Antireflective film, and image display device using same

Abstract

Provided are: an antireflective film which has low haze and excellent antiglare properties and in which reductions in antiglare properties when viewed obliquely are suppressed; and an image display device using the antireflective film. The antireflective film is characterized in that formula (A) is satisfied when the maximum value of the relative value of the amount of reflected light with respect to the amount of incident light incident at an incidence angle of 30° is defined as x, the maximum value of the relative value of the amount of reflected light with respect to the amount of incident light incident at an incidence angle of 60° is defined as y, the width of the light receiving angle at which the relative value of the amount of reflected light is 1 / 10 or more of the maximum value x is defined as α, and the width of the light receiving angle at which the relative value of the amount of reflected light is 1 / 10 or more of the maximum value y is defined as β.　Formula (A): β / α ≥ 0.95

Description

Anti-reflection film and image display device using the same

[0001] The present invention relates to an anti-reflection film and an image display device using the same.

[0002] When a display is used in a relatively bright location such as outdoors or under fluorescent lights, reflection of external light such as sunlight or fluorescent lights on the display can be a problem. To prevent this reflection, anti-glare films are used, which have fine irregularities on their surfaces and diffuse the reflected external light.

[0003] Antiglare films include those obtained by coating a transparent film with a transparent resin and then subjecting it to a shaping process using a shaping mold with irregularities, and those obtained by coating a transparent film with a paint in which inorganic or organic transparent fine particles are dispersed in a resin binder (for the latter, see, for example, Patent Documents 1 and 2).

[0004] Japanese Patent No. 4839212 Japanese Patent Application Laid-Open No. 2009-122490

[0005] When anti-glare films are designed to have high anti-glare properties, the haze tends to increase as well, resulting in a decrease in panel contrast and a loss of the luxurious feel due to cloudiness.

[0006] Furthermore, conventional anti-glare films have the problem that, even though they have high anti-glare performance when viewed from the front (in the range of 0 to 30 degrees relative to the normal to the screen), when viewed from an oblique angle (in the range of 45 degrees or more relative to the normal to the screen), the anti-glare performance is significantly reduced compared to when viewed from the front.

[0007] Therefore, an object of the present invention is to provide an anti-reflection film that has low haze and high anti-glare properties and in which the deterioration of the anti-glare properties when viewed from an oblique angle is suppressed, and an image display device using the same.

[0008] The antireflection film according to the present invention is characterized in that it satisfies the following formula (A), where x is the maximum value of the relative value of the amount of reflected light relative to the amount of incident light incident at an incident angle of 30°, y is the maximum value of the relative value of the amount of reflected light relative to the amount of incident light incident at an incident angle of 60°, α is the width of the light-receiving angle at which the relative value of the amount of reflected light is 1 / 10 or more of the maximum value x, and β is the width of the light-receiving angle at which the relative value of the amount of reflected light is 1 / 10 or more of the maximum value y. β / α≧0.95 (A)

[0009] An image display device according to the present invention includes an image display panel and the above-described anti-reflection film.

[0010] The present invention can provide an anti-reflection film that has low haze and high anti-glare properties and in which the deterioration of the anti-glare properties when viewed from an oblique angle is suppressed, and an image display device using the same.

[0011] FIG. 1 is a cross-sectional view schematically illustrating an anti-reflection film according to an embodiment. FIG. 2 is a graph illustrating the relationship between the light-receiving angle and the relative amount of reflected light. It is an SEM image of the anti-glare layer. FIG. 3 is an SEM image of the anti-glare layer. FIG. 4 is a schematic diagram of the anti-glare layer shown in FIG. 3. FIG. 5 is an SEM image of a particle having a plurality of protrusions. FIG. 6 is a schematic diagram of a particle having a plurality of protrusions. FIG. 7 is an SEM image of a porous particle. FIG. 8 is an enlarged image of the surface of the porous particle shown in FIG. 7. FIG. 9 is a graph illustrating the relationship between the light-receiving angle and the relative amount of reflected light for the anti-reflection film according to Example 1-1. FIG. 10 is a graph illustrating the relationship between the light-receiving angle and the relative amount of reflected light for the anti-reflection film according to Comparative Example 1-1. FIG. 11 is a cross-sectional SEM image of an anti-reflection film using porous particles. FIG. 12 is a graph illustrating the relationship between the light-receiving angle and the relative amount of reflected light for the anti-reflection film according to Example 2-1.

[0012] FIG. 1 is a cross-sectional view schematically illustrating an anti-reflection film according to an embodiment.

[0013] The anti-reflection film 1 includes a light-transmitting substrate 2 and an anti-glare layer 3 laminated on one surface of the light-transmitting substrate 2. The anti-glare layer 3 is an optically functional layer that scatters incident light with fine irregularities formed on the surface, thereby suppressing the glare of external light. The anti-reflection film 1 including the anti-glare layer 3 is also called an AG film.

[0014] 2 is a graph showing the relationship between the light-receiving angle and the relative value of the amount of reflected light. The light-receiving angle shown in FIG. 2 represents the angle of reflected light other than specularly reflected light, with the angle of specularly reflected light being taken as the reference angle (0°).

[0015] Let x be the maximum relative value of the reflected light amount relative to the amount of incident light incident at an incident angle of 30°, and let y be the maximum relative value of the reflected light amount relative to the amount of incident light incident at an incident angle of 60°. Here, the relative value of the reflected light amount is the ratio of the amount of reflected light to the amount of incident light, and the maximum values ​​x and y are the maximum values ​​measured while changing the light-receiving angle. Also, let α be the width (1 / 10 value width) of the light-receiving angle at which the relative value of the reflected light amount is 1 / 10 or more of the maximum value x, and let β be the width (1 / 10 value width) of the light-receiving angle at which the relative value of the reflected light amount is 1 / 10 or more of the maximum value y. Figure 2 shows x, y, α, and β.

[0016] The antireflection film of the present invention satisfies the following condition (A): β / α≧0.95 (A)

[0017] The value of β / α is one of the indicators of the antiglare properties when the antireflection film is observed from an oblique direction. When condition (A) is satisfied, the diffusion angle of the reflected light is maintained even when the antireflection film is observed from an oblique direction, and the scattering method is unlikely to change even when the angle of incidence increases, resulting in good antiglare properties when viewed from an oblique direction.

[0018] Furthermore, the antireflection film of the present invention preferably satisfies the following condition (B): y / x≦3.0 (B)

[0019] The value of y / x is one of the indicators of the antiglare properties when the antireflection film is observed from an oblique direction. When condition (B) is satisfied, an increase in the amount of specularly reflected light is suppressed even when the angle of incidence increases, and the antiglare properties when viewed from an oblique direction are good.

[0020] The transmitted image clarity Ic and haze Ha of the antireflection film according to the present invention preferably satisfy the following condition (C). Here, the transmitted image clarity Ic is a value measured using an optical comb with a width of 0.5 mm. The haze (total haze) Ha is a value measured in accordance with JIS K7136. (100-Ic) / Ha≧5 (C)

[0021] The value of (100-Ic) / Ha is an index showing the balance between antiglare properties and haze, and when condition (C) is satisfied, high antiglare properties and low haze can be achieved at the same time. The haze Ha should be 20% or less, and preferably 15% or less.

[0022] The light-transmitting substrate 2 is a film that serves as the base of the anti-reflection film 1, and is made of a material that has excellent transmittance to visible light. Examples of materials that can be used to form the light-transmitting substrate 2 include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyacrylates such as polymethyl methacrylate, polyamides such as nylon 6 and nylon 66, polyimides, polyarylates, polycarbonates, triacetyl cellulose, polyacrylates, polyvinyl alcohol, polyvinyl chloride, cycloolefin copolymers, norbornene-containing resins, polyethersulfones, and polysulfones, as well as transparent resins and inorganic glass. The thickness of the light-transmitting substrate 2 is not particularly limited, but is preferably 10 to 200 μm.

[0023] The surface of the light-transmitting substrate 2 may be subjected to a surface modification treatment in order to improve adhesion with other layers to be laminated thereon. Examples of surface modification treatments include alkali treatment, corona treatment, plasma treatment, sputtering treatment, application of a surfactant or a silane coupling agent, and Si vapor deposition.

[0024] The antiglare layer 3 is a functional layer that forms a fine uneven shape on the outermost surface of the antireflection film 1. The antiglare layer 3 is formed by applying a coating liquid containing an ultraviolet-curable compound, fine particles (filler), and a photopolymerization initiator to the light-transmitting substrate 2 and curing the coating film.

[0025] As the ultraviolet-curable compound, for example, a monofunctional, difunctional, trifunctional or higher functional (meth)acrylate monomer can be used. In this specification, "(meth)acrylate" is a general term for both acrylate and methacrylate, and "(meth)acryloyl" is a general term for both acryloyl and methacryloyl.

[0026] Examples of monofunctional (meth)acrylate compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, glycidyl (meth)acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isobornyl (meth)acrylate. acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, benzyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, ethyl carbitol (meth)acrylate, phosphate (meth)acrylate, ethylene oxide-modified phosphate (meth)acrylate, phenoxy (meth)acrylate, ethylene oxide-modified phenoxy (meth)acrylate, propylene oxide ethylene oxide-modified phenoxy (meth)acrylate, nonylphenol (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, propylene oxide-modified nonylphenol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxypolyethylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, ) acryloyloxyethyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hydrogen phthalate, 2-(meth)acryloyloxypropyl hexahydrohydrogen phthalate, 2-(meth)acryloyloxypropyl tetrahydrohydrogen phthalate, dimethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropropyl (meth)acrylate, 2-adamantane,adamantane derivative mono(meth)acrylates such as adamantyl acrylate having a monovalent mono(meth)acrylate derived from adamantanediol, etc.

[0027] Examples of bifunctional (meth)acrylates include di(meth)acrylates such as ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, nonanediol di(meth)acrylate, ethoxylated hexanediol di(meth)acrylate, propoxylated hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethoxylated neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and hydroxypivalic acid neopentyl glycol di(meth)acrylate.

[0028] Examples of tri- or higher functional (meth)acrylates include tri(meth)acrylates such as trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, tris-2-hydroxyethyl isocyanurate tri(meth)acrylate, and glycerin tri(meth)acrylate; trifunctional (meth)acrylate compounds such as pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, and ditrimethylolpropane tri(meth)acrylate;

[0033] Examples of the polyfunctional (meth)acrylate include tri- or higher functional (meth)acrylate compounds such as pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and ditrimethylolpropane hexa(meth)acrylate, as well as polyfunctional (meth)acrylate compounds in which a portion of these (meth)acrylates is substituted with an alkyl group or ε-caprolactone.

[0029] Urethane (meth)acrylates can also be used as polyfunctional monomers. Examples of urethane (meth)acrylates include those obtained by reacting a polyester polyol with an isocyanate monomer or a prepolymer, and then reacting the resulting product with a (meth)acrylate monomer having a hydroxyl group.

[0030] Examples of urethane (meth)acrylates include pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, and dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer.

[0031] The polyfunctional monomers may be used alone or in combination of two or more. In addition, the polyfunctional monomers may be in the form of a monomer in the coating liquid, or may be in the form of a partially polymerized oligomer.

[0032] The fine particles (filler) form minute irregularities on the surface of the antiglare layer 3, thereby imparting a function of diffusing external light. As the fine particles, spherical fine particles may be used, or irregularly shaped fine particles such as fine particles having multiple protrusions or porous fine particles may be used. Furthermore, two or more types of fine particles with different particle diameters (core particle diameters in the case of irregularly shaped fine particles) may be used.

[0033] FIG. 3 is an SEM image of the antiglare layer, and FIG. 4 is a schematic diagram of the antiglare layer shown in FIG.

[0034] 3 and 4 have a generally spherical shape. Examples of materials that can be used for the particles include acrylic resins, polystyrene resins, acrylic-styrene copolymers, polyethylene resins, epoxy resins, silicone resins, polyvinylidene fluoride, and polyethylene fluoride resins. When two types of particles that satisfy the following conditions (1) to (3) are used as the filler in the antiglare layer 3, the light incident on the antiglare layer 3 is multiple-scattered, thereby improving the antiglare properties of the antireflection film when viewed obliquely.

[0035] Here, the radii of the two types of microparticles are defined as r1 and r2 (see FIG. 4, where r1>r2). The radii r1 and r2 are approximate values ​​measured assuming that the microparticles are spherical. The radii r1 and r2 are values ​​measured from an SEM image of the cross section of the anti-reflection film, and are taken as the average radii of circles that overlap the peripheries of 100 porous microparticles in the SEM image. The radii r1 and r2 of the two types of microparticles used in the anti-reflection film according to this embodiment satisfy the following formulas (1), (2), and (3): 0.75 μm≦r1≦4.0 μm ... (1) 0.10 μm≦r2≦1.0 μm ... (2) 0.25 μm≦r1-r2 ... (3)

[0036] When the radius r1 of the relatively large particles is less than 0.75 μm, the haze is small, but the antiglare properties are also reduced. When the radius r1 exceeds 4.0 μm, the antiglare properties are increased, but the haze is also increased. When the radius r1 of the relatively large particles is within the range of formula (1), high antiglare properties and low haze can both be achieved. Note that the haze of the antireflection film of the present invention is sufficient if it is 17% or less, and more preferably 15% or less.

[0037] When the radius r2 of the relatively small particles is less than 0.10 μm or exceeds 1.0 μm, the antiglare properties of the antireflection film when viewed obliquely are reduced. In other words, if the radius r2 of the relatively small particles is too large or too small, the light diffusion is weakened and the multiple scattering effect is not fully achieved.

[0038] FIG. 5 is an SEM image of a particle having a plurality of protrusions, and FIG. 6 is a schematic diagram of a particle having a plurality of protrusions.

[0039] The microparticle shown in Fig. 5 has a spherical core and multiple protrusions protruding from the surface of the core. The protrusions on the surface of the microparticle have a shape that approximates a portion of a sphere, and the outer surface of the protrusions is approximately spherical. Examples of materials that can be used for the microparticles having multiple protrusions include acrylic resin and polymethylsilsesquioxane (PMSQ), and they may contain particles such as alumina, titanium oxide, and silica.

[0040] Here, the radius of the nucleus is r3, and the radius of the protrusion is r4 (see FIG. 6). The radii r3 and r4 are approximate values ​​measured assuming the nucleus and protrusions are spheres, and specifically, they are values ​​calculated as the radius of a circle passing through any three points on the outline of the nucleus and protrusions shown in the SEM image. As an example, in FIG. 6, a circle passing through any three points on the outline of one of the protrusions is shown by a dashed line.

[0041] The radius r3 of the core is preferably 0.75 to 4.0 μm, and the radius r4 of the protrusion is preferably 0.05 to 1.0 μm. The difference between the radii r3 and r4 (where r3 > r4) is preferably 0.25 μm or more. When the radii r3 and r4 are within these ranges, reflected light is easily scattered over a wide range, which is advantageous for improving the antiglare properties when the antireflection film is viewed obliquely.

[0042] Fig. 7 is an SEM image of the porous microparticle, and Fig. 8 is an enlarged image of the surface of the porous microparticle shown in Fig. 7. The dark areas shown in Fig. 7 correspond to the pores formed on the surface of the porous microparticle.

[0043] The porous microparticles are a material that forms minute irregularities on the surface of the antiglare layer 3 and imparts the function of diffusing external light. As shown in Figure 7, the porous microparticles are particles that have an approximately spherical shape overall and have a large number of pores on the surface. Examples of materials that can be used for the porous microparticles include acrylic resins. When porous microparticles that satisfy the following conditions (4) and (5) are used as the filler for the antiglare layer 3, the antiglare properties of the antireflection film can be improved when viewed obliquely due to multiple scattering of light incident on the surfaces of the porous microparticles.

[0044] Here, the radius of the core is r5, and the radius of the pores of the porous microparticles is r6 (see Figures 7 and 8). The radii r5 and r6 are approximate values ​​measured assuming that the core and pores are spherical. The radius r5 is a value measured from an SEM image of the cross section of the anti-reflection film, and is the average value of the radii of circles overlapping the peripheries of 100 porous microparticles in the SEM image. The gas desorption isotherm is measured in accordance with JIS Z8831-2, and r6 is the average radius calculated from the pore size distribution obtained from the obtained desorption isotherm using the BJH method. The radii r1 and r6 of the porous microparticles used in the anti-reflection film according to this embodiment satisfy the following formulas (4) and (5). 0.75 μm≦r5≦4.0 μm (4) 0.002 μm≦r6≦0.010 μm (5)

[0045] FIG. 11(a) is a cross-sectional SEM image of an anti-reflection film using porous microparticles, and FIG. 11(b) is an enlarged view of the porous microparticle portion.

[0046] In addition to the above-mentioned method, the pore radius r6 can also be measured by taking an SEM image of the cross section of the anti-reflection film, regarding the black areas (depressions) inside the particles in the SEM image as pores, measuring the radii of the circles that most closely resemble the black areas at 100 locations, and calculating the average value of the 100 locations.

[0047] When the core radius r5 is less than 0.75 μm, the haze is small, but the antiglare properties are also reduced. When the core radius r5 exceeds 4.0 μm, the antiglare properties are increased, but the haze is also increased. When the core radius r5 is within the range of formula (4), high antiglare properties and low haze can both be achieved. Note that the haze of the antireflection film according to the present invention may be 17% or less, and more preferably 15% or less.

[0048] If the pore radius r6 is less than 0.002 μm, the shape of the porous microparticles becomes nearly spherical, resulting in a decrease in the anti-glare properties when the anti-reflection film is viewed obliquely.If the pore radius r6 exceeds 0.010 μm, it becomes difficult to obtain the multiple scattering effect, resulting in a decrease in the anti-glare properties when the anti-reflection film is viewed obliquely.

[0049] As the photopolymerization initiator, radical polymerization initiators such as acetophenone-based, benzophenone-based, thioxanthone-based, benzoin, benzoin methyl ether, and acylphosphine oxide can be used. Examples of the photopolymerization initiator include diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-phenylacetophenone, dibenzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, p-chlorobenzophenone, p-methoxybenzophenone, Michler's ketone, acetophenone, and 2-chlorothioxanthone. One of these may be used alone, or two or more may be used in combination.

[0050] If necessary, inorganic fine particles (inorganic nanoparticles) having an average particle size of 10 to 200 nm may be added to the composition for forming the antiglare layer.

[0051] The inorganic fine particles function as a thickener that increases the viscosity of the antiglare layer-forming composition and are a material for adjusting the sedimentation and aggregation of fine particles in the antiglare layer 3. Examples of inorganic fine particles that can be used include silica fine particles, metal oxide fine particles, and various mineral fine particles. Examples of silica fine particles include colloidal silica and silica fine particles surface-modified with reactive functional groups such as (meth)acryloyl groups. Examples of metal oxide fine particles that can be used include alumina, zinc oxide, tin oxide, antimony oxide, indium oxide, titania, and zirconia. Examples of mineral fine particles that can be used include mica, synthetic mica, vermiculite, montmorillonite, iron-montmorillonite, bentonite, beidellite, saponite, hectorite, stevensite, nontronite, magadiite, ilealite, kanemite, layered titanic acid, smectite, and synthetic smectite. The mineral fine particles may be natural or synthetic (including substituted or derivative) materials, or a mixture of both. Among the mineral fine particles, layered organic clay is more preferred. Layered organic clay refers to a swelling clay in which organic onium ions are introduced between the layers. The organic onium ions are not limited as long as they can be organized by utilizing the cation exchange property of the swelling clay. When a layered organic clay mineral is used as the mineral fine particles, the above-mentioned synthetic smectite can be preferably used.

[0052] The antiglare layer-forming composition may also contain components for improving antifouling properties, such as an antifouling agent, a leveling agent, an oil repellent, a water repellent, or an antifingerprint agent. Fluorine-containing compounds and silicone compounds can be suitably used as these additives. Other additives, such as antistatic agents, antifoaming agents, antioxidants, ultraviolet absorbers, infrared absorbers, colorants, light stabilizers, polymerization inhibitors, and photosensitizers, may also be added as needed.

[0053] The antiglare layer-forming composition may contain a solvent, if necessary. Examples of the solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, butanol, isopropyl alcohol, and isobutanol; ketones such as acetone, methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; ketone alcohols such as diacetone alcohol; aromatic hydrocarbons such as benzene, toluene, and xylene; glycols such as ethylene glycol, propylene glycol, and hexylene glycol; glycol ethers such as ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, diethyl cellosolve, diethyl carbitol, and propylene glycol monomethyl ether; esters such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, and amyl acetate; ethers such as dimethyl ether and diethyl ether; and N-methylpyrrolidone and dimethylformamide, which may be used alone or in combination.

[0054] Between the light-transmitting substrate 2 and the antiglare layer 3, one or more other functional layers such as a hard coat layer, a high refractive index layer, a medium refractive index layer, an antistatic layer, an electromagnetic wave blocking layer, an infrared absorbing layer, an ultraviolet absorbing layer, or a color correction layer may be laminated as necessary.

[0055] The method for applying the antiglare layer-forming composition and the low refractive index layer-forming composition is not particularly limited, and for example, they can be applied using a spin coater, a roll coater, a reverse roll coater, a gravure coater, a microgravure coater, a knife coater, a bar coater, a wire bar coater, a die coater, a dip coater, a spray coater, an applicator, or the like.

[0056] As described above, the antireflection film according to this embodiment satisfies the above-mentioned condition (A) in the 1 / 10 value width α of the relative value of the reflected light amount relative to the light amount of incident light incident at an incident angle of 30° and the 1 / 10 value width β of the relative value of the reflected light amount relative to the light amount of incident light incident at an incident angle of 60°. In other words, the reflected light of light incident at an incident angle of 60° is diffused widely over an angular range comparable to or greater than that of the reflected light of light incident at an incident angle of 30°. Therefore, the antireflection film according to this embodiment is less likely to change in scattering mode even with increasing incident angles, and exhibits excellent antiglare properties when viewed obliquely. According to this embodiment, the reflected light can be diffused over a wide range, thereby achieving high antiglare properties (low image clarity) while maintaining low haze. The antireflection film according to this embodiment can achieve both low haze and high antiglare properties. Therefore, when used in an image display device, it is possible to suppress the effects of external light glare while also suppressing a decrease in image contrast.

[0057] Anti-glare films that have been subjected to anti-glare treatment by shaping treatment or anti-glare films that contain spherical fillers in the anti-glare layer have a problem in that even though they have high anti-glare performance when viewed from the front (in the range of 0 to 30 degrees relative to the normal to the screen), their anti-glare performance tends to decrease when viewed from an oblique angle (in the range of 45 degrees or more relative to the normal to the screen) compared to when viewed from the front.

[0058] When two types of fine particles with different particle sizes are used as fillers in the anti-glare layer of an anti-reflection film, dense unevenness is formed, making it easy for incident light to be multiple-scattered. Although the scattering angle is small, the incident light can be scattered in complex directions in many directions, making it possible to achieve high anti-glare properties (low image clarity) while maintaining low haze. Furthermore, the multiple scattering of incident light by two types of fine particles with different particle sizes makes it possible to efficiently scatter incident light even when the light is incident from an oblique direction. Since the anti-reflection film according to this embodiment can achieve both low haze and high anti-glare properties, when used in an image display device, it is possible to suppress the effects of external light reflections and also suppress a decrease in image contrast.

[0059] When porous microparticles are used as a filler in the antiglare layer of an antireflection film, the pores of the porous microparticles tend to multiple-scatter incident light. Although the scattering angle is small, the incident light can be scattered in complex directions in many directions, making it possible to achieve high antiglare properties (low image clarity) while maintaining low haze. Furthermore, the multiple scattering of incident light by the porous microparticles allows the incident light to be efficiently scattered even when the light is incident from an oblique direction. Since the antireflection film according to this embodiment can achieve both low haze and high antiglare properties, when used in an image display device, it is possible to suppress the effects of external light glare while also suppressing a decrease in image contrast.

[0060] The anti-reflection film according to this embodiment can be used to construct an image display device by being attached to the outermost surface of an image display panel such as a liquid crystal panel or an organic EL panel. A touch panel may be provided between the anti-reflection film and the image display panel. The anti-reflection film according to this embodiment has excellent anti-glare properties when viewed from an oblique angle, and therefore has high anti-glare properties, can display vivid images, and is suitable for large displays intended to be viewed from multiple directions, such as public information displays (PIDs).

[0061] Examples of specific implementations of the present invention will be described below.

[0062] Examples 1-1 to 1-5: A 40 μm-thick triacetyl cellulose (TAC) film was used as the light-transmitting substrate. A composition for forming an antiglare layer was prepared by diluting with a solvent a concentration suitable for coating, containing pentaerythritol triacrylate (a UV-curable compound), two types of fine particles (organic filler) with different particle sizes, Omnirad® 184 (a photopolymerization initiator), organically treated synthetic clay (a thickener), a leveling agent, and colloidal silica (an additive) in the proportions shown in Tables 1 and 2 below. The composition is in mass %. The composition for forming an antiglare layer was applied to a light-transmitting substrate so that the film thickness after curing was approximately equal to the particle size of the larger fine particles and so that the fine particles were embedded in the antiglare layer. After drying, the coating film was polymerized and cured by UV irradiation to form an antiglare layer, and antireflection films according to each Example and Comparative Example were obtained.

[0063]

[0064]

[0065] The radii r1 and r2 of the fine particles used in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5 were measured as follows. An SEM image of the cross section of the antireflection film was obtained, and the outer shapes of the fine particles included in the SEM image were considered to be spheres. The radii of the circles that most closely resembled the outer shapes of the fine particles were measured at 100 locations. The average value of the radii of 100 relatively large fine particles was taken as r1, and the average value of the radii of 100 relatively small fine particles was taken as r2.

[0066] (Haze Ha) Haze was measured in accordance with JIS K 7105 using a haze meter (NDH 4000, manufactured by Nippon Denshoku Industries Co., Ltd.).

[0067] (Transmitted Image Clarity Ic) The transmitted image clarity was measured in accordance with JIS K 7105 using an image clarity measuring instrument (ICM-1T, manufactured by Suga Test Instruments Co., Ltd.) in transmission mode with an optical comb width of 0.5 mm.

[0068] (Relative Value of Reflected Light Amount) The relative value of reflected light amount was measured using a goniophotometer (goniophotometer, GP-5, manufactured by Murakami Color Research Laboratory Co., Ltd.). A black acrylic plate was attached to the uncoated surface of an antireflection film using an optical adhesive, and used as a measurement sample. In addition, as a reference, a black acrylic plate was attached to one side of a light-transmitting substrate (the same side as the uncoated surface of the antireflection film) using an optical adhesive, and the same side as the coated surface of the antireflection film was used as the measurement surface.

[0069] The measurement conditions for the goniophotometer were set as follows: <Measurement conditions> - Measurement mode: Reflection - Measurement item: Variable angle - VS1 (aperture on the light source (light beam) side): 2.0 - VS2 (aperture on the light receiving side): 3.0 - IA (angle of incident light): 30° or 60° - FA (tilt angle): 0.0° - Receiving angle range (RA): specular reflection angle ±20° (when the incident angle is 30°, R1: 10°, R2: 50°; when the incident angle is 60°, R1: 40°, R2: 80°) - Sensitivity check: performed (start: R1, end: R2) - Neutral density filter: not used - ND filter: not used - Data acquisition interval: 0.1°

[0070] The relative value of the reflected light amount was determined by the following method. First, using the measurement surface of the reference, the reflected light amount was measured at intervals of 0.1° within the above-mentioned light-receiving angle range, and the relative value of the reflected light amount (maximum value) at the light-receiving angle at which the actual measured value of the reflected light amount was maximum was defined as 100. Next, a coefficient was calculated by dividing the maximum value of the relative value of the reflected light amount (=100) of the reference by the actual measured value of the reflected light amount (maximum value). Next, using the coated surface of the antireflection film according to each example and each comparative example, the reflected light amount was measured at intervals of 0.1° within the above-mentioned light-receiving angle range, and the product of the actual measured value of the reflected light amount and the coefficient determined from the reference was defined as the relative value of the reflected light amount.

[0071] The relative value of the reflected light amount was calculated for each of the incident angles of 30° and 60°, and the maximum value of the relative value of the reflected light amount at an incident light angle of 30° was designated x, and the maximum value of the relative value of the reflected light amount at an incident light angle of 60° was designated y. In addition, on a plane with the horizontal axis representing the light-receiving angle and the vertical axis representing the relative value of the reflected light amount, the light-receiving angle range (absolute value) at which x and y were 1 / 10 or more was determined from a graph of the light-receiving angle and the calculated relative value of the reflected light amount.

[0072] (Anti-glare property evaluation) Samples were prepared by laminating a black acrylic plate to the uncoated surface of the anti-reflection film according to each example and comparative example using an optical pressure-sensitive adhesive. The anti-glare property when the anti-reflection film was observed from the front, with fluorescent light irradiated from the front of the anti-reflection film and a position 40 cm away from the anti-reflection film surface, was defined as "front anti-glare property." The anti-glare property when the anti-reflection film was observed from the specular reflection direction (a direction horizontal to the normal to the anti-reflection film and tilted 60 degrees toward the opposite side of the light source) with fluorescent light irradiated from a position 40 cm away from the anti-reflection film surface, was defined as "60-degree anti-glare property."

[0073] Twenty evaluators visually compared the front anti-glare properties and 60-degree anti-glare properties of the anti-reflection films and assigned scores according to the following criteria: <Evaluation criteria> 4 points: 60-degree anti-glare properties are equivalent to the front anti-glare properties 3 points: 60-degree anti-glare properties are slightly inferior to the front anti-glare properties 2 points: 60-degree anti-glare properties are significantly inferior to the front anti-glare properties 1 point: Almost no 60-degree anti-glare properties

[0074] The average scores of 20 panelists were classified according to the following criteria to obtain an evaluation value. If the score is level 5 or higher on the following criteria, the oblique antiglare properties are good. <Evaluation Values> Level 6: More than 3.5 and 4.0 or less Level 5: More than 3.0 and 3.5 or less Level 4: More than 2.5 and 3.0 or less Level 3: More than 2.0 and 2.5 or less Level 2: More than 1.5 and 2.0 or less Level 1: 1.0 or more and 1.5 or less

[0075] Table 3 also shows the particle size of the fine particles used in the antireflection films of each Example and Comparative Example, as well as the evaluation values ​​of the transmitted image clarity, haze, relative value of the reflected light amount, and diagonal antiglare property.

[0076]

[0077] The anti-reflection films according to Examples 1-1 to 1-5 had two types of fine particles that satisfied the above conditions (1) to (3) added to the anti-glare layer, and therefore had good front anti-glare properties and good 60-degree anti-glare properties while suppressing haze.

[0078] The anti-reflection films of Comparative Examples 1-1 and 1-2 have fine particles of a single particle size added to the anti-glare layer. The anti-reflection films of Comparative Examples 1 and 2 both had significantly reduced 60-degree anti-glare properties. Furthermore, because the amount of fine particles added was greater than in Examples 1 to 5, the haze increased, and the indices of low haze and high anti-glare properties, (100-Ic) / Ha and β / α, were deteriorated.

[0079] In the antireflection films according to Comparative Examples 1-3 and 1-4, the radius r1 of the relatively large fine particles exceeded the upper limit of the above-mentioned condition (1), and therefore the haze increased, and the indices of low haze and high antiglare properties, (100-Ic) / Ha and β / α, were deteriorated.

[0080] In the antireflection film according to Comparative Example 1-5, the radius r2 of the relatively small fine particles exceeded the upper limit of the above condition (2), and therefore the 60-degree antiglare property was deteriorated compared to the Examples.

[0081] 9 and 10 are graphs showing the relationship between the light-receiving angle and the relative value of the amount of reflected light for the antireflection films according to Example 1-1 and Comparative Example 1-1, respectively.

[0082] In the antireflection film of Comparative Example 1-1 (using spherical microparticles of one particle size) shown in Figure 9, when the angle of incidence of incident light is 60°, the proportion of reflected light components close to specularly reflected light is higher than when the angle of incidence is 30°. In contrast, in the antireflection film of Example 1-1 (using two types of microparticles with different particle sizes) shown in Figure 10, the amount of specularly reflected light is suppressed more than in Comparative Example 1-1, and the reflected light is dispersed over a wider range of light-receiving angles than in Comparative Example 1. It was confirmed that the antireflection film of Example 1-1 can suppress specularly reflected light and exhibit high antiglare properties even when the angle of incidence is large, as the two types of microparticles with different particle sizes multiple-scatter the incident light.

[0083] Examples 2-1 to 2-4: A 40 μm-thick triacetyl cellulose (TAC) film was used as the light-transmitting substrate. A composition for forming an antiglare layer was prepared by diluting with a solvent a concentration suitable for coating and containing pentaerythritol triacrylate (UV-curable compound), organic filler (porous microparticles), Omnirad (registered trademark) 184 (photopolymerization initiator), organically treated synthetic clay (thickener), leveling agent, and colloidal silica (additive) in the proportions shown in Tables 1 and 2 below. The composition is in mass %. The composition for forming an antiglare layer was applied to a light-transmitting substrate so that the film thickness after curing was approximately equal to the diameter of the cores of the porous microparticles and so that the cores were embedded in the antiglare layer. After drying, the coating was polymerized and cured by UV irradiation to form an antiglare layer, and antireflection films according to each Example and Comparative Example were obtained.

[0084]

[0085]

[0086] The radius r5 of the core of the fine particles used in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-5 was measured as follows: An SEM image of the cross section of the antireflection film was obtained, the outer shape of the fine particles in the SEM image was considered to be a sphere, and the radius of the circle that most closely resembled the outer shape of the fine particles was measured at 100 locations, and the average value was taken as r5.

[0087] The pore radius r6 of the porous microparticles used in Examples 1 to 4 and Comparative Examples 3 to 5 was measured in accordance with JIS Z8831-2 as follows. First, a container containing the porous microparticles was heated at 65°C while being purged with nitrogen for 20 minutes. After allowing the container to cool to room temperature, the container containing the porous microparticles was heated at 65°C and vacuum degassed until the pressure inside the container reached 0.05 mmHg or less. Next, the nitrogen desorption isotherm of the porous microparticles was measured using an automatic specific surface area / pore distribution analyzer (Tristar 3030, manufactured by Shimadzu Corporation). The nitrogen desorption isotherm was measured using nitrogen as the adsorbate, and the adsorbate cross-sectional area was 0.162 nm ２ The nitrogen desorption isotherm was analyzed by the BJH method using software attached to the automatic specific surface area / pore distribution analyzer, and the calculated average radius of the pores was taken as r6.

[0088] The haze Ha, transmitted image clarity Ic, maximum value x of the relative value of the amount of reflected light at an incident light angle of 30°, maximum value y of the relative value of the amount of reflected light at an incident light angle of 60°, widths α and β (absolute values) of the light-receiving angles at which x and y are 1 / 10 or more, and evaluation values ​​of the antiglare properties of the antireflection films according to each example and comparative example were obtained in the same manner as in Examples 1-1 to 1-5.

[0089] Table 4 also shows the shape and size of the organic filler used in the anti-reflection films of each Example and Comparative Example, as well as the evaluation values ​​of transmitted image clarity, haze, relative reflected light amount, and oblique anti-glare property.

[0090]

[0091] The anti-reflection films according to Examples 2-1 to 2-4 had porous microparticles in the anti-glare layer that satisfied the above conditions (4) and (5), and therefore had good front anti-glare properties and good 60-degree anti-glare properties while suppressing haze.

[0092] The anti-reflection films of Comparative Examples 2-1 and 2-2 had good front anti-glare properties, but because the microparticles used were spherical, the 60-degree anti-glare properties were significantly reduced. Furthermore, the 60-degree anti-glare properties were worsened because the amount of microparticles added was greater than in Examples 2-1 to 2-4. Furthermore, the haze increased, and the (100-Ic) / Ha ratio, which is an index of low haze and high anti-glare properties, also deteriorated. In Comparative Example 2-1, the value of y / x also deteriorated.

[0093] Although the anti-reflection films according to Comparative Examples 2-3 and 2-4 contain porous microparticles in the anti-glare layer, they do not satisfy the above-mentioned condition (4), and therefore the haze is high and the (100-Ic) / Ha ratio, which is an index of low haze and high anti-glare properties, is also deteriorated.

[0094] The anti-reflection film of Comparative Example 2-5, although containing porous particles in the anti-glare layer, did not satisfy the above condition (5), and therefore the 60° anti-glare property was deteriorated. In addition, the (100-Ic) / Ha ratio, which is an index of low haze and high anti-glare property, was also deteriorated.

[0095] 12 is a graph showing the relationship between the light-receiving angle and the relative value of the reflected light amount for the antireflection film of Example 2-1. Note that Comparative Example 2-1, which uses spherical fine particles as the filler, is the same as Comparative Example 1-1 described above, and therefore the graph of Example 2-1 shown in FIG. 12 will be compared with the graph of Comparative Example 1-1 shown in FIG. 10 below.

[0096] In the antireflection film of Comparative Example 1-1 (using spherical microparticles) shown in Figure 10, when the incident angle of incident light is 60°, the proportion of reflected light components close to specularly reflected light is higher than when the incident angle is 30°. In contrast, in the antireflection film of Example 2-1 (using porous microparticles) shown in Figure 12, the amount of specularly reflected light is suppressed more than in Comparative Example 1, and the reflected light is dispersed over a wider range of light receiving angles than in Comparative Example 1-1 (Comparative Example 2-1). It was confirmed that the antireflection film of Example 2-1 can suppress specularly reflected light and exhibit high antiglare properties even when the incident angle is large, by multiple scattering of incident light by the porous microparticles.

[0097] The present invention can be used as an anti-reflection film for image display devices and the like.

[0098] 1 Anti-reflection film 2 Transparent substrate 3 Anti-glare layer

Claims

1. An antireflection film characterized by satisfying the following formula (A): β / α≧0.95 (A), where x is the maximum relative value of the amount of reflected light relative to the amount of incident light incident at an incident angle of 30°, y is the maximum relative value of the amount of reflected light relative to the amount of incident light incident at an incident angle of 60°, α is the width of the light-receiving angle at which the relative value of the amount of reflected light is 1 / 10 or more of the maximum value x, and β is the width of the light-receiving angle at which the relative value of the amount of reflected light is 1 / 10 or more of the maximum value y.

2. The anti-reflection film according to claim 1, wherein the maximum value of the relative amount of reflected light to the amount of incident light incident at an incident angle of 30° is defined as x, and the maximum value of the relative amount of reflected light to the amount of incident light incident at an incident angle of 60° is defined as y, satisfying the following formula (B): y / x≦3.0 (B) 3. The anti-reflection film according to claim 1, wherein the transmitted image clarity Ic at a 0.5 mm comb width and the haze Ha satisfy the following formula (C): (100-Ic) / Ha≧5 (C) 4. The anti-reflection film according to claim 1, comprising a light-transmitting substrate and one or more optical functional layers laminated on the light-transmitting substrate, wherein an uneven shape is formed on at least one surface of the optical functional layer, wherein the optical functional layer contains two types of fine particles having different particle sizes, and wherein the radii r1 and r2 of the two types of fine particles satisfy the following formulas (1), (2), and (3): 0.75 μm≦r1≦4.0 μm ... (1) 0.10 μm≦r2≦1.0 μm ... (2) 0.25 μm≦r1-r2 ... (3) 5. The anti-reflection film according to claim 1, comprising a light-transmitting substrate and one or more optical functional layers laminated on the light-transmitting substrate, wherein an uneven shape is formed on at least one surface of the optical functional layer, and wherein the optical functional layer contains porous microparticles, and wherein the radius r5 of the core of the porous microparticles and the radius r6 of the pores on the surface of the porous microparticles satisfy the following formulas (4) and (5): 0.75 μm≦r5≦4.0 μm (4) 0.002 μm≦r6≦0.010 μm (5) 6. An image display device comprising: an image display panel; and the anti-reflection film according to claim 1.

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