JP2014202853A - Antireflection film, polarizing plate with antireflection film, and transmissive liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antireflection film having excellent hard coat property, transparency, scratch resistance and blocking resistance, and to provide a polarizing plate with an antireflection film and a transmissive liquid crystal display.SOLUTION: The antireflection film comprises a transparent substrate 11, a hard coat layer 12 on at least one surface of the transparent substrate 11, a high refractive index layer 13 on the hard coat layer 12, and a low refractive index layer 14 on the high refractive index layer 13. The high refractive index layer 13 includes high refractive index microparticles 131 and microparticles 132 having an average particle diameter 0.8 to 1.2 times as the total film thickness of the high refractive index layer 13 and the low refractive index layer 14. A refractive index n(Ha) of the hard coat layer 12, a refractive index n(Hi) of the high refractive index layer, and a refractive index n(L) of the low refractive index layer 14 are in a relationship of n(L)<n(Ha)<n(Hi). On a surface of the low refractive index layer 14, the center line average height is 0.003 to 0.020 μm and the average interval of projections and recesses is 0.030 to 1.000 mm; and the antireflection film has a haze value of 0.3% or less.

Description

  The present invention relates to an antireflection film having excellent hard coat properties, transparency and scratch resistance, and also excellent in blocking resistance, and a polarizing plate with an antireflection film and a transmissive liquid crystal display using the antireflection film About.

  Generally, a display is used in an environment where external light or the like is incident, regardless of whether the display is used indoors or outdoors. Incident light such as external light is specularly reflected on the display surface and the like, and the reflected image thereby mixes with the display image, thereby degrading the screen display quality. For this reason, it is essential to provide an antireflection function to the display surface and the like, and there is a demand for higher performance of the antireflection function and to combine it with functions other than the antireflection function.

  In general, the antireflection function can be obtained by forming a multilayer film made of a transparent thin film such as a metal oxide as an antireflection layer on a transparent substrate. As a method for forming a multilayer film, a dry coating method such as a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method has been proposed. In addition, as a method for forming the antireflection layer, a wet coating method capable of increasing the area, continuously producing, and reducing the cost has been proposed.

  In addition, since these antireflection layers have a relatively soft surface, a hard coat layer generally made of a polymer of an acrylic polyfunctional compound is provided to provide surface hardness, and the antireflection layer is provided thereon. The method of forming is used.

  In addition, when used on the display surface, the antireflection film is required to have high transparency in order to increase visibility. In order to improve the transparency of the antireflection film, there is a method of smoothing the surface of the antireflection film and eliminating scattering of external light.

  However, with this method, the slipperiness of the film is poor due to its smoothness, and when the films are stacked or rolled, blocking (sticking) occurs, and the film surface becomes rough when peeling. . Thus, as an improved method of such blocking, there are a method of sandwiching a spacer such as a tape at both ends of the film, a method of giving fine irregularities on the film surface, and the like.

JP 2003-045234 A JP 2005-144858 A JP 2012-27401 A JP 2012-133079 A

  However, in these methods, the process of removing the tape at the time of film processing is complicated, and there is a problem that the transparency of the film is deteriorated by providing fine irregularities on the film surface.

  The present invention has been made to solve the above problems, and has an antireflection film having excellent hard coat properties, transparency and scratch resistance, and also excellent in blocking resistance, and the antireflection film. An object of the present invention is to provide a polarizing plate with an antireflection film and a transmissive liquid crystal display.

  In order to solve the above problems, the antireflection film of the present invention is an antireflection film, comprising a transparent substrate, a hard coat layer on at least one surface of the transparent substrate, and a high height on the hard coat layer. A refractive index layer and a low refractive index layer are provided on the high refractive index layer, and the high refractive index layer is a combination of the high refractive index fine particles and the thicknesses of the high refractive index layer and the low refractive index layer. Including a fine particle having an average particle diameter of 0.8 to 1.2 times the film thickness, a refractive index n (Hard) of the hard coat layer, a high refractive index layer refractive index n (High), and a low refractive index layer N (Low) is n (Low) <n (Hard) <n (High), and the centerline average height (Ra) of the surface of the low refractive index layer is 0.003 to 0.020 μm. And the average interval (Sm) of the irregularities on the surface of the low refractive index layer is 0.030 to 1.000 mm, Haze value of antireflection film is equal to or less than 0.3%.

  Moreover, the polarizing plate with an antireflection film of the present invention comprises the above antireflection film and a polarizing plate disposed on the side opposite to the surface on which the hard coat layer of the transparent base material of the antireflection film is formed. It is characterized by having.

  Furthermore, the transmissive liquid crystal display of the present invention includes the above-described polarizing plate with an antireflection film, a liquid crystal cell, a polarizing plate, and a backlight unit, and a surface having an antireflection film in the polarizing plate with an antireflection film; The liquid crystal cell, the polarizing plate, and the backlight unit are held in this order on the opposite surface side.

  According to the present invention, an antireflection film having excellent hard coat properties, transparency and scratch resistance, and also excellent in blocking resistance, a polarizing plate with an antireflection film and a transmission type using the antireflection film A liquid crystal display can be provided.

Schematic sectional view showing an antireflection film according to Embodiment 1 of the present invention. Schematic sectional view showing a polarizing plate with an antireflection film according to Embodiment 2 of the present invention The schematic sectional drawing which shows the transmissive liquid crystal display provided with the polarizing plate with an antireflection film based on Embodiment 3 of this invention. The schematic sectional drawing which shows the transmissive liquid crystal display provided with the polarizing plate with an antireflection film based on Embodiment 4 of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic cross-sectional view showing an antireflection film 1 according to Embodiment 1 of the present invention. As shown in FIG. 1, the antireflection film 1 includes a hard coat layer 12 formed from a hard coat layer forming coating solution, high refractive index fine particles 131, and fine particles 132 on at least one surface of a transparent substrate 11. A high refractive index layer 13 formed from a coating solution for forming a high refractive index layer containing, and a low refractive index layer 14 formed from a coating solution for forming a low refractive index layer containing fine particles of low refractive index 141 were sequentially laminated. It is a laminate.

  FIG. 1 is an example of the antireflection film 1 in which a hard coat layer 12, a high refractive index layer 13, and a low refractive index layer 14 are formed only on the upper surface (front surface) of the transparent substrate 11.

  First, the transparent substrate 11 will be described. As the transparent substrate 11, films made of various organic polymers can be used. For example, the base material normally used for optical members, such as a display, can be used. As the transparent substrate 11, in consideration of optical properties such as transparency and refractive index of light, and various physical properties such as impact resistance, heat resistance and durability, polyolefins such as polyethylene and polypropylene, polyethylene terephthalate, Polyesters such as polyethylene naphthalate, celluloses such as triacetyl cellulose, diacetyl cellulose and cellophane, polyamides such as 6-nylon and 6,6-nylon, acrylics such as polymethyl methacrylate, polystyrene, polyvinyl chloride, polyimide , Polyvinyl alcohol, polycarbonate, an organic polymer such as ethylene vinyl alcohol can be used. In particular, a cellulose film such as a triacetyl cellulose film can be suitably used. Cellulosic films have little birefringence, and are excellent in optical properties such as transparency, refractive index and dispersion, and various physical properties such as impact resistance, heat resistance and durability. Furthermore, the cellulose-based film is most preferably used because it is easily dissolved or swelled by a solvent.

  Various stabilizers, ultraviolet absorbers, plasticizers, lubricants, colorants, antioxidants, flame retardants, and the like may be added to the transparent substrate 11. Moreover, the thickness of the transparent base material 11 is not specifically limited. However, the thickness of the transparent substrate 11 is preferably 20 μm or more and 200 μm or less. However, when a triacetyl cellulose film is used as the transparent substrate 11, the thickness of the transparent substrate 11 is preferably 40 μm or more and 80 μm or less.

  Next, the hard coat layer 12 formed on the transparent substrate 11 will be described. In order to form the hard coat layer 12, first, a coating film is formed using a hard coat layer forming coating solution containing a binder matrix forming material and a solvent that dissolves or swells the transparent substrate 11. As a coating method of the hard coat layer forming coating solution, for example, a wet film forming method is adopted, and the hard coat layer forming coating solution is applied onto the transparent substrate 11 to form a coating film on the transparent substrate 11. To do. Thereafter, the hard coat layer 12 can be formed by irradiating the coating film with ionizing radiation and curing the coating film.

  The coating liquid for forming a hard coat layer preferably contains an acrylic material that is an ionizing radiation curable material as a binder matrix forming material. Acrylic materials are synthesized from monofunctional or polyfunctional (meth) acrylate compounds such as (meth) acrylic acid esters of polyhydric alcohols, diisocyanates and polyhydric alcohols, and hydroxy esters of (meth) acrylic acid. Such a polyfunctional urethane (meth) acrylate compound can be used. In addition to these, as ionizing radiation curable materials, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. should be used. Can do.

  In the present invention, “(meth) acryl” means both “acryl” and “methacryl”, “(meth) acrylate” means both “acrylate” and “methacrylate”, and “(meth) acrylate” The term “) acryloyl” refers to both “acryloyl” and “methacryloyl”. For example, “urethane (meth) acrylate” indicates both “urethane acrylate” and “urethane methacrylate”.

  Examples of the monofunctional (meth) acrylate compound 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 (meta) ) Acrylate, ethylene oxide modified phenoxy (meth) acrylate, propylene oxide modified phenoxy (meth) acrylate, nonylphenol (meth) acrylate, ethylene oxide modified nonylphenol (meth) acrylate, propylene oxide modified nonylphenol (meth) acrylate, methoxydiethylene glycol (meth) Acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (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, octafluoropropyl (meth) acrylate, 2 -Adamantane derivative mono (meth) acrylates such as adamantyl acrylate having a monovalent mono (meth) acrylate derived from adamantane and adamantanediol.

  Examples of the bifunctional (meth) acrylate compound include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, and 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, di (meth) acrylate, such as hydroxypivalic acid neopentyl glycol di (meth) acrylate.

  Examples of the trifunctional or higher functional (meth) acrylate compound include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, and tris 2-hydroxyethyl. 3 such as tri (meth) acrylate such as isocyanurate tri (meth) acrylate and glycerol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate Functional (meth) acrylate compounds, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra Trifunctional or more polyfunctional (meth) such as (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane hexa (meth) acrylate Examples thereof include acrylate compounds and polyfunctional (meth) acrylate compounds in which a part of these (meth) acrylates is substituted with an alkyl group or ε-caprolactone.

  Among acrylic materials, a polyfunctional urethane acrylate is preferably used because the desired molecular weight and molecular structure can be designed and the physical properties of the hard coat layer 12 to be formed can be easily balanced. Can be used. The urethane acrylate is obtained by reacting a polyhydric alcohol, a polyvalent isocyanate, and a hydroxyl group-containing acrylate.

  As the solvent contained in the hard coat layer forming coating solution, a solvent that dissolves or swells the transparent substrate 11 is used. The adhesion between the transparent substrate 11 and the hard coat layer 12 can be improved by forming the hard coat layer 12 using a hard coat layer forming coating solution containing a solvent that dissolves or swells the transparent substrate 11. it can. That is, the hard coat layer 12 in which the components of the transparent substrate 11 and the hard coat layer 12 are mixed can be formed, and the occurrence of interference unevenness can be prevented in the obtained antireflection film 1.

  When a cellulose film is used as the transparent substrate 11, examples of the solvent for dissolving or swelling the cellulose film surface include dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, Ethers such as 1,3-dioxolane, 1,3,5-trioxane, tetrahydrofuran, anisole and phenetole, and acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methyl Ketones such as cyclohexanone, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, propion brewed ethyl, n-pentyl acetate, Beauty γ- esters such as butyrolactone, further methyl cellosolve, cellosolve, butyl cellosolve, cellosolve such as cellosolve acetate and the like, can be used in combination these alone, or two or more kinds. Further, it is preferable to use at least one of methyl acetate, ethyl acetate, methyl ethyl ketone, acetylacetone, acetone, and cyclohexanone.

  Further, quaternary ammonium cations or conductive metal fine particles may be added to the hard coat layer 12 to impart conductivity to the hard coat layer 12.

  The hard coat layer 12 is formed by a wet coating method, such as a dip coating method, a spin coating method, a flow coating method, a spray coating method, a roll coating method, a gravure roll coating method, an air doctor coating method, a blade coating method. , Wire doctor coating method, knife coating method, reverse coating method, transfer roll coating method, micro gravure coating method, kiss coating method, cast coating method, slot orifice coating method, calendar coating method, die coating method, etc. It can be formed by applying a hard coat layer forming coating solution on at least one surface of the transparent substrate 11. In particular, since the hard coat layer 12 is thin and needs to be formed uniformly, it is preferable to use a microgravure coating method. Moreover, when it becomes necessary to form a thick layer as the hard coat layer 12, it is preferable to use a die coating method.

As a method for curing the coating film when forming the hard coat layer 12, for example, ultraviolet irradiation, heating, or the like can be employed. In the case of ultraviolet irradiation, a high pressure mercury lamp, a halogen lamp, a xenon lamp, a fusion lamp, or the like can be used. It is preferable that the ultraviolet irradiation amount is usually 100 to 800 mJ / cm ² .

  If the film thickness of the hard coat layer 12 is 3 μm or more, the strength is sufficient, but it is preferably in the range of 5 μm or more and 10 μm or less from the viewpoint of coating accuracy and handling. If the thickness of the hard coat layer 12 exceeds 10 μm, the transparent substrate 11 may be warped, distorted, or broken due to curing shrinkage. Moreover, it is very preferable as the hard coat layer 12 when the film thickness of the hard coat layer 12 is in the range of 5 μm or more and 7 μm or less.

Next, the high refractive index layer 13 formed on the hard coat layer 12 will be described. The high refractive index layer 13 has an average particle diameter of 0.8 to 1.2 times the total thickness of the high refractive index fine particles 131 and the total thickness of the high refractive index layer 13 and the low refractive index layer 14. A coating liquid for forming a high refractive index layer containing fine particles 132 having the above can be applied to the surface of the hard coat layer 12 and formed by a wet film formation method. At this time, the film thickness (d ₁ ) of the single layer of the high refractive index layer 13 is obtained by multiplying the film thickness (d ₁ ) by the refractive index (n ₁ ) of the high refractive index layer 13 ( n ₁ d ₁ ) is preferably designed to be equal to half the wavelength of visible light. As the coating solution for forming a high refractive index layer, a liquid in which high refractive index fine particles 131 are dispersed in a binder matrix forming material can be used.

As the high refractive index fine particles 131, for example, fine particles made of a high refractive index material such as ZrO ₂ , TiO ₂ , NbO, ITO, ATO, SbO ₂ , Sb ₂ O ₃ , SnO ₂ , In ₂ O ₃ , and ZnO are used. be able to.

  The average particle diameter of the high refractive index fine particles 131 is preferably 1 nm or more and 100 nm or less. When the average particle diameter of the high refractive index fine particles 131 exceeds 100 nm, light is remarkably reflected by Rayleigh scattering, the haze value of the high refractive index layer 13 is increased, and the transparency of the antireflection film 1 may be reduced. is there. On the other hand, when the average particle diameter of the high refractive index fine particles 131 is less than 1 nm, there is a possibility that problems such as nonuniformity of particles in the high refractive index layer 13 may occur due to aggregation of the particles.

  The fine particles 132 have an average particle diameter of 0.8 to 1.2 times the total thickness of the high refractive index layer 13 and the low refractive index layer 14, and preferably the antireflection film 1. The haze value is not particularly limited as long as the haze value can fall within the range described below. As the fine particles 132, for example, translucent organic resin particles such as polymethyl methacrylate fine particles and polymethyl methacrylate-polystyrene copolymer fine particles, inorganic fillers having a size that does not cause visible light scattering such as silica, and the like are used. Can do.

  The average particle diameter of the fine particles 132 is 0.8 to 1.2 times, preferably 0.9 to 1.1, of the total thickness of the high refractive index layer 13 and the low refractive index layer 14. Is double. When the average particle diameter of the fine particles 132 is less than 0.8 times the total thickness of the high refractive index layer 13 and the low refractive index layer 14, the fine particles 132 are buried in the binder matrix. Consequently, the surface of the antireflection film 1 cannot be provided with unevenness, and the effect of improving the blocking resistance cannot be exhibited. On the other hand, when the average particle diameter of the fine particles 132 exceeds 1.2 times the total thickness of the high refractive index layer 13 and the low refractive index layer 14, the surface of the antireflection film 1 has large unevenness. Therefore, the surface is easily scratched by the uneven portion.

  The content of the fine particles 132 is 0.5 to 3.0 parts by weight, preferably 0.8 to 2.5 parts by weight with respect to 100 parts by weight of the total solid content of the coating liquid for forming a high refractive index layer. When the content of the fine particles 132 is less than 0.5 parts by weight, the unevenness enough to prevent blocking cannot be imparted to the surface of the antireflection film 1. On the other hand, when the content of the fine particles 132 exceeds 3.0 parts by weight, it becomes difficult to disperse the fine particles 132, thereby causing uneven distribution of the fine particles 132.

  The fine particles 132 having an average particle diameter of 0.8 to 1.2 times the total thickness of the high refractive index layer 13 and the low refractive index layer 14 are formed for the high refractive index layer. In the case where the surface of the antireflection film 1 is roughened by adding to the coating liquid for forming the hard coat layer instead of adding to the coating liquid, if the hard coat layer 12 does not have a certain thickness, the hard coat properties Is not expressed. Therefore, in order to give unevenness to the surface of the antireflection film 1, it is necessary to increase the particle diameter of the fine particles 132 to be added. Here, when the particle diameter of the fine particles 132 is increased, there arises a problem that the haze value of the antireflection film 1 is increased. Further, fine particles 132 that are 0.8 to 1.2 times the total thickness of the high refractive index layer 13 and the low refractive index layer 14 are added to the low refractive index layer 14 that is the outermost surface. In addition, by adding to the internal high-refractive index layer 13, unevenness on the surface of the antireflection film 1 becomes gentle, and scratches due to unevenness can be prevented.

  The binder matrix forming material for forming the high refractive index layer 13 includes an ionizing radiation curable material. As the ionizing radiation curable material, a polyfunctional monomer having two or more (meth) acryloyl groups in one molecule or an ionizing radiation curable resin containing a monofunctional monomer is used. As the ionizing radiation curable material, for example, an acrylic material that is a monofunctional or polyfunctional (meth) acrylate compound exemplified as the ionizing radiation curable material used for the hard coat layer 12 can be used.

  Among acrylic materials, a polyfunctional urethane acrylate is preferably used because the desired molecular weight and molecular structure can be designed, and the physical properties of the formed high refractive index layer 13 can be easily balanced. Can be used. The urethane acrylate is obtained by reacting a polyhydric alcohol, a polyvalent isocyanate, and a hydroxyl group-containing acrylate.

  In addition, a solvent can be added to the coating liquid for forming a high refractive index layer as necessary. Examples of the solvent include aromatic hydrocarbons such as toluene, xylene, cyclohexane and cyclohexylbenzene, hydrocarbons such as n-hexane, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, dioxane, dioxolane. , Ethers such as trioxane, tetrahydrofuran, anisole and phenetole, and methyl isobutyl ketone, methyl butyl ketone, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone Ketones, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, propionic acid From among esters such as til, n-pentyl acetate, and γ-ptyrolactone, cellosolves such as methyl cellosolve, cellosolve, butyl cellosolve, cellosolve acetate, alcohols such as methanol, ethanol, isopropyl alcohol, water, etc. It can be appropriately selected and used in consideration of coating suitability and the like.

  When an ionizing radiation curable material is used as the binder matrix forming material and the high refractive index layer 13 is formed by irradiation with ultraviolet rays, a photopolymerization initiator is added to the coating solution for forming the high refractive index layer. As the photopolymerization initiator, for example, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, and the like can be used.

  As a method for forming the high refractive index layer 13, a high refractive index layer forming coating solution is applied to the surface of the hard coat layer 12 to form the high refractive index layer 13, and a vacuum deposition method. However, the method is not particularly limited, but can be divided into a vacuum film forming method for forming the high refractive index layer 13 in a vacuum such as a sputtering method and a CVD method. However, in the present invention, it is preferable to employ a wet film forming method from the viewpoint that the antireflection film 1 can be produced at low cost.

Next, the low refractive index layer 14 formed on the high refractive index layer 13 will be described. The low refractive index layer 14 can be formed by applying a low refractive index layer forming coating liquid containing the low refractive index fine particles 141 to the surface of the high refractive index layer 13 and performing wet film formation. At this time, the film thickness (d ₂ ) of the single layer of the low refractive index layer 14 that is the antireflection layer is obtained by multiplying the film thickness (d ₂ ) by the refractive index (n ₂ ) of the low refractive index layer 14. The optical film thickness (n ₂ d ₂ ) is preferably designed to be equal to ¼ of the wavelength of visible light. As the coating solution for forming a low refractive index layer, a coating liquid in which low refractive index fine particles 141 are dispersed in a binder matrix forming material can be used.

As the low refractive index fine particles 141, for example, low refraction such as LiF, MgF, 3NaF.AlF or AlF (all having a refractive index of 1.4), or Na ₃ AlF ₆ (cryolite, refractive index of 1.33) or the like. Fine particles made of a rate material can be used. Moreover, the silica particle which has a space | gap inside particle | grains can be used suitably. The silica particles having voids inside the particles can have a void portion having a refractive index of air (about 1), and thus can be made into low refractive index fine particles having a very low refractive index. Specifically, porous silica particles and silica particles having a shell structure can be used.

  The average particle diameter of the low refractive index fine particles 141 is preferably 1 nm or more and 100 nm or less. When the average particle diameter of the low refractive index fine particles 141 exceeds 100 nm, light is remarkably reflected by Rayleigh scattering, and the low refractive index layer 14 may be whitened to lower the transparency of the antireflection film 1. On the other hand, when the average particle diameter of the low refractive index fine particles 141 is less than 1 nm, there is a possibility that problems such as non-uniformity of particles in the low refractive index layer 14 may occur due to aggregation of the particles.

  The binder matrix forming material for forming the low refractive index layer 14 includes an ionizing radiation curable material. As the ionizing radiation curable material, a polyfunctional monomer having two or more (meth) acryloyl groups in one molecule or an ionizing radiation curable resin containing a monofunctional monomer is used. As the ionizing radiation curable material, acrylic materials exemplified as the ionizing radiation curable material used for the high refractive index layer 13 can be used.

  Among acrylic materials, a polyfunctional urethane acrylate is preferably used because the desired molecular weight and molecular structure can be designed, and the physical properties of the low refractive index layer 14 to be formed can be easily balanced. Can be used. The urethane acrylate is obtained by reacting a polyhydric alcohol, a polyvalent isocyanate, and a hydroxyl group-containing acrylate.

  In addition, a solvent and various additives can be added to the coating liquid for low refractive index layer formation as needed. As the solvent, for example, those exemplified as the solvent used for the high refractive index layer 13 can be used. Examples of the additive include a surface conditioner, a leveling agent, a refractive index adjuster, an adhesion improver, and a photosensitizer.

  When an ionizing radiation curable material is used as the binder matrix forming material and the low refractive index layer 14 is formed by irradiating ultraviolet rays, a photopolymerization initiator is added to the low refractive index layer forming coating solution. As a photoinitiator, what was illustrated as a photoinitiator added to the coating liquid for high refractive index layer 13 formation can be used.

  As a method for forming the low refractive index layer 14, a method exemplified as a method for forming the high refractive index layer 13 by applying a coating solution for forming a low refractive index layer on the surface of the high refractive index layer 13 may be adopted. it can.

  The heights of the hard coat layer refractive index n (Hard), the high refractive index layer refractive index n (High), and the low refractive index layer refractive index n (Low) are n (Low) <n (Hard) <n ( High). If this is not satisfied, a good antireflection function cannot be obtained.

  In the antireflection film 1, between the transparent substrate 11 and the hard coat layer 12, or between the hard coat layer 12 and the high refractive index layer 13, and between the high refractive index layer 13 and the low refractive index layer 14. Another functional layer may be provided between them. Examples of other functional layers include an electromagnetic shielding layer having electromagnetic shielding performance, an infrared absorbing layer having infrared absorbing performance, and an ultraviolet absorbing layer having ultraviolet absorbing performance.

  The antireflection film 1 thus obtained has a center line average height (Ra) of the surface of the low refractive index layer 14 of preferably 0.003 to 0.020 μm, more preferably 0.005 to 0.015 μm, and The average interval (Sm) of the irregularities on the surface of the low refractive index layer 14 is preferably 0.030 to 1.000 mm, more preferably 0.050 to 0.800 mm. Further, the haze value of the antireflection film 1 is preferably 0.3% or less, and more preferably 0.25% or less. When the center line average height (Ra) on the surface of the low refractive index layer 14 is less than 0.003 μm, or when the average interval (Sm) of the irregularities on the surface of the low refractive index layer 14 exceeds 1.000 mm, the antireflection film There is a possibility that the surface of 1 becomes flat and blocking is likely to occur. On the other hand, when the centerline average height (Ra) of the surface of the low refractive index layer 14 exceeds 0.020 μm, or when the average interval (Sm) of irregularities on the surface of the low refractive index layer 14 is less than 0.030 mm, the surface There is a possibility that the antireflection film 1 appears to be whitened due to the unevenness. Moreover, when the haze value of the antireflection film 1 exceeds 0.3%, the transparency of the antireflection film may be lowered.

  The antireflection film 1 can be suitably used as a part of a display member or an image device.

(Embodiment 2)
FIG. 2: is a schematic sectional drawing which shows the polarizing plate 200 with an antireflection film which concerns on Embodiment 2 of this invention provided with the antireflection film 1 which concerns on Embodiment 1. FIG.

  As illustrated in FIG. 2, the polarizing plate 200 with an antireflection film includes an antireflection film 1 and a polarizing plate 2. Specifically, the polarizing plate 2 composed of the polarizing layer 23 and the transparent substrate 21 is disposed on the surface of the transparent substrate 11 of the antireflection film 1 where the hard coat layer 12 is not formed. That is, a hard coat layer 12, a high refractive index layer 13, and a low refractive index layer 14 are laminated in this order from one side of the transparent substrate 11 (the upper surface in FIG. 2) from the transparent substrate 11 side. On the other surface of the material 11 (the lower surface in FIG. 2), a polarizing layer 23 and a transparent substrate 21 are laminated in this order from the transparent substrate 11 side. In addition, these polarizing layers 23 and the transparent base material 21 are not specifically limited, What is normally used for a polarizing plate with an antireflection film can be used suitably.

(Embodiment 3)
FIG. 3 is a schematic cross-sectional view showing an example of a transmissive liquid crystal display 300 including the polarizing plate 200a with an antireflection film according to Embodiment 3 of the present invention.

  The transmissive liquid crystal display 300 includes a polarizing plate 200a with an antireflection film, a liquid crystal cell 3, a polarizing plate 4, and a backlight unit 5. The antireflection film 1 is formed in the polarizing plate 200a with an antireflection film. The liquid crystal cell 3, the polarizing plate 4, and the backlight unit 5 are held in this order on the side opposite to the surface that is provided. The liquid crystal cell 3 is held on the side opposite to the side on which the hard coat layer 12 is formed with respect to the transparent substrate 11 in the polarizing plate 200a with an antireflection film. The antireflection film-attached polarizing plate 200 a includes an antireflection film 1 and a polarizing plate 2 a on the transparent base material 11 side of the antireflection film 1. The polarizing plate 2a is formed by laminating a transparent substrate 22, a polarizing layer 23, and a transparent substrate 21 in order from the transparent substrate 11 side. The liquid crystal cell 3 is held on the surface side opposite to the surface on which the low refractive index layer 14 of the polarizing plate 200a with antireflection film is formed, that is, on the transparent substrate 21 side. At this time, in the transmissive liquid crystal display 300, the antireflection film 1 side is the observation side, that is, the display surface.

  The transmissive liquid crystal display 300 includes the transparent base material 11 of the antireflection film 1 and the transparent base material 22 of the polarizing plate 2a separately.

  The backlight unit 5 includes a light source and a light diffusion plate (not shown). Although not shown, the liquid crystal cell 3 has a structure in which an electrode is provided on one transparent base material, an electrode and a color filter are provided on the other transparent base material, and liquid crystal is sealed between both electrodes. . In the polarizing plate 2 a provided so as to sandwich the liquid crystal cell 3, the polarizing layer 23 is sandwiched between the transparent substrate 21 and the transparent substrate 22, and in the polarizing plate 4, the transparent substrate 41 and the transparent substrate The polarizing layer 43 is sandwiched between the material 42.

(Embodiment 4)
FIG. 4 is a schematic cross-sectional view showing another example of a transmissive liquid crystal display provided with polarizing plate 200 with an antireflection film according to Embodiment 4 of the present invention.

  A transmissive liquid crystal display 400 shown in FIG. 4 includes a polarizing plate 200 with an antireflection film, a liquid crystal cell 3, a polarizing plate 4, and a backlight unit 5. The liquid crystal cell 3, the polarizing plate 4, and the backlight unit 5 are held in this order on the surface opposite to the surface on which the film is formed. The polarizing plate with antireflection film 200 includes an antireflection film 1 and a polarizing plate 2 on the transparent base material 11 side of the antireflection film 1. In the polarizing plate 2, a polarizing layer 23 and a transparent substrate 21 are laminated in order from the transparent substrate 11 side. The liquid crystal cell 3 is held on the surface side opposite to the surface on which the low refractive index layer 14 of the polarizing plate 200 with an antireflection film is formed, that is, on the transparent substrate 21 side. At this time, in the transmissive liquid crystal display 400, the antireflection film 1 side is the observation side, that is, the display surface.

  In the transmissive liquid crystal display 400, a polarizing layer 23 and a transparent substrate 22 are provided in this order as the polarizing plate 2 on the surface of the antireflection film 1 on which the hard coat layer 12 is not formed, that is, the surface of the transparent substrate 11. It has been.

  Similar to the transmissive liquid crystal display 300, the backlight unit 5 includes a light source and a light diffusion plate (not shown). Although not shown, the liquid crystal cell 3 has a structure in which an electrode is provided on one transparent base material, an electrode and a color filter are provided on the other transparent base material, and liquid crystal is sealed between both electrodes. . In the polarizing plate 2 (a part of the polarizing plate 200 with an antireflection film) provided so as to sandwich the liquid crystal cell 3, a polarizing layer 23 is sandwiched between the transparent substrate 21 and the transparent substrate 11, and the polarizing plate 4. , The polarizing layer 43 is sandwiched between the transparent base material 41 and the transparent base material 42.

  Note that the transmissive liquid crystal displays 300 and 400 of the present invention may include other functional members. Other functional members include, for example, a diffusion film, a prism sheet, a brightness enhancement film for effectively using light emitted from a backlight, and a phase difference film for compensating for a phase difference between a liquid crystal cell and a polarizing plate. However, it is not limited to these.

(Example)
Hereinafter, preparation examples of a coating liquid for forming a hard coat layer, a coating liquid for forming a high refractive index layer, and a coating liquid for forming a low refractive index layer, and examples and comparative examples using these are shown.

Preparation Example 1 (hard coat layer forming coating solution)
15.0 parts by weight of pentaerythritol triacrylate (PE3A), 15.0 parts by weight of pentaerythritol tetraacrylate (PE4A), 25 parts by weight of urethane acrylate (UA), and a photopolymerization initiator (Irgacure 184 (Irg. 184)) 1 part by weight of Ciba Specialty Chemicals Co., Ltd.) and 0.1 part by weight of a leveling agent (BYK-340, manufactured by Big Chemie Japan Co., Ltd.), these are 43.9 parts by weight of methyl ethyl ketone (MEK). The coating liquid 1 for hard-coat layer formation was prepared by melt | dissolving in a part. Table 1 shows the composition of the hard coat layer forming coating solution.

Preparation Example 2 (Coating liquid 1 for forming a high refractive index layer)
ATO fine particle dispersion (average particle size 5 nm, solid content 20%, solvent ethanol) 20.35 parts by weight, dipentaerythritol hexaacrylate (DPHA) 5.81 parts by weight, polymerization initiator (Irgacure 184, Ciba Specialty) -Chemicals Co., Ltd. 0.58 weight part and silica fine particle dispersion (average particle diameter 200nm, solid content 30%, solvent ethanol) 0.58 weight part, ethanol (EtOH) 72.67 which is a solvent. The coating solution 1 for forming a high refractive index layer was prepared by diluting with parts by weight.

Preparation Example 3 (High Refractive Index Layer Coating Liquid 2)
ATO fine particle dispersion (average particle size 5 nm, solid content 20%, solvent ethanol) 20.35 parts by weight, dipentaerythritol hexaacrylate 5.81 parts by weight, polymerization initiator (Irgacure 184, Ciba Specialty Chemicals ( Co., Ltd.) 0.58 parts by weight and silica fine particle dispersion (average particle size 230 nm, solid content 30%, solvent ethanol) 0.87 parts by weight were diluted with 72.67 parts by weight of ethanol as a solvent. A coating liquid 2 for forming a high refractive index layer was prepared.

Preparation Example 4 (Coating liquid 3 for forming a high refractive index layer)
ATO fine particle dispersion (average particle size 5 nm, solid content 20%, solvent ethanol) 20.35 parts by weight, dipentaerythritol hexaacrylate 5.81 parts by weight, polymerization initiator (Irgacure 184, Ciba Specialty Chemicals ( Co., Ltd.) 0.58 parts by weight and silica fine particle dispersion (average particle size 250 nm, solid content 30%, solvent ethanol) 0.58 parts by weight were diluted with 72.67 parts by weight of ethanol as a solvent. A coating solution 3 for forming a high refractive index layer was prepared.

Preparation Example 5 (High refractive index layer forming coating solution 4)
ATO fine particle dispersion (average particle size 5 nm, solid content 20%, solvent ethanol) 20.35 parts by weight, dipentaerythritol hexaacrylate 5.81 parts by weight, polymerization initiator (Irgacure 184, Ciba Specialty Chemicals ( Co., Ltd.) 0.58 parts by weight and silica fine particle dispersion (average particle size 300 nm, solid content 30%, solvent ethanol) 0.29 parts by weight were diluted with 72.67 parts by weight of ethanol as a solvent. A coating solution 4 for forming a high refractive index layer was prepared.

Preparation Example 6 (Coating liquid 5 for forming a high refractive index layer)
ATO fine particle dispersion (average particle size 5 nm, solid content 20%, solvent ethanol) 20.35 parts by weight, dipentaerythritol hexaacrylate 5.81 parts by weight, polymerization initiator (Irgacure 184, Ciba Specialty Chemicals ( Co., Ltd.) 0.58 parts by weight and silica fine particle dispersion (average particle size 100 nm, solid content 30%, solvent ethanol) 0.58 parts by weight were diluted with 72.67 parts by weight of ethanol as a solvent. A coating solution 5 for forming a high refractive index layer was prepared.

Preparation Example 7 (High refractive index layer-forming coating solution 6)
ATO fine particle dispersion (average particle size 5 nm, solid content 20%, solvent ethanol) 20.35 parts by weight, dipentaerythritol hexaacrylate 5.81 parts by weight, polymerization initiator (Irgacure 184, Ciba Specialty Chemicals ( Co., Ltd.) 0.58 parts by weight and silica fine particle dispersion (average particle size 200 nm, solid content 30%, solvent ethanol) 0.15 parts by weight were diluted with 72.67 parts by weight of ethanol as a solvent. A coating liquid 6 for forming a high refractive index layer was prepared.

Preparation Example 8 (Coating liquid 7 for forming a high refractive index layer)
ATO fine particle dispersion (average particle size 5 nm, solid content 20%, solvent ethanol) 20.35 parts by weight, dipentaerythritol hexaacrylate 5.81 parts by weight, polymerization initiator (Irgacure 184, Ciba Specialty Chemicals ( Co., Ltd.) 0.58 parts by weight and silica fine particle dispersion (average particle size 250 nm, solid content 30%, solvent ethanol) 1.74 parts by weight were diluted with 72.67 parts by weight of ethanol as a solvent. A coating liquid 7 for forming a high refractive index layer was prepared.

Preparation Example 9 (High Refractive Index Layer Coating Liquid 8)
ATO fine particle dispersion (average particle size 5 nm, solid content 20%, solvent ethanol) 20.35 parts by weight, dipentaerythritol hexaacrylate 5.81 parts by weight, polymerization initiator (Irgacure 184, Ciba Specialty Chemicals ( Co., Ltd.) 0.58 parts by weight and 0.58 parts by weight of silica fine particle dispersion (average particle size 500 nm, solid content 30%, solvent ethanol) were diluted with 72.67 parts by weight of ethanol as a solvent. A coating liquid 8 for forming a high refractive index layer was prepared.

  Table 2 shows the compositions of the coating solutions 1 to 8 for forming the high refractive index layer.

Preparation Example 10 (Coating liquid for forming a low refractive index layer)
Porous silica fine particle dispersion (average particle size 50 nm, solid content 20%, solvent methyl isobutyl ketone) 32.08 parts, dipentaerythritol hexaacrylate 1.68 parts, polymerization initiator (Irgacure 184, Ciba 0.07 part by weight of Specialty Chemicals Co., Ltd.) and 0.18 part by weight of a leveling agent (BYK-UV3500, manufactured by Big Chemie Japan Co., Ltd., solid content> 97%), methyl isobutyl ketone as a solvent (MIBK) Diluted with 66.00 parts by weight to prepare a coating solution for forming a low refractive index layer. Table 3 shows the composition of the coating solution for forming the low refractive index layer.

Example 1 (Preparation of antireflection film)
An antireflection film having the configuration shown in FIG. 1 was produced. As the transparent substrate, a triacetyl cellulose film (manufactured by Fuji Film Co., Ltd.) having a film thickness of 80 μm was used.

(1) Formation of hard coat layer The coating liquid for forming a hard coat layer obtained above was applied on one surface of a transparent substrate and dried in an oven at 80 ° C for 60 seconds. After drying, using a UV irradiation device (Fusion UV Systems Japan Co., Ltd., light source H bulb), UV irradiation was performed at an irradiation dose of 200 mJ / m ² to form a transparent hard coat layer having a dry film thickness of 5 μm.

(2) Formation of High Refractive Index Layer The high refractive index layer forming coating solution 1 was applied on the hard coat layer formed above so that the film thickness after drying was 150 nm, thereby forming a coating film. Using a UV irradiation device, UV irradiation was performed at an irradiation dose of 200 mJ / m ² to cure the coating film to form a high refractive index layer.

(3) Formation of low-refractive index layer On the high-refractive index layer formed above, a coating solution for forming a low-refractive index layer was applied so that the film thickness after drying was 100 nm. Using an ultraviolet irradiation device, ultraviolet rays were irradiated at an irradiation dose of 200 mJ / m ² to cure the coating film to form a low refractive index layer, thereby obtaining an antireflection film.

Example 2 (Preparation of antireflection film)
An antireflection film was obtained in the same manner as in Example 1 except that the coating solution 2 for forming a high refractive index layer was used instead of the coating solution 1 for forming a high refractive index layer.

Example 3 (Preparation of antireflection film)
An antireflection film was obtained in the same manner as in Example 1 except that the coating solution 3 for forming a high refractive index layer was used instead of the coating solution 1 for forming a high refractive index layer.

Example 4 (Preparation of antireflection film)
An antireflection film was obtained in the same manner as in Example 1 except that the coating solution 4 for forming a high refractive index layer was used instead of the coating solution 1 for forming a high refractive index layer.

Comparative Example 1 (Preparation of antireflection film)
An antireflection film was obtained in the same manner as in Example 1, except that the coating solution 5 for forming a high refractive index layer was used instead of the coating solution 1 for forming a high refractive index layer.

Comparative Example 2 (Preparation of antireflection film)
An antireflection film was obtained in the same manner as in Example 1, except that the coating solution 6 for forming a high refractive index layer was used instead of the coating solution 1 for forming a high refractive index layer.

Comparative Example 3 (Preparation of antireflection film)
An antireflection film was obtained in the same manner as in Example 1, except that the coating solution 7 for forming a high refractive index layer was used instead of the coating solution 1 for forming a high refractive index layer.

Comparative Example 4 (Preparation of antireflection film)
An antireflection film was obtained in the same manner as in Example 1 except that the coating solution 8 for forming a high refractive index layer was used instead of the coating solution 1 for forming a high refractive index layer.

  The antireflection films obtained in Examples 1 to 4 and Comparative Examples 1 to 4 were evaluated by the following methods.

(Haze value)
About the anti-reflective film obtained above, the haze value was measured based on the method of JIS K 7105-1981 using the image clarity measuring device (Nippon Denshoku Industries Co., Ltd. make, NDH-2000). .

(Average luminous reflectance)
About the surface of the low refractive index layer of the antireflection film obtained above, the spectral reflectance at an incident angle of 5 ° was measured using an automatic spectrophotometer (manufactured by Hitachi, Ltd., U-4000). Further, the average luminous reflectance was obtained from the obtained spectral reflectance curve. In the measurement, a matte black paint was applied to the surface of the triacetylcellulose film, which is a transparent substrate, on which the antireflection layer was not formed, and antireflection treatment was performed.

(Whitening)
Light from a fluorescent lamp was applied to the antireflection film obtained above, and the light diffusion state on the surface of the hard coat layer was evaluated. Judgment criteria are shown below.
○: Light diffusion is small and the hard coat layer surface is not whitened ×: The hard coat layer surface is whitened

(Abrasion resistance)
The surface of the low refractive index layer of the obtained antireflection film was rubbed 10 times with steel wool (Nihon Steel Wool Co., Ltd., Bonstar # 0000) at a load of 250 g / cm ² to visually check for the presence or absence of scratches. It was observed and evaluated. Judgment criteria are shown below.
○: No scratch was confirmed ×: Scratch was confirmed

(Center line average height of low refractive index layer surface (Ra))
For the low refractive index layer of the antireflection film obtained above, the surface of the low refractive index layer is measured using a non-contact surface / layer cross-sectional shape measurement system VertScan 2.0 high precision fine shape measuring instrument (Surfcoder ET4000A manufactured by Kosaka Laboratory). The centerline average height (Ra) of was measured.

(Average spacing (Sm) of surface irregularities of the low refractive index layer)
For the low refractive index layer of the antireflection film obtained above, the surface of the low refractive index layer is measured using a non-contact surface / layer cross-sectional shape measurement system VertScan 2.0 high precision fine shape measuring instrument (Surfcoder ET4000A manufactured by Kosaka Laboratory). The average interval (Sm) of the irregularities was measured.

(Blocking resistance)
The antireflection film obtained above was cut into a 10 cm square, and five of the cut films were stacked on a glass plate and allowed to stand at 50 ° C. for 24 hours. Thereafter, the area of the blocking portion in the film area (100 cm ² ) was visually observed and evaluated. Judgment criteria are shown below.
○: The area of the blocking portion in the film area is less than 50%. ×: The area of the blocking portion in the film area is 50% or more.

  The evaluation results obtained above are shown in Table 4 below.

  From the results shown in Table 4, it can be seen that the antireflection films obtained in Examples 1 to 4 have excellent hard coat properties, transparency and scratch resistance, and are also excellent in blocking resistance. .

  On the other hand, the antireflection films obtained in Comparative Examples 1 and 2 are inferior in blocking resistance, and the antireflection films obtained in Comparative Examples 3 and 4 are whitened and inferior in transparency. I understand.

  The antireflection film of the present invention can be suitably used for display screens of displays such as LCD, PDP, CRT, projection display, EL display and the like.

DESCRIPTION OF SYMBOLS 1 Antireflection film 11, 21, 22, 41, 42 Transparent base material 12 Hard coat layer 13 High refractive index layer 131 High refractive index fine particle 132 Fine particle 14 Low refractive index layer 141 Low refractive index fine particle 2, 2a Polarizing plate 23, 43 Polarizing layer 200, 200a Polarizing plate with antireflection film 3 Liquid crystal cell 300, 400 Transmission type liquid crystal display 4 Polarizing plate 5 Backlight unit

Claims (3)

An anti-reflection film,
A transparent substrate;
A hard coat layer on at least one surface of the transparent substrate;
A high refractive index layer on the hard coat layer;
A low refractive index layer on the high refractive index layer,
The high refractive index layer is
High refractive index fine particles,
Including fine particles having an average particle diameter of 0.8 to 1.2 times the total thickness of the high refractive index layer and the low refractive index layer,
The refractive index n (Hard) of the hard coat layer, the refractive index n (High) of the high refractive index layer, and the refractive index n (Low) of the low refractive index layer are n (Low) <n (Hard). <N (High),
The centerline average height (Ra) of the surface of the low refractive index layer is 0.003 to 0.020 μm, and the average interval (Sm) of the irregularities on the surface of the low refractive index layer is 0.030 to 1. An antireflection film having a thickness of .000 mm and a haze value of the antireflection film of 0.3% or less.   The antireflection film according to claim 1, and a polarizing plate disposed on a surface opposite to the surface on which the hard coat layer of the transparent substrate of the antireflection film is formed. A polarizing plate with an antireflection film.   The polarizing plate with an antireflection film according to claim 2, a liquid crystal cell, a polarizing plate, and a backlight unit, and a surface opposite to a surface having the antireflection film in the polarizing plate with an antireflection film. In addition, the liquid crystal cell, the polarizing plate, and the backlight unit are held in this order.

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