Anti-glare film and image display device using the same

Abstract

To provide an anti-glare film capable of achieving both anti-glare properties and glaring-resistant properties even when used in a high-definition image display device and the image display device using the same.SOLUTION: There is provided an anti-glare film which comprises at least one anti-glare layer laminated on a transparent substrate and has an uneven shape on its outermost surface. The anti-glare film is characterized in that the number of protrusions having an arithmetic mean height Sa or more present on the outermost surface measured by an optical interference method is 600 or more per measurement area.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an antiglare film that reduces reflection of external light and an image display device using the same.

Background Art

[0002] An antiglare film (also referred to as an anti-glare (AG) film) has an antiglare layer in which an inorganic material or a filler is dispersed in a resin layer on a transparent substrate. The antiglare film scatters surface reflected light due to the uneven shape of the outermost surface and blurs the image of the reflected external light, thereby improving visibility. Compared with an antireflection film that has no unevenness on the outermost surface and prevents reflection by utilizing light interference, the antiglare film has less reflection of images such as people and backgrounds, and thus when used in an image display device, it is possible to clearly view the displayed image.

[0003] In recent years, with the increasing definition of image display devices, improvement in the glare property of antiglare films has been demanded. For example, Patent Document 1 describes an antiglare film in which when the three-dimensional arithmetic mean roughness of the surface of the antiglare layer satisfies a predetermined condition, glare can be suppressed and a decrease in contrast can be suppressed even when used in a high-definition image display device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The antiglare property of an antiglare film can be improved by increasing the number of unevennesses on the outermost surface or increasing the size of the unevennesses. However, due to an increase in the lens effect caused by the uneven shape of the outermost surface, the anti-glare property deteriorates. That is, in an antiglare film, there is a trade-off relationship between the antiglare property obtained by the uneven shape of the outermost surface and the anti-glare property.

[0006] Therefore, an object of the present invention is to provide an antiglare film capable of achieving both antiglare property and anti-glitter property even when used in a high-definition image display device, and an image display device using the same.

Means for Solving the Problems

[0007] The antiglare film according to an embodiment of the present invention has at least one antiglare layer laminated on a transparent substrate, has an uneven shape on the outermost surface, and the number of convex portions having an arithmetic mean height Sa or more present on the outermost surface, measured by the optical interference method, is 600 or more per measurement area.

[0008] The antiglare film according to another embodiment of the present invention has at least one antiglare layer laminated on a transparent substrate, has an uneven shape on the outermost surface, and when the convex portions are cut by a plane parallel to the average plane of the uneven shape and having a height equal to the arithmetic mean height Sa from the average plane, the number of convex portions having a cross-sectional area of less than 150 μm 2 is 480 or more per measurement area.

[0009] The display device according to the present invention includes any one of the above antiglare films.

Effects of the Invention

[0010] According to the present invention, it is possible to provide an antiglare film capable of achieving both antiglare property and anti-glitter property even when used in a high-definition image display device, and an image display device using the same.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0012] FIG. 1 is a cross-sectional view schematically showing an example of an antiglare film according to an embodiment.

[0013] The antiglare film 11 includes a transparent substrate 2 and an antiglare layer 3 laminated on one surface of the transparent substrate 2. The antiglare film 11 is an optical film (also referred to as an "AG film") that scatters incident light with the fine uneven shape on the surface of the antiglare layer 3 to suppress the reflection of external light.

[0014] The transparent substrate 2 is a film that serves as the base of the antiglare film 11 and is formed of a material having excellent visible light transmittance. As the forming material of the transparent substrate 2, 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, polyimide, polyarylate, polycarbonate, triacetyl cellulose, polyacrylate, polyvinyl alcohol, polyvinyl chloride, cycloolefin copolymer, norbornene-containing resin, transparent resins such as polyethersulfone and polysulfone, and inorganic glass can be used. The thickness of the transparent substrate 2 is not particularly limited, but is preferably 10 to 200 μm.

[0015] The surface of the transparent substrate 2 may be subjected to a surface modification treatment in order to improve the adhesion to other layers to be laminated. Examples of the surface modification treatment include alkali treatment, corona treatment, plasma treatment, sputtering treatment, application of a surfactant or a silane coupling agent, and Si deposition.

[0016] The antiglare layer 3 is a functional layer that forms the fine uneven shape on the outermost surface of the antiglare film 11 and contains fine particles (shown as circles in the drawing). The film thickness of the antiglare layer 3 is not particularly limited, but is preferably 1.3 to 5.0 μm.

[0017] The antiglare layer 3 is formed by applying a coating liquid containing an active energy ray curable compound and fine particles (organic filler) to the transparent substrate 2 and curing the coating film.

[0018] As the active energy ray-curable compound, for example, monofunctional, bifunctional or trifunctional or higher (meth)acrylate monomers can be used. In the present specification, “(meth)acrylate” is a general term for both acrylate and methacrylate, and “(meth)acryloyl” is a general term for both acryloyl and methacryloyl. The (meth)acrylate monomer may contain fluorine.

[0019] Examples of monofunctional (meth)acrylates 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, isobornyl (meth)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, phosphoric acid (meth)acrylate, ethylene oxide-modified phosphoric acid (meth)acrylate, 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, methoxypolythylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 2-(meth)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,Examples of adamantyl acrylate derivatives mono(meth)acrylates such as adamantyl acrylate having a monovalent mono(meth)acrylate derived from adamantane diol can be mentioned.

[0020] 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, hydroxypivalic acid neopentyl glycol di(meth)acrylate and the like.

[0021] Examples of (meth)acrylates having three or more functional groups 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, glycerin tri(meth)acrylate, etc., trifunctional (meth)acrylate compounds such as pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, etc., polyfunctional (meth)acrylate compounds having three or more functional groups 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, ditrimethylolpropane hexa(meth)acrylate, etc., and polyfunctional (meth)acrylate compounds in which a part of these (meth)acrylates is substituted with an alkyl group or ε-caprolactone.

[0022] Also, urethane (meth)acrylate can be used as a polyfunctional monomer. Examples of urethane (meth)acrylate include those obtained by reacting a (meth)acrylate monomer having a hydroxyl group with a product obtained by reacting a polyester polyol with an isocyanate monomer or prepolymer.

[0023] Examples of urethane (meth)acrylate 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, dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer, and the like.

[0024] One of the above-mentioned polyfunctional monomers may be used, or two or more thereof may be used in combination. Further, the above-mentioned polyfunctional monomer may be a monomer in the coating liquid, or may be an oligomer in which a part has been polymerized.

[0025] The fine particles (organic filler) mainly form fine irregularities on the surface of the antiglare layer 3 and are materials that impart a function of diffusing external light. As the organic filler, resin particles made of a light-transmitting resin material such as acrylic resin, polystyrene resin, styrene-(meth)acrylate copolymer, polyethylene resin, epoxy resin, silicone resin, polyvinylidene fluoride, and polyfluoroethylene resin can be used. In order to adjust the refractive index and the dispersion of the resin particles, two or more types of resin particles having different materials (refractive indices) may be mixed and used. The average particle size of the organic filler is preferably 0.5 to 5.5 μm. When the average particle size of the organic filler exceeds 5.5 μm, if the mass of the organic filler is constant, the number of particles is smaller than when the average particle size of the organic filler is 5.5 μm or less, so the number of convex portions formed is reduced and the anti-glitter property tends to decrease. The refractive index of the organic filler is preferably 1.495 to 1.595, although it depends on the refractive index of the binder resin (active energy ray curable resin). Further, the blending amount of the organic filler is preferably 2 to 20% by mass of the total solid content of the composition for forming the antiglare layer, although it depends on the particle size.

[0026] The anti-glare layer forming composition may further contain inorganic fine particles. The inorganic fine particles added to the anti-glare layer forming composition are preferably nanoparticles with an average particle size of 10 to 200 nm.

[0027] The inorganic fine particles are mainly materials for adjusting the sedimentation and aggregation of the fine particles (organic fillers) in the anti-glare layer 3. As the inorganic fine particles, silica fine particles, metal oxide fine particles, various mineral fine particles, etc. can be used. As the silica fine particles, for example, colloidal silica, silica fine particles surface-modified with reactive functional groups such as (meth)acryloyl groups, etc. can be used. As the metal oxide fine particles, for example, alumina, zinc oxide, tin oxide, antimony oxide, indium oxide, titania, zirconia, etc. can be used. As the mineral fine particles, for example, mica, synthetic mica, vermiculite, montmorillonite, iron montmorillonite, bentonite, beidellite, saponite, hectorite, stevensite, nontronite, magadiite, illite, kanemite, layered titanic acid, smectite, synthetic smectite, etc. can be used. The mineral fine particles may be either natural products or synthetic products (including substituents and derivatives), and a mixture of both may be used. Among the mineral fine particles, layered organic clay is more preferable. The layered organic clay refers to a material in which organic onium ions are introduced between the layers of swellable clay. The organic onium ions are not limited as long as they can be organicized by utilizing the cation exchangeability of the swellable clay. When using layered organic clay minerals as the mineral fine particles, the above-mentioned synthetic smectite can be preferably used. The synthetic smectite has a function of increasing the viscosity of the anti-glare layer forming composition, suppressing the sedimentation of resin particles and inorganic fine particles, and adjusting the uneven shape on the surface of the optical functional layer.

[0028] In order to cure the anti-glare layer-forming composition by ultraviolet irradiation, a polymerization initiator may be added. As the polymerization initiator, a polymerization initiator that generates radicals by ultraviolet irradiation can be used. As the polymerization initiator, it can be used in radical polymerization initiators such as acetophenone-based, benzophenone-based, thioxanthone-based, benzoin, benzoin methyl ether, acylphosphine oxide, etc. As the polymerization initiator, for example, 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, 2-chlorothioxanthone, etc. can be used. Among these, one kind may be used alone, or two or more kinds may be used in combination.

[0029] In addition, to the anti-glare layer-forming composition, as components for improving antifouling properties, it is preferable to add an antifouling agent, a leveling agent, an oil repellent, a water repellent, and a fingerprint adhesion preventing agent. As these additives, fluorine-containing compounds and silicone compounds can be preferably used. By adding an antifouling compound to the outermost anti-glare layer 3, the fingerprint wiping property can be further improved. In addition, various additives such as an antistatic agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, an infrared absorber, a coloring material, a light stabilizer, a polymerization inhibitor, a photosensitizer, etc. may be added as necessary.

[0030] Furthermore, a solvent may be added to the anti-glare layer forming composition, if necessary. As the solvent, one or more of the following can be used alone or in combination: 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; N-methylpyrrolidone, dimethylformamide, etc.

[0031] FIG. 2 is a cross-sectional view schematically showing another example of the optical film according to the embodiment.

[0032] The anti-glare film 12 includes a transparent substrate 2, an anti-glare layer 3 laminated on one surface of the transparent substrate 2, and a low refractive index layer 4 laminated on the surface of the anti-glare layer 3 and having a lower refractive index than the anti-glare layer 3. The anti-glare film 12 is an optical film that suppresses the reflection and reflection of external light by utilizing the scattering of incident light and optical interference due to fine irregularities on the outermost surface (also referred to as an "AGLR film").

[0033] As the transparent substrate 2, a film made of the above-described forming material can be used. The anti-glare layer 3 can be formed by applying the above-described anti-glare layer forming composition to one surface of the transparent substrate 2 and drying and curing it.

[0034] The low refractive index layer 4 has a refractive index lower than that of the underlying anti-glare layer 3 and is a functional layer that suppresses reflection by optical interference. The film thickness of the low refractive index layer 4 is not particularly limited, but is preferably 100 to 120 nm.

[0035] The low refractive index layer 4 can be formed by applying a composition containing an active energy ray curable compound onto the surface of the antiglare layer 3 and curing the coating film. The low refractive index layer 4 may contain low refractive index fine particles for adjusting the refractive index.

[0036] Examples of the low refractive index fine particles include LiF, MgF2, NaF, AlF 3、 Na3AlF 6、 Fine particles such as SiO2 can be used. As the silica particles, silica fine particles having voids inside can be preferably used. Since the refractive index of the void part of the silica fine particles having voids inside can be set to the refractive index of air (about 1), it is advantageous for reducing the refractive index of the low refractive index layer 4. Specifically, porous silica particles and silica particles having a shell structure can be used. Note that the low refractive index fine particles are not necessarily required, and when the refractive index after curing of the active energy ray curable compound is lower than the refractive index of the antiglare layer 3, the low refractive index fine particles may be omitted.

[0037] As the active energy ray curable compound, the polymerizable compounds described in the antiglare layer can be used. Further, a polymerization initiator and a solvent described above may be appropriately added to the composition for forming the low refractive index layer.

[0038] Since the low refractive index layer 4 is the outermost functional layer, it is preferable to add an antifouling agent, a leveling agent, an oil repellent, a water repellent, and a fingerprint adhesion preventing agent as components for improving antifouling properties to the composition for forming the low refractive index layer. As these additives, fluorine-containing compounds and silicone compounds can be preferably used. In addition, various additives such as an antistatic agent, an antifoaming agent, an antioxidant, an ultraviolet absorber, an infrared absorber, a coloring material, a light stabilizer, a polymerization inhibitor, and a photosensitizer may be added as necessary.

[0039] 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 shielding layer, an infrared absorption layer, an ultraviolet absorption layer, and a color correction layer may be laminated between the transparent substrate 2 and the antiglare layer 3.

[0040] The coating method of the above anti-glare layer-forming composition and low refractive index layer-forming composition is not particularly limited. For example, it can be coated using a spin coater, roll coater, reverse roll coater, gravure coater, micro gravure coater, knife coater, bar coater, wire bar coater, die coater, dip coater, spray coater, applicator, etc.

[0041] Here, the details of the surface uneven shape of the anti-glare film according to this embodiment will be described. The anti-glare film according to this embodiment satisfies at least one of the following conditions (A) and (B).

[0042] Condition (A): The number of convex portions present on the outermost surface and having a height of at least the arithmetic mean height Sa is 600 or more per measurement area.

[0043] The number of convex portions having a height of at least the arithmetic mean height Sa can be obtained by measuring the outermost surface of the anti-glare film by the optical interference method and analyzing it with the analysis software of the measuring device. When the measurement area is measured under the measurement conditions of the examples described later, it is 701.826×936.116 μm 2 (≒0.662 m 2 )). The arithmetic mean height Sa is a value measured in accordance with ISO 25178-2 (2007) and 25178-3-2 (2010), and is defined as the average value of the absolute values of the heights of the convex portions from the average plane when the average plane of all the unevenness existing in the measurement region is used as a reference.

[0044] In this embodiment, the number of convex portions defined in the above condition (A) is represented as the number of convex portions per measurement area set under the measurement conditions of the examples described later. However, when the number of convex portions having a height of at least Sa is represented as the number per area different from the measurement area of this embodiment, it is sufficient that the number of convex portions converted to the number of the measurement area of this embodiment is 600 or more.

[0045] When the number of convex portions defined in the above condition (A) is 600 or more per measurement area, it is possible to reduce the glare even when used in, for example, a high-definition image display device with 210 ppi or more while ensuring high anti-glare properties. The number of convex portions having a height equal to or higher than the arithmetic mean height Sa present on the outermost surface is a parameter having a correlation with the anti-glare property, and the anti-glare property improves as the number increases. The upper limit of the number of convex portions having a height equal to or higher than the arithmetic mean height Sa present on the outermost surface is not particularly limited, but it may be 2000 or less per measurement area, or it may be 1850 or less per measurement area.

[0046] Condition (B): When the convex portions are cut by a plane parallel to the average plane of the uneven shape of the outermost surface and having a height equal to the arithmetic mean height Sa from the average plane, the number of convex portions having a cross-sectional area of less than 150 μm 2 is 480 or more per measurement area.

[0047] The cross-sectional area when the convex portions are cut by a plane having a height equal to the arithmetic mean height Sa from the average plane is less than 150 μm 2 The number of the convex portions is a value obtained by measuring the outermost surface of the anti-glare film by an optical interference method and performing analysis with the analysis software of the measuring device. The measuring methods of the measurement area and the arithmetic mean height Sa are the same as those described in condition (A).

[0048] In the present embodiment, the number of convex portions defined in the above condition (B) is represented as the number per measurement area set under the measurement conditions of the examples described later. However, when the number of convex portions having a cross-sectional area of less than 150 μm 2 when cut by a plane having a height equal to the arithmetic mean height Sa from the average plane is represented as the number per area different from the measurement area of the present embodiment, it is sufficient that the value obtained by converting the number per the different area into the number per the measurement area of the present embodiment is 480 or more.

[0049] When the number of convex portions defined in the above condition (B) is 480 or more per measurement area, it is possible to reduce glare even when used in a high-definition image display device with, for example, 210 ppi or more while ensuring high anti-glare properties. The cross-sectional area of the convex portion cut by a plane having a height equal to the arithmetic mean height Sa from the average plane is 150 μm 2 The number of convex portions having a cross-sectional area of less than 150 μm is a parameter having a correlation with anti-glare property, and the anti-glare property improves as the number increases. The cross-sectional area of the convex portion cut by a plane having a height equal to the arithmetic mean height Sa from the average plane is 150 μm 2 The upper limit of the number of convex portions having a cross-sectional area of less than 150 μm is not particularly limited, but it may be 2000 or less per measurement area, or it may be 1700 or less per measurement area.

[0050] The number of convex portions defined in the above conditions (A) and (B) can be controlled, for example, by the particle size and addition amount of the filler added to the anti-glare layer 3, the amount of the additive, the film thickness of the anti-glare layer 3, and the adjustment of the aggregation state of the filler in the film-forming process.

[0051] Further, it is preferable that the transmitted image sharpness of the anti-glare film according to the present embodiment is 92% or less. The transmitted image sharpness is a value measured using an optical comb with a width of 0.5 mm in accordance with JIS K 7374 (2007). When the transmitted image sharpness of the anti-glare film exceeds 92%, the action of scattering light on the outermost surface is weak, and it is not preferable because the reflection of external light cannot be sufficiently reduced.

[0052] Further, it is preferable that no glare is visually recognized when observing the light source in a state where the anti-glare film according to the present embodiment is stacked on a black matrix having a fineness of 210 ppi or more. When glare is visually recognized when observing the light source after stacking on a black matrix of less than 210 ppi, it is not suitable for use as an anti-reflection film for recent high-definition image display devices.

[0053] The anti-glare film according to this embodiment can be used to form an image display device by being laminated on 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-glare film and the image display panel. Since the anti-glare film according to this embodiment is excellent in anti-glare property and anti-glitter property, it is suitable as an optical film provided on the outermost surface of an image display device, particularly a high-definition image display device with 210 ppi or more.

Example

[0054] Hereinafter, examples of specifically implementing the present invention will be described.

[0055] (Composition for forming the first layer) An anti-glare layer (AG) or a clear hard coat layer (CHC) was formed as the first layer on a transparent substrate. The materials used in the composition for forming the first layer are shown below.

[0056] 1. Actinic energy ray curable resin Light acrylate PE-3A (trade name), Kyoeisha Chemical Co., Ltd., pentaerythritol triacrylate

[0057] 2. Photoinitiator Omnirad (registered trademark) 184 (trade name), IGM Resins B.V., 1-hydroxycyclohexyl-phenyl ketone

[0058] 3. Organic filler (fine particles) (1) Resin particle 1: diameter 1.5 μm, refractive index 1.495 (2) Resin particle 2: diameter 2.0 μm, refractive index 1.516 (3) Resin particle 3: diameter 3.4 μm, refractive index 1.564 (4) Resin particle 4: diameter 3.5 μm, refractive index 1.515 (5) Resin particle 5: diameter 3.5 μm, refractive index 1.590 (6) Resin particle 6: diameter 3.5 μm, refractive index 1.564 (7) Resin particle 7: diameter 5.3 μm, refractive index 1.544

[0059] 4. Thickener Smeton SAN (trade name), Kunimine Industries Co., Ltd., organically synthesized hectorite

[0060] 5. Levelling agent Megafac (registered trademark) F565 (trade name), DIC Corporation

[0061] 6. Additive MEK-ST-40 (trade name), Nissan Chemical Industries, Ltd., organosilica sol

[0062] 7. Solvent Toluene

[0063] (Composition for forming the second layer) In Examples 3 and 4, a low refractive index layer (LR) with a film thickness of 120 nm was formed as the second layer on the antiglare layer. The materials used in the composition for forming the second layer are shown below.

[0064] 1. Actinic energy ray curable resin (1) Light acrylate PE-3A (trade name), Kyoeisha Chemical Co., Ltd., pentaerythritol triacrylate (described as "PE-3A" in the table) (2) Fluorine-containing acrylate, Kyoeisha Chemical Co., Ltd.

[0065] 2. Photopolymerization initiator Omnirad (registered trademark) 184 (trade name), IGM Resins B.V., 1-hydroxycyclohexyl-phenyl ketone

[0066] 3. Hollow silica fine particles Porous silica fine particles (diameter 75 nm), JGC Catalysts and Chemicals Ltd.

[0067] 4. Levelling agent Megafac RS-75 (trade name), DIC Corporation

[0068] 5. Solvent Mesoisobutyl ketone

[0069] (Examples 1, 2, 4 to 6 and Comparative Examples 1 to 6) The composition for forming the first layer having the composition described in Tables 1 and 2 was prepared. The composition for forming the first layer was diluted with a solvent to a concentration suitable for coating. The composition for forming the first layer was applied to one surface of a triacetyl cellulose (TAC) film having a thickness of 40 μm, dried, and then the coating film was polymerized and cured by ultraviolet irradiation to form the first layer (AG or CHC), and samples according to Examples 1, 2, 4 to 6 and Comparative Examples 1 to 6 were obtained. The composition for forming the first layer was applied so that the film thickness of the first layer (antiglare layer) after curing was the film thickness described in Table 4.

[0070] (Examples 3 and 4) The composition for forming the first layer having the composition described in Tables 1 and 2 was prepared. Also, the composition for forming the second layer having the composition described in Table 3 was prepared. The composition for forming the first layer and the composition for forming the second layer were diluted with a solvent to a concentration suitable for coating. The composition for forming the first layer was applied to one surface of a triacetyl cellulose (TAC) film having a thickness of 40 μm, dried, and then the coating film was polymerized and cured by ultraviolet irradiation to form the first layer (AG). The composition for forming the first layer was applied so that the film thickness of the first layer (antiglare layer) after curing was the film thickness described in Table 4. Next, the composition for forming the second layer was applied onto the formed first layer, dried, and then the coating film was polymerized and cured by ultraviolet irradiation to form the second layer (LR), and samples according to Examples 3 and 4 were obtained. The composition for forming the second layer was applied so that the film thickness of the second layer (low refractive index layer) after curing was 120 nm.

[0071] Tables 1 to 3 show the compositions of the coating liquids for each example and each comparative example. The ratios shown in Tables 1 to 3 are in mass %.

[0072] [Table 1]

[0073] [Table 2]

[0074] [Table 3]

[0075] The samples according to each example and each comparative example were evaluated as follows.

[0076] [Surface uneven shape] Using a non-contact surface / layer cross-sectional shape measurement system (Vertscan VS1330, Hitachi Systems, Ltd.), three-dimensional data of the uneven shape of the outermost surface of each sample was measured by the optical interference method. The measurement conditions are as follows. [Optical conditions] · Camera: Sony Corporation HR-50 1 / 3 inch · Camera speed: 1.0X · Objective lens magnification: 10XDI (10 times) · Imaging lens (lens barrel): 0.5 times · Zoom lens: 1 time · Light source / wavelength filter: 520 nm · ND filter: Not used · A-Stop (aperture stop): Not used (fully open) · F-Stop (field stop): Not used (fully open) [Measurement conditions] · Measurement device: Piezo · Measurement mode: Phase · Scan speed: 4 μm / sec · Field of view size: 640 × 480 pixels · Scan range: 10 μm to -10 μm · Effective pixel number: 50% · Average number of times: 1 time · Measurement range: 701.826 μm × 936.116 μm (automatically determined by setting the objective lens to 10XDI (10 times))

[0077] The raw profile data (three-dimensional height data of unevenness) obtained by measurement was converted and analyzed using the analysis software (VS-Viewer10, Hitachi High-Tech Corporation) attached to the measuring device, and the arithmetic mean height Sa, the number of convex portions with a height of Sa or more from the average plane, and the cross-sectional area of the convex portion cut by a plane parallel to the average plane and having a height of Sa from the average plane were 150 μm 2 The number of convex portions less than this was calculated. The specific setting conditions in the analysis software are shown below.

[0078] First, based on the following conversion conditions, processing was performed in the order of filter, surface correction, and interpolation. Note that the filter processing is for removing noise components from the measurement data, the surface correction processing is for removing the inclination of the sample, and the interpolation is for predicting and interpolating the portions where measurement values could not be obtained due to optical interference during measurement using surrounding data. <Conversion Conditions> · Filter Type: Median (3×3) Boundary Processing: Expand the target and interpolate the edge portion · Surface Correction: Fourth order · Interpolation: Complete interpolation

[0079] Using the ISO parameter function of the analysis software, the arithmetic mean height Sa was calculated under the following processing conditions. <Processing Conditions> · S-Filter: Automatic (a value automatically set according to the objective lens, which is 0.455 μm in the examples and comparative examples) · Normal probability paper Number of divisions: Arbitrary Upper limit of calculation range: Arbitrary Value of calculation range: Arbitrary Parameter: Select "Height Paramters" Output: Select "Parameter List"

[0080] Fourier transform was performed on the data after the conversion process under the above conversion conditions. After extracting the short-wavelength components from the obtained spectral data using a band-pass filter, the inverse Fourier transform was performed on the extracted spectral data to obtain an analysis image. The Fourier transform conditions are shown below. <Fourier transform conditions> · Analysis: Frequency filtering · Filter: Band-pass filter 0.8 μm to 50 μm · Output: Spectral image and analysis image (however, the spectral image can be omitted)

[0081] Using the particle analysis function (protrusion analysis) of the analysis software attached to the measuring device, the analysis image obtained by inverse Fourier transform was analyzed. The number of all convex parts shown in the analysis result was taken as the number of convex parts with a height from the average plane greater than or equal to the arithmetic mean height Sa. Also, among all the convex parts shown in the analysis result, the number of convex parts with an area (cross-sectional area in a plane at the height threshold) less than 150 μm 2 was counted, and the cross-sectional area of the convex parts cut by a plane parallel to the average plane and having a height of Sa from the average plane was less than 150 μm 2 was taken as the number of convex parts. <Particle analysis conditions> · Analysis: Protrusion analysis · Image correction: None · Processing: Set the arithmetic mean roughness Sa calculated above as the height threshold · Target determination: Set so that all particles are analysis targets · Histogram: Arbitrary · Output: Select "Analysis image", "Particle histogram", and "Parameter list"

[0082] [Transmission image sharpness] The transmission image sharpness was measured in transmission mode with an optical brush width of 0.5 mm using an image mapping measuring instrument (ICM-1T, Suga Test Instruments Co., Ltd.) in accordance with JIS K 7374:2007.

[0083] [Anti-glitter property] The non-coated surface of each sample was bonded to a plate glass (thickness 0.8 - 1.0 mm) using a transparent adhesive. A black matrix with a predetermined fineness was placed on an LED light box, and the sample bonded to the plate glass was placed on the black matrix such that the plate glass was in contact with the black matrix. With the LED light box lit, the glass-bonded sample was rotated, and the sample was observed from a position 30 cm directly above. The presence or absence of glare was visually determined. Multiple glare observations were performed while increasing the fineness of the black matrix (increasing the ppi value), and the maximum fineness (the highest ppi value) at which glare was not visually recognized was taken as the anti-glare resistance score. If the score was 210 ppi or higher, it was determined that the anti-glare resistance was good.

[0084] [Anti-reflection property] The non-coated surface of each sample was bonded to a black acrylic plate (hereinafter referred to as "black board") using a transparent adhesive. With the coated surface of the black board-bonded sample facing up, a three-wavelength fluorescent lamp installed at a position 1 m away was lit. The surface of the sample was observed from a direction that was 20° with respect to the vertical line dropped from the three-wavelength fluorescent lamp to the coated surface of the black board-bonded sample, and the anti-reflection property was evaluated according to the following criteria. If the evaluation was ○ or higher, it was determined that the anti-reflection property (anti-glare property) was good. ◎: No reflection is confirmed at all, or only a very slight reflection is confirmed. 〇: A slight reflection is confirmed. ×: A clear reflection is confirmed.

[0085] Table 4 shows the evaluation results.

[0086]

Table 4

[0087] As shown in Table 1, in all of the antiglare films according to Examples 1 to 6, the number of convex portions having a height of Sa or more from the average plane satisfied the above condition (A). Further, in all of the antiglare films according to Examples 1 to 6, the cross-sectional area of the convex portions cut by a plane parallel to the average plane and having a height of Sa from the average plane was 150 μm 2 less than, and the number of convex portions satisfied the above condition (B). All of the antiglare films according to Examples 1 to 6 had good antiglare property (reflection prevention property) and anti-glitter property at a fineness of 210 ppi or more. From this, it was confirmed that by satisfying the above condition (A) or (B), it was possible to realize an antiglare film capable of achieving both antiglare property and anti-glitter property even when used in a high-definition image display device with a fineness of 210 ppi or more.

[0088] The optical film according to Comparative Example 1 is a clear hard coat film provided with a hard coat layer that does not contain fine particles. Therefore, the surface smoothness is high, and the number of convex portions satisfying the above conditions (A) and (B) is extremely small. The optical film according to Comparative Example 1 has a smooth surface and does not produce a lens effect like an antiglare layer. Therefore, the transmitted image sharpness is high and the anti-glitter property is excellent. However, since the uneven shape for scattering incident light on the outermost surface is not sufficiently formed, the antiglare property (reflection prevention property) is insufficient.

[0089] The optical film according to Comparative Example 2 does not contain an organic filler but has a hard coat layer containing an organosilica sol. Since the hard coat layer contains a large amount of organosilica sol, surface irregularities are formed, but the above conditions (A) and (B) are not satisfied. The optical film according to Comparative Example 2 does not contain an organic filler and does not produce a lens effect like an antiglare layer. Therefore, the transmitted image sharpness is high and the anti-glitter property is excellent. However, since the uneven shape for scattering incident light on the outermost surface is not sufficiently formed, the antiglare property (reflection prevention property) is insufficient.

[0090] The antiglare films according to Comparative Examples 3 and 4 both had sufficient antiglare properties (reflection prevention properties), but their surface uneven shapes did not satisfy the above conditions (A) and (B). This is presumably because the small amount of organic filler added resulted in a small number of convex portions formed on the surface of the antiglare layer. Therefore, the anti-glitter property was insufficient, and it was not suitable for use as an antireflection film for high-definition image display devices with 210 ppi or more.

[0091] The antiglare films according to Comparative Examples 5 and 6 both had high antiglare properties (reflection prevention properties), but their surface uneven shapes did not satisfy the above conditions (A) and (B). This is presumably because the small number of organic fillers (when the addition amounts are the same, the larger the particle size of the organic filler, the smaller the number of particles) resulted in a small number of convex portions formed on the surface of the antiglare layer. Also, in Comparative Examples 5 and 6, it is considered that the number of convex portions formed decreased because the increased number of organic fillers sinking due to the thick film thickness of the antiglare layer. Therefore, the anti-glitter property was insufficient, and it was not suitable for use as an antireflection film for high-definition image display devices with 210 ppi or more.

Industrial Applicability

[0092] The present invention can be used as an antiglare film provided on the outermost surface of an image display device.

Explanation of Symbols

[0093] 1 Antiglare film 2 Transparent substrate 3 Antiglare layer 4 Low refractive index layer

Claims

Claim 1 An antiglare film having at least one antiglare layer laminated on a transparent substrate and having an uneven shape on the outermost surface, wherein the number of protrusions having an arithmetic mean height Sa or more present on the outermost surface, measured by an optical interference method, is 600 or more per measurement area. The antiglare film is characterized by this. Claim 2 An antiglare film having at least one antiglare layer laminated on a transparent substrate and having an uneven shape on the outermost surface, When the convex portion is cut by a plane parallel to the average plane of the concavo-convex shape and having a height from the average plane equal to the arithmetic mean height Sa, the number of convex portions having a cross-sectional area of less than 150 μm ２ is 480 or more per measurement area, and the antiglare film is characterized by this. Claim 3 The antiglare film according to claim 1 or 2, characterized in that the transmission image sharpness measured using a 0.5 mm optical brush is 92% or less. Claim 4 The antiglare film according to claim 1 or 2, characterized in that no glare is visually recognized when observing a light source in a state of being overlapped on a black matrix having a fineness of 210 ppi or more. Claim 5 The antiglare film according to claim 1 or 2, having a low refractive index layer on the antiglare layer. Claim 6 A display device comprising the antiglare film according to claim 1 or 2.

Images