JPH10282305A - Porous optical material, and image display device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a porous optical material having a layer of low refractive index which is excellent in mass productivity, pollution resistance, and damage resistance. SOLUTION: In an optical material having at least one fluorine-containing polymer layer which contains the fluorine atoms of >=0.10 wt.% on a transparent substrate 3, a low refractive index layer 5 has the fluorine-containing polymer layer of >=0.05 vol.% to <=0.50 vol.%, and micro voids 7 of <=2000 Å in grain size, and is <=1.45 in refractive index, and the polymer layer is formed of the porous optical material in which the micro voids 7 are formed by subliming the compound dispersed in the layer in the manufacturing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porous optical material having a low refractive index layer excellent in mass productivity, stain resistance, and scratch resistance, and an image display device using the same.

[0002]

2. Description of the Related Art Low-refractive-index optical materials are applied to, for example, an anti-reflection film for preventing a reduction in contrast due to reflection of external light from a display, a cladding of an optical waveguide requiring high light transmission, a lens, a prism, and the like. is there.

[0003] Generally known materials having a low refractive index include compounds such as magnesium fluoride (refractive index: 1.38) and organic fluorine compounds such as Cytop (produced by Asahi Kasei Corporation) (refractive index: 1.38). 34). However, when a film is formed on a substrate in order to utilize them, in the case of magnesium fluoride, means such as a physical vapor deposition method is required, which is disadvantageous in mass productivity and cost. In the case of organic fluorine compounds, the cohesive force of the fluorine compound itself was originally low, and thus the adhesion to the lower layer and the scratch resistance such as surface hardness were poor.

In order to improve these, there is a method in which ultrafine particles of magnesium fluoride or an organic fluorine compound is formed into a film together with a suitable binder or the like. And a sufficiently low refractive index cannot be expected.

In an anti-reflection film using such a low-refractive-index material, in order to have an anti-reflection function in a wavelength region such as visible light, a multilayer film in which a transparent thin film of an inorganic compound is laminated is used. Membranes have been used. While a single-layer film is effective for monochromatic light, it cannot effectively prevent reflection of light having a certain wavelength range. It becomes an effective antireflection film in the region. Therefore, a film in which three or more inorganic compounds including a MgF ₂ low refractive index layer are laminated by means such as a physical vapor deposition method has been used as a conventional antireflection film.

However, in order to form such an anti-reflection film, physical vapor deposition whose thickness is controlled with high precision is performed several times in accordance with the relationship between the refractive index and the film thickness of each layer which is optimally designed in advance. Also had to be done, which was very expensive. Further, in order to improve the stain resistance such as fingerprint adhesion and the scratch resistance, it is necessary to newly provide, for example, a layer made of a fluorine-containing resin. On the other hand, when an organic compound is used for the low-refractive-index layer, a material having a practical level, particularly from the viewpoint of scratch resistance, has not yet been obtained.

As a technique for solving the above-mentioned drawbacks, there is a method in which pores made of vacuum or gas having a size smaller than the wavelength of light are included in the layer. For example, the refractive index of an air-containing layer having a refractive index of 1 is a value between the matrix material of the layer and 1, which is the refractive index of air, so that a significant reduction in the refractive index is achieved.

[0008] For example, magazine Shin Solid Film (Th
in Solid Film) 129, 1 (198)
5). Discloses a method for producing an antireflection film having a low refractive index layer in which a SiO ₂ thin film having pores is formed on a substrate by a sol-gel method using tetraethoxysilane as a raw material.

Japanese Patent Application Laid-Open No. 3-199043 discloses that a mixed film of monomethyltriethoxysilane and polyethylene glycol is formed on glass, and the polyethylene glycol is thermally decomposed by heat treatment at 350 ° C. or eluted in ethanol. Describes that a film having better antireflection ability can be obtained.

Japanese Patent Application Laid-Open No. Hei 4-121701 discloses a method in which polyvinyl carbazole and carbon tetraiodide as a polymerization initiator are coated on a glass substrate, and after photopolymerization and curing,
Immerse in xylene to elute unreacted carbon tetraiodide,
Further, by shrinking the membrane in n-hexane,
It is described that the light transmittance of the antireflection film having air bubbles of not more than 00 ° is improved by 5 to 10%.

Japanese Patent Application Laid-Open No. 6-3501 discloses an acrylic acid derivative monomer and α,
After coating α'-azoisobutyronitrile on the substrate, it was slowly cured by electron beam irradiation, and then further heated at 110 ° C. to cure the monomer and simultaneously generate nitrogen gas to cause microbubbles to be present. It is described that the refractive index of the resin was reduced by 0.1% or less as compared with the resin having no bubbles.

However, the antireflection film having a sol-gel method low refractive index layer described in the magazine Shin Solid Film could not use a polymer support for a transparent substrate because it required high-temperature baking. In addition, as a process for imparting porosity, an HF aqueous solution that is dangerous to the human body must be handled.
Not only is the manufacturing process complicated and mass production is inferior, but also there are environmental problems. Furthermore, the membrane by the sol-gel method is
For example, a layer made of a fluorine-containing resin needs to be newly provided thereon to improve the stain resistance such as fingerprint adhesion.

The anti-reflection coating described in Japanese Patent Application Laid-Open No. 3-199043 has a problem of environmental problems in the anti-reflection coating formed by the sol-gel method, but it is 350 ° C.
The thermal decomposition step by heat treatment and the step of elution into ethanol are complicated and inferior in mass productivity, and the above-mentioned problem of stain resistance has not been solved.

The anti-reflection coating described in Japanese Patent Application Laid-Open No. 4-121701 is complicated in two solvent immersion steps, is inferior in mass productivity, and takes into consideration the stain resistance and scratch resistance of the polymer constituting the matrix. There was no problem.

The low-refractive-index optical material described in JP-A-6-3501 controls the generation of nitrogen gas from α, α'-azoisobutyronitrile with high precision in order to control the size and amount of pores. It was difficult to reduce the refractive index sufficiently. In addition, there is a problem that contamination resistance and scratch resistance of the polymer constituting the matrix are not considered.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object a simple method to provide a low refractive index layer excellent in contamination resistance and scratch resistance which has not been obtained in the past. An object of the present invention is to provide a porous optical material and an image display device using the same.

[0017]

As a result of research to achieve the above object, the following method has been achieved.

1. At least one layer of 0.1 on a transparent substrate
In an optical material having a fluorine-containing polymer layer containing 0 weight fraction or more of fluorine atoms, the fluorine-containing polymer layer has a volume fraction of 0.05 volume fraction or more and 0.50 volume fraction or less.
A low-refractive-index layer having a refractive index of 1.45 or less having microvoids of 000 ° or less, wherein the microvoids are formed by sublimating a compound dispersed in the layer in a manufacturing process. material. 2. The porous optical material according to claim 1, wherein the fluorine-containing polymer layer contains at least one non-fluoropolymer or a curable compound. 3. The porous optical material according to claim 1, wherein the fluoropolymer layer contains at least one lubricant. 4. The porous optical material according to claim 1, further comprising a lubricating layer having a thickness of 50 nm or less and made of at least one lubricant on the fluoropolymer layer. 5. The porous optical material as described in any one of the above items 1 to 4, wherein the porous optical material has an antiglare ability having a haze value of 2.0 or more and 40.0 or less. 6. An image display device comprising the porous optical material according to 1 above.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The fact that the porous optical material of the present invention achieves a low refractive index with excellent contamination resistance and scratch resistance, which has not been achieved conventionally, is explained as follows.

FIG. 1 shows an optical material comprising a porous fluoropolymer layer. In the figure, 1 is a porous optical material according to the present invention, 3 is a transparent substrate such as glass or a transparent polymer support, and 5 is a fluorine-containing polymer 6 having a refractive index n1 in a gas such as vacuum or air. This is a layer in which microvoids 7 having a particle size of 2000 ° or less are dispersed.

The transparent substrate for forming the porous optical material of the present invention is not particularly limited as long as it is transparent. For example, in addition to glass and the like, cellulose derivatives (eg, di-acetyl, tri-acetyl, propionyl-, butanoyl) −,
Acetylpropionyl-acetate), polyamide,
Polycarbonates described in U.S. Pat. No. 3,023,101 and polyesters described in JP-B-48-40414 (especially polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, poly-1,
4-cyclohexane dimethylene terephthalate, polyethylene 1,2-diphenoxyethane-4,4'-dicarboxylate), polystyrene, polypropylene, polyethylene, polymethylpentene, polycarbonate,
Various transparent resins such as polymethyl methacrylate, non-tactic polystyrene, polysulfone, polyethersulfone, polyarylate, polyolefin, polyetheretherketone, polyetherimide, polyoxyethylene, and the like can be used. In particular, triacetylcellulose (TAC) , Polycarbonate and polyethylene terephthalate are preferably used.

The fluoropolymer used in the fluoropolymer layer of the present invention is not particularly limited as long as the weight fraction of fluorine atoms in the constituent units is 0.10 or more. Specific examples of the monomer unit include, for example, fluoroolefins (eg, fluoroethylene, vinylidene fluoride,
Tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, etc.), partially or fully fluorinated alkyl ester derivatives of (meth) acrylic acid,
Fully or partially fluorinated vinyl ethers and the like, and a desired polymer can be obtained by copolymerizing one or more of these monomers in an arbitrary ratio.

The fluorine-containing polymer layer of the present invention includes not only a polymer having the above-mentioned fluorine-containing monomer as a structural unit, but also a
A copolymer with a monomer containing no fluorine atom may be used. There is no particular limitation on the monomer units that can be used in combination,
For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylates (methyl acrylate, methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate), methacrylates (methyl methacrylate) , Ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyltoluene, α-methylstyrene, etc.), vinyl ethers (methyl vinyl ether, etc.),
Vinyl esters (vinyl acetate, vinyl propionate,
Vinyl cinnamate), acrylamides (such as N-tertbutylacrylamide and N-cyclohexylacrylamide), methacrylamides, and acrylonitrile derivatives.

In order to improve the scratch resistance of the fluoropolymer layer of the present invention by making the layer flexible or hard, a polymer having no at least one arbitrary fluorine atom is used. Any curable compound such as a non-fluorine polymer) or a monomer may be added. The non-fluorinated polymer is not particularly limited. For example, polyolefins (polyethylene, polypropylene, polyisoprene, polyvinyl chloride, polyvinylidene chloride, etc.), polyacrylates (polymethyl acrylate, polymethyl acrylate, polyethyl acrylate) , Polyethyl acrylate), polymethacrylates (polymethyl methacrylate, polyethyl methacrylate, polybutyl methacrylate, etc.), polystyrene derivatives (polystyrene,
Polyvinyl toluene, poly (α-methylstyrene)
And the like, polyvinyl ethers (such as polymethyl vinyl ether), polyvinyl esters (such as polyvinyl acetate, polyvinyl propionate, and polyvinyl cinnamate), and polyacrylonitrile derivatives. The curable compound is not particularly limited. For example, the above-mentioned monomers and polyfunctional (meth) acrylates (pentaerythritol tetra (meth) acrylate, pentaerythritol hexa (meth) acrylate, dipentaerythritol tetra (meth) acrylate, Pentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, etc.), epoxy compounds ((poly) ethylene glycol diglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, resorcin diglycidyl ether, etc.) , A silicon compound (tetraethoxysilane, monomethyltriethoxysilane, dimethyldiethoxysilane, etc.), or an arbitrary crosslinkable group (for example, isocyanate group, Lock isocyanate group, an epoxy group,
Polymers having an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group, or an active methylene group) can be exemplified.

At least one optional lubricant may be added to the fluorine-containing polymer layer of the present invention in order to impart lubricity to the surface and improve scratch resistance. The lubricant is not particularly limited. For example, polyorganosiloxanes such as silicone oil (polydimethylsiloxane, polydiethylsiloxane, polydiphenylsiloxane, polymethylphenylsiloxane, alkyl-modified polydimethylsiloxane, etc.), natural wax (carnauba wax, Candelilla wax, jojoba oil, rice wax, wood wax, beeswax, lanolin, whale wax, montan wax), petroleum wax (paraffin wax, microcrystalline wax, etc.), or polyethylene wax, Fischer-Tropsch wax, or high-grade synthetic wax Fatty acid amides (stearic acid amide, oleic acid amide,
N, N'-methylenebisstearic acid amide, etc.), higher fatty acid esters (methyl stearate, butyl stearate, glycerin monostearate, sorbitan monooleate, etc.), higher fatty acid metal salts (zinc stearate, etc.), Fluorinated lubricants represented by the formula (linear perfluoropolyether, side chain perfluoropolyether, etc.) and derivatives thereof (alcohol-modified perfluoropolyether, isocyanate-modified perfluoropolyether, etc.) and the like. Can be.

In the present invention, in order to improve the scratch resistance by imparting a slipperiness to the surface, a film thickness of at least one of the above lubricants on the fluorine-containing polymer layer is used.
A lubricating layer having a thickness of nm or less may be provided. The lubricant layer may be used in combination with a suitable polymer or the like to impart film forming properties. The thickness of the lubricant layer must be sufficiently smaller than the wavelength of light so as not to affect the reflection characteristics of the porous fluoropolymer layer in the present invention. Therefore, the thickness is preferably 10 nm or less. Further, since the surface needs to be completely covered with at least a monolayer of a lubricant, the film thickness is preferably 2 nm or more.

In the present invention, the fluorine-containing polymer layer has a thickness of 0.1.
It comprises at least 10 parts by weight, preferably at least 0.25 parts by weight of fluorine atoms. The weight fraction of fluorine atoms is calculated as the weight fraction of fluorine atoms in the constituent units of the fluorine-containing polymer, and in the case of a copolymer with a monomer containing no fluorine, calculated according to the copolymerization ratio of the constituent units, When the composition contains a curable compound or a lubricant, it is calculated according to the weight ratio of the materials constituting the layer.

In the present invention, the microvoids are obtained by dissolving or dispersing a sublimable compound in water or a liquid obtained by dissolving or dispersing the compound constituting the fluorine-containing polymer layer in water or an optional organic solvent, and forming a coating liquid on the transparent substrate. Applied on,
The dried film is cured by using UV light or the like, if necessary, and is further formed by sublimating the sublimable compound remaining in the film by heating or vacuum drying.

The conventional elution step requires a drying step after passing through an elution tank to remove the compound.
In addition, the same step needs to be performed two or more times to control the swelling of the layer, which is extremely complicated.

However, in the sublimation step of the present invention, the compound can be removed only by heating or vacuum drying as a sublimation zone, and the degree of vacuum which is a problem at that time does not necessarily have to be so high. In addition, since there is no problem of swelling, a porous layer with high accuracy can be mass-produced by a simple process.

The sublimable compound used in the present invention is not particularly limited, and examples thereof include well-known naphthalene and camphor. In the phase diagram of the compound,
Most exhibit sublimability under low pressure, such as ε-caprolactam, salicylic acid, oxalic acid, nitroaniline,
Nitrophenol, p-benzoquinone and the like can be mentioned, and a suitable one is selected depending on the temperature and the pressure during the sublimation step.

The microvoids thus formed have a particle size of 2000 ° or less, preferably 1000 ° or less, more preferably 500 ° or less in order not to scatter visible light. The particle size can be controlled by the particle size of the sublimable compound or the soluble compound in the coating solution in the coating solution, the drying temperature at the time of film formation, and the compatibility with the polymer serving as the matrix.

The refractive index of the porous fluorine-containing polymer layer in the present invention is 1.45 or less, and is given by the following formula based on the refractive index and volume fraction of the matrix constituting compound and the volume fraction of microvoids. According to this, as the volume fraction of the microvoids increases, the refractive index of the layer decreases, but on the contrary, the film strength deteriorates, so that the volume fraction cannot be too large, so that From 0.05 volume fraction to 0.50 volume fraction, preferably from 0.10 volume fraction to 0.25 volume fraction.

[0034]

(Equation 1)

Such a porous fluoropolymer low refractive index layer can be used as an antireflection film. FIG. 2 shows an antireflection film according to the present invention. In the figure, 2 is an antireflection film according to the present invention, 3 is a transparent substrate such as glass or a transparent polymer support, 4 is a high refractive index layer having a refractive index higher than that of the substrate, and 5 is porous It is a fluorine-containing polymer layer.

Obtaining an effective antireflection film in a wider wavelength range by forming a multilayer is based on the same principle as in the prior art. For example, JP-A-59-
As shown in Japanese Patent No. 50401, in a two-layer film,
By making the refractive index n ₁ and the thickness d ₁ of the film of the first layer in contact with the base material and the refractive index n ₂ and the thickness d _{2 of} the second layer in contact with the first layer satisfy the relationship of the following formula: In addition, the function as an antireflection film is optimized. The antireflection conditions for such a multilayer film have been known for a long time.

[0037]

(Equation 2)

The transparent substrate on which the antireflection film of the present invention is formed is, for example, glass or the like, a transparent polymer support, or the like, like the transparent substrate used for the porous optical material.

The following materials are used as the material of the high refractive index layer. As the organic material, a film-forming substance having a relatively high refractive index, for example, polystyrene, polystyrene copolymer, polycarbonate, various kinds of polycyclic compounds having an aromatic ring other than polystyrene, a heterocyclic ring, an alicyclic group, or a halogen group other than fluorine. Coalescing composition, melamine resin,
Various thermosetting resin-forming compositions using a phenolic resin or an epoxy resin as a curing agent, an alicyclic or aromatic isocyanate and / or a urethane-forming composition comprising these and a polyol, and a double bond to the above compound A composition containing various modified resins or prepolymers that have been made radically curable by introducing a compound is preferably used. In addition, as the organic material in which the inorganic fine particles are dispersed, a material having a lower refractive index than that in the case where the organic material is used alone is generally used because the inorganic fine particles have a high refractive index. In addition to the organic materials described above, acrylic-based vinyl copolymers, polyester (including alkyd) -based polymers, cellulose-based polymers, urethane-based polymers, and various curing agents for curing these, curing Various organic materials that are transparent and can stably disperse inorganic fine particles, such as a composition having a functional functional group, can be used. Further, an organic-substituted silicon-based compound can be included therein.

These silicon compounds have the general formula R _1a R _2b SiX _{4- (a + b)} (where R ₁ and R ₂ are an alkyl group, an alkenyl group,
Allyl group, or halogen group, epoxy group, amino group,
Hydrocarbon groups having a mercapto group, a methacryloxy group or a cyano group. X is a hydrolyzable substituent selected from alkoxyl, alkoxyalkoxyl, halogen and acyloxy groups. a and b are each 0, 1, or 2, and a + b is 1 or 2. ) Or a hydrolysis product thereof.

As the inorganic compound dispersed therein, oxides of metal elements such as aluminum, titanium, zirconium and antimony are preferably used. These may be provided in finely divided form as a powder or as a colloidal dispersion in water and / or other solvents. These are mixed and dispersed in the above organic material or organosilicon compound.

Examples of the inorganic material which is film-forming and can be dispersed in a solvent or is itself a liquid include alkoxides of various elements, salts of organic acids, and coordination compounds bonded to coordination compounds. Examples include titanium tetraethoxide, titanium tetra-i-propoxide, titanium tetra-n-propoxide, titanium tetra-n-butoxide,
Titanium tetra-sec-butoxide, titanium tetra-t
ert-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 tetra-sec-butoxide, zirconium tetra-tert-butoxide and other metal alcoholate compounds, further di-isopropoxytitanium bisacetylacetonate, di-butoxytitanium bisacetylacetonate, di- -Ethoxy titanium bisacetylacetonate, bisacetylacetone zirconium, aluminum acetylacetonate, aluminum di-n-butoxy Chelating compounds such as monoethyl acetoacetate, aluminum di-i-propoxide monomethyl acetoacetate, and tri-n-butoxide zirconium monoethyl acetoacetate; and active inorganic polymers mainly containing ammonium zirconium carbonate or zirconium. be able to. In addition to the above, various alkyl silicates or hydrolysates thereof, finely divided silica, particularly silica gel dispersed in a colloidal form are used as those which have a relatively low refractive index but can be used in combination with the above compounds.

On the surface of the antireflection layer of the present invention, irregularities obtained by fine particles of an organic or inorganic compound can be formed to provide an antiglare effect for preventing external reflection of scenery by irregularly reflecting external light.

The haze of the antireflection film having the antiglare effect is from 2 to 40, preferably from 1 to 10. The haze is measured by a haze meter (manufactured by Nippon Denshoku Industries) as a percentage of transmitted scattered light to transmitted linear light when light from a light source passes through the film.

The anti-reflection film may be used alone or in combination with an anti-glare effect, such as a liquid crystal display (LCD), a plasma display (PDP), an electroluminescence display (ELD), and a cathode ray tube display (CR).
By applying the present invention to an image display device such as T) and preventing reflection of external light, visibility can be significantly improved.

The antireflection layer of the present invention may be provided with a hard coat layer, a moisture-proof, antistatic layer and the like as an intermediate layer. The material used for the hard coat layer is not particularly limited. For example, a film made of a silicon-based compound or the like is used in addition to an acrylic polymer, a urethane polymer, and an epoxy polymer.

The antistatic agent used in the layer containing an antistatic agent for imparting antistatic properties is not particularly limited as long as it is generally a substance capable of imparting conductivity, and may be a hygroscopic substance or a water-soluble inorganic salt. , An ionic conductive polymer or latex, an electron conductive polymer or latex such as polyacetylene, polyaniline, or polythiophene, an ionic surfactant, a conductive metal oxide, colloidal silica, or metal particles. Of these, ionic polymers or latexes and conductive metal oxides are preferred because of their low antistatic ability and little coloring. Furthermore, a conductive metal oxide is particularly preferable because the antistatic property is not deactivated after development and the humidity dependency is not so high.

Each of the above-mentioned layers is formed by a well-known coating method, for example, a dip coating method, an air knife coating method,
Curtain coating method, roller coating method, wire bar coating method, gravure coating method, or US Patent No. 2,6
It can be applied by an extrusion coating method using a hopper described in JP-A-81,294 or the like. When several layers are applied simultaneously in one step, one or a combination of these application methods can be applied sequentially. Also, if necessary, US Pat.
No. 1,791, No. 3,508,947, No. 2,94
Nos. 1,898 and 3,526,528, and Yuji Harazaki, "Coating Engineering", p. 253 (published by Asakura Shoten in 1973). Two or more layers can be simultaneously coated.

[0049]

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 A homopolymer (refractive index) of 1% by weight of hexafluoroisopropyl methacrylate (trade name: Biscoat 6FM (manufactured by Osaka Organic Chemicals, containing 0.48% by weight of fluorine atoms) on a 90 μm TAC film) A methyl ethyl ketone (hereinafter, MEK) solution containing 0.1380% by weight and camphor at 0.1% by weight was applied at room temperature using a spin coater, and dried at 70 ° C. for 10 minutes to form a film having a thickness of 100 nm. . Then, at 80 ° C., 0.2 Torr
Was dried in vacuo to sublimate camphor to obtain a porous fluorine-containing polymer layer having a fluorine atom content of 0.48% by weight.

Example 2 A copolymer obtained by copolymerizing 2.5% by weight of hexafluoroisopropyl methacrylate and glycidyl methacrylate at a weight ratio of 8: 2 (refractive index = 1.409) on a 90 μm TAC film and 0.25% A MEK solution containing camphor by weight was applied at room temperature using a bar coater and dried at 70 ° C. for 5 minutes to form a film having a thickness of 100 nm. Thereafter, it was further dried at 80 ° C. under a vacuum of 0.2 Torr to sublimate camphor to obtain a fluorine atom content of 0.1%.
A 38% by weight porous fluoropolymer layer was obtained.

Example 3 2.0% by weight of the copolymer of Example 2 and 0.5% by weight of dipentaerythritol hexaacrylate and 0.00%
5% by weight of a photopolymerization initiator (trade name: Irgacure 907)
An MEK solution containing 0.001% by weight of a photosensitizer (trade name: Kayacure-DETX (manufactured by Nippon Kayaku)) and 0.5% by weight of camphor was added to 90 μl of a 90 μm solution.
m on a TAC film at room temperature using a bar coater, dried at 70 ° C. for 5 minutes, and immediately irradiated with UV for 1 minute using a 12 W / cm high-pressure mercury lamp, and crosslinked to form a film having a thickness of 1 μm.
A 00 nm coating was formed. Thereafter, the resultant was further dried under vacuum at 80 ° C. at 0.2 Torr to sublimate camphor to obtain a porous fluorine-containing polymer layer having a fluorine atom content of 0.31% by weight.

Example 4 2.0% by weight of 2- (perfluorodecyl) ethyl methacrylate (trade name: M-2020 (manufactured by Daikin);
A copolymer latex (refractive index = 1.397) obtained by emulsion polymerization of 0.63 weight fraction of fluorine atom (containing fluorine atom) and glycidyl methacrylate at a weight ratio of 8: 2, 0.5 weight% of polyglycerol polyglycidyl ether and photocation An aqueous dispersion containing 0.005% by weight of diphenyliodonium hexafluorophosphate and 0.25% by weight of camphor as a polymerization initiator was prepared. Camphor was added as an ethanol solution. This coating solution was added to a 90 μm TA
Coating on C film using bar coater at room temperature, 7
After drying at 0 ° C. for 10 minutes, UV irradiation was immediately performed using a 12 W / cm high-pressure mercury lamp for 30 seconds, followed by crosslinking to form a film having a thickness of 100 μm.
nm was formed. Thereafter, at 60 ° C., 0.2
The camphor was sublimated by vacuum drying at Torr to obtain a porous fluorine-containing polymer layer having a fluorine atom content of 0.40% by weight.

Example 5 Carnauba wax (trade name: purified carnauba No. 1 (manufactured by Cera Rica Noda)) 0.3 was added to the coating solution of Example 4.
An aqueous dispersion was prepared so as to be 75% by weight. Carnauba wax was heated at 90 ° C using a high-pressure homogenizer.
Dispersed at 200 kgf / cm ² , solid content concentration 10% by weight
Was prepared and added. 90 μl of this coating solution
m on a TAC film at room temperature using a bar coater, dried at 70 ° C. for 10 minutes, and immediately 12 W / cm
For 30 seconds using a high-pressure mercury lamp, and crosslinked to form a film having a thickness of 100 nm. Thereafter, the resultant was further vacuum-dried at 60 ° C. and 0.2 Torr to sublimate camphor to obtain a porous fluorine-containing polymer layer having a fluorine atom content of 0.34% by weight.

Example 6 A perfluoropolyether lubricant (trade name: FOM) was placed on the fluorine-containing polymer layer before vacuum drying in Example 3.
BLIN Z DIAC (manufactured by Ausimont))
nm film and then 0.2 Torr at 60 ° C.
Was dried under vacuum to sublimate camphor to obtain a porous fluoropolymer layer.

Example 7 [Preparation of antireflection film] (1) Preparation of antistatic conductive fine particles In an ethanol solution containing 7% by weight of stannic chloride hydrate and 0.7% by weight of antimony trichloride. A 1N aqueous solution of sodium hydroxide was added dropwise until the pH reached 3, to obtain a coprecipitate of colloidal stannic oxide and antimony oxide. The obtained precipitate was left at 50 ° C. for 24 hours to obtain a red-brown colloidal precipitate. Further water is added to the precipitate to remove excess ions,
The red-brown colloidal precipitate was washed with water by centrifugation. This colloidal precipitate was redispersed in water and a 15% by weight dispersion was sprayed into an incinerator heated to 600 ° C. to obtain a primary particle size of 0.1%.
A fine powder of tin oxide / antimony oxide composite of 005 μm was obtained. (2) Coating of hard coat layer 1% by weight of dipentaerythritol hexaacrylate and 1% by weight of urethane oligomer (trade name: UV-63)
00B (manufactured by Nippon Gohsei), 0.005% by weight of a photopolymerization initiator (trade name: Irgacure 907 (manufactured by Ciba Geigy)) and 0.001% by weight of a photosensitizer (trade name: Kayacure-DETX (Japan) The above-mentioned conductive fine particles were dispersed in a toluene solution containing the compound of Kayaku Co., Ltd.) in a concentration of 10% by weight with a horizontal sand mill to prepare a coating solution for a hard coat layer. This coating solution was applied to a TAC film having a thickness of 90 μm at room temperature using a bar coater, dried at 100 ° C., immediately irradiated with UV for 1 minute using a 12 W / cm high-pressure mercury lamp, and crosslinked to form a film having a thickness of 8 μm. Was formed. (3) Coating of High Refractive Index Layer A toluene solution containing 3% by weight of polystyrene (trade name: Toporex GPPS525-51 (manufactured by Mitsui Toatsu)) was applied on the hard coat layer using a bar coater. A high refractive index layer having a refractive index of 1.585 and a thickness of 160 nm was formed.

(4) Coating of Low Refractive Index Layer The MEK coating solution described in Example 3 was applied at room temperature using a bar coater, dried at 70 ° C. for 5 minutes, and immediately heated to 12 W
UV irradiation was performed for 1 minute using a high-pressure mercury lamp of 1 cm / cm and crosslinked to form a low refractive index layer having a thickness of 100 nm. At this point, since no microvoid was formed, the refractive index was 1.411. (5) Application of Lubricant Layer The lubricant layer described in Example 6 was formed on the low refractive index layer. (6) Formation of microvoids The above optical material was vacuum-dried at 60 ° C. and 0.2 Torr to sublimate camphor to obtain an antireflection film having a porous fluoropolymer layer.

Example 8 [Preparation of Anti-Glare Anti-Reflection Film] On a polarizing plate (trade name: Sumikaran AG2, haze: 9% (manufactured by Sumitomo Chemical Co., Ltd.)) on which a TAC film surface was subjected to anti-glare treatment.
The antireflection film having the antistatic layer, the high refractive index layer, the low refractive index layer, and the lubricant layer described in Example 7 was formed.

Example 9 The polarizing plate having the anti-glare treated anti-reflection film described in Example 8 was assembled on the surface side of a liquid crystal display (LCD).

Comparative Example 1 On a 90 μm TAC film, 2.5% by weight of perfluoro-2,2-dimethyl-1,3-dioxole (trade name: Teflon AF (manufactured by DuPont), refractive index = 1.2)
A Fluorinert FC-75 (manufactured by Sumitomo 3M) solution containing 9) was applied at room temperature using a bar coater and dried at 100 ° C. for 5 minutes to obtain a fluoropolymer layer having a thickness of 100 nm.

Comparative Example 2 2.5% by weight of hexafluoroisopropyl methacrylate (trade name: Biscoat 6FM, manufactured by Osaka Organic Chemicals, containing 0.48% by weight of fluorine atom) and glycidyl methacrylate were placed on a 90 μm TAC film. And a copolymer having a weight ratio of 5: 5 (refractive index = 1.453)
Was applied at room temperature using a bar coater and dried at 70 ° C. for 5 minutes to form a film having a thickness of 100 nm to obtain a fluorine-containing polymer layer having a fluorine atom content of 0.24% by weight. .

Comparative Example 3 A copolymer obtained by copolymerizing 2.5% by weight of methyl methacrylate and glycidyl methacrylate at a weight ratio of 5: 5 on a 90 μm TAC film (refractive index = 1.508)
And a MEK solution containing 0.25% by weight of camphor were applied using a bar coater at room temperature, and dried at 70 ° C. for 5 minutes.
A film having a thickness of 100 nm is formed, and then, at 60 ° C.
Vacuum drying was performed at 2 Torr to sublimate camphor to obtain a porous non-fluorinated polymer layer.

[Evaluation and Results] The following items were evaluated for the optical materials prepared as described above. (1) Refractive index measurement The refractive index n of the layer is determined by the reflectance R and the refractive index n of the transparent substrate.
_{It was calculated} from the following formula from _base .

[0064]

(Equation 3)

[0065] (2) microvoid volume fraction, the volume fraction V _mb microvoids material refractive index layer was obtained by the following equation.
Σ (n _i × V _i ) in the second item on the right side of the following equation is the refractive index of the material constituting the layer.

[0066]

(Equation 4)

(3) Evaluation of Fingerprint Adhesion As an index of stain resistance of the surface, the optical material was heated at a temperature of 25 ° C.
After humidity control at a humidity of 60% RH for 2 hours, a fingerprint was adhered to the surface of the low refractive index layer, and a state where the fingerprint was wiped off with a cleaning cloth was observed and evaluated as follows. Fingerprints can be completely wiped out ○ Fingerprints can be seen slightly △ Fingerprints can hardly be wiped out ×

(4) Evaluation of scratch resistance After humidifying the optical material at a temperature of 25 ° C. and a humidity of 60% RH for 2 hours, a sapphire needle having a tip of 0.05 mmR was vertically applied to the surface of the low refractive index layer, and a length of 10 cm was applied. Was scratched at a speed of 60 cm / min so that a continuous load of 0 to 100 g was obtained.
This sample was visually observed on a light table, and the load at which scratches began to appear was defined as the scratch strength. The larger the value, the better the scratch resistance.

(5) Evaluation of anti-reflection performance 400 to 700 n using a spectrophotometer (manufactured by JASCO)
The reflectance at an incident angle of 5 ° on the surface of the optical material on the low refractive index layer side in the wavelength region of m was measured. The lower the reflectance in a wide wavelength range, the better the antireflection performance is.

[0070]

[Table 1]

Table 1 shows the results of Examples and Comparative Examples.
Since the refractive index of the porous fluorine-containing polymer layers of Examples 1 to 6 was extremely low at 1.40 or less, and all were lower than the refractive index of the material constituting the layers,
Microvoid formation was observed. This void is considered to be less than 100 ° since no pores larger than 100 ° (0.01 μm) were observed in the transmission electron microscope. The fingerprint adhesion and scratch resistance were good. Also in the examples, the scratch resistance was improved by including a monomer unit having a glycidyl group, and further improved by adding a polyfunctional monomer and curing. When the porous fluorine-containing polymer layer was made to have slipperiness, scratch resistance was remarkably improved, and no scratch was visually observed in a load range of 0 to 100 g.

Comparative Example 1 had an extremely small refractive index of 1.29, but had extremely poor scratch resistance and fingerprint adhesion, and the entire film was wiped off at the time of wiping, and was not worthy of evaluation. Comparative Example 2 had the same scratch resistance and fingerprint adhesion as those of the present invention, but had a large refractive index of 1.455. This is due to the absence of microvoids, the refractive index of which is non-fluoropolymer polyvinyl ethyl ether (refractive index 1.454).
And so on. Comparative Example 3 had the same scratch resistance as that of the present invention, but had a large refractive index of 1.457 and was inferior in fingerprint adhesion due to a non-fluorine polymer. In order to lower the refractive index of the porous non-fluorinated polymer layer, it is conceivable to increase the microvoid volume fraction. However, if the microvoid volume fraction is too large, the layer becomes brittle. There is a limit to conversion.

As for the antireflection performance, only the antireflection films of Examples 7 and 8 are used, but they have excellent antireflection performance in the entire wavelength region of 400 to 700 nm. Further, in the liquid crystal display device of Example 9, the reflection of external light and the reflection of the background were significantly reduced by visual observation, and a display having a higher display quality as compared with a commercially available liquid crystal display device could be obtained.

[0074]

The porous optical material of the present invention can form a film having a refractive index lower than the refractive index of the material itself, and can be mass-produced as compared with the conventional low refractive index optical material. Excellent in stain resistance and scratch resistance. The anti-reflection film using the anti-reflection film exhibits excellent anti-reflection ability in a wide wavelength range. By incorporating the anti-reflection film, the image display device has high display quality with little reflection of external light and little reflection of the background. It becomes possible.

[Brief description of the drawings]

FIG. 1 shows a cross-sectional view of a porous optical material comprising a porous fluoropolymer layer of the present invention.

FIG. 2 is a cross-sectional view of an antireflection film comprising a porous fluoropolymer layer of the present invention and a layer having a higher refractive index than a substrate.

[Explanation of symbols]

 1: porous optical material 2: antireflection film 3: transparent substrate 4: high refractive index layer 5: porous fluoropolymer low refractive index layer 6: fluoropolymer 7: microvoid

Claims (6)

[Claims] 1. A transparent substrate comprising at least one layer of 0.10
In an optical material having a fluorine-containing polymer layer containing a fluorine atom at a weight fraction or more, the fluorine-containing polymer layer may have a fluorine-containing polymer layer content of 0.1% or more.
05 volume fraction or more, 0.50 volume fraction or less, particle size 200
A low-refractive-index layer having a microvoid of 0 ° or less and a refractive index of 1.45 or less, wherein the microvoid is formed by sublimating a compound dispersed in the layer in a manufacturing process. material. 2. The porous optical material according to claim 1, wherein the fluorine-containing polymer layer contains at least one non-fluorine polymer or a curable compound. 3. The porous optical material according to claim 1, wherein the fluoropolymer layer contains at least one lubricant. 4. A film having a thickness of 50 n on the fluoropolymer layer.
2. The porous optical material according to claim 1, further comprising a lubricating layer comprising at least one lubricant of m or less. 5. The anti-glare ability having a haze value of 2.0 or more and 40.0 or less.
4. The porous optical material according to item 1. 6. At least one layer of 0.10 on a transparent substrate
In an optical material having a fluorine-containing polymer layer containing a fluorine atom at a weight fraction or more, the fluorine-containing polymer layer may have a fluorine-containing polymer layer content of 0.1% or more.
05 volume fraction or more, 0.50 volume fraction or less, particle size 200
A low-refractive-index layer having a microvoid of 0 ° or less and a refractive index of 1.45 or less, wherein the microvoids are formed by sublimating a compound dispersed in the layer in a manufacturing process; An image display device comprising a high quality optical material.