JP3060744B2 - Phase difference plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retardation plate.

[0002]

2. Description of the Related Art A retardation plate using a polymer film having uniaxial orientation is used as an optical compensator for improving the display quality of a liquid crystal display device.

However, an STN type liquid crystal display using such a retardation plate as an optical compensator is lighter, thinner and less expensive than a two-layer STN type liquid crystal display using a liquid crystal cell as an optical compensator. On the other hand, it has advantages such as
It has drawbacks such as poor viewing angle characteristics and poor black and white levels. The inferior black and white level has been considerably improved by a method such as laminating two retardation plates, but the viewing angle characteristics are still not sufficient.

[0004] To evaluate the viewing angle characteristics, the viewing angle is used in the case of a birefringent film having a uniaxial orientation. Viewing angle is a slow axis in the case of a birefringent film with a positive refractive index anisotropy, and a birefringent film with a negative refractive index anisotropy in a polarizing microscope equipped with a Senarmont compensator. In the case of, the fast axis is the rotation axis respectively,
The tilt angle (θ _1.10 ) when the ratio (R / R ₀ ) of the retardation (R) measured in a state where the film is inclined to the retardation (R ₀ ) measured in a horizontal state is 1.10 It is defined that the larger the viewing angle, the better the viewing angle characteristics.

As a method of increasing the viewing angle, a method of shrinking a film in a direction perpendicular to a stretching axis at the time of uniaxial stretching (Japanese Patent Laid-Open No. 2-191904) is described in which a polymer liquid is formed under application of an electric field. Method for controlling birefringence characteristics by stretching a film (JP-A-2-2853)
No. 03) and a method of laminating a film formed under application of an electric field on a conventional retardation plate (Japanese Patent Application Laid-Open No. 3-85519) has been proposed. Is hard to say.

In addition, in order to improve display characteristics such as contrast, hue, and viewing angle characteristics, various liquid crystal display methods other than the STN method (for example, a TN liquid crystal display method having a birefringence compensation layer (UK Patent No. 1462978)) Liquid crystal display system having a birefringent compensation layer and a birefringent compensation layer:
However, in these liquid crystal display systems, there is no anisotropy of the refractive index in the film plane (R ₀ = 0) and the refractive index in the film plane and the thickness direction of the film are different. A retardation plate having a different refractive index is required as an optical compensator.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve such problems, and as a result, have found that a novel retardation plate having excellent performance can be obtained by using an inorganic layered compound. The present invention was completed by adding various ideas.

That is, the present invention relates to a retardation plate using an inorganic layered compound layer having a different refractive index in a plane and a refractive index in a thickness direction.

The inorganic layered compound used in the present invention has a layered structure in which unit crystal layers are stacked on each other, and the bonding between the unit crystal layers is relatively weak, so that the structure of the unit crystal layer is not destroyed. A material capable of inserting ions and molecules between the unit crystal layers by various physical and chemical methods, and has a property that an in-plane refractive index and a refractive index in a thickness direction are different.

Such an inorganic layered compound is described in "Development and Application of Intercalation Compound" (edited by Chuzo Kato and Kazuyuki Kuroda, published by CMC Co., Ltd., 1985). For example, clay minerals, chalcogenides, phosphorus Zirconium oxylates, transition metal oxylates, layered polysilicates, metal oxyhalides, and interlaminar modified products in which ions or molecules are inserted between their unit crystal layers. When an inorganic layered compound having a refractive index larger than the above is used, an inorganic layered compound layer having an in-plane refractive index larger than the refractive index in the thickness direction can be obtained. In the present invention, clay minerals are preferably used, but clay minerals are classified into two types.

In the first type, aluminum or magnesium is used as the central metal on the tetrahedral layer of silica.
The second type is a type having a unit crystal layer composed of a two-layer structure having a tetrahedral layer. The second type is a type in which a tetrahedral layer of silica has a central metal of aluminum, magnesium, or the like.
This is a type having a unit crystal layer composed of a three-layer structure in which both sides of a face layer are sandwiched. The first type includes a kaolinite group and an antigolite group, and the second type includes a smectite group, a vermiculite group, and a mica group depending on the number of ion exchange cations.

Specific examples of clay minerals include kaolinite, dickite, nacrite, halloysite, antigolite, chrysotile, pyrophyllite, montmorillonite, hectorite, sodium 4 silicon mica, sodium teniolite, muscovite, and margarite. ,talc,
Vermiculite, phlogopite, zansophyllite, chlorite and the like.

Among the clay minerals, sodium tetrasilicic mica and a smectite group, which are chemically synthesized and contain few impurities, are preferable because of their excellent transparency and the like. As the smectite group, montmorillonite, beidellite, nontronite, saponite, hectite Light, sauconite and chemically synthesized products having a crystal structure similar to them can be exemplified.

A layer obtained by swelling or dispersing the inorganic layered compound is laminated on a substrate having a releasable property, for example, a polyester film having a surface subjected to a release treatment, by coating or the like, and then dried and peeled off. It is easy to manufacture an inorganic layered compound layer having a refractive index structure in which R ₀ = 0 without in-plane refractive index anisotropy and in-plane refractive index is different from the refractive index in the thickness direction. And can be used as a retardation plate of the present invention.

The solvent used for swelling or dispersing the inorganic layered compound is preferably a solvent which swells between the layers of each unit crystal layer of the inorganic layered compound, and especially a solvent which can swell between the unit crystal layers until it becomes colloidal. For example, in the case of a clay mineral in which the unit crystal layer is not modified with an organic substance, dimethylformamide, dimethylsulfoxide, nitromethane, water, methanol, ethylene glycol and the like can be used.

In order to improve the transparency after film formation, it is preferable to use an inorganic layered compound containing no impurities and having a particle size of 5 μm or less. A synthetic smectite group whose particle size is controlled to be equal to or less than the wavelength of visible light is preferred in these respects, and among them, synthetic hectorite is preferred.

In producing a retardation plate using the inorganic layered compound layer of the present invention, mixing an optically transparent resin with the inorganic layered compound requires not only film forming properties but also mechanical properties and properties. It is preferable because durability is improved.

The optically transparent resin to be mixed is not particularly limited, and can be appropriately selected from a hydrophobic resin and a hydrophilic resin depending on the type of the inorganic layered compound. A single resin or a blend of a plurality of resins may be used. If so, a resin additive may be contained.

The ratio of the inorganic layered compound to the optically transparent resin is not particularly limited, but the volume ratio of the inorganic layered compound to the optically transparent resin is preferably in the range of 0.1 to 10.
It is preferable for improving mechanical properties such as film forming property and preventing cracking of the inorganic layered compound layer.

As a method of forming a film obtained by mixing an inorganic layered compound and an optically transparent resin, a structure in which the unit crystal layers of the inorganic layered compound are widened after the film formation and the resin occupies the unit crystal layers is adopted. The method is not particularly limited as long as the method can be performed.

For example, a method in which an inorganic layered compound and an optically transparent resin are hot-kneaded and extruded, and a method in which an inorganic layered compound swelled or dispersed in a solvent and an optically transparent resin are mixed and extruded. A method in which a solution obtained by swelling or dispersing an inorganic layered compound in a solvent and a solution obtained by dissolving an optically transparent resin are uniformly mixed to form a film by a casting method. Preferably, a method of forming a film by coating and drying a mixture obtained by uniformly mixing a solution swelled or dispersed in a resin and a solution in which an optically transparent resin is dissolved is applied.

When a clay mineral which can be swelled or dispersed in water is used as the inorganic layered compound, the hydrophilic resin may be a nonionic hydrophilic resin (polyvinyl alcohol, ethylene-vinyl alcohol copolymer, poly (vinyl alcohol), Polyvinyl alcohol polymers such as partially saponified vinyl acetate, cellulose, hydroxyethyl cellulose, cellulose polymers such as carbomethoxy cellulose, polyvinyl pyrrolidone, polyhydroxyethyl methacrylate,
Polyacrylamide, polyethylene glycol, etc.), cationic hydrophilic resins (polyethyleneimine, polyallylamine, N-alkylated products of polyvinylpyridine, chitosan, etc.) and anionic hydrophilic resins (polyacrylic acid,
Sodium polyacrylate, polystyrene sulfonic acid,
And the like can be used.

In order to improve the film-forming properties and to improve mechanical properties such as prevention of cracking of the inorganic layered compound layer, it is preferable to use a nonionic hydrophilic resin, especially a polyvinyl alcohol-based polymer. Degree 70% or more and degree of polymerization 2
Polyvinyl alcohol of 00 to 1800 is particularly preferable because it has excellent mixability with a clay mineral which can swell or disperse in water and transparency after film formation.

In the case of a mixture of an inorganic layered compound and an optically transparent resin, the optically transparent resin may be oriented at the time of film formation to cause birefringence. It is preferable to adjust the session value to 50 nm or less.

From the viewpoint of handling, the retardation film using the inorganic layered compound layer of the present invention is formed on a transparent substrate having no in-plane birefringence or having a very small in-plane birefringence. Thus, a retardation plate in a form laminated on a transparent substrate may be used. The transparent substrate has excellent transparency in the visible light region and does not have in-plane birefringence or has very low in-plane birefringence. For example, the in-plane retardation value is 50%.
Those having a thickness of not more than nm, which are optically uniform and capable of uniformly forming a liquid in which an inorganic layered compound is swollen or dispersed are used.

Examples of such a transparent substrate include a clean glass substrate, a transparent resin substrate produced by a cast film-forming method, and a cellulose-based film subjected to a surface saponification treatment. Cellulose-based films are preferred.

The method of laminating a retardation plate and a transparent substrate using the inorganic layered compound layer of the present invention includes, for example, a method of producing a film on a releasable substrate such as a surface-treated polyester film or a fluorine-processed stainless plate. A method of laminating by laminating the inorganic layered compound layer and various transparent substrates peeled off from the substrate with an adhesive, an adhesive or the like after the film is peeled off,
A method in which an inorganic layered compound is swollen or dispersed in a solvent, is cast on a transparent substrate to form a film, and the inorganic layered compound layer is laminated on the transparent substrate, and the inorganic layered compound is swollen or dispersed in a solvent and optically. Examples of a method in which a solution obtained by uniformly dissolving a solution in which a transparent resin is dissolved and a method of forming a film by a casting method and a method of extruding and laminating an inorganic layered compound layer on various transparent substrates can be exemplified. A method of uniformly mixing a swelled or dispersed material and a solution in which an optically transparent resin is dissolved, and applying and drying the film to form a film is preferable.

The retardation film using the inorganic layered compound of the present invention is intact or laminated on an optically transparent resin, and has no in-plane refractive index anisotropy and no in-plane refractive index. And a liquid crystal display device of a type that requires an optical compensator having a different refractive index in the thickness direction.

A retardation plate using the inorganic layered compound layer of the present invention becomes a retardation plate having good viewing angle characteristics by laminating on a birefringent film having a negative refractive index anisotropy. . A birefringent film having a negative refractive index anisotropy can be easily obtained by stretching a film made of a resin having a negative intrinsic birefringence. The stretching method may be any stretching method capable of obtaining uniform retardation, and a known method such as a tenter stretching method, an inter-roll stretching method, or an inter-roll compression stretching method can be used. As a method of lamination,
For example, a method similar to the above-described method of laminating on a transparent substrate can be used.

Although there are various resins having negative intrinsic birefringence, vinyl resins having a substituent having a high dielectric constant in a side chain are preferable, and among them, aromatic vinyl resins and acrylic resins have optical characteristics. Excellent and preferred. Specific examples of these include polystyrene, poly α-methylstyrene, polyvinyl pyridine, polyvinyl naphthalene, polymethyl methacrylate, and the like.

The retardation film thus obtained has excellent viewing angle characteristics and can be suitably used as an optical compensator for a liquid crystal display device of a type requiring viewing angle characteristics.

Incidentally, instead of using two retardation plates laminated on a birefringent film having a negative refractive index anisotropy with their optical axes shifted, instead of using an inorganic layered compound layer having a thicker thickness, One retardation plate laminated on a birefringent film having a negative refractive index anisotropy is prepared, and the inorganic layered compound layer is disposed between the two birefringent films having a negative refractive index anisotropy. For example, a retardation plate in which another birefringent film having a negative refractive index anisotropy is laminated thereon may be manufactured and used.

The method for mounting the retardation plate of the present invention to a liquid crystal display device is not particularly limited. One or both sides of the retardation plate are provided with an adhesive and bonded to a liquid crystal cell and / or a polarizing plate. And the like. Either surface of the retardation plate may be disposed on the liquid crystal cell side, or may be disposed between the upper polarizing plate and the liquid crystal cell or between the lower polarizing plate and the liquid crystal cell.

[0034]

The retarder of the present invention is easy to manufacture,
As a retardation plate with no in-plane birefringence and different in-plane refractive index and in-plane refractive index, used alone or in combination with other films, etc. to improve the display characteristics of various liquid crystal display devices can do.

[0035]

EXAMPLES The present invention will be described in detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. In the following examples, the particle size was measured using an ultrafine particle size analyzer BI-90 manufactured by Brookhaven.

Example 1 Polystyrene film (HR sheet, Dainippon Ink
Pulverized to make a 15% dichloroethane solution.
A film was formed by a casting method. This cast film
The film is stretched 2.8 times at 135 ° C.₀
= 512 nm, θ_{1. Ten}= 35 degrees, 28 μm thick birefringence
A functional film was obtained. This film is treated with a corona treatment machine (MM
Electrode type corona treatment test machine, manufactured by Softal Corporation
Processing energy 400W · min / m^Two Roller under the condition
After performing a surface treatment to a surface tension of 54 dyn / cm or more,
Synthetic smectite (trade name Smecton)
1% of SA, manufactured by Kunimine Industries: average particle size 108 nm)
An aqueous dispersion is applied and dried at about 28 ° C for 12 hours.
A birefringent polystyrene is applied to the mectite layer (thickness: 3.8 μm).
A retardation film laminated on a film was obtained. This retarder
Is R₀= Θ at 512 nm _1.10= Good viewing angle of 59 degrees
The characteristics were shown.

Example 2 A polystyrene cast film obtained in the same manner as in Example 1 was stretched 2.8 times at 135 ° C. by a tenter stretching method to obtain R ₀ = 503 nm, θ _1.10 = 35 °, and a thickness of 28 μm.
Was obtained. This film was subjected to corona treatment under the same conditions as in Example 1 to a surface tension of 54 dyn / cm or more, and then a synthetic hectorite (trade name: Laponite XLG), which is a clay mineral,
A 2% aqueous dispersion of Laporte (average particle size: 35 nm) is applied, dried at about 28 ° C. for 12 hours, and a retardation plate in which a synthetic hectorite layer (thickness: 10 μm) is laminated on a birefringent polystyrene film is used. Obtained. This phase difference plate is R ₀
At 506 nm, θ _1.10 = 80 ° or more, showing good viewing angle characteristics.

Example 3 Triacetyl cellulose film having a thickness of 80 μm (trade name: Fujitack Clear, Fuji Photo Film Co., Ltd.)
1% aqueous dispersion of synthetic smectite (trade name: Smecton SA, manufactured by Kunimine Kogyo Co., Ltd .: average particle size: 108 nm) which is a clay-based mineral, which has been subjected to a surface saponification treatment (manufactured by Nippon Steel Co., Ltd.) And dried at about 28 ° C. for 12 hours to form a synthetic smectite layer (thickness: 3.8 μm).
m) was laminated on a triacetyl cellulose film to obtain a retardation film. In the synthetic smectite layer, the difference between the in-plane refractive index and the refractive index in the thickness direction was 1.12 × 10 ⁻¹ , and the in-plane birefringence of the laminated retardation plates was extremely small (in-plane letter). 6 nm).

Example 4 By casting in the same manner as in Example 1, a cast polystyrene film having extremely low birefringence was obtained. This film was subjected to corona treatment under the same conditions as in Example 1 to a surface tension of 54 dyn / cm or more, and then sodium 4-silicic mica (trade name: Na-T) as a clay mineral
s, manufactured by Topy Industries: 0.65 having an average particle size of 977 nm)
% Aqueous dispersion was applied and dried at about 28 ° C. for 12 hours to obtain a retardation plate in which a sodium 4 silicon mica layer (2.5 μm thick) was laminated on a cast polystyrene film having extremely small birefringence. The difference between the in-plane refractive index and the thickness direction refractive index of the sodium 4 silicon mica layer was 2.14 × 10 ⁻¹ , and the in-plane birefringence of the laminated retardation plates was extremely small.

Example 5 A polystyrene cast film obtained in the same manner as in Example 1 was stretched 2.8 times at 135 ° C. by a tenter stretching method to obtain R ₀ = 503 nm, θ _1.10 = 35 °, and a thickness of 28 μm.
Was obtained. This film was subjected to corona treatment under the same conditions as in Example 1 to a surface tension of 54 dyn / cm or more, and then a synthetic hectorite (trade name: Laponite XLG), which is a clay mineral,
Water obtained by mixing 2: 1 aqueous dispersion of Laporte: average particle size 35 nm) and 2% aqueous solution of polyvinyl alcohol (polymerization degree 500, saponification degree 98.5%, manufactured by Wako Pure Chemical Industries) in a ratio of 1: 1. The dispersion was applied and dried at about 28 ° C. for 30 hours to obtain a retardation plate in which a polyvinyl alcohol-containing synthetic hectorite layer (18 μm in thickness) was laminated on a birefringent polystyrene film. This retardation plate has R ₀ = 503n
In m, θ _1.10 = 74 degrees, showing a good viewing angle characteristic, and the film formation state was extremely good.

Example 6 Triacetyl cellulose film having a thickness of 80 μm (trade name: Fujitack Clear, Fuji Photo Film Co., Ltd.)
) (Surface retardation of 6 nm) and synthetic hectorite (trade name: Laponite XLS (Laponite XL))
S), 5% of Laporte: average particle size 35 nm)
The aqueous dispersion obtained by mixing the aqueous dispersion and a 2.5% aqueous solution of polyvinyl alcohol (polymerization degree: 300, saponification degree: 98.5%, manufactured by Kuraray Co., Ltd.) in a ratio of 3: 7 was applied, and the mixture was applied at 60 ° C. After drying for 1 hour, a retardation plate in which a polyvinyl alcohol-containing synthetic hectorite layer (12 μm in thickness) was laminated on a triacetyl cellulose film was obtained. In the synthetic hectorite layer containing polyvinyl alcohol, the difference between the in-plane refractive index and the refractive index in the thickness direction was 0.18 × 10 ⁻¹ , and the in-plane birefringence of the laminated retardation plates was extremely small ( In-plane retardation 6 nm). The film formation state of this retardation plate was extremely good.

Example 7 Synthetic hectorite which is a clay mineral on a non-oriented glass plate
(Product name Laponite XLS (Laponite XL
S), 2 from Laporte: average particle size 35 nm)
% Aqueous dispersion and polyvinyl alcohol (polymerization degree 1000
A 1% aqueous solution with a saponification degree of 98.5% (produced by Kuraray Co., Ltd.)
The aqueous dispersion obtained by mixing at a ratio of 3: 7 is applied, and
After drying for 1 hour, synthetic alcohol containing polyvinyl alcohol
Retardation plate with a light layer (8 μm thick) laminated on a glass plate
I got Synthetic hectorite layer containing polyvinyl alcohol
Means that the difference between the in-plane refractive index and the thickness direction refractive index is 0.16 ×
10 ^-1And the in-plane birefringence of the laminated retarder
It was small. The film formation state of this phase difference plate is extremely good
It was good.

Example 8 Triacetyl cellulose film having a thickness of 80 μm (trade name: Fujitack Clear, Fuji Photo Film Co., Ltd.)
) (Surface retardation of 6 nm) and synthetic hectorite (trade name: Laponite XLS (Laponite XL))
S), 1% of Laporte: average particle size 35 nm)
The aqueous dispersion obtained by mixing the aqueous dispersion and a 0.5% aqueous solution of polyvinyl alcohol (polymerization degree: 2400, saponification degree: 98.5%, manufactured by Kuraray Co., Ltd.) in a ratio of 3: 7 is applied, and the mixture is applied at 60 ° C. After drying for 1 hour, the polyvinyl alcohol-containing synthetic hectorite layer (thickness: 10 μm) was
A retardation plate laminated on the film was obtained. The difference between the in-plane refractive index of the polyvinyl alcohol-containing synthetic hectorite layer and the refractive index in the thickness direction was 0.16 × 10 ⁻¹ , and the in-plane birefringence of the laminated retardation plates was extremely small (plane Within 6 nm). The film formation state of this retardation plate was good.

Example 9 A synthetic hectorite (trade name: Laponite X), which is a clay mineral, was placed on a surface-treated, release-resistant polyester film.
LS (LaponiteXLS), manufactured by Laporte: 2% aqueous dispersion of polyvinyl alcohol (polymerization degree 1000, saponification degree 88.5%)
An aqueous dispersion obtained by mixing a 1% aqueous solution (manufactured by Kuraray Co., Ltd.) at a ratio of 3: 7 was applied and dried at 60 ° C. for 1 hour. The synthetic hectorite layer containing polyvinyl alcohol is easily peeled off from the releasable polyester film, and the film thickness is 15 μm.
Was obtained from a synthetic hectorite layer containing polyvinyl alcohol. In this retardation plate, the difference between the in-plane refractive index and the thickness direction refractive index was 0.17 × 10 ⁻¹ , the in-plane birefringence was extremely small, and the film formation state was extremely good. .

Example 10 Triacetylcellulose film having a thickness of 80 μm (trade name: Fujitack Clear, Fuji Photo Film Co., Ltd.)
) (Surface retardation of 6 nm) and synthetic hectorite (trade name: Laponite XLG (Laponite XL))
G), 2% of Laporte: average particle size 35 nm)
An aqueous dispersion and a 2% aqueous solution of polyvinyl alcohol (polymerization degree 1000, saponification degree 88.5%, manufactured by Kuraray Co., Ltd.)
The aqueous dispersion obtained by mixing at a ratio of 7 was applied and dried at about 28 ° C. for 30 hours to form a polyvinyl alcohol-containing synthetic hectorite layer (thickness: 10 μm) using triacetyl cellulose.
A retardation plate laminated on the film was obtained. The difference between the in-plane refractive index and the thickness direction refractive index of the polyvinyl alcohol-containing synthetic hectorite layer was 0.17 × 10 ⁻¹ , and the in-plane birefringence of the laminated retardation plates was extremely small (plane Within 6 nm). The film formation state of this retardation plate was extremely good.

Example 11 A retardation plate was obtained in the same manner as in Example 6, except that the thickness of the synthetic hectorite layer containing polyvinyl alcohol was 2.4 μm. Next, a polystyrene resin (Sumibright E18)
3 Sumitomo Chemical Industries, Ltd.) 25% dichloroethane solution was prepared, and a film was formed by a casting method. This cast film is stretched 2.0 times at 130 ° C. by a tenter stretching method to obtain R ₀ = 403 nm, θ _1.10 = 38 degrees, and a thickness of 85 μm.
Was obtained. The retardation plate and the birefringent film using polystyrene were laminated using an adhesive so that the polyvinyl alcohol-containing synthetic hectorite layer was located between the triacetyl cellulose film and the birefringent film using polystyrene. Thus, a retardation plate was obtained. This retardation plate showed a good viewing angle characteristic of θ _1.10 = 51 degrees at R ₀ = 403 nm.

Example 12 The thickness of the synthetic hectorite layer containing polyvinyl alcohol was
Except for 7.2 μm, the retardation plate was made in the same manner as in Example 6.
I got This retardation plate is the same as that used in Example 11.
Using a birefringent film made of polystyrene and an adhesive
The synthetic hectorite layer containing polyvinyl alcohol
Using reacetylcellulose film and polystyrene
Phase difference plate
I got This retardation plate has an R₀= Θ at 403 nm _1.10=
Excellent viewing angle characteristics of 80 degrees or more were exhibited.

Comparative Example 1 A polystyrene cast film obtained in the same manner as in Example 1 was stretched 2.8 times at 135 ° C. by a tenter stretching method, and a retardation plate obtained was R ₀ = 503 nm and θ _1.10 = 35. Degree.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Koji Higashi 2-10-1, Tsukahara, Takatsuki-shi, Osaka Sumitomo Chemical Industries Co., Ltd. (72) Inventor Tadashi 2-10-1 Tsukahara, Takatsuki-shi, Osaka Sumitomo Sumitomo (56) References JP-A-3-85519 (JP, A) JP-A-58-149901 (JP, A) Motohiro and Taga, Thin film retardation plate by oblique application publication, Applied Application , July 1, 1989, vol. 28, no. 13, pages 2466 to 2482 (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 5/30 G02F 1/1335 510

Claims (7)

(57) [Claims] 1. A retardation plate comprising an inorganic layered compound layer having an in-plane refractive index and a refractive index in a thickness direction different from each other. 2. The inorganic layered compound layer is obtained by swelling or dispersing an inorganic layered compound having a different in-plane refractive index and a refractive index in a thickness direction in a solvent, followed by coating and drying. The retardation plate according to claim 1, wherein 3. The retardation plate according to claim 1, wherein the retardation plate contains an optically transparent resin. 4. An inorganic layered compound layer containing an optically transparent resin, wherein an inorganic layered compound having a different in-plane refractive index and a thickness direction refractive index is swollen or dispersed in a solvent, and is optically transparent. The retardation plate according to claim 3, wherein the dispersion is obtained by applying and drying a dispersion obtained by mixing a liquid in which a resin is dissolved. 5. The film according to claim 1, wherein the film is laminated on a film having an in-plane retardation value of 50 nm or less.
The retardation plate according to any one of claims 1 to 4. 6. The retardation plate according to claim 1, wherein the retardation plate is laminated on a birefringent film having a negative refractive index anisotropy. 7. A liquid crystal display device using the retardation plate according to claim 1 as an optical compensator.