Antireflection film and image display device using the same

Abstract

The present application provides a low-haze and high-anti-glare antireflection film, which suppresses the decrease in anti-glare property when viewed from an oblique direction, and an image display device using the same. An antireflection film, characterized in that, when the maximum value of the relative value of the reflected light amount with respect to the light amount of incident light incident at an incident angle of 30° is set as x, the maximum value of the relative value of the reflected light amount with respect to the light amount of incident light incident at an incident angle of 60° is set as y, the width of the light receiving angle of which the relative value of the reflected light amount is 1 / 10 or more of the maximum value x is set as α, and the width of the light receiving angle of which the relative value of the reflected light amount is 1 / 10 or more of the maximum value y is set as β, the following formula (A) is satisfied: β / α ≥ 0.95 (A).

Description

Technical Field

[0001] This invention relates to an anti-reflective film and an image display device using the anti-reflective film. Background Technology

[0002] When using a monitor in bright environments such as outdoors or under fluorescent lights, the reflection of external light such as sunlight or fluorescent lamps onto the monitor becomes a problem. To prevent external light from entering, an anti-glare film is used, which has a surface with micro-textures that diffuse and reflect the reflected external light.

[0003] As an anti-glare film, there are films made by coating a transparent film with a transparent resin and then shaping it using a molding die with concave and convex surfaces; or films made by coating a transparent film with a coating containing inorganic or organic transparent microparticles dispersed in a resin binder (for the latter, see, for example, Patent Documents 1 and 2).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 4839212

[0007] Patent Document 2: Japanese Patent Application Publication No. 2009-122490 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] When an anti-glare film is designed to have high anti-glare performance, the haze can easily increase, leading to a decrease in panel contrast or a reduction in the sense of sophistication due to cloudiness.

[0010] In addition, previous anti-glare films had the following problems: the anti-glare performance was high when viewed from the front (within the range of 0 to 30° relative to the normal of the screen), but when viewed from an angle (within the range of 45° or more relative to the normal of the screen), the anti-glare performance was significantly reduced compared to when viewed from the front.

[0011] Therefore, the object of the present invention is to provide an anti-reflective film with low haze and high anti-glare performance, which suppresses the reduction of anti-glare performance when viewed from an oblique angle, and an image display device using the anti-reflective film.

[0012] Methods for solving problems

[0013] The antireflective film of the present invention is characterized in that, when the maximum value of the relative value of the reflected light amount with respect to the light amount of incident light incident at an incident angle of 30° is set as x, the maximum value of the relative value of the reflected light amount with respect to the light amount of incident light incident at an incident angle of 60° is set as y, the width of the light-receiving angle with a relative value of the reflected light amount of more than 1 / 10 of the maximum value x is set as α, and the width of the light-receiving angle with a relative value of the reflected light amount of more than 1 / 10 of the maximum value y is set as β, the following formula (A) is satisfied.

[0014] β / α ≥ 0.95 (A)

[0015] The image display device of the present invention includes an image display panel and the aforementioned anti-reflective film.

[0016] The effects of the invention

[0017] The present invention can provide an anti-reflective film with low haze and high anti-glare performance, which suppresses the reduction of anti-glare performance when viewed from an oblique angle, and an image display device using the anti-reflective film. Attached Figure Description

[0018] [ Figure 1 ] Figure 1 This is a schematic cross-sectional view of the antireflective film according to the embodiment.

[0019] [ Figure 2 ] Figure 2 This is a curve showing the relationship between the angle of light received and the relative value of reflected light, and an SEM image of the anti-glare layer.

[0020] [ Figure 3 ] Figure 3 This is an SEM image of the anti-glare layer.

[0021] [ Figure 4 ] Figure 4 yes Figure 3 A schematic diagram of the anti-glare layer is shown.

[0022] [ Figure 5 ] Figure 5 It is an SEM image of particles with multiple protrusions.

[0023] [ Figure 6 ] Figure 6 It is a schematic diagram of a particle with multiple protrusions.

[0024] [ Figure 7 ] Figure 7 It is a SEM image of porous microparticles.

[0025] [ Figure 8 ] Figure 8 yes Figure 7 A magnified image of the porous microparticle surface shown.

[0026] [ Figure 9 ] Figure 9 It is a graph showing the relationship between the light-receiving angle and the relative value of the reflected light amount of the anti-reflective film involved in Example 1-1.

[0027] [ Figure 10 ] Figure 10 This is a graph showing the relationship between the light-receiving angle and the relative value of the reflected light amount of the antireflective film involved in Comparative Example 1-1.

[0028] [ Figure 11 ] Figure 11 This is a cross-sectional SEM image of an antireflective film using porous microparticles.

[0029] [ Figure 12 ] Figure 12 It is a graph showing the relationship between the light-receiving angle and the relative value of the reflected light amount of the anti-reflective film involved in Example 2-1. Detailed Implementation

[0030] Figure 1 This is a schematic cross-sectional view of the antireflective film according to the embodiment.

[0031] The anti-reflective film 1 comprises a light-transmitting substrate 2 and an anti-glare layer 3 laminated on one side of the light-transmitting substrate 2. The anti-glare layer 3 is an optical functional layer that suppresses the reflection of external light by scattering incident light through the micro-unfolds formed on its surface. The anti-reflective film 1 with the anti-glare layer 3 is also called an AG film.

[0032] Figure 2 This is a graph showing the relationship between the angle of light reception and the relative amount of reflected light. It should be noted that... Figure 2 The light angle shown represents the angle of reflected light other than the orthogonal reflected light when the angle of orthogonal reflected light is taken as a reference (0°).

[0033] The maximum value of the relative amount of reflected light with respect to the amount of incident light incident at an angle of incidence of 30° is defined as x, and the maximum value of the relative amount of reflected light with respect to the amount of incident light incident at an angle of incidence of 60° is defined as y. Here, the relative amount of reflected light 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 ​​when the relative amount of reflected light is measured while changing the angle of reception. In addition, the width of the angle of reception (1 / 10 value width) where the relative amount of reflected light is more than 1 / 10 of the maximum value x is defined as α, and the width of the angle of reception (1 / 10 value width) where the relative amount of reflected light is more than 1 / 10 of the maximum value y is defined as β. Figure 2 Show x, y, α, and β.

[0034] The antireflective film of the present invention satisfies the following condition (A).

[0035] β / α ≥ 0.95 (A)

[0036] The value of β / α is one of the indicators of the anti-glare performance of the anti-reflective film when viewed from an oblique direction. Under the condition (A) that is met, the anti-reflective film can maintain the diffusion angle of reflected light even when viewed from an oblique direction. Even if the incident angle increases, the scattering mode is difficult to change, and the anti-glare performance is good when viewed from an oblique direction.

[0037] In addition, the antireflective film of the present invention preferably satisfies the following condition (B).

[0038] y / x≤3.0 (B)

[0039] The value of y / x is one of the indicators of the anti-glare performance of the anti-reflective film when viewed from an oblique direction. Under the condition (B), even if the incident angle increases, the increase in the amount of positively reflected light can be suppressed, and the anti-glare performance is good when viewed from an oblique direction.

[0040] The transmitted image sharpness Ic and haze Ha of the antireflective film of the present invention preferably satisfy the following conditions (C). Here, the transmitted image sharpness 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 according to JIS K7136.

[0041] (100-Ic) / Ha≥5 (C)

[0042] The value of (100-Ic) / Ha is an indicator of the balance between anti-glare and haze. Under the condition (C), it can achieve both high anti-glare and low haze. It should be noted that the haze Ha only needs to be below 20%, and more preferably below 15%.

[0043] The light-transmitting substrate 2 is a film that serves as the base for the anti-reflective film 1, and is formed from a material with excellent visible light transmittance. The material forming the light-transmitting substrate 2 can be 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; transparent resins such as polyimide, polyarylate, polycarbonate, triacetyl cellulose, polyacrylate, polyvinyl alcohol, polyvinyl chloride, cyclic olefin copolymers, norbornene-containing resins, polyethersulfone, and polysulfone, or inorganic glass. The thickness of the light-transmitting substrate 2 is not particularly limited, but is preferably set to 10–200 μm.

[0044] To improve adhesion with other layers in the stack, the surface of the transparent substrate 2 can be modified. Examples of surface modification treatments include alkali treatment, corona treatment, plasma treatment, sputtering treatment, coating with surfactants or silane coupling agents, and Si evaporation.

[0045] The anti-glare layer 3 is a functional layer with finely textured surface that forms the outermost layer of the anti-reflective film 1. The anti-glare layer 3 is formed by coating a coating liquid containing a UV-curable compound, microparticles (fillers), and a photopolymerization initiator onto a light-transmitting substrate 2 and then curing the coating.

[0046] As a UV-curable compound, monofunctional, difunctional, or trifunctional (meth)acrylate monomers can be used, for example. It should be noted that 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 groups.

[0047] 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, tert-butyl (meth)acrylate, glycidyl (meth)acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isobornyl (meth)acrylate, and so on. Isodecanyl acrylate, lauryl acrylate, tridecyl acrylate, hexadecyl acrylate, octadecyl acrylate, benzyl acrylate, 2-ethoxyethyl acrylate, 3-methoxybutyl acrylate, ethyl carbitol acrylate, methacrylate, ethylene oxide modified methacrylate, phenoxy(meth)acrylate, ethylene oxide modified phenoxy(meth)acrylate, propylene 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 acrylate, hydrogenated 2-(meth)acryloyloxyethyl phthalate, hydrogenated 2-(meth)acryloyloxyethyl phthalate 2-(meth)acryloyloxypropyl ester, 2-(meth)acryloyloxypropyl hexahydrogenated phthalic acid, 2-(meth)acryloyloxypropyl tetrahydrogenated phthalic acid, dimethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate, octafluoropropyl (meth)acrylate, and adamantane derivatives of mono(meth)acrylates derived from 2-adamantane and adamantanediol, such as adamantane acrylate and other adamantane derivatives of mono(meth)acrylates.

[0048] Examples of difunctional (meth)acrylates include: ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol dimethacrylate, nonanediol dimethacrylate, ethoxylated hexanediol dimethacrylate, propoxylated hexanediol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, tripropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, neopentyl glycol dimethacrylate, ethoxylated neopentyl glycol dimethacrylate, tripropylene glycol dimethacrylate, hydroxypentyl acid neopentyl glycol dimethacrylate, and other dimethacrylates.

[0049] Examples of trifunctional or higher (meth)acrylates include: trimethylolpropane trimethacrylate, ethoxylated trimethylolpropane trimethacrylate, propoxylated trimethylolpropane trimethacrylate, tris(2-hydroxyethyl)isocyanurate trimethacrylate, glycerol trimethacrylate, etc.; and trifunctional (meth)acrylates such as pentaerythritol trimethacrylate, dipentaerythritol trimethacrylate, and di(trimethylolpropane)methacrylate. Acid ester compounds; polyfunctional (meth) acrylate compounds such as pentaerythritol tetra(meth)acrylate, di(trimethylolpropane) tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, di(trimethylolpropane) penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and di(trimethylolpropane) hexa(meth)acrylate; and polyfunctional (meth) acrylate compounds in which a portion of these (meth) acrylates is substituted with alkyl groups or ε-caprolactones.

[0050] Alternatively, urethane (meth)acrylates can also be used as multifunctional monomers. Examples of urethane (meth)acrylates include those obtained by reacting a product obtained by reacting an isocyanate monomer or prepolymer with a polyester polyol with a (meth)acrylate monomer having hydroxyl groups.

[0051] 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.

[0052] One or more of the aforementioned multifunctional monomers may be used. Furthermore, the aforementioned multifunctional monomers in the coating liquid may be monomers or oligomers formed by partial polymerization.

[0053] Microparticles (fillers) form fine irregularities on the surface of the anti-glare layer 3, giving it the function of diffusing external light. As microparticles, spherical microparticles, microparticles with multiple protrusions, or irregularly shaped microparticles such as porous microparticles can be used. In addition, two or more microparticles with different particle sizes (in the case of irregularly shaped microparticles, the particle size of the nucleus) can also be used.

[0054] Figure 3 This is an SEM image of the anti-glare layer. Figure 4 yes Figure 3 A schematic diagram of the anti-glare layer is shown.

[0055] Figure 3 and Figure 4 The particles shown are generally spherical as a whole. Materials used for the particles include, for example, acrylic resins, polystyrene resins, acrylic-styrene copolymers, polyethylene resins, epoxy resins, silicone resins, polyvinylidene fluoride, and polyvinyl fluoride resins. When two types of particles satisfying conditions (1) to (3) are used as fillers for the anti-glare layer 3, light incident on the anti-glare layer 3 undergoes multiple scattering, thereby improving the anti-glare performance when the anti-reflective film is viewed from an oblique angle.

[0056] Here, the radii of the two types of particles are set as r1 and r2 (refer to...). Figure 4 , where r1 > r2). Radius r1 and r2 are approximate values ​​measured with the microparticles considered as spherical. Radius r1 and r2 are values ​​measured from the SEM image of the cross section of the antireflective film, and are set as the average of the radii of the circles coinciding with the outer peripheries of 100 porous microparticles in the SEM image. Regarding the radii r1 and r2 of the two types of microparticles used in the antireflective film according to this embodiment, the radii r1 and r2 of the two types of microparticles satisfy the following formulas (1), (2), and (3).

[0057] 0.75μm≤r1≤4.0μm···(1)

[0058] 0.10μm≤r2≤1.0μm···(2)

[0059] 0.25μm≤r1-r2 ···(3)

[0060] When the radius r1 of relatively large particles is less than 0.75 μm, the haze decreases, but the anti-glare performance also decreases. When the radius r1 exceeds 4.0 μm, the anti-glare performance increases, but the haze also increases. When the radius r1 of relatively large particles is within the range of formula (1), both high anti-glare and low haze can be achieved. It should be noted that the haze of the antireflective film involved in this invention only needs to be 17% or less, more preferably 15% or less.

[0061] Whether the radius r2 of the relatively small particles is less than 0.10 μm or greater than 1.0 μm, the anti-glare performance of the anti-reflective film decreases when viewed from an oblique angle. That is, whether the radius r2 of the relatively small particles is too large or too small, the light diffusion weakens, and the effect of multiple scattering cannot be fully obtained.

[0062] Figure 5 It is an SEM image of particles with multiple protrusions. Figure 6 It is a schematic diagram of a particle with multiple protrusions.

[0063] Figure 5 The microparticles shown have a spherical core and multiple protrusions extending from the surface of the core. The protrusions on the surface of the microparticles have a shape similar to a portion of a sphere, and the outer surface of the protrusions is approximately spherical. The material used for the microparticles with multiple protrusions can be, for example, acrylic resin or polymethylsilsesquioxane (PMSQ), or may contain particles such as alumina, titanium dioxide, and silicon dioxide.

[0064] Here, the radius of the core is set to r3, and the radius of the protrusion is set to r4 (refer to...). Figure 6 Radius r3 and r4 are approximations determined by treating the nucleus and protrusions as spheres; specifically, they are values ​​calculated as the radius of a circle drawn from any three points on the outer contour of the nucleus and protrusions represented in the SEM image. As an example, in Figure 6 In the diagram, a dashed line represents a circle passing through any three points on the outer contour of a single protrusion.

[0065] The radius r3 of the core is preferably 0.75–4.0 μm, and the radius r4 of the protrusion is preferably 0.05–1.0 μm. Furthermore, the difference between radii r3 and r4 (where r3 > r4) is preferably 0.25 μm or more. With radii r3 and r4 within these ranges, reflected light is easily scattered over a wide area, which is beneficial for improving the anti-glare performance when observing the anti-reflective film from an oblique angle.

[0066] Figure 7 These are SEM images of porous microparticles. Figure 8 yes Figure 7 A magnified image of the porous microparticle surface shown. Figure 7 The dark areas shown correspond to the pores formed on the surface of porous microparticles.

[0067] Porous microparticles are materials that form fine irregularities on the surface of the anti-glare layer 3, giving it the function of diffusing external light. For example... Figure 7 As shown, porous microparticles are particles that are approximately spherical as a whole and have multiple pores on their surface. The material for porous microparticles can be, for example, acrylic resin. When porous microparticles that meet the following conditions (4) and (5) are used as fillers for anti-glare layer 3, light incident on the surface of the porous microparticles undergoes multiple scattering, thereby improving the anti-glare performance when the anti-reflective film is viewed from an oblique angle.

[0068] Here, the radius of the nucleus is set to r5, and the radius of the pores of the porous microparticles is set to r6 (refer to...). Figure 7 and Figure 8 Radius r5 and r6 are approximate values ​​determined by considering the nucleus and pores as spherical. Radius r5 is a value determined from a SEM image of the cross-section of the antireflective film, and is set as the average of the radii of the circles coinciding with the outer peripheries of 100 porous microparticles in the SEM image. r6 is the average radius obtained from the gas desorption isotherm determined according to JIS Z8831-2, based on the pore size distribution obtained from the desorption isotherm using the BJH method. The radii r1 and r6 of the porous microparticles used in the antireflective film according to this embodiment satisfy the following equations (4) and (5).

[0069] 0.75μm≤r5≤4.0μm (4)

[0070] 0.002μm≤r6≤0.010μm (5)

[0071] Figure 11 (a) is a cross-sectional SEM image of the antireflective film using porous microparticles. Figure 11 (b) is an enlarged view of the porous microparticle portion.

[0072] In addition to the methods mentioned above, the following method can also be used to determine the pore radius r6: obtain a SEM image of the cross-section of the antireflective film, regard the black part (concave part) inside the particles contained in the SEM image as the pore, measure the radius of the circle that is most similar to the black part at 100, and calculate the average value at 100.

[0073] When the radius r5 of the core is less than 0.75 μm, the haze decreases, but the anti-glare performance also decreases. When the radius r5 of the core exceeds 4.0 μm, the anti-glare performance increases, but the haze also increases. When the radius r5 of the core is within the range of formula (4), both high anti-glare and low haze can be achieved. It should be noted that the haze of the antireflective film involved in this invention only needs to be 17% or less, more preferably 15% or less.

[0074] When the radius r6 of the pores is less than 0.002 μm, the anti-glare performance of the anti-reflective film decreases when viewed from an oblique angle because the shape of the porous microparticles is close to that of a true sphere. When the radius r6 of the pores exceeds 0.010 μm, it is difficult to obtain a multiple scattering effect, and the anti-glare performance of the anti-reflective film decreases when viewed from an oblique angle.

[0075] As photopolymerization initiators, free radical polymerization initiators such as acetophenone-based, benzophenone-based, thioxanthone-based, benzoin, benzoin methyl ether, and phosphine oxide can be used. Examples of photopolymerization initiators include: diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2,2-diethoxyacetophenone, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-phenylacetophenone, bibenzoyl, benzoin, benzoin methyl ether, benzoin ethyl ether, p-chlorobenzophenone, p-methoxybenzophenone, Michler's ketone, acetophenone, and 2-chlorothioxanthone. These can be used individually or in combination.

[0076] In the composition for forming the anti-glare layer, inorganic microparticles (inorganic nanoparticles) with an average particle size of 10 to 200 nm may also be added as needed.

[0077] Inorganic microparticles function as thickeners to increase the viscosity of the composition used to form the anti-glare layer, and are materials used to regulate the settling or agglomeration of microparticles in the anti-glare layer 3. As inorganic microparticles, silica microparticles, metal oxide microparticles, and various mineral microparticles can be used. For example, colloidal silica or silica microparticles with surface modifications using reactive functional groups such as (meth)acryloyl groups can be used. For example, alumina, zinc oxide, tin oxide, antimony oxide, indium oxide, titanium dioxide, and zirconium oxide can be used. For example, mica, synthetic mica, vermiculite, montmorillonite, iron montmorillonite, bentonite, beidellite, saponite, hectorite, Stevensite, nontronite, Magadiite, illite, Kanemite, layered titanate, smectite, and synthetic smectite can be used. The mineral microparticles can be either natural or synthetic (including substituted products and derivatives), or a mixture of both. Among the mineral microparticles, layered organoclay is preferred. Layered organoclay refers to a substance obtained by introducing organonium ions into the interlayer of bentonite. There are no restrictions on the organonium ions as long as they are substances capable of being organically converted using the cation exchange properties of bentonite. When using layered organoclay minerals, the aforementioned synthetic montmorillonite is preferred as the mineral microparticle.

[0078] In addition, antifouling agents, leveling agents, oleophobic agents, hydrophobic agents, and anti-fingerprint agents can be added to the composition for forming the anti-glare layer as components to improve antifouling properties. Fluorinated compounds or organosilicon compounds can be appropriately used as these additives. Furthermore, various additives such as antistatic agents, defoamers, antioxidants, ultraviolet absorbers, infrared absorbers, colorants, light stabilizers, polymerization inhibitors, and photosensitizers can be added as needed.

[0079] Solvents may be added to the composition for forming the anti-glare layer as needed. One or a mixture of two or more of the following solvents may be used as solvents: alcohols such as methanol, ethanol, 1-propanol, 2-propanol, butanol, isopropanol, and isobutanol; ketones such as acetone, methyl ethyl ketone, cyclohexanone, and methyl isobutyl ketone; ketols such as diacetone alcohol; aromatic hydrocarbons such as benzene, toluene, and xylene; diols such as ethylene glycol, propylene glycol, and hexanediol; diol 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.

[0080] Depending on the requirements, one or more layers of hard coating, high refractive index layer, medium refractive index layer, antistatic layer, electromagnetic wave shielding layer, infrared absorption layer, ultraviolet absorption layer, color correction layer, and other functional layers may be stacked between the light-transmitting substrate 2 and the anti-glare layer 3.

[0081] There are no particular limitations on the coating method for the above-mentioned anti-glare layer forming composition and low refractive index layer forming composition. For example, a spin coater, roller coater, reverse roller coater, gravure coater, micro-gravure coater, air knife coater, bar coater, wire bar coater, die coater, dip coater, sprayer, applicator, etc. can be used for coating.

[0082] As described above, in the anti-reflective film according to this embodiment, the width α of 1 / 10 of the relative value of reflected light quantity with respect to the amount of incident light incident at an incident angle of 30°, and the width β of 1 / 10 of the relative value of reflected light quantity with respect to the amount of incident light incident at an incident angle of 60°, satisfy the above condition (A). That is, the reflected light from light incident at an incident angle of 60° diffuses over a wide range within an angle range that is the same as or greater than that from light incident at an incident angle of 30°. Therefore, in the anti-reflective film according to this embodiment, even if the incident angle increases, the scattering mode is difficult to change, and the anti-glare performance is good when viewed from an oblique angle. According to this embodiment, reflected light can be diffused over a wide range, thus achieving low haze and high anti-glare performance (low image sharpness). Since the anti-reflective film according to this embodiment can achieve both low haze and high anti-glare performance, when used in an image display device, it can suppress the influence of external light reflection and also suppress the reduction of image contrast.

[0083] Anti-glare films that have undergone anti-glare treatment through shaping or contain true spherical fillers in the anti-glare layer have the following problems: the anti-glare performance is high when viewed from the front (within the range of 0 to 30° relative to the normal of the image), but the anti-glare performance is easily reduced when viewed from an oblique angle (within the range of 45° or more relative to the normal of the image) compared to when viewed from the front.

[0084] When using two types of microparticles with different particle sizes as fillers in the anti-glare layer of an anti-reflective film, the dense texture facilitates multiple scattering of incident light. Although the scattering angle is small, the incident light is scattered in multiple directions in a complex manner, thus achieving low haze and high anti-glare performance (low image clarity). Furthermore, by using two types of microparticles with different particle sizes to cause multiple scattering of incident light, the incident light can be effectively scattered even when it is incident from an oblique direction. Since the anti-reflective film according to this embodiment can achieve both low haze and high anti-glare performance, when used in an image display device, it can suppress the influence of external light reflection and also suppress the reduction of image contrast.

[0085] When porous microparticles are used as fillers in the anti-glare layer of an anti-reflective film, the incident light is easily subject to multiple scattering due to the fine pores of the microparticles. Although the scattering angle is small, the incident light can be scattered in multiple directions in a complex manner, thus achieving low haze and high anti-glare performance (low image sharpness). Furthermore, by causing multiple scattering of incident light through porous microparticles, the incident light can be effectively scattered even when it is incident from an oblique direction. Since the anti-reflective film according to this embodiment can achieve both low haze and high anti-glare performance, when used in an image display device, it can suppress the influence of external light reflection and also suppress the reduction of image contrast.

[0086] The anti-reflective film described in this embodiment can be adhered to the outermost surface of an image display panel such as a liquid crystal panel or an organic EL panel to form an image display device. A touch panel can also be disposed between the anti-reflective film and the image display panel. The anti-reflective film described in this embodiment exhibits excellent anti-glare performance when viewed from an oblique angle, thus possessing high anti-glare properties and capable of displaying vivid images. It is suitable for large displays intended for viewing from multiple directions, such as public information displays (PIDs).

[0087] Example

[0088] The following describes specific embodiments of the present invention.

[0089] (Examples 1-1 to 1-5)

[0090] A 40 μm thick triacetyl cellulose (TAC) film was used as the light-transmitting substrate. The anti-glare layer forming composition was prepared by diluting pentaerythritol triacrylate (UV-curable compound), two types of microparticles with different particle sizes (organic fillers), Omnirad (registered trademark) 184 (photopolymerization initiator), organically treated synthetic clay (thickener), leveling agent, and colloidal silica (additive) with a solvent to a suitable coating concentration. The proportions shown in Table 1 are by mass%. The anti-glare layer forming composition was coated onto the light-transmitting substrate in such a manner that the cured film thickness was approximately equal to the particle size of the larger microparticles, and the microparticles were embedded in the anti-glare layer. After drying, the coating was polymerized and cured by UV irradiation to form an anti-glare layer, thereby obtaining the antireflective films according to the various embodiments and comparative examples.

[0091]

[0092] The radii r1 and r2 of the microparticles used in Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-5 were determined as follows. SEM images of the cross-section of the antireflective film were acquired. The shapes of the microparticles contained in the SEM images were considered as spheres, and the radii of the 100 circles that most closely approximate the shape of the microparticles were measured. The average of the radii of the 100 relatively large microparticles was set as r1, and the average of the radii of the 100 relatively small microparticles was set as r2.

[0093] (Ha)

[0094] According to JIS K 7105, the haze was measured using a haze meter (NDH 4000, manufactured by Nippon Denshoku Co., Ltd.).

[0095] (Transmission image sharpness Ic)

[0096] According to JIS K 7105, the sharpness of the transmitted image was measured using a printability measuring instrument (ICM-1T, manufactured by Suga Test Instruments Co., Ltd.) in transmission mode with an optical comb width of 0.5 mm.

[0097] (Relative value of reflected light)

[0098] The relative value of reflected light was measured using a variable angle photometer (Gonio photometer, GP-5, manufactured by Murakami Color Technology Research Institute Co., Ltd.). A black acrylic sheet was attached to the uncoated side of the antireflective film using optical adhesive, serving as the measurement sample. Additionally, as a reference, a sample was prepared by attaching a black acrylic sheet to one side of a translucent substrate (the same side as the uncoated side of the antireflective film) using optical adhesive, with the side matching the coated side of the antireflective film used as the measurement surface.

[0099] The measurement conditions for the angle photometer are set as follows.

[0100] <Measurement Conditions>

[0101] Measurement mode: Reflectance

[0102] • Measurement item: Variable angle

[0103] • VS1 (Aperture on the light source (beam) side): 2.0

[0104] • VS2 (Aperture on the receiving side): 3.0

[0105] • IA (Incident Angle): 30° or 60°

[0106] • FA (Elevation Angle): 0.0°

[0107] • Light reception angle range (RA): Orthographic reflection angle ±20° (when the incident angle is 30°, R1: 10°, R2: 50°; when the incident angle is 60°, R1: 40°, R2: 80°)

[0108] • Sensitivity check: Implementation (Start: R1, End: R2)

[0109] • Neutral density filter: Not used

[0110] • ND filter: Not used

[0111] • Data acquisition interval: 0.1°

[0112] The relative value of reflected light is calculated as follows. First, using a reference measurement surface, the amount of reflected light is measured in 0.1° increments within the aforementioned light-receiving angle range. The measured value of reflected light is set as the relative value (maximum value) of reflected light at the maximum light-receiving angle, and then set to 100. Next, a coefficient is calculated by dividing the maximum value (=100) of the reference relative value of reflected light by the measured value (maximum value) of reflected light. Then, using the coating surface of the antireflective film according to each embodiment and comparative example, the amount of reflected light is measured in 0.1° increments within the aforementioned light-receiving angle range. The product of the measured value of reflected light and the coefficient calculated based on the reference is taken as the relative value of reflected light.

[0113] Calculate the relative values ​​of reflected light for incident angles of 30° and 60° respectively. Define the maximum relative value of reflected light for incident angle 30° as x, and the maximum relative value of reflected light for incident angle 60° as y. Furthermore, plot the incident angle and the calculated relative values ​​of reflected light on a plane with the horizontal axis representing the angle of incidence and the vertical axis representing the relative value of reflected light. Calculate the absolute values ​​(x and y) of the angles of incidence greater than 1 / 10.

[0114] (Anti-glare evaluation)

[0115] Samples were prepared by attaching a black acrylic sheet to the uncoated surface of the antireflective film involved in each embodiment and comparative example using optical adhesive. The anti-glare performance of the antireflective film when viewed from the front, under the condition of being illuminated by fluorescent light from a position 40 cm away from the surface of the antireflective film, is defined as "frontal anti-glare performance". Furthermore, the anti-glare performance of the antireflective film when viewed from the positive reflection direction (a direction tilted 60 degrees relative to the normal of the antireflective film towards the horizontal and opposite to the light source) when illuminated by fluorescent light from a position 40 cm away from the surface of the antireflective film at a 60-degree angle to the horizontal relative to the normal of the antireflective film, is defined as "60-degree anti-glare performance".

[0116] Twenty evaluators visually compared the anti-glare performance of the anti-reflective film at the front and at a 60-degree angle, and scored it according to the following criteria.

[0117] <Evaluation Criteria>

[0118] 4 points: The 60-degree anti-glare performance is the same as the frontal anti-glare performance.

[0119] 3 points: The 60-degree anti-glare performance is slightly lower compared to the frontal anti-glare performance.

[0120] 2 points: The 60-degree anti-glare performance is significantly reduced compared to the frontal anti-glare performance.

[0121] 1 point: Almost no 60-degree anti-glare capability

[0122] The average rating of the 20 participants was categorized according to the following criteria and used as the evaluation value. If the rating is 5 or higher according to the following criteria, the oblique anti-glare performance is good.

[0123] <Evaluation Value>

[0124] Level 6: Above 3.5 and below 4.0

[0125] Level 5: Above 3.0 and below 3.5

[0126] Level 4: Above 2.5 and below 3.0

[0127] Level 3: Above 2.0 and below 2.5

[0128] Level 2: Above 1.5 and below 2.0

[0129] Level 1: 1.0 or higher, 1.5 or lower

[0130] Table 3 shows the particle size, transmitted image clarity, haze, relative value of reflected light, and evaluation value of oblique anti-glare properties of the microparticles used in the anti-reflective films of each embodiment and comparative example.

[0131]

[0132] The anti-reflective films involved in Examples 1-1 to 1-5 suppress haze and have good frontal and 60-degree anti-glare performance because two kinds of microparticles that meet the above conditions (1) to (3) are added to the anti-glare layer.

[0133] The antireflective films involved in Comparative Examples 1-1 and 1-2 had single-size microparticles added to the antiglare layer. The antiglare performance at 60 degrees was significantly reduced in both Comparative Examples 1 and 2. In addition, compared with Examples 1 to 5, the amount of microparticles added was greater, resulting in higher haze and worsening of (100-Ic) / Ha and β / α, which are indicators of low haze and high antiglare performance.

[0134] The antireflective films involved in Comparative Examples 1-3 and 1-4 have higher haze because the radius r1 of the relatively large particles exceeds the upper limit of the above condition (1), and the (100-Ic) / Ha and β / α, which are indicators of low haze and high anti-glare performance, deteriorate.

[0135] The anti-reflective films involved in Comparative Examples 1-5 have poorer anti-glare performance at 60 degrees compared to the Examples because the radius r2 of the relatively small particles exceeds the upper limit of the above condition (2).

[0136] Figure 9 and Figure 10 The graphs are respectively showing the relationship between the light-receiving angle and the relative value of the reflected light amount of the anti-reflective film involved in Example 1-1 and Comparative Example 1-1.

[0137] exist Figure 9 In the antireflective film of Comparative Example 1-1 (using spherical microparticles of one particle size), when the incident angle of the incident light is 60°, the proportion of reflected light components approaching positive reflection is higher compared to the case with an incident angle of 30°. In contrast, in Figure 10In the antireflective film of Example 1-1 (using two types of microparticles with different particle sizes), the amount of positively reflected light was suppressed compared to Comparative Example 1-1, and the reflected light was dispersed over a wider range of light reception angles than in Comparative Example 1. In the antireflective film of Example 1-1, it was confirmed that even with a larger incident angle, multiple scattering of incident light by two types of microparticles with different particle sizes could suppress positively reflected light and achieve high anti-glare performance.

[0138] (Examples 2-1 to 2-4)

[0139] A 40 μm thick triacetyl cellulose (TAC) membrane was used as the light-transmitting substrate. The anti-glare layer forming composition was prepared by diluting 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) with a solvent to a suitable coating concentration. The proportions shown in Table 1 are by mass%. The anti-glare layer forming composition was coated onto the light-transmitting substrate in such a manner that the cured film thickness was approximately equal to the diameter of the porous microparticle core, and the core was embedded in the anti-glare layer thickness. After drying, the coating was polymerized and cured by UV irradiation to form the anti-glare layer, thereby obtaining the antireflective films according to the various embodiments and comparative examples.

[0140]

[0141] The radius r5 of the nucleus of the microparticles used in Examples 2-1 to 2-4 and Comparative Examples 2-1 to 2-5 was measured as follows. SEM images of the cross-section of the antireflective film were obtained. The shape of the microparticles contained in the SEM image was regarded as a sphere. The radius of the circle that most closely approximates the shape of the microparticle at 100 points was measured, and the average value was set as r5.

[0142] Furthermore, the pore radius r6 of the porous microparticles used in Examples 1-4 and Comparative Examples 3-5 was measured according to JIS Z8831-2 as follows. First, the container containing the porous microparticles was heated at 65°C while being purged with nitrogen for 20 minutes. After cooling to room temperature, the container containing the porous microparticles was heated at 65°C while being degassed under vacuum until the pressure inside the container reached below 0.05 mmHg. Next, the nitrogen desorption isotherm of the porous microparticles was measured using an automatic surface area / pore distribution measuring device (Shimadzu Corporation, Tristar 3030). The nitrogen desorption isotherm was measured using nitrogen as the adsorbate, with an adsorbate cross-sectional area of ​​0.162 nm. 2Under the specified conditions, the nitrogen desorption isotherm was analyzed using the constant volume method. The software accompanying the automatic specific surface area / pore distribution measuring device was used to analyze the nitrogen desorption isotherm using the BJH method, and the calculated average pore radius was set as r6.

[0143] The haze Ha, transmitted image clarity Ic, maximum value x of the relative amount of reflected light when the incident light is 30°, maximum value y of the relative amount of reflected light when the incident light is 60°, the width α and β (absolute value) of the light reception angle where x and y are 1 / 10 or more, and the anti-glare evaluation value of the anti-reflective film involved in each embodiment and comparative example were obtained by the same method as in Examples 1-1 to 1-5.

[0144] Table 4 shows the evaluation values ​​of the shape and size of the organic filler used in the antireflective films of each embodiment and comparative example, the clarity of the transmitted image, the haze, the relative value of the reflected light, and the evaluation value of the oblique anti-glare performance.

[0145]

[0146] The anti-reflective films involved in Examples 2-1 to 2-4 suppress haze and have good frontal and 60-degree anti-glare performance because porous microparticles satisfying the above conditions (4) and (5) are added to the anti-glare layer.

[0147] The anti-glare films involved in Comparative Examples 2-1 and 2-2 exhibited good frontal anti-glare performance, but due to the use of spherical microparticles, the 60° anti-glare performance was significantly reduced. Furthermore, compared to Examples 2-1 to 2-4, the amount of microparticles added was higher, resulting in poorer 60° anti-glare performance. Additionally, the haze increased, and the (100-Ic) / Ha ratio, an indicator of low haze and high anti-glare performance, also deteriorated. In Comparative Example 2-1, the y / x value also deteriorated.

[0148] Although the anti-reflective films involved in Comparative Examples 2-3 and 2-4 had porous microparticles added to the anti-glare layer, they did not meet the above condition (4), so the haze was high and the (100-Ic) / Ha, which is an indicator of low haze and high anti-glare performance, was also worse.

[0149] Although the anti-reflective film involved in Comparative Examples 2-5 added porous microparticles to the anti-glare layer, its anti-glare performance at 60° deteriorated because it did not meet the above condition (5). In addition, (100-Ic) / Ha, which is an indicator of low haze and high anti-glare performance, also deteriorated.

[0150] Figure 12 This is a graph showing the relationship between the light-receiving angle and the relative value of the reflected light amount of the antireflective film involved in Example 2-1. It should be noted that, since Comparative Example 2-1, which uses spherical microparticles as filler, is the same as Comparative Example 1-1 described above, it will be discussed below... Figure 12 The graph of Example 2-1 shown is similar to... Figure 10 The graphs of Comparative Example 1-1 are compared.

[0151] exist Figure 10 In the antireflective film of Comparative Example 1-1 (using spherical microparticles), when the incident angle of the incident light is 60°, the proportion of reflected light components approaching positive reflection is higher compared to the case with an incident angle of 30°. In contrast, in Figure 12 In the antireflective film of Example 2-1 (using porous microparticles), the amount of positively reflected light was suppressed compared to Comparative Example 1, and the reflected light was dispersed over a wider range of light reception angles than in Comparative Example 1-1 (Comparative Example 2-1). In the antireflective film of Example 2-1, it was confirmed that even with a larger incident angle, multiple scattering of incident light by porous microparticles can suppress positively reflected light and achieve high anti-glare performance.

[0152] Industrial applicability

[0153] This invention can be used as an anti-reflective film for image display devices, etc.

[0154] Explanation of symbols

[0155] 1. Anti-reflective film

[0156] 2. Translucent substrate

[0157] 3 Anti-glare layer

Claims

1. An anti-reflective film, characterized in that, When the maximum value of the relative amount of reflected light with respect to the incident light at an incident angle of 30° is set as x, the maximum value of the relative amount of reflected light with respect to the incident light at an incident angle of 60° is set as y, the width of the receiving angle whose relative amount of reflected light is more than 1 / 10 of the maximum value of x is set as α, and the width of the receiving angle whose relative amount of reflected light is more than 1 / 10 of the maximum value of y is set as β, the following equation (A) is satisfied: β / α≥0.95 （A）。 2. The antireflective film according to claim 1, characterized in that, When the maximum value of the reflected light quantity relative to the incident light quantity incident at an angle of incidence of 30° is set as x, and the maximum value of the reflected light quantity relative to the incident light quantity incident at an angle of incidence of 60° is set as y, the following equation (B) is satisfied: y / x≤3.0 (B).

3. The antireflective film according to claim 1, characterized in that, For a 0.5mm comb width, the image sharpness Ic and haze Ha of the transmitted image satisfy the following formula (C): (100-Ic) / Ha≥5 (C).

4. The antireflective film according to claim 1, characterized in that, It has a light-transmitting substrate and one or more optical functional layers stacked on the light-transmitting substrate. At least one surface of the optical functional layer has an uneven shape. The optical functional layer contains two types of microparticles with different particle sizes. The radii r1 and r2 of the two types of particles satisfy the following equations (1), (2), and (3): 0.75μm≤r1≤4.0μm···(1) 0.10μm≤r2≤1.0μm···(2) 0.25μm≤r1-r2···(3).

5. The antireflective film according to claim 1, characterized in that, It has a light-transmitting substrate and one or more optical functional layers stacked on the light-transmitting substrate. At least one surface of the optical functional layer has an uneven shape. The optical functional layer contains porous microparticles. The radius r5 of the core of the porous microparticle and the radius r6 of the surface pores of the porous microparticle satisfy the following equations (4) and (5): 0.75μm≤r5≤4.0μm (4) 0.002μm≤r6≤0.010μm (5).

6. An image display device comprising: Image display panel, and The antireflective film according to claim 1.

Images