JP2003268324A - Adhesive optical film and image display device - Google Patents

Abstract

(57) [Summary] [Problem] To provide a pressure-sensitive adhesive optical film having a pressure-sensitive adhesive layer excellent in reworkability, in which films can be firmly bonded to each other without deteriorating without impairing optical characteristics. The purpose is to do. It is another object of the present invention to provide an image display device using the adhesive optical film. The adhesive composition for forming a pressure-sensitive adhesive layer uses a pressure-sensitive adhesive composition containing a polymer having a polycarbonate structure as a base polymer. Provide an adhesive optical film having power.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an adhesive optical film having an adhesive layer laminated on one side or both sides of an optical film. Further, the present invention relates to an image display device such as a liquid crystal display device, an organic EL display device and a PDP, which uses the adhesive optical film.

[0002]

2. Description of the Related Art In a liquid crystal display device, it is essential to dispose polarizing elements on both sides of a glass substrate forming the outermost surface of the liquid crystal panel because of its image forming system. It is attached to the outermost surface. Further, on the outermost surface of the liquid crystal panel, various optical elements have been very often used in addition to the polarizing plate in order to improve the display quality. For example, a retardation plate for preventing coloration, a viewing angle widening film for improving the viewing angle, and a brightness enhancement film for enhancing the contrast are used. Such films are collectively called optical films.

When the optical film is attached to the outermost surface of a liquid crystal panel, an adhesive is usually used in order to suppress the loss due to the reflection of light at the interface. In addition, since the optical film can be instantly fixed on the outermost surface of the liquid crystal panel, and since it has advantages such as not requiring a drying step to fix the optical film, the pressure-sensitive adhesive is preliminarily formed on one side of the optical film. Is provided as. That is, an adhesive optical film is generally used to attach the optical film to the outermost surface of the liquid crystal panel.

[0004]

The characteristics required for the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive type optical film are: (1) not to impair the appearance and optical characteristics of the surface of the optical film; (2) It is possible to firmly bond the films together so that peeling does not occur, (3)
When attaching the optical film to the outermost surface of the liquid crystal panel,
It is possible to peel the optical film and re-bond (rework) again when the bonding position is wrong or a foreign substance is caught in the bonding surface.

The present invention is a pressure-sensitive adhesive type optical film in which a pressure-sensitive adhesive layer is laminated on one side or both sides of an optical film, and the films are firmly bonded to each other without deteriorating optical characteristics and peeling. An object of the present invention is to provide a pressure-sensitive adhesive type optical film having a pressure-sensitive adhesive layer that can be laminated and has excellent reworkability. Furthermore, it aims at providing the image display apparatus using this adhesive type optical film.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have selected and used a specific adhesive composition for providing an adhesive layer on an optical film. As a result, the inventors have learned that the required characteristics can be satisfied, and have completed the present invention.

That is, the present invention provides a pressure-sensitive adhesive type optical film in which a pressure-sensitive adhesive layer is provided on one side or both sides of an optical film, wherein the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer uses a polymer having a polycarbonate structure as a base polymer. And a pressure-sensitive adhesive optical film.

Further, in the pressure-sensitive adhesive type optical film in which a pressure-sensitive adhesive layer is provided on one side or both sides of the optical film,
Adhesive strength (peeling angle: 90 °, peeling speed: 3 when bonded to a polycarbonate-based stretched film using the pressure-sensitive adhesive layer
The invention relates to a pressure-sensitive adhesive type optical film using a pressure-sensitive adhesive composition having a width (00 mm / min) of 20 N / 25 mm or more.

Further, in a pressure-sensitive adhesive type optical film having a pressure-sensitive adhesive layer provided on one side or both sides of an optical film, the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer contains a polymer having a polycarbonate structure as a base polymer, Adhesive strength when adhered to polycarbonate using the pressure-sensitive adhesive layer (peel angle 90 °, peel speed 300 mm / mi
n) is 20 N / 25 mm or more in width, and relates to an adhesive optical film.

The solvent-insoluble component in the pressure-sensitive adhesive composition is 60.
It is preferably at least wt%, and the optical film constituting the pressure-sensitive adhesive optical film is preferably a polycarbonate-based stretched film.

The present invention relates to an image display device such as a liquid crystal display device, an organic EL display device and a PDP, which uses the adhesive optical film composed of the adhesive composition and the optical film as described above.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The pressure-sensitive adhesive optical film according to the present invention comprises a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition on one side or both sides of the optical film, and these pressure-sensitive adhesive optical films are laminated in two or more layers. It can also be used.
In addition, a release film layer can be provided on the pressure-sensitive adhesive layer in contact with the air interface for the purpose of protection before use.

As the pressure-sensitive adhesive composition used for the pressure-sensitive adhesive type optical film, generally used appropriate pressure-sensitive adhesive compositions such as acrylic type and epoxy type can be used. From the viewpoint of the balance characteristics of
It is preferable to use a polymer having a polycarbonate structure which is a condensation polymer as a base polymer. The polymer having the above polycarbonate structure has the following formula:

[Chemical 1] (R is a linear or branched hydrocarbon group having 2 to 20 carbon atoms) having a repeating unit represented by a weight average molecular weight of 10,000 or more, preferably 30,000 or more ( It is usually up to 300,000).

Such polymers include polyesters synthesized from polycarbonate diol (or its derivative) and dicarboxylic acid (or its derivative), polyesters synthesized from polycarbonate dicarboxylic acid and diol, and polycarbonate diol and diisocyanate. Examples of the polyurethane to be synthesized include aliphatic polyesters synthesized from a polycarbonate diol and a dicarboxylic acid.

This aliphatic polyester has a diol component containing polycarbonate diol as an essential component and 2 to 2 carbon atoms.
It is obtained by subjecting a dicarboxylic acid component essentially containing a dicarboxylic acid having an aliphatic or alicyclic hydrocarbon group of 0 as a molecular skeleton to an esterification reaction in the usual manner with or without a catalyst. It is a thing. In this reaction, it is desirable that the diol component and the dicarboxylic acid component are equimolar reaction so that the molecular weight of the obtained aliphatic polyester is in the above range, but either one of them is used in order to accelerate the esterification reaction. The reaction may be carried out using an excess amount.

The polycarbonate diol used here is a diol having a polycarbonate structure having a repeating unit represented by the above formula, and has a number average molecular weight of 400.
Or more, preferably 900 or more (usually up to 10,000).
For example, polyhexamethylene carbonate diol,
Examples include poly (3-methylpentene carbonate) diol, polypropylene carbonate diol, and mixtures and copolymers thereof. As a commercially available product, "PLACCEL CD205PL" manufactured by Daicel Chemical Industries, Ltd.,
"CD208PL", "CD210PL", "C"
D220PL "," CD205HL "," CD20 "
8HL ”,“ CD210HL ”,“ CD220H ”
L ”and the like.

As the diol component, in addition to these components, if necessary, a linear diol such as ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, decanediol, octadecanediol or a branched diol. You may use together such components. These other diols should be used in an amount of 50% by weight or less, preferably 30% by weight or less based on the total amount of the diol component. Further, if necessary, a small amount of a trifunctional or higher functional polyol component may be added in order to increase the molecular weight of the polymer.

The dicarboxylic acid component has 2 to 2 carbon atoms.
The aliphatic or alicyclic hydrocarbon group of 0 has a molecular skeleton, and the hydrocarbon group may be linear or branched. Specifically, succinic acid, methylsuccinic acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, 1,14-tetradecanedioic acid, tetrahydrophthalic acid, endomethylenetetrahydrophthalic acid, etc. Acid anhydrides and lower alkyl esters thereof.

In the present invention, usually, a polymer having a polycarbonate structure such as the above-mentioned aliphatic polyester is subjected to a cross-linking treatment by an appropriate means so that the solvent-insoluble component of the polymer component in the pressure-sensitive adhesive layer is 60% by weight or more, When the amount is preferably 70% by weight or more (usually up to 95% by weight), good results can be obtained in the balance characteristics of the adhesiveness and the reworkability.

The method for measuring the solvent-insoluble component of the polymer component in the pressure-sensitive adhesive layer is, for example, as follows. First, the adhesive is scraped off from the sample, and about 0.1 g is precisely weighed. This is immersed in toluene for 5 days, the solvent-insoluble component is taken out, dried at 130 ° C. for 2 hours, the weight thereof is determined, and the ratio (% by weight) to the weight before immersion is calculated.

The crosslinking method is not particularly limited, but as the crosslinking agent, a polyfunctional compound having a functional group capable of reacting with a hydroxyl group or a carboxyl group contained in a polymer such as an aliphatic polyester, for example, a polyisocyanate compound. A method using an epoxy compound, an aziridine compound, a metal chelate compound, a metal alkoxide compound or the like is preferable.

Among the above crosslinking agents, polyisocyanate compounds are most preferable. Specifically, ethylene diisocyanate, butylene diisocyanate, lower aliphatic polyisocyanates such as hexamethylene diisocyanate, cyclopentylene diisocyanate, cyclohexylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate, 2,4-tolylene diisocyanate And aromatic polyisocyanates such as 4,4′-diphenylmethane diisocyanate and xylylene diisocyanate. In addition, tolylene diisocyanate adduct of trimethylol propane and hexamethylene diisocyanate adduct of trimethylol propane are also preferably used.

These cross-linking agents are used alone or in a mixture of two or more kinds. The amount to be used is appropriately selected depending on the balance with the polymer such as aliphatic polyester and the purpose of using the adhesive sheet. Usually, the proportion is 1 to 10 parts by weight with respect to 100 parts by weight of a polymer such as an aliphatic polyester, which gives good results in the balance characteristics of adhesiveness and reworkability.

Various conventionally known tackifiers may be added to the pressure-sensitive adhesive composition used in the present invention as long as the required properties are not impaired. By using this tackifier, adhesiveness and heat resistance can be improved. It can be easier to balance. Further, the pressure-sensitive adhesive composition of the present invention may optionally contain various conventionally known additives such as inorganic or organic fillers, metal powders, powders such as pigments, particles and foils. it can.
Further, durability may be improved by adding various antiaging agents.

The method of forming the pressure-sensitive adhesive layer is not particularly limited, and a method of coating the pressure-sensitive adhesive composition (solution) on one side or both sides of the optical film and drying, a release film provided with a pressure-sensitive adhesive layer. And the like. The thickness (film thickness after drying) of the pressure-sensitive adhesive layer is not particularly limited, but is preferably about 10 to 40 μm.

The optical film and the pressure-sensitive adhesive layer in the present invention are treated with an ultraviolet absorber such as a salicylate compound, a benzophenol compound, a benzotriazole compound, a cyanoacrylate compound, and a nickel complex salt compound. It may be one having an ultraviolet absorbing ability by the method described above.

As the release film, an appropriate thin layer such as synthetic resin film such as polyethylene, polypropylene, polyethylene terephthalate, rubber sheet, paper, cloth, non-woven fabric, net, foamed sheet, metal foil and laminates thereof is used. be able to. In addition, the surface of the release film may be subjected to a treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment, if necessary, in order to enhance the releasability from the pressure-sensitive adhesive layer.

The type of the optical film is not particularly limited, but for example, a polarizing plate, a retardation plate,
Examples thereof include films used for forming image display devices such as an optical compensation film and a brightness enhancement film. Moreover, you may laminate | stack and use such a film. Further, according to the present invention, when a polycarbonate-based stretched film is used as the optical film, particularly strong adhesive force can be obtained, and therefore it is preferably used. This stretched polycarbonate film is preferably used mainly as a retardation plate.

Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The stretching treatment can be carried out, for example, by a roll stretching method, a long gap side stretching method, a tenter stretching method, a tubular stretching method or the like. In the case of uniaxial stretching, the stretching ratio is generally about 1.1 to 3 times. Although the thickness of the retardation plate is not particularly limited, it is generally 10 to 200 μm, preferably 20 to 100 μm.

As the polymer material, for example, polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, poly Ether sulfone, polyphenylene sulfide, polyphenylene oxide,
Examples thereof include polyallyl sulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulosic polymers, and various binary and ternary copolymers, graft copolymers, blends thereof, and the like. These polymer materials become oriented materials (stretched film) by stretching.

Polycarbonate, which is a material for a polycarbonate-based stretched film, is a polymer material having a carbonate bond formed by a polycondensation reaction, and is generally obtained from a bisphenol derivative and phosgene or diphenyl carbonate. Examples of the bisphenol derivative include 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) methane, 1,1-
Bis (4-hydroxyphenyl) cyclohexane, 9,
9-bis (4-hydroxyphenyl) fluorene, 1,
1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4
-Hydroxyphenyl) -2-phenylethane, 2,2
-Bis (4-hydroxyphenyl) -1,1,1,3
Examples thereof include 3,3-hexafluoropropane, bis (4-hydroxyphenyl) diphenylmethane, bis (4-hydroxyphenyl) sulfide, and bis (4-hydroxyphenyl) sulfone. Further, the hydrogen group of these phenyl groups may be partially substituted with a methyl group or a halogen group. These bisphenol derivatives may be used alone or in combination of two or more.
Polyester carbonate containing components such as terephthalic acid and isophthalic acid may be used as the polycarbonate.

As the liquid crystal polymer, for example, various kinds of main chain type or side chain type in which a conjugated linear atomic group (mesogen) for imparting liquid crystal orientation is introduced into the main chain or side chain of the polymer, etc. Can be given. Specific examples of the main chain type liquid crystalline polymer include a structure in which a mesogenic group is bonded by a spacer portion that imparts flexibility, such as a nematic oriented polyester liquid crystalline polymer, a discotic polymer or a cholesteric polymer. . Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin is provided through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. These liquid crystal polymers are prepared by, for example, rubbing the surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or obliquely vapor-depositing silicon oxide to develop a liquid crystal polymer solution on the orientation-treated surface. Then, heat treatment is performed.

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 the viewing angle or the like due to birefringence of the liquid crystal layer. It may be one in which at least one type of retardation plate is laminated to control optical characteristics such as retardation.

As the polarizing plate, one having a transparent protective film on one side or both sides of a polarizer is generally used.

The polarizer is not particularly limited and various kinds can be used. For example, a dichroic substance such as iodine or a dichroic dye is adsorbed onto a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or an ethylene / vinyl acetate copolymer partially saponified film. Uniaxially stretched films, polyene oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer made 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 80.
It is about μm.

A polarizer obtained by uniaxially stretching a polyvinyl alcohol film by dyeing it with iodine is prepared by, for example, immersing polyvinyl alcohol in an aqueous solution of iodine, dyeing it, and stretching it to 3 to 7 times its original length. You can If necessary, it may contain boric acid, zinc sulfate, zinc chloride or the like, and may be immersed in an aqueous solution of 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 anti-blocking agents 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.

As a material for forming the transparent protective film provided on one side or both sides of the above-mentioned polarizer, a material excellent in transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like is preferable. For example, polyester-based polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose-based polymers such as diacetyl cellulose and triacetyl cellulose, acrylic-based polymers such as polymethyl methacrylate, styrene such as polystyrene and acrylonitrile-styrene copolymer (AS resin). Examples thereof include a polymer and a polycarbonate polymer. Further, polyethylene, polypropylene, a polyolefin having a cyclo-based or norbornene structure, ethylene
A polyolefin-based polymer such as a propylene copolymer,
Vinyl chloride polymers, amide polymers such as nylon and directional polyamides, imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, polyphenylene sulfide polymers, vinyl alcohol polymers, vinylidene chloride polymers A polymer, a vinyl butyral-based polymer, an arylate-based polymer, a polyoxymethylene-based polymer, an epoxy-based polymer, a blend of the above polymers, and the like are also examples of the polymer forming the transparent protective film. The transparent protective film can also be formed as a cured layer of an acrylic, urethane-based, acrylic urethane-based, epoxy-based, silicone-based, etc. thermosetting or ultraviolet curable resin. Of these, cellulose-based polymers are preferable. Although the thickness of the transparent protective film is not particularly limited, it is generally 500 μm or less and 1 to 300.
μm is preferred. In particular, the thickness is preferably 5 to 200 μm.

The surface of the transparent protective film on which the polarizer is not adhered (the surface on which the coating layer is not provided) is subjected to a treatment for the purpose of hard coat layer, antireflection treatment, sticking prevention, diffusion or antiglare. May be

The hard coat treatment is carried out for the purpose of preventing scratches on the surface of the polarizing plate. For example, a cured film excellent in hardness and sliding characteristics made of an appropriate ultraviolet curable resin such as acrylic or silicone is transparent. It can be formed by a method of adding to the surface of the protective film.
The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the modified plate, and can be achieved by forming an antireflection film or the like according to the conventional method. Further, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer.

The anti-glare treatment is carried out for the purpose of preventing external light from being reflected on the surface of the polarizing plate and obstructing the visual recognition of the light transmitted through the polarizing plate. For example, sandblasting or embossing It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a surface roughening method or a transparent fine particle compounding method. The fine particles included in the formation of the surface fine uneven structure have, for example, an average particle diameter of 0.5 to 50 μm.
Silica, alumina, titania, zirconia, tin oxide,
Transparent fine particles such as inorganic fine particles which may be conductive, such as indium oxide, cadmium oxide, antimony oxide, etc., and organic fine particles, which are composed of a crosslinked or uncrosslinked polymer, are used. When forming the surface fine uneven structure, the amount of the fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The anti-glare layer may also serve as a diffusion layer (such as a viewing angle enlarging function) for diffusing light transmitted through the polarizing plate and enlarging the viewing angle.

The antireflection layer, the antisticking layer, the diffusion layer, the antiglare layer and the like can be provided on the transparent protective film itself, or as an optical layer separately from the transparent protective film. it can.

The treatment for adhering the polarizer and the transparent protective film is not particularly limited, but for example, an adhesive made of vinyl polymer, boric acid, borax, glutaraldehyde, melamine, oxalic acid, etc. Can be carried out via an adhesive or the like made of at least a water-soluble cross-linking agent of a vinyl alcohol polymer. The adhesive layer can be formed as a coating and drying layer of an aqueous solution, etc., but when preparing the aqueous solution, other additives and a catalyst such as an acid can be added as necessary.

The optical film of the present invention can be used mainly by laminating another optical layer on the polarizing plate in practical use. The optical layer is not particularly limited, but for example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including a wavelength plate such as 1/2 or 1/4), and a viewing angle compensation film. One or two or more optical layers that may be used can be used. In particular, a 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 enhancement 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. In addition, it is possible to omit a built-in light source such as a backlight, and it is easy to 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 metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like, if necessary.

As a specific example of the reflective polarizing plate, a transparent protective film having a matte treatment may be provided on one side with a foil or vapor deposition film made of a reflective metal such as aluminum to form a reflective layer. Can be given. Further, the transparent protective film may contain fine particles to form a finely corrugated surface structure, and a reflective layer having a finely corrugated structure formed thereon may be used. The reflective layer having the fine concavo-convex structure has the advantage that diffused incident light is diffused to prevent directivity and glare, and uneven brightness can be suppressed.
Further, the transparent protective film containing fine particles has an advantage that incident light and reflected light thereof are diffused when they pass therethrough, and uneven brightness can be further suppressed. The formation of the reflective layer having a fine concavo-convex structure that reflects the surface fine concavo-convex structure of the transparent protective film is performed by depositing a metal by an appropriate method such as a vacuum vapor deposition method, an ion plating method, a vapor deposition method such as a sputtering method, or a plating method. It can be performed by a method of directly attaching to the surface of the transparent protective layer.

The reflection plate may be used as a reflection sheet in which an appropriate film conforming to the transparent film is provided with a reflection layer in place 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 reflective surface is covered with a transparent protective film, a polarizing plate, or the like in a usage state, which prevents the reduction of the reflectance due to oxidation, and thus the long-lasting initial reflectance. Also, it is preferable in terms of avoiding the additional attachment 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 in 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 in 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 can save energy for using a light source such as a backlight in a bright atmosphere, and is useful for forming a liquid crystal display device of a type that can be used with a built-in light source even in a relatively bright 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,
As a retardation plate that changes linearly polarized light into circularly polarized light or circularly polarized light into linearly polarized light, a so-called quarter wave plate (λ
/ 4 plate) is used. Half-wave plate (λ / 2
A 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.

The elliptically polarizing plate and the reflection type elliptically polarizing plate described above are obtained by laminating a polarizing plate or a reflection type polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate,
It may be formed by sequentially laminating (reflection type) polarizing plate and retardation plate so as to form a combination thereof in the manufacturing process of the liquid crystal display device. These products are excellent in stability of quality, workability of stacking, and the like, and have an advantage that manufacturing efficiency of a liquid crystal display device or the like 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 slightly oblique direction, not perpendicular to the screen. Such a viewing angle compensating retardation plate includes, for example, a retardation plate, an alignment film of a liquid crystal polymer or the like, or a transparent substrate on which an alignment layer of a liquid crystal polymer or the like is supported. A normal retardation plate is a polymer film having birefringence uniaxially stretched in its plane direction, whereas a retardation plate used as a viewing angle compensation film is a biaxially stretched birefringence film. A polymer film having refraction, a biaxially stretched film such as a polymer or a tilt-oriented film having birefringence in which the refractive index in the thickness direction is controlled, which is uniaxially stretched in the plane direction and also stretched in the thickness direction. Is used. As an inclined orientation film,
Examples thereof include those obtained by adhering a heat-shrinkable film to a polymer film and subjecting the polymer film to a 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. 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.

A polarizing plate obtained by laminating a polarizing plate and a brightness enhancement film is usually used by being provided on the back side of a 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 a backlight of a liquid crystal display device or the back side, and transmits other light. A polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter and obtain transmitted light in a predetermined polarization state, while light other than the predetermined polarization state is reflected without being transmitted. It The light reflected on the surface of the brightness enhancement film is inverted through a reflection layer or the like provided on the rear side of the brightness enhancement film to be 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 that passes through the improvement film and by supplying polarized light that is difficult to be absorbed by the polarizer to increase the amount of light that can be used for liquid crystal image display and the like. That is, when light is incident from the back side of the liquid crystal cell through a polarizer in a backlight without using a brightness enhancement film, light having a polarization direction that does not match the polarization axis of the polarizer is almost polarized. It is absorbed by the child 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 allows light having a polarization direction that is absorbed by the polarizer to be reflected by the brightness enhancement film once without entering the polarizer, and then inverted through a reflection layer or the like provided behind it. And then re-incident on the brightness enhancement film, and the polarization direction of the light reflected and inverted between the two is such that it can pass through the polarizer. Since the light is supplied, the light from the backlight or the like can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

A diffusing plate may be provided between the brightness enhancement film and the reflective layer or the like. The light in the polarization state reflected by the brightness enhancement film is directed to the reflection layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough, and at the same time, the polarization state is eliminated and the state becomes a non-polarization state. That is, the original natural light condition is restored. The light in the non-polarized state, that is, the natural light state is directed to the reflective layer or the like, reflected through the reflective layer or the like, again passes through the diffuser plate, and re-enters the brightness enhancement film. By providing the diffusion plate that restores the original natural light state, it is possible to maintain the brightness of the display screen and at the same time reduce the unevenness of the brightness of the display screen to provide a uniform bright screen. By providing a diffuser plate that restores the original natural light state, the number of repetitions of reflection of the first incident light is moderately increased, and it is thought that it was possible to provide a uniform bright display screen together with the diffusion function of the diffuser plate. To be

The above-mentioned brightness enhancement film is, for example, a multilayer thin film of a dielectric or a multilayer laminate of thin 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 oriented film of a cholesteric liquid crystal polymer or an oriented liquid crystal layer 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 linearly polarized light of the above-mentioned predetermined polarization axis, the transmitted light is directly incident on the polarizing plate with the polarizing axis aligned, and thereby the absorption loss by the polarizing plate is suppressed. , Can be efficiently transmitted. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light like a cholesteric liquid crystal layer, it can be directly incident on a polarizer, 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. In addition,
By using a quarter wave plate as the phase difference 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 other retardation for monochromatic 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,
By combining two or more layers having different reflection wavelengths to form an arrangement structure in which two or more layers are overlapped, a circularly polarized light can be obtained in a wide wavelength range such as a visible light region. A range of transmitted circularly polarized light can be obtained.

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 optical film in which the optical layer is laminated on the polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. In addition, there is an advantage that the manufacturing process of a liquid crystal display device can be improved by being excellent in stability of quality and assembling work. Appropriate adhesion means such as an adhesive layer may be used for lamination. When adhering the above polarizing plate and other optical layers,
These optical axes can be arranged at appropriate angles according to the intended phase difference characteristics and the like.

The adhesive strength when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive type optical film and the polycarbonate type stretched film are stuck together is 20
The width is preferably N / 25 mm or more, and the stronger the adhesive force at this time, the more preferable.

The method for measuring the adhesive strength is not particularly limited, but for example, two pressure-sensitive adhesive type polarizing plate samples in which the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive composition is provided on the polarizing plate are used.
The sample is cut into a width of 5 mm and attached to a polycarbonate-based stretched film. Next, this sample is autoclaved at 50 ° C. and 0.5 MPa for 15 minutes. Using a tensile tester, this was tested under a room temperature atmosphere (25 ° C.) at a peeling rate of 300 mm / min for 9 minutes.
The adhesive force can be measured by determining the force required for 0 ° peeling.

The adhesive optical film of the present invention can be preferably used for forming an image display device such as a liquid crystal display device, an organic EL display device and a PDP.

The liquid crystal display device can be formed in a conventional manner. That is, a liquid crystal display device is generally formed by incorporating a drive circuit by appropriately aligning components such as a liquid crystal cell, an adhesive optical film, and an illumination system as necessary, but in the present invention, There is no particular limitation except that the polarizing plate or the optical film according to the present invention is used, and the conventional method can be applied. 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 an adhesive optical film is arranged on one side or both sides of a liquid crystal cell, or a device using a backlight or a reflector in an illumination system. In that case, the polarizing plate or the optical film according to the present invention can be installed on one side or both sides of the liquid crystal cell. When a polarizing plate or an optical film is provided on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, for example, a diffusion plate, an anti-glare layer,
One or two or more layers of appropriate components such as an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, and a backlight can be arranged at appropriate positions.

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 on the principle of exciting a substance and emitting light when the excited fluorescent substance returns 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 non-linearity due to the rectification property with respect to the applied voltage.

In the organic EL display device, at least one of the electrodes must be transparent in order to take out light emitted from the organic light emitting layer. Usually, indium tin oxide (IT) is 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 use the electron injection as a stomach 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 may be provided on the surface side of the electrode, and a retardation film may be provided between the transparent electrode and the polarizing plate.

Since the retardation film 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. In particular, if the retardation film is composed of a quarter-wave plate and the angle formed by the polarization directions of the polarizing plate and the retardation film is adjusted to π / 4, the mirror surface of the metal electrode can be completely shielded. .

That is, as for 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 light due to the retardation film. Especially, the retardation film is a quarter wavelength plate, and the angle formed by the polarization directions of the polarizing plate and the retardation film is π /
When it is 4, circularly polarized light is obtained.

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 again by the retardation film. . 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.

[0074]

EXAMPLES Next, examples of the present invention will be described to more specifically describe. However, the scope of the present invention is not limited by the following examples. In the following, "parts" means "parts by weight".

Example 1 In a four-necked separable flask equipped with a stirrer, a thermometer and a water separation tube, a polycarbonate diol [“PLACCEL CD220P manufactured by Daicel Chemical Industries, Ltd.]
L ", hydroxyl value: 56.1 KOHmg / g] 250 g,
20.5 g of adipic acid and 69 mg of titanium tetraisopropoxide (hereinafter referred to as TPT) as a catalyst were charged, and in the presence of a small amount of toluene as a solvent for discharging reaction water, the temperature was raised to 180 ° C. with stirring. Hold at temperature. After a while, water outflow separation is observed and the reaction begins to proceed. The reaction continued for about 22 hours,
A polyester having a weight average molecular weight of 65,000 was obtained.

After diluting this polyester with toluene to a solid content concentration of 40% by weight, a trimethylolpropane / hexamethylene diisocyanate trimer adduct [Nippon Polyurethane Co., Ltd.] per 100 parts (solid content) of the polyester is used as a crosslinking agent. Manufactured, Coronate HL] was added to give an adhesive composition. This adhesive composition was applied onto a polyethylene terephthalate release film having a thickness of 38 μm (hereinafter referred to as PET release film) with an applicator and dried at 120 ° C. for 3 minutes to give a thickness of 2
A 5 μm pressure-sensitive adhesive layer was formed. This pressure-sensitive adhesive layer was transferred to a polarizing plate [SEG1425Du manufactured by Nitto Denko Corporation] to prepare a pressure-sensitive adhesive type polarizing plate sample.

Example 2 In a four-neck separable flask equipped with a stirrer, a thermometer and a water separation tube, a polycarbonate diol [“PLACCEL CD220P manufactured by Daicel Chemical Industries, Ltd.]
L ", hydroxyl value: 56.1 KOHmg / g] 250 g,
55.2 g of sebacic acid and 95 mg of TPT were charged, and an adhesive polarizing plate sample was prepared in the same manner as in Example 1.

Comparative Example 1 100 parts of butyl acrylate, 5 parts of acrylic acid, 150 parts of ethyl acetate were placed in a reaction vessel equipped with a stirrer and a thermometer.
0.5 parts of azobisisobutyronitrile was added, and solution polymerization was carried out at 60 ° C. for about 7 hours in a nitrogen gas atmosphere to obtain a solid content of 40
% Acrylic acid copolymer was obtained. To 100 parts of this acrylic acid copolymer, 0.6 part of tolylene diisocyanate [Coronate L, manufactured by Nippon Polyurethane Co., Ltd.] was added to obtain a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition was applied onto a PET release film having a thickness of 38 μm with an applicator and dried at 130 ° C. for 3 minutes to give a thickness of 25 μm.
m adhesive layer was formed. This pressure-sensitive adhesive layer was transferred to a polarizing plate [SEG1425Du manufactured by Nitto Denko Corporation] to prepare a pressure-sensitive adhesive type polarizing plate sample.

<Measurement of Adhesive Strength> A pressure-sensitive adhesive type polarizing plate sample is cut into a width of 25 mm, attached to a polycarbonate film, and autoclaved at 50 ° C. and 0.5 MPa for 15 minutes. The adhesive strength of this was measured at 90 ° peeling under a room temperature atmosphere (25 ° C.) under a peeling speed of 300 mm / min.

<Measurement of Solvent-insoluble Component in Adhesive Layer> The adhesive was scraped off from the sample, and about 0.1 g was precisely weighed. This was immersed in toluene for 5 days, the solvent-insoluble matter was taken out, dried at 130 ° C. for 2 hours, the weight thereof was determined, and the ratio (% by weight) to the weight before immersion was calculated.

[0081]

[Table 1]

As is clear from the results shown in Table 1 above, in Examples 1 and 2 in which the pressure-sensitive adhesive composition using a polymer having a polycarbonate structure as a base polymer was used, the solvent-insoluble component was 60% or more, and the polycarbonate was used. It can be seen that the adhesive strength with respect to is over 20 N / 25 mm width, indicating a sufficient adhesive strength. On the other hand, in Comparative Example 1 in which the acrylic pressure-sensitive adhesive was used, the adhesive force to the polycarbonate was 20 N / 25 mm width or less, and sufficient adhesive force was obtained, even though the solvent-insoluble component was 60% or more. I know there isn't.

[0083]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, in a pressure-sensitive adhesive type optical film composed of a pressure-sensitive adhesive layer and an optical film, which is used in an image display device such as a liquid crystal display device, the pressure-sensitive adhesive layer has a polycarbonate structure. By using the pressure-sensitive adhesive composition containing the polymer as a base polymer, a pressure-sensitive adhesive optical film having a high adhesive force of 20 N / 25 mm width or more to a polycarbonate film is provided.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H049 BA02 BA04 BA06 BA25 BB27                       BB43 BB51 BB63 BC03 BC14                       BC22                 2H091 FA08X FA11X FD15 FD16                       GA17 LA01                 4J004 AB01 CA06 CB03 CC02 FA01                       FA04                 4J040 EL021 JA09 JB09 LA06                       MA10 NA17 PA23

Claims (6)

[Claims] 1. A pressure-sensitive adhesive type optical film having a pressure-sensitive adhesive layer provided on one side or both sides of an optical film, wherein the pressure-sensitive adhesive composition forming the pressure-sensitive adhesive layer contains a polymer having a polycarbonate structure as a base polymer. Characteristic adhesive optical film. 2. An adhesive optical film in which an adhesive layer is provided on one side or both sides of an optical film, the adhesive force (peeling angle 90 ° when the film is attached to a stretched polycarbonate film using the adhesive layer. , Peeling speed 300mm
/ Min) is an adhesive optical film using an adhesive composition having a width of 20 N / 25 mm or more. 3. An adhesive optical film having an adhesive layer provided on one side or both sides of an optical film, wherein the adhesive composition forming the adhesive layer contains a polymer having a polycarbonate structure as a base polymer, Adhesive strength (peeling angle 90 °, peeling speed 300 mm / min) when it is adhered to polycarbonate using adhesive layer is 20 N /
An adhesive optical film having a width of 25 mm or more. 4. A pressure-sensitive adhesive optical film, wherein the solvent-insoluble component in the pressure-sensitive adhesive composition according to claim 1 is 60% by weight or more. 5. An adhesive optical film, wherein the optical film constituting the adhesive optical film according to any one of claims 1 to 4 is a polycarbonate-based stretched film. 6. An image display device using the pressure-sensitive adhesive optical film according to claim 1.