JP7349235B2 - anti-reflection film - Google Patents

Description

The present invention relates to an antireflection film.

Anti-reflection films are used in various display devices such as cathode tube displays (CRTs), plasma display panels (PDPs), liquid crystal displays (LCDs), projection displays, electroluminescent displays (ELDs), touch panels, optical lenses, and eyeglasses. It is used in various fields such as lenses, antireflection treatment in photolithography processes, and antireflection treatment on the surface of solar panels.

As an antireflection film, for example, Patent Document 1 discloses that a fluorine-based inorganic compound having a photorefractive index smaller than that of the plastic film is bound on at least one side of a flexible transparent plastic film with an inorganic binder. An antireflection film is disclosed that is characterized by forming a baked coating. The antireflection film disclosed in Patent Document 1 can maintain excellent antireflection effects over a long period of time.

Patent No. 2923565

However, when the antireflection film disclosed in Patent Document 1 is installed on the display surface of a display device such as a cathode tube display (CRT) or a liquid crystal display (LCD), it is difficult to see when the display is viewed diagonally and from the front. There is a problem in that the chromaticity changes greatly when viewed, and the perceived color tone changes depending on the viewing angle.

The present invention was made in view of the above problems, and even when a display equipped with an anti-reflection film is viewed from an angle, the change in chromaticity is smaller than when viewed from the front. An object of the present invention is to provide an antireflection film that can effectively suppress changes in the visible color tone depending on the viewing angle.

Further, the above-mentioned object of the present invention is an anti-reflection film comprising a transparent base film and an anti-reflection layer formed on at least one of the transparent base films, wherein the anti-reflection layer is formed on the transparent base film. It is constructed by laminating a medium refractive index layer, a high refractive index layer, and a low refractive index layer from the film side, and the thickness of the medium refractive index layer is 85 nm to 150 nm, and the refractive index is 1.55 to 1.55. 1.60, the film thickness of the high refractive index layer is 20 nm to 55 nm, and the refractive index is 1.65 to 1.75, and the film thickness of the low refractive index layer is 60 nm to 150 nm. , and the refractive index is 1.30 to 1.50, and the visibility reflectance of the antireflection film regarding regular reflection at an incident angle of 5° is 0.6% or less, and the luminous efficiency reflectance regarding regular reflection at an incident angle of 5° is The difference between the maximum value and minimum value of reflectance (%) in the wavelength range of 450 nm to 750 nm is 0.75 or less, and the maximum value of reflectance (%) in the wavelength range of 400 nm to 700 nm regarding specular reflection at an incident angle of 45°. The difference in minimum value is 1.5 or less, and the reflected hue is (-1.0≦a*≦1.0, -2.0≦b*≦2 in the entire range of incident angles from 35° to 45°. .0) .

Also,The low refractive index layer includes a first low refractive index layer provided on the high refractive index layer side and a second low refractive index layer provided on the first low refractive index layer, and the first low refractive index layer is provided on the first low refractive index layer. The thickness of the second low refractive index layer is 50 nm to 100 nm, and the refractive index is 1.30 to 1.40, and the thickness of the second low refractive index layer is 10 nm to 50 nm, and the refractive index is 1.30 to 1.40. The refractive index is preferably higher than that of the first low refractive index layer.

According to the present invention, even when a display equipped with an anti-reflection film is viewed from an angle, the change in chromaticity is smaller than when viewed from the front, and the visible color changes depending on the viewing angle. It is possible to provide an anti-reflection film that can effectively suppress changes in response to the change in temperature.

FIG. 1 is a schematic cross-sectional view of an antireflection film according to the present invention. It is a graph regarding reflectance concerning an example. It is a graph regarding the reflectance based on a comparative example. It is a graph showing the relationship between a* and b* at each incident angle for Examples. It is a graph showing the relationship between a* and b* at each incident angle for a comparative example. FIG. 3 is a schematic cross-sectional view of a modified example of the antireflection film according to the present invention.

EMBODIMENT OF THE INVENTION Hereinafter, the antireflection film based on embodiment of this invention is demonstrated with reference to an accompanying drawing. Note that in the drawings, parts are enlarged or reduced in order to facilitate understanding of the configuration. The antireflection film 1 according to the present invention can be applied to various display devices such as a cathode tube display (CRT), a plasma display panel (PDP), a liquid crystal display (LCD), a projection display, an electroluminescent display (ELD), and a touch panel. It is used in various fields such as optical lenses, eyeglass lenses, anti-reflection treatment in photolithography processes, and anti-reflection treatment on the surface of solar panels. At least one surface of the material film 2 is provided with a medium refractive index layer 3, a high refractive index layer 4, and a low refractive index layer 5. Here, the laminate consisting of three layers, the medium refractive index layer 3, the high refractive index layer 4, and the low refractive index layer 5, is an antireflection layer that exhibits antireflection properties. Note that in this embodiment, three antireflection layers are arranged on one side of the transparent base film 2 in the order of a medium refractive index layer 3, a high refractive index layer 4, and a low refractive index layer 5. In addition to this antireflection layer, three second antireflection layers are further arranged on the other side of the transparent base film 2 in the order of a medium refractive index layer, a high refractive index layer, and a low refractive index layer. can also be adopted.

The transparent base film 2 includes a film body 21, a first hard coat layer 22, and a second hard coat layer 23. As the film body 21, it is preferable to use a transparent organic polymer material. The transparent organic polymer material is a film made of an organic polymer compound, taking into consideration optical properties such as transparency and light refractive index, as well as physical properties such as impact resistance, heat resistance, and durability. I can do things. The organic polymer compound is not particularly limited as long as it is a transparent organic polymer, but in order to exhibit excellent antireflection performance, the transmittance of the transparent substrate 2 must be 80% or more, and more preferably 86% or more. The haze is preferably 2.0% or less, more preferably 1.0% or less, and the refractive index is preferably 1.40 to 1.70. Examples of organic polymer compounds include polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polyethylene naphthalate, celluloses such as triacetylcellulose, diacetylcellulose, and cellophane, 6-nylon, and 6,6-nylon. Examples include polyamides such as polyamides, acrylics such as polymethyl methacrylate, polystyrene, polyvinyl chloride, polyimide, polyvinyl alcohol, polycarbonate, ethylene vinyl alcohol, and the like. Particularly preferred are polyethylene terephthalate, triacetyl cellulose, polycarbonate, and polymethyl methacrylate.

The first hard coat layer 22 is formed on one side of the film body 21, and the second hard coat layer 23 is formed on the other side of the film body 21. The medium refractive index layer 3 is laminated on the second hard coat layer 23, and the high refractive index layer 4 is laminated on the medium refractive index layer 3. Moreover, the low refractive index layer 5 is laminated on the high refractive index layer 4.

The thickness of the film body 21 in the transparent base film 2 is usually about 13 to 400 μm, preferably about 25 to 300 μm. In addition, the film body 21 has a refractive index of 1.40 to 1.70, preferably 1.0 to 1.70, in order to increase the adhesion with the first hard coat layer 22 and the second hard coat layer 23 and to reduce interference. An anchor layer of .50 to 1.65 may also be provided. The film body 21 may contain various additives. Examples of such additives include ultraviolet absorbers, antistatic agents, stabilizers, plasticizers, lubricants, flame retardants, and the like.

The first hard coat layer 22 and the second hard coat layer 23 are layers for ensuring the surface strength of the antireflection film 1. It is preferable to form the coat layer 23 in advance. The refractive index of the first hard coat layer 22 is preferably within the range of 1.50 to 1.70. Further, the refractive index of the second hard coat layer 23 is preferably within the range of 1.50 to 1.70. Note that if the refractive index of the first hard coat layer 22 and the second hard coat layer 23 is not optimized to the refractive index of the film body 21, the refractive index of the first hard coat layer 22 and the second hard coat layer 23 (second hard coat layer This is not preferable because interference caused by the difference in the refractive index of the layer 23) may cause noticeable interference unevenness and may make it difficult to design the hue of the reflection characteristics of the antireflection film 1.

The thickness of both the first hard coat layer 22 and the second hard coat layer 23 is preferably 1 to 50 μm. If the thickness of the hard coat layer is less than 1 μm, it is not preferable because sufficient surface strength cannot be obtained. On the other hand, when the film thickness exceeds 50 μm, problems such as a decrease in bending resistance occur, which is not preferable.

Moreover, as a material for forming the first hard coat layer 22 and the second hard coat layer 23, an ionizing radiation curing material or a thermosetting material can be used. For example, an acrylic material can be used as the ionizing radiation-curable material. Examples of acrylic materials include monofunctional, bifunctional, trifunctional or higher functional (meth)acrylate compounds such as acrylic or methacrylic esters of polyhydric alcohols, diisocyanates and polyhydric alcohols, and hydroxy esters of acrylic or methacrylic acids. Polyfunctional urethane (meth)acrylate compounds such as those synthesized from can be used. In addition to these, polyether resins, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, etc. having acrylate functional groups can be used as ionizing radiation-curable materials. can. In the present invention, "(meth)acrylate" refers to both "acrylate" and "methacrylate." For example, "urethane (meth)acrylate" refers to both "urethane acrylate" and "urethane methacrylate."

Furthermore, since the ionizing radiation-curable material is cured by ultraviolet rays, a photopolymerization initiator is added to the coating solution for forming the hard coat layer. The photopolymerization initiator may be one that generates radicals when irradiated with ultraviolet light, such as acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, and thioxanthones. I can do it.

Further, as the thermosetting material, for example, organopolysiloxane can be used. The layer consisting of organopolysiloxane is a layer obtained by hydrolysis and dehydration polycondensation using organosiloxane as a starting material according to a wet method, and forms a polymer network with a three-dimensional network structure based on a siloxane (Si-O) skeleton. It is composed of

Furthermore, a solvent and various additives can be added to the coating liquid for forming a hard coat layer, if necessary. Examples of solvents include aromatic hydrocarbons such as toluene, xylene, cyclohexane, and cyclohexylbenzene, hydrocarbons such as n-hexane, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, dioxane, dioxolane, and trioxane. , tetrahydrofuran, anisole, and phenethole, and ketones such as methylisobutylketone, methylbutylketone, acetone, methylethylketone, diethylketone, dipropylketone, diisobutylketone, cyclopentanone, cyclohexanone, methylcyclohexanone, and methylcyclohexanone. and esters such as ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone, as well as methyl cellosolve, cellosolve, It is appropriately selected from among cellosolves such as butyl cellosolve and cellosolve acetate, and alcohols such as methanol, ethanol, isopropyl alcohol, and butanol, taking into consideration suitability for coating. Moreover, a surface conditioner, a refractive index adjuster, an adhesion improver, a curing agent, etc. can also be added to the coating liquid as additives.

Further, other additives may be added to the coating liquid for forming the hard coat layer. Examples of additives include antifoaming agents, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, and polymerization inhibitors.

Further, it is practically preferable that the hardness of the first hard coat layer 22 and the second hard coat layer 23 is H or higher in terms of pencil hardness, but this is not limited to this because it is also influenced by the film body 21. The first hard coat layer 22 and the second hard coat layer 23 may be provided in direct contact with the film body 21, or may be provided on the film body 21 via a layer for improving adhesion to the film body 21. It's okay. Further, when forming the first hard coat layer 22 and the second hard coat layer 23, the surfaces may be made smooth.

Methods for forming the first hard coat layer 22 and the second hard coat layer 23 include a wet coating method, a dip coating method, a spin coating method, a flow coating method, a spray coating method, a roll coating method, and a gravure roll coating method. , air doctor coating method, blade coating method, wire doctor coating method, knife coating method, reverse coating method, transfer roll coating method, microgravure coating method, kiss coating method, cast coating method, slot orifice coating method, calendar coating method, A die coating method or the like can be employed, and the hard coat layer can be formed by applying a coating liquid for forming a hard coat layer onto the surface of the film body 21. In particular, since it is necessary to form thin and uniform layers for the first hard coat layer 22 and the second hard coat layer 23, it is preferable to use a microgravure coating method. Further, when it becomes necessary to form thick layers as the first hard coat layer 22 and the second hard coat layer 23, it is preferable to use a die coating method.

In this embodiment, as shown in FIG. 1, the first hard coat layer 22 and the second hard coat layer 23 are formed on both sides of the film body 21, respectively. The transparent base film 2 may be configured by omitting the hard coat layer or both hard coat layers.

Next, the medium refractive index layer 3 will be explained. The medium refractive index layer 3 is a layer containing an inorganic material, and can be formed by applying a medium refractive index layer forming coating liquid to the surface of the second hard coat layer 23 by a wet film forming method. Note that at this time, the thickness (d1) of the single medium refractive index layer is designed to be an optimal value by optical simulation. As the medium refractive index layer forming coating liquid, one in which high refractive index fine particles are dispersed in a binder matrix forming material can be used. The thickness (d1) of the medium refractive index layer 3 of the present invention is preferably within the range of 85 nm to 150 nm, more preferably within the range of 105 nm to 130 nm, in view of its properties as an optical interference layer. Further, the refractive index (n1) of the medium refractive index layer 3 is preferably within the range of 1.55 to 1.60. The refractive index (n1) of the medium refractive index layer 3 is adjusted to a value between the refractive index of the low refractive index layer 5 and the refractive index of the high refractive index layer 4.

Examples of the high refractive index fine particles dispersed in the medium refractive index layer forming coating liquid include ZrO ₂ , TiO ₂ , Nb ₂ O ₅ , ITO, ATO, Sb ₂ O ₅ , Sb ₂ O ₃ , SnO ₂ , In ₂ Inorganic fine particles made of a high refractive index material such as O ₃ or ZnO can be used. The shape of the high refractive index fine particles used in the present invention is not particularly limited, but preferably rice grain-like, spherical, cubic, spindle-like, or irregular shape. The inorganic fine particles in the present invention may be used alone, but two or more types can also be used in combination.

Further, the average particle diameter of the high refractive index fine particles is preferably 1 nm or more and 100 nm or less. When the average particle diameter of the high refractive index fine particles exceeds 100 nm, light is significantly reflected by Rayleigh scattering, the haze value of the medium refractive index layer 3 becomes high, and the transparency of the antireflection film 1 may decrease. . On the other hand, if the average particle diameter of the high refractive index fine particles is less than 1 nm, problems such as non-uniformity of particles in the medium refractive index layer 3 may occur due to particle aggregation.

Further, the binder matrix forming material for forming the medium refractive index layer 3 includes an ultraviolet curable material. As the ultraviolet curable material, an ultraviolet curable material containing a polyfunctional monomer having two or more (meth)acryloyl groups in one molecule or a monofunctional monomer is used. As the ultraviolet curable material, for example, an acrylic material that is a monofunctional or polyfunctional (meth)acrylate compound, which is exemplified as an ionizing radiation curable material used for the first and second hard coat layers 22 and 23, is used. be able to. Among acrylic materials, polyfunctional urethane acrylate is preferred because it allows the desired molecular weight and molecular structure to be designed, and it is possible to easily balance the physical properties of the medium refractive index layer 3 to be formed. Can be used. Urethane acrylate is obtained by reacting a polyhydric alcohol, a polyhydric isocyanate, and a hydroxyl group-containing acrylate.

Note that a solvent can be added to the coating liquid for forming a medium refractive index layer, if necessary. Examples of solvents include aromatic hydrocarbons such as toluene, xylene, cyclohexane, and cyclohexylbenzene, hydrocarbons such as n-hexane, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, dioxane, and dioxolane. , trioxane, tetrahydrofuran, anisole, and phenetol, as well as methyl isobutyl ketone, methyl butyl ketone, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl cyclohexanone, and methyl cyclohexanone. and esters such as ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, methyl propionate, ethyl propionate, n-pentyl acetate, and γ-butyrolactone, as well as methyl cellosolve, It can be appropriately selected and used from among cellosolves such as cellosolve, butyl cellosolve, and cellosolve acetate, alcohols such as methanol, ethanol, and isopropyl alcohol, and water, taking into consideration coating suitability and the like.

In addition, when an ultraviolet curable material is used as the binder matrix forming material for forming the medium refractive index layer 3 and the medium refractive index layer 3 is formed by irradiating ultraviolet rays, a coating liquid for forming the medium refractive index layer is used. A photoinitiator is added to the photopolymerization initiator. The photopolymerization initiator may be one that generates radicals when irradiated with ultraviolet light, and specific examples include acetophenone compounds, benzoin compounds, benzophenone compounds, oxime ester compounds, thioxanthone compounds, Examples include triazine compounds, phosphine compounds, quinone compounds, borate compounds, carbazole compounds, imidazole compounds, and titanocene compounds. Examples of acetophenone compounds include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-hydroxy Cyclohexylphenylketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane- An example is 1-on. Examples of benzoin compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzyl dimethyl ketal. Examples of benzophenone compounds include benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, and 4-benzoyl-4'-methyldiphenyl sulfide. Examples of oxime ester compounds include ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(0-acetyloxime), 1,2-octadione- Examples include 1-[4-(phenylthio)-, 2-(O-benzoyloxime)]. Examples of thioxanthone compounds include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, and 2,4-diisopropylthioxanthone. Examples of triazine compounds include 2,4,6-trichloro-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-(p-methoxyphenyl)-4,6-bis (trichloromethyl)-s-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-s-triazine, 2-pipenyl-4,6-bis(trichloromethyl)-s-triazine, 2 , 4-bis(trichloromethyl)-6-styryl s-triazine, 2-(naphth-1-yl)-4,6-bis(trichloromethyl)-s-triazine, 2-(4-methoxy-naphtho-1 -yl)-4,6-bis(trichloromethyl)-s-triazine, 2,4-trichloromethyl-(piperonyl)-6-triazine, 2,4-trichloromethyl(4'-methoxystyryl)-6-triazine etc. can be exemplified. Examples of the phosphine compounds include bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. Examples of the quinone compounds include 9,10-phenanthrenequinone, camphorquinone, and ethyl anthraquinone. The photopolymerization initiators may be used alone or in combination of two or more.

Further, other additives may be added to the coating liquid for forming the medium refractive index layer. Examples of additives include antifoaming agents, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, polymerization inhibitors, photosensitizers, and the like.

Methods for forming the medium refractive index layer 3 include a wet film forming method in which a medium refractive index layer forming coating liquid is applied to the surface of the second hard coat layer 23 to form the medium refractive index layer 3, and a method using a vacuum method. The method is divided into a vacuum film forming method for forming the medium refractive index layer 3 in vacuum, such as a vapor deposition method, a sputtering method, and a CVD method, but is not particularly limited. However, in the present invention, it is preferable to employ a wet film forming method because the antireflection film 1 can be manufactured at low cost.

Next, the high refractive index layer 4 formed on the medium refractive index layer 3 will be explained. The high refractive index layer 4 is a layer containing an inorganic material, and can be formed by applying a high refractive index layer forming coating liquid to the surface of the middle refractive index layer 3 and using a wet film forming method. Note that at this time, the film thickness (d2) of the single layer of high refractive index layer 4 is designed to be an optimal value by optical simulation. Further, the thickness (d2) of the high refractive index layer 4 is preferably within the range of 20 nm to 55 nm, more preferably within the range of 30 nm to 45 nm, in view of its properties as an optical interference layer.

The refractive index (n2) of the high refractive index layer 4 of the present invention is particularly preferably within the range of 1.65 to 1.75 from the viewpoint of suppressing discoloration of the antireflection film 1. The means for adjusting the refractive index (n2) of the high refractive index layer 4 is primarily the amount of high refractive index fine particles added. As the high refractive index fine particles, high refractive index materials described in the medium refractive index layer forming coating liquid can be used. Further, the high refractive index fine particles can be surface-treated with an inorganic compound and/or an organic compound described in the coating liquid for forming a medium refractive index layer.

The binder matrix forming material for forming the high refractive index layer 4 includes an ultraviolet curable material. As the ultraviolet curable material, an ionizing radiation curable resin containing a polyfunctional monomer having two or more (meth)acryloyl groups in one molecule or a monofunctional monomer is used. As the ultraviolet curable material, the acrylic material exemplified as the ultraviolet curable material used for the medium refractive index layer 3 can be used.

Note that a solvent and various additives can be added to the coating liquid for forming a high refractive index layer, if necessary. As the solvent, for example, those exemplified as the solvent used for the medium refractive index layer 3 can be used. Examples of additives include antifoaming agents, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, polymerization inhibitors, photosensitizers, and the like.

In addition, in the case where an ultraviolet curable material is used as the binder matrix forming material for forming the high refractive index layer 4 and the high refractive index layer 4 is formed by irradiating ultraviolet rays, the coating liquid for forming the high refractive index layer is A photoinitiator is added to the photopolymerization initiator. As the photopolymerization initiator, those exemplified as photopolymerization initiators added to the coating liquid for forming a medium refractive index layer can be used.

Methods for forming the high refractive index layer 4 include a wet film forming method in which a high refractive index layer forming coating liquid is applied to the surface of the medium refractive index layer 3 to form the high refractive index layer 4, and a vacuum evaporation method. The method is divided into a method using a vacuum film forming method in which the high refractive index layer 4 is formed in a vacuum, such as a method, a sputtering method, and a CVD method, but the method is not particularly limited. However, in the present invention, it is preferable to employ a wet film forming method because the antireflection film 1 can be manufactured at low cost.

Next, the low refractive index layer 5 formed on the high refractive index layer 4 will be explained. The low refractive index layer 5 is a hardened layer containing a binder resin and inorganic fine particles, and can be formed by applying a low refractive index layer forming coating liquid to the surface of the high refractive index layer 4 by a wet film forming method. . Note that at this time, the film thickness (d3) of the single layer of the low refractive index layer 5 is designed to be an optimal value by optical simulation. Further, the film thickness (d3) of the low refractive index layer 5 is preferably within the range of 60 nm to 150 nm, more preferably within the range of 90 nm to 130 nm, in view of its properties as an optical interference layer.

The refractive index (n3) of the low refractive index layer 5 of the present invention is preferably in the range of 1.30 to 1.50, more preferably 1.32 to 1.45. If the refractive index (n3) of the low refractive index layer 5 is as low as possible, it approaches the refractive index of air (refractive index = 1) and it is easier to achieve a low reflectance. Since it is necessary to add a large amount to the refractive index layer forming coating solution, the mechanical strength becomes low and scratches occur easily. On the other hand, when the refractive index (n3) of the low refractive index layer 5 exceeds 1.50, the difference in refractive index with air becomes large and the reflectance increases, which is not preferable.

The low refractive index fine particles contained in the low refractive index layer forming coating liquid include, for example, LiF, MgF, 3NaF・AlF, or AlF (all have a refractive index of 1.4), or Na ₃ AlF ₆ (cryolite, refractive Fine particles made of a material with a low refractive index such as 1.33) can be used. Furthermore, silica particles having voids inside the particles can be suitably used. Silica particles having voids inside the particles can have the refractive index of air (approximately 1.0) in the void portion, and therefore can be made into low refractive index fine particles having an extremely low refractive index. Specifically, porous silica particles and shell-structured silica particles can be used.

The average particle diameter of the low refractive index fine particles is preferably 1 nm or more and 100 nm or less. When the average particle diameter of the low refractive index fine particles exceeds 100 nm, light is significantly reflected due to Rayleigh scattering, and there is a possibility that the low refractive index layer 5 becomes white and the transparency of the antireflection film 1 decreases. On the other hand, if the average particle diameter of the low refractive index fine particles is less than 1 nm, problems such as non-uniformity of particles in the low refractive index layer 5 may occur due to particle aggregation.

As the binder matrix forming material for forming the low refractive index layer 5, an ultraviolet curable material or a thermosetting material can be used. ) An ionizing radiation curable resin containing a polyfunctional monomer having an acryloyl group or a monofunctional monomer is used. As the ultraviolet curable material, the acrylic material exemplified as the ultraviolet curable material used for the medium refractive index layer 3 can be used, and as the thermosetting material, for example, organopolysiloxane can be used. The layer consisting of organopolysiloxane is a layer obtained by hydrolysis and dehydration polycondensation using organosiloxane as a starting material according to a wet method, and forms a polymer network with a three-dimensional network structure based on a siloxane (Si-O) skeleton. It is composed of

Note that a solvent and various additives can be added to the low refractive index layer forming coating liquid for forming the low refractive index layer 5, if necessary. As the solvent, for example, those exemplified as the solvent used for the medium refractive index layer 3 can be used. Examples of additives include antifoaming agents, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, polymerization inhibitors, photosensitizers, and the like.

In addition, when an ultraviolet curable material is used as the binder matrix forming material for forming the low refractive index layer 5 and the low refractive index layer 5 is formed by irradiating ultraviolet rays, the coating liquid for forming the low refractive index layer is A photoinitiator is added to the photopolymerization initiator. As the photopolymerization initiator, those exemplified as photopolymerization initiators added to the coating liquid for forming a medium refractive index layer can be used.

As a method for forming the low refractive index layer 5, it is recommended to use a wet film forming method in which a coating liquid for forming a low refractive index layer is applied to the surface of the high refractive index layer 4, which is an inexpensive method for forming an antireflection film. This method is preferable because it can produce 1.

Here, if necessary, as shown in FIG. 1, the antireflection film 1 may be configured by providing a lubricant layer 6 on the low refractive index layer 5. The lubricant layer 6 is provided to protect the low refractive index layer 5 from dirt and improve scratch resistance. The lubricant layer 6 preferably contains a fluorine-containing silane compound in the composition for forming a lubricant coat layer, and is prepared by coating a solution of a silane compound having a fluoroalkyl group or a fluoroalkyl ether group. In particular, it is preferable that the fluorine-containing silane compound is polysilazane or alkoxysilane. Note that the thickness of the lubricant layer 6 is preferably 0.1 nm to 15 nm. Furthermore, it is preferably 1 nm to 10 nm.

Further, among the silane compounds having a fluoroalkyl group or a fluoroalkyl ether group, the fluoroalkyl group in the silane compound is bonded to one Si atom or less at a ratio of one or less to one Si atom, A silane compound in which the remainder is a hydrolyzable group or a siloxane bonding group is preferred. The hydrolyzable group mentioned here is, for example, a group such as an alkoxy group, which becomes a hydroxyl group by hydrolysis, whereby the silane compound forms a polycondensate.

For example, the above-mentioned silane compound is reacted with water (in the presence of an acid catalyst if necessary) at a temperature ranging from room temperature to 100° C. while distilling off the alcohol by-product. As a result, the alkoxysilane is (partially) hydrolyzed, a part of the condensation reaction occurs, and a hydrolyzate having a hydroxyl group can be obtained. The degree of hydrolysis and condensation can be appropriately adjusted by adjusting the amount of water to be reacted, but in the present invention, water is not actively added to the silane compound solution used for the lubricant layer 6, and after preparation, the silane compound solution is mainly During drying, it is preferable to dilute the solid content of the solution to a low value in order to cause a hydrolysis reaction with moisture in the air.

Preferably, in the composition for forming the lubricant layer 6, the above-mentioned silane compound having a fluoroalkyl group is represented by the following general formula (1), and the concentration of the silane compound is diluted to 0.01 to 5% by mass. It can be used as a solution.

General formula (1) CF ₃ (CF ₂ ) _m (CH ₂ ) _n -Si-(ORa) ₃
Here, m is an integer of 1 to 10, n is an integer of 0 to 10, and Ra is the same or different alkyl group.

In the compound represented by the general formula (1), Ra is preferably an alkyl group having 3 or less carbon atoms and consisting only of carbon and hydrogen, such as methyl, ethyl, and isopropyl.

These silane compounds having a fluoroalkyl group or a fluoroalkyl ether group that are preferably used in the present invention include CF ₃ (CH ₂ ) ₂ Si(OCH ₃ ) ₃ and CF ₃ (CH ₂ ) ₂ Si(OC ₂ H ₅ ). ₃ , _CF3 ( _{CH2 ) 2Si} ( _OC3H7 ) ₃ , CF3 _{( CH2} ) _2Si ( _OC4H9 ) _{3 , CF3} ( _CF2 ) ₅ ( _CH2 ) _2Si (OCH3 ₎ ) ₃ , CF ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ Si(OC ₂ H ₅ ) ₃ , CF ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ Si(OC ₃ H ₇ ) ₃ , CF ₃ (CF ₂ ) ₇ (CH2) ₂ Si(OCH ₃ ) ₃ , CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si(OC ₂ H ₅ ) ₃ , CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ Si(OC _{3 H7} ) ₃ , _CF3 ( _CF2 ) ₇ ( _CH2 ) _2Si ( _OCH3 )( _OC3H7 ) _{2 , CF3} ( _CF2 ) ₇ ( _{CH2 ) 2Si} ( _OCH3 ) _2OC3 H ₇ , CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ SiCH ₃ (OCH ₃ ) ₂ , CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ SiCH ₃ (OC ₂ H ₅ ) ₂ , CF ₃ (CF ₂ ) ₇ (CH ₂ ) ₂ SiCH ₃ (OC ₃ H ₇ ) ₂ , (CF ₃ ) ₂ CF(CF ₂ ) ₈ (CH ₂ ) ₂ Si(OCH ₃ ) ₃ , C ₇ F ₁₅ CONH(CH ₂ ) ₃ Si( _{OC2H5 ) 3} , _{C8F17SO2NH ( CH2 ) 3Si} ( _OC2H5 ) _{3 , C8F17} ( _CH2 ) _2OCONH ( _CH2 ) _3Si ( _{OCH3 ) 3} , _CF3 ( _CF2 ) ₇ ( _CH2 ) _2Si ( _CH3 )( _OCH3 ) ₂ , _CF3 ( _{CF2 ) 7} ( _CH2 ) _2Si ( _CH3 )( _OC2H5 ) ₂ , _CF3 ( _CF2 ) ₇ ( _CH2 ) _2Si ( _CH3 )( _{OC3H7 ) 2} , _CF3 ( _CF2 ) ₇ ( _CH2 ) _2Si ( _{C2H5 )} ( _OCH3 ) ₂ , _CF3 ( _CF2 ) ₇ ( _CH2 ) _2Si ( _C2H5 )( _{OC3H7 ) 2} , _CF3 ( _CH2 ) _2Si ( _{CH3 )} ( _OCH3 ) ₂ , _CF3 (CH2 ₎ ) ₂ Si(CH ₃ )(OC ₂ H ₅ ) ₂ , CF ₃ (CH ₂ ) ₂ Si(CH ₃ )(OC ₃ H ₇ ) ₂ , CF ₃ (CF ₂ ) ₅ (CH ₂ ) ₂ Si(CH ₃ )( _OCH3 ) ₂ , _CF3 ( _CF2 ) ₅ ( _CH2 ) _2Si ( _CH3 )( _OC3H7 ) _{2 , CF3} ( _CF2 ) _2O ( _CF2 ) ₃ ( _CH2 ) _2Si ( _OC3H7 ), _{C7F15CH2O ( CH2 ) 3Si ( OC2H5 ) 3 , C8F17SO2O ( CH2 ) 3Si ( OC2H5} ) ₃ , C ₈ F ₁₇ (CH ₂ ) ₂ OCHO(CH ₂ ) ₃ Si(OCH ₃ ) ₃ and the like, but are not limited thereto.

Examples of the fluorine-based silane compound include KP801M manufactured by Shin-Etsu Chemical Co., Ltd., Optool DSX manufactured by Daikin Industries, Ltd., and FG5010 manufactured by Fluoro Technology Co., Ltd., and the like.

EXAMPLES Specific aspects of the present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

(Example)
[Film body 21]
As the film body 21, a PET film ("Lumirror" manufactured by Toray Industries, Inc.) with a thickness of 188 μm and a width of 300 mm is prepared.

[Formation of first hard coat layer 22]
After coating "Opstar" (refractive index 1.5) manufactured by Arakawa Chemical Co., Ltd. on one side of the film body 21 using SA-203 Bar Coater ROD No. 10 manufactured by Tester Sangyo Co., Ltd., coat it with an organic solvent at 80°C for 2 minutes. evaporated. Next, a first hard coat layer 22 having a thickness of about 5 μm was formed by irradiating ultraviolet rays using a high-pressure mercury lamp.

[Formation of second hard coat layer 23]
After coating "Opstar" (refractive index 1.5) manufactured by Arakawa Chemical Co., Ltd. with SA-203 bar coater ROD No. 10 manufactured by Tester Sangyo Co., Ltd. on the opposite side of the film body 21 from the first hard coat layer 22. The organic solvent was evaporated at 80° C. for 2 minutes. Next, a second hard coat layer 23 having a thickness of about 5 μm was formed by irradiating ultraviolet rays using a high-pressure mercury lamp.

[Formation of medium refractive index layer 3 in antireflection layer]
"Liodurus" manufactured by Toyo Ink Co., Ltd. (refractive index 1.6) is diluted to a concentration of 6.0% by weight using methyl isobutyl ketone. Next, this paint was applied onto the second hard coat layer 23 using D-Bar #2 manufactured by OSG System Products Co., Ltd., and then the organic solvent was evaporated at 80° C. for 2 minutes. Next, a medium refractive index layer 3 of 125 nm was formed by irradiating ultraviolet rays using a high-pressure mercury lamp.

[Formation of high refractive index layer 4 in antireflection layer]
"Liodurus" manufactured by Toyo Ink Co., Ltd. (refractive index 1.7) is diluted to a concentration of 2.0% by weight using methyl isobutyl ketone. Next, this paint was applied onto the medium refractive index layer 3 using D-Bar #2 manufactured by OSG System Products Co., Ltd., and then the organic solvent was evaporated at 80° C. for 2 minutes. Next, a high refractive index layer 4 of 35 nm was formed by irradiating ultraviolet rays using a high-pressure mercury lamp.

[Formation of low refractive index layer 5 in antireflection layer]
"Opstar" manufactured by Arakawa Kogyo Co., Ltd. (refractive index 1.32) is diluted to a concentration of 3.5% by weight using methyl isobutyl ketone. Next, this paint was applied onto the high refractive index layer 4 using D-Bar #2 manufactured by OSG System Products Co., Ltd., and then the organic solvent was evaporated at 80° C. for 2 minutes. Next, a 115 nm low refractive index layer 5 was formed by irradiating ultraviolet rays using a high-pressure mercury lamp.

By obtaining the above manufacturing process, the reflection according to the embodiment consisting of the first hard coat layer 22 / film body 21 / second hard coat layer 23 / medium refractive index layer 3 / high refractive index layer 4 / low refractive index layer 5 A prevention film 1 was produced. The antireflection layer in the example has a three-layer structure consisting of medium refractive index layer 3/high refractive index layer 4/low refractive index layer 5.

(Comparative example)
[Film body 21]
As the film body 21, a PET film ("Lumirror" manufactured by Toray Industries, Inc.) with a thickness of 188 μm and a width of 300 mm is prepared.

[Formation of first hard coat layer 22]
After coating "Opstar" (refractive index 1.5) manufactured by Arakawa Chemical Co., Ltd. on one side of the film body 21 using SA-203 Bar Coater ROD No. 10 manufactured by Tester Sangyo Co., Ltd., coat it with an organic solvent at 80°C for 2 minutes. evaporated. Next, a first hard coat layer 22 having a thickness of about 5 μm was formed by irradiating ultraviolet rays using a high-pressure mercury lamp.

[Formation of second hard coat layer 23]
After coating "Opstar" (refractive index 1.5) manufactured by Arakawa Chemical Co., Ltd. with SA-203 bar coater ROD No. 10 manufactured by Tester Sangyo Co., Ltd. on the opposite side of the film body 21 from the first hard coat layer 22. The organic solvent was evaporated at 80° C. for 2 minutes. Next, a second hard coat layer 23 having a thickness of about 5 μm was formed by irradiating ultraviolet rays using a high-pressure mercury lamp.

[Formation of antireflection layer]
"Opstar" manufactured by Arakawa Kogyo Co., Ltd. (refractive index 1.32) is diluted to a concentration of 3.5% by weight using methyl isobutyl ketone. Next, this paint was applied onto the high refractive index layer 4 using D-Bar #2 manufactured by OSG System Products Co., Ltd., and then the organic solvent was evaporated at 80° C. for 2 minutes. Next, a single-layer antireflection layer having a thickness of 105 nm was formed by irradiating ultraviolet rays using a high-pressure mercury lamp.

An antireflection film according to a comparative example consisting of the first hard coat layer 22/film body 21/second hard coat layer 23/antireflection layer (single layer structure) was produced by the above production process.

[Evaluation of reflectance]
For the antireflection films of Examples and Comparative Examples, the visibility reflectance was calculated based on JIS Z8701. For the visibility reflectance, tristimulus values (XYZ) for standard light C are determined from the reflection spectrum of the antireflection layer in the range of 380 nm to 780 nm, and the value of Y becomes the visibility reflectance. Graphs regarding the reflectance of each antireflection film of Examples and Comparative Examples are shown in FIGS. 2 and 3. Here, FIG. 2 is a graph regarding the reflectance according to the example, with the horizontal axis representing the wavelength (nm) and the vertical axis representing the reflectance (%). The results for "reflectance ratio" and "reflectance ratio for specular reflection with incident angle of 45°" are also shown. In addition, FIG. 3 is a graph regarding the reflectance according to the comparative example, where the horizontal axis is the wavelength (nm) and the vertical axis is the reflectance (%). ” and “Incidence angle 45°: Reflectance related to specular reflection” are also shown. Further, Table 1 shows the values of visibility reflectance (incident angle of 5°: specular reflection) for the Examples and Comparative Examples. Further, Table 1 shows the maximum and minimum values of emissivity in the wavelength range of 450 nm to 750 nm for the examples and comparative examples in the case of regular reflection with an incident angle of 5°. Further, Table 1 shows the maximum and minimum values of reflectance in the wavelength range of 400 nm to 700 nm in the case of regular reflection with an incident angle of 45° for Examples and Comparative Examples. Here, the incident angle refers to the angle formed by the light incident on the surface of the antireflection film and an imaginary line perpendicular to the surface of the antireflection film.

Here, from Table 1, the values of visibility reflectance (incident angle 5°: specular reflection) for Examples and Comparative Examples are 0.23% and 0.16%, respectively, and both are 0.6% or less. It can be seen that the antireflection films according to the examples and comparative examples have excellent antireflection properties.

Further, from Table 1, in the example, the difference between the maximum value and minimum value of reflectance (%) in the wavelength range of 450 nm to 750 nm when the incident angle is 5° is 0.52 (0. 68-0.16), and the difference between the maximum and minimum reflectance (%) in the wavelength range of 400 nm to 700 nm at an incident angle of 45° is 1.14 (1.68- 0.46).

On the other hand, in the comparative example, the difference between the maximum value and minimum value of reflectance (%) in the wavelength range of 450 nm to 750 nm when the incident angle is 5 degrees is 1.01 (1.08-0. 07), the difference between the maximum and minimum reflectance (%) in the wavelength range of 400 nm to 700 nm at an incident angle of 45° is 1.83 (2.20-0.37). .

Furthermore, if we pay attention to the graph regarding the reflectance in the comparative example in FIG. 3, in the wavelength range of 400 nm to 800 nm, the reflectance shows a downwardly convex curve for both the case of an incident angle of 5° and the case of an incident angle of 45°. It can be seen that the trend is as shown. On the other hand, in the graph regarding the reflectance in the example of FIG. 4, when the incident angle is 5°, the reflectance changes almost flat in the wavelength range of 450 nm to 700 nm, and when the incident angle is 45°, the reflectance changes almost flatly. , it can be seen that the reflectance changes approximately flat in the wavelength range of 400 nm to 600 nm. In other words, in the antireflection film according to the example, at least in the wavelength range of 450 nm to 600 nm, the change in reflectance at each wavelength is extremely small between the incident angle of 5° and the incident angle of 45°. Therefore, compared to the antireflection film according to the comparative example, the antireflection film according to the example has a smaller visible color change depending on the viewing angle, and when the display equipped with the antireflection film is viewed from an angle. It can be seen that the change in chromaticity is small compared to when viewed from the front even when viewed from the front.

Here, from the results of Examples and Comparative Examples, the "difference between the maximum value and minimum value of reflectance (%) in the wavelength range 450 nm to 750 nm regarding specular reflection at an incident angle of 5°" is within a range of 0.75 or less. In this case, even when a display equipped with an antireflection film is viewed from an angle, it is thought that an effect can be obtained in that the change in chromaticity is smaller than when viewed from the front. Note that this value of "0.75" is the difference between the maximum value and minimum value of reflectance (%) in the wavelength range of 450 nm to 750 nm when the incident angle is 5 degrees in the example. 52" and the arithmetic mean value of "1.01" (0 .765).

In addition, from the results of Examples and Comparative Examples, the "difference between the maximum value and minimum value of reflectance (%) in the wavelength range 400 nm to 700 nm regarding specular reflection at an incident angle of 45°" is within a range of 1.5 or less. In this case, even when a display equipped with an antireflection film is viewed from an angle, it is thought that an effect can be obtained in that the change in chromaticity is smaller than when viewed from the front. Note that this value of "1.5" is the difference between the maximum value and minimum value of reflectance (%) in the wavelength range of 400 nm to 700 nm when the incident angle is 45 degrees in the example. 14" and the arithmetic mean value of "1.83" which is the difference between the maximum and minimum values of reflectance (%) in the wavelength range of 400 nm to 700 nm when the incident angle is 45° in the comparative example (1 .485).

[Evaluation of reflective hue]
Next, the surfaces of the antireflection films of Examples and Comparative Examples (the surface of the low refractive index layer 5 in the Examples, the surface of the single-layer antireflection layer in the Comparative Examples) were measured using a spectrophotometer (manufactured by Hitachi, Ltd.). , U-4100), the spectral reflectance at an incident angle of 5° to 45° is measured, and the hue of the reflected light is determined from the obtained spectral reflectance curve. , -15≦a*≦15, -15≦b*≦15. In addition, during the measurement, an adhesive layer was applied to the surface of the film body 21, which is a transparent support, on which the low refractive index layer 5 was not formed (in the comparative example, the surface on which the single-layer antireflection layer was not formed). A black acrylic plate was attached through the panel to prevent reflection. The measurement results are shown below as Table 2. In addition, based on the results in Table 2, the relationship between a* and b* at each incident angle for each of the examples and comparative examples is plotted in graphs with a* on the horizontal axis and b* on the vertical axis. Shown in Figure 5. Note that FIG. 4 is a graph regarding the example, and FIG. 5 is a graph regarding the comparative example.

First, from the results in Table 2, in the CIE1976L*a*b* color space, when viewed at each incident angle, both the example and the comparative example satisfy -15≦a*≦15, -15≦b*≦15. Therefore, it is recognized that coloring of reflected light is suppressed. However, if we pay attention to the graphs regarding a* and b* in the comparative examples shown in Table 2 and FIG. * has increased significantly from -10.27 (incidence angle 5°) to 6.79 (incidence angle 45°), and the visible color change is large as the viewing angle changes. I understand that. On the other hand, in the graphs regarding a* and b* in the examples shown in Table 2 and FIG. The value of b* is within the range of -5.71 (incident angle 0°) to 0.16 (incident angle 45°). It can be seen that even if the incident angle changes, the changes in both the a* and b* values are small. From this as well, it can be said that the antireflection film according to the example exhibits a small change in color tint that is visually recognized according to a change in the viewing angle.

Also, if we pay attention to the graphs regarding a* and b* in the examples and comparative examples in FIGS. 4 and 5, the antireflection films according to the examples have higher a* and b* exists near the origin (a*=0, b*=0). From this, it can be seen that the antireflection film according to the example can suppress the coloring of reflected light more effectively than the antireflection film according to the comparative example, and has excellent reflection characteristics.

In this way, even when the anti-reflection film according to the example is viewed from an angle, the change in chromaticity is smaller than when viewed from the front, and the visible color changes depending on the viewing angle. It can be seen that it can effectively prevent the reflected light from changing in color at any viewing angle, and can also effectively prevent the reflected light from being colored at any viewing angle.

In addition, sensory tests showed that the anti-reflection film of the example of the present invention can extremely effectively suppress the occurrence of coloring in reflected light when viewed from an angle (in the range of incident angle of 35° to 45°). Confirmed during (visual inspection). This can be seen from the fact that both a* and b* in the antireflection film according to the example exhibit values near 0. In order to effectively suppress the occurrence of coloring in reflected light when viewed from an angle, the reflected hue for at least one incident angle should be (-3.0 ≦a*≦3.0, −3.0≦b*≦3.0). In addition, in order to further suppress the reflected light from being colored, it is necessary that the reflected hue for at least one incident angle be (-1.0≦a*≦1.0 in the incident angle range of 35° to 45°. , −2.0≦b*≦2.0). In addition, in order to further suppress the reflected light from being colored when viewed from an angle, the reflected hue must be (-3.0≦a*≦3. 0, -3.0≦b*≦3.0), and more preferably (-1.0≦a*≦1.0, -2.0≦b*≦2. It is preferable to set the value to 0). Here, in order to effectively suppress the occurrence of coloring in the reflected light when viewed from an angle, the absolute values of a* and b* must be The lower the better. Focusing on the range of incidence from 35° to 45° in the results in Table 2, a* in the example shows a value around 0, whereas a* in the comparative example shows a value around 6 . From this, in order to suppress the coloration of reflected light when viewed from an angle, the absolute value of a* should be , is preferably equal to or less than "3", which is the arithmetic mean value of "0" and "6", and similarly, b* in the example shows a value around 0, whereas in the comparative example b* shows a maximum value of around 6 to 7, so in order to suppress the coloring of the reflected light when viewed from an angle, at least one incident angle in the incident angle range of 35° to 45° is necessary. Regarding the reflected hue at the corner, since it is considered preferable that the absolute value of b* be less than or equal to "3", which is the arithmetic mean value of "0" and "6", the above-mentioned reflected hue (-3. Boundary values of the numerical range (0≦a*≦3.0, -3.0≦b*≦3.0) are selected.

Although one embodiment of the antireflection film 1 according to the present invention has been described above, the specific configuration of the antireflection film 1 is not limited to the above embodiment. For example, the low refractive index layer 5 may be configured as a two-layer structure consisting of a first low refractive index layer 51 and a second low refractive index layer 52, as shown in the cross-sectional view of FIG. When the low refractive index layer 5 is configured as such a two-layer structure, it is preferable that the first low refractive index layer 51 is configured as a hardened layer containing a binder resin and inorganic fine particles. A forming coating liquid can be applied to the surface of the high refractive index layer 4 and formed by a wet film forming method. Note that at this time, the thickness (d4) of the single layer of the first low refractive index layer 51 is designed to be an optimal value by optical simulation. Furthermore, the thickness (d4) of the first low refractive index layer 51 is preferably within the range of 50 nm to 100 nm, more preferably within the range of 70 nm to 90 nm, in view of its properties as an optical interference layer. Further, the refractive index (n4) of the first low refractive index layer 51 is desirably within the range of 1.30 to 1.40, and more desirably 1.32 to 1.38. If the refractive index (n4) of the first low refractive index layer 51 is as low as possible, it approaches the refractive index of air (refractive index = 1) and it is easier to achieve a low reflectance. Since it is necessary to add a large amount of the material to the coating solution for forming the low refractive index layer, the mechanical strength becomes low and scratches occur easily. On the other hand, if the refractive index (n4) of the first low refractive index layer 51 is 1.40 or more, it is not preferable because the difference in refractive index with air becomes large and the reflectance increases.

The first low refractive index fine particles contained in the first low refractive index layer forming coating liquid are, for example, LiF, MgF, 3NaF.AlF or AlF (all have a refractive index of 1.4), or Na ₃ AlF ₆ (ice). Fine particles made of a low refractive index material such as crystal, refractive index 1.33) can be used. Furthermore, silica particles having voids inside the particles can be suitably used. Silica particles having voids inside the particles can have the refractive index of air (approximately 1.0) in the void portion, and therefore can be made into low refractive index fine particles having an extremely low refractive index. Specifically, porous silica particles and shell-structured silica particles can be used.

The average particle diameter of the first low refractive index fine particles is preferably 1 nm or more and 100 nm or less. When the average particle diameter of the first low refractive index fine particles exceeds 100 nm, light is significantly reflected by Rayleigh scattering, and there is a risk that the first low refractive index layer 51 becomes white and the transparency of the antireflection film 1 decreases. On the other hand, if the average particle diameter of the first low refractive index fine particles is less than 1 nm, problems such as particle non-uniformity in the first low refractive index layer 51 may occur due to particle aggregation.

As the binder matrix forming material for forming the first low refractive index layer 51, an ultraviolet curable material or a thermosetting material can be used. An ionizing radiation curable resin containing a polyfunctional monomer having a (meth)acryloyl group or a monofunctional monomer is used. As the ultraviolet curable material, the acrylic material exemplified as the ultraviolet curable material used for the medium refractive index layer 3 can be used, and as the thermosetting material, for example, organopolysiloxane can be used. The layer consisting of organopolysiloxane is a layer obtained by hydrolysis and dehydration polycondensation using organosiloxane as a starting material according to a wet method, and forms a polymer network with a three-dimensional network structure based on a siloxane (Si-O) skeleton. It is composed of

Note that a solvent and various additives can be added to the first low refractive index layer forming coating liquid for forming the first low refractive index layer 51, if necessary. As the solvent, for example, those exemplified as the solvent used for the medium refractive index layer 3 can be used. Examples of additives include antifoaming agents, leveling agents, antioxidants, ultraviolet absorbers, light stabilizers, polymerization inhibitors, photosensitizers, and the like.

In addition, in the case where an ultraviolet curable material is used as the binder matrix forming material for forming the first low refractive index layer 51 and the first low refractive index layer 51 is formed by irradiating ultraviolet rays, the first low refractive index layer 51 is A photopolymerization initiator is added to the layer-forming coating solution. As the photopolymerization initiator, those exemplified as photopolymerization initiators added to the coating liquid for forming a medium refractive index layer can be used.

As a method for forming the first low refractive index layer 51, it is inexpensive to use a wet film forming method in which a coating liquid for forming the first low refractive index layer is applied to the surface of the high refractive index layer 4. This method is preferable because the antireflection film 1 can be manufactured in this manner.

On the other hand, when forming the low refractive index layer 5 as a two-layer structure, the second low refractive index layer 52 formed has a higher refractive index than the first low refractive index layer 51, and has a higher refractive index than the medium refractive index layer 3 and the film body. This layer has a refractive index lower than that of No. 21. This second low refractive index layer 52 is a layer mainly composed of one or more materials selected from silicon oxide, magnesium fluoride, and lithium fluoride, and is preferably formed using a dry method. According to this dry method, it is generally possible to control the film thickness more precisely than the wet method, and there are advantages such as good adhesion and uniformity of film formation. In particular, when using a wet method, adhesion often depends on the wettability of other layers in contact, and sufficient adhesion may not be obtained depending on the materials of the other layers. However, when a dry method is used, relatively high adhesion can be obtained regardless of the wettability of other layers.

Examples of the material for the second low refractive index layer 52 include silicon oxide, magnesium fluoride, and lithium fluoride, with silicon oxide being particularly preferred. Silicon oxide also exhibits high adhesion to the first low refractive index layer 51, and a lubricant layer 6 is provided on the outermost surface of the second low refractive index layer 52, but silicon oxide is more susceptible to silane coupling than other materials. It is preferable because it exhibits high adhesion to the lubricant layer 6 whose main component is a fluorine-based lubricant having a group. The method for forming the second low refractive index layer 52 is not particularly limited; Although a film process can be used, a sputtering method is particularly preferred from the viewpoint of adhesion.

The refractive index (n5) of the second low refractive index layer 52 is preferably within the range of 1.40 to 1.50. If the refractive index (n5) of the second low refractive index layer 52 is as low as possible, it approaches the refractive index of air (refractive index = 1) and it is easier to achieve a low reflectance, but the characteristics of the second low refractive index layer 52 There are limits to the refractive index of materials suitable for development. On the other hand, if the refractive index (n5) of the second low refractive index layer 52 is 1.50 or more, the difference in refractive index with air becomes large and the reflectance increases, which is not preferable.

Since the second low refractive index layer 52 is formed on the outermost surface of the first refractive index layer 51, it must be thick enough to provide antireflection properties and exhibit scratch resistance. Must be. The thickness of the second low refractive index layer 52 is preferably 10 nm to 50 nm, and preferably within the range of 20 nm to 40 nm, although it is not limited as long as it can provide antireflection properties and scratch resistance. More preferred. Note that when the low refractive index layer 5 has a two-layer structure consisting of the first low refractive index layer 51 and the second low refractive index layer 52, the first low refractive index layer 52, the high refractive index layer 4, and the second low refractive index layer It is preferable that the refractive index layer 51 and the medium refractive index layer 3 are formed so that the film thickness increases in this order.

Here, as described above, when the low refractive index layer 5 is configured as a two-layer structure consisting of the first low refractive index layer 51 and the second low refractive index layer 52, the antireflection film 1 Since the high refractive index layer 4 and the first low refractive index layer 51 are formed by a wet method, and the second low refractive index layer 52 is formed by a dry method, it is possible to improve productivity. Moreover, it becomes possible to reduce manufacturing costs. Further, a lubricant layer 7 is laminated on the surface of the optical adjustment layer, which is formed by laminating the medium refractive index layer 3, the high refractive index layer 4, the first low refractive index layer 51, and the second low refractive index layer 52 in this order. Since the anti-reflection film 1 is constructed by using the anti-reflection film 1, it is possible to exhibit not only extremely excellent anti-reflection properties but also high scratch resistance.

1 Anti-reflection film 2 Transparent base film 21 Film body 22 First hard coat layer 23 Second hard coat layer 3 Medium refractive index layer 4 High refractive index layer 5 Low refractive index layer 51 First low refractive index layer 52 Second low Refractive index layer 6 Lubricant layer

Claims (2)

An antireflection film comprising a transparent base film and an antireflection layer formed on at least one of the transparent base films,
The antireflection layer is configured by laminating a medium refractive index layer, a high refractive index layer, and a low refractive index layer from the transparent base film side,
The medium refractive index layer has a thickness of 85 nm to 150 nm, and a refractive index of 1.55 to 1.60,
The film thickness of the high refractive index layer is 20 nm to 55 nm, and the refractive index is 1.65 to 1.75,
The film thickness of the low refractive index layer is 60 nm to 150 nm, and the refractive index is 1.30 to 1.50,
The visibility reflectance of the antireflection film regarding regular reflection at an incident angle of 5° is 0.6% or less,
The difference between the maximum value and minimum value of reflectance (%) in the wavelength range 450 nm to 750 nm regarding specular reflection at an incident angle of 5° is 0.75 or less,
The difference between the maximum value and minimum value of reflectance (%) in the wavelength range 400 nm to 700 nm regarding specular reflection at an incident angle of 45° is 1.5 or less,
Antireflection, characterized in that the reflection hue is (-1.0≦a*≦1.0, -2.0≦b*≦2.0) over the entire range of incident angles from 35° to 45°. film. The low refractive index layer includes a first low refractive index layer provided on the high refractive index layer side and a second low refractive index layer provided on the first low refractive index layer,
The first low refractive index layer has a thickness of 50 nm to 100 nm, and a refractive index of 1.30 to 1.40,
The antireflection film according to claim 1, wherein the second low refractive index layer has a thickness of 10 nm to 50 nm, and a refractive index higher than that of the first low refractive index layer..

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