low refractive index layer 16 contains alumina particles that function as protrusion-forming particles, thereby forming an uneven surface on the surface of the anti-reflective film 10. The uneven surface structure of the anti-reflective film 10 affects the wear resistance of the anti-reflective film 10. When the surface of the anti-reflective film 10 has an uneven surface, and a contact object that promotes surface wear, such as fingers operating a touch panel, touches the anti-reflective film 10, the pressure from the contact object is mainly concentrated on the protrusions of the uneven surface structure. This suppresses peeling of the surface layer in the recesses, and as a result, the overall wear resistance of the anti-reflective film 10 is thought to be improved. However, depending on the state of the uneven surface structure, the effect of improving wear resistance may not be sufficiently obtained. In addition, the uneven surface structure of the anti-reflective film 10 affects the transparency of the anti-reflective film 10. In the anti-reflective film 10 according to this embodiment, as will be explained below, if the skewness and kurtosis, which are parameters that reflect the shape and distribution of the protrusions, are within a predetermined range, the anti-reflective film 10 will have excellent wear resistance and high transparency (clarity).

[0016] The fine surface roughness distribution of the anti-reflective film 10 can be evaluated based on the three-dimensional surface roughness (surface shape profile) of the anti-reflective film 10. Three-dimensional surface roughness can be obtained, for example, by an optical wave field three-dimensional microscope (Otsuka Electronics, MINUK, etc.). While the measurement means for measuring three-dimensional surface roughness is not limited to an optical wave field three-dimensional microscope, when using an optical wave field three-dimensional microscope, the surface roughness is obtained using transmitted light through a transparent material. Unlike scanning white light interference microscopes or laser microscopes that utilize reflected light, this allows for highly accurate measurements even on the anti-reflective film 10, where the reflected light is very weak.

[0017] In the anti-reflective film 10 according to this embodiment, the kurtosis (Sku, sharpness) of the three-dimensional surface roughness of the surface is 5.0 or more and 11.0 or less. Sku is expressed by the following formula (1) and is a parameter that represents the sharpness of the height distribution of the unevenness. The larger the value of Sku, the sharper the height distribution. When Sku is 3, it indicates that the height values ​​on the surface follow a normal distribution, and when it exceeds 3, it indicates that there are many sharp peaks on the surface. In other words, if Sku is large and exceeds 3, the convex parts on the surface of the anti-reflective film 10 tend to support the pressure of contacting objects such as fingers at points, and even if surface wear progresses to a certain extent, it will continue to support contacting objects at points.

number

[0018] If the Sku is 5.0 or higher, the protrusions on the surface of the anti-reflective film 10 are sufficiently sharp to support the pressure of contacting objects such as fingers at a single point. This reduces the stress generated in the recesses, thereby suppressing wear of the anti-reflective film 10 as a whole. From the viewpoint of enhancing this effect, the Sku is preferably 6.0 or higher, and more preferably 7.5 or higher. On the other hand, if the Sku is 11.0 or lower, the state in which the protrusions protrude from the surface of the anti-reflective film 10 is stably maintained, so that the protrusions function stably as pillars that support contacting objects such as fingers, and the wear resistance can be effectively improved. From the viewpoint of enhancing this effect, the Sku is preferably 10.0 or lower, and more preferably 9.5 or lower.

[0019] Furthermore, in the anti-reflective film 10 according to this embodiment, the skewness (Ssk, bias, distortion) of the three-dimensional surface roughness of the surface is 1.00 or more and 1.14 or less. Ssk is expressed by the following equation (2) and is a parameter that represents the degree of symmetry in the height distribution of the unevenness, that is, whether the convex and concave parts are distributed symmetrically. The larger the value of Ssk in the positive direction, the more the unevenness structure is distributed biased towards the direction of lower height differences (the direction in which concave parts are dominant). In other words, the surface of the anti-reflective film 10 has relatively flat valleys, and the convex parts formed by the convex-forming particles contained in the low refractive index layer 16 exist as small peaks.

number

[0020] When Ssk is 1.00 or higher, the protrusions formed on the surface of the anti-reflective film 10 are sufficiently fine, and the area of ​​the valleys (areas that are less likely to be touched by fingers or other contact objects) is large and flat. As a result, wear is more easily suppressed for the anti-reflective film 10 as a whole, and high wear resistance is obtained. From the viewpoint of enhancing this effect, Ssk is preferably 1.02 or higher, and more preferably 1.05 or higher. On the other hand, when Ssk is 1.14 or lower, the decrease in transparency due to the presence of an excessive number of fine protrusions can be suppressed. From the viewpoint of enhancing this effect, Ssk is preferably 1.13 or lower, and more preferably 1.12 or lower.

[0021] Furthermore, in the anti-reflective film 10 according to this embodiment, it is preferable that the maximum peak height (Sp) in the three-dimensional surface roughness of the surface is 85 nm or more and 200 nm or less. If Sp is 85 nm or more, the protrusions will effectively function as pillars that support contact objects such as fingers, showing a high effect in improving and maintaining wear resistance. From the viewpoint of enhancing this effect, it is more preferable that Sp be 90 nm or more, and even more preferable that be 92 nm or more. On the other hand, if Sp is 200 nm or less, the anti-reflective film 10 tends to have high transparency. From the viewpoint of enhancing this effect, it is more preferable that Sp be 160 nm or less, and even more preferable that be 100 nm or less.

[0022] Furthermore, the arithmetic mean roughness (Sa) of the three-dimensional surface roughness of the surface of the anti-reflective film 10 is preferably in the range of 3.0 nm to 10 nm from the viewpoint of suppressing blocking (adhesion between the back surface and the front surface of the anti-reflective film 10). Sa is more preferably 3.5 nm or more, and even more preferably 4.0 nm or more. Also, Sa is more preferably 7.0 nm or less, and even more preferably 5.0 nm or less.

[0023] On the surface of the anti-reflective film 10, the density of protrusions having a height of 40 nm or more from the reference plane (average plane) is 1 mm 2 Preferably, there are between 100 and 300 protrusions per square meter. In the anti-reflective film 10, the density of protrusions having a height of 40 nm or more can be obtained, for example, by using a three-dimensional surface roughness profile obtained by a three-dimensional optical wave field microscope, etc., binarizing the height with a plane located 40 nm in the height direction from the reference plane as the threshold, and counting the number of locations having a height of 40 nm or more (white areas in the binarized image of the unevenness of the anti-reflective film surface shown in Figure 6(b)). 100 protrusions / mm² having a height of 40 nm or more 2 If the above conditions are met, the effect of suppressing wear on the recessed areas by receiving pressure from the contacting object with the convex areas will be enhanced. On the other hand, if the density is 300 pieces / mm 2If the following conditions are met, the antireflection film 10 will have excellent transparency. From the above perspective, the density of the convex portions is 130 per mm 2 per mm 2 or more, more preferably 150 per mm 2 or more, and even more preferably 260 per mm 2 or less, more preferably 230 per mm 2 or less, and even more preferably.

[0024] Also, on the surface of the antireflection film 10, the density of the convex portions having a height of 100 nm or more is preferably 5 or less per mm 2 per mm. The density of the convex portions having a height of 100 nm or more can be obtained in the same manner as above, by setting the threshold value to a plane located 100 nm in the height direction from the reference plane (average plane). If the number of the convex portions having a height of 100 nm or more is 5 or less per mm 2 the antireflection film 10 will have a small granular feeling and excellent transparency. To further enhance this effect, the number of the above convex portions is more preferably 4 or less per mm 2 even more preferably 2 or less per mm 2 and most preferably 0 per mm 2 piece.

[0025] As described above, in the antireflection film 10 according to the present embodiment, characteristics such as wear durability and transparency can be enhanced by parameters that reflect the shape and distribution of the irregularities in the three-dimensional surface roughness of the surface, including kurtosis and skewness. Those parameters can be controlled, for example, by the particle size, dispersibility (degree of secondary particle formation), addition amount, etc. of the alumina particles added to the low refractive index layer 16, which will be described in detail later.

[0026] In this embodiment, the uneven surface structure of the anti-reflective film 10 does not substantially contribute to the anti-reflective function. The anti-reflective function is brought about by the optical interference effect, but in this embodiment, by selecting elements such as the particle size, dispersibility, and amount of alumina particles in the low refractive index layer 16, the light diffusion effect (anti-glare) due to the uneven structure is substantially suppressed. Furthermore, the anti-reflective effect (moth-eye effect) caused by the gradual change in the refractive index of light as light passes between protrusions smaller than the wavelength of light formed on the surface is also substantially suppressed by selecting the above elements. The anti-reflective effect according to this embodiment is ensured solely by the low refractive index of the low refractive index layer 16 and the difference in refractive index between the low refractive index layer 16 and the hard coat layer 14.

[0027] (Base film) The base film 12 is not particularly limited as long as it is transparent. Examples of base film 12 include transparent polymer films and glass films. Transparency means that the total light transmittance in the visible light wavelength range is 50% or more, and more preferably 85% or more. The above 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 from the viewpoint of ease of handling, it is preferably in the range of 2 μm to 500 μm. More preferably it is in the range of 2 μm to 200 μm. In general, "film" refers to a material with a thickness of less than 0.25 mm, but even if the thickness is 0.25 mm or more, if it can be wound into a roll, it is also included as a "film".

[0028] 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.

[0029] 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.

[0030] (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 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. 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.

[0031] 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. From the viewpoint of improving curability, the curable composition more preferably contains polyfunctional (meth)acrylate as the (meth)acrylate.

[0032] 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. Specific examples of urethane (meth)acrylate 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, adduct-modified, and biuret-modified forms. Examples of hydroxyl group-containing (meth)acrylate compounds include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, trimethylolpropane diacrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and their polyoxyalkylene and polylactone modified forms. Examples of polyol compounds include ethylene glycol, propylene glycol, butanediol, hexanediol, polyoxyethylene glycol, polyoxypropylene glycol, glycerin, trimethylolpropane, pentaerythritol, biphenol, and bisphenol. 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 can be easily suppressed.

[0033] 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.

[0034] 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, inorganic particles, and resin particles. Additionally, solvents may be included as needed.

[0035] 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.

[0036] 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.

[0037] 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 curable composition. More preferably, it is 1% by mass or more and 5% by mass or less.

[0038] Inorganic particles and resin particles can be added to the hard coat layer 14 for purposes such as preventing blocking of the hard coat layer 14 or adjusting the refractive index of the hard coat layer 14. By adding inorganic particles and resin particles, fine surface irregularities are formed on the hard coat layer 14, which helps to suppress blocking between the front and back surfaces when the hard coat film, consisting of the base film 12 and the hard coat layer 14, is wound into a roll before the low refractive index layer 16 is formed.

[0039] Examples of inorganic particles that can adjust the refractive index of the hard coat layer 14 include metal oxide particles made from metal oxides such as titanium, zirconium, tin, zinc, silicon, niobium, aluminum, chromium, magnesium, germanium, gallium, antimony, and platinum. These may be used individually as optically adjustable inorganic particles, or in combination of two or more types. Among these, titanium oxide and zirconium oxide are particularly preferred from the viewpoint of achieving both high refractive index and transparency. Examples of resin particles include resin particles made from 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 individually as resin particles, or in combination of two or more types.

[0040] 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 inorganic particles or resin particles.

[0041] 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.

[0042] Solvents used in the curable composition for forming 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 individually or in combination of two or more.

[0043] The solid content concentration (concentration of components other than the solvent) of the curable composition should be determined appropriately, taking into consideration the coating properties, film thickness, etc. For example, it may be set to 1% to 90% by mass, 1.5% to 80% by mass, or 2% to 70% by mass.

[0044] (Low refractive index layer) In the anti-reflective film 10 according to this embodiment, a low refractive index layer 16 is provided on the surface of the hard coat layer 14 as an anti-reflective layer. The low refractive index layer 16 has a lower refractive index than the hard coat layer 14, and the difference in refractive index between the two layers produces an anti-reflective effect.

[0045] The low refractive index layer 16 is composed of a cured product of an ionizing radiation-curable composition containing a (meth)acrylate compound having a reactive group as a binder resin, alumina particles surface-treated with a silane coupling agent having a reactive group capable of bonding with the (meth)acrylate compound to form protrusions on the anti-reflective film 10, and hollow silica particles. As described above for the hard coat layer 14, ionizing radiation includes various electromagnetic waves and charged particle beams, but the low refractive index layer 16 is preferably composed of a cured product of an ultraviolet (UV) curable composition. Furthermore, the reactive groups contained in the (meth)acrylate compound and the silane coupling agent are preferably ultraviolet reactive. The preferred composition of the composition will be described below.

[0046] (1) (meth)acrylate compounds Examples of (meth)acrylate compounds having a reactive group include urethane (meth)acrylate, silicone (meth)acrylate, alkyl (meth)acrylate, and aryl (meth)acrylate. Furthermore, the (meth)acrylate compound may have only a (meth)acryloyl group as its reactive group, or it may have another reactive group in addition to the (meth)acryloyl group.

[0047] The (meth)acrylate may consist solely of monofunctional (meth)acrylates, solely of polyfunctional (meth)acrylates, or in combination of monofunctional (meth)acrylates and polyfunctional (meth)acrylates. It is more preferable for the (meth)acrylate to include polyfunctional (meth)acrylates.

[0048] 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.

[0049] 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.

[0050] The (meth)acrylate compound contained in the curable composition may consist of one type of (meth)acrylate as described above, or it may consist of two or more types. From the viewpoint of improving scratch resistance, the (meth)acrylate compound contained in the curable composition 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.

[0051] 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.

[0052] The content of the above-mentioned 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, from the viewpoint of scratch resistance, transparency, and solubility in solvents. More preferably, it is 30% by mass or more and 40% by mass or less.

[0053] (2) Fluorine-containing (meth)acrylate The curable composition constituting the low refractive index layer 16 preferably contains a fluorine-containing (meth)acrylate as part of the (meth)acrylate compound having a reactive group. This allows the anti-reflective film 10 to be given high anti-fouling properties. Specific examples of fluorine-containing (meth)acrylate include (meth)acrylate containing a perfluoropolyether group. A perfluoropolyether group refers to a polyether such as polyethylene glycol or polypropylene glycol in which all hydrogen atoms are replaced with fluorine. Examples include perfluoromethylene oxide (-CF2O-), perfluoroethylene oxide (-CF2CF2O-), perfluoropropylene oxide (-CF2CF2CF2O-), perfluoroisopropylene oxide (-CF(CF3)CF2O-), or a fluoropolyether group having a repeating structure formed by a combination of several of these. The number of repeating units in the above repeating structure is preferably 1 to 100. Specific examples of such compounds include Shin-Etsu Chemical's "KY-1203," "KY-1207," "KY-1211," "KY-1216," and "KY-1240," DIC's "Megafac RS-75," Daikin Industries' "Optool DAC-HP" and "Optool DAC-100," and Neos' "Futergent 601AD" and "Futergent 601ADH2." These fluorine-containing (meth)acrylates can suppress the adhesion of dirt and fingerprints, and make it easier to remove them.

[0054] It is preferable that the fluorine-containing (meth)acrylate does not have urethane bonds in its structure. The absence of urethane bonds in the fluorine-containing (meth)acrylate increases the hardness of the low refractive index layer 16, resulting in particularly high wear resistance for the low refractive index layer 16.

[0055] The content of fluorine-containing (meth)acrylate in the low refractive index layer 16 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 16. When the content of fluorine-containing (meth)acrylate in the low refractive index layer 16 is 1.0% by mass or more based on 100% by mass of the solid content of the low refractive index layer 16, the slipperiness of the surface of the low refractive index layer 16 is improved, and scratch resistance is improved. In addition, stain resistance is improved. From this viewpoint, the content of fluorine-containing (meth)acrylate in the low refractive index layer 16 is more preferably 3.0% by mass or more, and even more preferably 5.0% by mass or more, based on 100% by mass of the solid content of the low refractive index layer 16. Furthermore, when the content of fluorine-containing (meth)acrylate in the low refractive index layer 16 is 15.0% by mass or less based on 100% by mass of the solid content of the low refractive index layer 16, the decrease in scratch resistance is suppressed. Furthermore, from this perspective, the content of fluorine-containing (meth)acrylate in the low refractive index layer 16 is more preferably 13.0% by mass or less, and even more preferably 10.0% by mass or less, based on 100% by mass of the solid content of the low refractive index layer 16. The solid content of the low refractive index layer 16 as used herein refers to components that are not immobilized in the binder resin and are liquid at room temperature, excluding such components. The solid content of the low refractive index layer 16 includes alumina particles, hollow silica particles, and binder resin. It does not include oil components as additives or surfactants that are not immobilized in the binder resin.

[0056] (3) Alumina particles surface-treated with a silane coupling agent Alumina particles surface-treated with a silane coupling agent (hereinafter sometimes simply referred to as "alumina particles") are included in the low refractive index layer 16, thereby forming protrusions on the surface of the low refractive index layer 16. The formation of these protrusions on the surface of the low refractive index layer 16 by the alumina particles allows the low refractive index layer 16 to have good scratch resistance and wear resistance.

[0057] Alumina particles may be solid or hollow, but solid particles are preferred. Solid particles are particles that do not have substantially any voids inside, and the proportion of voids is less than 5% of the volume of the solid particle. Hollow particles are particles that have voids inside, and the proportion of voids is 5% or more of the volume of the hollow particle. When the alumina particles are solid, the scratch resistance of the low refractive index layer 16 is improved, and the scratch resistance of the anti-reflective film 10 is improved. On the other hand, when the alumina particles are hollow, the refractive index of the low refractive index layer 16 can be lowered, reducing light reflection. In the case of hollow particles, the proportion of voids is preferably 10% or more and 80% or less of the volume of the hollow particle. When the proportion of voids is 10% or more, the refractive index can be lowered, reducing light reflection. More preferably 20% or more, and even more preferably 30% or more. On the other hand, when the proportion of voids is 80% or less, the decrease in the dispersibility of the alumina particles can be suppressed. More preferably, it is 60% or less.

[0058] The shape of the alumina particles is not particularly limited and may be spherical, needle-shaped, flake-shaped, rod-shaped, fibrous, or irregular in shape. Of these, a spherical shape is preferred.

[0059] The alumina particles are surface-treated with a silane coupling agent having reactive groups capable of bonding with (meth)acrylate compounds. Because the silane coupling agent has reactive groups capable of bonding with (meth)acrylate compounds, the alumina particles surface-treated with the silane coupling agent can bond strongly with the (meth)acrylate contained in the low refractive index layer 16, and further bond with reactive groups contained in adjacent resin layers such as the hard coat layer 14. When these bonds are formed, the abrasion resistance and solvent resistance of the anti-reflective film 10 are improved.

[0060] Silane coupling agents generally have a hydrolyzable group and other functional groups bonded to a silicon atom in their molecule. Here, a hydrolyzable group is a substituent that is directly bonded to a silicon atom and can form a siloxane bond through hydrolysis and / or condensation reactions. Examples of hydrolyzable groups include halogen atoms, alkoxy groups, acyloxy groups, and alkenyloxy groups. When the hydrolyzable group has carbon atoms, the number of carbon atoms is preferably 6 or less, and more preferably 4 or less. In particular, alkoxy groups with 4 or fewer carbon atoms or alkenyloxy groups with 4 or fewer carbon atoms are preferred. The alumina particles are surface-treated when the hydrolyzable group undergoes hydrolysis and forms a bond with the oxygen atom on the surface of the alumina particles.

[0061] The silane coupling agent used here contains a reactive group capable of forming a bond with the (meth)acrylate compound, in addition to the hydrolyzable group mentioned above. Examples of reactive groups include carbon-carbon unsaturated double bond groups such as (meth)acryloyl groups, vinyl groups, styryl groups, and allyl groups, and ring-opening polymerizable groups such as epoxy groups and oxetanyl groups. These reactive groups are ultraviolet reactive. In the low refractive index layer 16 containing a (meth)acrylate compound having a reactive group and alumina particles surface-treated with a silane coupling agent having a reactive group, the reactive group of the (meth)acrylate compound and the reactive group of the silane coupling agent react to form a bond.

[0062] Examples of silane coupling agents having a carbon-carbon unsaturated double bond group as a reactive group include p-styryltrimethoxysilane, 2-(allyloxymethyl)acrylate (trimethoxysilyl)propyl, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 8-methacryloxyoctyltrimethoxysilane, p-styryltrimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, and 7-octenyltrimethoxysilane.

[0063] Examples of silane coupling agents having a ring-opening polymerizable group as a reactive group include 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, and 8-glycidoxyoctyltrimethoxysilane.

[0064] Of these, from the viewpoint of reactivity with (meth)acrylate compounds, it is preferable to use a silane coupling agent having a carbon-carbon unsaturated double bond group, and among these, silane coupling agents having ethylenically active carbon-carbon double bond groups such as (meth)acryloyl groups, vinyl groups, styryl groups, and allyl groups are particularly preferred.

[0065] The content of the silane coupling agent is preferably in the range of 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of alumina particles. This enhances the effect of the surface treatment by the silane coupling agent. Furthermore, it is possible to maintain high scratch resistance of the low refractive index layer 16 and improve wear durability and solvent resistance. More preferably, the content is 10 parts by mass or more and 40 parts by mass or less. Silane coupling agent that is not bound to the alumina particles may remain in the low refractive index layer 16, and the preferred content range described herein refers to the total content of the silane coupling agent, including the silane coupling agent that is not bound to the alumina particles.

[0066] From the viewpoint of enhancing the effect of forming protrusions on the surface of the low refractive index layer 16 by alumina particles surface-treated with a silane coupling agent and obtaining good wear resistance, it is preferable that the difference (D50-d) between the average particle diameter D50 in the volume-based cumulative particle size distribution of the alumina particles and the thickness d of the low refractive index layer 16 is 10 nm or more. More preferably, the difference (D50-d) is 20 nm or more, and even more preferably 30 nm or more. On the other hand, from the viewpoint of maintaining transparency by preventing the height of the formed protrusions from becoming excessively large, it is preferable that the difference (D50-d) is 200 nm or less. More preferably, it is 100 nm or less, and even more preferably 50 nm or less. In this specification, parameters related to particle diameter such as D10, D50, and D90 refer to values ​​in the volume-based cumulative particle size distribution. The volume-based cumulative particle size distribution can be obtained, for example, by dynamic light scattering. Furthermore, particle diameter includes not only the primary particle diameter but also the secondary particle diameter, which is the diameter of the particle aggregates. In other words, when particle aggregation occurs, the preferred values ​​for the particle size parameters apply not only to the particle size before aggregation but also to the particle size after aggregation. Furthermore, the particle size distribution of alumina particles can be evaluated by dispersing surface-treated alumina particles, which are used as raw materials when forming the low refractive index layer 16, in a solvent appropriately incorporated into the low refractive index layer forming composition. The particle size distribution evaluated in this way is substantially carried over as the particle size distribution of alumina particles in the low refractive index layer 16 that is actually formed. In this specification, the thickness d of the low refractive index layer 16 is the thickness of the relatively smooth portion in the thickness direction where there are no irregularities caused by alumina particles.

[0067] The average particle diameter D50 in the volume-based cumulative particle size distribution of alumina particles is preferably in the range of 60 nm to 200 nm, although this also depends on the thickness d of the low refractive index layer 16. More preferably it is 70 nm or more, and even more preferably 90 nm or more. Furthermore, it is more preferably 180 nm or less, and even more preferably 150 nm or less.

[0068] The 90% particle size D90 in the volume-based cumulative particle size distribution of alumina particles is preferably 300 nm or less. By keeping D90 below 300 nm, it is possible to effectively suppress the phenomenon in which large alumina particles form irregularities on the surface of the low refractive index layer 16, reducing smoothness and decreasing the scratch resistance and transparency of the anti-reflective film 10. D90 is preferably 280 nm or less, and more preferably 260 nm or less. On the other hand, the 90% particle size D90 of alumina particles is not particularly limited, but is preferably 100 nm or more. If D90 is 100 nm or more, it becomes easier to control D50 to 60 nm or more, making it easier to improve the scratch resistance and anti-reflective properties of the low refractive index layer 16. From this viewpoint, D90 is more preferably 150 nm or more, and even more preferably 180 nm or more.

[0069] Furthermore, the polydispersity index (PDI) of the alumina particles is preferably 0.8 or higher and 1.2 or lower when D90 is within the above range. The PDI can be evaluated using the average particle size D50, 90% particle size D90, and 10% particle size D10 by the following formula (3). PDI = (D90 - D10) / D50 (3)

[0070] The alumina particle content in the low refractive index layer 16 is preferably 0.1% by mass or more and 8.0% by mass or less based on 100% by mass of the solid content of the low refractive index layer 16. When the alumina particle content is within the above range, the skewness and curtsis in the low refractive index layer 16 are kept within the above preferred range while ensuring high transparency, making it easier to obtain good wear resistance. From this viewpoint, the alumina particle content is more preferably 1.0% by mass or more, even more preferably 2.0% by mass or more. Furthermore, it is more preferably 7.0% by mass or less, and even more preferably 6.0% by mass or less.

[0071] (4) Hollow silica particles Hollow silica particles are particles with an average particle diameter smaller than the average thickness d of the low refractive index layer 16. It is preferable that the hollow silica particles have an average particle diameter smaller than the alumina particles that form protrusions on the surface of the low refractive index layer 16. The hollow silica particles do not substantially contribute to the formation of surface irregularities in the low refractive index layer 16. Hollow silica particles are particles that have cavities inside, and the proportion of these cavities is 5% or more of their volume. "Hollow" refers to a shell structure consisting of an outer shell and internal cavities, or a porous structure with numerous cavities. The hollow structure of the hollow silica particles allows for a reduction in the refractive index of the low refractive index layer 16, 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. Among 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, effectively 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 depends on the thickness d of the low refractive index layer 16. 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 can be obtained in the low refractive index layer 16. 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 16 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 16. When the content of hollow silica particles in the low refractive index layer 16 is 6.0% by mass or more relative to 100% by mass of the solid content of the low refractive index layer 16, excellent anti-reflective 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 20% by mass or more, and particularly preferably 25% by mass or more, relative to 100% by mass of the solid content of the low refractive index layer 16. Furthermore, when the content of hollow silica particles in the low refractive index layer 16 is 49.9% by mass or less relative to 100% by mass of the solid content of the low refractive index layer 16, the decrease in scratch resistance can be 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, and even more preferably 40% by mass or less, relative to 100% by mass of the solid content of the low refractive index layer 16.

[0076] Furthermore, the total amount of alumina 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 relative to 100% by mass of the solid content of the low refractive index layer 16. If the total amount of alumina particles and hollow silica particles in the low refractive index layer 16 is 10% by mass or more relative to 100% by mass of the solid content of the low refractive index layer 16, excellent scratch resistance can be obtained. Also from this viewpoint, the total amount of alumina particles and hollow silica particles in the low refractive index layer 16 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 16. On the other hand, if the total amount of alumina particles and hollow silica particles in the low refractive index layer 16 is 50% by mass or less relative to 100% by mass of the solid content of the low refractive index layer 16, the alumina particles and hollow silica particles can be sufficiently retained in the low refractive index layer 16, thus excellent scratch resistance can be obtained. Furthermore, from this viewpoint, the total amount of alumina particles and hollow silica particles in the low refractive index layer 16 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 16.

[0077] As described above, the low refractive index layer 16 is formed using an ionizing radiation-curable composition containing a (meth)acrylate compound having a reactive group, alumina particles surface-treated with a silane coupling agent having a reactive group capable of bonding with the (meth)acrylate compound, and hollow silica particles. In the low refractive index layer 16, after irradiation with ionizing radiation, bonds are formed between the (meth)acrylate compounds themselves, between the surface-treated alumina particles themselves, between the (meth)acrylate compounds and the surface-treated alumina particles, and between the (meth)acrylate compounds and the surface-treated alumina particles and the reactive groups contained in adjacent layers, via the reactive groups, thereby giving the low refractive index layer 16 high scratch resistance, abrasion resistance, and solvent resistance. As described above, the reactive groups contained in the (meth)acrylate compound and the silane coupling agent are preferably ultraviolet reactive. When the (meth)acrylate compound and alumina particles have UV-reactive reactive groups, UV irradiation of the low refractive index layer 16 formed from a composition containing the (meth)acrylate compound and surface-treated alumina particles improves the scratch resistance, abrasion resistance and solvent resistance of the low refractive index layer 16, thereby improving the scratch resistance, abrasion resistance and solvent resistance of the anti-reflective film 10.

[0078] (5) Other ingredients The composition for forming the low refractive index layer 16 preferably further contains a photopolymerization initiator if the (meth)acrylate compound has an ultraviolet-reactive group (i.e., it is an ultraviolet-curable resin). As the photopolymerization initiator, the photopolymerization initiators 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.

[0079] In compositions for forming a low refractive index layer, the alumina particles are typically prepared as a high-concentration particle dispersion (slurry), diluted with a solvent or the like immediately before the coating process, and mixed with other materials such as a binder resin. Because the alumina particles are surface-treated with a silane coupling agent, even if alumina particles with a predetermined particle size (primary particle size) are used, there is a risk that the alumina particles may re-aggregate or self-crosslink during the various material compounding processes before coating the low refractive index layer-forming composition to form the low refractive index layer 16, or during storage in a container. To suppress these phenomena, it is desirable to maintain a state in which the alumina particles are uniformly dispersed in the composition. One method to suppress the re-aggregation and self-crosslinking of alumina particles is to use a solvent with a predetermined viscosity and predetermined solubility parameters (SP value) as the solvent used when preparing the low refractive index layer-forming composition. By appropriately selecting the solvent in this way, the re-aggregation and self-crosslinking of alumina particles can be suppressed.

[0080] Specifically, it is preferable that the viscosity of the solvent contained in the low refractive index layer-forming composition is within the range of 2.0 mPa·s to 4.0 mPa·s. More preferably, the viscosity of the solvent is 2.1 mPa·s or higher, and 3.0 mPa·s or lower. If the viscosity of the solvent is 2.0 mPa·s or higher, it is possible to effectively prevent the re-aggregation and self-crosslinking of alumina particles. On the other hand, if the viscosity of the solvent is 4.0 mPa·s or lower, the viscosity of the low refractive index layer-forming composition can be kept low, making it less likely for defects such as streaks and horizontal unevenness to occur on the surface of the low refractive index layer 16 during the coating process. The viscosity of the solvent can be measured, for example, with a coaxial double-cylinder rotational viscometer in accordance with JIS Z8803:2011.

[0081] Examples of solvents having a viscosity of 2.0 mPa·s or more and 4.0 mPa·s or less include tetraethylene glycol dimethyl ether (3.8 mPa·s), diethylene glycol dibutyl ether (2.4 mPa·s), triethylene glycol butyl methyl ether (2.9 mPa·s), tripropylene glycol dimethyl ether (2.3 mPa·s), cyclohexanone (2.3 mPa·s), isopropyl alcohol (2.4 mPa·s), n-butanol (2.5 mPa·s), and dimethyl sulfoxide (2.0 mPa·s).

[0082] Furthermore, the solubility parameter of the solvent to be included in the low refractive index layer forming composition is 8.0 (cal / cm²). 3 ) 1 / 2 More than 11.0((cal / cm 3 ) 1 / 2 The following range is preferable: The solubility parameter is 9.0 (cal / cm³). 3 ) 1 / 2 That's all, also 10.0 ((cal / cm 3 ) 1 / 2 The following is more preferable: By keeping the dissolution parameter within the above range, a good dispersion state of alumina particles can be maintained, and materials other than particles, such as binder resins, used in low refractive index forming compositions can be sufficiently dissolved. In this specification, the dissolution parameter is represented by the Hildebrand dissolution parameter δ. The Hildebrand dissolution parameter δ is calculated by the following formula (4), and is a physical property value defined as the square root of the cohesive energy density, serving as an indicator of the solvent's dissolution behavior. δ = [(ΔH - RT) / V] 1 / 2 (4) In equation (4), ΔH represents the latent heat of vaporization, R is the gas constant, T is the temperature, and V is the molecular volume.

[0083] 8.0 ((cal / cm) 3 ) 1 / 2 More than 11.0((cal / cm 3 ) 1 / 2 Solvents having the following solubility parameters include, for example, diethylene glycol monobutyl ether (10.2 (cal / cm³)3 ) 1 / 2 ), propylene glycol monomethyl ether (10.1 (cal / cm³) 3 ) 1 / 2 ), methyl ethyl ketone (9.3 (cal / cm³) 3 ) 1 / 2 ), methyl isobutyl ketone (8.4 (cal / cm³) 3 ) 1 / 2 ), cyclohexanone (9.9 (cal / cm³) 3 ) 1 / 2 ), Toluene (8.9 (cal / cm³) 3 ) 1 / 2 ), xylene (8.8 (cal / cm³) 3 ) 1 / 2 ) Ethyl acetate (9.1 (cal / cm³) 3 ) 1 / 2 ), butyl acetate (8.5 (cal / cm³) 3 ) 1 / 2 ), acetone (9.9 (cal / cm³) 3 ) 1 / 2 ) are some examples.

[0084] The solvent preferably satisfies at least one of the viscosity and solubility parameters within the predetermined range described above, and more preferably satisfies both simultaneously. Cyclohexanone is suitably used as a solvent that simultaneously satisfies the viscosity and solubility parameters within the predetermined range described above. The solvent may be used alone or in combination of two or more types. When combining two or more solvents, the solvents to be combined may be selected from the solvents listed above, or the solvents listed above may be combined with other solvents. As for other solvents, for example, they may be appropriately selected from the various solvents exemplified as solvents used in hard coat layer forming compositions. However, even when solvents are mixed and used, it is preferable that at least one, preferably both, of the viscosity and solubility parameters of the mixed solvent be within the above range.

[0085] In a composition for forming a low refractive index layer, the amount of solvent added can be set, for example, so that the solid content concentration in the composition is 1% by mass or more and 20% by mass or less. This allows for the efficient formation of a low refractive index layer 16 with the required thickness, and also significantly enhances the effect of using a solvent having the above-mentioned predetermined physical properties.

[0086] The binder resin of the low refractive index layer 16 may consist solely of an ultraviolet-curable resin such as (meth)acrylic resin, or it may consist of a combination of an ultraviolet-curable resin and a non-ultraviolet-curable resin. As the non-ultraviolet-curable resin, the resins 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.

[0087] In addition, the low refractive index layer 16 may contain additives as needed. Examples of such additives include dispersants, leveling agents, defoamers, vibration modifiers, antibacterial agents, flame retardants, slip agents, refractive index adjusters, inorganic particles other than alumina particles, and resin particles. If inorganic particles other than alumina particles are included, these inorganic particles may also be surface-treated with a silane coupling agent having a reactive group capable of bonding with (meth)acrylate compounds, similar to the alumina particles.

[0088] (6) Characteristics of the low refractive index layer In this embodiment, it is preferable that the water contact angle of the surface of the anti-reflective film 10, that is, the surface of the low refractive index layer 16, is 100° or more. This gives the anti-reflective film 10 high stain resistance. In addition, the slipperiness of the surface of the low refractive index layer 16 is improved, which contributes to improved scratch resistance. From the viewpoint of obtaining even higher stain resistance, the water contact angle of the surface of the low refractive index layer 16 is more preferably 105° or more, and even more preferably 110° or more. The water contact angle of the surface of the low refractive index layer 16 depends on the component composition of the constituent material of the low refractive index layer 16. For example, by including fluorine-containing (meth)acrylate or silicone-containing (meth)acrylate in the low refractive index layer 16, the water contact angle can be increased. In addition, the water contact angle of the surface of the low refractive index layer 16 can also be increased by providing fine irregularities on the surface of the low refractive index layer 16, and in this embodiment, alumina particles contained in the low refractive index layer 16 can play this role. However, imparting irregularities to the surface of the low refractive index layer 16 may reduce the wipeability of the surface. From the viewpoint of reducing this possibility, it is preferable to increase the water contact angle by adding fluorine-containing (meth)acrylate or silicone-containing (meth)acrylate in addition to imparting moderate irregularities that satisfy the predetermined skewness and kurtosis, rather than by imparting excessive irregularities. There is no particular upper limit set for the water contact angle of the surface of the low refractive index layer 16, but it is generally 130° or less.

[0089] 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 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 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.

[0090] The average thickness d of the low refractive index layer 16 is preferably in the range of 80 nm to 110 nm. More preferably it is 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.

[0091] (Method of manufacturing anti-reflective film) To manufacture the anti-reflective film 10, a hard coat layer 14 and a low refractive index layer 16 can be formed in this order on the surface of a base film 12. To form each layer, the composition for forming each layer is applied, and after drying as necessary, it is cured by a method appropriate to the curability of the composition, such as irradiation with ionizing radiation including ultraviolet light. After forming one layer, the composition for forming the next layer is applied, and after drying as necessary, the composition is cured. By repeating this process sequentially, a laminated structure of hard coat layers 14 and low refractive index layers 16 can be formed, and the anti-reflective film 10 can be manufactured.

[0092] A wet method can be suitably used for coating 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, offset printing, screen printing, and flexographic printing, can be used.

[0093] The drying process for each layer is not particularly limited as long as it removes the solvents 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.

[0094] 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.

[0095] 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.

[0096] (Characteristics of anti-reflective film) As described above, the anti-reflective film 10 according to this embodiment has a hard coat layer 14 and a low refractive index layer 16 on the surface of a base film 12 in that order. The low refractive index layer is composed of a cured product of an ionizing radiation-curable composition containing a (meth)acrylate compound having a reactive group, alumina particles surface-treated with a silane coupling agent having a reactive group capable of bonding with the (meth)acrylate compound, and hollow silica particles. Bonds are formed between the reactive groups contained in the surface treatment agent of the alumina particles contained in the low refractive index layer 16 and the (meth)acrylate compound as a binder resin, thereby giving the low refractive index layer 16 high scratch resistance, abrasion resistance, and solvent resistance. Furthermore, on the surface of the anti-reflective film 10, the distribution of the uneven structure is controlled so that the skewness in the three-dimensional surface roughness is 1.00 or more and 1.14 or less, and the crustosis is 5.0 or more and 11.0 or less, thereby effectively increasing abrasion resistance and maintaining high transparency of the anti-reflective film 10. Because the anti-reflective film 10 has high abrasion resistance, it is easier to maintain the properties inherent to the surface of the anti-reflective film 10, such as high stain resistance and solvent resistance, even after repeated contact with objects such as fingers.

[0097] The haze in the anti-reflective film 10 is preferably 2.0 or less, more preferably 1.5 or less, and even more preferably 1.0 or less, from the viewpoint of good transparency and other factors. The luminous reflectance of the anti-reflective film 10 is preferably as low as possible, 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-reflective film 10 can be considered to have sufficiently high anti-reflective properties.

[0098] <Anti-reflective film of the 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 has a base film 12, a hard coat layer 14 formed on the surface of the base film 12, a low refractive index layer 16 formed on the surface of the hard coat layer 14, and an anti-fouling layer 18 formed on the surface of the low refractive index layer 16.

[0099] 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 an anti-fouling layer 18 on the surface of the low refractive index layer 16. Other than this, 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. In the anti-reflective film 10 according to the first embodiment, predetermined parameters related to the uneven surface structure were obtained on the surface of the low refractive index layer 16, which is the surface of the entire anti-reflective film 10, such as a skewness (Ssk) of 1.00 or more and 1.14 or less in three-dimensional surface roughness, and a crustosis (Sku) of 5.0 or more and 11.0 or less. In the anti-reflective film 20 according to the second embodiment, parameters related to the uneven surface structure are obtained on the surface of the anti-fouling layer 18, which is the surface of the entire anti-reflective film 20, such as a skewness (Ssk) of 1.00 or more and 1.14 or less in three-dimensional surface roughness, and a crustosis (Sku) of 5.0 or more and 11.0 or less.

[0100] (Anti-fouling layer) In the anti-reflective film 20 according to this embodiment, an anti-fouling layer 18 is provided on the surface of the low refractive index layer 16. The anti-fouling layer 18 enhances the anti-fouling properties of the anti-reflective film 20.

[0101] The antifouling layer 18 is composed of a cured product of an ionizing radiation-curable composition containing fluorine-containing (meth)acrylate. In particular, it is preferable that it be composed of a cured product of an ultraviolet-curable composition.

[0102] The antifouling layer 18 is composed of a cured product of a composition containing fluorine-containing (meth)acrylate, so that the anti-reflective film 20 having the antifouling layer 18 on its surface has excellent antifouling properties, solvent resistance, abrasion resistance, and scratch resistance. Specific examples of fluorine-containing (meth)acrylate include (meth)acrylate containing perfluoropolyether groups. A perfluoropolyether group refers to a polyether such as polyethylene glycol or polypropylene glycol in which all hydrogen atoms are replaced with fluorine. Examples include perfluoromethylene oxide (-CF2O-), perfluoroethylene oxide (-CF2CF2O-), perfluoropropylene oxide (-CF2CF2CF2O-), perfluoroisopropylene oxide (-CF(CF3)CF2O-), or a fluoropolyether group having a repeating structure formed by a combination of several of these. The number of repeating units in the above repeating structure is preferably 1 to 100. Specific examples of compounds include "KY-1203," "KY-1207," "KY-1211," "KY-1216," and "KY-1240" from Shin-Etsu Chemical Co., Ltd., "Megafac RS-75" from DIC Corporation, "Optool DAC-HP" and "Optool DAC-100" from Daikin Industries, Ltd., and "Futergent 601AD" and "Futergent 601ADH2" from Neos Co., Ltd.

[0103] It is preferable that the fluorine-containing (meth)acrylate does not have urethane bonds in its structure. By the absence of urethane bonds in the structure of the fluorine-containing (meth)acrylate, the hardness of the antifouling layer 18 is increased, and the antifouling layer 18 is given particularly high abrasion resistance.

[0104] In the antifouling layer 18, it is preferable that the content of fluorine-containing (meth)acrylate is 90% by mass or more based on the total solid content of the antifouling layer 18. This allows for a high level of antifouling improvement effect due to fluorine-containing (meth)acrylate. From the viewpoint of further enhancing the antifouling improvement effect, it is even more preferable that the content of 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. Furthermore, it is even more preferable that the entire amount of resin components constituting the antifouling layer 18, excluding unavoidable components, is fluorine-containing (meth)acrylate. The solid content of the antifouling layer 18 as used herein refers to components that are not fixed in the curable component of the antifouling layer 18 and exclude components that are liquid at room temperature. The solid content of the antifouling layer 18 includes fluorine-containing (meth)acrylate, etc.

[0105] The antifouling layer 18 can be formed using a composition containing fluorine-containing (meth)acrylate. The composition for forming the antifouling layer 18 can be arranged in layers on the surface of the low refractive index layer 16 and then cured. When the antifouling layer 18 is formed as a cured product of a composition having UV curability, the composition for forming the antifouling layer 18 preferably further contains a photopolymerization initiator. It may also contain a solvent as needed.

[0106] As the photopolymerization initiator and 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 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.

[0107] In addition, the antifouling layer 18 may contain additives as needed. Examples of such additives include antifouling agents other than fluorine-containing (meth)acrylate, dispersants, leveling agents, defoamers, vibration modifiers, antibacterial agents, flame retardants, slip agents, and refractive index modifiers. However, from the viewpoint of improving the surface smoothness of the antifouling layer 18, it is preferable that the antifouling layer 18 does not contain solid particles, including metal oxide particles such as alumina particles and hollow silica particles. Even if the antifouling layer 18 contains solid particles, it is preferable to keep the particle size of the solid particles to 10 nm or less, and the solid particle content to 1% by mass or less relative to 100% by mass of the solid content of the antifouling layer 18.

[0108] In this embodiment, it is preferable that the water contact angle of the surface of the anti-reflective film 20, that is, the surface of the anti-fouling layer 18, is 100° or more. This gives the anti-reflective film 20 high anti-fouling properties. In addition, the slipperiness of the surface of the anti-fouling layer 18 is improved, which contributes to improved scratch resistance. From the viewpoint of obtaining even higher anti-fouling properties, the water contact angle of the surface of the anti-fouling layer 18 is more preferably 105° or more, and even more preferably 110° or more. The water contact angle of the surface of the anti-fouling layer 18 can be increased, for example, by increasing the content of fluorine-containing (meth)acrylate in the anti-fouling layer 18. There is no particular upper limit set for the water contact angle of the surface of the anti-fouling layer 18, but it is generally 130° or less.

[0109] The thickness of the antifouling layer 18 is preferably 1 nm or more. This allows for a high improvement in antifouling properties. More preferably, the thickness of the antifouling layer 18 is 3 nm or more, and even more preferably 5 nm or more. On the other hand, the thickness of the antifouling layer 18 is preferably 15 nm or less. This allows for a high level of anti-reflective properties of the anti-reflective film 20. More preferably, the thickness of the antifouling layer 18 is 10 nm or less.

[0110] The refractive index of the antifouling layer 18 is preferably 1.6 or less. If it is 1.6 or less, the anti-reflective properties of the anti-reflective film 20 can be kept high. More preferably, the refractive index of the antifouling layer 18 is 1.55 or less, and even more preferably 1.50 or less. On the other hand, the refractive index of the antifouling layer 18 is not particularly limited as long as the thickness of the antifouling layer 18 is within the above range, but it is preferably 1.3 or more, and more preferably 1.35 or more.

[0111] In the anti-reflective film 20 according to this embodiment, the composition of the low refractive index layer 16 may be the same as the composition of the anti-reflective film 10 according to the first embodiment. However, unlike the anti-reflective film 10 according to the first embodiment, an anti-fouling layer 18 is provided on the low refractive index layer 16, and the anti-fouling layer 18 exhibits high anti-fouling properties. Therefore, it is not necessary to include a fluorine-containing compound in the low refractive index layer 16 for the purpose of improving anti-fouling properties. If a large amount of fluorine-containing compound is included in the low refractive index layer 16, the wettability between it and the composition for forming the anti-fouling layer 18 will decrease, weakening the adhesion with the anti-fouling layer 18 and leading to a decrease in the scratch resistance of the anti-reflective film 20. However, by keeping the low refractive index layer 16 free of fluorine-containing compounds, the scratch resistance of the anti-reflective film 20 can be improved. Even when a fluorine-containing compound is included in the low refractive index layer 16, it is preferable to keep its content at 1% by mass or less per 100% by mass of the solid content of the low refractive index layer 16.

[0112] In the anti-reflective film 20 according to this embodiment, an anti-fouling layer 18 is provided in direct contact with the surface of the low refractive index layer 16. For example, no primer layer having an adhesion-improving effect, such as a layer made of fluorine-free (meth)acrylate resin, is formed on the surface of the low refractive index layer 16. By not providing such a primer layer, the structure of the anti-reflective film 20 is simplified, and the productivity and cost reduction effects of the anti-reflective film 20 can be enhanced.

[0113] <Other forms of anti-reflective film> As described above, the anti-reflective film according to the present invention has a hard coat layer 14 and a low refractive index layer 16 laminated in that order on the surface of a base film 12, and optionally an anti-fouling layer 18 laminated thereon. The configuration is not limited to the anti-reflective film 10 according to the first embodiment or the anti-reflective film 20 according to the second embodiment, as long as the low refractive index layer 16 has a predetermined composition. Other embodiments of the anti-reflective film according to the present invention are illustrated below.

[0114] (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 the surface of the base film 12, a high refractive index layer 15 formed on the surface of the hard coat layer 14, and a low refractive index layer 16 formed on the surface of the high refractive index layer 15.

[0115] The anti-reflective film 30 according to the third embodiment differs from the anti-reflective 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 the same as the anti-reflective film 10 according to the first embodiment, and a description of the similar configuration will be omitted.

[0116] 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, a high anti-reflective effect is achieved in the anti-reflective film 30. The refractive index of the high refractive index layer 15 is preferably in the range of 1.55 to 1.80. More preferably it is 1.60 or higher, and 1.70 or lower.

[0117] The constituent materials of the high refractive index layer 15 are not particularly limited, and any known materials conventionally used in anti-reflective films, etc., can be used to obtain a predetermined refractive index. For example, materials can be appropriately selected from the materials described above that can be used in the hard coat layer 14 and the low refractive index layer 16. The refractive index of the high refractive index layer 15 can be adjusted by selecting and blending binder resin, inorganic oxide particles, resin particles, etc. For example, by adding a sufficient amount of inorganic oxide particles, a high refractive index layer 15 with a refractive index higher than that of the low refractive index layer 16 can be formed.

[0118] The average thickness of the high refractive index layer 15 varies depending on the refractive index setting, but for example, setting it to 50 nm to 200 nm can further enhance the anti-reflective function. The high refractive index layer 15 may be provided by stacking two or more layers with mutually different refractive indices.

[0119] (Fourth embodiment) Figure 4 shows an anti-reflective film 40 according to the fourth embodiment. The anti-reflective film 40 according to the fourth embodiment has a base film 12, a hard coat layer 14 formed on one surface of the base film 12, and a low refractive index layer 16 formed on the surface of the hard coat layer 14. 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 40 and is peeled off from the transparent adhesive layer 22 when the anti-reflective film 40 is used.

[0120] The anti-reflective film 40 according to the fourth 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.

[0121] The transparent adhesive layer 22 is for ensuring good adhesion of the anti-reflective film 40 to the surface of a display or the like. Furthermore, the presence of the transparent adhesive layer 22 of the anti-reflective film 40 has the effect of preventing the glass of the display or the like from shattering. In other words, the anti-reflective film 40 also functions as a shatterproof film.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] (Fifth embodiment) Figure 5 shows an anti-reflective film 50 according to the fifth embodiment. The anti-reflective film 50 according to the fifth embodiment includes a base film 12, a hard coat layer 14 formed on one surface of the base film 12, a low refractive index layer 16 formed on the surface of the hard coat layer 14, and a protective film 28 disposed on the surface of the low refractive index layer 16 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.

[0128] The anti-reflective film 50 according to the fifth embodiment differs from the anti-reflective film 40 according to the fourth embodiment in that it has a protective film 28 on the surface of the low refractive index layer 16 via an adhesive layer 26. Otherwise, it is the same as the anti-reflective film 40 according to the fourth embodiment, and a description of the similar configuration will be omitted.

[0129] The protective film 28 can prevent scratches on the surface of the low refractive index layer 16 when handling the anti-reflective film 50, 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 16 via an adhesive layer 26. After processing of the anti-reflective film 50, the protective film 28 is peeled off from the surface of the low refractive index layer 16 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 16 and the adhesive layer 26, and the adhesive force is adjusted to allow for interfacial peeling between the low refractive index layer 16 and the adhesive layer 26. In the anti-reflective film 50 according to this embodiment, parameters related to the surface unevenness structure, such as skewness and kurtosis, and various parameters mentioned above regarding the surface characteristics of the anti-reflective film, such as the water contact angle, are defined for the surface in the state after the protective film 28 and adhesive layer 26 have been peeled off.

[0130] 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, preferably in the range of 2 μm to 200 μm.

[0131] 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.

[0132] (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.

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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. Furthermore, various functional layers such as a gas barrier-improving layer, an antistatic layer, and an oligomer-blocking layer may be pre-applied to the surface of the base film 12 before each layer is formed. As the antistatic layer, the one described in Patent Document 1 can be suitably applied.

[0138] In the third embodiment described above, the high refractive index layer 15 is shown as an addition to the anti-reflective film 10 of the first embodiment shown in Figure 1, as shown in Figure 3, but it may also be added to the anti-reflective film 20 of the second embodiment shown in Figure 2. Furthermore, in the fourth embodiment described above, the transparent adhesive layer 22 and release film 24 are shown as an addition to the anti-reflective film 10 of the first embodiment shown in Figure 1, as shown in Figure 4, but they may also be added to the anti-reflective film 20 of the second embodiment shown in Figure 2 or the anti-reflective film 30 of the third embodiment shown in Figure 3. In addition, in the fifth embodiment described above, the adhesive layer 26 and protective film 28 are shown as an addition to the anti-reflective film 40 of the fourth embodiment shown in Figure 4, as shown in Figure 5, but they may also be added to the anti-reflective film 10 of the first embodiment shown in Figure 1 or the anti-reflective film 20 of the second embodiment shown in Figure 2, or to the anti-reflective film 30 of the third embodiment shown in Figure 3. In the case where an adhesive layer 26 and a protective film 28 are added to the anti-reflective film 20 of the second embodiment, the adhesive force between the protective film 28 and the adhesive layer 26 is stronger than the adhesive force between the anti-fouling layer 18 and the adhesive layer 26, and the adhesive force between the anti-fouling layer 18 and the adhesive layer 26 is adjusted to allow for interfacial peeling. [Examples]

[0139] 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.

[0140] <Preparation of compositions for forming a hard coat layer> To the UV-curable resin composition "ESS-620" (manufactured by DIC; urethane acrylate resin, solvent (ethyl acetate); solid content concentration 79% by mass), the photopolymerization initiator "Omnirad127" (manufactured by IGM Resins BV) was added to a total solid content of 3% by mass relative to the total solid content of the hard coat layer forming composition. Furthermore, ethyl acetate was added to a solid content concentration of 31% by mass to prepare the hard coat layer forming composition.

[0141] <Preparation of compositions for forming high refractive index layers> A composition for forming a high refractive index layer was prepared by adding methyl ethyl ketone to the UV-curable resin composition "TYZ65-01" (manufactured by Toyo Chem; acrylic resin, zirconium oxide (average particle size 80 nm), photopolymerization initiator (the above "Omnirad127"), solvent (cyclohexanone, methyl isobutyl ketone, propylene glycol monomethyl ether); solid content concentration 35% by mass) to a solid content concentration of 8% by mass.

[0142] <Preparation of alumina particles surface-treated with a silane coupling agent containing reactive groups> In a 500ml stainless steel pot, 25g of untreated alumina particles (average particle size 160nm), 2.5g of a silane coupling agent (Shin-Etsu Chemical Co., Ltd. "KBM-5103", 3-acryloxypropyltrimethoxysilane), and 72.5g of propylene glycol monomethyl ether were added. The mixture was then mixed and dispersed using a homomixer (Primix Corporation "Homomixer MARK II 2.5") at 4000rpm for 30 minutes to obtain a dispersion of alumina particles surface-treated with a silane coupling agent having an acryloyl group as a reactive group.

[0143] <Preparation of a composition for forming a low refractive index layer> A composition for forming a low refractive index layer was prepared by blending a binder resin, hollow silica particles, alumina particles, fluorine-containing (meth)acrylate, and a photopolymerization initiator to the composition shown in Table 1 (mass %), and adjusting the solid content concentration to the level shown in Table 1 using the solvent shown in Table 1.

[0144] The materials used as components for the low refractive index layer formation composition are as follows: (Except for solvents) • Binder resin: "Aronics MT-3041" manufactured by Toagosei; polyfunctional acrylate; solids content concentration 100% by mass • Hollow silica particles: JGC Catalysts & Chemicals "Thru-Ria 4320"; average particle size 60 nm; solvent: MIBK; solids content concentration 20% by mass • Alumina particles: The above-mentioned dispersion of alumina particles • Fluorine-containing compound: "KY-1216" manufactured by Shin-Etsu Chemical Co., Ltd.; perfluoropolyether group-containing (meth)acrylate, methyl ethyl ketone; solid content concentration 20% by mass (used in Examples 1-3 and Comparative Examples 1-6) • Photopolymerization initiator: "Omnirad127" as described above. (solvent) CHX: Cyclohexanone (SP value: 9.9 (cal / cm³) 3 ) 1 / 2 , viscosity (20℃): 2.3mPa s) MIBK: Methyl isobutyl ketone (SP value: 8.4 (cal / cm³) 3 ) 1 / 2 , viscosity (20℃): 0.6mPa s) MEK: Methyl ethyl ketone (SP value: 9.3 (cal / cm³) 3 ) 1 / 2 , viscosity (20℃): 0.4mPa·s) • PGM: Propylene glycol monomethyl ether (SP value: 10.1 (cal / cm³) 3 ) 1 / 2 , viscosity (20℃): 1.9mPa s) IPA: Isopropyl alcohol (SP value: 11.9 (cal / cm³) 3 ) 1 / 2 , viscosity (20℃): 2.4mPa s) • TOL: Toluene (SP value: 8.9 (cal / cm³) 3 ) 1 / 2 , viscosity (20℃): 0.6mPa s)

[0145] <Preparation of composition for forming an antifouling layer> A fluorine-containing compound ("KY-1216") was mixed with a photopolymerization initiator ("Omnirad127") to a concentration of 7% by mass relative to the total solid content of the antifouling layer-forming composition. Furthermore, a solvent (MEK / butyl acetate = 1 / 1) was added to achieve a solid content concentration of 0.3% by mass to prepare the antifouling layer-forming composition.

[0146] <Preparation of the hard coat layer> For each of Examples 1-4 and Comparative Examples 1-6, a hard coat layer-forming composition was applied to a base film (Toray Industries' "Lumirror #50-U403", polyethylene terephthalate film, 50 μm thick) using a #12 wire bar. After drying at 80°C for 60 seconds, a high-pressure mercury lamp was used to apply light at a intensity of 200 mJ / cm². 2 A hard coat layer (thickness 4 μm) was formed by irradiating it with ultraviolet light.

[0147] <Fabrication of high refractive index layers> For each of Examples 1-4 and Comparative Examples 1-6, a high refractive index layer-forming composition was applied to the surface of the hard coat layer, dried at 80°C for 60 seconds, and then exposed to light at a pressure of 200 mJ / cm² using a high-pressure mercury lamp under a nitrogen atmosphere. 2 A high refractive index layer (thickness 110 nm) was formed by irradiating it with ultraviolet light.

[0148] <Fabrication of low refractive index layers> For each of Examples 1-4 and Comparative Examples 1-6, 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 100°C for 60 seconds, and then exposed to light at a pressure of 200 mJ / cm² using a high-pressure mercury lamp under a nitrogen atmosphere. 2 A low refractive index layer was formed by irradiating with ultraviolet light. The thickness was as shown in Table 1.

[0149] <Preparation of antifouling layer> In Example 4, the antifouling layer-forming composition was applied to the surface of the low refractive index layer using a #3 wire bar, dried at 100°C for 60 seconds, and then exposed to light at a pressure of 200 mJ / cm² using a high-pressure mercury lamp under a nitrogen atmosphere. 2 A stain-resistant layer was formed by irradiating it with ultraviolet light. The thickness was set to 5 nm.

[0150] <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, low refractive index layer, and anti-fouling layer (Example 4 only) were evaluated. In this process, for each layer formed, the thickness and refractive index at 550 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. Note that the thickness of the low refractive index layer in Comparative Examples 1 and 2 was not evaluated because the reflected light diffused, preventing a sufficient signal from being obtained to measure the film thickness.

[0151] (Particle size distribution of alumina particles) The alumina particle dispersion prepared above was blended with the solvents listed in Table 1 (alumina particle concentration 0.14 mass%). Using a nanoparticle size measurement system (Otsuka Electronics "nanoSAQLA"), the average particle size (D50), cumulative 90% particle size (D90), and cumulative 10% particle size (D10) were measured by dynamic light scattering, based on volume. In addition, the polydispersity index (PDI) of the alumina particles was calculated according to equation (3) shown below. PDI = (D90 - D10) / D50 (3)

[0152] (Haze (Hz)) The haze (Hz) of the entire anti-reflective film was measured using the "Haze Meter NDH7000" manufactured by Nippon Denshoku Industries, according to the JIS-K7136 method. A haze of 2.0 or less indicates high transparency.

[0153] (Abrasion durability) For each sample, an eraser abrasion test was performed, and the abrasion resistance was evaluated using the water contact angle as an indicator. In the eraser abrasion test, a flat surface abrasion tester (DAS-400, manufactured by Daiei Kagaku Seiki Seisakusho) was used, and an eraser for the eraser abrasion test (Minoan, cylindrical type with a contact surface diameter of φ6 mm) was placed on the surface of the anti-reflective film of each sample and moved back and forth. The stroke length of the test stand was set to 50 mm, the reciprocating speed of the test stand to 30 reciprocations / minute, and the applied load to 1.0 kg. The number of reciprocations was set to 2000, 5000, and 10000. After the reciprocation, the water contact angle was measured, and if it was less than 90°, it was evaluated as abrasion progressing (×). On the other hand, if a water contact angle of 90° or more was maintained, it was evaluated as not being a practical problem (△). If a water contact angle of 95° or more was maintained, it was evaluated as light abrasion (〇). Furthermore, if a water contact angle of 100° or more was maintained, it was evaluated as particularly light abrasion (◎). Generally, if surface wear is suppressed to a level rated as "△," "○," or "◎" even after approximately 10,000 back-and-forth cycles, the anti-reflective film can be evaluated as having high abrasion resistance. For all samples, the water contact angle before the abrasion resistance test was 112°.

[0154] (Surface shape profile and three-dimensional surface roughness) Using a three-dimensional optical wave field microscope (MINUK, manufactured by Otsuka Electronics), the surface shape profile of the anti-reflective film was acquired, and various parameters of the three-dimensional surface roughness (arithmetic mean roughness Sa, maximum peak height Sp, skewness Ssk, and crustosis Sku) were measured. The measurement conditions were as follows. Planar resolution: 0.4μm Image area: 704 μm²

[0155] (Density of the convex parts) Three-dimensional shape profile images of each sample surface obtained by the above-mentioned optical wave field three-dimensional microscope observation were imported into graphing software (Wave Metrics' "Igor Pro") to obtain a planar image in which the distribution in the height direction was represented by differences in color. Then, the image was binarized using the planes located at 40 nm and 100 nm in the height direction from the mean plane as thresholds. Figure 6 shows the obtained observation image for the anti-reflective film of Example 2. (a) shows the three-dimensional shape profile image in grayscale, and (b) shows the image binarized with a threshold height of 40 nm on the surface. In Figure 6(b), the areas shown in white represent convex parts with a height of 40 nm or more from the reference plane. The number of areas with a height above the threshold (areas higher than the threshold shown in white in the binarized image) was counted, and 1 mm 2 Converted to the number of items per person

[0156] <Evaluation Results> Table 1 shows the evaluation results for Examples 1-4 and Comparative Examples 1-6, along with the composition of the low refractive index layer (unit of composition: mass %) of the total solid content of the low refractive index layer and the layer composition of the anti-reflective film.

[0157] [Table 1]

[0158] As shown in Table 1, in Examples 1 to 4, the skewness (Ssk) of the three-dimensional surface roughness of the anti-reflective film surface is between 1.00 and 1.14, and the kurtosis (Sku) is between 5.0 and 11.0. Therefore, even with 10,000 cycles of back-and-forth testing, wear is kept to a minimum (○ / ◎ at 10,000 cycles), demonstrating high wear resistance. In particular, Examples 1 and 2, with kurtosis in the range of 7.0 to 8.0, show especially high wear resistance (◎ at 10,000 cycles). Furthermore, in Examples 1 to 4, the haze is kept below 2.0, resulting in high transparency.

[0159] On the other hand, Comparative Examples 1 and 2 exhibit insufficient wear resistance, corresponding to skewness exceeding 1.14 and curtsis exceeding 11.0. Comparative Examples 3 and 4 also exhibit insufficient wear resistance, corresponding to skewness exceeding 1.14. In these comparative examples, the increased skewness and curtsis are thought to be mainly due to the enlargement of the alumina particle size through re-aggregation and self-crosslinking, as seen in the evaluation results of the particle size distribution and protrusion density of the alumina particles. Re-aggregation and self-crosslinking are thought to be progressing due to the fact that the solvent added to the low refractive index layer-forming composition does not have appropriate viscosity and solubility parameters. Furthermore, Comparative Example 2 exhibits a haze exceeding 2.0 and low transparency.

[0160] Comparative Example 5 exhibits insufficient wear resistance, corresponding to a skewness of less than 1.00. The low skewness is thought to be due to a high content of alumina particles in the low refractive index layer. Comparative Example 6 lacks particularly severe wear resistance because it does not contain particles for creating unevenness in the low refractive index layer. The skewness exceeds 1.14 and the kurtosis exceeds 11.0.

[0161] 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]

[0162] 10, 20, 30, 40, 50 Anti-reflective film 12. Base film 14. Hard court layer 15 High refractive index layer 16 Low refractive index layer 18. Anti-fouling layer 22 Transparent adhesive layer 24 Release film 26 Adhesive layer 28 protective films

Claims

1. An anti-reflective film comprising a base film, a hard coat layer formed on the surface of the base film, and a low refractive index layer formed on the surface of the hard coat layer, The low refractive index layer is composed of a cured product of an ionizing radiation-curable composition containing a (meth)acrylate compound having a reactive group, hollow silica particles, and alumina particles surface-treated with a silane coupling agent having a reactive group capable of bonding with the (meth)acrylate compound. An anti-reflective film having a skewness of 1.00 or more and 1.14 or less in the three-dimensional surface roughness of the surface of the anti-reflective film, and a kurtosis of 5.0 or more and 11.0 or less.

2. In the three-dimensional surface roughness profile of the anti-reflective film, the number of protrusions having a height of 40 nm or more from the average surface is 1 mm ２ The number of protrusions is between 100 and 300 per unit area, and the number of protrusions having a height of 100 nm or more from the average surface is 1 mm ２ The anti-reflective film according to claim 1, wherein there are 5 or fewer particles per unit.

3. The anti-reflective film according to claim 1 or claim 2, wherein the content of the alumina particles in the low refractive index layer is 1.0% by mass or more and 8.0% by mass or less, based on 100% by mass of the solid content of the ionizing radiation-curable composition.

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