JPH09288201A - Antireflection film and image display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily produce and to obtain a high antireflection effect by stacking plural numbers of fluorine-contg. polymer (fluorocarbon resin) fine particles having a specified range of average particle size while forming microvoids among the fine particles. SOLUTION: A low refractive index layer 11 comprising fine particles of a fluorocarbon resin (fluorine-contg. polymer) is formed on a transparent film (base body) 13 so that the low refractive index layer 11 consists of fluorocarbon fine particles and microvoids formed among the fine particles. In the low refractive index layer 11, at least two fine particles of fluorocarbon resin are superposed in the thickness direction to produce a microvoid between the particles. The average particle size of the fluorocarbon resin fine particles generally ranges 5 to 200nm and is preferably 5 to 50nm. The film thickness of the low refractive index layer 11 is generally 5 to 400nm, and preferably 50 to 200nm. The fluorine-contg. polymer is a crystalline polymer containing >=0.30 weight ratio of fluorine atoms, preferably 0.30 to 0.75 weight ratio.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a liquid crystal display (L).
The present invention relates to an antireflection film effective for lowering the reflectance of an image display surface of an image display device such as a CD) and an image display device having an antireflection film.

[0002]

2. Description of the Related Art Hitherto, as an antireflection film for light having a wide wavelength region such as visible light, a multilayer film in which transparent thin films of metal compounds such as metal oxides are laminated has been used. When a low refractive index single layer film is used as the antireflection film instead of the multilayer film, it is effective for monochromatic light, but the single layer film is effective reflection for light having a wide wavelength range to some extent. Has no preventive effect. In the above-mentioned multilayer film, the larger the number of stacked layers, the more effective the antireflection film is for light having a wide wavelength range. Therefore, as the conventional antireflection film, a film in which three or more layers of metal oxides or the like are laminated by means such as physical or chemical vapor deposition has been used. However, in order to form an antireflection film having a multi-layered structure, physical vapor deposition in which the film thickness is controlled with high precision is performed according to the relationship between the refractive index and the film thickness of each layer that is optimally designed in advance by the number of layers. It has to be done and is cumbersome and very expensive. Further, in order to improve scratch resistance of the surface or stain resistance such as fingerprint adhesion, it is necessary to newly provide a layer made of a fluorine-containing resin, for example.

In addition to the above-described method using a multilayer film, a method is known in which an antireflection effect is obtained by a film whose refractive index gradually changes from the interface with air in the film thickness direction. For example, in Japanese Unexamined Patent Publication No. 2-245702, SiO ₂ ultrafine particles having a refractive index intermediate between those of a glass substrate and MgF ₂ and MgF ₂ ultrafine particles are mixed and applied onto a glass substrate, and then applied from the glass substrate surface. SiO gradually toward the film surface
By decreasing the mixing ratio of ₂ to increase the mixing ratio of MgF _2, with greatly changes in the refractive index of the coating layer, the coating layer and the air, and the refractive index change at the interface between the coating layer and the glass substrate It is described that an antireflection effect can be obtained by making it gentle. The antireflection film thus formed exhibits a high antireflection effect because the change in the refractive index between the bottom surface and the glass surface is small.

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.

Further, Japanese Patent Application Laid-Open No. 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, in Japanese Unexamined Patent Publication No. 7-168006, the surface formed of air and fine particles (eg, MgF ₂ ) has an uneven upper layer (low refractive index), and only fine particles have an intermediate layer (medium refractive index). ), And an antireflection film comprising fine particles and a lower layer portion formed of a binder.

[0007] 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 films require complicated operations and skillful techniques for their preparation, and the obtained films do not have a satisfactory antireflection effect.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an antireflection film which can be easily produced and has a high antireflection effect. Another object of the present invention is to provide an image display device provided with an antireflection film which can be easily produced and exhibits a high antireflection effect.

[0009]

The present invention has an average particle size of 5
An antireflection film is characterized by including a low refractive index layer formed by stacking at least two fine particles of a fluoropolymer (that is, a fluororesin) in the range of up to 200 nm to form microvoids between the fine particles. . The preferred embodiments of the antireflection film of the present invention are as follows. 1) The fluoropolymer is a crystalline polymer. 2) The fluoropolymer contains 0.30 weight fraction or more (preferably 0.30 to 0.75) of fluorine atoms. 3) The volume fraction of microvoids in the low refractive index layer is 0.
Range of 05 to 0.50 (preferably 0.10 to 0.50
Range). 4) The low refractive index layer further contains a binder. 5) The fine particles of the fluoropolymer have a core-shell structure. 6) The fluoropolymer fine particles are treated with a silane coupling agent. 7) The fluorine-containing polymer contains a perfluoro-2,2-dimethyl-1,3-dioxole or tetrafluoroethylene homopolymer or a copolymer thereof. 8) The haze value of the antireflection film is in the range of 3 to 30%. 9) The antireflection film is a film formed by forming the low refractive index layer on a support (preferably a transparent film).

The antireflection film of the present invention comprises a low refractive index layer comprising fine particles of the above-mentioned fluoropolymer and microvoids, and two layers formed on a high refractive index layer having a refractive index higher than that. It is preferable. It is also preferable that these layers are provided on a support (preferably a transparent film). Further, the antireflection film of the present invention, a low refractive index layer comprising fine particles of the fluoropolymer and microvoids,
Formed on a high refractive index layer having a higher refractive index, and a higher refractive index layer formed on a medium refractive index layer having a lower refractive index and a higher refractive index than the low refractive index layer. It is preferably composed of three layers. It is also preferable that these layers are provided on a support (preferably a transparent film). Furthermore, the present invention has a refractive index of 1.40 or less, a layer thickness of 50 to 200 nm and a volume fraction of 0.02.
There is also an antireflective coating having a low refractive index layer with microvoids of ˜0.28.

The present invention also resides in an image display device having at least one of the above antireflection films.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The antireflection film of the present invention basically comprises a low refractive index layer formed from fine particles of a fluororesin (fluorine-containing polymer). The low refractive index layer has microvoids formed between the fine particles by stacking at least two of the above fine particles.

A typical constitutional example of the antireflection film of the present invention is shown in FIG. The low refractive index layer 11 is a transparent film (support) 1
It is formed on 3. The low refractive index layer is formed of fine particles of fluororesin and microvoids formed between the fine particles. In the low-refractive-index layer, microvoids are formed between the fine particles by overlapping at least two fine particles of the fluororesin in the film thickness direction. Therefore, the microvoids are generally uniformly arranged in the low refractive index layer. The fine particles of the fluororesin are generally melted or softened by the removal of the solvent or the heating to adhere to each other. Alternatively, when the fine particles of the fluororesin have a functional group (reactive group), the particles can be bound to each other by the reaction between the functional groups. Further, the fine particles of the fluororesin can be adhered to each other by using a very small amount of binder or silane coupling agent. The low refractive index layer is generally provided on the surface of the transparent film or the surface of the uppermost layer provided on the transparent film.

The fine particles generally have a thickness of one particle and are arranged in the plane direction to form a particle layer, and a plurality of particle layers are further stacked to form the low refractive index layer of the present invention. For this reason, the microvoids formed between the particles have almost the same size, and are therefore generally formed uniformly in the size of the voids and in the intervals thereof. The low refractive index layer of the present invention is fine particles in the microscopic state, but can be regarded as one layer in the macroscopic state.

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 fine particles of the fluororesin of the present invention is higher than the refractive index of air, which is generally 1.25 to 1.45. Between The low refractive index layer of the present invention is located between the refractive index of the air layer and the refractive index of the fine particles themselves. Therefore, the refractive index of the low refractive index layer of the present invention can be made lower than the refractive index of the material by the volume fraction of microvoids by making the fluororesin fine particles smaller.
The average particle size of the fluorine resin fine particles is generally in the range of 5 to 200 nm, preferably 5 to 50 nm. The thickness of the low refractive index layer is generally in the range of 5 to 400 nm,
200 nm is preferred.

Another typical example of the antireflection film of the present invention is shown in FIG. The high refractive index layer 22 is formed on the transparent film (support) 23, and the low refractive index layer 21 is further formed on the high refractive index layer 22. 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 conventional principle of forming a multilayer film using a metal compound.

In the antireflection film having the above two layers, the high refractive index layer 22 and the low refractive index layer 21 generally satisfy the following conditions (1) and (2), respectively. mλ / 4 × 0.7 <n ₁ d ₁ <mλ / 4 × 1.3 (1) nλ / 4 × 0.7 <n ₂ d ₂ <nλ / 4 × 1.3 (2) In the above formula, And m is a positive integer (generally 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. Represents the refractive index of the low refractive index layer, and d ₂ represents the layer thickness (nm) of the low refractive index layer.
The refractive index n ₁ of the high refractive index layer is generally at least 0.05 higher than that of the transparent film, and the refractive index n of the low refractive index layer is
₂ is generally at least 0.1 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 n ₁ of the high refractive index layer is generally 1.5 to 1.7.
In the range.

The above conditions (1) and (2) are well-known conditions, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-5040.
No. 1 publication.

Another typical example of the antireflection film of the present invention is shown in FIG. The medium refractive index layer 32 is formed on the transparent film (support) 33, the high refractive index layer 34 is formed on the medium refractive index layer 32, and the low refractive index layer 31 is further formed on the high refractive index layer 34. ing. The refractive index of the middle refractive index layer 32 is equal to
4 and the low refractive index layer 31. The antireflection film of FIG. 3 has a wider applicable wavelength range of light than the antireflection film of FIG.

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

The average particle size of the fluorine resin (fluorine-containing polymer) fine particles used in the present invention is generally in the range of 5 to 200 nm, and is 5 to 50 nm. Such fine particles are obtained, for example, from polymer latex. When the particle size of fine particles increases, the scattering on the film surface increases,
If it exceeds m, the scattered light is colored, which is not preferable. The fluorine resin used in the antireflection film of the present invention may be either crystalline or amorphous. Up to now, a crystalline fluororesin could not be used as a film of an optical material to reduce the light transmittance, but by using fine particles having a particle size sufficiently smaller than the wavelength of light, Even if it has a property, it can be used as an antireflection film without reducing the light transmittance. The fluororesin fine particles generally have a glass transition temperature (Tg) of room temperature or higher, and preferably 100 ° C or higher.
The upper limit is preferably 200 ° C or lower. If the Tg is less than room temperature, the fine particles are excessively softened and easily broken,
Therefore, the microvoids disappear and the refractive index rises. As the fluorine resin fine particles, fine particles of two or more kinds of fluorine resins having different Tg can be used. In that case, the difference in Tg is generally at least 5 ° C or higher, and preferably 20 ° C or higher.

Fluorine resin fine particles of polymer latex are
For example, a core portion containing a large amount of fluorine atoms and contributing to lowering the refractive index of the material, and a shell portion having a relatively low fluorine atom content may be used. For this reason, the shell part
The adhesion between the fine particles or between the fine particles and the lower layer can be improved. The surface of the shell may have a functional group such as an acryloyl group or an epoxy group.

Examples of the monomer forming the fluoropolymer of the present invention include compounds represented by the following general formula.

[0024]

Embedded image

However, R ¹ represents a hydrogen atom, a methyl group, or a fluorine atom, and p and n each represent a positive integer;

[0026]

Embedded image (However, n is an integer)

[0027]

Embedded image (However, x is an integer of 1 to 4)

Examples of fluororesins obtained from the above monomers are shown below.

[0029]

Embedded image

(Provided that l + m + n is 1 to 6;
Is an integer from 0 to 5, m is an integer from 1 to 4, n is an integer from 0 to 1, and R is F or CF _2.

[0031]

Embedded image

(Provided that o + p + q is 1 to 6,
o, p and q are each an integer of 0 to 5)

[0033]

[Chemical 6]

(Where R ¹ and R ² are each F or CF ₃ )

[0035]

Embedded image

[0036]

Embedded image

(However, R ¹ represents a hydrogen atom, a methyl group, or a fluorine atom, and p and n each represent a positive integer.)

[0038]

Embedded image

In the present invention, a fluororesin containing a perfluoro-2,2-dimethyl-1,3-dioxole homopolymer or a copolymer with tetrafluoroethylene has a refractive index of about 1.30. It is preferable because it is very low.

The refractive index of the fluororesin decreases almost linearly in proportion to the content of fluorine atoms, and the refractive index of the low refractive index layer further decreases as the content of microvoids increases. By increasing the contents of both of them, the refractive index of the low refractive index layer can be made sufficiently low. Therefore, the fluororesin is generally 0.30 or more by weight (preferably 0.3
0 to 0.75 weight fraction, especially 0.35 to 0.75 weight fraction), and the low refractive index layer generally contains 0.05
.About.0.50 volume fraction of microvoids, and more than 0.
A volume fraction of 10 to 0.50 is preferable, especially 0.10 to
A 0.28 volume fraction is preferred.

26% (0.26 volume fraction) of voids (microvoids) are formed between the fine particles when the fine particles having a monodisperse particle size are packed in the closest packing, and 48 when the simple cubic packing is used. Increase to%. In the actual system (low refractive index layer),
Due to the presence of some distribution of particle sizes, these values are not met. The porosity also changes depending on the conditions for forming the low-refractive index layer (that is, the method of fusing the particles together and the fusing conditions). If the content of microvoids is too high, the mechanical strength of the film is reduced, so the volume fraction of microvoids is preferably 0.50 or less. When using a very small amount of binder, the porosity changes depending on the ratio of the binder to the fine particles. If the microvoids (voids) thus formed have a size of several tens to several hundreds of nanometers (wavelength of light or less), the material is selected from the viewpoint of refractive index, and the volume of the formed microvoids. By adjusting the index, a transparent film having a desired refractive index can be formed.

When a small amount of binder is used in the low refractive index layer, it is necessary to use the minimum amount necessary to obtain close contact between the fine particles so as not to overfill the microvoids formed between the fine particles. Preferred examples of binders include water-soluble resins such as polyvinyl alcohol and polyoxyethylene;
Examples thereof include acrylic resins such as polymethyl methacrylate and polymethyl acrylate, and cellulose derivatives such as diacetyl cellulose and nitrocellulose.
When the fluororesin fine particles are an aqueous dispersion, the use of the above water-soluble resin is preferred. When the fluororesin fine particles are dispersed in an organic solvent, they are sufficiently dissolved in the solvent used, have an affinity for the fine particles and the support, and have high transparency (that is, the acrylic resin and the cellulose derivative). Is preferably used. Further, by using a binder having a polymerizing group, it is possible to carry out crosslinking by a treatment such as UV or heating after forming the fine particle layer. As the amount of the binder to be added, the minimum amount required to obtain the adhesion between the fine particles is used. The binder (eg, polyvinyl alcohol) is preferably added in an amount of 25% by weight or less, particularly 10% by weight.
% By weight or less is preferred.

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. As a material for forming a transparent film, a cellulose derivative (eg, diacetyl cellulose, triacetyl cellulose (TAC), propionyl cellulose, butyryl cellulose, acetyl propionyl cellulose and nitrocellulose), polyamide, polycarbonate (eg, US Pat. No. 3023101) Described in 1), polyester (polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, poly-1,4-cyclohexane dimethylene terephthalate, polyethylene-1,2-diphenoxyethane-4,4'-dicarboxylate and special Kosho 48-
40414, polyester, polystyrene, polyolefin (eg, polyethylene, polypropylene and polymethylpentene), polymethylmethacrylate, syndiotactic polystyrene, polysulfone,
Mention may be made of polyethersulphones, polyetherketones, polyetherimides and polyoxyethylenes. 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, generally, the low refractive index layer is at least one layer having a higher refractive index than that of the low refractive index layer (that is, the above-mentioned high refractive index layer, medium (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, since the inorganic fine particles generally have a high refractive index, a material having a lower refractive index than the organic material used alone can be used. As such material examples, in addition to the organic materials described above, vinyl-based copolymers including acrylics, polyesters, alkyd resins, cellulose-based polymers, urethane resins and various curing agents for curing these,
Various organic materials that are transparent and can stably disperse inorganic fine particles, such as a composition having a curable functional group, can be given.

Further organically substituted silicon-based compounds may be included therein. These silicon 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 halogen, epoxy, amino, mercapto, methacryloyl or cyano. Represents a substituted hydrocarbon group, X represents a hydrolyzable group selected from an alkoxyl group, an alkoxyalkoxyl group, a halogen atom and an acyloxy group, and a and b are a or b under the condition that a + b is 1 or 2. Are 0 and 1 respectively
Or 2. ) Or a hydrolysis product thereof.

Preferred inorganic compounds of the inorganic fine particles dispersed in these are oxides of metal elements such as aluminum, titanium, zirconium and antimony. These compounds are commercially available in finely divided form, ie as a powder or as 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 a material for forming a layer having a higher refractive index than the above, an inorganic material (eg, an alkoxide of various elements, a salt of an organic acid, etc.) which is film-forming and can be dispersed in a solvent or is itself liquid. Examples thereof include a coordination compound (eg, chelate compound) bound to a coordination compound and an active inorganic polymer. 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,
Examples thereof include chelate compounds such as aluminum di-i-propoxide monomethyl acetoacetate and tri-n-butoxide zirconium monoethyl acetoacetate; and active inorganic polymers containing zirconyl ammonium carbonate or zirconium as a main component. 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 antireflection film of the present invention can be treated so that the surface thereof has an antiglare function (that is, a function of scattering incident light on the surface and preventing the scenery around the film from being transferred 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 fine irregularities are formed, for example, by forming a layer containing inorganic or organic fine particles on the surface of the transparent film. Alternatively,
Fine particles having a particle size of 50 nm to 2 μm, which is different from fluororesin fine particles, are introduced into a coating liquid for forming a low refractive index layer in an amount of 0.1 to 50% by weight of the fluororesin fine particles to form the uppermost layer of the antireflection film. Irregularities may be formed on the surface. An antireflection film having an anti-glare function (that is, anti-glare treatment) is
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 a liquid crystal display device (LC
D), a plasma display (PDP), an electroluminescence display (ELD), a cathode ray tube display (CRT) or the like.
In the image display device having such an antireflection film, the reflection of incident light is prevented and the 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 may be formed, for example, by curtain flow coating or dip coating with a coating liquid (fluorine resin fine particles dispersed in water and / or an organic solvent) for forming this layer. It is formed by applying it to a transparent film or a high or medium refractive index layer by a coating method such as spin coating or roll coating, and drying.

In the present invention, a hard coat layer, a moisture-proof layer, an antistatic layer or the like can be provided on the transparent film as an intermediate layer. For the hard coat layer, silica-based materials can be used in addition to acrylic-based, urethane-based, epoxy-based polymers and / or oligomers and monomers (eg, UV-curable resin).

[0053]

【Example】

[Example 1] Trifluoroethyl acrylate (trade name: Biscoat 3F, manufactured by Osaka Organic Chemical Co., Ltd.), 0.3
Emulsion polymerization of 6 weight fraction containing fluorine atoms was performed to obtain fluorine resin fine particles (average particle diameter: 33 nm, refractive index: 1.405). A coating solution (solid content: 1% by weight) prepared by dispersing the fine particles of the fluororesin in a mixed solvent of water and methanol (water / methanol = 9/1, weight ratio) was added to triacetyl cellulose (T
AC) on the film using a spin coater
coating at a temperature of g or less and drying at that temperature to form a low-refractive index layer made of fine particles of fluororesin having a thickness of 100 nm,
An antireflection film was obtained. The refractive index of the low refractive index layer was 1.34 (containing about 0.15 volume fraction of microvoids). The refractive index (n _layer ) of the low refractive index layer was calculated from the reflectance (R) and the refractive index (n _base ) of the TAC film (transparent support) by the following formula.

[0054]

[Equation 1]

Volume fraction of microvoids in the low refractive index layer (V
_layer ) is the refractive index of the low refractive index layer (n _layer ) and TAC
It was calculated from the following formula from the refractive index (n _base ) of the film. V _layer = (n _layer -n _base ) / (1-n _base ) Furthermore, when the low refractive index layer was observed with an electron microscope, almost three fluororesin fine particles were overlapped in the film thickness direction to form microvoids. It was recognized that Antireflection film (TA
The reflectance of the C film and the low refractive index layer) is 0.98%
(For light having a wavelength of 550 nm) and was 3.75% in the case of TAC alone.

[Example 2] Hexafluoroisopropyl methacrylate (trade name: Biscoat 6FM, manufactured by Osaka Organic Chemical Co., Ltd., containing 0.48 weight fraction of fluorine atoms) was emulsion polymerized to obtain fluorine resin fine particles (average particles). Diameter: 30 nm, refractive index: 1.387) was obtained. A coating solution (solid content: 1% by weight) prepared by dispersing the fluorine resin fine particles in a mixed solvent of water and methanol (water / methanol = 9/1, weight ratio) was applied on a triacetyl cellulose (TAC) film using a spin coater. Was applied and dried at a temperature of 40 ° C. to form a low-refractive-index layer having a film thickness of 100 nm and made of fluorine resin fine particles to obtain an antireflection film. The refractive index of the low refractive index layer was 1.30 (containing about 0.23 volume fraction of microvoids). The refractive index of the low refractive index layer and the volume fraction of microvoids of the low refractive index layer were determined in the same manner as in Example 1. Further, when the low refractive index layer was observed with an electron microscope, it was confirmed that approximately three fluororesin fine particles overlapped in the film thickness direction to form microvoids. The reflectance of the antireflection film (TAC film and low refractive index layer) was 0.44% (for light having a wavelength of 550 nm), and 3.75% in the case of TAC alone.

Example 3 3% by weight of polystyrene (trade name: Topolex GPPS525) was added to a TAC film.
A toluene solution containing −51, manufactured by Mitsui Toatsu Chemicals, Inc. was applied using a spin coater and dried at room temperature to form a high refractive index layer having a refractive index of 1.585 and a film thickness of 160 nm. Then, perfluoro-2,2-dimethyl-1,3
-Emulsion polymerization of fine particles containing dioxole (PDD) and tetrafluoroethylene (TFE), and fine particles of fluororesin (average particle diameter: 30 nm, containing fluorine atom in about 0.60 weight fraction, refractive index: 1.310) Got The fluorine resin particles are mixed with a mixed solvent of water and methanol (water / methanol = 9
/ 1, weight ratio) coating liquid (solid content: 1% by weight)
Is coated on the high refractive index layer using a spin coater,
Drying at room temperature, film thickness including fluororesin particles 100nm
The low refractive index layer was formed. The refractive index of the low refractive index layer is 1.2
8 (containing about 0.10 volume fraction of microvoids). The refractive index of the low refractive index layer and the volume fraction of microvoids of the low refractive index layer were determined in the same manner as in Example 1. Further, when the low refractive index layer was observed with an electron microscope, it was confirmed that approximately three fluororesin fine particles overlapped in the film thickness direction to form microvoids. The reflectance of the antireflection film (TAC film and low refractive index layer) is 0.19% (wavelength 55
(For 0 nm light) and 3. for TAC only.
75%. Further, it has been found that the antireflection effect is equivalent to that of a conventionally used multilayer antireflection film formed by physical vapor deposition.

Example 4 25 parts by weight of dipentaerythritol penta / hexaacrylate (trade name: DPH
A, manufactured by Nippon Kayaku Co., Ltd., 25 parts by weight of urethane acrylate oligomer (trade name: UV-6300B, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 2 parts by weight of photopolymerization initiator (trade name: Irgacure-). 907, manufactured by Ciba-Geigy) and 0.5 parts by weight of a sensitizer (trade name: Kayacure-DET).
X, manufactured by Nippon Kayaku Co., Ltd., is dissolved in 50 parts by weight of methyl ethyl ketone to apply a coating solution on a TAC film using a spin coater, and then the coating film is irradiated with ultraviolet rays to form a hard coat layer (layer thickness: 5 μm). ) Was formed. A coating solution (solid content: 2% by weight, TiO ₂ / binder = 22/78, weight ratio) containing a fine dispersion of TiO ₂ and polymethylmethacrylate (refractive index: 1.48) as a binder was used for the hard coat layer. Apply using a spin coater and apply 10
It was dried at 0 ° C. to form a medium refractive index layer (refractive index: 1.62, layer thickness: 78 nm). Coating liquid containing a fine dispersion of TiO ₂ and the above binder (solid content: 2% by weight, TiO ₂ /
(Binder = 68/32, weight ratio) is applied on the medium refractive index layer using a spin coater and dried at 100 ° C. to form a high refractive index layer (refractive index: 2.00, layer thickness: 127 nm). Formed. Further, fine particles of fluororesin obtained from hexafluoroisopropyl methacrylate (average particle size: 30 nm,
Refractive index: 1.387; that is, the latex obtained in Example 2) and a binder (polyvinyl alcohol; refractive index:
1.50) to obtain a coating solution (solid content: 1% by weight;
Fluorine resin fine particles / binder = 84/16, weight ratio)
Using a spin coater on the high refractive index layer, coated at room temperature,
After drying at that temperature, a film thickness of 91
A low refractive index layer having a thickness of nm was formed to obtain an antireflection film. The refractive index of the low refractive index layer was 1.400 (containing about 0.10 volume fraction of microvoids). The refractive index of the low refractive index layer and the volume fraction of microvoids of the low refractive index layer were determined in the same manner as in Example 1. Further, when the low refractive index layer was observed with an electron microscope, it was confirmed that approximately three fluororesin fine particles overlapped in the film thickness direction to form microvoids. It has been found that the antireflection effect of the antireflection film (TAC film and low refractive index layer) is equivalent to that of a conventionally used multilayer antireflection film formed by physical vapor deposition.

Example 5 Example 3 was repeated except that the TAC film was changed to an antiglare-treated polarizing plate (trade name: Sumcalan AG2, haze: 9%, manufactured by Sumitomo Chemical Co., Ltd.). A polarizing plate with an antireflection film was produced in the same manner as in. The obtained polarizing plate was used as a liquid crystal display (LC
It was attached to D). On the display surface of the liquid crystal display device, reflection of incident light was sufficiently suppressed, the surrounding scenery was not reflected, and visibility was excellent.

[0060]

The low refractive index layer constituting the antireflection film of the present invention is formed of fluorine resin fine particles and microvoids formed between the fine particles. This low refractive index layer is a layer having a refractive index lower than that of the material, and has a very low refractive index. In particular, an antireflection film using this low refractive index layer together with at least one layer having a high refractive index exhibits a high antireflection effect.

[Brief description of drawings]

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

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

FIG. 3 shows a cross-sectional view of another typical example of the antireflection film of the present invention.

[Explanation of symbols]

 11, 21, 31 Low refractive index layer 22, 34 High refractive index layer 32 Medium refractive index layer 13, 23, 33 Transparent film

Claims (10)

[Claims] 1. A reflection comprising a low refractive index layer formed by stacking at least two fine particles of a fluoropolymer having an average particle diameter in the range of 5 to 200 nm to form microvoids between the particles. Preventive film. 2. The antireflection film according to claim 1, wherein the fluoropolymer is a crystalline polymer. 3. The antireflection film according to claim 1, wherein the fluoropolymer contains 0.30 weight percent or more of fluorine atoms. 4. The antireflection film according to claim 1, wherein the volume fraction of microvoids in the low refractive index layer is in the range of 0.05 to 0.50. 5. The antireflection film according to claim 1, wherein the low refractive index layer further contains a binder. 6. The antireflection film according to claim 1, wherein the fine particles of the fluoropolymer have a core-shell structure. 7. The antireflection film according to claim 1, wherein the fluorine-containing polymer fine particles are treated with a silane coupling agent. 8. The fluoropolymer is perfluoro-
The antireflection film according to claim 1, comprising a homopolymer of 2,2-dimethyl-1,3-dioxole or tetrafluoroethylene, or a copolymer thereof. 9. The haze value of the antireflection film is 3 to 30%.
The antireflection film according to claim 1, which is in the range of. 10. An image display device comprising the antireflection film according to claim 1.