JP2011090301A - Antireflection film including antistatic layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antireflection film including an antistatic layer preventing an increase in hue upon reflection. <P>SOLUTION: The antireflection film is made by forming a hard coat layer including an ionizing radiation-curable resin, an antistatic layer, and a low refractive index layer, in this order on a transparent substrate film. The antistatic layer is formed by using (1) conductive metal oxide, (2) refractive index reducing material containing fluorocarbon resin and/or fine particles having voids, and (3) antistatic layer-forming coating composition containing EO-modified polyfunctional (meth)acrylate as the ionizing radiation-curable resin. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an antireflection film for use on the surface of optical articles such as various displays such as liquid crystal displays and plasma displays, which has antistatic properties that prevent tinting during reflection and prevents dust from adhering. About.

  Display surfaces of optical articles such as liquid crystal displays and plasma displays are required to have low reflection of light emitted from external light sources such as fluorescent lamps in order to improve their visibility. In order to carry out, an antireflection film in which a low refractive index layer having a refractive index lower than the refractive index of the lower layer is formed can be applied to the surface of the optical article directly or through another layer on the transparent substrate film. Has been done. Further, in order to deteriorate the visibility when the surface of the optical article is damaged, it is practiced to impart hard performance to the antireflection film. Further, since optical articles made of plastic are insulative, they are charged by static electricity or the like, and the visibility is deteriorated when dust adheres to the surface. Therefore, it is required to impart antistatic properties to optical articles.

  As an antireflection film having these antistatic properties and hard performance, a hard coat layer is formed on a transparent substrate film, and an antistatic layer containing a metal oxide is formed on the hard coat layer. An antistatic antireflection film in which a low refractive index layer having a lower refractive index than the lower layer is formed as an uppermost layer is known from, for example, Japanese Patent Application Laid-Open No. 2002-267804 (Patent Document 1). In the antireflection film of Patent Document 1, the refractive index of the antistatic layer is in the range of 1.60 to 1.75.

JP 2002-267804 A

  The refractive index of the antistatic layer containing a metal oxide as an antistatic agent is usually about 1.57 to 1.75. In an antireflection film having a laminated structure comprising a transparent base film / hard coat layer / antistatic layer / low refractive index layer (refractive index n = 1.42 or less), the low refractive index layer has a minimum reflectance at a wavelength of 550 nm. When a general low refractive index layer (n = 1.42 or less) is laminated on an antistatic layer having a refractive index of about 1.57 to 1.75, the refractive index of both layers is prepared. Since the difference is large, the reflectance curve becomes V-shaped, the reflectance in the short wavelength region and the long wavelength region is increased in the visible light region, red / blue tint occurs in the antireflection film, and the difference in refractive index increases. There is a problem that the color tone at the time of reflection becomes tight.

1, in the antireflection film of a multilayer structure comprising a transparent substrate film / hard coat layer / antistatic layer / low refractive index layer, the refractive index of the low refractive index layer (n ¹⁾ and 1.37, antistatic When the refractive index (n ² ) of the layer is 1.53, 1.57, 1.61, 1.65, the vertical axis represents the reflectance (%), and the horizontal axis represents the wavelength of light (nm). A reflectance curve is shown. A curve indicated by a solid line in FIG. 1 indicates a reflectance curve of the antireflection film when there is no antistatic layer. According to FIG. 1, the larger the refractive index difference between the antistatic layer and the low refractive index layer, the larger the curve of the V-shaped curve and the higher the reflectance in the short wavelength region and the long wavelength region. It can be seen that the red and blue tints become intense.

  Therefore, the present invention uses a conductive metal oxide having a high refractive index for the antistatic layer of the antireflection film having a laminated structure comprising a transparent base film / hard coat layer / antistatic layer / low refractive index layer. An object of the present invention is to provide an antireflection film having an antistatic layer that prevents tint during reflection.

The antireflection film of the present invention for solving the above-mentioned problems is obtained by forming a hard coat layer containing an ionizing radiation curable resin, an antistatic layer, and a low refractive index layer in this order on a transparent substrate film. The antistatic layer comprises (1) a conductive metal oxide, (2) a fluororesin, and / or a refractive index reducing substance containing fine particles having voids, and (3) ionizing radiation. As curable resins, EO-modified polyfunctional (meth) acrylate (EO-modified ethylene glycol di (meth) acrylate, EO-modified pentaerythritol di (meth) acrylate monostearate, EO-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri) (Meth) acrylate, EO-modified pentaerythritol tetra (meth) acrylate derivative, EO-modified di Selected from pentaerythritol penta (meth) acrylate and EO-modified DPHAE, characterized in that it is formed by using the EO-modified multifunctional (meth) acrylate) for forming an antistatic layer coating composition comprising.

In the antireflection film of the present invention, the reflected hue is 7 or less in absolute value of hue a * defined by JIS-Z-8729 and 6 or less in absolute value of hue b *.

  Hue a * and hue b * are indices in color coordinates defined in JIS-Z-8729 (edited by JIS Handbook 33 “Color-1996”, Japanese Standards Association). According to JIS-Z-8729, the color tone of the measurement object is represented by three values of lightness L, hue a *, and hue b *. It shows that the lightness is so high that the lightness L is large. The hue a * represents redness, and the larger the value, the stronger the redness, and the minus (-) indicates that the redness is insufficient, in other words, the greenness is strong. Further, the hue b * is an index of yellowness, and when this value is large, it indicates that the yellowness is strong, and when it is − (minus), it indicates that the yellowness is insufficient and the color becomes blue. And when both hue a * and hue b * are 0, it means colorlessness.

The antistatic layer of the antireflection film of the present invention contains a conductive metal oxide as an antistatic agent, and has a fluororesin having a refractive index lower than the refractive index of the conductive metal oxide and / or voids. Since the antistatic layer in the antireflection film of the present invention contains a fine particle and is formed of a coating composition containing EO-modified polyfunctional (meth) acrylate as an ionizing radiation curable resin , a conventional conductive metal The refractive index can be adjusted to be lower than that of the antistatic layer formed using a coating composition containing an oxide. For this reason, since the refractive index difference between the antistatic layer and the low refractive index layer can be adjusted, antireflection can be realized, and the absolute value of the hue a * defined by JIS-Z-8729 is 7 or less. Thus, an antireflection film having an antistatic layer adjusted to a refractive index capable of preventing the occurrence of a tint having an absolute value of hue b * of 6 or less can be obtained.

The refractive index (n ¹ ) of the low refractive index layer in the antireflection film having a laminated structure consisting of a transparent substrate film / hard coat layer / antistatic layer / low refractive index layer is 1.37, and the refractive index of the antireflective layer is When (n ² ) is set to 1.53, 1.57, 1.61, and 1.65, a reflectance curve in which the vertical axis represents reflectance (%) and the horizontal axis represents light wavelength (nm) is shown. It is a graph to show. It is a schematic sectional drawing which shows the layer structure of the antireflection film of this invention. 1 schematically shows a cross section of an example of a liquid crystal display device in which a display surface is covered with an antireflection film including the antireflection film of the present invention as a light transmission layer.

DESCRIPTION OF SYMBOLS 1 Transparent base film 2 Hard coat layer 3 Antistatic layer 4 Low refractive index layer 10 Polarizing film 11 Backlight unit 21 Glass substrate 22 Pixel part 23 Black matrix layer 24 Color filter 25 Transparent electrode layer 26 Glass substrate 27 Transparent electrode layer 28 Seal material 29 Alignment film 101 Liquid crystal display device

  FIG. 2 is a schematic cross-sectional view showing the layer structure of the antireflection film of the present invention. In the antireflection film of FIG. 2, a hard coat layer 2 is formed on a transparent substrate film 1, an antistatic layer 3 is further formed thereon, and a low refractive index layer 4 is further formed thereon. ing.

Antistatic Layer The antireflection film of the present invention has a surface resistivity of 1.0 × 10 ¹³ Ω / □ necessary for preventing dust adhesion when the antistatic layer has a thickness of 0.05 to 0.15 μm. The following can be realized. 1.0 × 10 ¹³ Ω / □ to 1.0 × 10 ¹² Ω / □ are charged, but no static charge is accumulated. Preferably, the electrostatic charge is charged, and immediately decaying range ^{1.0 × 10 12 Ω / □ ~1.0} × 10 10 Ω / □, more preferably not charged range 1.0 × ¹⁰ 10 Ω / □ or less, and most preferably 1.0 × 10 ⁸ Ω / □ or less.

Appropriate refractive index of the antistatic layer The appropriate refractive index of the antistatic layer at which the reflection hue by the antireflection film is appropriate depends on the refractive index of the low refractive index layer laminated thereon. Therefore, it is necessary to lower the refractive index layer of the antistatic layer so that the lower the refractive index of the low refractive index layer, the more suitable the reflected hue. For example, when the refractive index of the low refractive index layer is 1.42, the refractive index of the antistatic layer needs to be 1.56 or less.

Type of conductive metal oxide (1) The conductive metal oxide that can be used in the present invention is used as an antistatic agent, for example, tin oxide (SnO ₂ ), antimony tin oxide (ATO), indium tin oxide. Examples thereof include ITO (ITO), antimony oxide (Sb ₂ O ₅ ), and aluminum zinc oxide (AZO).

(2) Shape; particle size The shape of the conductive metal oxide is not particularly limited, and may be spherical, acicular, or flake shaped. The particle size of the conductive metal oxide is preferably 0.01 μm to 0.1 μm. When the particle size exceeds 0.1 μm, the transparency of the antistatic layer is impaired, and when it is less than 0.01 μm, it is difficult to disperse the conductive metal oxide.

The coating composition for forming the fluororesin antistatic layer is not particularly limited as long as it is a polymerizable compound having fluorine in the molecule or a polymer thereof, but the ionizing radiation curable type. Monomers and / or polymers containing the fluorine atom are preferably used. The fluorine atom-containing ionizing radiation curable resin is a binder component having a low refractive index and having film formability (film forming ability). The fluorine atom-containing ionizing radiation curable resin used in the present invention has a functional group that is cured by ionizing radiation (sometimes referred to simply as “ionizing radiation curable group”), or has an ionizing radiation curable group. In addition, since it also has a functional group that can be cured by heat (sometimes referred to simply as “thermosetting group”), a coating solution containing the resin is applied to the surface of the object to be coated and dried. When irradiation with ionizing radiation or irradiation with ionizing radiation and heating are performed, chemical bonds such as cross-linking bonds are formed in the coating film, and the coating film can be cured efficiently.

  The “ionizing radiation curable group” contained in the fluorine atom-containing ionizing radiation curable resin is a functional group capable of curing a coating film by causing a large molecular weight reaction such as polymerization or crosslinking by irradiation with ionizing radiation. There are, for example, those in which the reaction proceeds by a polymerization reaction such as photoradical polymerization, photocationic polymerization, or photoanion polymerization, or a reaction mode such as addition polymerization or condensation that proceeds via photodimerization. Among them, in particular, ethylenically unsaturated bonds such as acrylic group, vinyl group, and allyl group are directly photoradically polymerized by irradiation with ionizing radiation such as ultraviolet rays and electron beams, or indirectly by the action of an initiator. It is preferable because it causes a reaction and is relatively easy to handle including the photocuring step.

  The “thermosetting group” that may be contained in the fluorine atom-containing ionizing radiation curable resin causes a large molecular weight reaction such as polymerization or cross-linking between the same functional groups or other functional groups by heating. Examples of functional groups that can be cured are alkoxy groups, hydroxyl groups, carboxyl groups, amino groups, epoxy groups, and the like.

  Among these functional groups, a hydrogen bond-forming group is preferable because it has excellent affinity with inorganic ultrafine particles and improves the dispersibility of the inorganic ultrafine particles and aggregates thereof in a binder. Among the hydrogen bond-forming groups, particularly hydroxyl groups are easy to introduce into the binder component, and form covalent bonds with hydroxyl groups present on the surface of fine particles having inorganic voids due to the storage stability of the coating composition or heat curing. The fine particles having voids are preferable because they act as a cross-linking agent and can further improve the coating strength.

  In order to sufficiently reduce the refractive index of the coating film, the refractive index of the fluorine atom-containing ionizing radiation curable resin is preferably 1.50 or less.

  Among fluorine atom-containing ionizing radiation curable resins, monomers and / or oligomers containing and / or not containing fluorine atoms in the molecule are highly effective in increasing the cross-linking density of the coating film, and are components with high fluidity due to their low molecular weight. There is also an effect of improving the coating suitability of the coating composition.

  On the other hand, among the fluorine atom-containing ionizing radiation curable resins, the fluorine atom-containing polymer already has a high molecular weight, and therefore has higher film forming properties than fluorine atom-containing and / or non-containing monomers and / or oligomers. When the fluorine atom-containing polymer is combined with the fluorine atom-containing and / or non-containing monomer and / or oligomer, the fluidity is improved, so that the coating suitability can be improved, and the crosslinking density is also increased. The hardness and strength can be improved.

  Examples of the fluorine atom-containing monomer having an ethylenically unsaturated bond include fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluorobutadiene, perfluoro-2,2-dimethyl-1). , 3-dioxole, etc.), a part of acrylic or methacrylic acid and a fully fluorinated alkyl, alkenyl, aryl ester (for example, a compound represented by the following formula 1 or formula 2), a complete or partially fluorinated vinyl ether, Examples thereof include partially fluorinated vinyl esters and fully or partially fluorinated vinyl ketones.

  When combining a fluorine atom-containing polymer having a polymerizable functional group capable of polymerizing with each other and a fluorine atom-containing and / or non-containing monomer, the film-forming property of the coating composition is improved by the fluorine atom-containing polymer, and The contained and / or non-containing monomers are preferable because the crosslinking density and coating suitability are improved, and excellent hardness and strength can be imparted to the coating film by the balance of both components. In this case, by using a combination of a fluorine atom-containing polymer having a number average molecular weight of 20,000 to 500,000 and a fluorine atom-containing and / or non-containing monomer having a number average molecular weight of 20,000 or less, It is preferable because various physical properties including film properties, film hardness, film strength and the like are easily balanced.

  As the polymer containing fluorine in the molecule, a homopolymer or copolymer of one or two or more fluorine atom-containing monomers arbitrarily selected from the fluorine atom-containing monomers as described above, or one or two or more A copolymer of a fluorine atom-containing monomer and one or more fluorine-free monomers can be used.

  Specifically, polytetrafluoroethylene; 4-fluoroethylene-6-fluoropropylene copolymer; 4-fluoroethylene-perfluoroalkyl vinyl ether copolymer; 4-fluoroethylene-ethylene copolymer; polyvinyl fluoride; Polyvinylvinylidene fluoride; polymer or copolymer of a part of acrylic or methacrylic acid and a fully fluorinated alkyl, alkenyl, aryl ester (for example, a compound represented by the following formula 1 or 2); fluoroethylene-carbonization Examples thereof include hydrogen-based vinyl ether copolymers; fluorine-modified products of resins such as epoxy, polyurethane, cellulose, phenol, polyimide, and silicone.

(Wherein R ¹ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a halogen atom. Rf represents a fully or partially fluorinated alkyl group, alkenyl group, heterocycle or aryl group. R ² and R ³ each independently represents a hydrogen atom, an alkyl group, an alkenyl group, a heterocyclic ring, an aryl group or a group defined by the above Rf, wherein R ¹ , R ² , R ³ and Rf each represent a substituent other than a fluorine atom. And any two or more groups of R ² , R ³ and Rf may be bonded to each other to form a ring structure.)

(In the formula, A represents a completely or partially fluorinated n-valent organic group. R ⁴ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a halogen atom. R ⁴ represents a substituent other than a fluorine atom. (N represents an integer of 2 to 8.)
In addition, a commercial product such as a trade name Cytop manufactured by Asahi Glass Co., Ltd. can be exemplified.

  Among them, in particular, the polyvinyl vinylidene fluoride derivative represented by the following general formula 3 has a low refractive index, can introduce a curable functional group, and is excellent in compatibility with other binder components and fine particles having voids. Therefore, it is particularly preferable.

(In the formula, R ⁵ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a halogen atom. R ⁶ represents a direct or fully or partially fluorinated alkyl chain, alkenyl chain, ester chain, or ether chain. And represents a fully or partially fluorinated vinyl group, (meth) acrylate group, epoxy group, oxetane group, aryl group, maleimide group, hydroxyl group, carboxyl group, amino group, amide group, and alkoxy group.)

  Specifically, diacrylates such as pentaerythritol triacrylate, ethylene glycol diacrylate, pentaerythritol diacrylate monostearate; tri (meth) acrylates such as trimethylolpropane triacrylate and pentaerythritol triacrylate, pentaerythritol tetraacrylate derivatives And polyfunctional (meth) acrylates such as dipentaerythritol pentaacrylate, or oligomers obtained by polymerizing these radical polymerizable monomers. These fluorine-free monomers and / or oligomers may be used in combination of two or more.

  Monomer, oligomer, polymer belonging to the above fluorine atom-containing ionizing radiation curable resin, and monomers, oligomers, polymers not belonging to the resin are appropriately combined to form a film, coating suitability, ionizing radiation curing crosslinking density, Various properties such as the content of fluorine atoms and the content of polar groups having thermosetting properties can be adjusted. For example, the crosslinking density and processability are improved by monomers and oligomers, and the film forming property of the coating composition is improved by polymers.

  In the present invention, a monomer having a number average molecular weight (polystyrene equivalent number average molecular weight measured by GPC method) of 20,000 or less and a polymer having a number average molecular weight of 20,000 or more are selected from fluorine atom-containing ionizing radiation curable resins. It is possible to easily adjust various properties of the coating film by appropriately combining them.

Fine particles having voids “ fine particles having voids ” means that the gas is refracted as a result of a structure in which the gas is filled with gas and / or a porous structure containing gas, or as a result of the fine particles forming an aggregate. In the case of air having a refractive index of 1.0, it refers to fine particles and aggregates of which the refractive index has decreased in inverse proportion to the occupancy ratio of air in the fine particles compared to the original refractive index of the fine particles. For example, it is manufactured for the purpose of increasing the specific surface area, and is used as a column for packing, a controlled release material that adsorbs various chemical substances to the porous portion of the surface, porous fine particles used for catalyst fixation, a heat insulating material, Of the hollow fine particles intended to be incorporated into a low dielectric material, those having an average particle diameter in the range of the present invention can be preferably used.

As inorganic porous fine particles, for example, those within the range of particle diameters that can be preferably used in the present invention from the trade names Nipsil and Nipgel manufactured by Nippon Silica Kogyo Co., Ltd. as commercially available products, and as inorganic hollow particles The hollow silica fine particles prepared by using the technique disclosed in JP-A-2001-233611 are preferably used. Typical refractive index of silica is about 1.45, whereas porous or hollow silica has a low refractive index of about 1.20 to 1.44. For example, in a dispersion solution in which seed particles of metal oxide other than SiO ₂ or SiO ₂ are dispersed, a silica raw material and an alkaline aqueous solution of an inorganic oxide raw material other than silica are gradually added, and the seed particles are used as nuclei. , By growing fine particles comprising silica and an inorganic oxide other than silica, and then dissolving or removing elements other than silicon and oxygen in the grown particles, or making the silica particles porous, Hollow silica fine particles can be obtained by a method of coating the surface of the silica particles with a polymer such as a hydrolyzable organic compound or a silicic acid solution.

  Examples of the inorganic fine particles forming the aggregate include aggregates of porous silica fine particles and silica fine particles manufactured by Nissan Chemical Industries, Ltd. from the product names Nippon and Nippon manufactured by Nippon Silica Kogyo Co., Ltd. as commercial products. Among the colloidal silica UP series (trade name) having a chain-like structure, those within the range of the particle diameter that can be preferably used in the present invention can be used. The fine particles having an average particle diameter of 5 nm to 300 nm used in the present invention may be formed by connecting fine particles having a primary particle diameter of 5 nm to 100 nm in a chain.

  The organic fine particles having voids themselves are, for example, porous particles having a polymer layer and a pore-filling layer as shown in JP-A No. 2002-256004, wherein the pore-filling layer is a fugitive substance, Examples thereof include a substitution gas, or a combination thereof, and porous particles having a glass transition temperature of 10 ° C. to 50 ° C. of the polymer layer.

  The organic fine particles forming the aggregate are, for example, commercially available functional fine particle aggregate MP-300F manufactured by Soken Chemical Co., Ltd. (commercially available as 0.1 μm acrylic aggregate particles). Etc. can be preferably used.

  Among the fine particles having voids themselves or forming voids by forming aggregates, the fine particles having voids of inorganic components, particularly silica, are easy to manufacture and hard themselves, Since the film strength when combined is improved, it can be preferably used.

  The primary particle diameter of the fine particles having voids is preferably in the range of an average particle diameter of 5 nm to 300 nm in order to impart excellent transparency to the coating film.

The ionizing radiation curable resin It is essential that the ionizing radiation curable resin contains an EO-modified polyfunctional (meth) acrylate that improves conductivity and improves ion propagation. EO-modified polyfunctional (meth) acrylate is a hydrophilic binder.

Use monomers, oligomers, and polymers that have polymerizable functional groups that cause a reaction that causes polymerization or dimerization to proceed to a large molecule, either directly upon exposure to ionizing radiation or indirectly by the action of an initiator. be able to. Specifically, radically polymerizable monomers and oligomers having an ethylenically unsaturated bond such as an acryl group, a vinyl group, and an allyl group are preferable, and polymerization is performed in one molecule so that cross-linking occurs between molecules of the binder component. It is desirable that it is a polyfunctional binder component having 2 or more, preferably 3 or more functional functional groups. However, other ionizing radiation curable binder components may be used. For example, a photocationically polymerizable monomer or oligomer such as an epoxy group-containing compound may be used . Et al is preferred to use a binder component leaving the hydroxyl groups in the molecule. The hydroxyl group in the binder can improve adhesion to adjacent layers such as a hard coat layer and a low refractive index layer by hydrogen bonding.

  Monomers preferably used in the ionizing radiation curable resin composition include di (meth) acrylates such as ethylene glycol di (meth) acrylate and pentaerythritol di (meth) acrylate monostearate; trimethylolpropane tri ( Tri (meth) acrylates such as (meth) acrylate, pentaerythritol tri (meth) acrylate, polyfunctional (meth) acrylates such as pentaerythritol tetra (meth) acrylate derivatives and dipentaerythritol penta (meth) acrylate, EO Denatured products and the like can be exemplified.

  In addition to these, epoxy acrylate resins (“Epoxy ester” (trade name) manufactured by Kyoeisha Chemical Co., Ltd., “Lipoxy” (trade name) made by Showa High Polymer, etc.), various isocyanates, and monomers having hydroxyl groups are bonded via urethane bonds. Oligomers with a number average molecular weight (polystyrene equivalent number average molecular weight measured by GPC method) of 20,000 or less, such as urethane acrylate resin (“Shikou” manufactured by Nippon Synthetic Chemical Industry and “urethane acrylate” manufactured by Kyoeisha Chemical Co., Ltd.) obtained by polyaddition It can be preferably used.

  These monomers and oligomers are highly effective in increasing the cross-linking density of the coating film, and the number average molecular weight is as small as 20,000 or less, so they are highly fluid components and have the effect of improving the coating suitability of the coating composition. is there.

  Furthermore, if necessary, a reactive polymer having a (meth) acrylate group in the main chain or side chain and having a number average molecular weight of 20,000 or more can be preferably used. These reactive polymers can be purchased as commercial products such as “macromonomer” (trade name) manufactured by Toagosei Co., Ltd., or a copolymer of methyl methacrylate and glycidyl methacrylate is polymerized in advance. Then, a reactive polymer having a (meth) acrylate group can be obtained by condensing the glycidyl group of the copolymer and the carboxyl group of methacrylic acid or acrylic acid. By including these components having a large molecular weight, it becomes possible to improve the film formability for complex shapes and to reduce curling and warping of the antireflection laminate due to volume shrinkage during curing.

  When the binder resin is a photocurable resin, it is desirable to use a photoinitiator to initiate radical polymerization. Although it does not specifically limit to a photoinitiator, For example, acetophenones, benzophenones, ketals, anthraquinones, disulfide compounds, thiuram compounds, fluoroamine compounds, etc. are mentioned. More specifically, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one, benzyldimethylketone, 1- (4-dodecyl) Phenyl) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane Examples thereof include -1-one and benzophenone. Among these, 1-hydroxy-cyclohexyl-phenyl-ketone and 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one are polymerized by irradiation with ionizing radiation even in a small amount. Since it initiates and accelerates the reaction, it is preferably used in the present invention. These can be used either alone or in combination. These are also present in commercial products. For example, 1-hydroxy-cyclohexyl-phenyl-ketone can be obtained from Ciba Specialty Chemicals Co., Ltd. under the trade name Irgacure 184.

In the coating composition for forming the solvent antistatic layer, an organic solvent for dissolving and dispersing the solid component is essential, and the type thereof is not particularly limited. For example, alcohols such as methanol, ethanol and isopropyl alcohol; ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; esters such as ethyl acetate and butyl acetate; halogenated hydrocarbons; aromatic hydrocarbons such as toluene and xylene Or mixtures thereof can be used.

  Among them, it is preferable to use a ketone-based organic solvent. When prepared using a ketone-based solvent, it can be easily and uniformly applied to the surface of the substrate, and the evaporation rate of the solvent after application is moderate. This is because it is difficult to cause uneven drying, and a large-area coating film having a uniform thickness can be easily obtained.

  The amount of the solvent is such that each component can be uniformly dissolved and dispersed, does not cause aggregation during storage after preparation of the coating composition for forming an antistatic layer, and is not too dilute during coating. Adjust as appropriate. Prepare a high-concentration coating composition by reducing the amount of solvent used within the range where this condition is satisfied, store it in a state that does not take up the volume, take out the necessary amount at the time of use, and make the concentration suitable for coating work It is preferred to dilute. When the total amount of the solid content and the solvent is 100 parts by mass, the solvent is 50 to 95.5 parts by mass with respect to the total solids of 0.5 to 50 parts by mass, and more preferably the total solid content is 10 to 30 parts by mass. By using the solvent at a ratio of 70 to 90 parts by mass with respect to parts, a composition for forming an antistatic layer that is particularly excellent in dispersion stability and suitable for long-term storage can be obtained.

Other components Other than the above components of the coating composition for forming the antistatic layer contain a polymerization initiator of an ionizing radiation curable binder component, if necessary. Good. For example, a dispersant, an ultraviolet shielding agent, an ultraviolet absorber, a surface conditioner (leveling agent) and the like can be used as necessary.

Preparation method of coating composition for forming antistatic layer The coating composition for forming an antistatic layer may be an ink already used, an antistatic agent, an ionizing radiation curable binder, a photoinitiator, a solvent, etc. May be prepared in combination. In order to prepare a coating composition for forming an antistatic layer using each of the above components, it may be dispersed according to a general method for preparing a coating solution. For example, if the conductive fine particles are in the form of a colloid, they can be mixed as they are, and if they are in a powder form, a medium such as beads is put into the obtained mixture, and the mixture is appropriately used with a paint shaker or a bead mill. By carrying out the dispersion treatment, a composition for forming an antistatic layer for coating can be obtained.

  Coating compositions for forming an antistatic layer include, for example, spin coating, dip, spray, slide coating, bar coating, roll coater, meniscus coater, flexographic printing, screen printing, bead coater, etc. It can apply | coat on a base material with these various methods. The coated material is usually dried as necessary, and then an antistatic layer is formed by irradiating and curing ionizing radiation such as ultraviolet rays and electron beams.

The material of the transparent substrate film is not particularly limited, and general materials used for the antireflection film can be used. For example, triacetate cellulose (TAC), polyethylene terephthalate (PET), diacetyl cellulose, Examples include films formed of various resins such as acetate butyrate cellulose, polyethersulfone, acrylic resin, polyurethane resin, polyester, polycarbonate, polysulfone, polyether, trimethylpentene, polyetherketone, (meth) acrylonitrile, etc. be able to. The thickness of the substrate is usually about 25 μm to 1000 μm.

Hard coat layer The hard coat layer is formed for the purpose of imparting performance such as scratch resistance and strength to the laminate itself, and is an essential constituent layer in the present invention. In the present invention, the “hard coat layer” means a layer having a hardness of H or higher in a pencil hardness test specified in JIS 5600-5-4: 1999.

  The hard coat layer is preferably formed using an ionizing radiation curable resin composition, and more preferably has a (meth) acrylate-based functional group, such as a relatively low molecular weight polyester resin or polyether resin. , Acrylic resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin, polybutadiene resin, polythiol polyether resin, polyhydric alcohol, ethylene glycol di (meth) acrylate, pentaerythritol di (meth) acrylate monostearate, etc. (Meth) acrylate; tri (meth) acrylate such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate derivative, dipentaerythritol Monomers as polyfunctional compounds such as penta (meth) acrylate, or oligomers such as epoxy acrylate or urethane acrylate can be used.

  The hard coat layer in the antireflection film of the present invention has a thickness after curing of 0.1 to 100 μm, preferably 0.8 to 20 μm. When the film thickness is 0.1 μm or less, sufficient hard coat performance cannot be obtained, and when the film thickness is 100 μm or more, it is not preferable because it easily breaks against an external impact.

Low Refractive Index Layer For the low refractive index layer laminated on the uppermost layer of the antireflection film of the present invention, a known method for forming a generally used low refractive index layer may be used. For example, a coating liquid containing a low refractive index inorganic fine particle such as silica or magnesium fluoride and a binder resin, a coating liquid containing these hollow fine particles and a binder resin, or a coating liquid containing a fluorine-based resin or the like is used. A low refractive index layer can be obtained by forming a coating film or forming a thin film by vapor deposition of low refractive index inorganic fine particles.

Physical Properties of Antireflection Film The antireflection film according to the present invention has a surface resistivity of 1.0 × 10 ¹³ Ω / □ or less when the film thickness of the antistatic layer is 0.05 to 0.15 μm. . Preferably, it is 1.0 × 10 ⁸ Ω / □ or less. The reflection hue is an antireflection film characterized by having an absolute value of hue a * of 7 or less and an absolute value of hue b * of 6 or less as defined in JIS-Z-8729.

Image Display Device The antireflection film of the present invention is particularly suitable for display surfaces of image display devices such as liquid crystal display devices (LCD), cathode ray tube display devices (CRT), plasma display panels (PDP), and electroluminescence displays (ELD). It is suitably used for forming at least one layer of a multilayer antireflection film to be coated, particularly a low refractive index layer.

  FIG. 3 schematically shows a cross section of an example of a liquid crystal display device in which a display surface is covered with a multilayer antireflection film including the antireflection film of the present invention as a light transmission layer. The liquid crystal display device 101 prepares a color filter 24 in which an RGB pixel portion 22 (22R, 22G, 22B) and a black matrix layer 23 are formed on one surface of a glass substrate 21 on the display surface side, and the pixel of the color filter. The transparent electrode layer 25 is provided on the part 22, the transparent electrode layer 27 is provided on one surface of the glass substrate 26 on the backlight side, the glass substrate 26 on the backlight side and the color filter 24, and the transparent electrode layers 25 and 27 are Face each other with a predetermined gap therebetween, adhere with a sealant 28, enclose liquid crystal L in the gap, form an alignment film 29 on the outer surface of the glass substrate 26 on the back side, The polarizing film 10 in which the antireflection film of the present invention is laminated on the outer surface of the glass substrate 21 is pasted, and the backlight unit 11 is arranged behind. That.

  In the following Examples 1 and 2 and Comparative Example 1, regarding the evaluation of the antistatic layer, the measurement of the surface resistivity (Ω / □) of the obtained coating film was conducted using a high resistivity meter (Hiresta UP, Mitsubishi Chemical). The outermost surface of the laminate was measured at an applied voltage of 100V. The reflectance and the reflected hue were measured using a spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC: trade name) equipped with a 5 ° C. regular reflection measuring device. In addition, the reflectance showed the value (minimum reflectance) when it became the minimum value near the wavelength of 550 nm.

[Example 1] When a fluororesin is used as the refractive index reducing substance 1,1,2-trifluoroallyloxy monomer (described below) is used as the fluororesin used in the coating composition for forming an antistatic layer of Example 1. Using a compound (see Formula 5 below) reacted with an aF acryloyl group to give a reactive group to a polymer having a hydroxyl group as a polymer of Formula 4) An antireflection film was obtained. The compound of the following formula 5 had a molecular weight of 150,000 and a hydroxyl group ratio of 15:85.

Preparation of coating composition for forming antistatic layer A coating composition for forming an antistatic layer having a refractive index of 1.53 was prepared by mixing the following components.
Indium tin oxide dispersion (average particle size 0.3 μm, solid component 30%, solvent: methyl isobutyl ketone) 33.3 parts by mass The above fluororesin 6 parts by mass EO-modified DPHA (DPEA-12: trade name, Nippon Kayaku) 4 parts by mass Irgacure 184 (trade name, manufactured by Ciba Specialty Chemicals) 0.5 parts by mass Methyl isobutyl ketone 90.3 parts by mass

Preparation of Hard Coat Layer Forming Coating Composition A component having the following composition was blended to prepare a hard coat layer forming coating composition.
Pentaerythritol triacrylate (PETA) 30.0 parts by mass Irgacure 907 (trade name, manufactured by Ciba Specialty Chemicals) 1.5 parts by mass Methyl isobutyl ketone 73.5 parts by mass

Preparation of coating composition for forming a low refractive index layer A coating composition for forming a low refractive index layer having a refractive index of 1.37 was prepared by blending the components of the following composition.
Silica sol having voids (20% methyl isobutyl ketone solution) 12.85 parts by mass Pentaerythritol triacrylate (PETA) 1.43 parts by mass Irgacure 907 (trade name, manufactured by Ciba Specialty Chemicals) 0.1 part by mass TSF4460 (trade name) GE Toshiba Silicone Co., Ltd .: alkyl polyether-modified silicone oil) 0.12 parts by weight Methyl isobutyl ketone 85.5 parts by weight

Preparation of antireflection film (base film / hard coat layer / antistatic layer / low refractive index layer) The above coating composition for forming a hard coat is bar-coated on a triacetate cellulose (TAC) film having a thickness of 80 μm and dried. After removing the solvent, ultraviolet irradiation was performed using an ultraviolet irradiation device at an irradiation dose of 20 mJ / cm ² to cure the coating film, and a hard coat layer having a thickness of about 5 μm was produced.

The obtained antistatic layer-forming coating composition is bar-coated on the obtained laminate of the base film / hard coat layer and dried to remove the solvent, and then an ultraviolet irradiation device (Fusion UV System Japan ( Using a light source H bulb (manufactured by Co., Ltd.), an ultraviolet ray was irradiated at an irradiation dose of 50 mJ / cm ² to cure the coating film to produce an antistatic layer having a thickness of about 90 nm.

On the resulting laminate comprising the base film / hard coat layer / antistatic layer, the coating composition for forming a low refractive index layer is bar-coated and dried to remove the solvent, and then an ultraviolet irradiation device. (Fusion UV System Japan Co., Ltd., light source H bulb) is used to irradiate ultraviolet rays at an irradiation dose of 200 mJ / cm ² , cure the coating film, and produce a low refractive index layer having a thickness of about 100 nm. The antireflection film of Example 1 was obtained. Table 1 below shows the results of measuring the minimum reflectance, reflection hue, and surface resistance of the antireflection film of Example 1 based on the above methods.

[Example 2] When porous silica is used as the refractive index reducing substance
Preparation of coating composition for forming antistatic layer The following composition was mixed to prepare a coating composition for forming an antistatic layer having a refractive index of 1.51.
Indium tin oxide dispersion (average particle size 0.3 μm, solid component 30%, solvent: methyl isobutyl ketone) 33.3 parts by mass Silica sol having voids (20% methyl isobutyl ketone solution) 25 parts by mass EO-modified DPHA (DPEA) -12: Trade name, manufactured by Nippon Kayaku Co., Ltd.) 3.75 parts by mass Irgacure 184 (trade name, manufactured by Ciba Specialty Chemicals) 0.19 parts by mass Methyl isobutyl ketone 64.01 parts by mass

Preparation of antireflection film (base film / hard coat layer / antistatic layer / low refractive index layer) A coating composition for forming a hard coat having the same composition as in Example 1 on a triacetate cellulose (TAC) film having a thickness of 80 μm. Was applied under the same conditions.
On the obtained laminate of the base film / hard coat layer, the above antistatic layer forming coating composition was coated, dried and cured under the same conditions as in Example 1, and the film thickness was about 90 nm. An antistatic layer was prepared.

  On the laminate comprising the obtained base film / hard coat layer / antistatic layer, a low refractive index composition having the same composition as in Example 1 was applied, dried and cured under the same conditions, and the film thickness was An antireflective film of Example 2 was obtained by producing a low refractive index layer of about 100 nm. Table 1 below shows the results of measuring the minimum reflectance, the reflection hue, and the surface resistance value of the antireflection film of Example 2 based on the above methods.

[Comparative Example 1] When no refractive index reducing substance is used
Preparation of antistatic layer-forming coating composition The following components were mixed to prepare an antistatic layer-forming coating composition having a refractive index of 1.60.
Indium tin oxide dispersion (average particle size 0.3 μm, solid component 30%, solvent: methyl isobutyl ketone) 33.3 parts by mass PETA (PET-30: trade name, manufactured by Nippon Kayaku) 10 parts by mass Irgacure 184 ( (Product name, manufactured by Ciba Specialty Chemicals) 0.5 parts by mass 90.3 parts by mass of methyl isobutyl ketone

Preparation of antireflection film (base film / hard coat layer / antistatic layer / low refractive index layer) On a triacetate cellulose (TAC) film having a thickness of 80 μm, a hard coat composition having the same composition as in Example 1 was subjected to the same conditions. It was produced in.

  The above-mentioned coating composition for forming an antistatic layer is coated, dried and cured under the same conditions as in Example 1 on the obtained laminate of the base film / hard coat layer, and has a film thickness of about 85 nm. An antistatic layer was prepared.

  On the obtained base film / hard coat layer / antistatic layer film, a low refractive index composition having the same composition as in Example 1 was applied, dried and cured under the same conditions, and the film thickness was about 100 nm. A low refractive index layer was produced to obtain the antireflection film of Comparative Example 1. Table 1 below shows the results of measuring the minimum reflectance, reflection hue, and surface resistance value of the antireflection film of Comparative Example 1 based on the above method.

  According to Table 1, it can be seen that, in both Examples 1 and 2, with respect to the reflected hue, the hue a * is an absolute value of 7 or less and the hue b * is an absolute value of 6 or less. . In addition, since the minimum reflectance and the surface resistance value are in a good range, it is excellent as an antistatic antireflection film.

  In the present invention, the antireflection film in which the antistatic layer is formed using the coating composition for forming an antistatic layer can prevent dust from adhering to it, and can also prevent the color at the time of reflection. It is useful as an antireflection film to be attached to the surface of an optical article such as a display.

Claims (4)

An antireflection film formed by forming a hard coat layer containing an ionizing radiation curable resin, an antistatic layer, and a low refractive index layer in this order on a transparent substrate film,
The antistatic layer is
(1) conductive metal oxide,
(2) Refractive index-reducing substance containing fluororesin and / or fine particles having voids,
(3) EO-modified polyfunctional (meth) acrylate (EO-modified ethylene glycol di (meth) acrylate, EO-modified pentaerythritol di (meth) acrylate monostearate, EO-modified trimethylolpropane tri (meth)) as ionizing radiation curable resin EO-modified polyfunctional (meth) acrylate selected from acrylate, pentaerythritol tri (meth) acrylate, EO-modified pentaerythritol tetra (meth) acrylate derivative, EO-modified dipentaerythritol penta (meth) acrylate and EO-modified DPHAE) An antireflection film formed using the coating composition for forming an antistatic layer. The antireflection film according to claim 1, wherein the EO-modified polyfunctional (meth) acrylate is EO-modified DPHA. The refractive index of the low refractive index layer is 1.37 or more and 1.42 or less, and the refractive index of the antistatic layer is 1.51 or more and 1.56 or less, the hard coat layer, the antistatic layer, 2. The antireflection film according to claim 1, wherein all the layers of the low refractive index layer are cured by ultraviolet irradiation using a coating composition containing an ionizing radiation curable resin. The image display apparatus which has the antireflection film of Claim 1, 2, or 3 on the surface of a display.

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