JP3776979B2 - Antireflection film and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes various types of displays such as word processors, computers, televisions, plasma display panels, the surfaces of polarizing plates used in liquid crystal display devices, sunglasses lenses made of transparent plastics, prescription eyeglass lenses, optical lenses such as finder lenses for cameras, The present invention relates to an antireflection film excellent in antireflection on the surfaces of various instrument covers, window glasses of automobiles, trains, etc., and a method for producing the same.
[0002]
[Prior art]
Conventionally, transparent substrates such as glass and plastic have been used for displays such as curved mirrors, rearview mirrors, goggles, window glass, personal computers, word processors, plasma displays, and other various commercial displays. When observing visual information such as objects, characters, figures, etc., or when observing an image from a reflective layer through a transparent substrate with a mirror, the surface of these transparent substrates is reflected by external light and the internal visual information is visible. There was a problem that it was difficult.
[0003]
As a method for preventing reflection of such a transparent substrate, conventionally, a method of applying an antireflection coating on the surface of glass or plastic, a hard coat layer as necessary on the surface of a transparent substrate such as a glass / plastic substrate, etc. There is a method of forming a thin film such as MgF ₂ or SiO _{2 with} a film thickness of about 0.1 μm through a vapor phase method such as vapor deposition, sputtering, or plasma CVD.
[0004]
[Problems to be solved by the invention]
Although the functional thin film manufacturing method by the vapor phase method can obtain a high-performance and high-quality thin film, it requires precise control of the atmosphere in a high vacuum system, and is also capable of special heating or ionization. There is a problem that the production cost is inevitably increased because the generation accelerating device is required and the manufacturing apparatus is complicated and large. There is also a problem that it is difficult to increase the area of the thin film or to manufacture a complicated shape.
On the other hand, among the production methods of functional thin films by the coating method, those using the spray method have problems such as poor utilization efficiency of the coating liquid and difficulty in controlling the film forming conditions.
In addition, the method for producing a functional thin film using a coating method such as a dipping method or a screen printing method has good utilization efficiency of the film forming raw material, and is advantageous in terms of mass production and equipment cost. There is a problem that the functional thin film is inferior in function and quality as compared with a thin film obtained by a vapor phase method.
[0005]
In recent years, as a method for obtaining an excellent quality thin film by a coating method, a method in which a dispersion liquid in which inorganic or organic ultrafine particles are dispersed in an acidic and / or alkaline aqueous solution is coated on a substrate and baked has been proposed. According to this manufacturing method, it is advantageous in terms of mass production and equipment costs, but since a high-temperature baking process is required during the manufacturing process, it is impossible to form a film on a plastic substrate. The uniformity of the film is not sufficient due to the difference in the degree of shrinkage between the coating film and the coating film, and the performance is still inferior when compared with the thin film obtained by the vapor phase method. Or more) and has the disadvantage of being inferior in productivity.
Accordingly, an object of the present invention is to provide a high-function and high-quality antireflection film by a coating method advantageous in terms of mass production and equipment cost.
[0006]
[Means for Solving the Problems]
The above object is achieved by the present invention described below. That is, the present invention provides an antireflective film in which a hard coat layer, a high refractive index layer and a low refractive index layer are laminated directly or via another layer on a transparent substrate film, wherein the low refractive index layer comprises _{R m Si (OR') n (} R and R'represents an alkyl group having 1 to 10 carbon atoms, m + n is 4, respectively m and n are integers) the presence of acetic acid a silicon alkoxide represented by A reflection characterized by comprising a SiO ₂ gel layer formed from a SiO ₂ sol solution prepared by hydrolysis underneath and having a SiO ₂ concentration of 0.1 to 10% by mass with addition of sodium acetate or lithium acetate A prevention film and a method for producing the same.
[0007]
According to the present invention, lower silicon alkoxide is hydrolyzed in the presence of acetic acid to prepare several nanometer fine particles by sol-gel method , and sodium acetate or lithium acetate in which the ultra fine particles are dispersed is added. The applied sol solution is applied on the high refractive index layer formed on the hard coat layer on the surface of the transparent base film, and then heat-treated at a temperature lower than the heat deformation temperature of the transparent base film or irradiated with active energy rays. By forming the SiO ₂ gel layer, a low refractive index layer having substantially the same performance as that of the low refractive index layer obtained by the vapor phase method can be obtained, and the thermal deformation temperature is low as in a plastic substrate. Even if the base material is used, it is possible to form a high-function and high-quality antireflection film.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in more detail with reference to embodiments.
FIG. 1 is a diagram schematically showing a cross section of an example of the antireflection film of the present invention. The antireflection film of this example is an example in which a hard coat layer 2, a high bitterness layer 3 and a low refractive index layer 4 are laminated on a transparent base film 1, and reference numeral 5 in the figure is laminated as necessary. An adhesive layer or primer layer.
[0009]
In the present invention, the transparent base film may be any film as long as it is transparent, for example, a triacetyl cellulose film, a diacetyl cellulose film, an acetate butyrate cellulose film, a polyether sulfone film, a poly Acrylic resin films, polyurethane resin films, polyester films, polycarbonate films, polysulfone films, polyether films, trimethylpentene films, polyetherketone films, (meth) acrylonitrile films, etc. can be used. An axially stretched polyester is preferably used because it is excellent in transparency and heat resistance and has no optical anisotropy. The thickness is preferably about 8 μm to 1,000 μm.
[0010]
The hard coat layer and the high refractive index layer formed on the surface of the transparent base film are formed from a thermosetting resin or an ionizing radiation curable resin, but the transparent base film is made of a thermoplastic resin. It is preferable to use an ionizing radiation curable resin that does not require a high temperature during curing. In the present specification, “hard coat layer” or “having a hard property” means a material having a hardness of H or higher in a pencil hardness test shown in JIS K5400. In the present invention, “high refractive index” and “low refractive index” refer to the relative refractive index between adjacent layers.
[0011]
The ionizing radiation curable resin suitable for forming the hard coat layer and the high refractive index layer is preferably one having an acrylate-based functional group, for example, a relatively low molecular weight polyester resin, polyether resin, acrylic resin. , Epoxy resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, oligomers or prepolymers such as (meth) acrylates of polyfunctional compounds such as polyhydric alcohols, and ethyl (meta) as a reactive diluent ) Acrylate, ethylhexyl (meth) acrylate, monofunctional monomers such as styrene, methylstyrene, N-vinylpyrrolidone, and polyfunctional monomers such as trimethylolpropane tri (meth) acrylate, hexanediol (meth) acrylate, tri Lopylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) ) Those containing a relatively large amount of acrylate or the like can be used.
Further, in order to convert the ionizing radiation curable resin into an ultraviolet curable resin, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, tetramethylthiuram monosulfide are used as photopolymerization initiators. In addition, thioxanthones, and n-butylamine, triethylamine, tri-n-butylphosphine, etc. can be mixed and used as a photosensitizer.
[0012]
When the hard coat layer and the high refractive index layer are formed of the above ionizing radiation curable resin alone, if the crosslinking density becomes too high at the time of curing, the flexibility is lowered, and the hard coating layer is bent when the resulting antireflection film is bent. In some cases, a crack or the like is likely to enter the layer or the high refractive index layer.
In this case, the non-reactive resin is preferably mixed with the hard coat layer and the high refractive index layer forming composition in an amount up to about 50% by weight in the entire composition. When there is too much addition amount of non-reactive resin, the hardness of the layer obtained may become inadequate. As this non-reactive resin, a thermoplastic resin is mainly used. In particular, when a mixture of polyester acrylate and polyurethane acrylate is used as the ionizing radiation curable resin, poly (methyl methacrylate) or poly (butyl methacrylate) can keep the coating film high in the thermoplastic resin used. it can. Moreover, in this case, since the refractive index is close to that of the main ionizing radiation curable resin, the transparency of the coating film is not impaired, and it is advantageous in terms of transparency, in particular, low haze value, high transmittance, and compatibility. .
[0013]
The refractive index of the hard coat layer and the high refractive index layer comprising the above components is usually about 1.49 to 1.51. In the example shown in FIG. 1, in order to make the hard coat layer and the high refractive index layer have a high refractive index, a metal or metal oxide having a high refractive index is contained in the resin composition for forming the hard coat layer and the high refractive index layer. It is preferable to improve the refractive index of the hard coat layer and the high refractive index layer to be about 1.50 to 2.30 by adding ultrafine particles. Examples of materials that improve the refractive index of the hard coat layer and the high refractive index layer include ZnO (refractive index 1.90), TiO ₂ (refractive index 2.3 to 2.7), and CeO ₂ (refractive index 1. 95), Sb ₂ O ₅ (refractive index 1.71), SnO ₂ , ITO (refractive index 1.95), Y ₂ O ₃ (refractive index 1.87), La ₂ O ₃ (refractive index 1.95). , ZrO ₂ (refractive index 2.05), Al ₂ O ₃ (refractive index 1.63), etc.
Further, in order to further improve the refractive index of the hard coat layer and the high refractive index layer, a resin containing molecules and atoms of the high refractive index component is used in the resin composition for forming the hard coat layer and the high refractive index layer. May be. Examples of the molecules and atoms of the component for improving the refractive index include halogen atoms other than F, S, N, P atoms, aromatic rings, and the like.
[0014]
The hard coat layer and the high refractive index layer composed of the above components are prepared by dissolving or dispersing the above components in an appropriate solvent to form a coating solution, and applying the coating solution directly to the substrate film and curing it. Alternatively, it may be formed by applying to a release film and curing, and then transferring it to the transparent substrate film using an appropriate adhesive. The thickness of the hard coat layer is usually preferably about 3 to 10 μm.
For curing the hard coat layer and the high refractive index layer, an ordinary method of curing an ionizing radiation curable resin, that is, a method of curing by irradiation with electron beams or ultraviolet rays can be used. For example, in the case of electron beam curing, 50 to 1000 KeV emitted from various electron beam accelerators such as a Cockloft Walton type, a bandegraph type, a resonant transformation type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type, Preferably, an electron beam or the like having an energy of 100 to 300 KeV is used. In the case of ultraviolet curing, ultraviolet rays emitted from light beams such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, and a metal halide lamp can be used. .
[0015]
Next, by forming a low refractive index layer made of a SiO ₂ gel film having a refractive index of 1.38 to 1.46 from the SiO ₂ sol solution on the surface of the high refractive index layer, the present invention shown in FIG. An antireflection film is obtained.
The SiO ₂ sol can be prepared by dissolving silicon alkoxide in an organic solvent suitable for coating and adding a certain amount of water to perform hydrolysis. A preferred example of the silicon alkoxide used for forming the SiO ₂ sol is a compound represented by R _m Si (OR ′) _n , where R and R ′ represent an alkyl group having 1 to 10 carbon atoms, and m + n Is 4, and m and n are each integers. More specifically, tetramethoxysilane, tetraethoxysilane, tetra-iso-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxysilane, tetra Pentaethoxysilane, tetrapenta-iso-propoxysilane, tetrapenta-n-propoxysilane, tetrapenta-n-butoxysilane, tetrapenta-sec-butoxysilane, tetrapenta-tert-butoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyl Tripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethylethoxysilane, dimethylmethoxysilane, dimethylpropoxysilane, Methyl-butoxy silane, methyl dimethoxy silane, methyl diethoxy silane, hexyl trimethoxy silane and the like.
[0016]
The silicon alkoxide is hydrolyzed by dissolving the silicon alkoxide in a suitable solvent. Examples of the solvent used include alcohols such as methyl ethyl ketone, isopropyl alcohol, methanol, ethanol, methyl isobutyl ketone, ethyl acetate and butyl acetate, ketones, esters, halogenated hydrocarbons, aromatic hydrocarbons such as toluene and xylene, Or the mixture of these is mentioned.
The alkoxide is dissolved in the solvent so as to be 0.1% by weight or more, preferably 0.1 to 10% by weight in terms of SiO ₂ generated when the alkoxide is 100% hydrolyzed and condensed. If the concentration of the SiO ₂ sol is less than 0.1% by weight, the formed sol film cannot sufficiently exhibit the desired characteristics, while if it exceeds 10% by weight, it becomes difficult to form a transparent homogeneous film. Moreover, in this invention, if it is less than the above solid content, it is also possible to use an organic substance and an inorganic binder together.
[0017]
Water more than the amount necessary for hydrolysis is added to this solution, and stirring is performed at a temperature of 15 to 35 ° C., preferably 22 to 28 ° C., for 0.5 to 10 hours, preferably 2 to 5 hours.
In the hydrolysis, catalyst using acetic acid as a medium, the acid to about 0.001～20.0N, preferably added as an aqueous solution of about 0.005～5.0N, hydrolysis water in the aqueous solution It can be moisture for decomposition.
The SiO ₂ sol obtained as described above is a colorless and transparent liquid, is a stable solution having a pot life of about 1 month, has good wettability with respect to the high refractive index layer, and is excellent in coating suitability. ing.
[0018]
Various additives can be added to the sol solution. As the additives, a curing agent can be mentioned to promote film formation, as these curing agents, sodium acetate, lithium and the like. The concentration of the organic solvent solution is about 0.01 to 0.1% by weight, and the amount added to the sol solution is about 0.1 as the above acetate with respect to 100 parts by weight of SiO ₂ present in the sol solution. A range of about 1 part by weight is preferred.
[0019]
Furthermore, although the gel film finally obtained becomes a low refractive index layer of the antireflection film, it may be necessary to adjust the refractive index. For example, a fluorine-based organic silicon compound can be added to lower the refractive index, an organic silicon compound can be added to increase the refractive index, and a boron-based organic compound can be added to further increase the refractive index. Specifically, tetraethoxysilane, tetramethoxysilane, tetrapropoxysilane, tetrabutoxysilane, alkyltrialkoxysilane, Colcoat 40 (manufactured by Colcoat), MS51 (manufactured by Mitsubishi Chemical), Snowtex (manufactured by Nissan Chemical), etc. Organosilicon compounds, ZAFLON FC-110, 220, 250 (manufactured by Toa Gosei Chemical), Sexual Coat A-402B (manufactured by Central Glass), heptadecafluorodecyltrimethoxysilane, tridecafluorooctyltrimethoxysilane, trifluoropropyltrimethoxy Examples thereof include fluorine compounds such as silane, and boron compounds such as triethyl borate, trimethyl borate, tripropyl borate, and tributyl borate. These additives may be added during the preparation of the sol, or may be added after the formation of the sol. By using these additives, a more uniform and transparent sol solution can be obtained by reacting with a silanol group during or after the hydrolysis of silicon alkoxide, and the refractive index of the gel film to be formed is within a certain range. Can be changed.
[0020]
A method of forming a low refractive index layer using the aforementioned SiO ₂ sol solution, the SiO ₂ sol solution to the surface of the high refractive index layer was applied using a coating method, the active energy then coated material A SiO ₂ gel film can be formed by performing a beam irradiation treatment or a heat treatment, and the adhesion of the gel film to the high refractive index layer is remarkably improved. The thickness of the low refractive index layer thus formed is usually preferably in the range of about 50 to 300 nm.
Examples of the method for applying the SiO ₂ sol solution to the high refractive index layer include spin coating, dipping, spraying, roll coating, meniscus coating, flexographic printing, screen printing, and bead coating. .
[0021]
The heat treatment of the coating layer performed after the application of the sol solution is performed at a temperature equal to or lower than the thermal deformation temperature of the transparent base film. For example, when the transparent substrate film is a polyethylene terephthalate film (PET), a silica gel film can be formed by heat treatment at a temperature of about 80 to 150 ° C. for about 1 minute to 1 hour. Such heat treatment conditions vary depending on the type and thickness of the transparent substrate film to be used, and may be determined according to the type of transparent substrate film to be used.
[0022]
Examples of the active energy rays used for curing after the application of the sol solution include electron beams and ultraviolet rays. Particularly, the same electron beams are preferable when used for curing the hard coat layer and the high refractive index layer.
The heat treatment and electron beam irradiation are preferably performed while substituting air with oxygen or in a sufficient oxygen atmosphere. By performing in an oxygen atmosphere, generation of SiO ₂ , polymerization / condensation is promoted, and more uniform and A high quality gel layer can be formed.
[0023]
As an example of the formation of the high refractive index layer, the high refractive index layer is a lower metal alkoxide R _m Ti (OR ′) _n (R and R ′ represent an alkyl group having 1 to 10 carbon atoms, and m + n is 4. M and n are each an integer) or R _m Ta (OR ′) _n (R and R ′ represent an alkyl group having 1 to 10 carbon atoms, m + n is 5, and m and n are each an integer. It can be formed from a metal oxide sol prepared by hydrolysis of a metal alkoxide represented by (A).
[0024]
Examples of the lower metal alkoxide include titanium tetraethoxide, titanium tetra-i-propoxide, titanium tetra-n-propoxide, titanium tetra-n-butoxide, titanium tetra-sec-butoxide, titanium tetra-tert-butoxide. Tantalum pentaethoxide, tantalum penta-i-propoxide, tantalum penta-n-propoxide, tantalum penta-n-butoxide, tantalum penta-sec-butoxide, tantalum penta-tert-butoxide, and the like.
[0025]
The metal alkoxide is hydrolyzed by dissolving the metal alkoxide in a suitable solvent. Examples of the solvent used include alcohols such as methyl ethyl ketone, isopropyl alcohol, methanol, ethanol, methyl isobutyl ketone, ethyl acetate and butyl acetate, ketones, esters, halogenated hydrocarbons, aromatic hydrocarbons such as toluene and xylene, Or the mixture of these is mentioned.
The metal alkoxide is dissolved in the solvent so that the metal alkoxide is 0.1% or more, preferably 0.1 to 10% by weight in terms of metal oxide generated as a result of 100% hydrolysis and condensation of the metal alkoxide. If the concentration of the metal oxide sol is less than 0.1% by weight, the formed functional film cannot sufficiently exhibit the desired characteristics, while if it exceeds 10% by weight, it becomes difficult to form a transparent homogeneous film.
In addition, by changing the metal oxide gel concentration within the above range, the refractive index of the gel film obtained can be adjusted in proportion to the gel concentration. Moreover, in this invention, if it is less than the above solid content, it is also possible to use an organic substance and an inorganic binder together.
[0026]
Water more than the amount necessary for hydrolysis is added to the metal alkoxide solution, and the mixture is stirred at a temperature of 15 to 35 ° C, preferably 22 to 28 ° C, for 5 to 30 hours, preferably 12 to 16 hours. In the hydrolysis, it is preferable to use a catalyst. As these catalysts, acids such as hydrochloric acid, nitric acid, sulfuric acid, formic acid and acetic acid are preferable, and these acids are contained in about 0.1 to 20.0 N, preferably 0. It can be added as an aqueous solution of about 0.5 to 7.0 N, and water in the aqueous solution can be used as water for hydrolysis.
By changing the concentration of the catalyst within the above range during hydrolysis, the refractive index of the gel film obtained can be adjusted in proportion to the concentration of the catalyst.
[0027]
The metal oxide sol obtained as described above is a colorless and transparent liquid, is a stable solution having a pot life of about 1 month, has good wettability with respect to the hard coat layer, and has excellent coating suitability. ing. The metal oxide sol is applied to the surface of the hard coat layer using a coating method. Examples of the method for applying the metal oxide sol to the hard coat layer include spin coating, dipping, spraying, roll coater, meniscus coater, flexographic printing, screen printing, and bead coater.
[0028]
Then, a metal oxide gel film is formed by subjecting the coated material to a heat treatment and / or an active energy ray irradiation treatment. The heat treatment of the coating layer performed after coating the sol solution is performed at a temperature equal to or lower than the thermal deformation temperature of the transparent base film, as in the case of the SiO ₂ sol solution. Further, as the active energy ray used for curing after applying the sol solution, an electron beam is preferable when used for curing the hard coat layer. The electron beam irradiation is preferably performed while substituting air with oxygen or in a sufficient oxygen atmosphere. By performing the irradiation in an oxygen atmosphere, formation of metal oxide, polymerization and condensation are promoted, resulting in a more uniform and high quality. The gel layer can be formed. Next, a low refractive index layer made of SiO ₂ gel is formed as before, and the antireflection film of the present invention is obtained.
[0029]
The antireflection film of the present invention can be further provided with layers for imparting various functions in addition to the above-described layers. For example, an adhesive layer or a primer layer can be provided in order to improve the adhesion between the transparent substrate film and the hard coat layer, or a plurality of hard coat layers can be provided in order to improve the hard performance. As described above, the refractive index of the other layer provided between the transparent base film and the hard coat layer is preferably set to an intermediate value between the refractive index of the transparent base film and the refractive index of the hard coat layer.
[0030]
The other layer may be formed by applying a desired coating solution directly or indirectly on the transparent base film as described above, or by applying a hard coat on the transparent base film. When the layer is formed by transfer, it is formed by applying a coating solution for forming another layer on the hard coat layer formed in advance on the release film, and then the transparent base film and the release film The other layer may be transferred to the transparent substrate film by laminating the film with the release film coating surface facing inward, and then peeling the release film. Further, an adhesive may be applied to the lower surface of the antireflection film of the present invention, and this antireflection film can be used by being attached to an object to be antireflection, for example, a polarizing element.
The antireflection film of the present invention obtained as described above is used for various displays such as word processors, computers, televisions, plasma display panels, the surfaces of polarizing plates used in liquid crystal display devices, sunglasses lenses made of transparent plastics, and prescription glasses. It is useful for preventing reflection of surfaces such as lenses, optical lenses such as camera finder lenses, covers of various instruments, window glass of automobiles, trains and the like.
[0031]
【Example】
Next, the present invention will be described more specifically with reference to examples and comparative examples.
Example 1
MTEOS is dissolved in methyl ethyl ketone as a solvent so that the solid content concentration becomes 3% by weight when it is assumed that methyltriethoxysilane (MTEOS) is ideally hydrolyzed and condensed to SiO ₂ or MeSiO _1.5. The mixture was stirred for 30 minutes until the temperature was stabilized at 25 ° C. (Liquid A).
In the liquid A, hydrochloric acid having a concentration of 0.005N as a catalyst was added in an equimolar amount with the alkoxide group of MTEOS, and hydrolysis was performed at 25 ° C. for 3 hours (liquid B). A mixture of sodium acetate and acetic acid as a curing agent was added to this B liquid, and stirred at 25 ° C. for 1 hour to obtain a SiO ₂ sol solution.
[0032]
An ionizing radiation curable resin (X-12-2400: trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) on a PET film (Lumirror T-60: trade name, manufactured by Diafoil Co., Ltd., thickness 50 μm) having a smooth surface. And ZrO ₂ ultrafine particles (No. 926: trade name, manufactured by Sumitomo Osaka Cement Co., Ltd., refractive index: 1.9) in a weight ratio of 15: 1, a fine particle dispersion is slit-reverse-coated so as to be 0.1 μm / dry. The film was cured by irradiating an electron beam with an acceleration voltage of 175 kV for 5 Mrad to form a high refractive index layer. On this high refractive index layer, an ionizing radiation curable resin (X-12-2400) is applied by gravure reverse coating so as to be 7 μm / dry, and an electron beam is irradiated at an acceleration voltage of 175 KeV for 5 Mrad to cure the coating film. To form a hard coat layer. A two-component curable adhesive (LX660, KW75 (curing agent)) was applied on the hard coat layer by gravure reverse coating to form an adhesive layer.
[0033]
Next, a PET film (A-4300: trade name, manufactured by Toyobo Co., Ltd., 100 μm thick) is laminated through this adhesive layer, and after aging at 40 ° C. for 4 days, the PET film (T-60) is peeled off. Then, the hard coat layer and the high refractive index layer were transferred onto a PET film (A-4300).
On the high refractive index layer on the obtained PET film (A-4300), the above-mentioned SiO ₂ sol solution was further applied so that the film thickness was 0.1 μm / dry, and the coating was performed at 120 ° C. for 1 hour. Heat treatment was performed to obtain the antireflection film of the present invention.
The obtained antireflection film had a total light transmittance of 94.5%, a haze value of 0.5, and a minimum reflectance in the visible light wavelength region of 0.2, and was excellent in antireflection properties. Moreover, the surface pencil hardness was 3H and it was excellent also in hard property.
[0034]
Example 2
Tetrabutoxytitanium _{(Ti (OC 4 H 9)} 4) are formed so that the solid content concentration of 3% by weight when it is assumed that ideally combined hydrolysis and condensation to _{TiO 2, (Ti (OC 4} H 9) ₄ ) was dissolved in ethyl cellosolve as a solvent and stirred for 30 minutes until the liquid temperature was stabilized at 25 ° C. (liquid C).
In solution C, 3N hydrochloric acid as a catalyst was added in a 2.5-fold molar amount with respect to the alkoxide group of (Ti (OC ₄ H ₉ ) ₄ ), and hydrolyzed at 25 ° C. for 3 hours to obtain a TiO ₂ sol solution. Got.
[0035]
A PET film (Lumirror T-60) having a thickness of 50 μm was prepared as a transparent substrate film. On the other hand, the TiO ₂ sol solution was applied on the PET film by gravure reverse coating so that the film thickness after drying was 0.1 μm / dry, and heat-treated at 120 ° C. for 1 hour to obtain a high refractive index layer. (Refractive index 1.9) was formed. On this high refractive index layer, a hard coat resin (PPZ-N-2000: trade name, manufactured by Osaka Kyoei Chemical Co., Ltd.) was applied by gravure reverse coating so as to be 7 μm / dry, and the electron beam was 5 Mrad at an acceleration voltage of 175 KeV. The coating film was cured by irradiation to form a hard coat layer.
[0036]
A two-component curable adhesive (LX660, KW75 (curing agent): trade name, manufactured by Dainippon Ink & Chemicals, Inc.) was applied on the hard coat layer by gravure reverse coating to form an adhesive layer. Next, a PET film (A-4300) is laminated through this adhesive layer, and after aging at 40 ° C. for 4 days, the PET film (T-60) is peeled off, and a hard coat layer and a high refractive index layer are peeled off. Was transferred onto a PET film (A-4300).
The SiO ₂ sol solution of Example 1 was formed on the high refractive index layer on the obtained PET film (A-4300) so as to have a film thickness of 0.1 μm / dry, and the antireflection film of the present invention was formed. Obtained.
The obtained antireflection film had a total light transmittance of 94.5% and a haze value of 0.4, and was excellent in antireflection properties. Moreover, the surface pencil hardness was 3H and it was excellent also in hard property.
[0037]
Comparative Example 1
An antireflection film was produced in the same manner as in Example 1 except that a SiOx film was formed as a low refractive index layer by vacuum deposition. This antireflection film had a total light transmittance of 93.8% and a haze value of 0.7, and the antireflection properties were inferior to those of the above examples. The surface pencil hardness was 2H.
[0038]
Comparative Example 2
An antireflection film was produced in the same manner as in Example 2 except that a SiOx film was formed as a low refractive index layer by vacuum deposition. This antireflection film had a total light transmittance of 94.0% and a haze value of 0.5, and the antireflection properties were inferior to those of the above examples. The surface pencil hardness was 2H.
[0039]
【The invention's effect】
As described above, according to the present invention, lower silicon alkoxide is hydrolyzed, fine particles of several nanometers are prepared by a sol-gel method, and a sol solution in which the ultrafine particles are dispersed is obtained from a transparent substrate film. After applying to the high refractive index layer formed on the hard coat layer on the surface, heat treatment is performed at a temperature lower than the thermal deformation temperature of the transparent substrate film, or irradiation with active energy rays to form a SiO ₂ gel layer A low refractive index layer having almost the same performance as that of a low refractive index layer obtained by a vapor phase method can be obtained, and even if a base material having a low thermal deformation temperature such as a plastic base material is used, it has high functionality. In addition, it is possible to form a high-quality antireflection film.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a cross section of an example of an antireflection film of the present invention.
[Explanation of symbols]
1: Transparent base film 2: Hard coat layer 3: High refractive index layer 4: Low refractive index layer 5: Adhesive layer

Claims (7)

In the antireflective film in which a hard coat layer, a high refractive index layer and a low refractive index layer are laminated directly or via another layer on a transparent substrate film, the low refractive index layer comprises R _m Si (OR ′ ) _N (R and R ′ represent an alkyl group having 1 to 10 carbon atoms, m + n is 4, m and n are each an integer), and hydrolyzing a silicon alkoxide in the presence of acetic acid. An antireflection film comprising an SiO ₂ gel layer formed from an SiO ₂ sol solution prepared and added with sodium acetate or lithium acetate and having an SiO ₂ concentration of 0.1 to 10% by mass .   2. The antireflection film according to claim 1, wherein the low refractive index layer has a refractive index of 1.38 to 1.46. The high refractive index layer is a lower metal alkoxide R _m Ti (OR ′) _n (R and R ′ each represents an alkyl group having 0 to 10 carbon atoms, m + n is 4, and m and n are each an integer) Or hydrolyzing a metal alkoxide represented by R _m Ta (OR ′) _n (R and R ′ represent an alkyl group having 0 to 10 carbon atoms, m + n is 5, and m and n are each an integer) The antireflection film according to claim 1, which is a metal oxide gel layer comprising a metal oxide sol prepared as described above.   2. The antireflection film according to claim 1, wherein the high refractive index layer has a refractive index of 1.50 to 2.30. In the method for producing an antireflective film comprising laminating a hard coat layer, a high refractive index layer and a low refractive index layer directly or via another layer on a transparent substrate film, the low refractive index layer is made of R _m In the presence of acetic acid, a silicon alkoxide represented by Si (OR ′) _n (R and R ′ represent an alkyl group having 1 to 10 carbon atoms, m + n is 4, and m and n are each an integer). was hydrolyzed to prepare a SiO ₂ sol solution SiO ₂ concentration with the addition of sodium acetate or lithium acetate is 0.1 to 10 wt%, applied directly or via another layer on the surface of the transparent substrate film And forming the SiO ₂ gel layer by heat treatment or ionizing radiation irradiation of the formed coating layer.   The method for producing an antireflection film according to claim 5, wherein the refractive index of the low refractive index layer is 1.38 to 1.46. Lower metal alkoxide R _m Ti (OR ′) _n (R and R ′ each represents an alkyl group having 0 to 10 carbon atoms, m + n is 4, m and n are each an integer) Or hydrolyzing a metal alkoxide represented by R _m Ta (OR ′) _n (R and R ′ represent an alkyl group having 0 to 10 carbon atoms, m + n is 5, and m and n are each an integer) The method for producing an antireflection film according to claim 5, wherein the metal oxide sol is formed from a metal oxide sol prepared as described above.

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