JP2003344658A - Optical film, laminated polarizing plate, and image display device using the same - Google Patents

Abstract

(57) Abstract: An optical film having uniform, transparent, negative birefringence, and extremely excellent optical properties, a laminated polarizing plate obtained by laminating the same, and a liquid crystal display device using them. Provided is a self-luminous display device. An optical film obtained by coating at least one polymer selected from the group consisting of polyetherketone, polyaryletherketone, and polyetheretherketone on a substrate, wherein the optical film has the following properties: The optical film satisfies all of the expressions (1) to (3) and has a birefringence in the range of 0.0005 to 0.1. nx>ny> nz (1) 3 nm ≦ (nx−ny) · d (2) (nx−nz) / (nx−ny)> 1 (3) (in equations (1) to (3), nx and ny) Is the main refractive index in the film plane, nz is the refractive index in the film thickness direction, d
Is the film thickness. ).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical film, an optical compensation layer-integrated laminated polarizing plate in which the optical film is laminated, a liquid crystal display device using the same, and a self-luminous display device.

[0002]

2. Description of the Related Art Conventionally, biaxial retardation plates for optical compensation of various liquid crystal display devices have been produced by using a polymer film stretching technique. For example, there are a roll-to-roll tensile stretching method, a roll-to-roll compression stretching method, a tenter transverse uniaxial stretching method, and the like (JP-A-3-33719). Depending on the case, there is also a method of obtaining a retardation plate by biaxially stretching under a condition having anisotropy due to the strength of the film (Japanese Patent Laid-Open No. 3-24502). Further, a uniaxially stretched polymer film having a positive optical anisotropy and a biaxially stretched polymer film having a negative optical anisotropy with a small in-plane retardation value are used together and arranged as an optical compensation plate. A liquid crystal display device characterized by being provided is also disclosed (Japanese Patent Laid-Open No. 4-194820). In addition to this, there is also a method of forming a negative birefringent film by forming a film of polyimide (Japanese Patent Laid-Open No. 8-511).
812 publication).

Using the stretching technique as described above, nx
A retardation film having a characteristic of ≧ ny> nz is produced, and the retardation film is arranged between a driving cell and a polarizer to form a liquid crystal display device in which the liquid crystal cell has a viewing angle compensation.

[0004]

However, the above-mentioned stretching technique requires a precise stretching operation,
Detailed setting of the drawing conditions such as the draw ratio and axis and precise control are required. It is also necessary to solve the Boeing phenomenon. For further stretching, the film cannot be stretched unless the film has a certain thickness, which causes a problem that the stretched retardation film or the liquid crystal display device becomes thicker. Further, in the above-mentioned Japanese Patent Publication No. 8-511812, a uniaxial retardation plate using polyimide is disclosed. In this case, negative birefringence having a characteristic of 0 nm≈ (nx−ny) · d. There is a problem that only a retardation film having a negative polarity can be produced.

The present invention has been made in view of the above-mentioned conventional problems, and is an optical film having uniform, transparent, negative birefringence, and extremely excellent optical properties, and a laminated film formed by laminating the optical films. An object of the present invention is to provide a polarizing plate, a liquid crystal display device using the same, and a self-luminous display device.

[0006]

In order to achieve the above object, the present invention provides at least one polymer selected from the group consisting of polyetherketone, polyaryletherketone and polyetheretherketone on a substrate. Provided is an optical film which is obtained by coating, wherein the optical film satisfies all of the following formulas (1) to (3) and has a birefringence of 0.0005 to 0.1. To do. nx>ny> nz (1) 3 nm ≦ (nx-ny) · d (2) (nx-nz) / (nx-ny)> 1 (3) (where nx, ny in formulas (1) to (3)) Is the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, d
Is the film thickness. )

By using the above method for producing the optical film of the present invention, as shown in FIG. 4, it extends in the direction perpendicular to the axis of the thickness direction of the film and is included in the thickness of this film. The axis extending in the direction showing the maximum value among the refractive indexes along the plurality of axes is defined as the main axis, and the refractive index in the main axis direction is nx, and the direction along the axis perpendicular to both the main axis and the axis in the thickness direction. Where ny is the index of refraction, nz is the index of refraction along the axis of the thickness direction, and d is the thickness, the characteristic represented by Formula (1); nx>ny> nz, Relationship of (2); 3 nm ≦ (nx−ny) · d, and relationship of Formula (3); (nx−nz) / (nx−ny)> 1
It is possible to easily obtain a biaxial retardation plate satisfying all the above conditions. The biaxial retardation plate is formed by satisfying the relationships of the above expressions (2) and (3).

Further, in the optical film of the present invention,
It is preferable to have an adhesive layer or an adhesive layer on one side or both sides. This facilitates adhesion to other optical layers and other members such as liquid crystal cells, and can prevent peeling of the retardation plate.

Further, the present invention provides a laminated polarizing plate comprising at least one layer of the above optical film and a polarizer or a polarizing plate laminated thereon.

Furthermore, the present invention provides a liquid crystal display device characterized in that the optical film or the laminated polarizing plate is arranged on at least one side of a liquid crystal cell. By disposing this optical film between the liquid crystal cell and the polarizing plate, it is possible to make the liquid crystal display device thinner.

The present invention also provides a self-luminous display device using the optical film or the laminated polarizing plate.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The optical film of the present invention is an optical film obtained by coating a substrate with at least one polymer selected from the group consisting of polyetherketone, polyaryletherketone and polyetheretherketone. A film, wherein the optical film satisfies all of the following formulas (1) to (3) and has a birefringence of 0.0005 to 0.005:
It is in the range of 0.1. nx>ny> nz (1) 3 nm ≦ (nx-ny) · d (2) (nx-nz) / (nx-ny)> 1 (3) (where nx, ny in formulas (1) to (3)) Is the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, d
Is the film thickness. )

In the present invention, the birefringence (Δn)
Is defined by the following equation.

[Formula 1] Δn = (nx−nz) · d / thickness

The value of the birefringence (Δn) of the optical film is
When it is less than 0.0005, it becomes a thick type retardation plate, and it becomes 0.
If it exceeds 1, it becomes a thin retardation plate and it becomes difficult to control the retardation. Therefore, in order to obtain a thin biaxial retardation plate excellent in productivity, the value of Δn is preferably 0.001 to 0.001. 0.
It is in the range of 08, particularly preferably 0.005-0.0
It is preferably in the range of 5.

The thickness of the optical film is not particularly limited, but it is preferably 0.5 to 30 μm, and more preferably from the viewpoint of providing a film that is excellent in the viewing angle compensation function and uniform while making the liquid crystal display device thinner. Is 1 to 20 μm
It should be

When forming the optical film of the present invention, at least one polymer selected from the group consisting of polyetherketone, polyaryletherketone and polyetheretherketone is used as a material. These polymers are suitable as a material for the biaxial retardation plate because they have excellent heat resistance and chemical resistance, are highly rigid, and have excellent transparency.

The above-mentioned polyetherketone, polyaryletherketone and polyetheretherketone are not particularly limited, and conventionally known polymer materials can be appropriately used as long as they can satisfy the optical film characteristics of the present invention. It can be used alone or in any combination.
The molecular weight of these polymers is not particularly limited, but the weight average molecular weight (Mw) is 10,000 to 1,000,
The range of 000 is preferable, and 20,000 is more preferable.
It is preferably in the range of 0 to 800,000.

Among the above-mentioned polymer materials, polyaryl ether ketone is transparent and has a high glass transition temperature, so that an optical film having high heat resistance can be obtained. The polyaryl ether ketone referred to in the present invention means an ether group (—O—) and a ketone group (C
(= O)) and they are linked by an aryl group, and the general formula thereof is represented by the following formula (Formula 1).

[0019]

[Chemical 1] (In the formula, F is a fluorine atom, A ′ is a halogen atom,
A lower alkyl group or a lower alkoxy group, x and y are integers from 0 to 4, and m is 0 or 1. Also,
n represents the degree of polymerization, and R ¹ is a group represented by the general formula (Formula 2). )

[0020]

[Chemical 2] (In the formula, z and x ′ are integers of 0 to 4, s is 0 or 1, and R ² is a divalent aromatic group. A ′ and F
Is the same as (Chemical Formula 1). )

Among them, in the general formula (Formula 1), y = 0 is preferable, and y = 0 and x ′ = 0 is more preferable.

In the above general formula (Formula 2), 2
The valent aromatic group (R ² ) is preferably any of the following 6 kinds.

[Chemical 3]

Specific examples of such preferable polyaryl ether ketones include those represented by the following structural formula (Formula 4) or (Formula 5).

[0024]

[Chemical 4]

[0025]

[Chemical 5]

The optical film may be composed of the above polyaryl ether ketone alone, or may be composed of another resin such as polyether sulfone, polyether, polyimide, polyamide, etc. within the range in which the characteristics of the polyaryl ether ketone are not lost. It may be composed of a blended product of one or more resins selected from polyesters, polyamideimides, polyesterimides, polycarbodiimides, and polyetherketones having different compositions, or a polyaryl ether composed of two or more repeating units. It may be a ketone copolymer.

In the case of producing the optical film of the present invention, for example, a polymer material such as polyetherketone, polyaryletherketone and polyetheretherketone is coated on a substrate having shrinkability in one direction and dried. By doing so, it is possible to make the coated polymer material have an in-plane refractive index difference by utilizing the in-plane shrinkage difference of the substrate. Further, a method of thinning the base material on which stress is applied in one direction, or a method of blowing air from one direction to thin the base material may be used. Alternatively, various methods such as a method of coating a polymer material on a substrate having anisotropy can be applied.

In the above, the polymer may be applied by a heating and melting method, or a polymer solution obtained by dissolving it in a solvent may be applied. From the viewpoint of production efficiency and optical anisotropy control, a method of applying a polymer solution is preferable, and a solution of a polyaryl ether ketone dissolved in a solvent is applied to a substrate, and the coating film can be produced by drying. it can.

The solvent for dissolving the polyaryl ether ketone is not particularly limited as long as it can dissolve the polyaryl ether ketone. For example, halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, trichloroethylene, tetrachloroethylene, chlorobenzene, orthodichlorobenzene; phenols such as phenol and parachlorophenol; benzene, toluene, xylene, methoxybenzene, Aromatic hydrocarbons such as 1,2-dimethoxybenzene; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone, N-methyl-2-pyrrolidone; ethyl acetate, butyl acetate Ester solvents such as; t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol,
Alcohol solvents such as ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol and 2-methyl-2,4-pentanediol; amide solvents such as dimethylformamide and dimethylacetamide; nitrile solvents such as acetonitrile and butyronitrile. It is possible to use ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran; or carbon disulfide, ethyl cellosolve, butyl cellosolve, etc., alone or in combination. When applied as a polymer solution, from the viewpoint of viscosity, the above polymer is 5 to 50 parts by weight, preferably 10 to 100 parts by weight of the solvent.
It is preferable to use 40 parts by weight as a mixture.

The coating treatment may be carried out by an appropriate method such as a spin coating method, a roll coating method, a flow coating method, a printing method, a dip coating method, a casting film forming method, a bar coating method or a gravure printing method. it can. At the time of coating, a superposition method of polymer layers and the like can be adopted if necessary.

After coating, air drying or 60 to 25
By heating at 0 ° C., the polymer is immobilized on the base material to form a polymer layer on the base material. The obtained optical film may be used in the form of a laminate as an integrated body with a supporting base material, or may be used as an optical film by peeling the polymer layer from the base material. When forming the polymer layer, various additives such as stabilizers, plasticizers and metals can be blended as necessary.

As the base material, an appropriate material can be used, but a film made of a polymer having excellent transparency is preferable. Examples of the polymer, acetate resin such as triacetyl cellulose, polyester resin, polyether sulfone resin, polysulfone resin, polycarbonate resin, polyamide resin,
Polyimide resin, polyolefin resin, acrylic resin, polynorbornene resin, cellulose resin, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyacrylic resin Examples thereof include resins and liquid crystal polymer systems.

The above-mentioned substrate may be a monolayer or a multilayer such as a film laminated with different polymers for various purposes such as improvement of strength, heat resistance and adhesion of polymer. May be. Further, it may be one that does not cause a phase difference due to birefringence, or one that causes a phase difference due to birefringence.

The transparent substrate that produces a phase difference due to birefringence is
For example, it can be obtained as a stretched film or the like, and may have a controlled refractive index in the thickness direction. The control can be performed by, for example, a method of heating and stretching the polymer film while adhering it to the heat-shrinkable film.

The thickness of the base material can be appropriately determined according to the purpose of use and the like, but from the viewpoint of strength and thinning, it is preferably 5 to 500 μm, more preferably 10 to 200 μm. Particularly preferably 15 to 150 μm
It should be in the range of. The polymer layer may be provided in one layer or two or more layers on one side or both sides of the transparent substrate.

Next, a laminated polarizing plate obtained by laminating at least one optical film (birefringent film) of the present invention and a polarizing plate will be described.

The polarizing plate used in the present invention is not particularly limited, but its basic constitution is such that a suitable adhesive layer is formed on one side or both sides of a polarizer made of a polyvinyl alcohol-based polarizing film containing a dichroic substance, For example, a transparent protective film serving as a protective layer is adhered via an adhesive layer made of vinyl alcohol polymer or the like.

As the polarizer (polarizing film), for example, a film made of a vinyl alcohol polymer such as polyvinyl alcohol or partially formalized polyvinyl alcohol is dyed with a dichroic substance such as iodine or a dichroic dye, and stretched. Appropriate treatments such as treatments and cross-linking treatments performed in an appropriate order or method and capable of transmitting linearly polarized light when natural light is incident can be used. A polarizing film formed of a polyene oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride may be used. Among them, a polyvinyl alcohol-based film in which iodine or a dichroic dye is adsorbed and oriented is preferable. In particular, those having excellent light transmittance and polarization degree are preferable. The thickness of the polarizing film is generally 1 to 80 μm, but is not limited to this.

An appropriate transparent film can be used as a protective film material which is a transparent protective layer provided on one side or both sides of the polarizer (polarizing film). Above all, a film made of a polymer having excellent transparency, mechanical strength, thermal stability, moisture shielding property and the like is preferably used. Examples of the polymer include acetate resins such as triacetyl cellulose, polyester resins, polyether sulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polynorbornene resins, polyolefin resins, polyacrylic resins. Examples thereof include resins, but are not limited thereto. A transparent protective film that can be particularly preferably used in terms of polarization characteristics and durability is a triacetyl cellulose film whose surface is saponified with an alkali or the like. The thickness of the transparent protective film is arbitrary, but generally 500 μm or less, preferably 5 to 300 μm for the purpose of thinning the polarizing plate.
m, particularly preferably 5 to 150 μm. When the transparent protective films are provided on both sides of the polarizing film, the transparent protective films made of different polymers may be used on the front and back.

The transparent protective film used for the protective layer is
As long as the object of the present invention is not impaired, a hard coat treatment, an antireflection treatment, a treatment for the purpose of preventing sticking, diffusion or antiglare, or the like may be applied. The hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate.
It is possible to form a cured skin film, which is made of a suitable ultraviolet-curable resin such as urethane-based, acrylic-based, or epoxy-based resin, and has excellent hardness and slipperiness, by a method of adding it to the surface of the transparent protective film.

On the other hand, the antireflection treatment is carried out for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the prior art. In addition, anti-sticking is performed for the purpose of preventing adhesion with an adjacent layer, and anti-glare treatment is performed for the purpose of preventing external light from being reflected on the surface of the polarizing plate and hindering visual recognition of light transmitted through the polarizing plate. 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 such as a sandblasting method or an embossing method or a method of blending transparent fine particles.

Examples of the transparent fine particles include silica and alumina having an average particle size of 0.5 to 20 μm, titania and zirconia, tin oxide and indium oxide, cadmium oxide and antimony oxide. Fine particles may be used, or organic fine particles made of crosslinked or non-crosslinked polymer particles may be used.
The amount of transparent fine particles used is 2 per 100 parts by weight of transparent resin.
It is generally 70 to 70 parts by weight, especially 5 to 50 parts by weight.

The antiglare layer containing transparent fine particles can be provided as the transparent protective film itself or as a coating layer on the surface of the transparent protective film. The anti-glare layer may also serve as a diffusion layer (viewing angle compensation function or the like) for diffusing light transmitted through the polarizing plate and expanding the viewing angle. The antireflection layer, the sticking prevention layer, the diffusion layer, the antiglare layer, and the like may be provided as an optical layer formed of a sheet provided with these layers, separately from the transparent protective film.

The adhesion treatment between the polarizer and the transparent protective film as the protective layer is not particularly limited, but for example, an adhesive made of an acrylic polymer or a vinyl alcohol polymer, or boric acid or borax. Alternatively, it can be carried out via an adhesive or the like made of at least a water-soluble crosslinking agent of a vinyl alcohol polymer such as glutaraldehyde, melamine, and oxalic acid. This makes it difficult to peel off due to the influence of humidity and heat, and makes it possible to provide excellent light transmittance and polarization degree. Such an adhesive layer is formed as a coating dry layer of an aqueous solution or the like, but other additives and a catalyst such as an acid can be added as necessary when preparing the aqueous solution. In particular, it is preferable to use an adhesive made of polyvinyl alcohol because of its excellent adhesion to the PVA film.

When a polarizing plate and an optical film are laminated to form a laminated polarizing plate, the both can be laminated using an appropriate adhesive means such as an adhesive layer or an adhesive layer, but the present invention is not limited to this. is not. For example, it is possible to use a polymer film such as triacetyl cellulose used as a protective layer of a polarizing plate as a substrate and form the polymer layer on the substrate. Then, a polymer film such as triacetyl cellulose may be adhered to the polarizer, and only the polymer film such as triacetyl cellulose may be adhered to the other side of the polarizer. When laminating by such a method, the optical film supporting substrate can be used as a protective film on one side of the polarizing plate.

FIG. 1 is a view showing the constitution of a polarizing plate integrated with an optical compensation layer, which is obtained by laminating an optical film (birefringent film) of the present invention and a polarizer. As shown in FIG. 1, the birefringent film (1) can be put to practical use as an optical compensation integrated type polarizing plate in a state where the polarizer (2) is adhered via an adhesive layer, if necessary. In the case of the illustrated example, the protective film (3) is adhered to the outside of the polarizer (2).

As shown in FIG. 2, the polarizing plate (11) can be put into practical use as a polarizing plate integrated with optical compensation, with the polarizing plate (11) adhered via an adhesive layer, if necessary. In the case of the polarizing plate shown in the figure, protective films (3) are adhered to both sides of the polarizer (2). By integrating with such a polarizer or a polarizing plate, the workability of handling can be further improved, and the assembly process of the liquid crystal display device or the like can be simplified.

The adhesive (adhesive) used for lamination is not particularly limited, and for example, transparent pressure sensitive adhesive such as acrylic, silicone, polyester, polyurethane, polyether, rubber, etc. An appropriate adhesive can be used. From the viewpoint of preventing changes in optical properties of optical films and the like, those that do not require a high temperature process at the time of curing or drying are preferable, and those that do not require a long curing treatment or drying time are desirable. Further, those which do not cause peeling under heating or humidifying conditions are preferably used.

The optical film of the present invention comprises various retardation plates,
It can also be used in combination with a diffusion control film, a brightness enhancement film or the like. Examples of the retardation plate include a uniaxially stretched polymer, a biaxially stretched polymer, a Z-axis oriented treatment product, and a liquid crystal polymer-coated product. Diffusion control film, diffusion, scattering, to control the viewing angle,
Film using refraction, glare related to resolution,
A film that uses diffusion, scattering, or refraction to control scattered light or the like can be used. As the brightness enhancement film, a brightness enhancement film using selective reflection of a cholesteric liquid crystal and a λ / 4 plate, a scattering film using anisotropic scattering depending on the polarization direction, and the like can be used. Further, it may be used in combination with a wire grid type polarizer.

The optical film and the laminated polarizing plate according to the present invention can be preferably used for forming various liquid crystal display devices, etc., but in the application thereof, a polarizing plate or a reflective layer may be provided through an adhesive layer or a pressure-sensitive adhesive layer if necessary. One or more layers of other optical layers such as a plate, a semi-transmissive reflector, and a brightness enhancement film can be laminated. In particular, the laminated polarizing plate in which the polarizing plate and the optical film of the present invention are laminated is used as a polarizing plate having an optical compensation function.

The above-mentioned reflection plate is provided on a polarizing plate to form a reflection type polarizing plate. The reflective polarizing plate is usually placed on the back side of the liquid crystal cell and is on the viewing side (display side).
A liquid crystal display device (reflection-type liquid crystal display device) of a type that reflects and displays incident light from the device is formed. The reflective polarizing plate has an advantage that a light source such as a backlight can be omitted and the liquid crystal display device can be easily thinned. 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. Specific examples thereof include a transparent protective film that is mat-treated if necessary, and a reflective layer formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum to one surface of the transparent protective film.

Further, there may be mentioned a reflection type polarizing plate having a reflective layer reflecting the fine concavo-convex structure on the transparent protective film containing fine particles and having a fine concavo-convex structure on the surface. The reflective layer having a fine surface irregularity structure has an advantage of diffusing incident light by diffuse reflection, preventing directivity and glare, and suppressing uneven brightness. The transparent protective film can be formed by a method of directly attaching a metal to the surface of the transparent protective film 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. .

Further, the reflection plate may be used as a reflection sheet or the like in which a reflection layer is provided on an appropriate film conforming to the transparent protective film instead of directly attaching to the transparent protective film of the polarizing plate. it can. Since the reflective layer of the reflective plate is usually made of metal, the use form in which the reflective surface is covered with a film or a polarizing plate is to prevent reduction of the reflectance due to oxidation, and thus to maintain the initial reflectance for a long time. Also, it is preferable from the viewpoint of avoiding the additional provision of the protective layer.

The semi-transmissive polarizing plate is a semi-transmissive reflective layer in the above reflective polarizing plate, and examples thereof include a half mirror that reflects and transmits light at the reflective layer.
The semi-transmissive polarizing plate is usually provided on the back side of the liquid crystal cell, and when a liquid crystal display device is used in a relatively bright atmosphere, it reflects incident light from the viewing side (display side) to display an image. In a relatively dark atmosphere, a liquid crystal display device of the type that displays an image using a built-in light source such as a backlight built in the back side of a semi-transmissive polarizing plate is formed. 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.

Further, as the above-mentioned brightness enhancement film,
For example, a dielectric multi-layered thin film or a multi-layered laminate of thin films having different refractive index anisotropies, which shows the property of transmitting linearly polarized light of a predetermined polarization axis and reflecting other light (“D” manufactured by 3M). -BEF ", etc.), a cholesteric liquid crystal layer, especially an oriented film of a cholesteric liquid crystal polymer, or one having an oriented liquid crystal layer supported on a film substrate (Nitto Denko Corporation" P
CF350 ", Merck" Transmax ")
As described above, an appropriate one can be used, such as one having a characteristic of reflecting either left-handed or right-handed circularly polarized light and transmitting other light.

The above-mentioned optical member in which two or more optical layers are laminated can be formed by a method of sequentially laminating in the manufacturing process of a liquid crystal display device or the like. The optical member is excellent in quality stability and assembling workability, and has an advantage that the manufacturing efficiency of the liquid crystal display device can be improved. In addition, for stacking,
Appropriate adhesive means such as an adhesive layer or an adhesive layer can be used.

Optical film of the present invention (biaxial retardation plate)
An adhesive layer or an adhesive layer for adhering to other optical layers or other members such as liquid crystal cells may be provided on the laminated polarizing plate or the like. The adhesive (adhesive) layer can be appropriately formed by using a conventionally known adhesive such as acrylic. Among them, prevention of foaming phenomenon or peeling phenomenon due to moisture absorption, prevention of warpage of liquid crystal cell due to deterioration of optical characteristics due to thermal expansion difference, etc., and therefore, high moisture absorption rate in terms of formability of a liquid crystal display device having high quality, The adhesive layer is preferably low and has excellent heat resistance. Further, an adhesive layer or the like which contains fine particles and exhibits a light diffusing property can be used. The adhesive (adhesion) layer may be provided on a necessary surface as necessary.

When the adhesive (adhesive) adhesive layer provided on an optical film (biaxial retardation plate), a laminated polarizing plate or the like is exposed on the surface, the adhesive (adhesive) adhesive layer is put into practical use until it is put to practical use. It is preferable to temporarily cover with a separator for the purpose of preventing contamination. The separator is formed by, for example, a method in which an appropriate thin sheet conforming to the above-mentioned transparent protective film or the like is provided with a release coat with an appropriate release agent such as a silicone-based or long-chain alkyl-based, fluorine-based or molybdenum sulfide as necessary. be able to.

Each layer such as a polarizer, a transparent protective film and a viscous (adhesive) adhesive layer constituting the above-mentioned optical film or laminated polarizing plate is, for example, a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound or a cyano compound. It may be one having an ultraviolet absorbing ability by an appropriate method such as a method of treating with an ultraviolet absorber such as an acrylate compound or a nickel complex salt compound.

The optical film and the laminated polarizing plate of the present invention can be preferably used for forming various devices such as a liquid crystal display device. For example, a reflective type film having polarizing plates arranged on one side or both sides of a liquid crystal cell, It can be used for a semi-transmissive type or a transmissive / reflective type liquid crystal display device. The liquid crystal cell forming the liquid crystal display device is arbitrary, and an appropriate type such as an active matrix drive type represented by a thin film transistor type, a simple matrix drive type represented by a twist nematic type or a super twist nematic type, etc. The liquid crystal cell may be used.

The optical film of the present invention is VA (Ve
Since it is very excellent in optical compensation of a vertical aligned cell, it can be most suitably used as a viewing angle compensation film for a VA mode liquid crystal display device.

FIG. 3 is a view showing the constitution of a liquid crystal display device in which the optical film (birefringent film) of the present invention is arranged between the liquid crystal cell (21) and the polarizer (2). As shown in FIG. 3, a liquid crystal cell (21) may be bonded to the side having the birefringent film (1) through an adhesive layer (not shown) to provide a practical form.

When polarizing plates and optical members are provided on both sides of the liquid crystal cell, they may be the same or different. Further, when forming the liquid crystal display device, one or two or more layers can be arranged at appropriate positions with appropriate components such as a prism array sheet, a lens array sheet, a light diffusion plate and a backlight.

Further, the optical film (birefringent film) and laminated polarizing plate of the present invention are used for organic EL display, PD
A self-luminous display device such as a P or FED can be used in the same manner as a liquid crystal display device. When it is provided in a self-luminous flat display, by setting Δnd = λ / 4, circularly polarized light can be obtained and it can be used as an antireflection filter.

[0065]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples. The characteristics of the optical film were evaluated by the following methods.

(Measurement of Phase Difference and Alignment Axis Accuracy) A phase difference meter (KOBRA21ADH manufactured by Oji Scientific Instruments) was used for measurement.

(Refractive index measurement) KOBR manufactured by Oji Scientific Instruments
The refractive index at 590 nm was measured using A21ADH.

(Measurement of film thickness) The film thickness was measured using a digital micrometer K-351C manufactured by Anritsu.

Example 1 A solution prepared by using methyl isobutyl ketone as a solvent in a polyaryl ether ketone A (manufactured by Nippon Shokubai Co., Ltd.) having a structural formula represented by the above structural formula (Formula 4) to prepare a solution of 15% by weight was prepared. It was applied onto triacetyl cellulose having a thickness of 75 μm which was laterally stretched 1.3 times by fixed-end lateral stretching at 150 ° C. Then at 100 ℃ for 10 min
Heat treatment was performed to obtain a completely transparent and smooth film having a thickness of 10 μm. When the characteristics of this film were evaluated, nx
It was a retardation plate having a birefringent layer of>ny> nz.

Example 2 The same solution as in Example 1 was used and applied onto polyethylene terephthalate having a thickness of 75 μm which was laterally stretched 1.3 times by fixed-end lateral stretching at 150 ° C. Then, heat treatment was performed at 150 ° C. for 5 minutes to obtain a completely transparent film having a thickness of 6 μm after peeling. This film was a retardation plate having a birefringent layer of nx>ny> nz.

Example 3 The same solution as in Example 1 was used, and this solution was coated on triacetyl cellulose. Thereafter, heat treatment was performed at 100 ° C. for 10 minutes to obtain a completely transparent and smooth film having a thickness of 10 μm. After that, the film formed on the triacetyl cellulose is 150 ° C. for each substrate.
The film was longitudinally uniaxially stretched at 10%. The resulting film is
The retardation plate had a birefringent layer of nx>ny> nz.

Example 4 A solution prepared by using cyclohexanone as a solvent in polyaryletherketone B (manufactured by Nippon Shokubai Co., Ltd.) represented by the above structural formula (Formula 5) to prepare a 15 wt% solution was fixed at 150 ° C. It was applied onto triacetyl cellulose having a thickness of 75 μm which was laterally stretched 1.3 times by lateral stretching. After that, heat treatment at 100 ° C for 10 minutes,
A completely transparent and smooth film having a thickness of 3 μm was obtained. When the characteristics of this film were evaluated, it was a retardation plate having a birefringent layer of nx>ny> nz.

Example 5 A solution prepared by mixing 15% by weight of 8F-PEKEK-6FBA (Mw: 500,000) represented by the above structural formula (Chemical Formula 4) with methyl isobutyl ketone as a solvent was fixed at 150 ° C. It was applied onto triacetyl cellulose having a thickness of 75 μm which was laterally stretched 1.3 times by lateral stretching. Thereafter, heat treatment was performed at 100 ° C. for 10 minutes to obtain a completely transparent and smooth film having a thickness of 10 μm. When the characteristics of this film were evaluated, it was a retardation plate having a birefringent layer of nx>ny> nz.

(Comparative Example 1) A polynorbornene resin film having a Δn of about 0.002 (manufactured by JSR Corporation, ARTON)
The film) was stretched 1.3 times by fixed-end transverse stretching at 175 ° C. to obtain a film having a thickness of 80 μm. When the birefringence of this film was evaluated, it was a retardation plate having a birefringence layer of nx ≧ ny> nz.

Comparative Example 2 The same solution as in Example 1 was applied onto triacetyl cellulose having a thickness of 80 μm which was not substantially stretched. Then 10 at 100 ℃
The film was heat-treated for minutes, and the film was peeled from the triacetyl cellulose to obtain a completely transparent and smooth film having a thickness of 4 μm. When the birefringence of this film was evaluated, nx
It was a retardation plate having a birefringent layer of ≈ny> nz.

Comparative Example 3 The same solution as in Example 1 was applied onto a glass plate. After that, heat treatment was performed at 100 ° C. for 10 minutes, and the film was peeled from the triacetyl cellulose to obtain a completely transparent and smooth film having a thickness of 7 μm. When this film was evaluated, it was a retardation plate having a birefringent layer of nx≈ny> nz.

Regarding the films obtained in the above Examples and Comparative Examples, the birefringence (Δn), (nx-ny) × d, (nx-n) of the films was determined from the values of nx, ny and nz.
The value of (z) × d, (nx-nz) / (nx-ny) was calculated. The results are summarized in Table 1.

[0078]

[Table 1] △ n (nx-ny) ・ d (nx-nz) ・ d (nx-nz) Thickness Orientation axis (Nm) (nm) / ( nx-ny) (μm) Accuracy Example 1 0.03 135 280 2 10 -0.5 + 0.5 Example 2 about 0.02 50 120 2 6 -0.5 + 0.5 Example 3 0.03 140 290 2 10 -0.5 to +0.5 Example 4 About 0.02 88 80 2 3 -0.5 to +0.5 Example 5 About 0.02 120 200 10 10 -0.5 to +0.5 Comparative Example 1-91 182 2 80 -2.5 to +2.5 Comparative Example 2-0.9 100 111 4- Comparative Example 3-0.3 298 993 6-

From the above results, the optical film of the present invention has nx>ny> nz and the value of (nx-ny) × d is 3.
The value of (nx-nz) / (nx-ny) is not less than 1 nm and is larger than 1, and it is understood that the film is thin and has excellent alignment axis accuracy as compared with the optical film of Comparative Example 1. In addition, Comparative Example 2
Also, in Comparative Example 3, a thin film is obtained, but a retardation plate having the characteristics of the present invention is not obtained.

Next, the biaxial retardation plate and the polarizing plate prepared in the above Example 1 (trade name “HEG14” manufactured by Nitto Denko Corporation).
25DU ”) was laminated using an acrylic pressure-sensitive adhesive to obtain a laminated polarizing plate, and the laminated polarizing plate was adhered to the liquid crystal cell so that the polarizing plate was on the outside to manufacture a liquid crystal display device. When the display characteristics were examined, it was found that the contrast and display uniformity were excellent and the display quality was good in a wide viewing angle range of the front and squint.

[0081]

As described above, according to the present invention, at least one polymer selected from the group consisting of polyetherketone, polyaryletherketone and polyetheretherketone is brought into a solution state, and only oriented in a drying process. And 3 nm ≦ (nx−ny) · d, and (nx
An optical film having a birefringence (Δn) of 0.0005 to 0.1 that satisfies the relationship of −nz) / (nx−ny)> 1 can be easily obtained. The obtained film is a thin layer, and is a biaxial retardation plate having characteristics of nx>ny> nz, uniform and transparent, and extremely excellent optical properties.

Further, by disposing the biaxial retardation plate of the present invention or the laminated polarizing plate obtained by laminating the biaxial retardation plate and the polarizing plate on at least one side of the liquid crystal cell, a wide viewing angle range of front and perspective is obtained. It is possible to realize a thin liquid crystal display device and a self-luminous display device which are excellent in display quality.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of a laminated polarizing plate (optical compensation layer-integrated polarizing plate) of the present invention.

FIG. 2 is a schematic cross-sectional view of another example of the laminated polarizing plate (optical compensation layer integrated polarizing plate) of the present invention.

FIG. 3 is a schematic sectional view showing an example of a liquid crystal display device of the present invention.

FIG. 4 is a diagram showing an axial direction of the optical film of the present invention.

[Explanation of symbols]

1 ... Birefringent film 2 Polarizer 3 Protective film 11 Polarizing plate 21 Liquid crystal cell nx, ny, nz Z direction in thickness direction , The refractive index in each axial direction when the drawing direction in the plane perpendicular to the Z axis is the X axis and the direction perpendicular to the X axis and the Z axis is the Y axis.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masatake Hayashi             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. (72) Inventor Hiroyuki Yoshimi             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 2H049 BA02 BA06 BA24 BA42 BB03                       BB51 BC22                 2H091 FA08 FA11 FB02 FC08 FC21                       FC29 FC30 FD10 FD12 FD14                       GA16 KA01 LA03 LA11 LA12                       LA18                 4F006 AA02 AB32 BA14 CA05

Claims (5)

[Claims] 1. An optical film obtained by coating a substrate with at least one polymer selected from the group consisting of polyetherketone, polyaryletherketone and polyetheretherketone, the optical film comprising: An optical film satisfying all of the following formulas (1) to (3) and having a birefringence in the range of 0.0005 to 0.1. nx>ny> nz (1) 3 nm ≦ (nx-ny) · d (2) (nx-nz) / (nx-ny)> 1 (3) (where nx, ny in formulas (1) to (3)) Is the main refractive index in the plane of the film, nz is the refractive index in the film thickness direction, d
Is the film thickness. ) 2. The optical film according to claim 1, which has an adhesive layer or an adhesive layer on one surface or both surfaces thereof. 3. A laminated polarizing plate comprising at least one layer of the optical film according to claim 1 or 2 and a polarizer or a polarizing plate. 4. A liquid crystal display device comprising the optical film according to claim 1 or 2 or the laminated polarizing plate according to claim 3 disposed on at least one side of a liquid crystal cell. 5. A self-luminous display device using the optical film according to claim 1 or 2 or the laminated polarizing plate according to claim 3.