JP2007119765A - Coating composition for low refractive index layer and anti-reflection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coating composition for forming a layer with low refractive index, imparting the low refractive index layer with optical transparency, low refractive index and conductivity, and to provide an anti-reflection film with improved productive efficiency, having a conductive low refractive index layer. <P>SOLUTION: The invention relates to the coating composition for low refractive index layer comprising at least conductive low refractive index fine particles composed of low refractive fine particles with a conductive substance adhered on the particles, and a binder component. And to the anti-reflection film having the low refractive index layer composed of fine particles coated with an organic polymeric material and having voids. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a coating composition suitable for obtaining a coating film having both a low refractive index and chargeability, and an antireflection film using a coating film formed using the coating composition.

  A display surface of an image display device such as a liquid crystal display (LCD) or a cathode ray tube display device (CRT) is required to reflect less light emitted from an external light source such as a fluorescent lamp in order to improve its visibility. .

2. Description of the Related Art Conventionally, a phenomenon has been known in which the reflectance is reduced by coating the surface of a transparent object with a transparent film having a low refractive index. Visibility can be improved by providing an antireflection film using such a phenomenon on the display surface of the image display device. The antireflection film has a single layer structure in which a low refractive index layer is provided on the display surface, or one or more intermediate to high refractive index layers are provided on the display surface in order to improve the antireflection performance. There is a multilayer structure in which a low refractive index layer is provided thereon.
The single-layer type antireflection film has a simple layer structure as compared with the multilayer type, and thus has excellent productivity and cost performance. On the other hand, the multilayer type antireflection film can improve the antireflection performance by combining the layer structures, and can easily achieve higher performance than the single layer type.

  In general, the method for forming the low refractive index layer is roughly classified into a vapor phase method and a coating method. Gas phase methods include physical methods such as vacuum deposition and sputtering, and chemical methods such as CVD, and coating methods include roll coating, gravure coating, slide coating, spraying, and immersion. And screen printing.

  On the other hand, in order to prevent reflection on the surface of a substrate such as glass or plastic sheet, it is known to form an antireflection film on the surface, such as magnesium fluoride by vapor deposition or CVD. A film of a low refractive index material is formed on the surface of glass or plastic. However, when the low refractive index layer is formed by such a vapor phase method, it is possible to form a transparent thin film having a high function and a high quality, but it is necessary to precisely control the atmosphere in a high vacuum system. Moreover, since a special heating apparatus or ion generation acceleration apparatus is used, there is a problem that the manufacturing apparatus is complicated and large, and the manufacturing cost is inevitably increased. Further, when the vapor phase method is used, it is difficult to form a transparent thin film having a large area or to form a transparent thin film uniformly on the surface of a film having a complicated shape.

On the other hand, in the case of forming by a spray method among the application methods, there are problems such as poor utilization efficiency of the coating liquid and difficulty in controlling film forming conditions. When using the roll coating method, gravure coating method, slide coating method, dipping method, and screen printing method, etc. The obtained transparent thin film has a problem that its function and quality are inferior to those obtained by the vapor phase method.
As the coating method, a coating solution made of a polymer containing fluorine atoms in the molecule is applied to the surface of the substrate and dried, or the molecule is made of a monomer containing a functional group that is cured by ionizing radiation or heat. It is known that a coating liquid is applied to the surface of a substrate and dried, and then the monomer is cured by UV irradiation or heat to form a low refractive index layer.

Further, as another method for forming the low refractive index layer, there is a method in which the refractive index of the entire coating film is reduced by containing air having a refractive index of 1 inside the coating film.
Patent Document 1 includes an ionizing radiation curable resin composition as such a low refractive index layer, and silica fine particles having an outer shell layer and porous or hollow inside. A low refractive index layer obtained by treating at least a part of the surface of the silica fine particle with a silane coupling agent having a group is disclosed.

On the other hand, the antireflection film may be provided with an antistatic layer having relatively weak conductivity on the display surface in order to prevent the visibility from being deteriorated due to dust attached to the display surface.
Conventionally, in order to impart antistatic properties to an antireflection film, it was necessary to laminate an antistatic layer separately from the low refractive index layer provided on the outermost surface. Examples of such an antireflection film include a structure in which an antistatic layer and a low refractive index layer are provided in this order on a transparent substrate, and further, a hard coat layer, an antiglare layer, a medium refractive index layer, and a high refractive index. Examples include a configuration in which layers and the like are appropriately provided between the transparent substrate and the low refractive index layer (for example, Patent Document 2).

  In order to impart antistatic properties to other functional layers, conductive particles are contained in the hard coat layer, or in a medium refractive index layer or a high refractive index layer having a refractive index of about 1.57 to 2.00. For example, the conductive particles are dispersed, or the inorganic oxide fine particles having a high refractive index per se are imparted with an antistatic property to the high refractive index layer. Since the conductive particles for imparting antistatic properties have a high refractive index, it has been difficult to impart antistatic properties to the low refractive index layer.

  In addition, since the inventor can adjust the refractive index of the transparent particles over a relatively wide range in Patent Document 3, the refractive index of the obtained coating film is also adjusted over a relatively wide range. As a coating composition that can be formed, at least (1) transparent particles obtained by attaching a conductive material having a refractive index different from the core fine particles to the core fine particles, and (2) a binder component are included. A coating composition is disclosed. This patent document also discloses an antistatic antireflection film in which a low refractive index layer is separately provided on a conductive medium refractive index layer.

JP 2005-99778 A JP 2002-254573 A JP 2004-300210 A

The present invention has been accomplished in view of the above-mentioned actual situation, and a first object thereof is a low refractive index layer capable of forming a low refractive index layer having light transmittance, low refractive index property and conductivity. It is to provide a coating composition.
A second object of the present invention is to provide an antireflection film having a low refractive index layer having conductivity and improved production efficiency.

The coating composition for a low refractive index layer according to the present invention contains at least conductive low refractive index fine particles obtained by attaching a conductive substance on low refractive index fine particles, and a binder component.
According to the present invention, by attaching a conductive substance on the low refractive index fine particles, the low refractive index fine particles are imparted with conductivity to become conductive low refractive index fine particles. The low refractive index layer in which is dispersed in the film is imparted with conductivity or antistatic property. Therefore, the low refractive index layer obtained by using the coating composition for a low refractive index layer according to the present invention is a single layer and has the function of an antistatic layer. As a result, there is no need to separately laminate a low refractive index layer and an antistatic layer, so that the number of coating steps can be reduced and the cost can be reduced. In addition, since the low refractive index layer serves as an antistatic layer, when used as an antireflection film or the like, there is an advantage that it is easy to make it thin and transparent.

  In the coating composition for a low refractive index layer according to the present invention, the low refractive index fine particles to which the conductive substance adheres are preferably hollow silica fine particles from the viewpoint of realizing a low refractive index.

  In the coating composition for a low refractive index layer according to the present invention, it is preferable from the viewpoint of transparency that the conductive substance is a metal oxide and / or a conductive polymer.

  In the coating composition for a low refractive index layer according to the present invention, it is preferable that the binder component has ionizing radiation curability from the viewpoint of easily forming a uniform large area coating film and increasing the coating film strength. .

  In the coating composition for a low refractive index layer according to the present invention, it is preferable to further contain a solvent from the viewpoint of forming a uniform coating film by uniformly dissolving or dispersing solid components.

  The antireflection film according to the present invention has conductive low refractive index fine particles obtained by attaching a conductive material on low refractive index fine particles, and a low refractive index layer containing a binder component.

In the antireflection film according to the present invention, the surface resistance value is preferably 1.0 × 10 ¹³ Ω / □ or less from the viewpoint of antistatic properties.

The coating composition for a low refractive index layer according to the present invention can form a low refractive index layer having both light transmittance, low refractive index property and conductivity.
The antireflection film according to the present invention includes a low refractive index layer having conductivity, improves production efficiency, and is obtained at low cost. Furthermore, since the antireflective film according to the present invention also serves as an antistatic layer or the like with one low refractive index layer, it also has the merit of being easily thinned and easily transparent.

The present invention is described in detail below. In the present specification, (meth) acryloyl represents acryloyl and methacryloyl, (meth) acrylate represents acrylate and methacrylate, and (meth) acryl represents acryl and methacryl.
Further, in this specification, “attachment” as referred to with respect to the conductive material means that the conductive material forms a film that at least locally covers the low refractive index fine particles that form the core. In addition, an embodiment in which a conductive material coats the low refractive index fine particles is included. In addition, “having light transmittance” means having a transmittance that can be used as an optical thin film, and the specific degree of transmittance is determined by the performance required for the coating film. Although not limited, generally, if the average visible light transmittance is approximately 70% or more, it can be used as an optical thin film.

I. Coating composition for low refractive index layer The coating composition for low refractive index layer according to the present invention comprises at least conductive low refractive index fine particles obtained by attaching a conductive material on low refractive index fine particles, and a binder component. contains.
According to the present invention, by attaching a conductive substance on the low refractive index fine particles, the low refractive index fine particles are imparted with conductivity to become conductive low refractive index fine particles. The low refractive index layer in which is dispersed in the film is imparted with conductivity or antistatic property. Therefore, the low refractive index layer obtained by using the coating composition for a low refractive index layer according to the present invention is a single layer and has the function of an antistatic layer. As a result, there is no need to separately laminate a low refractive index layer and an antistatic layer, so that the number of coating steps can be reduced and the cost can be reduced. In addition, since the low refractive index layer serves as an antistatic layer, when used as an antireflection film or the like, there is an advantage that it is easy to make it thin and transparent.

  In the conductive low refractive index fine particles, the conductive material is localized on the surface of the conductive low refractive index fine particles, so that a conductive path is easily formed even if the amount of the conductive material contained in the coating film is small. Therefore, the blending ratio of the conductive low refractive index fine particles in the coating composition and the coating film can be increased without impairing the good antistatic property. Therefore, the conductive low refractive index fine particles can provide a desired antistatic property when formed into a coating film even when a relatively small amount of conductive material is used, so the proportion of the low refractive index fine particles can be made relatively high. Thus, a low refractive index layer can be realized even if a conductive material having a high refractive index is included.

[Conductive low refractive index fine particles]
The conductive low refractive index fine particles in the present invention are those obtained by adhering a conductive substance on the low refractive index fine particles. The low refractive index of the low refractive index fine particles is fine particles having a refractive index lower than that of the binder component used in the coating composition.

(Low refractive index fine particles)
The low refractive index fine particles used as the core used in the present invention are fine particles having a refractive index lower than that of the binder component used in the coating composition. The refractive index of the low refractive index fine particles used in the present invention is preferably 1.44 or less, and more preferably 1.40 or less from the viewpoint of imparting low refractive index properties.

Examples of the low refractive index fine particles used in the present invention include fine particles having voids or metal fluoride fine particles having low refractive index.
In the present invention, the fine particles having voids mean fine particles that form a structure in which fine particles are filled with gas and / or a porous structure containing gas. When the gas is air having a refractive index of 1.0, the refractive index decreases in proportion to the occupation ratio in the fine particles as compared with the original refractive index of the fine particles. The present invention also includes fine particles capable of forming a nanoporous structure inside and / or at least part of the surface depending on the form, structure, aggregation state, and dispersion state of the fine particles inside the film. .

  Among the low refractive index fine particles used in the present invention, the fine particles having voids may be either inorganic or organic, and examples thereof include those composed of metals, metal oxides, and resins, preferably silicon oxide ( Silica) fine particles. The silica fine particles may be in a crystalline state, a sol state, a gel state, or the like. The shape of the fine particles may be any of spherical, chain, needle, plate, piece, rod, fiber, and resin.

  Specific examples of the inorganic fine particles having voids include composite oxide sols or hollow silica fine particles disclosed in JP-A Nos. 7-133105 and 2001-233611. Among these, hollow silica fine particles prepared using the technique disclosed in JP-A-2001-233611 are preferable. Since the inorganic fine particles having voids have high hardness, when a low refractive index layer is formed by mixing with a binder, the layer strength is improved, and the refractive index is within a range of about 1.20 to 1.44. It is possible and preferable to prepare.

Specifically, inorganic fine particles having voids such as hollow silica fine particles as described above can be produced by the following first to third steps.
That is, as the first step, an alkali aqueous solution of a silica raw material and an inorganic oxide raw material other than silica is separately prepared in advance, or a mixed aqueous solution of both is prepared. Next, according to the composite ratio of the target composite oxide, the obtained aqueous solution is gradually added to an alkaline aqueous solution having a pH of 10 or more while stirring. Note that, instead of the first step, a dispersion containing seed particles in advance can be used as a starting material.

Next, as a second step, at least a part of elements other than silicon and oxygen is selectively removed from the colloidal particles made of the composite oxide obtained in the above step. Specifically, the elements in the composite oxide are dissolved and removed using a mineral acid or an organic acid, or are contacted with a cation exchange resin and removed by ion exchange.
Subsequently, as the third step, the surface of the colloidal particles is hydrolyzed by adding a hydrolyzable organosilicon compound or silicic acid solution to the colloidal particles of the composite oxide from which some elements have been removed. Cover with a polymer such as a silicon compound or silicic acid solution. In this way, the complex oxide sol described in the above publication can be produced.

  On the other hand, specific examples of the organic fine particles having voids are preferably hollow polymer fine particles prepared by using the technique disclosed in JP-A-2002-80503. Specifically, the hollow polymer fine particle is a heavy polymer obtained from (i) at least one crosslinkable monomer, (ii) an initiator, and (iii) at least one crosslinkable monomer in an aqueous dispersion stabilizer solution. Or a mixture of at least one crosslinkable monomer and at least one monofunctional monomer, and a poorly water-soluble solvent having low compatibility with (i) to (iii). It can be produced by dispersing and performing suspension polymerization. Here, the crosslinkable monomer is one having two or more polymerizable reactive groups, and the monofunctional monomer is one having one polymerizable reactive group.

  The fine particles capable of forming a nanoporous structure inside and / or at least a part of the surface of the membrane are manufactured for the purpose of increasing the specific surface area in addition to the silica fine particles, and the packing column and the porous surface Examples include sustained release materials that adsorb various chemical substances on the part, porous fine particles used for catalyst fixation, or hollow fine particle dispersions and aggregates intended to be incorporated into heat insulating materials and low dielectric materials. . As a specific example, aggregates of porous silica fine particles and silica fine particles manufactured by Nissan Chemical Industries, Ltd. were linked in a chain form from the product names Nippon and Nippon manufactured by Nippon Silica Kogyo Co., Ltd. as commercial products. From the colloidal silica UP series (trade name) having a structure, those within the range of the preferable particle diameter of the present invention can be used.

The refractive index when using fine particles having voids as the low refractive index fine particles in the present invention is 1.20 from the viewpoint that the low refractive index layer can be sufficiently reduced in refractive index and the strength of the fine particles is ensured. 1.44 is preferable, and 1.22-1.40 is more preferable.
In the present invention, the refractive index of the low refractive index fine particles is measured as follows.
On a 80 μm triacetyl cellulose (TAC) substrate, a dispersion of only low refractive index fine particles was applied using a wire bar so that the film thickness was around the wavelength of 550 nm, which is the minimum value of reflectance, and about 100 nm. A coating film of low refractive index fine particles is prepared. The absolute reflectance of the coating film of the low refractive index fine particles is measured using a spectrophotometer (UV-3100PC, manufactured by Shimadzu Corporation). The refractive index of the coating film of the low refractive index fine particles is obtained from the refractive index of the substrate and the obtained reflectance curve, and this is used as the refractive index of the low refractive index fine particles. When obtaining the refractive index of the coating film from the refractive index of the substrate and the obtained reflectance curve, for example, TFCalc Ver. 3.3 simulation software or the like can be used.

  On the other hand, examples of the metal fluoride in the case where metal fluoride fine particles having low refractive index are used as the low refractive index fine particles in the present invention include magnesium fluoride, aluminum fluoride, calcium fluoride, lithium fluoride and the like. . In the present invention, the refractive index when metal fluoride fine particles are used as the low refractive index fine particles is preferably 1.30 to 1.44 from the viewpoint that the low refractive index layer can be sufficiently lowered in refractive index. Preferably it is 1.33-1.40.

Examples of the shape of the low refractive index fine particles used in the present invention include a spherical shape and a needle shape. From the viewpoint of easily forming a conductive path in the coating film, it is preferable to use acicular low refractive index fine particles. If necessary, spherical low refractive index fine particles and acicular low refractive index fine particles can be used in combination.
The average particle size of the spherical low refractive index fine particles is preferably 1 nm or more and 100 nm or less, more preferably the lower limit is 10 nm or more and the upper limit is 50 nm or less. If the average particle diameter of the fine particles exceeds 100 nm, the transparency may be impaired. On the other hand, when the average particle diameter of the fine particles is less than 1 nm, the fine particles may be difficult to disperse. When the average particle diameter of the fine particles is within this range, excellent transparency can be imparted to the low refractive index layer.

  The needle-like low refractive index fine particles have a major axis length of approximately 0.05 to 0.2 μm, a minor axis length of approximately 0.01 to 0.02 μm, and an aspect ratio of approximately 2.5 to 20. Can be preferably used. As the needle-like low refractive index fine particles, the larger the aspect ratio, the easier it is to obtain a conductive path and the better the conductivity. Therefore, when trying to obtain a coating film with better conductivity, the aspect ratio Is preferably closer to 20.

(Conductive substance)
The conductive material is not particularly limited as long as it has conductivity, for example, tin oxide (SnO ₂ ), antimony tin oxide (ATO), indium tin oxide (ITO), antimony oxide (Sb ₂ O ₅ ), conductive metal oxides such as aluminum zinc oxide (AZO), metals such as gold, silver, copper, aluminum, iron, nickel, palladium, platinum, other than polyacetylene, polypyrrole, polythiophene, polyaniline , Conductive polymers such as polyphenylene vinylene, polyacene, or derivatives thereof. Among these, a conductive metal oxide is preferable from the viewpoint of transparency. Moreover, a conductive polymer is also preferably used from the viewpoint of conductivity and transparency.
The conductive material may be locally attached on the low refractive index fine particles, but in order to form a coating film having good conductivity, the low refractive index fine particles are coated over as wide a range as possible. Preferably it is.

(Fine particle surface adhesion treatment with conductive material)
A method for attaching the conductive material to the low refractive index fine particles as the core is not particularly limited. For example, when hollow silica fine particles are taken as an example, the hollow silica fine particles are slurried in an aqueous solution of a metal oxide (for example, ATO). It can be attached by neutralizing, hydrolyzing and baking ATO. The state of adhesion can be adjusted by neutralization hydrolysis conditions (temperature, time, pH) and firing conditions (temperature, time, firing atmosphere).

  Alternatively, in the presence of the low refractive index fine particles as the core, the low refractive index can be obtained by heating a mixture containing a metal carboxylate and an alcohol, or a mixture containing a metal alkoxy group-containing compound and a carboxyl group-containing compound. A method of attaching a metal oxide to the surface of the fine particles (Japanese Patent Laid-Open No. 2004-99358) can be applied.

On the other hand, as methods for attaching or coating the conductive polymer on the low refractive index fine particles, for example, JP-A-2-273407 for polypyrrole and JP-A-3-64369 for polyaniline can be referred to. However, it is not limited to these.
Specifically, for example, a low refractive index fine particle as a core is added to a solvent composed of one or more of water, alcohol, and acetonitrile, and in the presence of a conductive polymer such as pyrrole, an oxidizing agent, and a dopant. It can manufacture by stirring in the temperature range of -30-40 degreeC.
Examples of the oxidizing agent include halogens such as chlorine, bromine and iodine, ferric chloride, boron trifluoride, arsenic pentafluoride, antimony pentafluoride, aluminum chloride and other metal halides, hydrogen peroxide, peracetic acid , Peroxides such as benzoyl peroxide, persulfuric acid and salts thereof, transition metal compounds, protonic acids, and the like, which can be used alone or in combination.
In addition, as the dopant, a commonly used acceptor-type dopant can be used. Specifically, halogen anions such as chlorine, bromine, iodine and hydrogen chloride, halide anions such as hexafluoroline and hexafluoroarsenic, sulfonate anions such as alkylbenzene sulfonic acid, perchlorate anions such as potassium perchlorate, Examples thereof include sulfuric acid anions such as sulfuric acid, and these are used alone or in combination.

  For the adhesion of the conductive material on the low refractive index fine particles, the amount of the conductive material coated on 100 parts by mass of the low refractive index fine particles is preferably in the range of about 5 to 60 parts by mass, more preferably 10 to 60 parts by mass. . If the amount is less than 5 parts by mass, a desired surface resistance value may not be obtained. If the amount exceeds 60 parts by mass, the conductive material has a high refractive index, and thus a desired low refractive index may not be obtained.

[Binder component]
The binder component used together with the above-described low refractive index fine particles is blended as an essential component in order to impart film forming properties and adhesion to the substrate and adjacent layers to the coating composition according to the present invention.
Examples of such a binder component include (i) a reactive binder component that is cured in response to light, heat, and the like, for example, a binder component that is cured in response to electromagnetic waves such as visible light, ultraviolet rays, and electron beams or energy particle beams ( Hereinafter referred to as “photo-curable binder component”), binder component that cures in response to heat (hereinafter referred to as “thermo-curable binder component”), or (ii) without being sensitive to light or heat. Among non-reactive binder components that solidify by drying or cooling, for example, thermoplastic resins, it is possible to use one that has optical transparency when at least solidified or cured to form a coating film.

  Among these binder components, a photocurable binder component, particularly an ionizing radiation curable binder component, can prepare a coating composition excellent in coating suitability, and can easily form a uniform large-area coating film. Moreover, a relatively high-strength coating film can be obtained by curing the binder component in the coating film by photopolymerization after coating.

  As an ionizing radiation curable binder component, a polymerizable functional group that undergoes a reaction that causes a large molecule such as polymerization or dimerization to proceed directly when irradiated with ionizing radiation or indirectly by the action of an initiator. Monomers, oligomers and polymers having the following can be used. In the present invention, radically polymerizable monomers and oligomers having an ethylenically unsaturated bond such as an acrylic group, a vinyl group, and an allyl group can be mainly used, and a photopolymerization initiator is combined as necessary. 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. If necessary, a photocationic initiator is used in combination with the photocationically polymerizable binder component. The binder component is preferably a polyfunctional binder component having two or more polymerizable functional groups in one molecule so that cross-linking occurs between the molecules of the binder component.

  Moreover, in order to improve electroconductivity, it is preferable that it is hydrophilic binders, such as a binder modified with ethylene oxide (henceforth EO modification | denaturation) which makes ion propagation property favorable. Furthermore, it is preferable to use a binder component that leaves a hydroxyl group in the molecule. The hydroxyl group in the binder can improve adhesion to an adjacent layer such as a hard coat layer by hydrogen bonding.

  Monomers and oligomers having an ethylenically unsaturated bond that are preferably used include di (meth) acrylates such as ethylene glycol di (meth) acrylate and pentaerythritol di (meth) acrylate monostearate; trimethylolpropane tri (meth) Acrylate, tri (meth) acrylates such as pentaerythritol tri (meth) acrylate; polyfunctional (meth) acrylates such as pentaerythritol tetra (meth) acrylate and dipentaerythritol penta (meth) acrylate, and these EO-modified products These derivatives, or oligomers obtained by polymerizing the above radical polymerizable monomers can be exemplified.

  In addition to these, epoxy acrylate resins (such as “Epoxy Ester” manufactured by Kyoeisha Chemical Co., Ltd. and “Epoxy” manufactured by Showa High Polymer Co., Ltd.) and urethane acrylate resins obtained by polyaddition of various isocyanates and monomers having hydroxyl groups via urethane bonds ( Oligomers having a number average molecular weight (polystyrene equivalent number average molecular weight measured by GPC method) of 20,000 or less, such as “Shikou” manufactured by Nippon Synthetic Chemical Industry and “urethane acrylate” manufactured by Kyoeisha Chemical Co., Ltd., can also 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” manufactured by Toagosei Co., Ltd., and a copolymer of methyl (meth) acrylate and glycidyl methacrylate is previously polymerized, A reactive polymer having a (meth) acrylate group can be obtained by condensing the glycidyl group of the copolymer and the carboxyl group of (meth) acrylic acid later. By including these components having a high molecular weight, it becomes possible to improve the film formability for complex shapes and to reduce the curling and warping of the antireflection film due to volume shrinkage during curing.

  In addition, ionizing radiation curable binder components are combined with non-reactive polymers and other reactive polymerizable monomers, oligomers and polymers such as thermosetting binder components typified by epoxy resins as binder components. May be. As a binder component which is not reactively curable per se, a non-polymerization reactive transparent resin conventionally used for forming an optical thin film, for example, polyacrylic acid, polymethacrylic acid, polyacrylate, polymethacrylate, Examples thereof include polyolefin, polystyrene, polyamide, polyimide, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, and polycarbonate. As the thermosetting binder component, a monomer having a curing reactive functional group that can be cured by heating to proceed with a large molecular weight reaction such as polymerization or crosslinking between the same functional group or other functional groups by heating, Oligomers and polymers can be used. Specific examples include monomers and oligomers having an alkoxy group, a hydroxyl group, a carboxyl group, an amino group, an epoxy group, a hydrogen bond forming group, and the like.

Moreover, when preparing the coating composition which concerns on this invention, it is preferable to mix | blend a binder component in the ratio of 3-20 mass parts and also 5-10 mass parts with respect to 10 mass parts of electroconductive low refractive index microparticles | fine-particles. .
The conductive low refractive index fine particles and the binder component, which are essential components, have been described above. However, the coating composition according to the present invention preferably contains a solvent or the like in addition to these essential components. Moreover, when using an ionizing radiation-curable binder component as a binder component, it is preferable to contain a photopolymerization initiator.

(solvent)
The solvent is used to dissolve or disperse the solid component, and is not particularly limited. Various solvents, 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 a mixture thereof can be used.
Of these organic solvents, ketone-based organic solvents are preferably used. When a coating composition according to the present invention is prepared using a ketone solvent, the composition can be easily and evenly applied to the substrate surface, and the solvent evaporation rate after coating is moderate and dry. Since unevenness is unlikely to occur, a large-area coating film having a uniform thickness can be easily obtained. As a ketone solvent, it contains a single solvent composed of one kind of ketone, a mixed solvent composed of two or more kinds of ketones, and other solvents together with one or more kinds of ketones, and has lost its properties as a ketone solvent. Those that are not can be used. Preferably, a ketone solvent in which 70% by mass or more, particularly 80% by mass or more of the solvent is occupied by one or more types of ketones is used.

  The amount of the solvent is appropriately adjusted so that each component can be uniformly dissolved and dispersed, does not cause aggregation during storage after preparation, and does not become too dilute during coating. 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 coating composition for a low refractive index layer that is particularly excellent in dispersion stability and suitable for long-term storage can be obtained.

(Photopolymerization initiator)
When the binder component used in the present invention is ionizing radiation curable, it is desirable to use a photopolymerization initiator in order to initiate photopolymerization. As the photopolymerization initiator, a photoradical initiator, a photocationic initiator, or the like is appropriately selected according to the ionizing radiation curable reaction mode of the binder component. The photopolymerization initiator is not particularly limited, and examples thereof include acetophenones, benzophenones, ketals, anthraquinones, disulfide compounds, thiuram compounds, and fluoroamine compounds. 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 also exist 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.

  When using a photoinitiator, it is preferable to mix | blend the said photoinitiator normally in the ratio of 3-8 mass parts with respect to 100 mass parts of ionizing radiation-curable binder components.

(Fluorine-based and / or silicone-based additives)
In the coating composition according to the present invention, the surface of the coating film can be flattened, and it is effective for improving the antifouling property and scratch resistance required for the antireflection film, and imparts slipperiness. Fluorine-based and / or silicone-based additives may be used because they can be used.
Furthermore, it is preferable that at least a part of the fluorine-based and / or silicone-based additive is fixed to the outermost surface of the coating film by forming a covalent bond with the binder component by a chemical reaction. As a result, slipperiness can be stably imparted, and the low refractive index layer formed using the coating composition according to the present invention is necessary after commercialization, and maintains antifouling properties and scratch resistance over a long period of time. be able to.

The fluorine-based additive is a perfluoroalkyl group represented by C _d F _{2d + 1} (d is an integer of ₁ to 21), or — (CF ₂ CF ₂ ) _g — (g is an integer of 1 to 50). Perfluoroalkylene group or F-(— CF (CF ₃ ) CF ₂ O—) _e —CF (CF ₃ ) (where e is an integer of 1 to 50) And CF ₂ = CFCF ₂ CF _2- , (CF ₃ ) ₂ C = C (C ₂ F ₅ )-, and ((CF ₃ ) ₂ CF) ₂ C = C (CF ₃ )- It preferably has a perfluoroalkenyl group.

  If it is a compound containing said functional group, the structure of a fluorine-type additive will not be specifically limited, For example, the polymer of a fluorine-containing monomer or the copolymer of a fluorine-containing monomer and a non-fluorine monomer, etc. are used. You can also. Among them, in particular, a fluorine-containing polymer segment composed of either a homopolymer of a fluorine-containing monomer or a copolymer of a fluorine-containing monomer and a non-fluorine monomer, and a non-fluorine polymer segment, In the case where the block copolymer or graft copolymer comprising the above is repeatedly rubbed, it is difficult for these fluorine-based additives to be removed, and various performances such as antifouling properties can be maintained over a long period of time. Preferably used.

  The fluorine-based additive can be obtained as a commercial product. For example, Nippon Oil & Fats Modiper F series, Dainippon Ink & Chemicals Defensa MCF series and the like are preferably used.

  The fluorine-based and / or silicone-based additive preferably has a structure represented by the following general formula.

（式中、Ｒａはメチル基などの炭素数１〜２０のアルキル基を示し、Ｒｂは非置換、もしくはアミノ基、エポキシ基、カルボキシル基、水酸基、パーフルオロアルキル基、 パーフルオロアルキレン基、パーフルオロアルキルエーテル基、または(メタ)アクリロイル基で置換された炭素数１〜２０のアルキル基、炭素数１〜３のアルコキシ基、またはポリエーテル変性基を示し、各Ｒａ、Ｒｂは互いに同一でも異なっていても良い。また、ｍは０〜２００、ｎは０〜２００の整数である。）

(In the formula, Ra represents an alkyl group having 1 to 20 carbon atoms such as a methyl group, and Rb is unsubstituted, or an amino group, an epoxy group, a carboxyl group, a hydroxyl group, a perfluoroalkyl group, a perfluoroalkylene group, a perfluoro group. An alkyl ether group or an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, or a polyether-modified group substituted with a (meth) acryloyl group, wherein each Ra and Rb are the same or different from each other. M is an integer from 0 to 200, and n is an integer from 0 to 200.)

Polydimethylsilicone having a basic skeleton like the above general formula is generally known to have low surface tension and excellent water repellency and releasability, but various functional groups are introduced into the side chain or terminal. By doing so, a further effect can be provided. For example, reactivity can be imparted by introducing an amino group, epoxy group, carboxyl group, hydroxyl group, (meth) acryloyl group, alkoxy group, etc., and a covalent bond can be formed by a chemical reaction with the ionizing radiation curable binder component. . In addition, by introducing perfluoroalkyl groups, perfluoroalkylene groups, and perfluoroalkyl ether groups, oil resistance and lubricity can be imparted, and by introducing polyether-modified groups, leveling properties and lubricity can be provided. Can be improved.
Such a compound can be obtained as a commercial product. For example, silicone oil FL100 having a fluoroalkyl group (manufactured by Shin-Etsu Chemical Co., Ltd.) or polyether-modified silicone oil TSF4460 (trade name, manufactured by GE Toshiba Silicone Co., Ltd.) Various modified silicone oils can be obtained according to the purpose.

  It is preferable that the said fluorine-type and / or silicone type additive are 0.01-10 mass% in a coating composition, Preferably it is 0.1-3.0 mass% content. If the content is less than 0.01% by mass, sufficient antifouling property and slipperiness cannot be imparted to the antireflection film, and if it exceeds 10% by mass, the strength of the coating film may be extremely reduced. There is.

  These fluorine-based additives and silicone-based additives may be used alone or in combination of two or more depending on the expected effect. By appropriately combining these compounds, various properties such as antifouling property, water and oil repellency, slipping property, scratch resistance, durability, and leveling property can be adjusted to achieve the intended function.

  The coating composition according to the present invention may further contain other components in addition to the components described above. For example, a curing agent, a crosslinking agent, an ultraviolet shielding agent, an ultraviolet absorber, a surface conditioner (leveling agent) and the like can be used as necessary. Further, the coating composition contains low refractive index fine particles to which a conductive substance is attached as an essential component, but may contain low refractive index fine particles to which no conductive substance is attached.

  In order to prepare the coating composition according to the present invention using each of the above components, it may be dispersed according to a general method for preparing a coating solution. For example, each essential component and each desired component are mixed in an arbitrary order, a medium such as beads is added to the obtained mixture, and a dispersion composition is appropriately dispersed with a paint shaker or a bead mill to obtain a coating composition. .

According to the coating composition of the present invention, the refractive index is 1.45 or less when the film thickness is 0.05 to 0.15 μm, and the surface resistivity necessary for preventing dust adhesion is 1.0 × 10 ¹³ Ω. A coating film can be formed that will be / □ or less. 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. Therefore, the coating composition according to the present invention can be suitably used to form a low refractive index layer having antistatic properties such as an antireflection film.

  Moreover, according to the coating composition which concerns on this invention, the haze value prescribed | regulated to JIS-K7361-1 does not change with the haze value only of the base material which apply | coated the coating composition, or the haze value only of the said base material. A coating film with a difference of 1.5% or less can be formed.

2. Antireflection Film The antireflection film according to the present invention has conductive low refractive index fine particles obtained by attaching a conductive material on low refractive index fine particles, and a low refractive index layer containing a binder component.
Since the low refractive index layer contained in the antireflection film according to the present invention contains the conductive low refractive index fine particles described above, a single layer has the functions of a low refractive index layer and an antistatic layer. As a result, since it is not necessary to separately laminate the low refractive index layer and the antistatic layer, the number of coating steps can be reduced, and the cost can be reduced. In addition, since the anti-reflective layer is also used by one low refractive index layer, the antireflection film according to the present invention has an advantage that it is easy to make it thin and transparent.

  The antireflection film according to the present invention includes at least a low refractive index layer containing the conductive low refractive index fine particles, and may be composed of only a single layer of the low refractive index layer. The low refractive index layer may be formed on one or more functional layers and / or the outermost surface on the light-transmitting substrate.

  FIG. 1 schematically shows a cross section of an example of an antireflection film according to the present invention. The antireflective film 1 is provided with a low refractive index layer 3 on one surface side of the light transmissive substrate 2. A hard coat layer 4 is provided between the light transmissive substrate 2 and the low refractive index layer 3. In this embodiment, the light transmission layer is composed of only the low refractive index layer, but another light transmission layer having a different refractive index may be further provided.

The layer structure of the antireflection film according to the present invention is not particularly limited, but specific examples include a single low refractive index layer, base material / low refractive index layer, base material / hard coat layer / low refractive index layer, base Materials / hard coat layer / high refractive index layer / low refractive index layer, substrate / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index layer, and the like. Here, the low refractive index layer is a low refractive index layer comprising the conductive low refractive index fine particles in the present invention.
Hereinafter, the low refractive index layer, which is an essential layer in the present invention, will be described in order.

<Low refractive index layer>
The low refractive index layer includes conductive low refractive index fine particles obtained by attaching a conductive material on low refractive index fine particles and a binder component as essential components, and may be formed of an optional component as necessary.
As the conductive low-refractive-index fine particles, the binder component, and optional components, the same as those described in the coating composition can be used.

In the present invention, the refractive index of the low refractive index layer of the antireflection film can be controlled by the amount of the low refractive index fine particles including the conductive low refractive index fine particles. The refractive index of the low refractive index layer is preferably 1.45 or less, more preferably 1.42 or less. Further, the low refractive index layer preferably satisfies the following formula (I) from the viewpoint of reducing the reflectance.
(M / 4) λ × 0.7 <n ₁ d ₁ <(m / 4) λ × 1.3 Formula (I)
In the formula, m is a positive odd number, n ₁ is the refractive index of the low refractive index layer, and d ₁ is the film thickness (nm) of the low refractive index layer. Further, λ is a wavelength, which is a value in the range of 380 to 780 nm.
In addition, satisfy | filling said numerical formula (I) means that m (positive odd number. Usually 1) which satisfy | fills numerical formula (I) exists in the said wavelength range.
The film thickness of the low refractive index layer is preferably in the range of 15 to 200 nm, more preferably 30 to 150 nm.

[Method of forming low refractive index layer]
The low refractive index layer according to the present invention is preferably formed using the coating composition for low refractive index layer according to the present invention. The coating composition for the low refractive index layer is applied to a light-transmitting substrate or one or more functional layers, dried, and then cured by irradiation with ionizing radiation and / or heating as necessary.
Specific examples of the coating method include various methods such as a spin coating method, a dip method, a spray method, a slide coating method, a bar coating method, a roll coater method, a meniscus coater method, a flexographic printing method, a screen printing method, and a pea coater method. Can be used.

[Physical properties of low refractive index layer]
The low refractive index layer of the antireflection film according to the present invention has a surface resistivity required for dust adhesion prevention of 1.0 × 10 ¹³ Ω / □ or less when the film thickness is 0.05 to 0.15 μm. realizable. 1.0 × 10 ¹³ Ω / □ or less Exceeding 1.0 × 10 ¹² Ω / □ is charged, but the static charge does not accumulate. 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 / Less than □, and most preferably 1.0 × 10 ⁸ Ω / □ or less.

  In addition, the low refractive index layer of the antireflection film according to the present invention preferably has a reflectance that can be lowered to 2.5% or less, more preferably 2.0% or less.

Next, the base material and the functional layer included in the form in which the antireflection film according to the present invention has a plurality of layers instead of the low refractive index layer will be described in order.
<Light transmissive substrate>
The material of the light-transmitting substrate 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, acetate butyrate Examples include films formed of various resins such as cellulose, polyethersulfone, acrylic resin, polyurethane resin, polyester, polycarbonate, polysulfone, polyether, trimethylpentene, polyetherketone, and (meth) acrylonitrile. . The thickness of the substrate is usually about 25 μm to 1000 μm.

<Hard coat layer>
The hard coat layer may be provided on the antireflection film for the purpose of improving performance such as scratch resistance and strength. “Hard coat layer” refers to 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 photopolymerization initiator contained in the ionizing radiation curable resin composition is appropriately selected from those exemplified above and used.
The hard coat layer 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, the film easily breaks against external impacts.
In the present invention, the hard coat layer made of the ionizing radiation curable resin composition may have a function of a medium refractive index layer or a high refractive index layer as described below.

<High refractive index layer and medium refractive index layer>
According to the aspect of the present invention, other refractive index layers (a high refractive index layer and a middle refractive index layer) may be provided in order to further improve the antireflection property.
The refractive index of these refractive index layers can be arbitrarily set within the range of 1.46 to 2.00. In the present invention, the medium refractive index layer has a refractive index higher than at least the low refractive index layer, and means that the refractive index is in the range of 1.46 to 1.80. When used in combination with the middle refractive index layer, it means that the refractive index is at least higher than that of the middle refractive index layer and the refractive index is in the range of 1.65 to 2.00. These refractive index layers may be formed of a binder and ultrafine particles having an average particle diameter of 100 nm or less and having a predetermined refractive index. Specific examples of such fine particles (in parentheses indicate refractive index) include zinc oxide (1.90), titania (2.3 to 2.7), ceria (1.95), tin-doped indium oxide (1 .95 to 2.00), antimony-doped tin oxide (1.75 to 1.85), yttria (1.87), and zirconia (2.10).

  The ultrafine particles preferably have a refractive index higher than that of the binder. Since the refractive index of the refractive index layer is generally determined by the content of ultrafine particles, the refractive index of the refractive index layer increases as the amount of ultrafine particles added increases. Therefore, by adjusting the addition ratio of the binder and the ultrafine particles, it is possible to form a high refractive index layer or a medium refractive index layer having a refractive index in the range of 1.46 to 1.80. It is. If the ultrafine particles have conductivity, the other refractive index layer (high refractive index layer or medium refractive index layer) formed using such ultrafine particles also has antistatic properties. The high refractive index layer or the medium refractive index layer is a vapor deposition film of a high refractive index inorganic oxide such as titania or zirconia formed by a vapor deposition method such as chemical vapor deposition (CVD) or physical vapor deposition (PVD), or A film in which inorganic oxide fine particles having a high refractive index such as titania are dispersed can be obtained.

The film thickness of these other refractive index layers is preferably in the range of 10 to 300 nm, more preferably 30 to 200 nm.
The other refractive index layers (high refractive index layer and medium refractive index layer) may be provided directly on the light transmissive substrate, but a hard coat layer is provided on the light transmissive substrate, and the hard coat layer and the low refractive index are provided. It is preferable to provide between the layers.
In the antireflection film according to the present invention, the haze value defined in JIS-K7361-1 is not different from the haze value of only the base material, no matter what layer is laminated. The difference from the haze value of the base material alone is preferably within 1.5%.

Hereinafter, the present invention will be described more specifically with reference to examples. These descriptions do not limit the present invention. In the examples, “parts” means “parts by mass” unless otherwise specified.
[Evaluation methods]
(1) Refractive index of coating film The refractive index of the coating film was measured using a spectroscopic ellipsometer (UVSEL, manufactured by Joban-Evon: measurement wavelength 633 nm).

(2) Surface resistivity The surface resistivity (Ω / □) was measured using a high resistivity meter (Hiresta UP, manufactured by Mitsubishi Chemical Corporation) at an applied voltage of 100 V for 10 seconds.
(3) Reflectance The reflectance was measured using a spectrophotometer (Shimadzu Corporation, UV-3100PC) equipped with a 5 ° C. regular reflection measuring device. In addition, the reflectance showed the value when it became the minimum value (minimum reflectance) near the wavelength of 550 nm.

<Example 1>
(1) Preparation of coating composition for low refractive index layer The components of the following composition were mixed to prepare a composition for forming a low refractive index layer.
Antimony tin oxide-coated hollow silica fine particle dispersion (average particle size 50 nm, coating amount 30% by mass, solid content 20%, solvent: methyl isobutyl ketone); 14.94 parts by mass EO-modified dipentaerythritol hexaacrylate (DPEA) -12: trade name, manufactured by Nippon Kayaku); 1.99 parts by mass, Irgacure 184 (trade name, manufactured by Ciba Specialty Chemicals); 0.07 parts by mass, TSF4460 (trade name, GE Toshiba Silicone Co., Ltd.) Manufactured: alkyl polyether-modified silicone oil); 0.20 parts by mass / methyl isobutyl ketone; 82.80 parts by mass

(2) Preparation of hard coat layer 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 184 (trade name, manufactured by Ciba Specialty Chemicals); 1.5 parts by mass Methyl isobutyl ketone; 73.5 parts by mass

(3) Preparation of antireflection film Bar coating is applied onto a triacetate cellulose (TAC) film having a thickness of 80 μm, and after removing the solvent by drying, ultraviolet irradiation is performed at an irradiation dose of about 20 mJ / cm ² using an ultraviolet irradiation device. The hard coat layer was cured to obtain a laminated coat film comprising a substrate / hard coat layer having a hard coat layer with a thickness of 10 μm.
On the obtained base material / hard coat layer film, the above-mentioned coating composition for 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., Using a light source H bulb), UV irradiation is performed at an irradiation dose of 200 mJ / cm ² , the coating film is cured, and a low refractive index layer having a film thickness of about 100 nm is formed. An antireflection film of Example 1 comprising a refractive index layer was obtained. With respect to the antireflection film, the surface resistance value and the minimum reflectance were measured by the above methods, and the results are shown in Table 1 below.

<Example 2>
(1) Preparation of coating composition for low refractive index layer The components of the following composition were mixed to prepare a composition for forming a low refractive index layer.
Indium tin oxide-coated hollow silica fine particle dispersion (average particle size 55 nm, coating amount 40% by mass, solid content 20%, solvent: methyl isobutyl ketone); 14.94 parts by mass EO-modified dipentaerythritol hexaacrylate (DPEA) -12: trade name, manufactured by Nippon Kayaku); 1.99 parts by mass, Irgacure 184 (trade name, manufactured by Ciba Specialty Chemicals); 0.07 parts by weight, Modiper FS720 (trade name, manufactured by Nippon Oil & Fats: Silicon) 0.66 parts by mass / methyl isobutyl ketone; 82.33 parts by mass

(2) Preparation of antireflection film An antireflection film was obtained in the same manner as in Example 1, except that the composition obtained in (1) above was used as the coating composition for the low refractive index layer. With respect to the antireflection film, the surface resistance value and the minimum reflectance were measured by the above methods, and the results are shown in Table 1 below.

<Example 3>
(1) Preparation of coating composition for low refractive index layer The components of the following composition were mixed to prepare a composition for forming a low refractive index layer.
・ Polypyrrole-coated hollow silica fine particle dispersion (average particle size 55 nm, coating amount 20 mass%, solid content 20%, solvent: isopropanol); 14.94 mass parts pentaerythritol triacrylate (PET-30: trade name, Nippon Kayaku) 1.99 parts by mass / Irgacure 184 (trade name, manufactured by Ciba Specialty Chemicals); 0.07 parts by mass / Modper FS720 (trade name, manufactured by Nippon Oil & Fats: Silicone additive); 0.66 Parts by mass / isopropanol; 82.33 parts by mass

(2) Preparation of antireflection film An antireflection film was obtained in the same manner as in Example 1, except that the composition obtained in (1) above was used as the coating composition for the low refractive index layer. With respect to the antireflection film, the surface resistance value and the minimum reflectance were measured by the above methods, and the results are shown in Table 1 below.

<Example 4>
(1) Preparation of coating composition for low refractive index layer The components of the following composition were mixed to prepare a composition for forming a low refractive index layer.
Polythiophene-coated hollow silica fine particle dispersion (average particle size 55 nm, coating amount 10% by mass, solid content 20%, solvent: isopropanol); 14.94 parts by mass pentaerythritol hexaacrylate (DPHA: trade name, manufactured by Nippon Kayaku Co., Ltd.) ); 1.99 parts by mass-Irgacure 184 (trade name, manufactured by Ciba Specialty Chemicals); 0.07 parts by mass-Modiper FS720 (trade name, manufactured by Nippon Oil & Fats: silicon-based additive); 0.66 parts by mass・ Isopropanol; 82.33 parts by mass

(2) Preparation of antireflection film An antireflection film was obtained in the same manner as in Example 1, except that the composition obtained in (1) above was used as the coating composition for the low refractive index layer. With respect to the antireflection film, the surface resistance value and the minimum reflectance were measured by the above methods, and the results are shown in Table 1 below.

<Comparative Example 1>
As the low-refractive index fine particles, low-refractive index fine particles to which no conductive substance was attached were used.
(1) Preparation of coating composition for low refractive index layer The components of the following composition were mixed to prepare a composition for forming a low refractive index layer.
Hollow silica fine particle dispersion (manufactured by Catalyst Kasei Kogyo, average particle size 50 nm, solid content 20%, solvent: methyl isobutyl ketone); 14.94 parts by mass Pentaerythritol triacrylate (PET-30: trade name, Nippon Kayaku) 1.99 parts by mass / Irgacure 184 (trade name, manufactured by Ciba Specialty Chemicals); 0.07 parts by mass / Modiper FS720 (trade name, manufactured by Nippon Oil & Fats: Silicone additive); 0.66 mass Parts / methyl isobutyl ketone; 82.33 parts by mass

(2) Preparation of antireflection film An antireflection film was obtained in the same manner as in Example 1, except that the composition obtained in (1) above was used as the coating composition for the low refractive index layer. With respect to the antireflection film, the surface resistance value and the minimum reflectance were measured by the above methods, and the results are shown in Table 1 below. The surface resistance value was 1.0 × 10 ¹⁴ Ω / □ or more.

<Summary of results>
The antireflective film according to the present invention obtained in Examples 1, 2, 3, and 4 using conductive low refractive index fine particles obtained by attaching a conductive material on low refractive index fine particles has a low refractive index, It has been found that the low reflectivity is good, the surface resistance value is in a range where the electrostatic charge is immediately attenuated or not charged, and the antistatic property is also excellent.
On the other hand, in Comparative Example 1 using low refractive index fine particles to which no conductive substance was attached, the low refractive index and low reflectivity were good, but the surface resistance value was 1.0 × 10 ¹⁴ Ω / More than □, it has no antistatic property.

1 schematically illustrates a cross-section of an example of an antireflection film according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Antireflection film 2 Light transmissive base material 3 Low refractive index layer 4 Hard coat layer

Claims (10)

  A coating composition for a low refractive index layer, comprising at least conductive low refractive index fine particles obtained by adhering a conductive material on low refractive index fine particles, and a binder component.   The coating composition for a low refractive index layer according to claim 1, wherein the low refractive index fine particles are hollow silica fine particles.   The coating composition for a low refractive index layer according to claim 1 or 2, wherein the conductive substance is a metal oxide and / or a conductive polymer.   The coating composition for a low refractive index layer according to any one of claims 1 to 3, wherein the binder component has ionizing radiation curability.   The coating composition for a low refractive index layer according to any one of claims 1 to 4, further comprising a solvent.   An antireflection film comprising conductive low-refractive-index fine particles obtained by attaching a conductive material on low-refractive-index fine particles, and a low-refractive index layer containing a binder component.   The antireflection film according to claim 6, wherein the low refractive index fine particles are hollow silica fine particles.   The antireflection film according to claim 6 or 7, wherein the conductive substance is a metal oxide and / or a conductive polymer.   The antireflection film according to claim 6, wherein the binder component has ionizing radiation curability. The antireflection film according to claim 6, wherein the surface resistance value is 1.0 × 10 ¹³ Ω / □ or less.

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