JP2000075105A - Antireflection film and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect the surface of a low-refractive index layer without increasing the refractive index of this layer and to improve the flaw resistance thereof by laminating an over-coating layer contg. a fluorine-contained compd. on the low-refractive index layer and specifying the ratio at which the material of the over-coating layer occupies the gaps of the low-refractive index layer to a specific value or below. SOLUTION: A transparent base and the low-refractive index layer 2 having a refractive index lower than the refractive index of this transparent base and a void volume of 3 to 50 vol.% are laminated and the over-coating layer 3 contg. the fluorine-contained compd. is further laminated on the low-refractive index layer 2. The ratio at which the material of the over-coating layer 3 occupies the gaps 23 of the low-refractive index layer 2 is <70 vol.%. The low-refractive index layer 2 contains particulates 21 and a binder 22. The over- coating layer 3 consists of a fluorine-contained polymer of, for example, a weight average mol.wt. of >=20000 and covers the ruggedness on the surface of the low-refractive index layer 2 but does not infiltrate the internal gaps 23. Then, the gaps 23 of the low-refractive index layer 2 are maintained even after the formation of the over-coating layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an antireflection film in which a transparent support, a low refractive index layer and an overcoat layer are laminated in this order, and an image display device using the same.

[0002]

2. Description of the Related Art An antireflection film is used for a liquid crystal display (LC).
D), a plasma display panel (PDP), an electroluminescence display (ELD), and a cathode ray tube display (CRT). As the antireflection film, a multilayer film in which a transparent thin film of a metal oxide is laminated has conventionally been commonly used.
The reason for using a plurality of transparent thin films is to prevent reflection of light of various wavelengths. The transparent thin film of a metal oxide is formed by a chemical vapor deposition (CVD) method or a physical vapor deposition (PVD) method, in particular, a vacuum vapor deposition method which is a kind of the physical vapor deposition method. Although a transparent thin film of a metal oxide has excellent optical properties as an antireflection film, the method of forming by vapor deposition has low productivity and is not suitable for mass production. Instead of the vapor deposition method, there has been proposed a method of producing an antireflection film by forming an optically functional layer on a transparent support by coating.

For the antireflection function, it is necessary to provide a layer having a lower refractive index than the transparent support (low refractive index layer). When a plurality of optically functional layers are provided on the transparent support, the low refractive index layer is provided on the side farthest from the transparent support. In order to lower the refractive index of the coating layer, it is effective to introduce a void in the low refractive index layer. The refractive index of air is 1.00, and the layer containing air in the air gap has a very low refractive index. A method has been proposed in which fine particles are contained in a low refractive index layer to form a gap between or within the fine particles. Japanese Patent Publication No. 60-59250 discloses an antireflection layer having fine pores and particulate inorganic substances. The antireflection layer is formed by coating. The micropores are formed by performing an activation gas treatment after the application of the layer, and the gas is released from the layer.

Japanese Patent Application Laid-Open No. 2-245702 discloses an antireflection film in which two or more kinds of ultrafine particles (for example, MgF ₂ and SiO ₂ ) are mixed and the mixing ratio is changed in the thickness direction. I have. The refractive index is changed by changing the mixing ratio, and the same optical properties as those of the antireflection film provided with the high refractive index layer and the low refractive index layer are obtained. The ultrafine particles are bonded by SiO ₂ generated by thermal decomposition of ethyl silicate. In the thermal decomposition of ethyl silicate, carbon dioxide and water vapor are also generated by burning the ethyl portion. As shown in FIG. 1 of the publication, a gap is formed between the ultrafine particles due to the separation of carbon dioxide and water vapor from the layer. JP-A-7-48527 discloses an antireflection film containing a binder and an inorganic fine powder made of porous silica. Japanese Patent Application Laid-Open No. 9-288201 discloses an antireflection film having a low refractive index layer in which voids are formed between fine particles by stacking two or more fine particles made of a fluoropolymer.

[0005]

The low refractive index layer having a void is characterized in that a very low refractive index can be obtained by air in the void. On the other hand, the low refractive index layer is provided on the side farthest from the transparent support, that is, on the surface side of the antireflection film. Therefore, the surface of the low refractive index layer is easily stained and easily scratched. The antireflection function of the low refractive index layer decreases due to dirt and scratches. In order to protect the surface side layer from dirt and improve scratch resistance, a measure to provide an overcoat layer containing a fluorine-containing compound on the surface side layer,
It is generally well known, not limited to the technical field of antireflection films. However, as a result of research conducted by the present inventors, when an overcoat layer containing a fluorine-containing compound is to be provided on a low-refractive-index layer having a void, the coating solution for the overcoat layer penetrates into the void of the low-refractive-index layer. As a result, the problem that the porosity of the low-refractive-index layer was reduced was recognized. If the porosity of the low refractive index layer decreases, the refractive index of the low refractive index layer increases. An object of the present invention is to provide an antireflection film in which the surface of the low refractive index layer is protected from dirt and the scratch resistance is improved without increasing the refractive index of the low refractive index layer.

[0006]

The object of the present invention has been attained by the following antireflection films (1) to (8) and the following image display device (9). (1) An antireflection film in which a transparent support and a low refractive index layer having a refractive index lower than the refractive index of the transparent support and a porosity of 3 to 50% by volume are laminated, wherein the low refractive index layer An overcoat layer containing a fluorine-containing compound is further laminated thereon, and the ratio of the material of the overcoat layer occupying the voids in the low refractive index layer is less than 70% by volume. film. (2) The antireflection film according to (1), wherein the overcoat layer contains fine particles of a fluorine-containing compound having a particle size of 10 nm or more. (3) The antireflection film according to (1), wherein the coating amount of the overcoat layer is 80% by volume or less of the void amount of the low refractive index layer.

(4) The fluorine-containing compound has a weight average molecular weight of 2
The antireflection film according to (1), wherein the antireflection film is 10,000 or more fluoropolymers. (5) The antireflection film according to (1) or (4), wherein the fluorine-containing compound is a fluorine-containing polymer, and the fluorine-containing polymer is crosslinked after forming the overcoat layer. (6) The antireflection film according to (5), wherein the fluoropolymer is crosslinked by irradiation with radiation. (7) The antireflection film according to (1), wherein the low refractive index layer contains fine particles, and voids are formed between or within the fine particles. (8) The antireflection film according to (1), wherein a high refractive index layer having a refractive index higher than that of the transparent support is provided between the transparent support and the low refractive index layer. (9) An antireflection film in which a transparent support and a low refractive index layer having a lower refractive index than the transparent support and a porosity of 3 to 50% by volume are laminated in this order on the image display surface. An overcoat layer containing a fluorine-containing compound is further laminated on the low refractive index layer, and the ratio of the material of the overcoat layer occupying the voids in the low refractive index layer is less than 70% by volume. An image display device characterized by the above-mentioned. In the present specification, the voids and the porosity of the low refractive index layer mean the voids including the portion occupied by the material of the overcoat layer and the ratio thereof.

[0008]

According to the study of the present inventors, even if an overcoat layer containing a fluorine-containing compound is provided on a low refractive index layer having a void, the material of the overcoat layer occupies the void in the low refractive index layer. It has been found that it is possible to make the ratio of less than 70% by volume. First, if the fluorine-containing compound in the overcoat layer is fine particles of a fluorine-containing compound having a particle size of 10 nm or more, the fine particles close the opening of the void, and the void in the low refractive index layer is maintained. . Second, the gap in the low refractive index layer can be maintained by adjusting the amount of the overcoat layer to be 80% by volume or less of the gap in the low refractive index layer. Third, by setting the weight-average molecular weight of the fluoropolymer in the overcoat layer to 20,000 or more, twice the radius of gyration (Rg) of the polymer in the solution becomes equal to or larger than the size of the voids. Since the diffusion does not occur, the gap in the low refractive index layer is maintained.
As a result, in the antireflection film of the present invention, the surface of the low refractive index layer is protected from dirt and the scratch resistance is improved without increasing the refractive index of the low refractive index layer. By using such an antireflection film, reflection of light on the image display surface of the image display device can be effectively prevented.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure of an antireflection film according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing a main layer configuration of the antireflection film. The embodiment shown in FIG. 1A has a layer structure in the order of a transparent support (1), a low refractive index layer (3), and an overcoat layer (3).
The transparent support (1) and the low refractive index layer (2) have a refractive index satisfying the following relationship. The refractive index of the low-refractive-index layer <the refractive index of the transparent support The embodiment shown in FIG. It has a layer configuration in the order of layer (3).
The relationship between the refractive index of the transparent support (1) and the refractive index of the low refractive index layer (2) is the same as in the above (a). In the embodiment shown in FIG. 1C, the order of the transparent support (1), the hard coat layer (4), the high refractive index layer (5), the low refractive index layer (2), and the overcoat layer (3) is as follows. Having the following layer configuration. Transparent support (1),
The high refractive index layer (5) and the low refractive index layer (2) have a refractive index satisfying the following relationship. The refractive index of the low-refractive-index layer <the refractive index of the transparent support <the refractive index of the high-refractive-index layer In the embodiment shown in FIG. 1 (d), the transparent support (1), the hard coat layer (4), the medium refractive index It has a layer structure of a layer (6), a high refractive index layer (5), a low refractive index layer (2), and an overcoat layer (3) in this order. Transparent support (1), medium refractive index layer (6),
The high refractive index layer (5) and the low refractive index layer (2) have a refractive index satisfying the following relationship. Refractive index of low refractive index layer <Refractive index of transparent support <Refractive index of medium refractive index layer <Refractive index of high refractive index layer FIG. 2 shows cross sections of the low refractive index layer and the overcoat layer in a preferred embodiment of the present invention. It is a schematic diagram. The low refractive index layer (2) shown in FIG. 2 includes fine particles (21) and a binder (22). And, a gap (2) between the fine particles (21).
3) is formed. The void may be present inside the fine particles. The overcoat layer (3) has a particle size of 10
Including fine particles (31) of a fluorine-containing compound having a diameter of at least nm. Since the openings of the voids (23) of the low refractive index layer (2) are closed by the fine particles (31) of the fluorine-containing compound, the voids of the low refractive index layer (2) remain even after the formation of the overcoat layer (3). (23) is maintained.

FIG. 3 is a schematic sectional view of a low refractive index layer and an overcoat layer according to another preferred embodiment of the present invention.
The low refractive index layer (2) shown in FIG. 3 also contains fine particles (21) and a binder (22). And a void (23) is formed between the fine particles (21). The coating amount of the overcoat layer (3) is adjusted to 80% by volume or less of the void (23) of the low refractive index layer (2). In other words, the applied amount of the overcoat layer (3) is adjusted to an amount that adheres to the surface of the low refractive index layer (3). Therefore, the amount of the coating liquid for the overcoat layer (3) penetrating into the voids (23) of the low-refractive-index layer (2) is small. The air gap (23) is maintained. FIG. 4 is a schematic sectional view of a low refractive index layer and an overcoat layer according to another preferred embodiment of the present invention. Also in FIG. 4, the low refractive index layer (2) has fine particles (2
1) and a binder (22). And a void (23) is formed between the fine particles (21). The overcoat layer (3) is made of a fluoropolymer having a weight-average molecular weight of 20,000 or more, and covers irregularities on the surface of the low refractive index layer, but does not enter the voids (23) inside the low refractive index layer. Therefore,
Even after the formation of the overcoat layer (3), the low refractive index layer (2)
(23) is maintained. In the case of this embodiment, the gap is maintained even if the amount of the overcoat layer (3) applied is equal to or larger than the volume of the gap (23) of the low refractive index layer (2). Therefore, in the embodiment shown in FIG. 4, the overcoat layer (3)
Covers the surface of the low refractive index layer (2) as a continuous layer.

[Transparent Support] As the transparent support, a plastic film is preferably used. Examples of the polymer forming the plastic film include cellulose esters (eg, triacetyl cellulose, diacetyl cellulose, propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose, nitrocellulose), polyamides, polycarbonates, polyesters (eg, polyethylene terephthalate, polyethylene Naphthalate, poly-1,4-cyclohexane dimethylene terephthalate, polyethylene-1,2-diphenoxyethane-4,4′-dicarboxylate, polybutylene terephthalate), polystyrene (eg, syndiotactic polystyrene), polyolefin ( For example, polypropylene, polyethylene, polymethylpentene), polysulfone, polyethersulfone, polyarylate, polyetherimide, Includes polymethyl methacrylate and polyether ketone. Triacetyl cellulose, polycarbonate and polyethylene terephthalate are preferred. The light transmittance of the transparent support is preferably 80% or more, and more preferably 86% or more.
The haze of the transparent support is preferably 2.0% or less, more preferably 1.0% or less. The refractive index of the transparent support is preferably from 1.4 to 1.7.

[Hard coat layer] In order to impart scratch resistance to the transparent support, it is preferable to provide a hard coat layer on the surface of the support. The hard coat layer preferably contains a cross-linked polymer. The hard coat layer containing the crosslinked polymer can be formed by applying a coating solution containing a polyfunctional monomer and a polymerization initiator on a transparent support, and polymerizing the polyfunctional monomer. The polyfunctional monomer is preferably an ester of a polyhydric alcohol and acrylic acid or methacrylic acid. Examples of polyhydric alcohols include:
Ethylene glycol, 1,4-cyclohexanol, pentaerythritol, trimethylolpropane, trimethylolethane, dipentaerythritol, 1,2,4
-Cyclohexanol, polyurethane polyols and polyester polyols. Trimethylolpropane, pentaerythritol, dipentaerythritol and polyurethane polyols are preferred. Two or more polyfunctional monomers may be used in combination. It is preferable to use a photopolymerization initiator for the polymerization reaction of the polyfunctional monomer. Examples of photopolymerization initiators include acetophenones, benzophenones, Michler's benzoylbenzoate, α-
Includes amiloxime esters, tetramethylthiuram monosulfide and thioxanthones. A photosensitizer may be used in addition to the photopolymerization initiator. Examples of photosensitizers include n-butylamine, triethylamine, tri-n
-Butylphosphine, Michler's ketone and thioxanthone.

The photopolymerization initiator is used in an amount of preferably 0.1 to 15 parts by weight, more preferably 1 to 10 parts by weight, based on 100 parts by weight of the polyfunctional monomer. The photopolymerization reaction is preferably carried out by irradiating ultraviolet rays after applying and drying the hard coat layer. It is preferable to add a filler to the hard coat layer. The filler has the function of increasing the hardness of the hard coat layer and suppressing the shrinkage of the polyfunctional monomer upon curing. It is preferable to use inorganic fine particles or organic fine particles as the filler. Examples of the inorganic fine particles include silicon dioxide particles, titanium dioxide particles, aluminum oxide particles, tin oxide particles, calcium carbonate particles, barium sulfate particles, talc, kaolin and calcium sulfate particles. Examples of organic fine particles include methacrylic acid-methyl acrylate copolymer powder, silicon resin powder, polystyrene powder, polycarbonate powder, acrylic acid-styrene copolymer powder, benzoguanamine resin powder, melamine resin powder, polyolefin powder, polyester powder, polyamide powder, polyimide Powder and polyfluoroethylene powder.
The average particle diameter of the fine particles used as the filler is 0.01
To 2 μm, preferably 0.02 to 0.5 μm.
More preferably, it is μm. The hard coat layer or its coating solution further includes a coloring agent (pigment, dye), an antifoaming agent, a thickener, a leveling agent, a flame retardant, an ultraviolet absorber,
An antioxidant or a modifying resin may be added. The thickness of the hard coat layer is preferably 1 to 15 μm.

[High Refractive Index Layer and Medium Refractive Index Layer] As shown in FIG. 1B, a high refractive index layer may be provided between the transparent support and the low refractive index layer. Further, as shown in FIG. 1C, a middle refractive index layer may be provided between the transparent support and the high refractive index layer. The refractive index of the high refractive index layer is preferably from 1.65 to 2.40, and is preferably from 1.70 to 2.2.
More preferably, it is 0. The refractive index of the middle refractive index layer is adjusted to be an intermediate value between the refractive index of the transparent support and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is
It is preferably from 1.55 to 1.70. The thickness of the high refractive index layer and the middle refractive index layer is preferably from 5 nm to 100 μm, more preferably from 10 nm to 10 μm, and most preferably from 30 nm to 1 μm. The haze of the high refractive index layer and the medium refractive index layer is
It is preferably at most 5%, more preferably at most 3%, most preferably at most 1%.
The strength of the high refractive index layer and the middle refractive index layer is preferably H or more, more preferably 2H or more, and most preferably 3H or more at a pencil hardness of 1 kg load. The high refractive index layer and the medium refractive index layer preferably contain inorganic fine particles and a polymer.

The inorganic fine particles used in the high refractive index layer and the medium refractive index layer preferably have a refractive index of 1.80 to 2.80, and more preferably 1.90 to 2.80. The weight average diameter of the primary particles of the inorganic fine particles is preferably from 1 to 150 nm, more preferably from 1 to 100 nm, and most preferably from 1 to 80 nm. The weight average diameter of the inorganic fine particles in the coating layer is preferably 1 to 200 nm, more preferably 5 to 150 nm, and more preferably 10 to 100 nm.
nm, more preferably 10 to 80 nm. The specific surface area of the inorganic fine particles is 1
Preferably 0 to 400m ² / g, more preferably from 20 to 200m ² / g, and most preferably from 30 to 150m ² / g.

The inorganic fine particles are preferably formed from a metal oxide or sulfide. Examples of metal oxides or sulfides include titanium dioxide (eg, rutile, rutile / anatase mixed crystals, anatase, amorphous structure), tin oxide, indium oxide, zinc oxide, zirconium oxide, and zinc sulfide. Titanium dioxide, tin oxide and indium oxide are particularly preferred. The inorganic fine particles contain oxides or sulfides of these metals as main components and may further contain other elements. The main component means a component having the largest content (% by weight) of the components constituting the particles.
Examples of other elements include Ti, Zr, Sn, Sb, Cu, F
e, Mn, Pb, Cd, As, Cr, Hg, Zn, A
1, Mg, Si, P and S. The inorganic fine particles may be surface-treated. The surface treatment is performed using an inorganic compound or an organic compound. Examples of the inorganic compound used for the surface treatment include alumina, silica, zirconium oxide, and iron oxide. Alumina and silica are preferred. Examples of the organic compound used for the surface treatment include a polyol, an alkanolamine, stearic acid, a silane coupling agent, and a titanate coupling agent.
Silane coupling agents are most preferred. Two or more types of surface treatments may be performed in combination. The shape of the inorganic fine particles is preferably a rice grain, a sphere, a cube, a spindle, or an irregular shape. Two or more kinds of inorganic fine particles may be used together in the high refractive index layer and the medium refractive index layer.

The proportion of the inorganic fine particles in the high refractive index layer and the medium refractive index layer is 5 to 65% by volume. The proportion of the inorganic fine particles is preferably from 10 to 60% by volume,
More preferably, it is from about 55% by volume to about 55% by volume. The inorganic fine particles are used in the form of a dispersion to form a high refractive index layer and a medium refractive index layer. It is preferable to use a liquid having a boiling point of 60 to 170 ° C. as a dispersion medium of the inorganic fine particles in the high refractive index layer and the medium refractive index layer. Examples of dispersion media include water, alcohols (eg, methanol, ethanol, isopropanol, butanol, benzyl alcohol), ketones (eg, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone), esters (eg, methyl acetate, ethyl acetate, Propyl acetate, butyl acetate, methyl formate, ethyl formate, propyl formate, butyl formate), aliphatic hydrocarbon (eg, hexane, cyclohexane), halogenated hydrocarbon (eg, methylene chloride, chloroform, carbon tetrachloride), aromatic Hydrocarbons (eg, benzene, toluene, xylene), amides (eg, dimethylformamide, dimethylacetamide, N-methylpyrrolidone), ethers (eg, diethyl ether, dioxane, tetrahydrofuran), ether alcohols (eg, 1-methyl Carboxymethyl -2
-Propanol). Particularly preferred are toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and butanol. The inorganic fine particles can be dispersed in the medium using a disperser. Examples of dispersers include sand grinder mills (eg, bead mills with pins), high speed impeller mills, pebble mills, roller mills, attritors and colloid mills. Sand grinder mills and high speed impeller mills are particularly preferred. Further, a preliminary dispersion process may be performed. Examples of the disperser used for the preliminary dispersion treatment include a ball mill, a three-roll mill, a kneader and an extruder.

It is preferable to use a polymer having a relatively high refractive index for the middle refractive index layer and the high refractive index layer. Examples of high refractive index polymers include polystyrene, styrene copolymers, polycarbonates, melamine resins, phenolic resins, epoxy resins, and polyurethanes obtained by reacting cyclic (alicyclic or aromatic) isocyanates with polyols. . Other polymers having a cyclic (aromatic, heterocyclic, alicyclic) group and polymers having a halogen atom other than fluorine as a substituent also have a high refractive index. A polymer may be formed by a polymerization reaction of a monomer capable of radical curing by introducing a double bond.

[Low Refractive Index Layer] The low refractive index layer has a refractive index of
1.20 to 1.55, preferably 1.30
It is more preferably from 1.55 to 1.55. The thickness of the low refractive index layer is preferably 50 to 400 nm,
More preferably, it is 50 to 200 nm. The low refractive index layer is formed as a layer having a porosity of 3 to 50% by volume before forming the overcoat layer. The porosity of the low refractive index layer before the formation of the overcoat layer is more preferably 5 to 35% by volume. The void in the low refractive index layer is
It can be formed as microvoids between particles or within particles using fine particles. The average particle size of the fine particles is
It is preferably 0.5 to 200 mm, and 1 to 1
The thickness is more preferably 00 nm, further preferably 3 to 70 nm, and most preferably 5 to 40 nm. The particle size of the fine particles is preferably as uniform (monodispersed) as possible. Inorganic fine particles or organic fine particles can be used for the low refractive index layer.

The inorganic fine particles are preferably amorphous. The inorganic fine particles are preferably made of a metal oxide, nitride, sulfide or halide, more preferably a metal oxide or metal halide,
Most preferably, it consists of a metal oxide or metal fluoride. As metal atoms, Na, K, Mg, Ca, B
a, Al, Zn, Fe, Cu, Ti, Sn, In, W,
Y, Sb, Mn, Ga, V, Nb, Ta, Ag, Si,
B, Bi, Mo, Ce, Cd, Be, Pb and Ni are preferred, and Mg, Ca, B and Si are more preferred. An inorganic compound containing two kinds of metals may be used. A particularly preferred inorganic compound is silicon dioxide, ie, silica.

The microvoids in the inorganic fine particles can be formed, for example, by crosslinking the silica molecules forming the particles. Crosslinking silica molecules reduces the volume and makes the particles porous. Microporous (porous) inorganic fine particles can be obtained by a sol-gel method (Japanese Patent Laid-Open No.
No. 112732, JP-B-57-9051) or a precipitation method (APPLIED OPTICS, 27 , p. 3356 (198
According to 8)), it can be directly synthesized as a dispersion. Further, the powder obtained by the drying / precipitation method can be mechanically pulverized to obtain a dispersion. Commercially available porous inorganic fine particles (for example, silicon dioxide sol) may be used.
The inorganic fine particles having microvoids are preferably used in a state of being dispersed in an appropriate medium for forming a low refractive index layer. As the dispersion medium, water, alcohol (eg, methanol, ethanol, isopropyl alcohol) and ketone (eg, methyl ethyl ketone, methyl isobutyl ketone) are preferable.

The organic fine particles are also preferably amorphous. The organic fine particles are preferably polymer fine particles synthesized by a polymerization reaction of a monomer (for example, an emulsion polymerization method). The polymer of the organic fine particles preferably contains a fluorine atom. The proportion of fluorine atoms in the polymer is preferably from 35 to 80% by weight, more preferably from 45 to 75% by weight. Examples of the fluorine atom-containing monomer used for synthesizing the fluoropolymer include fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1). , 3-dioxole), fluorinated alkyl esters of acrylic or methacrylic acid and fluorinated vinyl ethers. A copolymer of a monomer containing a fluorine atom and a monomer not containing a fluorine atom may be used. Examples of monomers containing no fluorine atom include olefins (eg, ethylene, propylene, isoprene,
Vinyl chloride, vinylidene chloride), acrylates (eg, methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate), methacrylates (eg, methyl methacrylate, ethyl methacrylate, butyl methacrylate), styrene (Eg, styrene, vinyltoluene, α-methylstyrene), vinyl ethers (eg, methyl vinyl ether), vinyl esters (eg, vinyl acetate, vinyl propionate), acrylamides (eg, N-tert-butylacrylamide, N-cyclohexylacrylamide), methacrylamides and acrylonitriles.

The microvoids in the organic fine particles can be formed, for example, by crosslinking a polymer forming the particles. Crosslinking the polymer reduces its volume,
The particles become porous. In order to crosslink the polymer forming the particles, two of the monomers for synthesizing the polymer are used.
It is preferable that 0 mol% or more be a polyfunctional monomer.
The ratio of the polyfunctional monomer is more preferably from 30 to 80 mol%, and most preferably from 35 to 50 mol%. Examples of polyfunctional monomers include dienes (eg, butadiene, pentadiene), esters of polyhydric alcohol and acrylic acid (eg, ethylene glycol diacrylate, 1,4-cyclohexane diacrylate,
Dipentaerythritol hexaacrylate), esters of polyhydric alcohol and methacrylic acid (eg, ethylene glycol dimethacrylate, 1,2,4-cyclohexanetetramethacrylate, pentaerythritol tetramethacrylate), divinyl compounds (eg, divinylcyclohexane, 1, 4-divinylbenzene), divinylsulfone, bisacrylamides (eg, methylenebisacrylamide) and bismethacrylamides.

The microvoids between the particles can be formed by stacking at least two or more fine particles. When spherical particles having the same particle size (perfectly monodispersed) are closest packed, microvoids between particles having a porosity of 26% by volume are formed. When the spherical fine particles having the same particle size are simply cubically filled, microvoids between the fine particles having a porosity of 48% by volume are formed. In an actual low refractive index layer, the porosity considerably fluctuates from the above theoretical value due to the particle size distribution of the fine particles and the presence of microvoids in the particles. Increasing the porosity lowers the refractive index of the low refractive index layer. By forming microvoids by stacking fine particles and adjusting the particle size of the fine particles, the size of the microvoids between the particles can be easily adjusted to an appropriate value (does not scatter light and does not cause a problem in the strength of the low refractive index layer). Can be adjusted. Further, by making the particle diameter of the fine particles uniform, an optically uniform low refractive index layer in which the size of the microvoids between particles is also uniform can be obtained. Thus, the low refractive index layer can be a microvoid-containing porous film microscopically, but can be an optically or macroscopically uniform film.

By forming microvoids, the macroscopic refractive index of the low refractive index layer becomes a value lower than the sum of the refractive indices of the components constituting the low refractive index layer. The refractive index of a layer is the sum of the refractive indices per volume of the components of the layer. The refractive index of a component of the low refractive index layer such as fine particles or a polymer is a value larger than 1, while the refractive index of air is 1.00. Therefore, by forming microvoids,
A low refractive index layer having a very low refractive index can be obtained. The intergranular microvoids are preferably closed in the low refractive index layer by the fine particles and the polymer. When the gap is closed, the gap remains in the low refractive index layer even after the formation of the overcoat layer. The closed void also has the advantage that light is less scattered on the surface of the low-refractive-index layer compared to an opening opened on the surface of the low-refractive-index layer.

The low refractive index layer preferably contains the polymer in an amount of 5 to 50% by weight. The polymer has a function of adhering the fine particles and maintaining the structure of the low refractive index layer including voids. The amount of the polymer used is adjusted so that the strength of the low refractive index layer can be maintained without filling the void. The amount of the polymer is preferably 10 to 30% by weight based on the total amount of the low refractive index layer. In order to adhere the fine particles with the polymer, (1) bonding the polymer to the surface treatment agent of the fine particles, (2) forming a polymer shell around the fine particles as a core, or (3) forming a polymer shell around the fine particles. It is preferable to use a polymer as the binder. (1)
The polymer to be bonded to the surface treatment agent is preferably the shell polymer of (2) or the binder polymer of (3). It is preferable that the polymer (2) is formed around the fine particles by a polymerization reaction before preparing the coating solution for the low refractive index layer. The polymer of (3) is preferably formed by adding a monomer to the coating solution for the low refractive index layer and performing a polymerization reaction simultaneously with or after the coating of the low refractive index layer.
(1) to (3) are preferably carried out in combination of two or three types, and carried out in two combinations of (1) and (3) or in a combination of three types of (1) to (3). It is particularly preferred to do so. (1) Surface treatment, (2)
The shell and the binder (3) will be described sequentially.

(1) Surface Treatment Fine particles (particularly, inorganic fine particles) are subjected to a surface treatment,
It is preferable to improve the affinity with the polymer. The surface treatment can be classified into a physical surface treatment such as a plasma discharge treatment or a corona discharge treatment, and a chemical surface treatment using a coupling agent. It is preferable to carry out only a chemical surface treatment or a combination of a physical surface treatment and a chemical surface treatment. As the coupling agent, an organoalkoxy metal compound (eg, a titanium coupling agent, a silane coupling agent) is preferably used. When the fine particles are made of silicon dioxide, surface treatment with a silane coupling agent can be particularly effectively performed. Examples of silane coupling agents include alkyl esters of orthosilicic acid (eg, methyl orthosilicate, ethyl orthosilicate, n-orthosilicate)
-Propyl, isopropyl orthosilicate, n-butyl orthosilicate, sec-butyl orthosilicate, t-orthosilicate
-Butyl) and its hydrolysates. The surface treatment with the coupling agent can be carried out by adding the coupling agent to the dispersion of fine particles, and leaving the dispersion at a temperature from room temperature to 60 ° C. for several hours to 10 days. In order to accelerate the surface treatment reaction, an inorganic acid (eg, sulfuric acid, hydrochloric acid,
Nitric acid, chromic acid, hypochlorous acid, boric acid, orthosilicic acid,
Phosphoric acid, carbonic acid), organic acids (eg, acetic acid, polyacrylic acid,
Benzenesulfonic acid, phenol, polyglutamic acid) or a salt thereof (eg, metal salt, ammonium salt) may be added to the dispersion.

(2) Shell The polymer forming the shell is preferably a polymer having a saturated hydrocarbon as a main chain. Polymers containing a fluorine atom in the main chain or side chain are preferred, and polymers containing a fluorine atom in the side chain are more preferred. Polyacrylates or polymethacrylates are preferred, and esters of fluorine-substituted alcohols with polyacrylic or polymethacrylic acid are most preferred. The refractive index of the shell polymer decreases as the content of fluorine atoms in the polymer increases. To reduce the refractive index of the low refractive index layer, the shell polymer preferably contains 35 to 80% by weight of fluorine atoms, and more preferably 45 to 75% by weight of fluorine atoms. The polymer containing a fluorine atom is preferably synthesized by a polymerization reaction of an ethylenically unsaturated monomer containing a fluorine atom. Examples of the ethylenically unsaturated monomer containing a fluorine atom include fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole), Includes esters of fluorinated vinyl ethers and fluorinated alcohols with acrylic acid or methacrylic acid.

The polymer forming the shell may be a copolymer comprising a repeating unit containing a fluorine atom and a repeating unit containing no fluorine atom. The repeating unit containing no fluorine atom is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer containing no fluorine atom. Examples of the ethylenically unsaturated monomer containing no fluorine atom include olefins (eg, ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride), acrylates (eg, methyl acrylate, ethyl acrylate, acrylic acid 2- Ethylhexyl), methacrylates (eg, methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate), styrene and its derivatives (eg, styrene, divinylbenzene, vinyltoluene, α-methylstyrene), vinyl ether ( For example, methyl vinyl ether),
Includes vinyl esters (eg, vinyl acetate, vinyl propionate, vinyl cinnamate), acrylamide (eg, N-tertbutylacrylamide, N-cyclohexylacrylamide), methacrylamide and acrylonitrile.

When a binder polymer described in (3) below is used in combination, a crosslinkable functional group may be introduced into the shell polymer, and the shell polymer and the binder polymer may be chemically bonded by crosslinking. The shell polymer may have crystallinity. When the glass transition temperature (Tg) of the shell polymer is higher than the temperature at the time of forming the low refractive index layer,
It is easy to maintain microvoids in the low refractive index layer. However, if the Tg is higher than the temperature at the time of forming the low refractive index layer, the fine particles may not be fused and the low refractive index layer may not be formed as a continuous layer (as a result, the strength may be reduced). In this case, it is desirable to use the binder polymer of (3) described later in combination and to form the low refractive index layer as a continuous layer with the binder polymer. By forming a polymer shell around the fine particles, core-shell fine particles are obtained. The core-shell fine particles preferably contain a core composed of inorganic fine particles in an amount of 5 to 90% by volume, and more preferably 15 to 80% by volume. The polymer shell is preferably formed by a radical polymerization method. The radical polymerization method is described in Takayuki Otsu and Masayoshi Kinoshita, Experimental Methods for Polymer Synthesis, Doujin Kagaku (1972) and Takayuki Otsu, Lecture Polymerization Reaction Theory 1 Radical Polymerization (I), Kagaku Dojin (1971) . Specifically, the radical polymerization method is preferably performed by an emulsion polymerization method or a dispersion polymerization method. Emulsion polymerization is described in Soichi Muroi, Chemistry of Polymer Latex, Polymer Publishing Association (1970). For the dispersion polymerization method, see Barr
ett, Keih EJ, Dispersion Polymerization in Organ
ic Media, JOHN WILLEY & SONS (1975).

Examples of the thermal polymerization initiator used in the emulsion polymerization method include inorganic peroxides (eg, potassium persulfate, ammonium persulfate), azonitrile compounds (eg, sodium azobiscyanovalerate), and azoamidine compounds (eg, 2). , 2 '
-Azobis (2-methylpropionamide) hydrochloride),
Cyclic azoamidine compound (eg, 2,2′-azobis [2
-(5-methyl-2-imidazolin-2-yl) propane hydrochloride), an azoamide compound (eg, 2,2′-azobis {2-methyl-N- [1,1′-bis (hydroxymethyl) -2) -Hydroxyethyl] propionamide). Inorganic peroxides are preferred, potassium persulfate and ammonium persulfate are particularly preferred. Examples of the thermal polymerization initiator used in the dispersion polymerization method include azo compounds (eg, 2,
2'-azobisisobutyronitrile, 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl-
2,2′-azobis (2-methylpropionate), dimethyl-2,2′-azobisisobutyrate) and organic peroxides (eg, lauryl peroxide, benzoyl peroxide, tert-butyl peroctoate) ) Is included.

In the dispersion polymerization method, it is preferable to add a polymer dispersant to the surface-treated fine particles, dissolve the monomer and the polymerization initiator, and carry out the polymerization reaction in a polymerization medium in which the produced polymer is insoluble. Examples of polymerization media include water,
Alcohol (eg, methanol, ethanol, propanol, isopropanol, 2-methoxy-1-propanol, butanol, t-butanol, pentanol, neopentanol, cyclohexanol, 1-methoxy-2
-Propanol), methyl ethyl ketone, acetonitrile, tetrahydrofuran, ethyl acetate. water,
Methanol, ethanol and isopropanol are preferred. Two or more polymerization media may be used in combination. In the emulsion polymerization method or the dispersion polymerization method, a chain transfer agent may be used. Examples of chain transfer agents include halogenated hydrocarbons (eg, carbon tetrachloride, carbon tetrabromide, ethyl dibromide acetate, ethyl tribromide acetate, ethyl dibromide benzene, ethane dibromide, ethane dichloride) , Hydrocarbons (eg, benzene, ethylbenzene, isopropylbenzene), thioethers (eg, diazothioether), mercaptans (eg, t-
Dodecyl mercaptan, n-dodecyl mercaptan, hexadecyl mercaptan, n-octadecyl mercaptan, thioglycerol), disulfide (eg, diisopropylzantogen disulfide), thioglycolic acid and derivatives thereof (eg, thioglycolic acid, 2-ethylhexyl thioglycolate) Butyl thioglycolate, methoxy butyl thioglycolate, trimethylolpropane tris (thioglycolate)). Two or more types of core-shell fine particles may be used in combination. Also, inorganic fine particles having no shell and core-shell particles may be used in combination.

(3) Binder The binder polymer is preferably a polymer having a saturated hydrocarbon or polyether as a main chain.
More preferably, the polymer has a saturated hydrocarbon as a main chain. The binder polymer is preferably crosslinked. The polymer having a saturated hydrocarbon as a main chain is preferably obtained by a polymerization reaction of an ethylenically unsaturated monomer. In order to obtain a crosslinked binder polymer, it is preferable to use a monomer having two or more ethylenically unsaturated groups. Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-cyclohexane diacrylate, pentaerythritol tetraester). (Meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethanetri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, Pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its derivatives (examples) 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinylsulfone (eg, divinylsulfone), acrylamide (eg, methylenebisacrylamide) and methacrylamide. . The polymer having a polyether as a main chain is preferably synthesized by a ring-opening polymerization reaction of a polyfunctional epoxy compound.

Instead of or in addition to the monomer having two or more ethylenically unsaturated groups, a crosslinked structure may be introduced into the binder polymer by a reaction of a crosslinkable group.
Examples of the crosslinkable functional group include an isocyanate group, an epoxy group, an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group, and an active methylene group. Vinyl sulfonic acid, acid anhydride, cyanoacrylate derivative, melamine,
Etherified methylols, esters and urethanes can also be used as monomers to introduce the crosslinked structure. A functional group that exhibits crosslinkability as a result of a decomposition reaction, such as a block isocyanate group, may be used. Further, in the present invention, the cross-linking group is not limited to the above-mentioned compound, but may be one which shows reactivity as a result of decomposition of the above-mentioned functional group. As the polymerization initiator used for the polymerization reaction and the crosslinking reaction of the binder polymer, a photopolymerization initiator is more preferable than the thermal polymerization initiator used for (2) synthesis of the shell polymer. Examples of photopolymerization initiators include acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds , Fluoroamine compounds and aromatic sulfoniums. Examples of acetophenones include 2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxydimethylphenylketone, 1-hydroxycyclohexylphenylketone, and 2-methyl-4.
-Methylthio-2-morpholinopropiophenone and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone. Examples of benzoins include benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether. Examples of the benzophenones include benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone and p-chlorobenzophenone. Examples of phosphine oxides include 2,4,6-
Trimethylbenzoyldiphenylphosphine oxide.

When used in combination with the shell polymer (2), the glass transition temperature (Tg) of the binder polymer is as follows:
It is preferably lower than the Tg of the shell polymer. The temperature difference between the Tg of the binder polymer and the Tg of the shell polymer is preferably 5 ° C. or higher, more preferably 20 ° C. or higher. The binder polymer is preferably formed by adding a monomer to the coating liquid for the low refractive index layer and performing a polymerization reaction (and, if necessary, a crosslinking reaction) simultaneously with or after the coating of the low refractive index layer. A small amount of polymer (eg, polyvinyl alcohol,
Polyoxyethylene, polymethyl methacrylate, polymethyl acrylate, diacetyl cellulose, triacetyl cellulose, nitrocellulose, polyester, alkyd resin) may be added.

[Overcoat layer] The overcoat layer is formed by applying a coating solution containing a fluorine-containing compound on the low refractive index layer. In the present invention, the ratio of the material of the overcoat layer occupying the voids of the low refractive index layer is reduced to 70% by volume.
Less than The proportion of the material of the overcoat layer occupying the voids in the low refractive index layer is preferably less than 50% by volume, more preferably less than 40% by volume,
More preferably, it is less than 30% by volume, most preferably less than 20% by volume. Various means can be adopted to form the overcoat layer while leaving the voids in the low refractive index layer. For example, as described above, if the voids of the low refractive index layer are formed in a state where the voids are closed by the fine particles and the binder polymer, the voids of the low refractive index layer remain even when the overcoat layer is formed by coating. Further, the viscosity of the coating liquid may be increased so that the coating liquid for the overcoat layer does not enter the gaps in the low refractive index layer. Specifically, the fluorine-containing compound in the overcoat layer is made into fine particles having a particle size of 10 nm or more, or the amount of the overcoat layer applied is set to 8 of the voids of the low refractive index layer.
It is adjusted to be 0% by volume or less, or the fluorine-containing compound in the overcoat layer is a fluorine-containing polymer having a weight average molecular weight of 20,000 or more. A method using a fluoropolymer having a weight average molecular weight of 20,000 or more is particularly preferred.

In the method of using the fluorine-containing compound in the overcoat layer as fine particles, the size of the fine particles is adjusted so as to be larger than the opening size of the void in the low refractive index layer. Thereby, the fine particles close the opening on the surface of the low refractive index layer, and the overcoat layer does not diffuse into the voids inside the low refractive index layer. The particle size of the fine particles is preferably 10 nm or more, more preferably 10 to 100 nm, and
The thickness is more preferably from 5 to 70 nm, and most preferably from 20 to 50 nm. The fine particles of the fluorine-containing compound can be formed by emulsifying a solution of the fluorine-containing compound. Further, fine particles may be precipitated from the solution of the fluorine-containing compound. Further, a latex of a fluoropolymer may be used as fine particles. The fluoropolymer latex can be obtained by emulsion polymerization of a fluoromonomer. A commercially available dispersion of fluorine-based fine particles can also be used. Adjust the amount of the overcoat layer to 8
In the method of adjusting the amount to be 0% by volume or less, the gap of the low refractive index layer is maintained by adjusting the amount of the overcoat layer to such an amount as to adhere to the surface. The coating amount of the overcoat layer is 70% of the gap of the low refractive index layer before the overcoat layer is formed.
It is more preferably at most 60% by volume, particularly preferably at most 60% by volume. The coating amount of the overcoat is generally 2 mg / m ² or more.

In the method in which the fluorine-containing compound in the overcoat layer is converted into a fluorine-containing polymer having a weight-average molecular weight of 20,000 or more, a coating solution for the overcoat layer is formed by using a polymer having a high molecular weight in a void inside the low refractive index layer. Avoid spreading to The weight average molecular weight of the fluoropolymer is from 40,000 to 2
More preferably, it is 100,000, most preferably 50,000 to 1,000,000.

As the fluorine-containing compound used in the overcoat layer, a fluorine-containing surfactant, a fluorine-containing polymer, a fluorine-containing ether and a fluorine-containing silane compound are preferably used. As the fluorinated surfactant, the hydrophilic portion may be any of anionic, cationic, nonionic, and amphoteric. In the fluorinated surfactant, part or all of the hydrogen atoms of the hydrocarbon constituting the hydrophobic part are replaced by fluorine atoms. The fluorine-containing polymer is preferably synthesized by a polymerization reaction of an ethylenically unsaturated monomer containing a fluorine atom (fluorine-containing monomer). Examples of the fluorine-containing monomer include fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-
Dioxol), esters of fluorinated alcohols with acrylic acid or methacrylic acid and fluorinated vinyl ethers. A copolymer obtained from two or more kinds of fluorine-containing monomers may be used. A copolymer of a fluorine-containing monomer and a monomer containing no fluorine atom may be used. Examples of monomers containing no fluorine atom include olefins (eg, ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride), acrylates (eg, methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid 2- Ethylhexyl), methacrylates (eg, methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate), styrene and its derivatives (eg, styrene, divinylbenzene, vinyltoluene, α-methylstyrene), vinyl ether ( For example, methyl vinyl ether), vinyl ester (for example, vinyl acetate, vinyl propionate, vinyl cinnamate), acrylamide (for example, N-
tert-butylacrylamide, N-cyclohexylacrylamide), methacrylamide, acrylonitrile and derivatives thereof.

In order to impart lubricity to the overcoat layer, a repeating unit composed of polyorganosiloxane may be introduced into the fluoropolymer. The fluorine-containing polymer having a repeating unit composed of a polyorganosiloxane is obtained, for example, by polymerization of a polyorganosiloxane having a reactive group at a terminal and a fluorine-containing monomer. Reactive groups chemically bond ethylenically unsaturated monomers (eg, acrylic acid and its esters, methacrylic acid and its esters, vinyl ethers, styrene and derivatives) to the ends of the polyorganosiloxane. A commercially available fluoropolymer, for example, Cytop (Asahi Glass Co., Ltd.)
), Teflon AF (manufactured by DuPont), Lumiflon (manufactured by Asahi Glass Co., Ltd.), and Opstar (manufactured by JSR Corporation) may be used. Fluorinated ethers are compounds generally used as lubricants. Examples of the fluorinated ether include perfluoropolyether and derivatives thereof. Examples of the fluorine-containing silane compound include a silane compound containing a perfluoroalkyl group (eg, heptadecafluoro-1,2,2,2-tetradecyl) triethoxysilane. A commercially available fluorine-containing silane compound, for example, KBM-7803 or KP-801M (manufactured by Shin-Etsu Chemical Co., Ltd.) may be used.

The fluorine-containing compound used in the overcoat layer preferably contains fluorine atoms in the range of 30 to 80% by weight, more preferably 40 to 75% by weight. It is particularly preferable to use a fluorine-containing polymer for the overcoat layer. Preferably, the fluoropolymer is further crosslinked. Specifically, a crosslinkable group is introduced into the fluoropolymer, or the fluoropolymer is crosslinked using a crosslinking agent. The crosslinkable group is preferably introduced as a side chain into the fluoropolymer. By copolymerizing a monomer having a crosslinkable group in the synthesis of the fluoropolymer, the crosslinkable group can be introduced into the fluoropolymer as a side chain. The fluorine-containing polymer can be crosslinked by reacting a compound having two or more crosslinkable groups (crosslinking agent) with the side chain of the fluorine-containing polymer. The crosslinkable group is preferably a functional group that reacts upon irradiation with radiation such as light (preferably ultraviolet light) or electron beam (EB) or upon heating to crosslink the fluoropolymer. More preferably, it is a functional group that is crosslinked by irradiation with radiation, and most preferably, it is a functional group that is crosslinked by irradiation with ultraviolet light. That is, when the treatment temperature of the crosslinking reaction is low, the flatness of the support is hardly deteriorated, and the heating line in the production process can be shortened. In addition, there is an advantage that irradiation of ultraviolet rays can be performed with relatively inexpensive equipment. Examples of crosslinkable groups include acryloyl, methacryloyl, allyl, isocyanate, epoxy, alkoxysilyl, aziridine, oxazoline, aldehyde, carbonyl, hydrazine, carboxyl, methylol and active methylene. The thickness of the overcoat layer is 2
To 50 nm, more preferably 5 to 30 nm, and most preferably 5 to 20 nm.

[Anti-Reflection Film] The anti-reflection film may be provided with a layer other than those described above. For example, an adhesive layer, a shield layer, a slip layer, and an antistatic layer may be provided on the transparent support in addition to the hard coat layer. The shield layer is provided to shield electromagnetic waves and infrared rays. The anti-reflection film may have an anti-glare function for scattering external light. The anti-glare function is obtained by forming irregularities on the surface of the antireflection film. The haze of the anti-reflective coating is
It is preferably from 3 to 30%, more preferably from 5 to 20%, and most preferably from 7 to 20%. The anti-reflection film is a liquid crystal display (LCD),
The present invention is applied to an image display device such as a plasma display panel (PDP), an electroluminescence display (ELD), and a cathode ray tube display (CRT). The transparent support side of the antireflection film is adhered to the image display surface of the image display device.

[0043]

[Example 1] (Preparation of coating solution for hard coat layer) Methyl ethyl ketone solution (solid content: 72% by weight, silica content: 38) of a commercially available hard coat material (Desolite Z7503, manufactured by JSR Corporation) 625 g of a mixed solvent of methyl ethyl ketone and cyclohexanone (weight ratio: 50/50)
375 g. After stirring the mixture, a pore size of 0.4
The solution was filtered through a μm polypropylene filter to prepare a coating solution for the hard coat layer.

(Preparation of Titanium Dioxide Dispersion) Titanium dioxide (primary particle weight average particle diameter: 50 nm, refractive index: 2.7)
0) 30 parts by weight, 4.5 parts by weight of anionic diacrylate monomer (trade name: PM21, manufactured by Nippon Kayaku Co., Ltd.), cationic methacrylate monomer (trade name: DM)
0.3 parts by weight of AEA (produced by Kojin Co., Ltd.) and 65.2 parts by weight of methyl ethyl ketone were dispersed by a sand grinder to prepare a titanium dioxide dispersion.

(Preparation of coating liquid for middle refractive index layer) 151.9 g of cyclohexanone and 37.0 g of methyl ethyl ketone
g, 0.14 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and a photosensitizer (Kayacure DE)
TX, manufactured by Nippon Kayaku Co., Ltd.). Further, 6.1 g of the above titanium dioxide dispersion and 2.4 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) were added, and the mixture was stirred at room temperature for 30 minutes. The solution was filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a medium refractive index layer.

(Preparation of Coating Solution for High Refractive Index Layer) 1152.8 g of cyclohexanone and methyl ethyl ketone
To 2 g, 0.06 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and a photosensitizer (Kayacure D)
0.02 g of ETX, manufactured by Nippon Kayaku Co., Ltd.) was dissolved. Further, 13.13 g of the above titanium dioxide dispersion and a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA,
After adding 0.76 g of Nippon Kayaku Co., Ltd. and stirring at room temperature for 30 minutes, the mixture was filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a high refractive index layer.

(Preparation of Coating Solution for Low Refractive Index Layer) A silane coupling agent (KBM-503, Shin-Etsu) was added to 200 g of a methanol dispersion of silica fine particles having an average particle size of 15 nm (methanol silica sol, manufactured by Nissan Chemical Industries, Ltd.). 3 g of Silicone Co., Ltd.) and 2 g of 0.1N hydrochloric acid were added, and the mixture was stirred at room temperature for 5 hours and then left at room temperature for 3 days to prepare a silane-coupled silica fine particle dispersion. To 35.04 g of the dispersion, 58.35 of isopropyl alcohol was added.
g and 39.34 g of diacetone alcohol were added.
Further, 1.02 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and a photosensitizer (Kayacure DE)
TX, manufactured by Nippon Kayaku Co., Ltd.) 0.51 g to 772.85 g
Was added to a solution of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPH).
A, manufactured by Nippon Kayaku Co., Ltd.) and dissolved.
67.23 g of the resulting solution was added to a mixture of the above dispersion, isopropyl alcohol and diacetone alcohol. The mixture is stirred for 20 minutes at room temperature and a pore size of 0.4μ
Then, the mixture was filtered through a polypropylene filter of m to prepare a coating solution for a low refractive index layer.

(Preparation of Coating Solution for Overcoat Layer) Thermally crosslinkable fluoropolymer (JN-7214, JSR Corporation)
0.6% by weight of isopropyl alcohol
Was prepared. The coarse dispersion was finely dispersed by ultrasonic waves to prepare a coating liquid for an overcoat layer. It was 30 nm when the average particle diameter of the fluoropolymer fine particles in the coating solution was measured by a Coulter counter.

(Preparation of antireflection film) Triacetyl cellulose film (TAC-TD80U, 80 μm thick)
The above coating solution for a hard coat layer was coated on a Fuji Photo Film Co., Ltd.) using a bar coater, dried at 90 ° C., and then irradiated with ultraviolet rays to cure the coated layer and obtain a thickness. A 6 μm hard coat layer was formed. On top of this, the above-mentioned coating solution for the medium refractive index layer was applied using a bar coater.
After drying at 0 ° C., the coating layer is cured by irradiating ultraviolet rays, and a medium refractive index layer (refractive index: 1.72, thickness: 0.081)
μm). The coating liquid for a high refractive index layer was applied thereon using a bar coater and dried at 60 ° C.
The coating layer was cured by irradiating ultraviolet rays to form a high refractive index layer (refractive index: 1.92, thickness: 0.053 μm). The coating liquid for a low refractive index layer is applied on the high refractive index layer using a bar coater, dried at 60 ° C., and then irradiated with ultraviolet rays to cure the coating layer. : 1.4
0, thickness: 0.085 μm). The porosity of the formed low refractive index layer was 16% by volume. The coating solution for the overcoat layer was applied on the low refractive index layer using a # 3 bar coater, and dried at 120 ° C. for 1 hour to form an antireflection film.

(Evaluation of antireflection film) The following items were evaluated for the obtained film. The results are shown in Table 1.

(1) Average reflectance 380-7 using a spectrophotometer (manufactured by JASCO Corporation)
In the wavelength region of 80 nm, the spectral reflectance at an incident angle of 5 ° was measured. The results showed an average reflectance of 450 to 650 nm.

(2) Refractive Index of Low Refractive Index Layer The refractive index of the low refractive index layer was calculated from the measurement result of the reflectance, and the refractive index of the low refractive index layer was determined by fitting.

(3) Surface Contact Angle After the antireflection film was conditioned for 2 hours at a temperature of 25 ° C. and a relative humidity of 60%, the contact angle with water was measured.

(4) Evaluation of Fingerprint Adhesion A fingerprint was adhered to the surface of the sample, and the state when the fingerprint was wiped off with a cloth (Ben Cotton, manufactured by Asahi Kasei Corporation) was observed. The sex was evaluated. A: Fingerprints were easily wiped off B: Fingerprints were wiped off when firmly rubbed C: Part of fingerprints remained without being wiped D: Most of fingerprints remained without being wiped off

(5) Evaluation of Pencil Hardness Pencil hardness evaluation specified by JIS-K-5400 was performed as an index of scratch resistance. Anti-reflection coating at a temperature of 25 ° C and a humidity of 6
After humidifying for 2 hours at 0% RH, 1k was applied using a 2H and 3H test pencil according to JIS-S-6006.
The test was performed five times with a load of g, and the hardness at which no flaw was observed was measured in a test of 3/5 or more.

(6) Scratch resistance test Using # 0000 steel wool, a load of 400 g was applied to the area of a 10-yen coin, and the evaluation was made based on the degree of scratches when ten reciprocations were made. A: No scratches are formed. B: Slightly scratched, but difficult to see. C: Notably scratched.

(7) Measurement of Dynamic Friction Coefficient The dynamic friction coefficient was evaluated as an index of the surface slip property. The coefficient of kinetic friction was determined by conditioning the sample at a temperature of 25 ° C. and a relative humidity of 60% for 2 hours, and then using a kinetic friction measuring machine (HEIDON-14).
Using a stainless steel ball with a diameter of 5 mm and a load of 100
g, values measured at a speed of 60 cm / min were used.

Example 2 The following fluorodecyl methacrylate was emulsion-polymerized in the presence of a fluorine-containing surfactant,
Latex was obtained. (Fluorodecyl methacrylate) CH ₂ ＣC (CH ₃ ) COOCH ₂ CH ₂ C ₈ F ₁₇ Latex is subjected to dialysis to remove a surfactant, and then the solid content is adjusted to a water / methanol = 7/3 composition. %. The latex was dried at room temperature and the particle size was confirmed by SEM to be about 15 nm. An antireflection film was prepared and evaluated in the same manner as in Example 1 except that the diluted latex was used as a coating liquid for an overcoat layer.
The results are shown in Table 1.

Comparative Example 1 A thermally crosslinkable fluoropolymer (JN-7214, manufactured by JSR Corporation) was dissolved in methyl isobutyl ketone to prepare a 0.6% by weight solution. An antireflection film was prepared and evaluated in the same manner as in Example 1 except that the obtained solution was used as a coating solution for an overcoat layer. The results are shown in Table 1. The material of the overcoat layer occupied 94% by volume of the voids of the low refractive index layer.

Comparative Example 2 An antireflection film was prepared and evaluated in the same manner as in Example 1 except that the overcoat layer was not provided. The results are shown in Table 1.

[0061]

[Table 1] Table 1 ──────────────────────────────────── Reflection air gap Average Low refractive index Surface Fingerprint Pencil Anti-friction film Occupancy ratio Reflectivity Layer refractive index Contact angle Adhesion Hardness Scratch coefficient ───────────────────────────── ─────── Actual 125% 0.41 1.42 100 B 3HB 0.33 Actual 2 33% 0.45 1.44 98 B 3HB 0.30 Ratio 194% 0.82 1. 47 104 B 3H A 0.25 Ratio 2 No void 0.30 1.40 45 D 2H C 0.50 ───────────

Example 3 A fluorinated silane coupling agent (KP-801M, manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in a fluorinated solvent (Fluorinert FC-7, manufactured by 3M).
A 0.15% by weight solution was prepared. The obtained solution was used as a coating solution for an overcoat layer, and was coated on the low refractive index layer prepared in Example 1 using a # 3 wire bar.
The coating was dried at 120 ° C. for 3 minutes to form an antireflection film. The coating amount of the overcoat layer was adjusted so as to be 19% by volume of the gap of the low refractive index layer. The material of the overcoat layer is
It occupied 6% by volume of the voids in the low refractive index layer. The obtained antireflection film was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 4 A heat-crosslinkable fluoropolymer (JN-7214, manufactured by JSR Corporation) was dissolved in methyl isobutyl ketone to prepare a 0.3% by weight solution. The obtained solution was used as a coating solution for the overcoat layer, and was applied on the low refractive index layer prepared in Example 1 using a # 3 wire bar, and dried at 120 ° C. for 1 hour to obtain an antireflection film. It was created. The coating amount of the overcoat layer was adjusted so as to be 37% by volume of the gap of the low refractive index layer. The material of the overcoat layer occupied 25% by volume of the voids of the low refractive index layer. The obtained antireflection film was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 5 0.3% by weight of a UV-crosslinkable fluoropolymer (TM-011, manufactured by JSR Corporation) and a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy)
0.02% by weight and a photosensitizer (Kayacure DET)
X, manufactured by Nippon Kayaku Co., Ltd.) was prepared in a methyl isobutyl ketone solution containing 0.01% by weight. The obtained solution was used as a coating solution for an overcoat layer, and was applied onto the low refractive index layer prepared in Example 1 using a # 3 wire bar.
After drying at 0 ° C. for 1 minute, the film was immediately irradiated with ultraviolet light for 1 minute using a 12 W / cm high-pressure mercury lamp to form an antireflection film. The coating amount of the overcoat layer was adjusted so as to be 37% by volume of the gap of the low refractive index layer. The material of the overcoat layer occupied 25% by volume of the voids of the low refractive index layer. The obtained antireflection film was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 3 A fluorinated silane coupling agent (KP-801M, manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in a fluorinated solvent (Fluorinert FC-7, manufactured by 3M).
A 0.15% by weight solution was prepared. The obtained solution was used as a coating solution for an overcoat layer, and was coated on the low refractive index layer prepared in Example 1 using a # 3 wire bar.
The coating was dried at 120 ° C. for 3 minutes to form an antireflection film. The coating amount of the overcoat layer was adjusted so as to be 90% by volume of the void in the low refractive index layer. The material of the overcoat layer is
It occupied 94% by volume of the voids of the low refractive index layer. The obtained antireflection film was evaluated in the same manner as in Example 1. The results are shown in Table 2.

[0066]

[Table 2] Table 2 ──────────────────────────────────── Reflection coating Air gap Average Low refractive index Surface Finger pencil Anti-dynamic friction film Amount Occupancy Reflectivity Layer refractive index Contact angle Crest Hardness Scratch coefficient ───────────────────────────── ─────── Actual 3 19% 6% 0.34 1.40 110 B 2HB 0.30 Actual 4 37% 25% 0.40 1.42 104 B 3HB 0.28 Actual 5 37% 25 % 0.38 1.42 103 B 3H B 0.23 Ratio 3 90% 94% 0.82 1.47 109 B 2H C 0.30 ───────────────────

Example 6 A commercially available fluoropolymer having a weight average molecular weight of 200,000 (Cytop CTX-809)
A, manufactured by Asahi Glass Co., Ltd.) in a commercially available fluorinated solvent (Fluorinert FC77, manufactured by Sumitomo 3M Co., Ltd.).
A 5% by weight solution was prepared. The obtained solution was used as a coating solution for an overcoat layer, and was applied onto the low refractive index layer prepared in Example 1 using a # 3 wire bar.
After drying at 0 ° C. for 1 hour, an antireflection film was formed. The coating amount of the overcoat layer was adjusted to be 120% by volume of the void. The material of the overcoat layer occupied 37% by volume of the voids of the low refractive index layer. The obtained antireflection film was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Example 7 The low molecular weight component of the thermally crosslinkable fluoropolymer (JN-7214, manufactured by JSR Corporation) used in Example 4 was removed. The molecular weight of the obtained fluoropolymer was 50,000 in number average molecular weight and 70,000 in weight average molecular weight. The obtained fluoropolymer was dissolved in methyl isobutyl ketone to prepare a 1.0% by weight solution. The obtained solution was used as a coating solution for an overcoat layer. The solution was coated on the low refractive index layer prepared in Example 1 using a # 3 wire bar, and dried at 120 ° C. for 1 hour to form an antireflection film. Created. The application amount of the overcoat layer was adjusted to be 120% by volume of the void. The material of the overcoat layer occupied 40% by volume of the voids of the low refractive index layer. The obtained antireflection film was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Example 8 The following fluorine-containing polymer was synthesized.

[0070]

Embedded image

The molecular weight of the fluoropolymer was 25,000 in number average molecular weight and 40,000 in weight average molecular weight. Dissolve the fluorine-containing polymer in methyl isobutyl ketone;
A 0% by weight solution was prepared. The obtained solution was used as a coating solution for an overcoat layer, and was applied on the low refractive index layer prepared in Example 1 using a # 3 wire bar, and was applied at 120 ° C.
For 1 hour to form an antireflection film. The application amount of the overcoat layer was adjusted to be 120% by volume of the void. The material of the overcoat layer is 4% of the gap of the low refractive index layer.
8% by volume. The obtained antireflection film was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Example 9 The ultraviolet-crosslinkable fluoropolymer used in Example 5 (TM-011, manufactured by JSR Corporation)
Was removed. The molecular weight of the obtained fluoropolymer was 60,000 in number average molecular weight and 80,000 in weight average molecular weight. The obtained fluoropolymer was dissolved in methyl isobutyl ketone to prepare a 1.0% by weight solution. The obtained solution was used as a coating solution for the overcoat layer, and was coated on the low refractive index layer prepared in Example 1 using a # 3 wire bar, dried at 60 ° C. for 1 minute, and immediately dried.
The coating layer was cured by irradiating ultraviolet rays for 1 minute using a high-pressure mercury lamp of 2 W / cm to form an antireflection film. The application amount of the overcoat layer was adjusted to be 120% by volume of the void. The material of the overcoat layer occupied 37% by volume of the voids of the low refractive index layer. The obtained antireflection film was evaluated in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 4 A fluorine-containing polymer was synthesized in the same manner as in Example 8, except that the polymerization conditions were adjusted so that the molecular weight was reduced. The molecular weight of the obtained fluoropolymer was 7,000 in number average and 11,000 in weight average molecular weight. The obtained fluorine-containing polymer was dissolved in methyl isobutyl ketone to prepare a 1.0% by weight solution. The obtained solution was used as a coating solution for an overcoat layer. The solution was coated on the low refractive index layer prepared in Example 1 using a # 3 wire bar, and dried at 120 ° C. for 1 hour to form an antireflection film. Created. The application amount of the overcoat layer was adjusted to be 120% by volume of the void. The material of the overcoat layer is
It occupied 95% by volume of the voids of the low refractive index layer. The obtained antireflection film was evaluated in the same manner as in Example 1. The results are shown in Table 3.

[0074]

[Table 3] Table 3 ──────────────────────────────────── Reflection molecule void average low refractive index Surface Finger pencil Anti-dynamic friction film Amount Occupancy Reflectivity Layer refractive index Contact angle Crest Hardness Scratch coefficient ───────────────────────────── ─────── Actual 6 200,37% 0.43 1.44 110 A 3HB 0.30 Actual 77,40% 0.42 1.44 104 A 3H A 0.12 Actual 8 44,48 % 0.48 1.45 98 A 3H A 0.22 Actual 98,000 37% 0.37 1.44 107 A 3H A 0.20 Ratio 411,000 95% 0.84 1.47 98 B 3H B 0 .25

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing various layer configurations of an antireflection film.

FIG. 2 is a schematic sectional view of a low refractive index layer and an overcoat layer according to a preferred embodiment of the present invention.

FIG. 3 is a schematic sectional view of a low refractive index layer and an overcoat layer according to another preferred embodiment of the present invention.

FIG. 4 is a schematic sectional view of a low refractive index layer and an overcoat layer according to still another preferred embodiment of the present invention.

[Description of Signs] 1 Transparent support 2 Low refractive index layer 3 Overcoat layer 4 Hard coat layer 5 High refractive index layer 6 Medium refractive index layer 21 Fine particles of low refractive index layer 22 Binder of low refractive index layer 23 Low refractive index Void in layer 31 Fine particles of fluorine-containing compound

Claims (9)

[Claims] 1. An antireflection film comprising a transparent support and a low refractive index layer having a lower refractive index than the transparent support and a porosity of 3 to 50% by volume. An overcoat layer containing a fluorine-containing compound is further laminated thereon, and the ratio of the material of the overcoat layer occupying the voids in the low refractive index layer is less than 70% by volume. film. 2. The antireflection film according to claim 1, wherein the overcoat layer contains fine particles of a fluorine-containing compound having a particle size of 10 nm or more. 3. The antireflection film according to claim 1, wherein the amount of the overcoat layer applied is 80% by volume or less of the amount of voids in the low refractive index layer. 4. The antireflection film according to claim 1, wherein the fluorine-containing compound is a fluorine-containing polymer having a weight average molecular weight of 20,000 or more. 5. The antireflection film according to claim 1, wherein the fluorine-containing compound is a fluorine-containing polymer, and the fluorine-containing polymer is crosslinked after forming the overcoat layer. 6. The antireflection film according to claim 5, wherein the fluoropolymer is crosslinked by irradiation with radiation. 7. The antireflection film according to claim 1, wherein the low refractive index layer contains fine particles, and a void is formed between or within the fine particles. 8. The antireflection film according to claim 1, wherein a high refractive index layer having a refractive index higher than that of the transparent support is provided between the transparent support and the low refractive index layer. 9. An image display device comprising: a transparent support and a low refractive index layer having a lower refractive index than the transparent support and a porosity of 3 to 50% by volume are laminated on the image display surface in this order. An overcoat layer containing a fluorine-containing compound is further laminated on the low-refractive-index layer, and a ratio of a material of the overcoat layer occupying a void in the low-refractive-index layer is less than 70% by volume. An image display device, comprising: