JPH1164601A - Antireflection film and display device arranged therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process having adaptability to mass production of large sized antireflection films which exhibit uniformly low reflectivity (reflectivity <=1%) in a wide wavelength region and are simultaneously excellent in film strength and heat resistance. SOLUTION: This antireflection film has at least one layer of a low-refractive index layer which has microvoids of <=200 nm in average diameter and consists of a fluorine-contained polymer. The fluorine-contained polymer is produced by the polymn. reaction of a monomer contg. at least one kind of the corresponding fluorine-contained monomer in a stage for production and is formed with the microvoids formed by the deposition and flocculation of the polymer formed in the polymn. process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-reflection film which is excellent in mass productivity and anti-contamination properties, and at the same time, realizes high film strength, and a display device having the anti-reflection film.

[0002]

2. Description of the Related Art In recent years, with the spread of liquid crystal display devices, enlargement and outdoor use, toughness under use conditions, for example, improvement in resistance to reflected light (ensure visibility), antifouling property and heat resistance. Is required. Improving the visibility of a display device is an issue related to the main function of the device, and naturally has high importance, and measures for improving the visibility are being actively studied. Generally, visibility is reduced by the reflection of scenery due to surface reflection of external light, and as a countermeasure against this, a method of providing an antireflection film on the outermost surface is generally performed. However,
Since this antireflection film is provided on the outermost surface in order to exhibit its function, many issues of high quality are inevitably concentrated on the performance of the antireflection film from the viewpoint of toughness. For example, reduction of reflectance to the limit (reflectance of 1% or less), prevention of adhesion of fingerprints and fats and oils, easy removal, and maintenance of various performances in a high temperature environment such as under the sun or in a car interior.

Conventionally, as an antireflection film having a wide wavelength range and a low reflectance having a performance capable of covering the entire wavelength range of visible light, a multilayer film formed by laminating a transparent thin film such as a metal oxide has been used. Although a single-layer film is effective for monochromatic light, it cannot effectively prevent reflection of light having a certain wavelength range, whereas in such a multilayer film, the larger the number of layers, the wider the wavelength range. This is because it becomes an effective antireflection film. Therefore, a conventional antireflection film has been used in which three or more layers of metal oxides or the like are laminated by means such as physical or chemical vapor deposition. However, such multi-layer deposited anti-reflection film, according to the relationship between the refractive index and the film thickness of each layer designed optimally in advance, it is necessary to perform the deposition with its film thickness controlled with high precision many times, It is very expensive and poor in suitability for mass production, which makes it very difficult to obtain a large area film. Also,
These multilayer anti-reflection coatings are poor in anti-staining properties such as scratch resistance or fingerprint adhesion on the surface. To improve the anti-reflection coating, for example, a new layer made of a fluorine-containing resin is applied. Processing that could sacrifice was necessary.

On the other hand, in addition to the above-described method using a multilayer film, a method for obtaining an effective anti-reflection effect by a film whose refractive index gradually changes at the interface with air is conventionally known. For example, JP-A-2-245702 discloses that
The SiO ₂ ultrafine particles and MgF ₂ ultrafine particles having an intermediate refractive index of the glass substrate and the MgF ₂ were mixed and applied to a glass substrate, gradually SiO toward the coating film surface from the glass substrate surface
_{It is described that when} the mixing ratio of MgF ₂ is increased by decreasing the mixing ratio of ₂ , the change in the refractive index at the interface between the coating surface and the glass substrate becomes gentle, and an antireflection effect is obtained.

Further, Japanese Patent Application Laid-Open No. 5-13021 discloses that
An antireflection film comprising two layers using ultrafine particles having MgF ₂ and SiO ₂ dispersed in ethyl silicate is disclosed. For example, the first layer is composed of 7 MgF ₂ / SiO _2.
The second layer is a layer in which MgF ₂ / SiO ₂ is 1/1, the refractive index of the first layer is 1.42, and the refractive index of the second layer is 1.44. Therefore, the change in the refractive index cannot be said to be large, and a sufficient antireflection effect cannot be obtained.

[0006] Also, JP-A-7-92305 discloses that
Refractive index of 1.428 consisting of core and surrounding shell
An anti-reflection film is disclosed which comprises an upper layer portion (low refractive index) having irregularities on the surface formed of air and fine particles and a lower layer portion formed only of fine particles.
And the core of the ultrafine particles is methyl methacrylate, methacrylic acid, trifluoroethyl acrylate,
Formed from N-isobutoxymethylacrylamide,
The shell part is formed from styrene, acrylic acid, and butyl acrylate.

Further, Japanese Patent Application Laid-Open No. Hei 7-168006 discloses that the surface formed of air and fine particles (eg, MgF ₂ ) has an irregular upper layer portion (low refractive index) and a fine particle only middle layer portion (medium refractive index). ), And an antireflection film comprising fine particles and a lower layer portion formed of a binder.

However, the above-mentioned Japanese Patent Application Laid-Open No. Hei 2-2457
02, JP-A-5-13021, JP-A-7-
The antireflection films described in JP-A-92305 and JP-A-7-168006 utilize the principle that the refractive index to air gradually changes in the thickness direction. These antireflection coatings require complicated operations and skilled techniques for their preparation, and are strictly limited in the manufacturing process (for example, baking temperature, heat resistance of the support, etc.), and are obtained. No satisfactory antireflection effect was obtained.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to exhibit a uniformly low reflectance (reflectance of 1% or less) over a wide wavelength range, and at the same time, to obtain film strength, durability, adhesion to dirt, and heat resistance. It is an object of the present invention to provide an antireflection film excellent in various performances, such as low cost, by a method suitable for large-scale and large-area production.

[0010]

The above-mentioned problems are solved by the following antireflection film. (1) An antireflection film having a microvoid having an average diameter of 200 nm or less and having at least one low-refractive-index layer made of a fluoropolymer and having a refractive index of 1.45 or less. An antireflection film, wherein the microvoids are formed by precipitation and agglomeration of a polymer generated in the polymerization process, wherein the microvoids are formed by a monomer polymerization reaction containing at least one fluorine-containing monomer. (2) The antireflection film according to (1), wherein the low refractive layer contains at least 0.1 weight fraction or more of fluorine atoms. (3) The antireflection film according to (1) or (2), wherein the low refractive index layer has a void of at least 5% by volume. (4) The antireflection method according to any one of (1) to (3), wherein in the process of forming the low refractive index layer, a solvent in which a monomer to be used is soluble and a generated polymer is insoluble is used. film. (5) The antireflection film according to any one of (1) to (3), wherein the low refractive index layer is formed on a layer having a higher refractive index. (6) The antireflection film according to any one of (1) to (3), wherein the haze value of the antireflection film is 3 to 30%. (7) A display device on which the antireflection film of (1) to (3) is arranged.

In the antireflection film of the present invention, it is preferable that the low refractive index layer containing the microvoids is formed of two layers formed on a high refractive index layer having a higher refractive index. Further, it is preferable that these layers are provided on a support (preferably a transparent film). Further, the antireflection film of the present invention, the low refractive index layer containing the microvoids is formed on a high refractive index layer having a higher refractive index, further high refractive index layer, It is preferable to include three layers formed on a middle refractive index layer having a low refractive index and a higher refractive index than the low refractive index layer. Further, it is preferable that these layers are provided on a support (preferably a transparent film).

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The excellent antireflection film obtained by the antireflection film of the present invention will be described below. In the following description, the voids in the antireflection film obtained by forming the film by the method of the present invention are “microvoids”, the polymer aggregate structure part forming the continuous phase in the antireflection film is “fibrils”, and the monomer is polymerized. The method of forming a microvoided film by precipitation and aggregation of a polymer is referred to as a “deposition method”.

The antireflection film of the present invention comprises a low refractive index layer formed of a polymer formed by forming a corresponding monomer and then polymerizing the same. This low-refractive-index layer is in a uniform liquid film state immediately after the formation of the monomer, but when the monomer undergoes a polymerization reaction in this liquid film, the produced polymer is insolubilized and precipitates and aggregates. Form a fine porous structure. This porous structure results in microvoids in the film, giving a film of low refractive index based on the principles described below.

[0014] The above-mentioned polymer is generally deposited from a uniform monomer film state, in which a polymer chain grows with the progress of polymerization, and a cohesive force between the molecular chains and a coexisting monomer or solvent with the development of a network structure. Since fibrils are generated by phase separation, the microvoids formed between the fibrils are generally uniform in the size of the voids and the intervals between the voids. Although the low refractive index layer of the present invention is a film having a non-uniform structure in a micro structure, it can be regarded as one uniform layer when viewed in the order of the wavelength of light.

The refractive index of air on the surface of the low refractive index layer of the present invention is 1, and the refractive index of the polymer forming the fibrils of the present invention is higher than the refractive index of air, generally 1.25 to 1. Between 50. Since the low refractive index layer of the present invention is a film in which the fibril phase and the air phase can be regarded as optically uniform, the refractive index is observed as a volume average value of the refractive index of air and the refractive index of fibril. become. Therefore,
In the present invention, the volume fraction of the microvoids is made smaller than the refractive index of the material using the low refractive index layer without impairing transparency by making the formed microvoids sufficiently small with respect to the wavelength of visible light. Can be lowered. The average diameter of the microvoids is generally 5 to 200 nm.
Is preferably 5 to 50 nm. The thickness of the low refractive index layer is generally in the range of 5 to 400 nm,
It is preferably 00 nm. If the diameter of the microvoids increases, scattering at the air-film interface increases, and if it exceeds 200 nm, film haze undesirably occurs.

The average diameter of the microvoids in the present invention is defined by a diameter of a circle equal to the opening area of each microvoid observed by observing a cross section of the film with a scanning electron microscope, and at least 100 or more. The average value of the equivalent circular diameter calculated from the opening area of the microvoid is used.

FIG. 1 shows another typical example of the antireflection film of the present invention. A high refractive index layer 12 is formed on a transparent film (support) 13, and a low refractive index layer 11 is formed on the high refractive index layer 12. The increase in the number of layers constituting the antireflection film generally expands the wavelength range of light to which the antireflection film can be applied. This is based on the principle of forming a conventional multilayer film using a metal compound.

In the antireflection film having two layers, the high refractive index layer 12 and the low refractive index layer 11 generally satisfy the following conditions (1) and (2), respectively. mλ / 4 × 0.7 <n1 d1 <mλ / 4 × 1.3 (1) nλ / 4 × 0.7 <n2 d2 <nλ / 4 × 1.3 (2) In the above equation, m is Positive integer (typically 1, 2, or 3)
Where n 1 represents the refractive index of the high refractive index layer, d 1 represents the layer thickness (nm) of the high refractive index layer, n represents a positive odd number (generally 1), and n 2 represents the low refractive index layer. Represents the refractive index, and d2 represents the layer thickness (nm) of the low refractive index layer.
The refractive index n1 of the high refractive index layer is generally at least 0.05 higher than the transparent film, and the refractive index n1 of the low refractive index layer is higher.
2 is generally at least 0.1% higher than the refractive index of the high refractive index layer.
Low and at least 0.05 lower than the transparent film. Further, the refractive index n1 of the high refractive index layer is generally 1.5 to 1.7.
In the range. The above conditions (1) and (2) are conventionally well-known conditions.
No. 01 publication.

FIG. 2 shows another typical example of the antireflection film of the present invention. A middle refractive index layer 22 is formed on a transparent film (support) 23, a high refractive index layer 24 is formed on the middle refractive index layer 22, and a low refractive index layer 21 is formed on the high refractive index layer 24. ing. The refractive index of the middle refractive index layer 22 is
4 and a value between the low refractive index layer 21. The antireflection film of FIG. 2 has a wider applicable wavelength range of light than the antireflection film of FIG.

In the above three-layer antireflection film, the medium, high and low refractive index layers generally satisfy the following conditions (3) to (5), respectively. hλ / 4 × 0.7 <n3 d3 <hλ / 4 × 1.3 (3) kλ / 4 × 0.7 <n4 d4 <kλ / 4 × 1.3 (4) jλ / 4 × 0.7 < n5 d5 <jλ / 4 × 1.3 (5) In the above formula, h is a positive integer (generally 1, 2, or 3)
, N3 represents the refractive index of the medium refractive index layer, d3 represents the layer thickness (nm) of the medium refractive index layer, k represents a positive integer (generally 1, 2 or 3), and n4 represents the high refractive index. Represents the refractive index of the refractive index layer, d4 represents the layer thickness (nm) of the high refractive index layer, j represents a positive odd number (generally 1), n5 represents the refractive index of the low refractive index layer, and d5 represents the thickness (nm) of the low refractive index layer. The refractive index n3 of the medium refractive index layer is generally in the range of 1.5 to 1.7, and the refractive index n3 of the high refractive index layer is
4 is generally in the range of 1.7 to 2.2.

The microvoid-containing low refractive index film of the present invention comprises:
There are no particular restrictions on the method of preparation and the monomers used as long as the fluoropolymer produced during the polymerization phase separates and precipitates from the polymerization system. A monomer for providing such a film and a polymerization method thereof will be described. (1) Method for Forming Film (Polymerization) In the polymerization method for forming the low refractive index layer of the present invention, a polymer formed in the process is precipitated from a reaction system, and a porous film is obtained after removing non-polymerized components. There is no particular limitation as long as it is normal polymerization mode such as bulk polymerization, dispersion polymerization and precipitation polymerization. The form of the polymerization initiation is not particularly limited, such as ordinary radical polymerization (thermal initiation, photo initiation), anionic polymerization (thermal initiation, photo initiation), and cationic polymerization (thermal initiation, photo initiation).

Among these, as a method for forming microvoids reliably and efficiently, a solvent which is a good solvent for a monomer but is a poor solvent for a polymer is used to promote coagulation and precipitation of a polymer formed as the polymerization proceeds. `` Poor solvent method ''
And a polyfunctional monomer as a monomer, and as the polymerization proceeds, the network structure of the generated polymer (network)
The “crosslinking method” of developing and coagulating is particularly preferably used. Not limited to the poor solvent method and the crosslinking method, examples of the solvent preferably used for forming the low refractive index layer of the present invention include alkanes (hexane, heptane, dodecane, petroleum ether, liquid paraffins, etc.), ethers (E.g., dibutyl ether, tetrahydrofuran, dihexyl ether), ketones (e.g., acetone, 2-butanone, cyclohexanone), esters (e.g., ethyl acetate, butyl acetate, dibutyl phthalate), amides (e.g., dimethylformamide, dibutylacetamide) It is also preferable to use these mixed solvent systems for the purpose of controlling the solubility of the formed polymer and the strength of the formed film. After the completion of the polymerization reaction, these solvents are preferably removed by evaporative drying or washing. In this case, it is preferable to use a solvent having a low boiling point that is mutually soluble with the solvent used and does not dissolve the produced polymer. The polymerization temperature is not particularly limited. Usually, it is preferably lower than the boiling point of the monomer or solvent to be used and lower than the deformation temperature of the support to be used. Therefore, the temperature is preferably from -78 ° C to 200 ° C, particularly preferably from room temperature to 180 ° C.

(2) Monomer for Forming Film The monomer unit for giving the fluorine-containing polymer of the present invention is not particularly limited except that it necessarily contains a fluorine-containing monomer so that the polymer contains a fluorine atom. A polyfunctional monomer may be used in a free ratio in order to express performance by a monomer or a crosslinking method. However, from the viewpoint of the refractive index,
It is preferred that the resulting polymer contains at least 0.1 weight fraction of fluorine atoms, and particularly preferred is the case where the resulting polymer contains at least 0.3 weight fraction of fluorine atoms. Specific examples of the fluorine-containing monomer preferably used in the present invention include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluorobutadiene, perfluoro-2,2-dimethyl-1) ,
3-dioxole, etc.), acrylic or methacrylic acid moieties and fully fluorinated alkyl, alkenyl, aryl esters (for example, compounds represented by the following general formula),
Fully or partially fluorinated vinyl ethers, fully or partially fluorinated vinyl esters, fully or partially fluorinated vinyl ketones, and the like.The desired polymer can be obtained by copolymerizing any of these monomers in any ratio. it can.

[0024]

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In the formula, R ¹ is a hydrogen atom, having 1 to 3 carbon atoms.
Represents an alkyl group or a halogen atom. Rf represents a completely or partially fluorinated alkyl group, alkenyl group, heterocycle or aryl group. R ² and R ³ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a heterocyclic ring, an aryl group or a group defined by Rf. R ¹ , R ² , R ³ and Rf may each have a substituent other than a fluorine atom. Further, any two or more groups of R ² , R ³ and Rf may be bonded to each other to form a ring structure.

[0026]

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In the formula, A represents a fully or partially fluorinated n-valent organic group. R ⁴ represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or a halogen atom. R ⁴ may have a substituent other than a fluorine atom. n represents an integer of 2 to 8. Examples of the fluorine-containing monomer preferably used for the low refractive index film of the present invention are shown below, but the present invention is not limited to these specific structures.

[0028]

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[0029]

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[0030]

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[0031]

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[0032]

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[0033]

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Further, in addition to the above-mentioned fluorine-containing monomer, a monomer containing no fluorine atom may be used in combination for the purpose of controlling the strength of the film to be formed, the size of microvoids, the surface characteristics, the surface shape and the like. There are no particular restrictions on the monomer units that can be used in combination, and any monomer unit that can be copolymerized by ordinary radical polymerization or ionic polymerization can be suitably used. Preferred examples of such a monomer include, for example, olefins (ethylene, propylene, isoprene, butadiene, vinyl chloride, vinylidene chloride, 6-hydroxy-1-hexene, cyclopentadiene, 4-pentenoic acid, methyl 8-nonenoate, Vinylsulfonic acid, trimethylvinylsilane, trimethoxyvinylsilane, etc.), unsaturated carboxylic acids and salts thereof (acrylic acid, methacrylic acid, itaconic acid, maleic acid, sodium acrylate, ammonium methacrylate, potassium itaconate, etc.), β- Esters of saturated carboxylic acids (methyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, 2-chloroethyl acrylate,
Benzyl acrylate, 2-cyanoethyl acrylate, methyl methacrylate, butyl methacrylate, 2
-Hydroxyethyl methacrylate, glycidyl methacrylate, glycerin monomethacrylate, 2-acetoxyethyl methacrylate, phenyl methacrylate,
Tetrahydrofurfuryl methacrylate, 2-methoxyethyl methacrylate, ω-methoxy polyethylene glycol methacrylate (additional mole number = 2 to 100), ω-hydroxy polyethylene glycol methacrylate (additional mole number = 2 to 100), ω-
Hydroxypolypropylene glycol methacrylate (additional moles = 2 to 100), 3-N, N-
Dimethylaminopropyl methacrylate, chloro-3-
N, N, N-trimethylammoniopropyl methacrylate, 2-carboxyethyl methacrylate, 3-sulfopropyl methacrylate, 4-oxysulfobutyl methacrylate, monobutyl maleate, dimethyl maleate, monomethyl itaconate, dibutyl itaconate, 3
-Trimethoxysilylpropyl methacrylate, allyl methacrylate, 2-isocyanatoethyl methacrylate, etc., amides of unsaturated carboxylic acids (acrylamide, methacrylamide, N-methylacrylamide,
N, N-dimethylacrylamide, N-methyl-N-hydroxyethylmethacrylamide, N-tertbutylacrylamide, N-tertoctylmethacrylamide, N-cyclohexylacrylamide, N-phenylacrylamide, N- (2-acetoacetoxyethyl)
Acrylamide, N-acryloylmorpholine, diacetone acrylamide, itaconic acid diamide, N-methylmaleimide, 2-acrylamide-methylpropanesulfonic acid, etc., unsaturated nitriles (acrylonitrile, methacrylonitrile, etc.), styrene derivatives (styrene , Vinyltoluene, p-tertbutylstyrene, methyl vinylbenzoate, α-methylstyrene, p-
Chloromethylstyrene, vinylnaphthalene, p-hydroxymethylstyrene, sodium p-styrenesulfonate, potassium p-styrenesulfinate, p-aminomethylstyrene, etc., vinyl ethers (methyl vinyl ether, butyl vinyl ether, methoxyethyl vinyl ether, etc.) ), Vinyl esters (vinyl acetate, vinyl propionate, vinyl benzoate, vinyl salicylate vinyl chloroacetate, etc.), and other polymerizable monomers (N-vinylimidazole, 4-vinylpyridine, N-
And vinylpyrrolidone. However, it is desirable that these monomers are copolymerized and used in a necessary minimum amount which does not increase the refractive index of the film.

The surface energy of the film can be adjusted by using a necessary amount of the monomer having a hydrophilic group in the above examples.
The type of the hydrophilic group is not particularly limited, and for example, a monomer having a structure such as a carboxylic acid and a salt thereof, a sulfonic acid and a salt thereof, a sulfuric acid half ester and a salt, a hydroxyl group, and a polyoxyethylene group are preferable.

Further, by copolymerizing an arbitrary polyfunctional monomer in addition to the above monofunctional monomer, the deposition rate, hardness and swelling of the film with respect to the solvent can be controlled. The polyfunctional monomer to be used is not particularly limited and may be suitably used as long as it is commercially available or has a plurality of polymerizable unsaturated groups in one molecule of the synthesis. From the viewpoint of lowering the refractive index of the low refractive layer to be formed, the polyfunctional monomer may be selected from the fluorine-containing polyfunctional monomers exemplified above. Specific examples of the polyfunctional monomer include, for example, olefins (butadiene, pentadiene, 1,4-divinylcyclohexane, 1,2,5-trivinylcyclohexane and the like), esters of acrylic acid and methacrylic acid (ethylene glycol diacrylate) Ethylene glycol dimethacrylate, 1,4-cyclohexane diacrylate, pentaerythritol tetramethacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, trimethylolethanetri (meth) acrylate, dipentaerythritol pentamethacrylate, pentaerythritol hexaacrylate, 1,2,4-cyclohexanetetramethacrylate), styrene derivatives (1,4-divinylbenzene, 4-vinylbenzoate) Acid-2-acryloylethyl ester, etc.), vinyl sulfones (divinyl sulfone, etc.), acrylamides (methylenebisacrylamide, diacryloylpiperazine, etc.), methacrylamides (methylenebismethacrylamide, dimethacryloylpiperazine, etc.) and the like. Can be.

The refractive index of the fluoropolymer constituting the low refractive index film of the present invention decreases almost linearly in proportion to the fluorine atom content. Furthermore, the refractive index of the low refractive index layer is not determined only by the refractive index of the polymer forming the film, but further decreases as the microvoid content in the film increases. As described above, by increasing both the fluorine content and the microvoid content, the refractive index of the low refractive index layer can be sufficiently reduced. Therefore, the fluoropolymer is generally 0.10 weight fraction or more (preferably, 0.30 to 0.7
5% by weight, particularly preferably 0.35 to 0.75% by weight) of the fluorine atom, and the low refractive index layer generally has a thickness of 0.05%.
A microvoid having a volume fraction of 5 to 0.50 (preferably 0.10 to 0.50 volume fraction, particularly preferably 0.10 to 0.50 volume fraction)
~ 0.28 volume fraction).

The antireflection film of the present invention generally comprises a support and a low refractive index layer provided thereon. The support is usually a transparent film. Materials for forming the transparent film include cellulose derivatives (eg, diacetylcellulose, triacetylcellulose (TAC), propionylcellulose, brylcellulose, acetylpropionylcellulose, and nitrocellulose), polyamides, polycarbonates (eg, US Pat. No. 3,023,101). Described), polyesters (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, poly-1,4-cyclohexane dimethylene terephthalate, polyethylene-1,2-diphenoxyethane-4,4'-dicarboxylate, and Tokubyosho) 48-4
0414), polystyrene, polyolefins (eg, polyethylene, polypropylene and polymethylpentene), polymethyl methacrylate, syndiotactic polystyrene, polysulfone,
Polyethersulfone, polyetherketone, polyetherimide and polyoxyethylene can be mentioned. Triacetyl cellulose, polycarbonate and polyethylene terephthalate are preferred. The refractive index of the transparent film is preferably from 1.40 to 1.60.

When the antireflection film of the present invention is a multilayer film, the low refractive index layer generally has at least one layer having a higher refractive index than the low refractive index layer (ie, the high refractive index layer, (Refractive index layer). As an organic material for forming a layer having a higher refractive index than the above, a thermoplastic resin (eg, polystyrene, polystyrene copolymer,
A polymer having an aromatic ring, a heterocyclic ring, an alicyclic group other than polycarbonate or polystyrene, or a polymer having a halogen group other than fluorine); a thermosetting resin composition (eg, a melamine resin, a phenol resin, or an epoxy resin) A curing agent); a urethane-forming composition (eg, a combination of an alicyclic or aromatic isocyanate and a polyol); and a radically polymerizable composition (a double bond is formed in the above compound (polymer or the like). A composition containing a modified resin or a prepolymer which is capable of radical curing by being introduced). Materials having high film forming properties are preferred. For the layer having a higher refractive index than the above, inorganic fine particles dispersed in an organic material can also be used. As the organic material used in the above, an inorganic fine particle generally has a high refractive index, so that a material having a lower refractive index than that of a case where the organic material is used alone can be used. Examples of such materials, in addition to the organic materials described above, vinyl copolymers including acrylics, polyesters, alkyd resins, cellulose polymers,
Examples thereof include various organic materials which are transparent and stably disperse inorganic fine particles, such as urethane resins, various curing agents for curing these, and compositions having a curable functional group. Particularly, from the viewpoint of film strength, the following specific examples can be given as those preferably used as the composition having the curable functional group.

Further, an organic-substituted silicon-based compound can be included therein. These silicon-based compounds have the general formula: ^{_{R 11 a R 12 b SiX 4-}} (a + b) ( wherein, R ¹¹ and R ¹² are each an alkyl group, an alkenyl group, an allyl group or a halogen, epoxy, amino X represents a hydrolyzable group selected from an alkoxyl group, an alkoxyalkoxyl group, a halogen atom and an acyloxy group, and a + b is 1 or 2. Under the conditions, a and b are 0, 1, respectively.
Or 2. ) Or a hydrolysis product thereof.

Preferred inorganic compounds of the inorganic fine particles dispersed therein include oxides of metal elements such as aluminum, titanium, zirconium, antimony and tin. These compounds are in the form of fine particles,
That is, it is commercially available as a powder or a colloidal dispersion in water and / or other solvents. These are further mixed and dispersed in the above organic material or organosilicon compound for use.

As the material for forming the layer having a higher refractive index, inorganic materials which are film-forming and can be dispersed in a solvent or are themselves liquid (eg, alkoxides of various elements, salts of organic acids, A coordination compound (eg, a chelate compound) bonded to a coordination compound, an active inorganic polymer) can be exemplified. Preferred examples thereof include titanium tetraethoxide, titanium tetra-i-propoxide, titanium tetra-n-propoxide, titanium tetra-n-butoxide, titanium tetra-sec-butoxide, titanium tetra-tert-butoxide, Aluminum triethoxide,
Aluminum tri-i-propoxide, aluminum tributoxide, antimony triethoxide, antimony tributoxide, zirconium tetraethoxide, zirconium tetra-i-propoxide, zirconium tetra-n-propoxide, zirconium tetra-n-butoxide, zirconium Metal alcoholate compounds such as tetra-sec-butoxide and zirconium tetra-tert-butoxide; diisopropoxytitanium bis (acetylacetonate), dibutoxytitanium bis (acetylacetonate), diethoxytitanium bis (acetylacetonate), Bis (acetylacetone zirconium), aluminum acetylacetonate, aluminum di-n-butoxide monoethylacetoacetate,
Chelating compounds such as aluminum di-i-propoxide monomethyl acetoacetate and tri-n-butoxide zirconium monoethyl acetoacetate; and active inorganic polymers mainly containing zirconium ammonium zirconate or zirconium. In addition to those described above, various alkyl silicates or hydrolysates thereof, particularly fine particles of silica, particularly silica gel dispersed in a colloidal form can be used as those having a relatively low refractive index but which can be used in combination with the above compounds. .

The anti-reflection film of the present invention can be treated so that the surface has an anti-glare function (ie, a function of scattering incident light on the surface to prevent a scene around the film from shifting to the film surface). . For example, an antireflection film having such a function forms fine irregularities on the surface of a transparent film, and forms an antireflection film (eg, a low refractive index layer, etc.) on the surface.
Is obtained. The formation of the fine irregularities is performed, for example, by forming a layer containing inorganic or organic fine particles on the surface of the transparent film. Or,
Fine particles having a particle diameter of 50 nm to 5 μm, which are different from the fluororesin fine particles, are introduced into the coating solution for forming the low refractive index layer in an amount of 0.1 to 50% by weight of the fluororesin fine particles. Unevenness may be formed on the surface. An anti-reflection film having an anti-glare function (ie, an anti-glare treatment)
Generally, it has a haze of 3 to 30%.

The antireflection film of the present invention (preferably an antireflection film having an antiglare function) is used for a liquid crystal display (LC).
D), an image display device such as a plasma display (PDP), an electroluminescence display (ELD), and a cathode ray tube display (CRT).
In the image display device having such an antireflection film, reflection of incident light is prevented, and visibility is remarkably improved. A liquid crystal display (LCD) provided with the antireflection film of the present invention has, for example, the following configuration. A liquid crystal display comprising a pair of substrates having transparent electrodes, a nematic liquid crystal sealed between the substrates, and a polarizing plate disposed on both sides of the liquid crystal cell, wherein at least one of the polarizing plates has a surface on which the present invention is applied. Liquid crystal display device having an anti-reflection film.

The low-refractive-index layer of the antireflection film of the present invention is prepared, for example, by applying a coating solution (fluorine resin fine particles dispersed in water and / or an organic solvent) for forming this layer to a curtain flow coat or a dip coat. It is formed by applying to a transparent film or a high or middle refractive index layer or the like by an application method such as spin coating, roll coating or the like, and drying.

In the present invention, a hard coat layer, an anti-moisture layer, an anti-static layer and the like may be provided on the transparent film as an intermediate layer. As the hard coat layer, in addition to acrylic-based, urethane-based, and epoxy-based polymers and / or oligomers and monomers, silica-based materials can also be used.

[0047]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Example 1 (Coating of antireflection layer and evaluation of performance) Using a low refractive index layer coating solution (C1 to C5) shown in Table 1 below, a triacetyl cellulose (hereinafter referred to as TAC) film was coated using a bar coater. Polymerization was performed under the conditions described in the same table to form a low refractive index layer having a thickness of 100 nm. The obtained films (X1 to X5) were measured for refractive index and luminous reflectance (average reflectance value at a light wavelength of 400 nm to 700 nm) and evaluated for film strength. The porosity of the low-refractive-index layer was obtained by measuring the refractive index of the layer with an Abbe refractive index system and calculating the volume fraction of air from the difference from the calculated value of the refractive index of the layer obtained from the composition of the layer components used. . The film strength was rubbed with a fingertip, a tissue, an eraser, and a fingertip, and visually observed. 0 was found to be damaged by the fingertip, 1 was damaged by the tissue, 2 was damaged by the eraser, and 3 was damaged by the fingertip. The sample which was not damaged by any method was designated as 4. The results are shown in Table 2.

[0048]

[Table 1]

[0049]

[Table 2]

Comparative samples (Y1 to Y2) were obtained in the same manner as in Example 1 except that the coating liquid for the low refractive index layer was replaced with a coating liquid (D1 to D2) having a constitution outside the present invention shown in Table 1. . The refractive index, luminous reflectance, and film strength of the obtained film were measured in the same manner as in Example 1 above. The results are shown in Table 2. As is clear from this example, the antireflection film of the present invention not only has excellent antireflection performance having a very low reflectance and a wide wavelength range, but also has a sufficiently strong film strength. I understand.

Example 2 (Preparation of multilayer antireflection film) (1) Coating of first layer (hard coat layer) A TAC film having a thickness of 90 μm was coated with 5% by weight of dipentaerythritol hexaacrylate and light. Polymerization initiator (trade name: Irgacure 907, manufactured by Ciba Geigy)
0.5% by weight, photosensitizer (trade name: Kaya Cure DET)
X, manufactured by Nippon Kayaku Co.) A toluene solution containing 0.2% by weight was applied to a thickness of 8 μm using a wire bar, dried, heated to 100 ° C., and a high-pressure mercury lamp of 12 W / cm was used. For 1 minute to crosslink. Then, it was allowed to cool to room temperature. The thickness of the obtained layer was 5 μm, and the refractive index was 1.535.

(2) Coating of Second Layer (High Refractive Index Layer) Separately synthesized poly (n-butyl methacrylate-co-methacrylic acid) latex (copolymer composition weight ratio: 80: 2)
0, average particle diameter 63 nm, solid content concentration 12.5% by weight:
HP1) 100 g and tin oxide fine particles (obtained from Ishihara Sangyo Co., Ltd.) 25 g were mixed, further, dipentaerythritol hexaacrylate 6 g, and a photopolymerization initiator (trade name: Irgacure 907, manufactured by Ciba Geigy) 0 .5
g, 0.2 g of a photosensitizer (trade name: Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) An emulsion liquid obtained by emulsifying and dispersing 20 g of ethyl acetate in 100 g of water using 1 g of sodium dodecylbenzenesulfonate was mixed and stirred. A coating solution was prepared.
This solution was applied on the first layer prepared above using a wire bar, and after drying, heated to 100 ° C. and 12 W
UV irradiation for 1 minute using a high pressure mercury lamp of
Then, it was allowed to cool to room temperature. The thickness of the obtained layer is 0.16
μm, and the refractive index was 1.68.

(3) Preparation of Third Layer (Low Refractive Index Layer) On the second layer prepared above, the low refractive index layers of X1 to X5, Y1, and Y2 shown in Example 1 were used as third layers. Coating and polymerization, multilayer samples ARF1 to ARF5 (the present invention), CF
1 to CF2 (Comparative Example) were produced. Table 3 also shows the evaluation results of the surface reflectance and the film strength of these samples. The evaluation method is the same as the method shown in the first embodiment.

[0054]

[Table 3]

As is clear from this example, the antireflection film of the present invention not only has excellent antireflection performance having a very low reflectance and a wide wavelength range, but also has a sufficiently strong film strength. You can see that it is.

Example 3 (Preparation of display device provided with anti-reflection film) A personal computer PC purchased from NEC Corporation with anti-reflection film X2 prepared in Example 2 above.
The sample was attached to the surface of a 9821NS / 340W liquid crystal display to prepare a display device sample, and the degree of reflection of the scenery due to the surface reflection was visually evaluated. Similarly, display device samples were prepared as anti-reflection films used in the notation method as films X3, X5, and Y2 prepared in Example 2 above. The display device provided with the anti-reflection films X2, X3, and X5 of the present invention hardly reflected the surrounding scenery and exhibited comfortable visibility, whereas the display device provided with the comparative film Y2 provided the surrounding image. And the visibility was poor.

[0057]

According to the present invention, the adhesion between particles can be improved without impairing the voids in the step of forming a film having voids by using a polymer which is coagulated and precipitated by polymerization in the process of producing a low refractive index. be able to. As a result, very good optical properties are exhibited as an anti-reflection film, and a low-cost, large-area anti-reflection film having excellent film properties such as film strength and scratch resistance can be provided in a form having suitability for production. .

[Brief description of the drawings]

FIG. 1 shows a cross-sectional view of a typical example of an antireflection film of the present invention.

FIG. 2 is a cross-sectional view of a typical example of the antireflection film of the present invention.

[Explanation of symbols]

 11, 21: low refractive index layer 12, 24: high refractive index layer 22: medium refractive index layer 13, 23: transparent film

Claims (7)

[Claims] 1. An antireflection film having at least one low refractive index layer having a microvoid having an average diameter of 200 nm or less and a refractive index of 1.45 or less and made of a fluoropolymer,
In the production process, the fluoropolymer is formed by a polymerization reaction of a monomer containing at least one corresponding fluoromonomer, and the microvoids are formed by precipitation and aggregation of the polymer generated in the polymerization process. An anti-reflection film characterized by the following. 2. The anti-reflection film according to claim 1, wherein the low refractive layer contains at least 0.1 weight fraction or more of fluorine atoms. 3. The anti-reflection film according to claim 1, wherein the low refractive index layer has a void of at least 5% by volume. 4. The antireflection film according to claim 1, wherein a solvent in which a monomer to be used is soluble and a generated polymer is insoluble is used in the process of forming the low refractive index layer. 5. The method according to claim 1, wherein the low refractive index layer is formed on a layer having a higher refractive index.
4. The anti-reflection film according to any one of items 3 to 3. 6. The haze value of the antireflection film is 3 to 3
4. The anti-reflection film according to claim 1, wherein said anti-reflection film is 0%. 7. An antireflection film having at least one low refractive index layer having a microvoid having an average diameter of 200 nm or less and having a refractive index of 1.45 or less made of a fluoropolymer,
In the production process, the fluoropolymer is formed by a polymerization reaction of a monomer containing at least one corresponding fluoromonomer, and the microvoids are formed by precipitation and aggregation of the polymer generated in the polymerization process. A display device comprising a certain anti-reflection film.