JP2003131009A - Antireflection film, optical element and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antireflection film which has a hard coat layer and an antireflection layer laminated in this order from a transparent substrate side on one side of the transparent substrate, which has antistatic effect, and which has an excellent antifouling property. SOLUTION: This is an antireflection film which has a hard coat layer and an antireflection layer which is made of a material whose refractive index is lower than that of the hard coat layer laminated in this order from a transparent substrate side on one side of the transparent substrate. It is characterized in that the surface resistibility of the hard coat layer is 1×10<11> Ω/(square) or lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with an antireflection film used for suppressing a reduction in the visibility of a screen in a display device such as a liquid crystal display (LCD), EL, PDP, and the like. The optical element being operated. Further, the present invention relates to an image display device to which the antireflection film or the optical element is attached.

[0002]

2. Description of the Related Art A liquid crystal panel has been securing a firm position as a display by recent research and development. However, the visibility of car navigation monitors and video camera monitors, which are frequently used under bright illumination, is significantly reduced due to surface reflection. Therefore, it is becoming indispensable to perform antireflection treatment on the polarizing plate used for the liquid crystal panel, and the antireflection treatment polarizing plate is used for most of liquid crystal displays which are frequently used outdoors.

The structure of the antireflection film is usually composed of a transparent substrate as a base material / a resin layer for imparting a hard coat property / an antireflection layer having a low refractive index. In such an antireflection film, from the viewpoint of reflectance, the hard coat layer is required to have a high refractive index, and the antireflection layer is required to have a lower refractive index. As the low-refractive index material for forming the antireflection layer, a fluorine-containing compound is used from the viewpoint of low reflectance and stain resistance (difficulty of human stains such as fingerprints and sweat and easiness of wiping). There is. However, the fluorine-containing compound tends to be negatively charged due to its water repellency.
Therefore, if this is used for the low refractive index material of the antireflection layer, there is a problem that dust is likely to adhere to the antireflection layer and that the dust that adheres is difficult to wipe off.

Further, in Japanese Patent Laid-Open No. 11-326602,
A low-reflection antistatic hard coat film has been proposed in which a transparent conductive layer, a hard coat layer and a low refractive index layer are laminated in this order on a transparent substrate film. However, in this low reflection antistatic hard coat film, in addition to the hard coat layer and the low refractive index layer, a transparent conductive layer must be separately provided in order to impart an antistatic effect.

[0005]

The present invention is an antireflection film in which a hard coat layer and an antireflection layer are laminated in this order from the transparent substrate side on one surface of a transparent substrate and has an antistatic effect. However, it is an object of the present invention to provide an antireflection film having excellent antifouling property. Moreover, it aims at providing the optical element provided with the said antireflection film. Moreover, it aims at providing the display device with which the said antireflection film or the optical element is mounted.

[0006]

As a result of intensive studies to solve the above problems, the present inventors have found that the above objects can be achieved by the following antireflection film, and have completed the present invention. It was

That is, the present invention provides an antireflection film in which a hard coat layer and an antireflection layer made of a material having a refractive index lower than that of the hard coat layer are laminated on one surface of the transparent substrate in this order from the transparent substrate side. The present invention relates to an antireflection film, wherein the surface resistivity of the coat layer is 1 × 10 ¹¹ Ω / □ or less.

In the antireflection film of the present invention, a hard coat layer having a surface resistivity of 1 × 10 ¹¹ Ω / □ or less is formed to form the hard coat layer as a highly conductive layer. The antireflection film is provided with an antistatic effect and has a good antifouling property, which reduces dust adhesion and improves dust wiping property. As described above, in the present invention, since the hard coat layer is a highly conductive layer, it is not necessary to separately provide a conductive layer in addition to the hard coat layer, and the hard coat layer is easily charged and has a low refractive index antireflection. It is in contact with the layer and has an excellent antistatic effect. The lower the surface resistivity of the hard coat layer is, the more preferable it is 1 × 10 ¹⁰ Ω / □ or less,
Further, it is preferably 1 × 10 ⁹ Ω / □ or less. The surface resistivity is a value measured by a digital ultra-high resistance / micro ammeter (manufactured by Advantest Corporation) which is an electrode conforming to JIS K6911. The antireflection film of the present invention is also excellent in transparency. Generally, the light transmittance of the antireflection film is preferably 80% or more.

In the antireflection film, it is preferable that the hard coat layer is made of urethane resin. Urethane resins have good transparency, strong film strength, and excellent scratch resistance as a hard coat layer. Further, as the urethane-based resin, an ultraviolet curable resin such as urethane acrylate is preferable, and the resin coating layer can be efficiently formed by a curing treatment by a simple processing operation.

In the antireflection film, the antireflection layer is preferably formed of a fluorine-containing compound. A fluorine-containing compound is preferably used as the low refractive index material of the antireflection layer from the viewpoint of low reflectivity and antifouling property. Conventionally, when a fluorine-containing compound was used as a material for forming an antireflection layer, there was a problem in antifouling property. However, in the present invention, since the hard coat layer having high conductivity is formed as described above, the fluorine-containing compound is used. Even when the antireflection layer is formed, the antifouling property is good.

In the antireflection film, conductive fine particles may be dispersed and contained in the hard coat layer. By dispersing the conductive fine particles in the hard coat layer, the hard coat layer can be efficiently made into a highly conductive layer, and the antifouling property of the antireflection layer against charging can be improved.

In the antireflection film, the surface of the hard coat layer is preferably uneven.
By forming the surface of the hard coat layer in a concavo-convex shape, it is possible to obtain an antireflection antiglare film having a light diffusing property in addition to the antireflection effect of the antireflection function.

In the present invention, the antireflection film is
The present invention relates to an optical element provided on one side or both sides of the optical element. The antireflection film of the present invention can be used for various purposes, for example, it is used for an optical element such as a polarizing plate.

Further, the present invention relates to a display device equipped with the antireflection film or the optical element. The antireflection film and optical element of the present invention can be used for various purposes, and are provided, for example, on the outermost surface of an image display device.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a transparent substrate 1.
An antireflection film in which an antireflection layer 3 is laminated on the surface of the upper hard coat layer 2. FIG. 2 shows the hard coat layer 2
Is an example of an antireflection film in which the surface of is made uneven.
The uneven surface shape of the hard coat layer 2 is
It is formed of fine particles 4 dispersed therein. In addition,
In FIG. 1 and FIG. 2, one hard coat layer 2 is laminated on the transparent substrate 1, but a plurality of hard coat layers 2 may be provided.

The transparent substrate 1 is not particularly limited as long as it has excellent visible light transmittance (light transmittance of 90% or more) and excellent transparency (haze value of 1% or less). The transparent substrate 1 is, for example, a film made of a polyester-based polymer such as polyethylene terephthalate or polyethylene naphthalate, a cellulose-based polymer such as diacetyl cellulose or triacetyl cellulose, a polycarbonate-based polymer, a transparent polymer such as an acrylic polymer such as polymethylmethacrylate. Can be given. Also polystyrene,
Styrene-based polymers such as acrylonitrile-styrene copolymers, polyethylene, polypropylene, polyolefins having a cyclic or norbornene structure, olefin-based polymers such as ethylene-propylene copolymers, vinyl chloride-based polymers, amide-based polymers such as nylon and aromatic polyamides. There is also a film made of a transparent polymer such as a polymer. Furthermore, imide polymer, sulfone polymer,
Polyether sulfone-based polymer, polyether ether ketone-based polymer, polyphenylene sulfide-based polymer, vinyl alcohol-based polymer, vinylidene chloride-based polymer, vinyl butyral-based polymer, arylate-based polymer, polyoxymethylene-based polymer, epoxy-based polymer and the aforementioned polymers A film made of a transparent polymer such as a blended product may also be used. In particular, those having optical little birefringence are preferably used. From the viewpoint of a protective film for a polarizing plate, triacetyl cellulose, polycarbonate, acrylic polymer, cycloolefin resin, polyolefin having a norbornene structure, etc. are preferable.

The thickness of the transparent substrate 1 can be appropriately determined, but is generally about 10 to 500 μm in view of strength, workability such as handleability, and thin layer property. Especially 20-300μ
m is preferable, and 30 to 200 μm is more preferable.

The hard coat layer 2 is not particularly limited as long as it has excellent hard coat properties, has sufficient strength after film formation, and has excellent light transmittance. As the resin forming the hard coat layer 2, a thermosetting resin, a thermoplastic resin,
Examples include UV curable resins, electron beam curable resins, and two-component mixed resins. Among these, curing treatment by UV irradiation can be used to efficiently form a hard coat layer by a simple processing operation. An ultraviolet curable resin that can be used is preferable.

Examples of the ultraviolet curable resin include various resins such as polyester, acryl, urethane, amide, silicone and epoxy resins, which include ultraviolet curable monomers, oligomers and polymers. Among these, urethane type is preferable. The ultraviolet-curable resin preferably used is, for example, one having an ultraviolet-polymerizable functional group, and particularly, two or more of the functional groups,
In particular, one containing 3 to 6 acrylic monomer or oligomer components can be mentioned. Further, an ultraviolet polymerization initiator is blended with the ultraviolet curable resin.

In order to adjust the hard coat layer 2 to the predetermined surface resistivity, conductive fine particles can be dispersed. The conductive fine particles include IT
It is preferable to use O (indium oxide / tin oxide), ATO (antimony oxide / tin oxide), tin oxide, AZO (antimony oxide / zinc oxide), gold colloid, silver colloid and the like. These conductive fine particles generally have an average particle size of 0.
It is ultrafine particles of 1 μm or less, and these conductive ultrafine particles are preferably 50 to 900 parts by weight, and more preferably 1 to 100 parts by weight of the resin forming the hard coat layer.
It is preferable that the content is from 0.00 to 800 parts by weight.

The surface of the hard coat layer 2 can be made uneven to impart antiglare properties. The method for forming the uneven shape on the surface is not particularly limited, and an appropriate method can be adopted. For example, the surface of the film used to form the hard coat layer 2 may be roughened in advance by an appropriate method such as sandblasting, embossing roll, or chemical etching to give an uneven shape to the film surface.
There is a method of forming the surface of the material itself for forming the hard coat layer 2 into an uneven shape. Further, there is a method in which the hard coat layer 2 is separately applied on the hard coat layer 2 to give an uneven shape to the surface of the resin film layer by a transfer method using a mold or the like. Further, as shown in FIG. 2, there is a method in which fine particles 4 are dispersedly contained in the hard coat layer 2 to give an uneven shape. As for the method of forming the uneven shape, two or more methods may be combined to form a layer in which uneven surfaces having different states are combined. Among the methods of forming the hard coat layer 2, the method of providing the hard coat layer 2 containing the fine particles 4 dispersed therein is preferable from the viewpoint of the formability of the uneven surface.

A method of forming the hard coat layer 2 by dispersing and containing the fine particles 4 will be described. As the fine particles 4,
Transparent materials such as various metal oxides, glass, and plastics can be used without particular limitation. For example, silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide,
Inorganic fine particles that may be conductive, such as antimony oxide,
Polymethylmethacrylate, polystyrene, polyurethane, acrylic-styrene copolymer, benzoguanamine,
Examples thereof include crosslinked or uncrosslinked organic fine particles and silicone fine particles made of various polymers such as melamine and polycarbonate. Further, as the fine particles, those obtained by subjecting the above particles to gold plating to impart conductivity can be used. It should be noted that these shapes are not particularly limited, and may be bead-like spherical shapes, or may be indefinite shapes such as powder. These fine particles 4 may be used alone or in combination of two or more. The average particle size of the fine particles is 1 to 1
It is 0 μm, preferably 2 to 5 μm. Further, the fine particles may be dispersed or impregnated with ultrafine particles of a metal oxide for the purpose of controlling the refractive index or imparting conductivity. The proportion of the fine particles 4 is appropriately determined in consideration of the average particle diameter of the fine particles 4, the thickness of the hard coat layer, etc., but is generally about 1 to 20 parts by weight with respect to 100 parts by weight of the resin. Yes, and even 5
It is preferably about 15 to 15 parts by weight.

Additives such as a leveling agent, a thixotropic agent and an antistatic agent can be used for forming the hard coat layer 2. Use of a thixotropic agent is advantageous for forming protruding particles on the surface of the fine uneven structure. Examples of the thixotropic agent include silica, mica, smectite and the like having a particle size of 0.1 μm or less.

The method for forming the hard coat layer 2 is not particularly limited, and an appropriate method can be adopted. For example,
A resin (containing fine particles 4 as appropriate) is applied onto the transparent substrate 1, dried and then cured. When the fine particles 4 are contained, the hard coat layer 2 having an uneven shape on the surface is formed. The resin is applied by an appropriate method such as fan ten, die coater, casting, spin coat, fan ten metalling, and gravure.
In the coating, the resin may be diluted with a general solvent such as toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol, and ethyl alcohol, or may be directly coated without dilution. You can also Further, the thickness of the hard coat layer 2 is not particularly limited, but is about 1.5 to 8 μm,
It is particularly preferable that the thickness is 2 to 6 μm.

An antireflection layer 3 is formed on the surface of the hard coat layer 2.
Are stacked. The antireflection layer 3 is made of a material having a refractive index lower than that of the hard coat layer 2. The refractive index of the hard coat layer 2 is not particularly limited, but is usually about 1.49 to 1.70. The material of the antireflection layer 3 is not particularly limited as long as it has a lower refractive index than the hard coat layer 2. As a material for forming the antireflection layer 3, for example, a resin material such as an ultraviolet curable acrylic resin, a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in a resin, tetraethoxysilane, titanium tetraethoxide, or the like. Examples thereof include sol-gel materials using the above metal alkoxides. Further, it is preferable that each material is selected from compounds containing a fluorine group in order to impart antifouling property to the surface. From the viewpoint of scratch resistance, a low refractive index layer material containing a large amount of an inorganic component tends to be excellent, and a sol-gel material is particularly preferable. The refractive index of the antireflection layer 3 is 1.35 to 1.49.
Is preferred. The method for forming the antireflection layer 3 is not particularly limited and may be applied to the surface of the hard coat layer 2 by an appropriate method, but a simple coating method is preferable. For example, it can be formed by an appropriate method such as a doctor blade method, a gravure roll coater method, or a dipping method. The thickness of the antireflection layer 3 is not particularly limited, but it is preferably 50 to 500 nm, more preferably 50 to 200 nm.

An optical element can be bonded to the transparent substrate 1 of the antireflection film shown in FIG. 1 or 2 (not shown).

Examples of the optical element include a polarizer.
The polarizer is not particularly limited, and various kinds can be used.
Examples of the polarizer include a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, an ethylene / vinyl acetate copolymer partially saponified film, and a dichromatic dye such as iodine or a dichroic dye. Examples include polyene-oriented films such as those obtained by adsorbing a volatile substance and uniaxially stretched, polyvinyl alcohol dehydrated products, polyvinyl chloride dehydrochlorinated products, and the like. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable. The thickness of these polarizers is not particularly limited, but generally 5 to 8
It is about 0 μm.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching is produced, for example, by dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. You can If necessary, it may be immersed in an aqueous solution of boric acid, potassium iodide, or the like. If necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, it is possible to wash the stains and antiblocking agent on the surface of the polyvinyl alcohol-based film, and by swelling the polyvinyl alcohol-based film, the effect of preventing unevenness such as uneven dyeing is also obtained. is there. Stretching may be performed after dyeing with iodine, stretching while dyeing, or stretching and then dyeing with iodine. It can be stretched in an aqueous solution of boric acid or potassium iodide, or in a water bath.

The above-mentioned polarizer is usually used as a polarizing plate with a transparent protective film provided on one side or both sides. The transparent protective film is preferably one having excellent transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like. As the transparent protective film, the same material as that of the transparent substrate exemplified above is used. As the transparent protective film, a transparent protective film made of the same polymer material on the front and back sides may be used, or a transparent protective film made of different polymer materials may be used. When the antireflection film is provided on one side or both sides of the polarizer (polarizing plate), the transparent substrate of the antireflection film can also serve as the transparent protective film of the polarizer.

In addition, the surface of the transparent protective film to which the polarizer is not adhered may be a hard coat layer or may have been treated for the purpose of preventing sticking. The hard coat treatment is carried out for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film is used to form a cured film excellent in hardness and sliding characteristics with an appropriate ultraviolet curable resin such as acrylic or silicone. It can be formed by a method of adding to the surface of the. Further, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer. In addition,
The hard coat layer, the sticking prevention layer and the like can be provided on the transparent protective film itself, or can be separately provided as an optical layer separately from the transparent protective film.

As the optical element, in practical use, an optical film in which another optical element (optical layer) is laminated on the polarizing plate can be used. Although the optical layer is not particularly limited, for example, a reflection plate, a semi-transmission plate, a retardation plate (1 /
One or two or more optical layers that may be used for forming a liquid crystal display device such as a viewing angle compensation film, etc. can be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a reflecting plate or a semi-transmissive reflecting plate is further laminated on a polarizing plate, an elliptically polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on a polarizing plate, a polarizing plate A wide viewing angle polarizing plate in which a viewing angle compensation film is further laminated on the plate, or a polarizing plate in which a brightness improving film is further laminated on the polarizing plate is preferable.

The reflective polarizing plate is a polarizing plate provided with a reflective layer, and is for forming a liquid crystal display device of the type that reflects incident light from the viewing side (display side) to display. Further, there is an advantage that it is possible to omit the incorporation of a light source such as a backlight and to easily reduce the thickness of the liquid crystal display device. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of a metal or the like is attached to one surface of the polarizing plate through the transparent protective film or the like, if necessary.

Specific examples of the reflection-type polarizing plate include a transparent protective film which is mat-treated as necessary, and one side of which is provided with a foil or a vapor deposition film made of a reflective metal such as aluminum to form a reflection layer. can give.

The reflection plate may be used as a reflection sheet in which a reflection layer is provided on an appropriate film in conformity with the transparent film instead of the method of directly applying it to the transparent protective film of the polarizing plate. Since the reflective layer is usually made of a metal, the use state in which the reflective surface is covered with a transparent protective film, a polarizing plate, or the like prevents the reduction of the reflectance due to oxidation, and thus the initial reflectance is maintained for a long time. It is more preferable from the viewpoint of avoiding the additional provision of the protective layer.

The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror which reflects and transmits light on the reflective layer. The semi-transmissive polarizing plate is usually provided on the back side of the liquid crystal cell, and when the liquid crystal display device is used in a relatively bright atmosphere,
An image is displayed by reflecting incident light from the viewing side (display side), and in a relatively dark atmosphere, an image is displayed using a built-in light source such as a backlight built into the back side of the semi-transmissive polarizing plate. It is possible to form a liquid crystal display device of the type that displays That is, the semi-transmissive polarizing plate is useful for forming a liquid crystal display device of a type that can save energy for using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source in a relatively dark atmosphere. Is.

An elliptical polarizing plate or a circular polarizing plate in which a retardation plate is further laminated on the polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called ¼ wavelength plate (also called a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also called a λ / 2 plate) is usually used to change the polarization direction of linearly polarized light.

The elliptically polarizing plate compensates (prevents) coloring (blue or yellow) caused by birefringence of the liquid crystal layer of a super twisted nematic (STN) type liquid crystal display device, and is used for black and white display without the coloring. Used effectively. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can also compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed obliquely. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has a function of preventing reflection. Specific examples of the above-mentioned retarder include polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene and other polyolefins, polyarylate, and a birefringent film obtained by stretching a film made of a suitable polymer such as polyamide. And an alignment film of a liquid crystal polymer, a film in which an alignment layer of a liquid crystal polymer is supported by a film, and the like. The retardation plate may be one having an appropriate retardation according to the purpose of use, such as various wavelength plates or one for the purpose of compensating for the viewing angle and the like due to birefringence of the liquid crystal layer, and may be two or more kinds. It may be one in which retardation plates are laminated to control optical properties such as retardation.

The elliptically polarizing plate or the reflection type elliptically polarizing plate is obtained by laminating the polarizing plate or the reflection type polarizing plate and the retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can be formed by sequentially stacking them separately in the manufacturing process of a liquid crystal display device so as to form a combination of a (reflection type) polarizing plate and a retardation plate. An optical film such as a polarizing plate is excellent in quality stability and stacking workability, and has an advantage that manufacturing efficiency of a liquid crystal display device can be improved.

The viewing angle compensation film is a film for widening the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a direction slightly oblique to the screen, not perpendicular to the screen. Such a viewing angle compensating retardation plate includes, for example, a retardation film, an alignment film such as a liquid crystal polymer, or a transparent substrate on which an alignment layer such as a liquid crystal polymer is supported. A normal retardation film is a polymer film having birefringence that is uniaxially stretched in its plane direction, while a retardation plate used as a viewing angle compensation film is biaxially stretched in its plane direction. A polymer film having birefringence, a biaxially oriented film such as a polymer having birefringence in which the refractive index in the thickness direction is uniaxially stretched in the plane direction and also controlled in the thickness direction and the birefringence is controlled, Used. Examples of the obliquely oriented film include those obtained by adhering a heat-shrinkable film to a polymer film and subjecting the polymer film to stretching treatment and / or shrinking treatment under the action of the shrinkage force caused by heating, and those obtained by obliquely orienting a liquid crystal polymer. Can be mentioned. The raw material polymer of the retardation plate is the same as the polymer explained in the previous retardation plate, which prevents coloration due to the change of the viewing angle due to the phase difference due to the liquid crystal cell and enlarges the viewing angle for good viewing. An appropriate one can be used for the purpose such as.

From the standpoint of achieving a wide viewing angle for good visibility, an optically anisotropic layer composed of a liquid crystal polymer alignment layer, particularly a discotic liquid crystal polymer tilted alignment layer, was supported by a triacetyl cellulose film. An optical compensation retardation plate can be preferably used.

The polarizing plate in which the polarizing plate and the brightness enhancement film are bonded together is usually used by being provided on the back side of the liquid crystal cell. The brightness enhancement film has a property of reflecting linearly polarized light of a predetermined polarization axis or circularly polarized light of a predetermined direction when natural light is incident due to reflection from the backlight of a liquid crystal display device or the back side, and transmits other light. The polarizing plate in which the brightness enhancement film and the polarizing plate are laminated, receives light from a light source such as a backlight to obtain transmitted light in a predetermined polarization state and reflects light other than the predetermined polarization state without transmitting it. It The light reflected on the surface of the brightness enhancement film is further inverted through a reflection layer or the like provided on the back side thereof and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light in a predetermined polarization state to achieve brightness. The brightness can be improved by increasing the amount of light transmitted through the improvement film and by increasing the amount of light that can be used for liquid crystal display image display and the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is,
When light is incident from the back side of the liquid crystal cell through the polarizer without using the brightness enhancement film, almost all light with a polarization direction that does not match the polarization axis of the polarizer will enter the polarizer. It is absorbed and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, about 50% of light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display and the like is reduced accordingly, and the image becomes dark. The brightness enhancement film causes light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and then inverted through a reflection layer or the like provided behind it. The light-increasing film is made to pass only the polarized light whose polarization direction reflected and inverted between the two is such that it can pass through the polarizer. Since the light is supplied to the polarizer, light from a backlight or the like can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

The above-mentioned brightness improving film is, for example, a multilayer thin film of a dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies, transmits linearly polarized light having a predetermined polarization axis, and reflects other light. Which exhibits the properties of, such as an alignment film of a cholesteric liquid crystal polymer or a film in which the alignment liquid crystal layer is supported on a film substrate, reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate materials such as those exhibiting characteristics can be used.

Therefore, in the brightness enhancement film of the type which transmits the linearly polarized light having the predetermined polarization axis, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby suppressing the absorption loss by the polarizing plate. It can be efficiently transmitted. On the other hand, with a brightness enhancement film that drops circularly polarized light like a cholesteric liquid crystal layer, it is possible to make it enter the polarizer as it is, but from the viewpoint of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable that the light is incident on the polarizing plate. By using a ¼ wavelength plate as the retardation plate, circularly polarized light can be converted into linearly polarized light.

The retardation plate functioning as a quarter-wave plate in a wide wavelength range such as a visible light region is, for example, a retardation layer functioning as a quarter-wave plate and another retardation film for light-colored light having a wavelength of 550 nm. It can be obtained by a method of superposing a retardation layer exhibiting characteristics, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one layer or two or more retardation layers.

As for the cholesteric liquid crystal layer,
Two layers or three layers with different reflection wavelengths
By arranging the layers so as to overlap each other, it is possible to obtain an element that reflects circularly polarized light in a wide wavelength range such as a visible light region, and based on that, it is possible to obtain transmitted circularly polarized light in a wide wavelength range.

Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers, like the above-mentioned polarization separation type polarizing plate. Therefore, it may be a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above reflective polarizing plate or semi-transmissive polarizing plate is combined with a retardation plate.

The antireflection film may be laminated on the optical element, and further various optical layers may be laminated on the polarizing plate by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. Those obtained by stacking these in advance are excellent in stability of quality and assembling work, and have an advantage that the manufacturing process of a liquid crystal display device can be improved. Appropriate adhesion means such as an adhesive layer may be used for lamination. In adhering the above-mentioned polarizing plate and other optical films, the optical axes thereof can be set at an appropriate arrangement angle according to the intended retardation characteristics and the like.

At least one polarizing plate or at least one polarizing plate is used.
The antireflection film is provided on at least one surface of an optical element such as a laminated optical film, but the surface without the antireflection film is bonded to another member such as a liquid crystal cell. It is also possible to provide an adhesive layer. The pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer is not particularly limited, but for example, an acrylic polymer, a silicone-based polymer,
A polymer having a base polymer such as polyester, polyurethane, polyamide, polyether, or a fluorine-based or rubber-based polymer can be appropriately selected and used. In particular, an acrylic pressure-sensitive adhesive, which has excellent optical transparency, exhibits appropriate wettability, cohesiveness and adhesiveness, and has excellent weather resistance and heat resistance, can be preferably used.

In addition to the above, prevention of foaming phenomenon and peeling phenomenon due to moisture absorption, deterioration of optical characteristics due to difference in thermal expansion and prevention of warpage of liquid crystal cells, and further formation of a liquid crystal display device having high quality and excellent durability, etc. From this point of view, an adhesive layer having a low moisture absorption rate and excellent heat resistance is preferable.

The adhesive layer is made of, for example, a natural or synthetic resin, particularly a tackifying resin, a filler, a pigment, a coloring agent, an oxidizer made of glass fiber, glass beads, metal powder, or other inorganic powder. It may contain an additive such as an inhibitor that is added to the adhesive layer. Further, it may be an adhesive layer containing fine particles and exhibiting light diffusion property.

The adhesive layer may be attached to an optical element such as a polarizing plate or an optical film by an appropriate method. As an example thereof, a pressure-sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a single solvent or a mixture of appropriate solvents such as toluene and ethyl acetate is prepared, A method in which it is directly attached on the optical element by an appropriate development method such as a casting method or a coating method, or a method in which an adhesive layer is formed on the separator and transferred to the optical element in accordance with the above, etc. can give. The adhesive layer may be provided as a layer in which layers having different compositions or types are stacked. The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, etc., and is generally 1 to 500 μm, preferably 5 to 200 μm, and particularly 10 to 100 μm.
Is preferred.

The exposed surface of the pressure-sensitive adhesive layer is temporarily covered with a separator for the purpose of preventing its contamination until it is put into practical use. As a result, it is possible to prevent contact with the adhesive layer in the usual handling state. As a separator,
Except for the above thickness conditions, for example, a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foamed sheet or metal foil, or an appropriate thin sheet such as a laminated body thereof may be used if necessary, such as silicone-based or long-chain alkyl-based. It is possible to use an appropriate one according to the prior art, such as one coated with an appropriate release agent such as fluorine-based or molybdenum sulfide.

In the present invention, each layer such as a polarizer, a transparent protective film, an optical layer, etc. forming the above-mentioned optical element, and each layer such as an adhesive layer may be, for example, a salicylic acid ester compound, a benzophenol compound, a benzotriazole compound. Alternatively, it may be one having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as a cyanoacrylate compound or a nickel complex salt compound.

The optical element provided with the antireflection film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed in a conventional manner. That is, a liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell, an optical element, and a component such as an illumination system, if necessary, and incorporating a drive circuit. There is no particular limitation except that an element is used, and the method can be applied conventionally.
The liquid crystal cell may be of any type such as TN type, STN type, and π type.

It is possible to form an appropriate liquid crystal display device such as a liquid crystal display device in which the above-mentioned optical elements are arranged on one side or both sides of a liquid crystal cell, or a device using a backlight or a reflector for an illumination system. In that case, the optical element according to the present invention can be installed on one side or both sides of the liquid crystal cell. When optical elements are provided on both sides, they may be the same or different. further,
When forming a liquid crystal display device, appropriate components such as a diffusion plate, an anti-glare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight are formed in one layer or two layers at appropriate positions. The above can be arranged.

Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitting body (organic electroluminescent light emitting body). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminated body of such a light emitting layer and an electron injection layer formed of a perylene derivative, or a laminated body of these hole injection layer, light emitting layer, and electron injection layer is known. Has been.

In the organic EL display device, holes and electrons are injected into the organic light emitting layer by applying a voltage to the transparent electrode and the metal electrode, and energy generated by the recombination of these holes and electrons is fluorescent. It emits light based on the principle that a substance is excited and the excited fluorescent substance emits light when returning to the ground state. The mechanism of recombination in the middle is similar to that of a general diode, and as can be expected from this, the current and the emission intensity show a strong nonlinearity with rectification with respect to the applied voltage.

In the organic EL display device, at least one of the electrodes must be transparent in order to extract light emitted from the organic light emitting layer, and indium tin oxide (IT) is usually used.
A transparent electrode formed of a transparent conductor such as O) is used as an anode. On the other hand, it is important to use a substance having a small work function for the cathode in order to facilitate electron injection and increase the luminous efficiency, and a metal electrode such as Mg-Ag or Al-Li is usually used.

In the organic EL display device having such a structure, the organic light emitting layer is formed of an extremely thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, when entering from the surface of the transparent substrate during non-light emission, the light transmitted through the transparent electrode and the organic light emitting layer and reflected by the metal electrode goes out to the surface side of the transparent substrate again, when viewed from the outside, The display surface of the organic EL display device looks like a mirror surface.

In an organic EL display device including an organic electroluminescent light-emitting body having a transparent electrode on the front surface side of an organic light-emitting layer that emits light when a voltage is applied and a metal electrode on the back surface side of the organic light-emitting layer, A polarizing plate can be provided on the surface side of the electrode, and a retardation plate can be provided between the transparent electrode and the polarizing plate.

Since the retardation plate and the polarizing plate have a function of polarizing the light which is incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized from the outside by the polarization action. Especially, the phase difference plate is 1/4.
The mirror surface of the metal electrode can be completely shielded by using a wave plate and adjusting the angle between the polarization directions of the polarizing plate and the retardation plate to π / 4.

That is, of the external light incident on the organic EL display device, only the linearly polarized light component is transmitted by the polarizing plate. This linearly polarized light is generally elliptically polarized by the retardation plate, but it is circularly polarized when the retardation plate is a 1/4 wavelength plate and the polarization direction between the polarizing plate and the retardation plate is π / 4. .

This circularly polarized light passes through the transparent substrate, the transparent electrode and the organic thin film, is reflected by the metal electrode, passes through the organic thin film, the transparent electrode and the transparent substrate again, and becomes linearly polarized light again on the retardation plate. . Since this linearly polarized light is orthogonal to the polarization direction of the polarizing plate, it cannot pass through the polarizing plate. as a result,
The mirror surface of the metal electrode can be completely shielded.

[0064]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Example 1 100 parts by weight of ATO was dispersed in 100 parts by weight of a urethane acrylate resin and 3 parts by weight of an ultraviolet polymerization initiator (benzophenone), and the solid content was 40% with methyl ethyl ketone.
To prepare a solution. The methyl ethyl ketone solution was applied to a triacetyl cellulose film (thickness 80 μ
m) was coated with a wire bar, dried with a solvent, and then irradiated with ultraviolet rays using a low-pressure UV lamp to form a hard coat layer having a thickness of 5 μm. The surface resistivity of the hard coat layer is 1
It was × 10 ¹¹ Ω / □. The refractive index of the hard coat layer was 1.54.

On this hard coat layer, about 1% of solid component
The coating liquid consisting of the fluorine-based polymer (alkyltrimethoxysilane (trimethoxyperfluorosilane)) of
After coating, drying and curing, the thickness after drying is 100n
An antireflection layer was formed to a thickness of m to obtain an antireflection film. The refractive index of the antireflection layer was 1.39.

Example 2 In Example 1, the urethane acrylate resin 1 was used as the methyl ethyl ketone solution for forming the hard coat layer.
The same procedure as in Example 1 was carried out except that silica beads having an average particle diameter of 2 μm, which were gold-plated with 5 parts by weight of 00 parts by weight, were further added, and the hard coat layer having an uneven surface. Was formed. The surface resistivity of the hard coat layer was 1 × 10 ¹¹ Ω / □. The refractive index of the hard coat layer was 1.54. Then, Example 1
An antireflection layer was formed in the same manner as in 1. to obtain an antireflection film.

Example 3 The same operation as in Example 1 was carried out except that the ATO content was changed to 200 parts by weight to form a hard coat layer having an uneven surface. The surface resistivity of the hard coat layer was 1 × 10 ¹⁰ Ω / □. The refractive index of the hard coat layer was 1.56. Then, Example 1
An antireflection layer was formed in the same manner as in 1. to obtain an antireflection film.

Comparative Example 1 In Example 1, the methyl ether forming the hard coat layer was formed.
Does not contain ATO dispersedly as a chilled ketone solution
The same operation as in Example 1 was performed, except that the
A hard coat layer was formed. Surface resistance of hard coat layer
Rate is 1 × 10 ¹⁴Ω / □ or more. Also hard coat
The refractive index of the coating layer was 1.51. Then, with Example 1
Similarly, an antireflection layer is formed to obtain an antireflection film.
It was

The following evaluations were performed on the antireflection films obtained in the examples and comparative examples. The results are shown in Table 1.

(Reflectance) The total reflectance (%) was measured using a spectrophotometer with a UV2400 tilt integrating sphere manufactured by Shimadzu Corporation.

(Light Transmittance) The light transmittance (%) was measured by using a spectrophotometer equipped with a tilt integrating sphere UV2400 manufactured by Shimadzu Corporation.

(Dust wiping property) After fine dust such as dust paper is forcibly scattered on the surface of the antireflection layer of the antireflection film, the work is wiped off with a white cloth attached to cotton, and the wiping property is determined according to the following criteria. It was judged.

[0074] ◯: Most dust can be removed with one wiping operation. X: Dust remains after two or more wiping operations.

(Anti-glare property) The anti-glare property was evaluated according to the following criteria. The 60 ° glossiness is in accordance with JIS K7105-1981 (manufactured by Suga Test Instruments Co., Ltd. (digital variable angle gloss meter UG
V-5DP). ◯: Gloss at 60 ° is less than 85%. X: The gloss at 60 ° is 85% or more.

[0076]

[Table 1] As shown in the above results, the antireflection films of Examples have low reflectance and good transparency, and also have good wiping-off property (contamination resistance) even when a fluorine compound is used in the antireflection layer. Further, by making the surface of the hard coat layer uneven as in Example 2, antiglare properties can be imparted. In addition, Example 1
When the antireflection film of Example 2 was used as a protective layer (protective film) of a polarizing plate, a highly practical polarizing plate having an antireflection function, which maintained the above properties, was obtained.

[Brief description of drawings]

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

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

[Explanation of symbols]

1: transparent substrate 2: Hard coat layer 3: Antireflection layer 4: Fine particles

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/1333 505 G02F 1/1335 4F100 1/1335 G09F 9/00 309A 5G435 G09F 9/00 309 313 313 313 G02B 1/10 A (72) Inventor Tomoaki Masuda 1-2, Shimohozumi, Ibaraki-shi, Osaka F-term within Nitto Denko Corporation (reference) 2H042 BA03 BA12 BA20 2H049 BA02 BA04 BA06 BA25 BA27 BA46 BB03 BB23 BB27 BB28 BB33 BB43 BB46 BB47 BB51 BB63 BB65 BB67 BC03 BC14 BC22 2H090 HA08 HC16 HD07 JC07 JD06 2H091 FA08X FA08Z FA37X FB02 GA01 GA16 LA07 2K009 AA04 AA15 BB13 BB14 BB23 BB24 BB28 CC03 CC06 CC09 DD02 DD06 EE03 4F100 AH05C AK01A AK51B AT00A BA03 BA07 BA10C CA21B CC00B DD07B GB41 JG03 JG04C JK12B JL06 JN01A JN06C JN18C YY00C 5G435 AA03 AA09 AA16 BB05 BB12 BB 15 BB16 FF05 GG32 HH03 LL14 LL19

Claims (7)

[Claims] 1. An antireflection film in which a hard coat layer and an antireflection layer made of a material having a refractive index lower than that of the hard coat layer are laminated in this order from the transparent substrate side on one surface of the transparent substrate. An antireflection film having a surface resistivity of 1 × 10 ¹¹ Ω / □ or less. 2. The antireflection film according to claim 1, wherein the hard coat layer is formed of a urethane resin. 3. The antireflection film according to claim 1 or 2, wherein the antireflection layer is formed of a fluorine-containing compound. 4. The antireflection film according to claim 1, wherein the hard coat layer contains conductive fine particles dispersed therein. 5. The antireflection film according to claim 1, wherein the surface of the hard coat layer has an uneven shape. 6. An optical element comprising the antireflection film according to claim 1 provided on one side or both sides of the optical element. 7. An image display device equipped with the antireflection film according to claim 1 or the optical element according to claim 6.