JP2009186759A - Optical film, polarizing plate, and image display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical film which is superior in anti-glare, black color solidness, hardness, curling-proof, and brittleness, and which is low in average refractivity, and to provide a polarizing plate and image display that uses the optical film. <P>SOLUTION: This optical film has an ant-glare layer, containing a resin obtained by curing a reactive polymer which has a maleimide group in the side chain and no alkali soluble group and particles of 3-15 μm in average size, on a transparent base. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical film, a polarizing plate, and an image display device.

  In various image display devices such as liquid crystal display (LCD), plasma display panel (PDP), electroluminescence display (ELD), and cathode ray tube display (CRT), contrast reduction due to reflection of external light and image reflection In order to prevent this, an antiglare film or an antiglare antireflection film is used on the surface of the display. These display devices are widely used in offices and home environments, and an improvement in anti-glare property is required to prevent indoor fluorescent lamps and viewer images from being reflected on the display surface.

  The antiglare property can be achieved by providing irregularities on the surface of the film. On the other hand, if the surface irregularities are increased to provide antiglare properties, the film becomes whitish and so-called black tightening is deteriorated. In recent years, liquid crystal displays have become the mainstream of television, and this blackening has become more demanding. Therefore, both the antiglare property and the black tightening are important performances required for the antiglare film.

  As a method for imparting antiglare properties, a method is known in which fillers such as silica particles and resin particles are added to the resin to form surface irregularities (see, for example, Patent Documents 1 and 2). In this case, a method is generally used in which particles having a particle diameter smaller than the thickness of the film are used to aggregate the particles in the resin to form surface irregularities.

  The aggregation state of the particles can be controlled by changing the type of resin, the composition of the particles, the drying time when forming the coating film, and the like. Of these, polyfunctional acrylates have been mainly used for resins. However, with dipentaerystol hexaacrylate (DPHA) and pentaerythritol tetraacrylate (PETA) that have been used so far, increasing the anti-glare property causes a large deterioration in black tightening, making it difficult to achieve both anti-glare properties and black tightening. Met.

  On the other hand, since antiglare films and antiglare antireflection films are used on the surface of displays, high hardness is required. (Meth) acrylate-based resins such as DPHA and PETA that have been used so far can obtain high hardness, but it becomes difficult to handle curled surface films in manufacturing and processing, and cracks occur during handling. May occur or a peeling phenomenon may occur after bonding. In order to improve this, modified acrylate compounds (for example, see Patent Document 3), urethane acrylate compounds (for example, see Patent Document 4), acrylate compounds having different properties (for example, see Patent Documents 5 and 6), etc. An invention that uses is disclosed.

  In the above invention, although the curl improving effect and the brittleness are improved, the film surface hardness is lowered, and it is difficult to achieve both the surface hardness and these properties.

On the other hand, an invention relating to a lithographic printing plate in which a compound having maleimide in the side chain is used is disclosed (for example, see Patent Document 7). However, this invention makes no mention of optical film applications. Further, the compound used in the present invention has an alkali-soluble group and is not suitable for a surface film of a display which requires saponification resistance. Further, when the antiglare property is enhanced, the black tightening is greatly deteriorated, and it is difficult to achieve both the antiglare property and the black tightening.
JP-A-6-18706 Japanese Patent Laid-Open No. 10-20103 JP 2005-181996 A JP 2005-288787 A JP 2005-103979 A JP 2003-335983 A JP 7-295212 A

  An object of the present invention is to provide an optical film which is excellent in antiglare property, black tightening, hardness, curl and brittleness and has a low average reflectance. Furthermore, the objective of this invention is providing the polarizing plate and image display apparatus which comprised this optical film.

That is, the present inventors have achieved the above object with the following configurations.
As a result of intensive studies, the present inventors have developed an antiglare property by using an optical film that uses a resin having a maleimide group and a cured reactive polymer having no alkali-soluble group and particles having a specific particle size, The inventors have found that black tightening, hardness, curl and brittleness are excellent, and that a low average reflectance can be achieved, and the present invention has been completed.

[1] On a transparent support, a resin having a maleimide group in the side chain and a cured cured reactive polymer having no alkali-soluble group and an antiglare layer containing particles having an average particle diameter of 3 to 15 μm Optical film.
[2] The optical film according to [1], wherein the reactive polymer further has an ethylenically unsaturated group.
[3] The optical film according to [1] or [2], wherein the antiglare layer further contains a resin obtained by curing a reactive compound having a (meth) acrylate group.
[4] The optical film according to any one of [1] to [3], further including a layer having a lower refractive index than the antiglare layer.
[5] The optical film according to any one of [1] to [4], wherein the integrated reflectance is 3.0% or less.
[6] A polarizing plate having a polarizing film and two protective films protecting both surfaces of the polarizing film, wherein at least one of the protective films is an optical device according to any one of [1] to [5] A polarizing plate that is a film.
[7] An image display device having the optical film according to any one of [1] to [5] or the polarizing plate according to [6].

  In the present invention, surface irregularities are brought about by agglomerating particles having a particle diameter smaller than the film thickness, and antiglare property is imparted. Generally, the better the antiglare property, the more the film becomes whitish and the black tightening worsens. However, in the present invention, by adjusting the type and particle size of the binder resin, the shape of the surface unevenness is controlled, and both antiglare and black tightening are achieved, and furthermore, the hardness, curl and brittleness are excellent, and the average reflectance is high. A low optical film, a polarizing plate, and an image display device can be provided.

  Hereinafter, the present invention will be described in detail. In the present specification, when a numerical value represents a physical property value, a characteristic value, etc., the description “(numerical value 1) to (numerical value 2)” means “(numerical value 1) or more and (numerical value 2) or less”. . In the present specification, the description “(meth) acrylate” means “at least one of acrylate and methacrylate”. The same applies to “(meth) acrylic acid” and the like.

  Next, the components in the optical film of the present invention will be described. The optical film of the present invention includes a resin obtained by curing a reactive polymer having a maleimide group in the side chain and not having an alkali-soluble group as a binder component in the antiglare layer. The reactive polymer is preferably obtained by copolymerizing a monomer having a maleimide group and another monomer having no alkali-soluble group. Examples of the monomer having a maleimide group include monomers having a maleimide group represented by the following general formula (I).

In formula (I), R ¹ and R ² each represent a hydrogen atom, a halogen atom or an alkyl group, or R ¹ and R ² may be combined to form a 5-membered or 6-membered ring.

When R ¹ and / or R ^{2 in the} general formula (I) is an alkyl group, those having 1 to 4 carbon atoms are preferred, and a methyl group is particularly preferred. It is also preferred that R ¹ and R ² together form a 6-membered ring. As the halogen atom, a chlorine atom, a bromine atom or an iodine atom is preferable. Specific examples of the monomer having a maleimide group represented by the general formula (I) include monomers represented by the following general formula (A), (B) or (C).

In the formulas (A) to (C), R ¹¹ and R ¹² have the same meaning as R ¹ and R ^{2 in} the general formula (I), and R ¹³ is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms (for example, N3, n4 and n5 each represents an integer, preferably 1 to 6.

A monomer copolymerized with a monomer having a maleimide group does not have an alkali-soluble group. Thereby, saponification resistance can be imparted. Furthermore, control of particle aggregation that provides anti-glare properties becomes easy and the aggregation properties become uniform, so that both anti-glare properties and black tightening can be achieved. Examples of the alkali-soluble group include a carboxyl group, a phosphoric acid group, and a phosphonic acid group. Therefore, these monomers having no group are used as monomers for copolymerization.
As the monomer copolymerized with the monomer having a maleimide group, a vinyl monomer is preferable. By using an alkyl methacrylate or alkyl acrylate whose homopolymer has a glass transition point of room temperature or lower as the vinyl monomer, flexibility can be imparted to the copolymer.
It is also possible to further improve the crosslinking density by copolymerizing a monomer having an allyl group in the side chain, such as allyl methacrylate. Among them, copolymerization with vinyl monomers having a (meth) acryloyl group such as vinyl acrylate, vinyl methacrylate, 2-phenyl vinyl acrylate, 2-phenyl vinyl methacrylate, 1-propenyl acrylate, 1-propenyl methacrylate, etc. improves the crosslinking density. Preferred for.

  The copolymerization ratio of the monomer having a maleimide group and other monomers is preferably 20/80 to 80/20 (molar ratio), more preferably 30/70 to 70/30 (molar ratio). The weight average molecular weight of the copolymer having a maleimide group is preferably from 1,000 to 1,000,000, more preferably from 5,000 to 300,000. Two or more types of monomers having a maleimide group and other copolymerizable monomers may be used.

  In the present invention, a compound having another reactive group may be used as the binder component together with the reactive polymer having a maleimide group in the side chain. Among them, it is possible to suitably use an acrylate-based compound that has three or more (meth) acryloyl groups in one molecule and forms a hardened cured material widely used in the industry.

  Examples of the acrylate compound include esters of polyhydric alcohol and (meth) acrylic acid {for example, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO-modified tri Methylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, EO-modified tri (meth) acrylate phosphate, trimethylolethane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol Tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) Acrylate, 1,2,3-cyclohexane tetramethacrylate, polyurethane polyacrylate, polyester polyacrylate and caprolactone-modified tris (acryloyloxyethyl) isocyanurate.

  As specific compounds of polyfunctional acrylate compounds having three or more (meth) acryloyl groups, KAYARAD DPHA, DPHA-2C, PET-30, TMPTA, and TPA-320 manufactured by Nippon Kayaku Co., Ltd. , TPA-330, RP-1040, T-1420, D-310, DPCA-20, DPCA-30, DPCA-60, GPO-303, V made by Osaka Organic Chemical Industry Co., Ltd. An esterified product of a polyol such as # 400, V # 36095D and (meth) acrylic acid can be used. Also, purple light UV-1400B, UV-1700B, UV-6300B, UV-7550B, UV-7600B, UV-7605B, UV-7610B, UV-7620EA, UV-7630B, UV-7630B, UV-7640B. UV-6630B, UV-7000B, UV-7510B, UV-7461TE, UV-3000B, UV-3200B, UV-3210EA, UV-3210EA, UV-3310EA, UV-3310B, UV-3500BA , UV-3520TL, UV-3700B, UV-6100B, UV-6640B, UV-2000B, UV-2010B, UV-2250EA, UV-2750B (manufactured by Nippon Synthetic Chemical Co., Ltd.), UL-503LN (manufactured by Kyoeisha Chemical Co., Ltd.), Unidic 17-80 17-813, V-4030, V-4000BA (Dainippon Ink Chemical Co., Ltd.), EB-1290K, EB-220, EB-5129, EB-1830, EB-4358 (Daicel UCB ( Ltd.), High Corp AU-2010, AU-2020 (manufactured by Tokushi Co., Ltd.), Aronix M-1960 (manufactured by Toagosei Co., Ltd.), Art Resin UN-3320HA, UN-3320HC, UN-3320HS, UN Trifunctional urethane acrylate compounds such as -904, HDP-4T, Aronix M-8100, M-8030, M-9050 (manufactured by Toagosei Co., Ltd., KBM-8307 (manufactured by Daicel Cytec Co., Ltd.)) The above polyester compounds and the like can also be suitably used.

  Furthermore, resins having three or more (meth) acryloyl groups, such as relatively low molecular weight polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins And oligomers or prepolymers such as polyfunctional compounds such as polyhydric alcohols.

  When other monomers (trifunctional or higher polyfunctional (meth) acrylate compounds, etc.) are used in combination, the content of the other monomers is preferably 10 to 70% by mass, and 20 to 50% by mass with respect to the total amount of the binder. Further preferred.

  The optical film of the present invention contains particles having an average particle diameter of 3 to 15 μm. The desired particle size of the particles greatly depends on the antiglare property. When the film thickness of the antiglare layer is the same, generally the antiglare property decreases as the particle size decreases. When the particle diameter is increased, the antiglare property is increased, but the whole becomes whitish and so-called black tightening is deteriorated. The average particle size of the particles of the present invention is preferably 6 to 14 μm, more preferably 8 to 12 μm.

  Resin particles and / or inorganic fine particles are used for the particles of the present invention. Specific examples of the resin particles include, for example, crosslinked polymethyl methacrylate particles, crosslinked methyl methacrylate-styrene copolymer particles, crosslinked polystyrene particles, crosslinked methyl methacrylate-methyl acrylate copolymer particles, crosslinked acrylate-styrene copolymer particles, Preferred examples include resin particles such as melamine / formaldehyde resin particles and benzoguanamine / formaldehyde resin particles. Of these, crosslinked styrene particles, crosslinked polymethyl methacrylate particles, crosslinked methyl methacrylate-styrene copolymer particles, and the like are preferable. Furthermore, the surface of these resin particles is a so-called surface-modified particle in which a compound containing a fluorine atom, a silicon atom, a carboxyl group, a hydroxyl group, an amino group, an sulfonic acid group, a phosphoric acid group or the like is chemically bonded, or a nano particle such as silica or zirconia. The particle | grains which couple | bonded the inorganic fine particle of the size to the surface are also mentioned preferably.

  Inorganic fine particles can also be used. Specific examples of the inorganic fine particles include silica particles and alumina particles, and silica particles are particularly preferably used. However, resin particles are particularly preferably used in the present invention.

  From the viewpoint of making coating unevenness and interference unevenness conspicuous, or from the viewpoint of cost, the particles of the present invention are particularly preferably crosslinked polymethyl methacrylate particles and crosslinked methyl methacrylate-styrene copolymer particles. More preferably, crosslinked methyl methacrylate-styrene copolymer particles are used.

  As the shape of the particle, either a true sphere or an irregular shape can be used. The particle size distribution is preferably monodisperse particles because of the haze value, controllability of diffusibility, and uniformity of the coated surface. For example, when particles having a particle size of 20% or more than the average particle size are coarse particles, the proportion of the coarse particles is preferably 1% or less, more preferably 0.1% or less of the total number of particles. More preferably, it is 0.01% or less. If the number of coarse particles is too large, the surface roughness is not preferable. Particles having such a particle size distribution are obtained by classification after a normal synthesis reaction, and particles having a more preferable distribution can be obtained by increasing the number of classifications or increasing the degree of classification.

  The particle size distribution of the particles is measured by a Coulter counter method, and the measured distribution is converted into a particle number distribution. The average particle size is calculated from the obtained particle distribution.

  4-30 mass% in the total solid of a curable composition is preferable, as for the addition amount of the particle | grains of this invention, it is still more preferable that it is 6-25 mass%, Most preferably, it is 8-20 mass%. A plurality of particles having different particle diameters may be used.

  In the optical film of the present invention, in addition to the above-mentioned particles that provide antiglare properties, for the purpose of adjusting the refractive index, adjusting the film strength, reducing the shrinkage of curing, and reducing the reflectance when a low refractive index layer is provided Inorganic fillers can also be used. For example, it is made of an oxide containing at least one metal element selected from titanium, zirconium, aluminum, indium, zinc, tin, and antimony, and the average particle size of primary particles is generally 0.2 μm or less, preferably It is also preferable to contain a fine high refractive index inorganic filler that is 0.1 μm or less, more preferably 0.06 μm or less and 1 nm or more.

  Conversely, when it is necessary to lower the refractive index of the matrix, a fine low refractive index inorganic filler such as silica fine particles or hollow silica fine particles can be used as the inorganic filler. The preferred particle size is the same as that of the fine high refractive index inorganic filler.

  The surface of the inorganic filler is also preferably subjected to silane coupling treatment or titanium coupling treatment, and a surface treatment agent having a functional group capable of reacting with the binder species on the filler surface is preferably used.

  The addition amount of these fine inorganic fillers is preferably 5 to 90% by mass, more preferably 10 to 80% by mass, and particularly preferably 20 to 75% by mass with respect to the total mass of the antiglare layer.

  The fine inorganic filler does not scatter because the particle size is sufficiently shorter than the wavelength of light, and the dispersion in which the filler is dispersed in the binder polymer has the property of an optically uniform substance.

  The curable composition for forming the optical film of the present invention is cured with a photopolymerization initiator. The photopolymerization initiator of the present invention is a compound that generates radicals capable of initiating radical polymerization reaction by irradiation with ionizing radiation, and is referred to as “Latest UV Curing Technology” (p.159, publisher; Kazuhiro Takasawa, publisher; Technical Information Association, Inc., published in 1991), Ciba Specialty Chemicals Co., Ltd., JP 2001-139663, JP 5-83588, JP 5-83588, JP 1-304453. U.S. Pat. No. 3,479,185, JP-A-5-239015, JP-A-8-134404, JP-A-11-217518, JP-A-2002-116539, JP-A-2002-116539, etc. Various known photopolymerization initiators described can be used. Among them, a photoinitiator having a photosensitivity wavelength of 300 nm to 430 nm and having a high photoinitiating ability is preferably used because the photosensitivity wavelength is matched with a light source such as a high-pressure mercury lamp or a metal halide lamp and exhibits high sensitivity. From the viewpoint of coloring the film, those having a photosensitive wavelength of 300 nm to 380 nm are more preferable.

  These polymerization initiators are preferably used in correspondence with the compounds to be polymerized, and are preferably used in a range of 0.1 to 15 parts by mass in terms of the total amount of the polymerization initiator with respect to 100 parts by mass of the compound to be polymerized. The range of 1-10 mass parts is more preferable.

  Specific photopolymerization initiators are listed below, but are not limited thereto.

  Among the above compounds, the trihalomethyl-s-triazine initiators described in C-1 to C-6, the acylphosphone initiators described in C-13, C-14, C-16, and C-17, The C-18, C-23, C-22, and C-29 α-cleavage initiators, and the C-26 and C-28 ketoxime initiators are preferred because of high sensitivity and less coloring.

  The optical film of the present invention may contain a polymer compound. By adding the polymer compound, the viscosity of the coating liquid for forming the optical film can be adjusted, and the curing shrinkage of the optical film can be reduced.

  The polymer compound has already formed a polymer when added to the coating solution. Examples of the polymer compound include cellulose esters (for example, cellulose triacetate, cellulose diacetate, cellulose propionate, cellulose acetate Pionate, cellulose acetate butyrate, cellulose nitrate, etc.), urethane acrylates, polyester acrylates, (meth) acrylic acid esters (for example, methyl methacrylate / (meth) methyl acrylate copolymer, methyl methacrylate / (Meth) ethyl acrylate copolymer, methyl methacrylate / (meth) butyl acrylate copolymer, methyl methacrylate / styrene copolymer, methyl methacrylate / (meth) acrylic acid copolymer, polymethyl methacrylate Etc.), poly Resins such as styrene are preferably used.

  The polymer compound is preferably 1 to 50% by mass, more preferably 5 to 5% by mass, based on the total binder contained in the layer containing the polymer compound, from the viewpoint of the viscosity increasing effect and the effect on curing shrinkage in the optical film. It is preferable to contain in 40 mass%. Further, the molecular weight of the polymer compound is preferably from 30,000 to 400,000 in terms of mass average, more preferably from 50,000 to 300,000, and even more preferably from 50,000 to 200,000.

  In the coating liquid for producing the optical film of the present invention, in order to ensure surface uniformity such as coating unevenness, drying unevenness, point defects, etc., either a fluorine-based surfactant or a silicone-based surfactant, or both It is preferable to contain. In particular, a fluorine-based surfactant is preferably used because an effect of improving surface defects such as coating unevenness, drying unevenness, and point defects of the optical film of the present invention appears with a smaller addition amount.

  Preferable examples of the fluorosurfactant include compounds described in paragraph numbers 0049 to 0074 of JP 2007-188070 A, for example.

  A preferable addition amount of a surfactant (fluorine polymer or the like) used in the coating solution for producing the optical film of the present invention is in the range of 0.001 to 5% by mass, preferably 0.005 with respect to the coating solution. It is the range of -3 mass%, More preferably, it is the range of 0.01-1 mass%. When the addition amount of the fluorine-based polymer is 0.001% by mass or more, the effect is sufficient, and by setting it to 5% by mass or less, the coating film is sufficiently dried and good performance as a coating film (for example, reflection) Rate, scratch resistance).

  An organic solvent can be added to the coating solution for producing the optical film of the present invention. As an organic solvent, for example, in an alcohol system, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, isoamyl alcohol, 1-pentanol, n-hexanol, methyl amyl alcohol In the ketone system, methyl isobutyl ketone, methyl ethyl ketone, diethyl ketone, acetone, cyclohexanone, diacetone alcohol, etc., in the ester system, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, isobutyl acetate, n-butyl acetate, Isoamyl acetate, n-amyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl acetate, methyl lactate, ethyl lactate, etc. In ether and acetal systems, 1,4 dioxane Tetrahydrofuran, 2-methylfuran, tetrahydropyran, diethyl acetal, etc., hydrocarbon type, hexane, heptane, octane, isooctane, ligroin, cyclohexane, methylcyclohexane, toluene, xylene, ethylbenzene, styrene, divinylbenzene, etc., halogen hydrocarbon type In, carbon tetrachloride, chloroform, methylene chloride, ethylene chloride, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, tetrachloroethylene, 1,1,1,2-tetrachloroethane In the polyhydric alcohol and its derivative system, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoacetate, diethylene glycol, Lopylene glycol, dipropylene glycol, butanediol, hexylene glycol, 1,5-pentanediol, glycerin monoacetate, glycerin ethers, 1,2,6-hexanetriol, etc. In fatty acid systems, formic acid, acetic acid, propionic acid, In the case of nitrogen compounds such as entrained acid, isoentangled acid, isovaleric acid, and lactic acid, formamide, N, N-dimethylformamide, acetamide, acetonitrile, and the like, and in the case of sulfur compounds, dimethyl sulfoxide and the like can be mentioned.

  Among organic solvents, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, acetone, toluene, xylene, ethyl acetate, 1-pentanol and the like are particularly preferable. For the purpose of controlling cohesion, an alcohol or a polyhydric alcohol solvent is appropriately mixed. May be used.

  These organic solvents may be used alone or in combination. The total amount of the organic solvent in the curable composition is preferably 20% by mass to 90% by mass, and preferably 30% by mass to 80% by mass. Is more preferable, and it is most preferable to contain 40 mass%-70 mass%. In order to stabilize the surface shape of the antiglare layer, it is preferable to use a solvent having a boiling point of less than 100 ° C. and a solvent having a boiling point of 100 ° C. or more in combination.

  The coating liquid for producing the optical film of the present invention is applied on a transparent substrate to form an optical film having an antiglare layer. The antiglare layer is preferably formed by applying a curable composition of the present invention on a transparent substrate, and then carrying out light irradiation, electron beam irradiation, heat treatment, etc., and crosslinking or polymerization reaction. In the case of ultraviolet irradiation, ultraviolet rays emitted from light such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, etc. can be used. Curing with ultraviolet rays is preferably carried out by nitrogen purge or the like in an atmosphere having an oxygen concentration of 4% by volume or less, more preferably 2% by volume or less, and most preferably 0.5% by volume or less.

  In the optical film of the present invention, an antiglare layer is formed by applying a coating solution for forming an optical film on a transparent support. The antiglare layer of the optical film of the present invention may be a single layer or may be composed of a plurality of layers (2 to 4 layers).

The example of the preferable layer structure of the optical film of this invention is shown below. In the following configuration, the base film refers to a support composed of a film.
・ Base film / antiglare layer ・ Base film / antistatic layer / antiglare layer ・ Base film / antiglare layer / low refractive index layer ・ Base film / antiglare layer / antistatic layer / low refractive index layer -Base film / hard coat layer / antiglare layer / low refractive index layer- Base film / hard coat layer / anti-glare layer / antistatic layer / low refractive index layer-Base film / hard coat layer / antistatic layer / Anti-glare layer / Low refractive index layer -Base film / Anti-glare layer / High refractive index layer / Low refractive index layer -Base film / Anti-glare layer / Medium refractive index layer / High refractive index layer / Low refractive index layer・ Antistatic layer / Base film / Anti-glare layer / Medium refractive index layer / High refractive index layer / Low refractive index layer ・ Base film / Antistatic layer / Anti-glare layer / Medium refractive index layer / High refractive index layer / Low refractive index layer Antistatic layer / base film / antiglare layer / high refractive index layer / low refractive index layer / high refractive index layer / low refractive index layer

  In the optical film of the present invention, layers other than the antiglare layer may be coated, and examples of these layers include a hard coat layer, an antistatic layer, a low refractive index layer, and an antifouling layer. . More preferably, the antiglare layer has functions such as a hard coat layer, an antistatic layer, and an antifouling layer at the same time.

  In the present invention, an antireflection film comprising a medium refractive index layer / a high refractive index layer / a low refractive index layer is preferable from the viewpoint of low reflection. For example, JP-A-8-122504 and 8-110401 are preferable. The configurations described in Japanese Patent Laid-Open No. 10-300902, Japanese Patent Laid-Open No. 2002-243906, Japanese Patent Laid-Open No. 2000-11706, and the like can be given. In terms of simple production and high productivity, the most preferred embodiment of the present invention is an optical film having a single antiglare layer on a support, and a single antiglare layer and a single layer on a support. It is an antireflection film which has the low refractive index layer of this order.

  The thickness of the antiglare layer of the optical film of the present invention is preferably 5 μm to 30 μm, preferably 8 μm to 25 μm, and most preferably 10 μm to 20 μm. When the particle size is less than 5 μm, the surface irregularity becomes too large when the particles as the constituent of the present invention are used, and the black tightening deteriorates. When the particle size exceeds 30 μm, from the viewpoint of productivity, curling, brittleness, and thinning of the display. It is not preferable. The thickness / particle size ratio, which is the ratio between the thickness of the antiglare layer and the average particle diameter of the particles, is preferably 0.9 to 3.0, more preferably 1.2 to 2.5. When the thickness / particle size ratio is 0.9 or more, the surface unevenness is an appropriate size and black tightening is improved, and when it is 3.0 or less, a desired antiglare effect can be sufficiently obtained.

  In order to reduce the reflectance of the film of the present invention, it is preferable to use a low refractive index layer. The refractive index of the low refractive index layer is preferably 1.20 to 1.46, more preferably 1.25 to 1.46, and particularly preferably 1.30 to 1.40.

  The thickness of the low refractive index layer is preferably 50 to 200 nm, and more preferably 70 to 100 nm. The haze of the low refractive index layer is preferably 3% or less, more preferably 2% or less, and most preferably 1% or less.

As a preferable curable composition for forming the low refractive index layer,
(1) A composition containing a fluorine-containing polymer having a crosslinkable or polymerizable functional group,
(2) a composition comprising as a main component a hydrolysis-condensation product of a fluorine-containing organosilane material;
(3) a composition containing a monomer having two or more ethylenically unsaturated groups and inorganic fine particles having a hollow structure;
Is mentioned.

(1) Fluorine-containing compound having a crosslinkable or polymerizable functional group As the fluorine-containing compound having a crosslinkable or polymerizable functional group, co-polymerization of a fluorine-containing monomer and a monomer having a crosslinkable or polymerizable functional group Coalescence can be mentioned. Specific examples of these fluoropolymers are described in JP2003-222702A, JP2003-183322A, and the like.

As described in JP 2000-17028 A, a curing agent having a polymerizable unsaturated group may be used in combination with the above polymer. Moreover, combined use with the compound which has a fluorine-containing polyfunctional polymerizable unsaturated group as described in Unexamined-Japanese-Patent No. 2002-145952 is also preferable. Examples of the compound having a polyfunctional polymerizable unsaturated group include the above-described monomers having two or more ethylenically unsaturated groups. Moreover, the hydrolysis-condensation product of the organolane described in Unexamined-Japanese-Patent No. 2004-170901 is also preferable, and the hydrolysis-condensation product of the organosilane containing a (meth) acryloyl group is especially preferable.
These compounds are particularly preferred because they have a large combined effect for improving scratch resistance, particularly when a compound having a polymerizable unsaturated group is used in the polymer body.

  When the polymer itself does not have sufficient curability, necessary curability can be imparted by blending a crosslinkable compound. For example, when the polymer main body contains a hydroxyl group, various amino compounds are preferably used as the curing agent. The amino compound used as the crosslinkable compound is, for example, a compound containing one or both of a hydroxyalkylamino group and an alkoxyalkylamino group in total, specifically, for example, a melamine compound, Examples include urea compounds, benzoguanamine compounds, glycoluril compounds, and the like. For curing these compounds, an organic acid or a salt thereof is preferably used.

(2) Hydrolyzed condensate of fluorine-containing organosilane material A composition containing a hydrolyzed condensate of a fluorine-containing organosilane compound as a main component is also preferable because of its low refractive index and high hardness on the coating film surface. A condensate of a tetraalkoxysilane with a hydrolyzable silanol-containing compound at one or both ends with respect to the fluorinated alkyl group is preferred. The specific composition is described in Unexamined-Japanese-Patent No. 2002-265866, 317152.

(3) A composition containing a monomer having two or more ethylenically unsaturated groups and inorganic fine particles having a hollow structure As yet another preferred embodiment, a low refractive index layer comprising low refractive index particles and a binder can be mentioned. . The low refractive index particles may be organic or inorganic, but particles having pores inside are preferable. Specific examples of the hollow particles are described in the silica-based particles described in JP-A-2002-79616. The particle refractive index is preferably 1.15 to 1.40, more preferably 1.20 to 1.30. Examples of the binder include monomers having two or more ethylenically unsaturated groups described on the page of the antiglare layer.

  It is preferable to add the polymerization initiator described on the page of the antiglare layer to the low refractive index layer of the present invention. When a radically polymerizable compound is contained, 1 to 10 parts by mass, preferably 1 to 5 parts by mass of a polymerization initiator can be used with respect to the compound.

  In the low refractive index layer of the present invention, inorganic particles can be used in combination. In order to impart scratch resistance, fine particles having a particle size of 15% to 150%, preferably 30% to 100%, more preferably 45% to 60% of the thickness of the low refractive index layer can be used. .

  In the low refractive index layer of the present invention, for the purpose of imparting properties such as antifouling property, water resistance, chemical resistance, and slipping property, a known polysiloxane-based or fluorine-based antifouling agent, slipping agent, etc. are appropriately used. Can be added.

  In the present invention, the preferred integrated reflectance of the antireflection antiglare film provided with a low refractive index layer or the like is preferably 3.0% or less, more preferably 2.0% or less, and most preferably 1.5%. % Or less and 0.3% or more. By reducing the integrated reflectance, sufficient antiglare properties can be obtained even if the light scattering on the surface of the antiglare film is reduced, so that an antiglare antireflection film excellent in blackening can be obtained.

  A plastic film is preferably used as the transparent support of the optical film of the present invention. Examples of the polymer forming the plastic film include cellulose acylate (eg, triacetyl cellulose, diacetyl cellulose, typically TAC-TD80U, TD80UF, etc., manufactured by Fuji Film), polyamide, polycarbonate, polyester (eg, polyethylene terephthalate, polyethylene). Naphthalate), polystyrene, polyolefin, norbornene resin (Arton: trade name, manufactured by JSR), amorphous polyolefin (ZEONEX: trade name, manufactured by ZEON CORPORATION), (meth) acrylic resin (ACRYPET VRL20A: product) Name, manufactured by Mitsubishi Rayon Co., Ltd., ring structure-containing acrylic resin described in JP-A No. 2004-70296 and JP-A No. 2006-171464), and the like. Of these, triacetyl cellulose, polyethylene terephthalate, and polyethylene naphthalate are preferable, and triacetyl cellulose is particularly preferable.

  When the optical film of the present invention is used in a liquid crystal display device, it is disposed on the outermost surface of the display by providing an adhesive layer on one side. Moreover, you may combine the optical film and polarizing plate of this invention. When the transparent support is triacetyl cellulose, triacetyl cellulose is used as a protective film for protecting the polarizing layer of the polarizing plate. Therefore, it is preferable in terms of cost to use the optical film of the present invention as it is for the protective film.

  When the optical film of the present invention is disposed on the outermost surface of a display by providing an adhesive layer on one side or used as it is as a protective film for a polarizing plate, the optical film on the transparent support is sufficient for adhesion. It is preferable to carry out a saponification treatment after forming the outermost layer. The saponification treatment is performed by a known method, for example, by immersing the film in an alkali solution for an appropriate time. After being immersed in the alkaline solution, it is preferable to sufficiently wash with water or neutralize the alkaline component by dipping in a dilute acid so that the alkaline component does not remain in the film. By saponification treatment, the surface of the transparent support opposite to the side having the outermost layer is hydrophilized.

[Surface form]
In the optical film of the present invention, it is preferable to achieve both good antiglare property and black tightening. Regarding anti-glare properties, in practice, it is necessary to show good anti-glare properties when various light sources are reflected from various angles. As a result of the inventors' diligent efforts, it has been found that such reflections can be easily evaluated by changing the viewing angle when the light source is reflected. A large light source (for example, a fluorescent lamp) and a thin light source It is necessary to show good reflection in both of them (for example, a linear light source made by simulating a fluorescent lamp with a cover). As for black tightening, it is necessary to achieve good black tightening both when viewed from the vertical direction of the display in a bright room environment and when viewed at an angle of about 45 °. In order to achieve an excellent antiglare property and black tightening by evaluating with such an index, it has been found that it is necessary to achieve a specific surface form within the above-mentioned film thickness range. Preferred ranges such as the particle size and refractive index of the above particles are necessary requirements for achieving a specific surface morphology with the above film thickness. The preferable surface form (surface unevenness | corrugation) of the optical film of this invention is described below.

  In the light scattering film of the present invention, the center line average roughness Ra is preferably 0.05 to 0.25 μm, and more preferably 0.10 to 0.20 μm, as the surface uneven shape. If Ra is too large, black tightening and bright room contrast deteriorate, and if Ra is too small, antiglare property deteriorates. The 10-point average roughness Rz is particularly preferably 10 times or less of Ra.

  In order to obtain a surface form suitable for achieving both antiglare properties and black tightening, the average mountain valley distance Sm is also important. Sm is preferably 60 to 130 μm, more preferably 60 to 100 μm, and particularly preferably 70 to 90 μm. If Sm is too large, the surface becomes rough and the appearance is not good, and the reflection of a large-sized light source becomes easy to see. If Sm is too small, black tightening is deteriorated and edge blur of a thin light source (line light source) becomes weak, which is not preferable.

  In order to improve the bright room contrast, it is necessary to simultaneously control the average inclination angle to a specific range. The average inclination angle is preferably 0.5 to 3.0 degrees, more preferably 0.7 to 2.0 degrees. If the average inclination angle is too large, the black tightening is deteriorated, and the edge blur of a thin light source (line light source) is not preferable because the edge blur becomes weak. If the average inclination angle is too small, the reflection of a large-sized light source becomes easy to see, which is not preferable.

  In order to achieve the excellent antiglare property and black tightening of the object of the present invention, the maximum value (θp) of the inclination angle distribution is also very important. θp is preferably 0.05 ° to 0.50 °, more preferably 0.05 ° to 0.30 °. If θp is too small, the reflection of a light source having a large size is likely to be visible, and if it is too large, black tightening is deteriorated and edge blur of a thin light source (line light source) is weakened.

  The average inclination angle of the optical film of the present invention is determined by the following method. That is, a triangle formed by three points where the vertex of a triangle having an area of 0.5 to 2 square micrometers is assumed on the transparent film substrate surface, and three perpendiculars extending vertically upward from the point intersect the film surface. The angle between the normal of the surface and the perpendicular extending vertically upward from the support is defined as the inclination angle of the surface, and an area of 250,000 square micrometers (0.25 square millimeters) or more on the substrate is divided into the triangles. The average value of all the measurement points when measured in this manner is calculated as the average inclination angle.

  A method for measuring the tilt angle will be described in more detail. The film is divided into meshes having an area of 0.5 to 2 square micrometers as shown in FIG. FIG. 1B is a diagram in which three points of the divided mesh are extracted. A perpendicular line is extended vertically upward from three points on the support, and points where the three points intersect the surface are designated as A, B, and C. An angle θ formed by a normal line DD ′ of the triangle ABC plane and a perpendicular line OO ′ extending vertically upward from the support is defined as an inclination angle. FIG. 1C is a cross-sectional view of the film taken along a plane P including the point O′DD ′. A line segment EF is an intersection line between the triangle ABC and the plane P. The measurement area is preferably 250,000 square micrometers (0.25 square millimeters) or more on the support, and this surface is divided into triangles on the support and measured to determine the inclination angle. There are several devices to measure, but an example will be described. A case will be described in which an SXM520-AS150 model manufactured by Micromap (USA) is used as the apparatus. For example, when the objective lens is 10 times, the measurement unit of the tilt angle is 0.8 square micrometers, and the measurement range is 500,000 square micrometers (0.5 square millimeters). If the magnification of the objective lens is increased, the measurement unit and the measurement range are reduced accordingly. The measurement data can be analyzed using software such as MAT-LAB to calculate the inclination angle distribution, and the average inclination angle can be calculated based on the data.

〔optical properties〕
In the light scattering film of the present invention, haze due to surface scattering (hereinafter also referred to as surface haze) is preferably 0.2% to 10%, particularly preferably 0.2% to 5%. When the surface haze is too large, the black tightening is deteriorated, and when it is too small, the antiglare property is deteriorated.

  In the light scattering film of the present invention, haze caused by internal scattering (hereinafter also referred to as internal haze) is preferably 1% to 40%, more preferably 5% to 30%, and more preferably 10% to Particularly preferred is 25%. If the internal haze is too large, the front contrast is lowered and the brownishness is increased. If it is too small, combinations of materials that can be used are limited, and it is difficult to match anti-glare properties and other characteristic values, and there is a problem of high costs.

The surface haze and internal haze can be measured by the following procedure.
(1) The total haze value (H) of the film is measured according to JIS-K7136.
(2) A few drops of silicone oil are added to the front and back surfaces of the low refractive index region side of the film, and sandwiched from the front and back using two 1 mm thick glass plates (micro slide glass product number S 9111, manufactured by MATSANAMI), Two glass plates and a film are optically closely adhered to each other, the haze is measured with the surface haze removed, and only the silicone oil is sandwiched between two separately measured glass plates to subtract the measured haze. The calculated value is calculated as the internal haze (Hi) of the film.
(3) A value obtained by subtracting the internal haze (Hi) calculated in (2) from the total haze (H) measured in (1) above is calculated as the surface haze (Hs) of the film.

  The light scattering film of the present invention has an image clarity according to JIS K7105 of preferably 30% to 99%, more preferably 40% to 95%, and still more preferably 50 when measured at an optical comb width of 0.5 mm. % To 90%, more preferably 60% to 80%. When the image clarity is low, the bright room contrast is deteriorated, and when it is high, the antiglare property is deteriorated.

(Application method)
The optical film of the present invention can be formed by the following method, but is not limited to this method.
First, a coating solution containing components for forming each layer is prepared. Next, a coating solution for forming various functional layers is applied onto the transparent support by dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating or die coating. The microgravure coating method, the wire bar coating method, and the die coating method (see US Pat. No. 2,681,294 and JP-A-2006-122889) are more preferable, and the die coating method is particularly preferable.
Thereafter, the monomer for forming the functional layer is polymerized and cured by light irradiation or heating. Thereby, a functional layer is formed. If necessary, the functional layer can be a plurality of layers.
Next, a coating solution for forming a low refractive index layer is applied onto the functional layer in the same manner, and is irradiated with light or heated (irradiated with ionizing radiation such as ultraviolet rays, preferably irradiated with ionizing radiation under heating. Cured) to form a low refractive index layer. In this way, the optical film of the present invention is obtained.

  The polarizing plate is mainly composed of two protective films that protect both the front and back sides of the polarizing film. The optical film of the present invention is preferably used for at least one of the two protective films sandwiching the polarizing film from both sides. The manufacturing cost of a polarizing plate can be reduced because the optical film of the present invention also serves as a protective film. In addition, by using the optical film of the present invention as the outermost layer, reflection of external light and the like can be prevented, and a polarizing plate having excellent scratch resistance, antifouling property and the like can be obtained.

After the surface of the optical film of the present invention is hydrophilized, it is bonded to a polarizer using polyvinyl alcohol as an adhesive to form a polarizing plate. As the hydrophilization treatment, saponification treatment is particularly preferable. The hydrophilized surface is particularly effective for improving the adhesion with a polarizing film containing polyvinyl alcohol as a main component. In addition, the hydrophilic surface makes it difficult for dust in the air to adhere to it, making it difficult for dust to enter between the polarizing film and the optical film when bonded to the polarizing film, and is effective in preventing point defects caused by dust. It is.
The saponification treatment is preferably carried out so that the contact angle of water on the surface of the transparent support opposite to the side having the outermost layer is 40 ° or less. More preferably, it is 30 ° or less, particularly preferably 20 ° or less.

(Image display device)
The optical film of the present invention is applied to an image display device such as a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), a cathode ray tube display device (CRT), and a surface electric field display (SED). can do. It is particularly preferably used for a liquid crystal display (LCD). Since the optical film of the present invention has a transparent support, it is used by bonding the transparent support side to the image display surface of the image display device. Moreover, when using for a liquid crystal display device, after processing in the said polarizing plate form, it can provide and use so that the optical film of this invention may become the outermost surface on the surface of a liquid crystal cell.

  When the optical film of the present invention is used as one side of a surface protective film of a polarizing film, it is twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), optically. It can be preferably used for a transmissive, reflective, or transflective liquid crystal display device in a mode such as a compensated bend cell (OCB).

  In order to describe the present invention in detail, examples will be described below, but the present invention is not limited thereto. Unless otherwise specified, “part” and “%” are based on mass.

[Example 1]
(Preparation of coating solution A-1 for antiglare layer)
An antiglare layer coating solution A-1 which is a curable composition having the following composition was prepared.
N- [6- (methacryloyloxy) propyl] -2,3-dimethylmaleimide / methacrylic acid = 50/50 (molar ratio) copolymer (MW = 30000) 88.0 g
Irgacure 127 (IRG-127) 3.0 g
10 μm cross-linked acrylic-styrene particle dispersion (30%) 26.4 g
SP-13 0.2g
MIBK 22.0g
MEK 40.4g
The particle dispersion was prepared by gradually adding the particles to the stirring MIBK solution until the solid content concentration of the dispersion reached 40% by mass and stirring for 30 minutes. After the preparation, it was filtered through a polypropylene filter having a pore size of 30 μm to obtain a coating solution.

(Preparation of antiglare layer coating solutions A-2 to A-30)
Coating solutions A-2 to A-30 were prepared in the same manner as coating solution A-1, except that the coating solution composition was changed as shown in Table 1. “Amount” in Table 1 means mass% with respect to the total solid content in the coating solution.

Irgacure 127: Polymerization initiator {Ciba Specialty Chemicals Co., Ltd.}
10 μm crosslinked acrylic-styrene particles: refractive index n = 1.55 {manufactured by Sekisui Plastics Co., Ltd.}
SP-13: Fluorine-based surfactant having the following structure (used in MEK solvent at a solid concentration of 40% by mass)
PET-30: A mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate [manufactured by Nippon Kayaku Co., Ltd.]
DPHA: A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate [manufactured by Nippon Kayaku Co., Ltd.]
MIBK: Methyl isobutyl ketone MEK: Methyl ethyl ketone

(Preparation of coating solution L-1 for low refractive index layer)
A coating solution L-1 for a low refractive index layer having the following composition was prepared.
Ethylenically unsaturated group-containing fluorine-containing polymer (A-1) 3.9 g
The following silica dispersion A (22%) 25.0 g
Irgacure 127 0.2g
DPHA 0.4g
MEK 100.0g
MIBK 45.5g

DPHA: A mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate [manufactured by Nippon Kayaku Co., Ltd.]
Irgacure 127: Polymerization initiator [Ciba Specialty Chemicals Co., Ltd.]
Ethylenically unsaturated group-containing fluoropolymer (A-1): fluoropolymer (A-1) described in Production Example 3 of JP-A-2005-89536

(Silica dispersion A)
Hollow silica fine particle sol (isopropyl alcohol silica sol, average particle diameter 60 nm, shell thickness 10 nm, silica concentration 20 mass%, silica particle refractive index 1.31, prepared by changing the size according to Preparation Example 4 of JP-A-2002-79616 ) 10 g of acryloyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd.) and 1.0 g of diisopropoxyaluminum ethyl acetate were added to and mixed with 500 g, and then 3 g of ion-exchanged water was added. After making it react at 60 degreeC for 8 hours, it cooled to room temperature and added 1.0 g of acetylacetone. While adding cyclohexanone to 500 g of this dispersion so that the content of silica was almost constant, solvent substitution by vacuum distillation was performed. There was no generation of foreign matter in the dispersion, and the viscosity when the solid content concentration was adjusted to 22% by mass with cyclohexanone was 5 mPa · s at 25 ° C. When the residual amount of isopropyl alcohol in the obtained dispersion A was analyzed by gas chromatography, it was 1.0%.

(Preparation of optical film samples 101-136)
(Coating of antiglare layer)
A triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Film Co., Ltd.) having a thickness of 80 μm is unwound in a roll form, and an antiglare layer coating solution shown in Table 1 is used. The die coating method using the slot die described in Example 1 was applied under the conditions of a conveyance speed of 30 m / min, dried at 60 ° C. for 150 seconds, and further 160 W / cm at an oxygen concentration of about 0.1% under a nitrogen purge. Using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.), the coating layer was cured by being irradiated with ultraviolet rays having an illuminance of 400 mW / cm ² and an irradiation amount of 100 mJ / cm ² . The coating amount was adjusted so that the thickness / particle size ratio, which is the ratio of the average particle diameter of the particles, to the film thickness of each antiglare layer was the value shown in Table 2.

(Coating of low refractive index layer)
The triacetyl cellulose film coated with the antiglare layer was unwound again, and the coating solution for the low refractive index layer was applied by a die coating method using the slot die under the condition of a conveyance speed of 30 m / min. After drying at 75 ° C. for 75 seconds, using an air-cooled metal halide lamp (made by Eye Graphics Co., Ltd.) with an oxygen concentration of 0.01 to 0.1% under a nitrogen purge, an illuminance of 400 mW / cm ² and an irradiation amount An ultraviolet ray of 240 mJ / cm ² was irradiated to form a low refractive index layer having a thickness of 100 nm, and wound up to produce an antiglare antireflection film.

(Saponification of optical film)
After coating, the sample was subjected to the following treatment. A 1.5 mol / L aqueous sodium hydroxide solution was prepared and kept at 55 ° C. A 0.01 mol / L dilute sulfuric acid aqueous solution was prepared and kept at 35 ° C. The produced optical film was immersed in the aqueous sodium hydroxide solution for 2 minutes, and then immersed in water to sufficiently wash away the aqueous sodium hydroxide solution. Subsequently, after being immersed in the above-mentioned dilute sulfuric acid aqueous solution for 1 minute, it was immersed in water to sufficiently wash away the dilute sulfuric acid aqueous solution. Finally, the sample was thoroughly dried at 120 ° C. In this way, saponified optical film samples 101 to 136 were produced.

(Preparation of polarizing plate)
Iodine is adsorbed on polyvinyl alcohol and stretched on one side of a polarizer prepared by dipping in a 1.5 mol / L, 55 ° C. NaOH aqueous solution for 2 minutes, neutralized and washed with water, 80 μm thick triacetyl. Cellulose film (TAC-TD80U, manufactured by Fuji Film Co., Ltd.) was pasted, and each of the optical film samples (saponified) was pasted on the other side to protect both sides of the polarizer to produce a polarizing plate. .

(Evaluation of optical film and polarizing plate)
About these obtained optical film samples, the following items were evaluated. The results are shown in Table 2.

(1) Anti-glare property The entire back side of the coated surface of the obtained film is painted with black magic ink, and a bare fluorescent lamp (8000 cd / m ² ) without louver is projected from a 45 degree angle, from a -45 degree direction. The degree of blurring of the reflected image when observed was evaluated according to the following criteria.
◎: The outline of the fluorescent lamp is hardly understood. ○: The outline of the fluorescent lamp can be seen a little clearly. Δ: The outline of the fluorescent lamp can be seen relatively clearly.
X: The outline of the fluorescent light is clearly visible or dazzling.

(2) Black tightening For the liquid crystal display device in which a polarizing plate with an optical film attached to the surface on the viewing side was disposed, the black tightening was subjected to a sensory evaluation. The evaluation method is a method in which multiple displays are arranged in parallel and compared at the same time. From the front, the blackness when the power is turned off and the blackness (black image) when the power is turned on are compared for each film, and evaluated according to the following criteria. did. It was expressed by the standard that the stronger the blackness, the stronger the tightness of the screen. The evaluation was performed in two directions, a 5 ° direction and a 45 ° direction, with the direction perpendicular to the display surface being 0 ° in a bright room environment.
A: Strong black and the screen looks very strong.
○: Black color is strong and the screen looks strong.
Δ: Black but gray, and the screen is not tight.
×: The color is very gray and there is no tightness on the screen.

(3) Average reflectance The back side of the film was roughened with sandpaper, then treated with black ink, and the back side was removed, using the spectrophotometer (manufactured by JASCO Corporation). The spectral reflectance was measured in the wavelength region of 380 to 780 nm. The arithmetic average value of the integrated reflectance of 450 to 650 nm was used for the result.

(4) Pencil hardness Pencil hardness evaluation described in JIS K 5400 was performed as an index of scratch resistance. The antireflection film was conditioned at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, and then evaluated using the 4H test pencil specified in JIS S 6006 at a load of 1 kg according to the following criteria. A level of △ or higher was regarded as acceptable.
A: No scratch is observed in the evaluation of n = 5.
○: One flaw is recognized in the evaluation of n = 5.
Δ: Two scratches are observed in the evaluation of n = 5.
X: Three or more scratches are observed in the evaluation of n = 5.

(5) Curling The curl is measured using the curl measurement template of Method A in “Measurement Method of Curling of Photographic Film” of JIS K-7619-1988.
The curl size of the film after being conditioned for 10 hours under the conditions of 25 ° C. and 60% RH is expressed by the following formula.
Formula: Carl = 1 / R
In the formula, R represents a radius of curvature (m).
Here, the curl “+” means a curl in which the coating side of the film is inside the curve, and “−” means a curl in which the coating side is outside the curve.
In the present invention, when the curl is expressed by the above formula, the value is ◯ when it is within the range of −5 to +5, and × when it is not.

(6) Brittleness A film sample is cut into 35 mm x 120 mm, left to stand for 2 hours at a temperature of 25 ° C and a relative humidity of 60%, and then measured for the diameter of curvature at which cracks start to occur when rolled into a cylinder. Can be evaluated.
The crack resistance of the film of the present invention is preferably 50 mm or less, more preferably 40 mm or less (◯), and the curvature diameter at which cracking occurs when the coating layer side is rolled outward. The thickness is most preferably 30 mm or less (◎). A level of △ or higher was regarded as acceptable.

  As is apparent from Table 2, the optical film having an antiglare layer formed using the curable composition of the present invention is excellent in antiglare property, black tightening, hardness, curl and brittleness, and has a low average reflectance.

[Example 2]
An antiglare film was produced in the same manner as in Example 1 except that the antireflective antireflection film described in Example 1 was not provided with a low refractive index layer. Compared with the anti-glare antireflection film of Example 1, the anti-glare film of the present invention had an integrated reflectance of 4.4 to 4.6%, which deteriorated the feeling of black tightening and increased the reflection. However, as compared with the anti-glare film of the comparative example, a result of excellent black tightening and anti-glare property was obtained.

Example 3
Iodine is adsorbed on polyvinyl alcohol and stretched on one side of a polarizer prepared by dipping in a 1.5 mol / L, 55 ° C. NaOH aqueous solution for 2 minutes, neutralized, washed with water, and 80 μm thick triacetyl. A cellulose film (TAC-TD80U, manufactured by FUJIFILM Corporation) is attached, and each film of the film samples (saponified) in Examples 1 and 2 is attached to the other surface to protect both sides of the polarizer. Thus, a polarizing plate was produced.
The thus-prepared polarizing plate is a liquid crystal display device of a notebook personal computer equipped with a transmission type TN liquid crystal display device so that the antiglare layer or the low refractive index layer is the outermost surface (a polarization separation film having a polarization selection layer). When attached to the polarizing plate on the viewing side of D-BEF made by Sumitomo 3M Co., Ltd. between the backlight and the liquid crystal cell), the anti-glare property and black tightening are excellent, and the background reflection is extremely low. As a result, a display device having excellent bright room contrast and a very high display quality was obtained.

Example 4
The protective film on the liquid crystal cell side of the polarizing plate on the viewing side of the transmission type TN liquid crystal cell to which the respective films of the samples of the present invention in Examples 1 and 2 are attached, and the protective film on the liquid crystal cell side of the polarizing plate on the backlight side As an optical compensation film (Wide View Film Ace, manufactured by Fuji Film Co., Ltd.), it has excellent anti-glare properties, black tightening, extremely little background reflection, excellent bright room contrast, A liquid crystal display device having a very wide viewing angle, excellent visibility, and high display quality was obtained.

Example 5
Polarized light in which the polarizing plate provided on the VA liquid crystal display device (LC-26GD3 manufactured by Sharp) was peeled off while leaving the retardation film, and the polarizing plate of the present invention was attached to the product instead of the polarizing plate. When pasted so as to coincide with the plate, a display device with excellent display quality was obtained, which was excellent in antiglare property and black tightening, had very little background reflection, and had excellent bright room contrast.
It was also confirmed that the display using the polarizing plate of the present invention has a high glare prevention effect and a very good display performance with excellent contrast in the oblique direction.

Example 6
The polarizing plate provided in the IPS type liquid crystal display device (Th-26LX300, manufactured by Matsushita) is peeled off. Instead, the polarizing plate of the present invention is attached so that the transmission axis of the polarizing plate matches the polarizing plate attached to the product. As a result, it was possible to obtain a display device with excellent display quality, which has excellent antiglare properties, black tightening, very little background reflection, and excellent bright room contrast.

Example 7
When each film of the sample of the present invention in Examples 1 and 2 was bonded to a glass plate on the surface of an organic EL display device via an adhesive, reflection on the glass surface was suppressed, and a display device with high visibility. was gotten.

Example 8
Using each film of the sample of the present invention in Examples 1 and 2, a polarizing plate having the optical film of the present invention on one side was prepared, and on the opposite side of the polarizing plate on the side having the optical film of the present invention. Laminating the λ / 4 plate and pasting it on the glass plate on the surface of the organic EL display device so that the optical film side of the present invention is the outermost surface, the surface reflection and the reflection from the inside of the surface glass are cut, A display with extremely high visibility was obtained.

It is a figure explaining the method to measure the average inclination angle of the optical film of this invention.

Claims (7)

  An optical film having an antiglare layer comprising a resin obtained by curing a reactive polymer having a maleimide group in the side chain and not having an alkali-soluble group and particles having an average particle diameter of 3 to 15 μm on a transparent support.   The optical film according to claim 1, wherein the reactive polymer further has an ethylenically unsaturated group.   The optical film according to claim 1, wherein the antiglare layer further comprises a resin obtained by curing a reactive compound having a (meth) acrylate group.   The optical film according to claim 1, further comprising a layer having a lower refractive index than the antiglare layer.   The optical film according to any one of claims 1 to 4, wherein the integrated reflectance is 3.0% or less.   A polarizing plate comprising a polarizing film and two protective films protecting both surfaces of the polarizing film, wherein at least one of the protective films is the optical film according to claim 1.   The image display apparatus which has the optical film in any one of Claims 1-5, or the polarizing plate of Claim 6.

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