JP2002311246A - Polarizing plate, method for manufacturing the same and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin polarizing plate which is made thin by adopting a polarizing layer formed by application of an aqueous solution containing a tablar pigment, and which has an improved polarization degree and resultant excellent contrast. SOLUTION: The polarizing plate with the thin polarizing layer 5 is manufactured by subjecting a surface of a transparent substrate 1 to rubbing treatment, subsequently applying the aqueous solution containing the tablar pigment to the rubbing treated surface, drying and forming the polarizing layer 5 with 20-1,500 nm thickness. A reflective polarizing plate is obtained by combining the polarizing plate with a reflection layer 3. As the transparent substrate 1, a cellulose type resin film, a polyester type resin film, an amorphous polyolefin type resin film (in particular a norbornene type resin film) and so on are used. The liquid crystal display device with the polarizing plate laminated to a liquid crystal cell 9 on the polarizing layer 5 side is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate, a method for manufacturing the same, and a liquid crystal display using the polarizing plate.

[0002]

2. Description of the Related Art Liquid crystal display devices include notebook personal computers, word processors, monitors for desk-top personal computers, liquid crystal projectors, liquid crystal televisions, digital cameras, small calculators, watches, electronic organizers, personal digital assistants, amusement devices, It is widely used in stationery, mobile phones, car navigation systems, home appliances such as rice cookers, air conditioners, and microwave ovens. Along with this, demands for a polarizing plate, which is an essential component of a liquid crystal display device, have been diversified.

A polarizing plate is usually made of a polyvinyl alcohol-based resin film with iodine or a dichroic direct dye adsorbed and oriented, and a transparent protective film such as a triacetyl cellulose film is provided on both sides of an iodine-based polarizing film or a dye-based polarizing film. It is common to paste the, the thickness,
The thickness is around 6 to 30 μm for the polarizing film layer made of polyvinyl alcohol resin alone, and around 100 to 190 μm when the layer of the transparent protective film is added. Such a polarizing film is manufactured, for example, by uniaxially stretching a polyvinyl alcohol-based resin film, adsorbing and orienting a dichroic direct dye having iodine or an azo group, and immersing in a boric acid-containing aqueous solution. .

[0004] Among liquid crystal display devices, portable liquid crystal display devices such as mobile phones, electronic organizers, and personal digital assistants are known.
It is required to be lighter and thinner, and there is an increasing demand for further reduction in the thickness of polarizing plates used therein. In addition, so-called reflective polarizers and transflective polarizers that take in external light and use for display are often used in portable liquid crystal display devices. As a reflection plate or a semi-transmission reflection plate to be used, a matte-treated film having a thickness of about 50 μm is coated with aluminum or silver on one side to form a scattering reflection plate or a semi-transmission reflection plate, or a mirror reflection reflection plate. A combination of a reflector or a transflector and a diffusion layer,
well known. However, such a reflective polarizing plate or a transflective polarizing plate has a problem that the thickness is so large that parallax is easily generated. Therefore, a thinner reflective polarizing plate or a transflective polarizing plate is required.

As a thin polarizing plate, there is known a polarizing plate in which an aqueous solution containing a dye is coated on a substrate to form a polarizing layer. For example, JP-A-3-54506 discloses that after a substrate is rubbed, a corona treatment is performed, and a bar-shaped dichroic direct dye is applied thereon to orient the dichroic dye in the rubbing direction. A polarizing plate having a polarizing layer having a structure is disclosed. However, the polarizing plate thus obtained has insufficient polarizing performance, and has not been put to practical use. In addition, International Patent Application Publication WO 96/16015 (= US 6,049,428) states that
Disclosed is that a supramolecular structure is formed by adding a hydrophilic group to a tabular dye to prepare an aqueous solution, and an aqueous solution containing the supramolecular structure is applied to a substrate to form a polarizing plate. Have been. The polarizing plate disclosed herein has improved polarization performance over the conventional coating-type polarizing plate, but the polarization performance is still not sufficient, and the transmittance and contrast are required to be further improved. I have.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to adopt a polarizing layer formed by applying an aqueous solution containing a plate-like dye, to reduce the thickness and improve the degree of polarization. Accordingly, it is an object of the present invention to provide a thin polarizing plate excellent in contrast. Another object of the present invention is
An object of the present invention is to provide a thin liquid crystal display device using the polarizing plate.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, rubbed the substrate and applied a solution containing a plate-like dye to the rubbed surface. As a result, the inventors have found that a polarizing plate which is thin and exhibits high polarization performance can be obtained, and has completed the present invention.

That is, according to the present invention, there is provided a substrate, and a polarizing layer formed on at least one surface of the substrate,
The polarizing layer has a thickness of 20 to 1,500 nm, and is formed by rubbing at least one surface of the substrate, applying an aqueous solution containing a plate-like dye to the rubbed surface, and drying. Polarizing plate is provided. If such a polarizing layer is formed on one surface of the substrate and a reflective layer is arranged on the other surface, a reflective polarizing plate can be obtained. Alternatively, a reflective polarizing plate can be obtained by adopting a substrate having a reflective layer on one surface and forming the above-mentioned polarizing layer on the reflective layer. In these reflective polarizing plates, a light diffusion layer can be further provided on the polarizing layer.

Further, according to the present invention, in forming a polarizing layer by applying an aqueous solution containing a dye to at least one surface of a substrate, the aqueous solution containing a dye is an aqueous solution containing a plate-like dye. There is also provided a method for producing a polarizing plate by subjecting a surface to be rubbed to a rubbing treatment, and then applying the dye-containing aqueous solution to the rubbed treatment surface and drying. Thus, before the application of the dye-containing aqueous solution,
By performing a rubbing treatment on the coated surface of the substrate, the orientation of the dye is improved, and the degree of polarization of the polarizing layer obtained after drying is improved.

Further, according to the present invention, the above-mentioned polarizing plate comprises:
A liquid crystal display device stacked on a liquid crystal cell on the polarizing layer side is also provided. Here, if a reflective polarizing plate having the above-described reflective layer is used as the polarizing plate, a reflective or transflective liquid crystal display device can be obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
In the present invention, the substrate on which the polarizing layer is formed is usually transparent, and generally a transparent resin film is preferably used. For example, a cellulose resin film, a polyester resin film, a polyolefin resin film, an acrylic resin film, a polycarbonate resin film, a polyarylate resin film, a polyethersulfone resin film, or the like can be used.

As the cellulose resin film, specifically, a cellulose acetate resin is preferable, and examples thereof include a triacetyl cellulose film and a diacetyl cellulose film. Examples of the polyester resin film include a polyethylene terephthalate film, a polyethylene naphthalate film, and a polybutylene terephthalate film. The polyolefin-based resin film is preferably an amorphous (amorphous) film, and particularly preferably a film having a polymerized unit of a cyclic olefin such as norbornene or a polycyclic norbornene-based monomer. Further, a copolymer of a cyclic olefin and a chain olefin may be used. Among them, a film made of a norbornene-based resin is advantageously used. Norbornene-based resins in which a polar group is introduced are also effective. The polycarbonate resin film may be a homopolymer or a copolymer. On the other hand, other than the resin film, a glass plate or a metal plate may be used as the substrate.

The thickness of the substrate is preferably as thin as possible. However, if the thickness is too small, the workability is inferior. For example, the thickness is about 10 to 150 μm, preferably 20 μm or more, more preferably 30 μm or more, and preferably 100 μm or less. ,
More preferably, it is 90 μm or less. The transparent resin of the substrate may contain an ultraviolet absorber or the like.

A commercially available resin film can be used as such a substrate. Examples of commercially available triacetyl cellulose films include "Konica UV80SF" sold by Konica Corporation and "Fujitac" film sold by Fuji Photo Film Co., Ltd.
Commercially available amorphous polyolefin-based resin films include, for example, “ESCINA” and “SCA40” sold by Sekisui Chemical Co., Ltd., “ARTON” sold by JSR Corporation, and Zeon ( "ZEONEX" and "ZEONOR" sold by Mitsui Chemicals, Inc., and "APO" and "Apel" sold by Mitsui Chemicals, Inc. Further, examples of commercially available polycarbonate resin films include “Pure Ace” and “Pure Ace WR” sold by Teijin Limited. These substrates are preferably non-oriented, for example, have a front retardation value of 100 nm or less, more preferably 50 nm or less.

This is not the case when a resin film having retardation characteristics is used as the substrate. This is not the case. For example, a viewing angle widening film such as “Fuji WVA” film sold by Fuji Photo Film Co., Ltd. "LC film" and "NH film" sold by Co., Ltd.
Has birefringence, but can be used as a substrate in the present invention. Also, Minnesota Mining and Manu
Brightening film "DBEF" manufactured by facturing (3M),
“TDF”, “BEF”, etc. (available from Sumitomo 3M Limited in Japan) can be used as the substrate in the present invention.

In the present invention, a polarizing layer is formed by applying an aqueous solution containing a plate-like dye to at least one surface of such a substrate. Prior to this, a rubbing treatment is performed on the surface of the substrate to be coated. Apply. The rubbing treatment referred to herein is a treatment of rubbing the surface, and by performing this treatment, some orientation acts on the substrate surface, and the orientation of the dye in the aqueous solution containing the plate-like dye applied thereafter is changed. It is estimated that the direction is almost constant.

For the rubbing treatment, for example, a method of rubbing the substrate surface with velvet or velvet cloth can be employed. As the type of cloth used for rubbing, for example,
Rayon, cupra, nylon, cotton, felt and the like can be mentioned. The cloth may be wound around a roll and rubbed while rotating, or the cloth may be fixed and the substrate may be moved and rubbed. The rubbing treatment is performed in a certain direction on the substrate surface. The rubbing treatment requires rubbing at least once, and may be rubbed several times.
Furthermore, you may rub by reciprocating in a fixed direction.

When a long film is subjected to a rubbing treatment, it is preferable to perform a rubbing treatment while pressing the substrate film against the cloth. At this time, the direction of rotation of the roll when the cloth is wound around the roll may be the forward direction or the reverse direction of the running direction of the substrate film, and the roll may be fixed. Is preferably in the positive direction because uniform processing is easily performed.

On the substrate subjected to the rubbing treatment, an aqueous solution containing a plate-like dye is applied to the rubbed surface to form a polarizing layer. Suitable dyes include, for example, anthraquinone, phthalocyanine, porphyrin, naphthalocyanine, quinacridone, dioxazine, indanthrene, acridine, perylene, pyrazolone, acridone, pyranthrone, and isobiolan. Tabular dyes such as tron-based dyes can be used. More specifically, Japanese Patent Publication No. Hei 8-511109 (= WO
94/28073 = US 5,739,296) and International Patent Application Publication WO 96
/ 16015 (= US 6,049,428). Examples of typical tabular or elliptic pigments include those represented by the following structural formula.

[0020]

Here, R is, for example, hydrogen, halogen,
R 'can be, for example, hydrogen, nitro, a carboxylic acid group or a sulfonic acid group; it can be hydroxyl, alkoxy, phenylamino unsubstituted or substituted with chlorine or sulfonic acid, or anthraquinone-1-ylamino. R "can be, for example,

[0022]

Wherein X is O, CH
₂ , NH, CONH, NHCONH or CH = CH, Z is hydrogen, methyl, methoxy, carboxylic acid or sulfonic acid; Y can be, for example, hydrogen or sulfonic; The wavy lines appearing at both ends of the symbol mean that the structural unit between them repeats; the sulfonic acid group and carboxylic acid group here may be in the form of a salt in addition to the free acid.

When these dyes do not have a hydrophilic group, those having a structure in which a hydrophilic substituent, for example, at least one sulfonic acid group is introduced, are used. A plate-like dye having a hydrophilic group introduced in this way is
Used by dispersing or dissolving in water. These are amphiphilic substances that exhibit a lyotropic liquid crystal phase, that is, a liquid crystal phase that transitions between a liquid crystal state and a complete solution state depending on the concentration in a solution. The above-mentioned Japanese Patent Publication No. Hei 8-511109 and International Patent Application Publication No. WO 96/16015 disclose many dyes in which a sulfonic acid group which is a hydrophilic group is introduced. The aqueous solution containing a dye preferably contains a surfactant in addition to the above-mentioned plate-like dye. Suitable surfactants include, for example, polyethylene glycol and “Trit”.
on X-100 "(a nonionic surfactant sold by Rohm and Haas Co.). An aqueous solution containing such a plate-like dye and suitable for forming a polarizing layer is:
Available from Optiva, USA.

The application of the aqueous solution containing the tabular dye can be carried out by a general method, for example, various coating methods such as Meyer bar coating, gravure coating, die coating, dip coating, spray coating, and screen printing. And a printing technique such as an inkjet method. In particular, a coating method in which a shear stress is applied is preferable. After the application, the polarizing layer can be formed by evaporating the solvent water. The solvent can be evaporated by a usual drying method, for example, heat drying, room temperature drying, freeze drying, far infrared drying and the like are used. The thickness of the obtained polarizing layer is 20
It can be as thin as ~ 1,500 nm. This thickness is preferably 50 nm or more, and more preferably
0 nm or less, and is appropriately selected depending on the type of the tabular dye and the transmittance of the obtained polarizing plate.

In the polarizing plate thus obtained, the molecules of the plate-like dye are oriented in a direction substantially perpendicular to the direction of the rubbing performed before coating. In the prior art, the dye molecules were oriented substantially in alignment with the rubbing direction. However, when the tabular dye was used, it was surprisingly orthogonal, and a result different from that of the prior art was obtained. Although the reason for this is not clear, as described above, it is assumed that the rubbing treatment exerts some orientation on the substrate surface, and that the orientation of the dye to be applied thereafter becomes substantially constant.

The polarizing plate of the present invention is similar to the conventional polarizing plate.
A liquid crystal display device can be provided by disposing the liquid crystal cell on one surface or both surfaces. This polarizing plate can be used for both the front polarizing plate and the back polarizing plate of the liquid crystal cell. When used as a rear polarizing plate of a liquid crystal cell,
The liquid crystal cell is laminated on the polarizing layer side of the polarizing plate. When the polarizing plate obtained by the present invention is applied to a plastic liquid crystal cell or a film liquid crystal cell in which two polymer films are arranged to face each other to form a liquid crystal display device, The polarizing plate of the present invention may be affixed thereto, or the polymer film itself constituting the liquid crystal cell may be formed by forming a thin polarizing layer on the surface of a substrate according to the present invention.

The polarizing plate of the present invention is particularly effective for a reflective polarizing plate which is required to be thin. An example in which this polarizing plate is applied to a reflective polarizing plate will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing one embodiment of this case. In this example, a reflective layer 3 is provided on one surface of a substrate 1.
Is formed, and the polarizing layer 5 formed by the method described above is located on the other surface. In this case,
On the surface of the polarizing layer 5 opposite to the substrate 1, as shown in FIG.
A light diffusion layer 7 can also be provided. When a reflective polarizing plate is used, the substrate 1 may be a translucent or milky resin film.

FIG. 3 is a schematic sectional view showing another embodiment in which the polarizing plate according to the present invention is applied to a reflective polarizing plate. In this example, a reflecting layer 3 is provided on one surface of a substrate 1. Provided,
The polarizing layer 5 is formed directly on the surface of the reflective layer 3. In this case, the substrate 1 and the reflective layer 3 provided on the surface thereof may be regarded as the substrate in the present invention as a whole. Therefore, in this case, the reflective layer 3 is formed on the surface of the substrate 1, the surface of the reflective layer 3 is rubbed, and then the polarizing layer 5 is formed on the rubbed surface by the method described above.
To form Further, a light diffusing layer 7 can be provided on the surface of the polarizing layer 5 opposite to the surface in contact with the reflecting layer 3 as shown in FIG.

In the embodiment shown in FIGS. 1 to 4, the reflection layer 3 is preferably formed of a metal layer so that light is reflected well. Such a metal layer can be provided, for example, by forming a layer made of a metal having a high reflectance such as aluminum or silver. For the formation of the metal layer, for example, an ordinary method used for forming a metal thin film, such as a vacuum evaporation method, a sputtering method, and an ion plating method, can be adopted. The thickness of the reflective layer 3 is usually 10 to 100.
If it is on the order of nm, it shows a practically sufficient reflectance. Reflective layer 3
May have a certain degree of transmissivity to form a transflective layer. The thickness of the metal layer for imparting transparency is usually about 10 to 30 nm.

When a silver layer is provided as a metal layer by a vapor deposition method or the like, a protective layer is preferably provided above and / or below the metal layer in order to prevent deterioration of the metal layer. The protective layer is not particularly limited, and examples thereof include a coating film of an acrylic resin, an epoxy resin, a polyester resin, a urethane resin, or an alkyd resin. These protective coating films can be provided by a usual method such as roll coating, gravure coating, spray coating and the like. Also,
Inorganic thin films such as aluminum oxide and silicon oxide,
It can be used as a protective layer. When such a protective layer is provided, its thickness is usually in the range of about 5 nm to 20 μm.

The reflection surface of the reflection layer 3, that is, the boundary surface with the substrate 1, may be roughened. For example, the surface can be roughened by a method of sandblasting the surface of the substrate 1 before forming the reflective layer 3 or a method of coating the surface of the substrate 1 with a coating liquid containing inorganic or organic fine particles. . Alternatively, since a resin film obtained by flattening a resin mixed with an inorganic filler by extrusion or the like has a roughened surface, such a resin film can be used as a roughened substrate.

When the reflecting surface of the reflecting layer 3 is a flat mirror surface, as shown in FIG. 2 or 4, a light diffusing layer 7 made of a resin mixed with inorganic fine particles and / or organic fine particles is provided on the polarizing layer 5. May be provided. Inorganic fine particles used in this case, for example, in addition to silica, calcium carbonate, and the like,
Pearl pigments such as synthetic or natural mica coated with titanium dioxide, plate-like fish scale foil, pearlescent fine particles such as hexagonal plate-like basic lead carbonate and the like, and organic fine particles, for example, polymethyl Examples include acrylic beads such as methacrylate beads, polystyrene beads such as crosslinked polystyrene beads, polycarbonate beads, melamine / formaldehyde resin beads, benzoguanamine / formaldehyde resin beads, and organic silica beads. These fine particles may be used alone or in combination of two or more. The particle size of the fine particles is not particularly limited, but is, for example, about 0.1 to 50 μm, preferably about 1 to 20 μm, and more preferably about 1 to 10 μm. The resin for forming the light diffusion layer 7 is not particularly limited, but examples thereof include an acrylic resin, a urethane resin, an epoxy resin, a polyester resin, and an alkyd resin. These resins may have adhesive properties.

The combination of the fine particles and the resin binder is appropriately selected, but it is preferable to select a combination such that the difference in refractive index between the two is 0.01 to 0.5. The mixing ratio of the fine particles and the resin binder is not particularly limited, but usually, for example, the fine particles are contained in an amount of 0.1 to 100 parts by weight of the resin binder.
It is blended so as to be from 01 to 70 parts by weight. When the light diffusion layer 7 is provided, its thickness is usually about 1 to 100 μm,
Preferably it is about 5 to 30 μm.

In order to form the light diffusing layer 7, for example, fine particles and a resin are mixed and then applied by a usual method such as roll coating, gravure coating, or spray coating. Further, the light diffusion layer 7 can be provided by laminating films having light diffusion characteristics. As the light diffusing film used in this case, the same inorganic fine particles and / or organic fine particles and resin as described above are used, and a film obtained by casting a resin mixed with fine particles, a resin mixed with fine particles is used. Examples of the film include a film obtained by coating the substrate film surface and then peeling from the substrate film, a film obtained by embossing the surface of the film, and a film obtained by heat or light curing a mixture of resins having different refractive indexes. Such a light diffusing film may have a haze value of 5 to 99%, for example. The method for laminating the films is not particularly limited. For example, the films may be laminated by an ordinary method using an acrylic adhesive or the like.

The reflective polarizing plate thus obtained can be laminated on the back surface of the liquid crystal cell (the surface opposite to the viewing side) to form a liquid crystal display device. At this time, as illustrated in FIGS. 5 to 8, the liquid crystal cell is laminated on the polarizing layer 5 side of the reflective polarizing plate. FIG. 5 is a schematic cross-sectional view showing an example in which a polarizing plate of the type shown in FIG. 1 is laminated on a liquid crystal cell 9 on the polarizing layer 5 side to form a liquid crystal display device. FIG. 6 is a schematic cross-sectional view showing an example in which a polarizing plate of the type shown in FIG. 2 is stacked on a liquid crystal cell 9 on the polarizing layer 5 side (light diffusion layer 7 side) to form a liquid crystal display device. . FIG. 7 is a schematic cross-sectional view showing an example in which a polarizing plate of the type shown in FIG. 3 is laminated on a liquid crystal cell 9 on the polarizing layer 5 side to form a liquid crystal display device. FIG.
FIG. 5 is a schematic cross-sectional view showing an example in which a polarizing plate of the type shown in FIG. 4 is laminated on a liquid crystal cell 9 on the polarizing layer 5 side (light diffusion layer 7 side) to form a liquid crystal display device.

A retardation plate may be provided between the liquid crystal cell 9 and the polarizing layer 5 or the light diffusing layer 7 of the reflective polarizing plate, if necessary. Further, another polarizing plate (not shown) may be arranged on the front surface side of the liquid crystal cell 9 (the side opposite to the surface on which the reflective polarizing plate is arranged). The front-side polarizing plate may include a normal polyvinyl alcohol-based polarizer, and according to the present invention, a coating type dye-based polarizing layer having a thickness of 20 to 1,500 nm on a transparent substrate. If the provided polarizing plate is used, the thickness can be further reduced. In the latter case, prior to forming the dye-based polarizing layer,
Rubbing the surface on which the transparent substrate is coated is more effective because it results in a polarizing plate having high polarization performance. When a polarizing plate having a coating type dye-based polarizing layer formed on a transparent substrate is used as a front-side polarizing plate, the polarizing plate is usually arranged so as to be the outermost surface. The front side of the liquid crystal cell also
A retardation plate can be arranged as needed.

[0039]

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

Single transmittance Ts at an arbitrary wavelength λ
(Λ), parallel transmittance Tp (λ) and orthogonal transmittance Tc (λ)
Was calculated using the following equations (1), (2) and (3). Ts (λ) = [K (λ) + L (λ)] / 2 (1) Tp (λ) = [{K (λ)} ² + {L (λ)} ² ] / 2 (2) Tc (λ ) = K (λ) × L (λ) (3)

Here, K (λ) is the spectral transmittance when linearly polarized light of wavelength λ is incident in the transmission axis direction of the polarizing plate, and L (λ) is the wavelength of the wavelength λ in the absorption axis direction of the polarizing plate. This is the spectral transmittance when linearly polarized light is incident.
(Λ) and L (λ) were measured using a spectrophotometer “Shimadzu UV-2200” manufactured by Shimadzu Corporation.

The spectral transmittance τ (λ) obtained at every 10 nm in the wavelength region of 400 to 700 nm (the above-mentioned single transmittance Ts (λ), parallel transmittance Tp (λ), and orthogonal transmittance Tc ( λ)), the luminosity correction transmittance T (the luminosity correction single transmittance Ts, the luminosity correction parallel transmittance Tp, and the luminosity correction orthogonal transmittance Tc) was calculated by the following equation (4).

[0043]

Here, P (λ) represents the spectral distribution of the standard light (C light source), and y (λ) represents the 2 degree visual field color matching function.

The degree of polarization P was determined from the luminosity-corrected parallel transmittance Tp and the luminosity-corrected orthogonal transmittance Tc by the following equation (5). P = [(Tp−Tc) / (Tp + Tc)] ^1/2 (5)

Example 1 A rubbing treatment was performed on a surface of a polyethylene terephthalate film having a thickness of about 75 μm (obtained from Toray Industries, Inc.) by rubbing a velvet cloth five times on a rubbing treatment device. An aqueous solution ("LCP N013" obtained from Optiva) containing a dye having a flat plate structure was applied to the rubbed surface.
Using a No. 3 No. 3 Meyer bar, coating speed 100 mm /
After applying for sec, leave at room temperature (20 ° C) for 30 minutes,
Let dry. The thickness of the polarizing layer after drying was about 500 nm. The overall thickness of the obtained polarizing plate was 75.5 μm, the degree of polarization P was 84.0%, and the single transmittance Ts was 41.2%.
It was thinner than a conventional polarizing plate and showed good polarization performance.

Comparative Example 1 A polarizing plate was produced in the same manner as in Example 1 except that the surface of the polyethylene terephthalate film was not subjected to a rubbing treatment. The polarization degree P of the obtained polarizing plate is 8
0.1% and single transmittance Ts were 40.8%.

Example 2 Using a No. 5 No. 5 Meyer bar, a coating speed of 200 mm /
A polarizing plate was produced in the same manner as in Example 1 except that the coating was performed in sec. The polarization degree P of the obtained polarizing plate is 9
4.4% and the single transmittance Ts were 36.0%, showing good polarization performance.

Comparative Example 2 A polarizing plate was produced in the same manner as in Example 2, except that the surface of the polyethylene terephthalate film was not subjected to a rubbing treatment. The polarization degree P of the obtained polarizing plate is 9
0.8% and the single transmittance Ts were 36.3%.

Example 3 Rubbing treatment was performed by rubbing a velvet cloth five times on the surface of a norbornene resin film (“SCA50” sold by Sekisui Chemical Co., Ltd.) with a thickness of about 50 μm on a rubbing treatment device. An aqueous solution containing a pigment having a flat plate structure (“LCP N0015” available from Optiva) was applied to the rubbed surface of the rubbed surface with a Meyer bar No. 5
Is applied at a coating speed of 50 mm / sec, left at room temperature (20 ° C.) for 30 minutes and dried to obtain a polarizing plate having a polarizing layer having a thickness of about 1,000 nm. When a reflective layer is formed by evaporating aluminum to a thickness of about 60 nm on the surface of the film with the polarizing layer opposite to the surface on which the polarizing layer is formed, an ultra-thin reflective polarizing plate having a thickness of about 50 μm is obtained. A diffusion adhesive is applied to the polarizing layer side surface of the reflective polarizing plate, and bonded to the lower surface of the TN type liquid crystal cell via the adhesive, and a polyvinyl alcohol / iodine type polarized light is applied to the upper surface of the TN type liquid crystal cell. When a plate, "SQ1852A" available from Sumitomo Chemical Co., Ltd., is bonded via an adhesive, a TN type liquid crystal display device is obtained. This TN
The liquid crystal display device can be made thin, has a small parallax, and is easy to see.

[0051]

According to the present invention, a polarizing plate which is very thin, has a high degree of polarization, and thus has excellent contrast can be obtained. Therefore, the polarizing plate of the present invention can be suitably used for a liquid crystal display device of a portable electronic device, for example, a mobile phone, a portable information terminal, a smart card, an IC card, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example in which the polarizing plate of the present invention is applied to a reflective polarizing plate.

FIG. 2 is a schematic cross-sectional view showing another example in which the polarizing plate of the present invention is applied to a reflective polarizing plate.

FIG. 3 is a schematic sectional view showing another example in which the polarizing plate of the present invention is applied to a reflective polarizing plate.

FIG. 4 is a schematic sectional view showing still another example in which the polarizing plate of the present invention is applied to a reflective polarizing plate.

FIG. 5 is a schematic cross-sectional view showing an example in which the polarizing plate of FIG. 1 is laminated on a liquid crystal cell.

FIG. 6 is a schematic cross-sectional view showing an example in which the polarizing plate of FIG. 2 is laminated on a liquid crystal cell.

FIG. 7 is a schematic sectional view showing an example in which the polarizing plate of FIG. 3 is laminated on a liquid crystal cell.

8 is a schematic cross-sectional view showing an example in which the polarizing plate of FIG. 4 is laminated on a liquid crystal cell.

[Explanation of symbols]

 1 ... substrate, 3 ... reflection layer, 5 ... polarization layer, 7 ... light diffusion layer, 9 ... liquid crystal cell.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 BA02 BA26 BA27 BB03 BB42 BB43 BB44 BB49 BB51 BB63 BC04 BC14 BC22 2H091 FA08Z FA14Z FA31Z FB02 FB08 FB12 FB13 FC02 FC21 FD06 GA01 LA11 LA17 MA10

Claims (12)

[Claims] 1. A substrate comprising: a substrate; and a polarizing layer formed on at least one surface of the substrate, wherein the polarizing layer has a thickness of 20 to
A polarizing plate, which is formed by rubbing at least one surface of the substrate, applying an aqueous solution containing a plate-like dye to the rubbed surface, and drying. . 2. The polarizing plate according to claim 1, wherein the substrate is a cellulose resin film. 3. The polarizing plate according to claim 1, wherein the substrate is a polyester resin film. 4. The polarizing plate according to claim 1, wherein the substrate is a norbornene resin film. 5. The method according to claim 1, wherein the tabular dye is an anthraquinone dye, a phthalocyanine dye, a porphyrin dye, a naphthalocyanine dye, a quinacridone dye, a dioxazine dye, an indanthrene dye, an acridine dye, a perylene dye, or a pyrazolone. The polarizing plate according to any one of claims 1 to 4, wherein the polarizing plate is selected from the group consisting of a dye, an acridone dye, a pyranthrone dye, and an isoviolanthrone dye. 6. The polarizing plate according to claim 1, wherein the tabular dye has a hydrophilic group. 7. The polarizing plate according to claim 1, wherein the molecules of the plate-like dye are oriented in a direction substantially perpendicular to the rubbing direction. 8. A method for applying a dye-containing aqueous solution to at least one surface of a substrate to form a polarizing layer, wherein the dye-containing aqueous solution is an aqueous solution containing a plate-like dye, and A method for producing a polarizing plate, comprising performing a rubbing treatment, then applying the dye-containing aqueous solution to the rubbed surface, and drying. 9. The method according to claim 8, wherein the dye-containing aqueous solution is an aqueous solution containing a plate-like dye into which a hydrophilic group is introduced. 10. A liquid crystal display device comprising the polarizing plate according to claim 1 laminated on a liquid crystal cell on the polarizing layer side. 11. The liquid crystal display device according to claim 10, wherein a front polarizing plate is disposed on a liquid crystal cell surface opposite to a surface on which the polarizing plates are laminated. 12. A front polarizing plate having a thickness of 20 mm on a transparent substrate.
12. The liquid crystal display device according to claim 11, wherein a dye-based polarizing layer having a thickness of from 1,500 nm is formed.