JP2002296423A - Optical compensation sheet and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve strength of an optical compensation sheet. SOLUTION: In the optical compensation sheet having an optically anisotropic layer formed out of liquid crystalline molecules and a transparent supporting body, a polyfunctional monomer with four or more double bonds in a molecule is added to the optically anisotropic layer and is polymerized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical compensatory sheet having an optically anisotropic layer formed from liquid crystalline molecules and a transparent support, and a liquid crystal display using the same.

[0002]

2. Description of the Related Art A liquid crystal display device comprises a liquid crystal cell and a polarizing plate. In a transmission type liquid crystal display device, two polarizing plates are attached to both sides of a liquid crystal cell. In a reflection type liquid crystal display device, a reflection plate, a liquid crystal cell, and one polarizing plate are arranged in this order.
The liquid crystal cell includes rod-like liquid crystal molecules, two substrates for enclosing the same, and an electrode layer for applying a voltage to the rod-like liquid crystal molecules. In the liquid crystal cell, the alignment state of the rod-like liquid crystal molecules is different.
c), IPS (In-Plane Switching), FLC (Ferroel
ectric Liquid Crystal), OCB (Optically Compens)
atory Bend), STN (Supper Twisted Nematic), V
A (Vertically Aligned), for reflection type, HAN
Various display modes such as (Hybrid Aligned Nematic) and TN have been proposed.

An ordinary liquid crystal display device uses an optical compensation sheet (retardation plate) in addition to a liquid crystal cell and a polarizing plate. The optical compensation sheet is used to eliminate coloring of an image or to enlarge a viewing angle. In a transmission type liquid crystal display device, one or two optical compensation sheets are arranged between a liquid crystal cell and a polarizing plate. In a reflection type liquid crystal display device, one optical compensation sheet is disposed between a liquid crystal cell and a polarizing plate. As the optical compensation sheet, a stretched birefringent film has been conventionally used. Recently, instead of an optical compensatory sheet made of a stretched birefringent film, an optical compensatory sheet having an optically anisotropic layer formed of liquid crystal molecules (particularly discotic liquid crystal molecules) on a transparent support is used. Has been proposed. The optically anisotropic layer is formed by aligning liquid crystal molecules and fixing the alignment state.
Liquid crystal molecules have a large birefringence. The liquid crystal molecules have various alignment forms. By using liquid crystal molecules, it has become possible to realize optical properties that cannot be obtained with a conventional stretched birefringent film.

[0004] The optical properties of the optical compensatory sheet are determined according to the optical properties of the liquid crystal cell, specifically, the difference in the display mode as described above. When liquid crystal molecules, particularly discotic liquid crystal molecules, are used, it is possible to manufacture an optical compensation sheet corresponding to various display modes of a liquid crystal cell (which can optically compensate). As optical compensation sheets using discotic liquid crystal molecules, those corresponding to various display modes have already been proposed. For example, an optical compensation sheet for a TN mode liquid crystal cell is disclosed in JP-A-6-214116,
These are described in U.S. Pat. Nos. 5,583,679 and 5,646,703 and German Patent Publication 391,620 A1. An optical compensatory sheet for a liquid crystal cell of the IPS mode or the FLC mode is described in JP-A-10-54982. Further, an optical compensatory sheet for an OCB mode or HAN mode liquid crystal cell is disclosed in US Pat.
No. 3 and International Patent Application WO 96/37804. Further, an optical compensation sheet for a liquid crystal cell in the STN mode is described in JP-A-9-26572. An optical compensatory sheet for a VA mode liquid crystal cell is described in Japanese Patent No. 2866372.

In the manufacture of a liquid crystal display device, components such as a liquid crystal cell, a polarizing plate and an optical compensation sheet are sequentially attached with an adhesive. The liquid crystal cell, the polarizing plate, and the optical compensatory sheet need to strictly adjust their optical directions (polarization axis and slow axis) in accordance with the display mode of the liquid crystal cell. For this reason, it is inevitable that some defective products have a sticking direction out of the standard. It is desirable that those defective products be peeled off and reused. However, when trying to remove the optical compensation sheet from the liquid crystal cell,
There has been a problem that the optical compensation sheet is broken and cannot be reused. In order to reuse the liquid crystal cell to which a part of the optical compensation sheet has adhered, a cleaning operation for removing the part of the attached optical compensation sheet is necessary.

Therefore, there is a demand for a means for improving the strength without adversely affecting the optical function of the optical compensation sheet. JP-A-8-27284 discloses a method of introducing a polymerizable group into discotic liquid crystal molecules, orienting the discotic liquid crystal molecules, and then polymerizing the molecules to obtain an optical compensation sheet having high strength. Have been.
JP-A-9-152509 discloses that in addition to discotic liquid crystal molecules, a polymerizable group is introduced into a polymer of an alignment film provided between a transparent support and an optically anisotropic layer,
A method for copolymerizing a polymer and discotic liquid crystalline molecules is disclosed. JP-A-2000-235117
Japanese Patent Application Laid-Open Publication No. H11-163,086 discloses an optical compensatory sheet in which a transparent support and an optically anisotropic layer are bonded at a strength such that the peel strength is 400 g / cm or more. As a means for enhancing the peel strength, a method of adding inorganic fine particles to a transparent support, an alignment film or an optically anisotropic layer is disclosed.

[0007]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 8-27284
No. 9-152509 and JP-A-2000-235
By adopting the means described in each of the publications, the optical compensatory sheet having excellent strength can be obtained. But,
The present inventor further studied and found that even when the optical compensatory sheet was peeled off from the liquid crystal cell and reused, the liquid crystal cell was removed several times or once every several tens of times even if the improved means of the conventional technology was adopted. The problem that a part of the optical compensation sheet adhered to the substrate was observed. Therefore, in order to peel off and reuse the optical compensation sheet from the liquid crystal cell, it is necessary to further improve the strength of the optical compensation sheet. An object of the present invention is to provide an optical compensatory sheet having further improved strength. Another object of the present invention is to provide an optical compensatory sheet capable of reusing components even if a defective product occurs in a bonding step in manufacturing a liquid crystal display device.

[0008]

The object of the present invention has been attained by the following optical compensation sheets and (1) to (11). (1) An optical compensation sheet having an optically anisotropic layer formed from liquid crystal molecules and a transparent support, wherein the optically anisotropic layer further has a polyfunctional monomer having four or more double bonds in the molecule. An optical compensatory sheet comprising a polymer of

(2) The optical compensation sheet according to (1), wherein the polyfunctional monomer is an ester of acrylic acid or methacrylic acid with a polyol having four or more hydroxyls in the molecule. (3) The optical compensation sheet according to (1), wherein the liquid crystal molecules are discotic liquid crystal molecules. (4) the discotic liquid crystal molecule has a double bond,
The optical compensation sheet according to (3), wherein the discotic liquid crystalline molecule and the polyfunctional monomer are copolymerized.

(5) The optical compensation sheet according to (1), wherein an alignment film is provided between the optically anisotropic layer and the transparent support. (6) The optical compensation sheet according to (5), wherein the alignment film comprises a polymer having a double bond in a side chain, and the polymer of the alignment film and a polyfunctional monomer are copolymerized. (7) The optical compensation sheet according to (1), wherein the transparent support has a Re retardation value of 0 to 50 nm and an Rth retardation value of 70 to 400 nm.

(8) When the transparent support is from 59.0 to 61.
The optical compensation sheet according to (1), comprising a cellulose acetate film having a degree of acetylation of 5%. (9) The optical compensation sheet according to (8), wherein the cellulose acetate film contains 0.01 to 20 parts by mass of an aromatic compound having at least two aromatic rings based on 100 parts by mass of cellulose acetate. (10) The optical compensation sheet according to (8), wherein the cellulose acetate film is formed by a co-casting method. (11) A cellulose acetate film was formed from a cellulose acetate solution using a solvent containing ether having 2 to 12 carbon atoms, ketone having 3 to 12 carbon atoms or ester having 2 to 12 carbon atoms as a solvent ( An optical compensation sheet according to 8). (12) A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein at least one optical compensation sheet is disposed between the liquid crystal cell and at least one polarizing plate. The optical compensation sheet has an optically anisotropic layer and a transparent support formed from liquid crystalline molecules, and the transparent support may function as a transparent protective film of the polarizing plate,
A liquid crystal display device, wherein the optically anisotropic layer further contains a polymer of a polyfunctional monomer having four or more double bonds in the molecule.

[0012]

As a result of the study of the present inventors, in order to further improve the strength of the optical compensation sheet, it is necessary to increase the number of double bonds functioning as a polymerizable functional group in the optically anisotropic layer. It has been found. As described in JP-A-8-27284, a method of introducing a polymerizable group into liquid crystal molecules contained in an optically anisotropic layer is very effective for improving strength. However, the number of polymerizable groups that can be introduced into a liquid crystal molecule is limited. It is necessary to determine the molecular structure and the amount of the liquid crystal molecules to be used with priority given to the most important optical properties, and it is not possible to consider only the strength of the optically anisotropic layer. The method of introducing a polymerizable group into the polymer of the alignment film described in JP-A-9-152509 is effective only at the interface between the alignment film and the optically anisotropic layer.
In other words, the strength of the optically anisotropic layer itself cannot be improved. In particular, the optically anisotropic layer is relatively thick (eg, 1.
In the case of the optical compensation sheet (having a thickness of 5 μm or more), it is necessary to improve the strength of the optically anisotropic layer by using another means together. The inorganic fine particles described in JP-A-2000-235117 are also effective for improving the strength of the optical compensation sheet. However, the amount of the inorganic fine particles needs to be adjusted within a range that does not impair the functions of the optically anisotropic layer and the alignment film.

As a result of further research, the present inventors have found that a polyfunctional monomer having four or more double bonds in a molecule is added to an optically anisotropic layer to form a polymer from the monomer. An optical compensation sheet having significantly improved strength was successfully obtained. The polyfunctional monomer can significantly increase the number of double bonds functioning as a polymerizable functional group in the optically anisotropic layer without substantially affecting the optical function of the optically anisotropic layer. By performing the polymerization reaction after significantly increasing the number of double bonds in the optically anisotropic layer, an optical compensatory sheet having significantly improved strength of the optically anisotropic layer was obtained. As a result, even if the optical compensatory sheet of the present invention is adhered to the liquid crystal cell and then peeled off, almost no problem is observed in which a part of the optical compensatory sheet adheres to the substrate of the liquid crystal cell.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Basic Configuration of Liquid Crystal Display] FIG.
FIG. 1 is a schematic diagram showing a basic configuration of a transmission type liquid crystal display device. The transmissive liquid crystal display device shown in FIG. 1 has a transparent protective film (1a) and a polarizing film (2
a), a transparent protective film (3a), a transparent support (4a), an optically anisotropic layer (5a), a lower substrate of a liquid crystal cell (6a), a rod-like liquid crystal molecule (7), and an upper substrate of a liquid crystal cell (6b). ), Optically anisotropic layer (5b), transparent support (4b), transparent protective film (3
b), a polarizing film (2b), and a transparent protective film (1b). The transparent protective films (1a) to (3a) constitute the lower polarizing plate. The transparent support (4a) to the optically anisotropic layer (5a) constitute the lower optical compensation sheet. The optically anisotropic layer (5b) to the transparent support (4b) constitute the upper optical compensation sheet. The transparent protective film (3b) to the transparent protective film (1b) constitute the upper polarizing plate. The lower polarizing plate and the lower optical compensation sheet may be integrated by using a single polymer film as the transparent protective film (3a) and the transparent support (4a). Similarly, the upper optical compensatory sheet and the upper polarizing plate may be integrated by using the transparent support (4b) and the transparent protective film (3b) with one polymer film.

FIG. 2 is a schematic diagram showing another basic configuration of the transmission type liquid crystal display device. The transmission type liquid crystal display device shown in FIG. 2 includes, in order from the backlight (BL) side, a transparent protective film (1a), a polarizing film (2a), a transparent protective film (3a), a transparent support (4), and an optically anisotropic film. Layer (5), liquid crystal cell lower substrate (6a), rod-shaped liquid crystal molecules (7), liquid crystal cell upper substrate (6b), transparent protective film (3b), polarizing film (2b), and transparent protective film (1b). Transparent protective film (1a)
-The transparent protective film (3a) constitutes the lower polarizing plate. The transparent support (4) to the optically anisotropic layer (5) constitute an optical compensation sheet. The transparent protective film (3b) to the transparent protective film (1b) constitute the upper polarizing plate. The lower polarizing plate and the optical compensatory sheet may be integrated by using the transparent protective film (3a) and the transparent support (4) with one polymer film.

FIG. 3 is a schematic diagram showing still another basic configuration of the transmission type liquid crystal display device. The transmission type liquid crystal display device shown in FIG. 3 includes, in order from the backlight (BL) side, a transparent protective film (1a), a polarizing film (2a), and a transparent protective film (3).
a), lower substrate of liquid crystal cell (6a), rod-like liquid crystalline molecules (7), upper substrate of liquid crystal cell (6b), optically anisotropic layer (5), transparent support (4), transparent protective film (3b) ), A polarizing film (2b), and a transparent protective film (1b). The transparent protective films (1a) to (3a) constitute the lower polarizing plate. The optically anisotropic layer (5) to the transparent support (4) constitute an optical compensation sheet. The transparent protective film (3b) to the transparent protective film (1b) constitute the upper polarizing plate. The optical compensatory sheet and the upper polarizing plate may be integrated by using the transparent support (4) and the transparent protective film (3b) as a single polymer film.

FIG. 4 is a schematic diagram showing a basic configuration of a reflection type liquid crystal display device. In the reflection type liquid crystal display device shown in FIG. 4, the lower substrate (6)
a), rod-like liquid crystal molecules (7), upper substrate of liquid crystal cell (6)
b), an optically anisotropic layer (5), a transparent support (4), a transparent protective film (3), a polarizing film (2), and a transparent protective film (1). The optically anisotropic layer (5) to the transparent support (4) constitute an optical compensation sheet. Transparent protective film (3)
-The transparent protective film (1) forms a polarizing plate. The optical compensation sheet and the polarizing plate are composed of a transparent support (4) and a transparent protective film (3).
May be integrated by using a single polymer film.

[Polyfunctional monomer] In the present invention, a polyfunctional monomer having four or more double bonds in the molecule is used. The double bond is preferably an ethylenic (aliphatic) unsaturated double bond. The number of double bonds in the molecule is 4
From 20 to 20, more preferably from 5 to 15, and most preferably from 6 to 10. The polyfunctional monomer is preferably an ester of a polyol having four or more hydroxyls in the molecule and an unsaturated fatty acid. Examples of unsaturated fatty acids include acrylic acid, methacrylic acid, maleic acid and itaconic acid. Acrylic acid and methacrylic acid are preferred. The polyol having four or more hydroxyls in the molecule is preferably a tetrahydric or higher alcohol or an oligomer of a trihydric or higher alcohol. The oligomer has a molecular structure in which polyhydric alcohols are linked by an ether bond, an ester bond or a urethane bond. An oligomer having a molecular structure in which polyhydric alcohols are linked by an ether bond is preferable.

Esters of polyol and (meth) acrylic acid include pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and polyether-based polyol poly (meth) acrylate. ) Acrylates, poly (meth) acrylates of polyester-based polyols, and poly (meth) acrylates of polyurethane-based polyols. A commercial product of a polyfunctional monomer may be used. Monomers composed of an ester of polyol and acrylic acid include Mitsubishi Rayon Co., Ltd. (trade name: Diabeam UK-4154), Toagosei Co., Ltd. (trade name: Aronix M450) and Nippon Kayaku Co., Ltd. (trade name) : KYARAD DPHA, SR355). Two or more polyfunctional monomers may be used in combination.

A polyfunctional monomer having four or more double bonds in a molecule and a monomer having one to three double bonds in a molecule may be used in combination. The combined use of monomers is effective in adjusting the viscosity and strength. That is, as the number of double bonds in the monomer increases, the intermolecular interaction increases, and the viscosity increases. When the viscosity increases, it takes time to align the liquid crystal compound. On the other hand, when the number of double bonds is large, the strength of the optical compensation sheet can be enhanced. Appropriate viscosity and appropriate strength can be easily achieved by using two or more monomers in combination. The polyfunctional monomer having four or more double bonds in the molecule is preferably 20 to 80% by mass, more preferably 30 to 70% by mass of the total amount of the monomer. The polyfunctional monomer is added to the optically anisotropic layer together with the liquid crystal molecules. The addition amount of the polyfunctional monomer is preferably from 0.1 to 50% by mass, more preferably from 1 to 20% by mass, based on the liquid crystal molecules.

[Transparent support] The support is transparent.
It means that the light transmittance is 80% or more. The transparent support preferably has a Re retardation value of 0 to 50 nm and an Rth retardation value of 70 to 400 nm. The Re retardation value and the Rth retardation value are defined by the following formulas (I) and (II), respectively. (I) Re = (nx−ny) × d (II) Rth = {(nx + ny) / 2−nz} × d

In the formulas (I) and (II), nx is
It is the refractive index in the slow axis direction (the direction in which the refractive index is maximized) in the plane of the transparent support. In formulas (I) and (II),
ny is the refractive index in the fast axis direction (the direction in which the refractive index is minimum) in the plane of the transparent support. In the formula (II), nz
Is the refractive index in the thickness direction. In the formulas (I) and (II), d is the thickness of the transparent support in nm.

When two optical compensation sheets are used in a liquid crystal display device, the Rth retardation value of the transparent support is
Preferably it is 70 to 200 nm. When one optical compensation sheet is used for a liquid crystal display device, the Rth retardation value of the transparent support is preferably 150 to 400 nm. The birefringence of the transparent support (Δ
n: nx-ny) is preferably less than 0.002. Further, the birefringence in the thickness direction of the transparent support ｛(nx
+ Ny) / 2-nz} is preferably 0.001 to 0.04.

The transparent support is preferably formed from a polymer film. The polymer forming the polymer film is preferably a cellulose ester, more preferably a cellulose acetate, and even more preferably a cellulose acetate having an acetylation degree of 59.0 to 61.5%. The degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The acetylation degree is ASTM: D-817-9
In accordance with the measurement and calculation of the degree of acetylation in No. 1 (test method for cellulose acetate or the like). The viscosity average degree of polymerization (DP) of the polymer forming the film is preferably 250 or more, more preferably 290 or more. Further, the polymer was obtained by gel permeation chromatography using Mw / Mn (Mw is a mass average molecular weight,
(Mn is a number average molecular weight) preferably has a narrow molecular weight distribution. Specific values of Mw / Mn are 1.0 to 1.
7, more preferably from 1.3 to 1.65, and most preferably from 1.4 to 1.6.

In order to adjust the retardation of the polymer film, an aromatic compound having at least two aromatic rings can be used as a retardation increasing agent. When a cellulose acetate film is used as the polymer film, the aromatic compound is used in an amount of 0.01 to 20 parts by mass based on 100 parts by mass of the cellulose acetate. The aromatic compound is preferably used in a range of 0.05 to 15 parts by mass, more preferably in a range of 0.1 to 10 parts by mass, based on 100 parts by mass of cellulose acetate. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring.

The aromatic hydrocarbon ring is a six-membered ring (ie,
Benzene ring). Aromatic heterocycles are generally unsaturated heterocycles. The aromatic hetero ring is preferably a 5-, 6-, or 7-membered ring, more preferably a 5- or 6-membered ring.
Aromatic heterocycles generally have the most double bonds.
As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of the aromatic hetero ring include a furan ring, a thiophene ring, a pyrrole ring,
Oxazole ring, isoxazole ring, thiazole ring,
Isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,
Includes a 5-triazine ring. As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable, A benzene ring and a 1,3,5-triazine ring are more preferred. It is particularly preferred that the aromatic compound has at least one 1,3,5-triazine ring.

The number of aromatic rings in the aromatic compound is 2
To 20, preferably 2 to 12, more preferably 2 to 8, and most preferably 2 to 6. The bonding relationship between two aromatic rings is as follows: (a) when forming a condensed ring, (b)
It can be classified into a case where a single bond is directly bonded and a case where it is bonded via a (c) linking group (a spiro bond cannot be formed due to an aromatic ring). The connection relationship may be any of (a) to (c).

Examples of the condensed ring (a) (condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring,
It includes a phenanthridine ring, a xanthene ring, a phenazine ring, a phenothiazine ring, a phenoxatiin ring, a phenoxazine ring and a thianthrene ring. A naphthalene ring, an azulene ring, an indole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, a benzotriazole ring and a quinoline ring are preferred. The single bond in (b) is preferably a bond between carbon atoms of two aromatic rings. By joining two aromatic rings with two or more single bonds,
An aliphatic ring or a non-aromatic heterocyclic ring may be formed between two aromatic rings.

The connecting group (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is an alkylene group, alkenylene group, alkynylene group, -CO-, -O
-, -NH-, -S- or a combination thereof is preferred. Examples of the linking group consisting of a combination are shown below. Note that the left and right relationships in the following examples of the linking group may be reversed. c1: -CO-O-c2: -CO-NH-c3: -alkylene-O-c4: -NH-CO-NH-c5: -NH-CO-O-c6: -O-CO-O-c7: -O-alkylene-O-c8: -CO-alkenylene-c9: -CO-alkenylene-NH-c10: -CO-alkenylene-O-c11: -alkylene-CO-O-alkylene-O-CO
-Alkylene-c12: -O-alkylene-CO-O-alkylene-O-
CO-alkylene-O-c13: -O-CO-alkylene-CO-O-c14: -NH-CO-alkenylene- c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent. Examples of the substituent include a halogen atom (F, C
1, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl, alkenyl, alkynyl, aliphatic acyl, aliphatic acyloxy, alkoxy, alkoxycarbonyl , Alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic substituted sulfamoyl group, aliphatic substituted ureido group and non-aromatic Group heterocyclic groups.

The alkyl group preferably has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable.
The alkyl group may further have a substituent (eg, hydroxy, carboxy, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl,
-Hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-diethylaminoethyl. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable.
The alkenyl group may further have a substituent. Examples of the alkenyl group include vinyl, allyl and 1-hexenyl. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl, 1-butynyl and 1-hexynyl.

The number of carbon atoms of the aliphatic acyl group is 1 to 1
It is preferably 0. Examples of the aliphatic acyl group include acetyl, propanoyl and butanoyl. The aliphatic acyloxy group preferably has 1 to 10 carbon atoms. Examples of the aliphatic acyloxy group include acetoxy. The alkoxy group preferably has 1 to 8 carbon atoms. The alkoxy group may further have a substituent (eg, an alkoxy group). Examples of alkoxy groups (including substituted alkoxy groups) include methoxy, ethoxy, butoxy and methoxyethoxy. The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl. The alkoxycarbonylamino group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonylamino group include methoxycarbonylamino and ethoxycarbonylamino.

The number of carbon atoms of the alkylthio group is 1 to 1
It is preferably 2. Examples of the alkylthio group include methylthio, ethylthio and octylthio.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include methanesulfonyl and ethanesulfonyl. The aliphatic amide group preferably has 1 to 10 carbon atoms. Examples of the aliphatic amide group include acetamide. The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamide group include methanesulfonamide, butanesulfonamide and n-octanesulfonamide. The aliphatic substituted amino group preferably has 1 to 10 carbon atoms. Examples of the aliphatic substituted amino group include dimethylamino, diethylamino and 2-carboxyethylamino. The aliphatic substituted carbamoyl group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted carbamoyl group include methylcarbamoyl and diethylcarbamoyl. The aliphatic substituted sulfamoyl group preferably has 1 to 8 carbon atoms. Examples of the aliphatic-substituted sulfamoyl group include methylsulfamoyl and diethylsulfamoyl. The aliphatic substituted ureido group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted ureido group include methyl ureide. Examples of the non-aromatic heterocyclic group include piperidino and morpholino. The molecular weight of the retardation increasing agent is preferably from 300 to 800. For compound examples of retardation increasing agents,
JP-A-2000-11114, 2000-2754
No. 34 and WO00 / 65384.

It is preferable to produce the polymer film by a solvent casting method. In the solvent casting method, a film is manufactured using a solution (dope) in which a polymer is dissolved in an organic solvent. The organic solvent is a solvent selected from ethers having 3 to 12 carbon atoms, ketones having 3 to 12 carbon atoms, esters having 3 to 12 carbon atoms, and halogenated hydrocarbons having 1 to 6 carbon atoms. It is preferable to include Ethers, ketones and esters may have a cyclic structure. Compounds having two or more functional groups of ether, ketone and ester (that is, -O-, -CO- and -COO-) can also be used as the organic solvent. The organic solvent is
It may have another functional group such as an alcoholic hydroxyl group. In the case of an organic solvent having two or more types of functional groups, the number of carbon atoms may be within the range specified for the compound having any one of the functional groups.

Examples of the ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolan, tetrahydrofuran, anisole and phenetole. Examples of the ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexanone. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of the organic solvent having two or more functional groups include:
Includes 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol. The number of carbon atoms in the halogenated hydrocarbon is preferably 1 or 2, and most preferably 1. The halogen of the halogenated hydrocarbon is preferably chlorine. The proportion of halogenated hydrocarbons in which hydrogen atoms are replaced by halogens is preferably 25 to 75 mol%, and preferably 3 to 75 mol%.
The content is more preferably 0 to 70 mol%, further preferably 35 to 65 mol%, and more preferably 40 to 60 mol%.
Most preferably, it is mol%. Methylene chloride is a typical halogenated hydrocarbon. Two or more organic solvents may be used as a mixture.

The polymer solution can be prepared by a general method. The general method means that the treatment is performed at a temperature of 0 ° C. or higher (normal temperature or high temperature). The solution can be prepared using a dope preparation method and apparatus in a usual solvent casting method. In the case of a general method, it is preferable to use a halogenated hydrocarbon (particularly, methylene chloride) as the organic solvent. The amount of the polymer is adjusted so that the obtained solution contains 10 to 40% by mass. More preferably, the amount of polymer is from 10 to 30% by weight. In the organic solvent (main solvent), any additives described below may be added.
The solution can be prepared by stirring the polymer and the organic solvent at room temperature (0 to 40 ° C.). The highly concentrated solution may be stirred under pressure and heating conditions. Specifically, the polymer and the organic solvent are sealed in a pressurized container, and the mixture is stirred while being heated under pressure to a temperature not lower than the boiling point of the solvent at normal temperature and in a range where the solvent does not boil. The heating temperature is usually 40 ° C. or higher, preferably 60 to 2
It is 00 ° C, more preferably 80 to 110 ° C.

The components may be roughly mixed in advance and then placed in a container. Moreover, you may put in a container sequentially. The container must be configured to be able to stir. The container can be pressurized by injecting an inert gas such as nitrogen gas. Further, an increase in the vapor pressure of the solvent due to heating may be used.
Alternatively, each component may be added under pressure after the container is sealed. When heating, it is preferable to heat from outside the container. For example, a jacket-type heating device can be used. Further, a plate heater may be provided outside the container, and the entire container may be heated by circulating the liquid through piping. It is preferable to provide a stirring blade inside the container and stir using the stirring blade. The stirring blade preferably has a length reaching the vicinity of the container wall. It is preferable to provide a scraping blade at the end of the stirring blade to renew the liquid film on the wall of the container. Instruments such as a pressure gauge and a thermometer may be installed in the container. Dissolve each component in the solvent in the container.
The prepared dope is taken out of the container after cooling, or is taken out and then cooled using a heat exchanger or the like.

A solution can be prepared by a cooling dissolution method. In the cooling dissolution method, the polymer can be dissolved even in an organic solvent that is difficult to dissolve by a normal dissolution method. In addition, even if it is a solvent which can dissolve a polymer by a usual dissolution method, according to a cooling dissolution method, there is an effect that a uniform solution can be obtained quickly. In the cooling dissolution method, first, a polymer is gradually added to an organic solvent at room temperature with stirring. The amount of polymer is between 10 and 4 in this mixture.
It is preferable to adjust so as to contain 0% by mass. More preferably, the amount of polymer is from 10 to 30% by weight. Further, an optional additive described below may be added to the mixture.

Next, the mixture is heated to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -10 ° C).
To -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). Upon such cooling, the mixture of polymer and organic solvent solidifies. The cooling rate is preferably 4 ° C./min or more, and 8 ° C./min.
Minutes or more, and most preferably 12 ° C./minute or more. The cooling rate is preferably as high as possible, but the theoretical upper limit is 10,000 ° C./sec.
0 ° C./sec is a technical upper limit, and 100 ° C./sec is a practical upper limit. The cooling rate is a value obtained by dividing the difference between the temperature at which the cooling is started and the final cooling temperature by the time from when the cooling is started until the temperature reaches the final cooling temperature.

Further, this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C.,
When heated to the temperature (most preferably 0 to 50 ° C.), the polymer dissolves in the organic solvent. The temperature may be raised only by leaving it at room temperature or may be heated in a warm bath. Heating rate is 4
C./min or higher is preferable, 8 C / min or higher is more preferable, and 12 C / min or higher is most preferable. The heating rate is preferably as fast as possible.
00 ° C / sec is the theoretical upper limit, 1000 ° C / sec is the technical upper limit, and 100 ° C / sec is the practical upper limit. Note that the heating rate is a value obtained by dividing the difference between the temperature at which heating is started and the final heating temperature by the time from when heating is started to when the final heating temperature is reached. . As described above, a uniform solution is obtained. If the dissolution is insufficient, the operation of cooling and heating may be repeated.
Whether or not the dissolution is sufficient can be determined only by visually observing the appearance of the solution.

In the cooling dissolution method, it is desirable to use a closed container in order to avoid water contamination due to condensation during cooling. Also, in the cooling and heating operation, pressurization during cooling,
By reducing the pressure during the heating, the dissolution time can be shortened. In order to perform pressurization and decompression, it is desirable to use a pressure-resistant container. According to differential scanning calorimetry (DSC), a 20% by mass solution of cellulose acetate (degree of acetylation: 60.9%, viscosity average degree of polymerization: 299) dissolved in methyl acetate by a cooling dissolution method was 3%.
A pseudo phase transition point between the sol state and the gel state exists at around 3 ° C., and below this temperature, the gel state becomes uniform. Therefore,
This solution must be stored at a temperature equal to or higher than the quasi phase transition temperature, preferably at a temperature of about 10 ° C. plus the gel phase transition temperature. However, this pseudo phase transition temperature differs depending on the acetylation degree of cellulose acetate, the viscosity average polymerization degree, the solution concentration and the organic solvent used.

From the prepared polymer solution (dope), a polymer film is produced by a solvent casting method. It is preferable to add the above-mentioned retardation increasing agent to the dope. The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%. It is preferable that the surface of the drum or the band is finished in a mirror state. The casting and drying methods in the solvent casting method are described in US Pat. Nos. 2,336,310 and 2,367,603.
Nos. 2492078, 2492977, 24
No. 92978, No. 2607704, No. 2739069
Nos. 2739070, British Patent Nos. 640731 and 736892, Japanese Patent Publication No. 45-4554,
JP-A-49-5614, JP-A-60-176834, JP-A-60-203430, and JP-A-62-115035. The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry by blowing on air for 2 seconds or more. The obtained film can be peeled off from the drum or band, and further dried with hot air having a temperature gradually changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in JP-B-5-17844. According to this method, the time from casting to stripping can be reduced. In order to carry out this method, it is necessary that the dope gels at the surface temperature of the drum or band during casting.

Using the prepared polymer solution (dope), two or more layers can be simultaneously cast (co-cast) to form a film. The dope before co-casting has a solid content of 10
It is preferable to adjust the concentration so as to be 50 to 50%. When co-casting a plurality of cellulose acetate solutions, it is possible to prepare a film while casting and laminating a solution containing cellulose acetate from a plurality of casting ports provided at intervals in the traveling direction of the support, respectively. it can. About co-casting, JP-A-61-158414,
These are described in JP-A-1-122419 and JP-A-11-198285. Alternatively, a film may be produced by casting a cellulose acetate solution from two casting ports (Japanese Patent Publication No. 60-27662, Japanese Patent Application Laid-Open No. 61-61, 1987).
No. 94724, No. 61-947245, No. 61-10
Nos. 4813 and 61-158413, JP-A-6-13
No. 4933). A method for casting a cellulose acetate film in which a flow of a high-viscosity cellulose acetate solution is wrapped with a low-viscosity cellulose acetate solution and the high- and low-viscosity cellulose acetate solutions are simultaneously extruded (described in JP-A-56-162617). Can also be applied. Further, using two casting ports, the film formed on the support by the first casting port is peeled off, and the second casting is performed on the side in contact with the surface of the support to produce a film (particularly, Japanese Patent Publication No. 44-20235). A plurality of dopes co-cast may have the same composition. In addition to the polymer film used as the transparent support, other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, an ultraviolet absorbing layer, and a polarizing layer) can be simultaneously cast.

In the case of single-layer casting, it is necessary to extrude a high-concentration, high-viscosity dope in order to obtain a constant film thickness. For this reason, the stability of the dope is poor, and solid matter is generated, which may cause a bump failure or a problem of poor flatness. When a plurality of dopes are co-cast from a plurality of casting ports, a high-viscosity solution can be simultaneously extruded onto a support. As a result, an excellent planar film having good flatness can be produced. Further, by using a thick dope, drying addition is reduced, and the film production speed is increased.

A plasticizer can be added to the polymer film in order to improve the mechanical properties or to increase the drying speed. As the plasticizer, a phosphoric acid ester or a carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP)
And tricresyl phosphate (TCP). Representative carboxylic esters include phthalic esters and citric esters. Examples of phthalate esters include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DB
P), dioctyl phthalate (DOP), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include:
Includes O-acetyl triethyl citrate (OACTE) and O-acetyl tributyl citrate (OACTB). Examples of other carboxylic esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic esters. Phthalate ester plasticizers (DMP, DEP, DBP, D
OP, DPP, DEHP) are preferably used. DE
P and DPP are particularly preferred. The amount of the plasticizer added is preferably 0.1 to 25% by mass of the amount of the polymer, more preferably 1 to 20% by mass, and more preferably 3 to 20% by mass.
Most preferably, it is from 15 to 15 mass%.

In the polymer film, a deterioration inhibitor (eg,
Antioxidants, peroxide decomposers, radical inhibitors, metal deactivators, acid scavengers, amines). Regarding the deterioration inhibitor, JP-A-3-199201, JP-A-3-199201.
1907073, 5-194789, 5-27
Nos. 1471 and 6-107854. The amount of the deterioration inhibitor added is preferably 0.01 to 1% by mass of the solution (dope) to be prepared.
More preferably, it is from 0.2 to 0.2% by mass. When the addition amount is less than 0.01% by mass, the effect of the deterioration inhibitor is hardly recognized. If the amount exceeds 1% by mass, bleed-out (bleeding out) of the deterioration inhibitor on the film surface may be observed. Examples of particularly preferred deterioration inhibitors include butylated hydroxytoluene (BH
T) and tribenzylamine (TBA).

In order to improve the thermal conductivity of the transparent support,
Various high thermal conductivity particles can be added to the polymer film. The high thermal conductive fine particles are preferably formed from a transparent material. Examples of specific materials include aluminum nitride, silicon nitride, boron nitride, magnesium nitride, silicon carbide, aluminum oxide, silicon oxide, zinc oxide, magnesium oxide, and carbon (including diamond).
And metals. The average particle size of the high thermal conductive particles is
The thickness is preferably 0.05 to 80 μm, and more preferably 0.1 to 10 μm. The high thermal conductive particles are preferably used in a range of 5 to 100 parts by mass, more preferably 5 to 50 parts by mass, based on 100 parts by mass of the polymer.

The polymer film is preferably stretched in order to reduce the hygroscopic expansion (decrease the coefficient of hygroscopic expansion). When the moisture absorption expansion is reduced by stretching, it is desirable to uniformly prevent distortion in all directions in the plane. For that purpose, it is preferable to carry out a biaxial stretching treatment. The biaxial stretching includes a simultaneous biaxial stretching method and a sequential biaxial stretching method. From the viewpoint of continuous production, a sequential biaxial stretching method is preferable. In the sequential biaxial stretching method, after casting a dope, the polymer film is peeled off from a band or a drum, stretched in a width direction (a direction perpendicular to the casting direction), and then stretched in a longitudinal direction. The order in which the stretching is performed twice in the width direction and the longitudinal direction may be reversed. Regarding stretching in the width direction, JP-A-62-115035, JP-A-4-152125,
There are descriptions in JP-A Nos. 4-284221, 4-298310 and 11-48271. The stretching of the film is performed at normal temperature or under heating conditions. The heating temperature is preferably equal to or lower than the glass transition temperature of the film. The film can be stretched during a drying process during production. It is preferable to stretch the film while the solvent remains in the film. In the case of stretching in the longitudinal direction, the film is stretched, for example, by adjusting the speed of the film transport roller so that the film winding speed is faster than the film peeling speed. In the case of stretching in the width direction, the film can be stretched by being conveyed while holding the width of the film with a tenter and gradually increasing the width of the tenter. After drying the film, the film can be stretched using a stretching machine (preferably, uniaxial stretching using a long stretching machine). The stretching ratio of the film (the ratio of the increase by stretching to the original length) is preferably 5 to 50%, more preferably 10 to 50%.
-40%, most preferably 15-35%.

The steps from casting to drying may be performed in an atmosphere of a relatively inert gas (eg, nitrogen gas). A commonly used device can be used as the polymer film winding machine. As a winding method, a constant tension method, a constant torque method, a taper tension method, or a program tension control method with constant internal stress can be adopted. By performing the biaxial stretching as described above, the coefficient of hygroscopic expansion of the film can be reduced. The hygroscopic expansion coefficient is the amount of change in the length of the sample when the relative humidity is changed at a constant temperature. In order to prevent the frame-shaped transmittance from increasing, the coefficient of hygroscopic expansion of the cellulose acetate film is preferably 30 × 10 ⁻⁵ /% RH or less, and more preferably 15 × 10 ⁻⁵ /% RH or less. It is most preferably at most 10 × 10 ⁻⁵ /% RH. The smaller the coefficient of hygroscopic expansion is, the more preferable it is, but usually it is 1.0 × 10 ⁻⁵ /% RH or more.

In terms of the coefficient of hygroscopic expansion, first, the width of the prepared polymer film was 5 mm. A sample having a length of 20 mm is cut out, one end is fixed, and the sample is hung in an atmosphere of 25 ° C. and 20% RH (R ₀ ). A 0.5 g weight is hung on the other end and left for 10 minutes to measure the length (L ₀ ). Next, while keeping the temperature at 25 ° C., the humidity is set to 80% RH (R ₁ ), and the length (L ₁ ) is measured. The coefficient of hygroscopic expansion is calculated by the following equation. The measurement is performed for 10 samples of the same sample, and the average value is adopted. Hygroscopic expansion coefficient [/% RH] = {(L ₁ −L ₀ ) / L ₀ }
/ (R ₁ -R ₀ )

The dimensional change due to the moisture absorption may be achieved by reducing the free volume in the polymer film. What largely affects the free volume is the amount of residual solvent at the time of film formation, and the smaller the amount, the smaller the dimensional change. A common approach to reduce residual solvent is to dry at high temperature and for a long time. However,
Drying too long naturally reduces productivity. Therefore, the amount of the residual solvent in the polymer film is 0.1.
It is preferably in the range of 01 to 1% by mass, and 0.0
It is more preferably in the range of 2 to 0.07% by mass, and most preferably in the range of 0.03 to 0.05% by mass. By controlling the amount of the residual solvent, a polymer film can be produced at low cost and with high productivity.

Further, as another method for reducing the dimensional change due to moisture absorption, it is preferable to add a compound having a hydrophobic group. As the hydrophobic group, an alkyl group and phenyl are preferable. The compound to be used is preferably selected from plasticizers and deterioration inhibitors that can be added to the polymer film. Specific compound examples include triphenyl phosphate (TPP) and tribenzylamine (TB
A) is included. The addition amount of the compound having a hydrophobic group is
It is preferably in the range of 0.01 to 10% by mass of the polymer solution (dope), more preferably in the range of 0.1 to 5% by mass, and most preferably in the range of 1 to 3% by mass. .

The polymer film is preferably subjected to a surface treatment. The surface treatment includes corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment, and ultraviolet irradiation treatment. An undercoat layer (described in JP-A-7-333433) may be provided instead of or in addition to the surface treatment. The surface energy of the film after the surface treatment is preferably 55 mN / m or more, more preferably 60 mN / m or more and 75 mN / m or less. From the viewpoint of maintaining the flatness of the film,
Preferably, the temperature of the polymer film in the surface treatment is equal to or lower than Tg (glass transition temperature) of the polymer,
Specifically, the temperature is preferably set to 150 ° C. or lower. When the polymer film is a cellulose acetate film, the surface treatment is preferably an acid treatment or an alkali treatment, that is, a saponification treatment for the cellulose acetate, and more preferably an alkali saponification treatment.

The alkali saponification treatment can be performed by immersing the film surface in an alkaline solution, washing with water, and drying. It may be neutralized with an acidic solution before washing with water. Examples of the alkaline solution include a potassium hydroxide solution and a sodium hydroxide solution, and the specified concentration of hydroxide ions is preferably in the range of 0.1 to 3.0 N,
More preferably, it is in the range of 0.5 to 2.0N. The temperature of the alkaline solution is preferably in the range of room temperature to 90 ° C, more preferably in the range of 40 to 70 ° C. In order to efficiently carry out the alkali saponification treatment, it is also preferable to carry out a saponification treatment in which an alkali solution is applied to the cellulose acetate film. After the saponification treatment, it is preferable to remove the alkali from the film surface by washing with water. In the case of the saponification treatment by coating, it is preferable that the alkali liquid has good wettability to the cellulose acetate film. The wettability of the coating liquid is mainly determined by the type of the solvent. As a solvent having good wettability, alcohol (eg, isopropyl alcohol, n-butanol, methanol, ethanol) is typical.
It is preferable to further add water or glycol (eg, propylene glycol, ethylene glycol) as an auxiliary solvent. The surface energy of a solid is described in "Basics and Applications of Wetting" (Realize, Inc., issued on Dec. 10, 1989).
And the contact angle method, the heat of wetting method, and the adsorption method. In the case of a cellulose acetate film, it is preferable to use a contact angle method. Specifically, two types of solutions whose surface energies are known are dropped on a cellulose acetate film, and at the intersection between the surface of the droplet and the film surface, the angle between the tangent drawn to the droplet and the film surface is determined. The angle containing the drop is defined as the contact angle, and the surface energy of the film can be calculated by calculation.

[Alignment Film] The alignment film has a function of defining the alignment direction of the liquid crystal molecules. The alignment film is formed by rubbing an organic compound (preferably a polymer), obliquely depositing an inorganic compound, forming a layer having microgrooves, or an organic compound (eg, ω-trichosanoic acid) by the Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). In addition, the application of an electric field,
There is also known an alignment film in which an alignment function is generated by applying a magnetic field or irradiating light.

The alignment film is preferably formed by rubbing a polymer. The polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules in principle. In the present invention, in addition to the function of aligning liquid crystal molecules, a cross-linking agent having a function of bonding a side chain having a crosslinkable functional group (eg, a double bond) to the main chain or having a function of aligning liquid crystal molecules. It is preferable to introduce a functional group into the side chain. As the main chain of the alignment film polymer, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid,
Polyacrylic acid ester, polymethacrylic acid ester (eg, polymethyl methacrylate), polyacrylamide (eg, poly (N-methylolacrylamide)), polymethacrylamide, polyolefin (eg, polystyrene, polyvinyl toluene, polyethylene, polypropylene), chlorine Polyolefin (eg, chlorosulfonated polyethylene, polyvinyl chloride), cellulose ester (eg, cellulose nitrate), polyester (eg, polycarbonate), polyimide, polyamide (eg, polyamic acid), polyvinyl ester (eg, polyvinyl acetate) ) Or cellulose ether (eg, carboxymethylcellulose). Copolymers composed of two or more types of repeating units (eg, acrylic acid / methacrylic acid copolymer, styrene / maleimide copolymer, styrene / vinyltoluene copolymer, vinyl acetate /
(Vinyl chloride copolymer, ethylene / vinyl acetate copolymer)
May be used. In addition, a reaction product of a silane coupling agent can also be used as an alignment film polymer.

The main chain of the alignment film polymer is poly (N
-Methylolacrylamide), carboxymethylcellulose, polyvinyl alcohol, polyacrylic acid, polymethacrylic acid, polyimide and polyamide are preferred, with polyvinyl alcohol being particularly preferred. The degree of saponification of polyvinyl alcohol is preferably from 70 to 100%, more preferably from 80 to 100%, and most preferably from 85 to 95%. The polymerization degree of polyvinyl alcohol is preferably from 100 to 3000. A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of the functional group is determined according to the type of the liquid crystal molecule and the required alignment state.

When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or when a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystal molecules,
The polymer of the alignment film and the polyfunctional monomer contained in the optically anisotropic layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer, and between the polyfunctional monomer and the alignment film polymer are firmly bonded by covalent bonds. Therefore, by introducing a crosslinkable functional group into the polymer of the alignment film, the strength of the optical compensation sheet can be significantly improved. The crosslinkable functional group of the alignment film polymer preferably contains a double bond, similarly to the polyfunctional monomer. Hereinafter, examples of the crosslinkable functional group containing a double bond will be described.

[0059]

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The crosslinkable functional group may be directly bonded to the main chain of the polymer of the alignment film, or may be bonded via a linking group. The linking group is an alkylene group, an arylene group, -CO-, -NH
It is preferably a divalent linking group selected from the group consisting of-, -O-, -S- and a combination thereof. The alkylene group preferably has 1 to 12 carbon atoms. The arylene group is preferably phenylene.

The alignment film polymer (particularly, a polymer having polyvinyl alcohol as a main chain) can be crosslinked by using a crosslinking agent separately from the above-mentioned crosslinkable functional group. As the crosslinking agent, aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazoles, and dialdehyde starch can be used. Examples of aldehydes include formaldehyde, glyoxal and glutaraldehyde. Examples of N-methylol compounds include dimethylol urea and methylol dimethylhydantoin. Examples of the dioxane derivative include 2,3-dihydroxydioxane. Examples of compounds that act by activating the carboxyl group include carbenium, 2-naphthalenesulfonate, 1,1-bispyrrolidino-1-chloropyridinium and 1-morpholinocarbonyl-3-
(Sulfonatoaminomethyl). Examples of active vinyl compounds include 1,3,5-triacroyl-hexahydro-s-triazine, bis (vinylsulfone) methane and N, N'-methylenebis- [β- (vinylsulfonyl) propionamide]. Examples of active halogen compounds include 2,4-dichloro-6-hydroxy-S
-Contains triazines. Aldehydes are preferred, and glutaraldehyde is particularly preferred. Two or more crosslinking agents may be used in combination.

The amount of the crosslinking agent added is preferably in the range of 0.1 to 20% by mass of the polymer, and
More preferably, it is in the range of 5% by mass. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, more preferably 0.5% by mass or less of the alignment film. In forming the alignment film, a coating solution containing an alignment film polymer is applied on a transparent support. As a solvent for the coating liquid, an organic solvent (eg, methanol) or a mixed solvent of water and an organic solvent is preferable. Application methods include spin coating, dip coating, curtain coating, extrusion coating,
A bar coating method or an E-type coating method can be employed.
An E-type coating method is particularly preferred. The drying temperature of the coating film is 20
To 110 ° C, preferably 60 to 100 ° C
Is more preferable, and the temperature is most preferably in the range of 80 to 100 ° C. Drying time is from 1 minute to 36
The time is preferably, and more preferably, 5 to 30 minutes.

The rubbing treatment can be performed by a known method. That is, the alignment function is obtained by rubbing the surface of the alignment film in a certain direction using paper, cloth (gauze, felt, nylon, polyester fiber) or rubber. Generally, rubbing is performed several times using a cloth in which fibers having a uniform length and thickness are planted on average. Next, the alignment film functions to align the liquid crystal molecules of the optically anisotropic layer provided on the alignment film. Thereafter, if necessary, the polymer of the alignment film is reacted with the polyfunctional monomer contained in the optically anisotropic layer, or the polymer of the alignment film is cross-linked using a cross-linking agent. The thickness of the alignment film is 0.1 to 10 μm
Is preferably within the range.

[Optical Anisotropic Layer] The optically anisotropic layer is formed from liquid crystalline molecules. As the liquid crystal molecules, rod-shaped liquid crystal molecules or discotic liquid crystal molecules are preferably used. As rod-like liquid crystal molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes,
Cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitrile are preferably used. The rod-like liquid crystal molecules also include metal complexes. Regarding rod-like liquid crystal molecules, see Quarterly Review of Chemistry, Vol. 22, Liquid Crystal Chemistry (1994), edited by The Chemical Society of Japan.
Chapter 7, Chapters 7 and 11, and Chapter 3 of the Liquid Crystal Device Handbook, 142nd Committee of the Japan Society for the Promotion of Science. Discotic liquid crystalline molecules are also described in various references (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vo
l. 71, page 111 (1981); edited by The Chemical Society of Japan, quarterly chemistry review, no. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10, Section 2
(1994); B. Kohne et al., Angew. Chem. Soc. Chem. C
omm., page 1794 (1985); J. Zhang et al., J. Am. Che
m. Soc., vol. 116, page 2655 (1994)).

The liquid crystal molecule preferably has a double bond as a polymerizable functional group. When a double bond is introduced as a polymerizable functional group into a liquid crystal molecule, the polyfunctional monomer contained in the optically anisotropic layer and the liquid crystal molecule can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the liquid crystal molecule and the liquid crystal molecule, and between the polyfunctional monomer and the liquid crystal molecule are firmly bonded by covalent bonds. Therefore, the strength of the optical compensation sheet can be significantly improved by introducing a crosslinkable functional group into the liquid crystal molecules.

In a discotic liquid crystal molecule, if a polymerizable functional group is directly connected to the discotic core, it becomes difficult to maintain an alignment state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable functional group. Therefore,
Discotic liquid crystal molecules having a polymerizable functional group,
The compound represented by the following formula (I) is preferable.

(I) D (-LQ) _{n In} formula (I), D is a discotic core; L is a divalent linking group; Q is a polymerizable functional group; And n is an integer of 4 to 12. Disc core (D)
Is shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

[0068]

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[0069]

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[0070]

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[0071]

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[0072]

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[0073]

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[0074]

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In the formula (I), the divalent linking group (L)
Is an alkylene group, alkenylene group, arylene group,-
It is preferably a divalent linking group selected from the group consisting of CO-, -NH-, -O-, -S- and a combination thereof. The divalent linking group (L) is an alkylene group, an arylene group, -CO-, -NH-, -O- and -S-
The divalent linking group is more preferably a combination of at least two divalent groups selected from the group consisting of The divalent linking group (L) is an alkylene group, an arylene group,-
Most preferably, it is a divalent linking group obtained by combining at least two divalent groups selected from the group consisting of CO- and -O-. The alkylene group has 1 to 1 carbon atoms.
It is preferably 2. The alkenylene group preferably has 2 to 12 carbon atoms. The arylene group preferably has 6 to 10 carbon atoms.

Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is a polymerizable group (Q)
To join. AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. Note that the alkylene group, alkenylene group, and arylene group may have a substituent (eg, an alkyl group). L1: -AL-CO-O-AL- L2: -AL-CO-O-AL-O- L3: -AL-CO-O-AL-O-AL- L4: -AL-CO-O-AL- O-CO-L5: -CO-AR-O-AL-L6: -CO-AR-O-AL-O-L7: -CO-AR-O-AL-O-CO-L8: -CO-NH- AL-L9: -NH-AL-O-L10: -NH-AL-O-CO-

L11: -O-AL- L12: -O-AL-O- L13: -O-AL-O-CO- L14: -O-AL-O-CO-NH-AL- L15: -O- AL-S-AL-L16: -O-CO-AR-O-AL-CO-L17: -O-CO-AR-O-AL-O-CO-L18: -O-CO-AR-O-AL -O-AL-OC
O-L19: -O-CO-AR-O-AL-O-AL-OA
L-O-CO-L20: -S-AL-L21: -S-AL-O-L22: -S-AL-O-CO-L23: -S-AL-S-AL-L24: -S-AR -AL-

Examples of the polymerizable functional group (Q) of the formula (I) are those of the polymerizable functional group (Q1
To Q6). In the formula (I), n is an integer of 4 to 12. Specific figures are disc-shaped cores (D)
Is determined according to the type of The combination of a plurality of L and Q may be different, but is preferably the same.

The optically anisotropic layer can be formed by applying a coating solution containing liquid crystal molecules and, if necessary, a polymerizable initiator and optional components on the alignment film. The thickness of the optically anisotropic layer is preferably 0.5 to 100 μm,
More preferably, it is 0.5 to 30 μm.

After forming the optically anisotropic layer, the polyfunctional monomer is polymerized. When the alignment film polymer or the liquid crystal molecule has a polymerizable group, it is copolymerized with a polyfunctional monomer.
The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. Photopolymerization reactions are preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in U.S. Pat. Nos. 2,367,661 and 2,367,670) and acyloin ethers (U.S. Pat.
No. 48828), α-hydrocarbon-substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (US Pat.
No. 2,951,758), a combination of a triarylimidazole dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), an acridine and phenazine compound (JP-A-60-105).
667, US Pat. No. 4,239,850)
And oxadiazole compounds (US Pat.
0 specification). The amount of the photopolymerization initiator used is preferably from 0.01 to 20% by mass, more preferably from 0.5 to 5% by mass of the solid content of the coating solution. It is preferable to use ultraviolet rays for light irradiation for polymerization. Irradiation energy is 20-5000mJ
/ Cm ² , preferably 100 to 800 mJ
/ Cm ² is more preferable. Light irradiation may be performed under heating conditions to promote the photopolymerization reaction. A protective layer may be provided on the optically anisotropic layer.

[Polarizing Plate] The polarizing plate comprises a polarizing film and two transparent protective films disposed on both sides thereof. Generally, a cellulose acetate film is used as the transparent protective film. As described above, the transparent support of the optical compensation sheet can be used as one protective film. in this case,
The optical compensation sheet and the polarizing plate are integrated (usually function as an elliptically polarizing plate). In the integrated elliptically polarizing plate, the slow axis of the transparent support of the optical compensation sheet and the transmission axis of the polarizing film are arranged so as to be substantially parallel. The moisture permeability of the transparent protective film is preferably in the range of 100 to 1000 (g / m ² ) / 24 hrs, and is preferably 300 to 700 (g / m ² ).
/ 24 hrs is more preferable. The polarizing film includes an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film. The iodine-based polarizing film and the dye-based polarizing film are generally manufactured using a polyvinyl alcohol-based film.

[Liquid Crystal Display Device] The optical compensatory sheet or the polarizing plate having the optical compensatory sheet is advantageously used for a liquid crystal display device, especially for a transmission type liquid crystal display device. The transmission type liquid crystal display device includes a liquid crystal cell and two polarizing plates disposed on both sides of the liquid crystal cell. A liquid crystal cell carries a liquid crystal between two electrode substrates. When the optical compensatory sheet is used for a liquid crystal display device, one optical compensatory sheet according to the present invention is disposed between the liquid crystal cell and one of the polarizers, or the optical compensatory sheet is provided between the liquid crystal cell and both the polarizers. Two optical compensation sheets according to the invention are arranged. When a polarizing plate is used for a liquid crystal display device, a polarizing plate having an optical compensation sheet according to the present invention may be used instead of one of the two polarizing plates. Instead of both polarizing plates, a polarizing plate having the optical compensation sheet according to the present invention may be used. When a polarizing plate having an optical compensation sheet according to the present invention is used for a liquid crystal display device, the polarizing plate is arranged such that the optical compensation sheet used as a protective film thereof is on the liquid crystal cell side.

The liquid crystal cell has a TN mode, an ECB mode,
Preferably, the mode is a VA mode or an OCB mode. The VA mode includes an MVA mode. In a TN mode liquid crystal cell, rod-like liquid crystal molecules are substantially horizontally aligned when no voltage is applied, and further twisted at 60 to 120 °. The TN mode liquid crystal cell is a color TFT
It is most frequently used as a liquid crystal display device, and is described in many documents.

In a VA mode liquid crystal cell, rod-like liquid crystal molecules are oriented substantially vertically when no voltage is applied. VA
The liquid crystal cell of the mode includes (1) a VA mode liquid crystal cell in a narrow sense in which rod-like liquid crystal molecules are aligned substantially vertically when no voltage is applied, and substantially horizontally when a voltage is applied (Japanese Patent Laid-Open No. 2-176625). In addition, (2) VA mode is multi-domain (M) for widening the viewing angle.
Liquid crystal cell (VA mode) (SID97, Digest of tec)
h. Papers (Preprints) 28 (1997) 845),
(3) A liquid crystal cell (n-ASM mode) in which rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is performed when voltage is applied (Preprints 58 to 59 (1998). ) Described), (4) SU
RVAIVAL mode liquid crystal cell (presented at LCD International 98) and (5) CPA mode liquid crystal cell (presented at SID01).

The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned (symmetrically) in substantially opposite directions at the top and bottom of the liquid crystal cell. A liquid crystal display using a bend alignment mode liquid crystal cell is disclosed in U.S. Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is OCB (Optically Compensated).
(atory Bend) Also called liquid crystal mode. The bend alignment mode liquid crystal display device has an advantage that the response speed is high.
TN mode liquid crystal cells are most frequently used as color TFT liquid crystal display devices, and are described in many documents. The ECB mode liquid crystal cell is one of the liquid crystal modes that have been studied for the longest time, and is described in many documents.

[0086]

EXAMPLES Example 1 (Preparation of Cellulose Acetate Solution) The following composition was charged into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

<< Composition of Cellulose Acetate Solution >>セ ル ロ ー ス 100% by mass of cellulose acetate having a degree of acetylation of 60.9% triphenyl phosphate (plasticizer) 7 0.8 parts by mass Biphenyldiphenyl phosphate (plasticizer) 3.9 parts by mass Methylene chloride (first solvent) 300 parts by mass Methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass ────────────────────────────────

(Preparation of Retardation Raising Agent Solution) Into another mixing tank, 16 parts by weight of the following retardation raising agent, 80 parts by weight of methylene chloride and 20 parts by weight of methanol were added, and stirred while heating. A solution of the formulation was prepared.

[0089]

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(Preparation of Transparent Support) 475 parts by mass of the cellulose acetate solution was added to the retardation increasing solution 25.
Parts by mass were mixed and stirred to prepare a dope. The addition amount of the retardation increasing agent is cellulose acetate 10
It was 3.0 parts by mass with respect to 0 parts by mass. The obtained dope was cast using a cooling drum casting machine to produce a cellulose acetate film used as a transparent support. About the produced cellulose acetate film,
When the retardation value at a wavelength of 633 nm was measured using an ellipsometer (M-150, manufactured by JASCO Corporation), the Re retardation value was 10 nm, and R
The th retardation value was 81 nm.

(Formation of Undercoat Layer) On one surface of the transparent support, a coating solution having the following composition was applied at 28 ml / m ² and dried to form a 0.1 μm thick gelatin undercoat layer.

<< Composition of Undercoat Layer Coating Solution >>ゼ ラ チ ン Gelatin 0.542 parts by mass Formaldehyde 0.135 parts by mass Salicylic acid 0.160 parts by mass Acetone 39 .1 part by mass Methanol 15.8 parts by mass Methylene chloride 40.6 parts by mass Water 1.2 parts by mass ─────────────────────────── ─────────

(Formation of Second Undercoat Layer) On the undercoat layer,
7 ml / m ² of a coating solution having the following composition is applied, dried,
A second undercoat layer was formed.

<< Composition of Second Undercoat Layer Coating Solution >> ──────────────────────────────── 0.079 parts by mass of the following anionic copolymer: monoethyl citrate 1.01 Parts by mass acetone 20 parts by mass methanol 87.7 parts by mass water 4.05 parts by mass ──────────────────────────────── ────

[0095]

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(Formation of Back Layer) A coating solution having the following composition was applied at 25 ml / m ² on the side of the support opposite to the undercoat layer, and dried to form a back layer.

組成 Composition of coating solution for back layer ──────セ ル ロ ー ス Cellulose diacetate with a degree of acetylation of 55% 0.656 parts by mass Silica with an average particle size of 1 μm Matting agent 0.065 parts by mass Acetone 67.9 parts by mass Methanol 10.4 parts by mass ────────────────────────────── ──────

(Formation of Alignment Film) On the second undercoat layer, a coating solution having the following composition was applied using a # 16 wire bar coater.
8 ml / m ^{2 was} applied. It was dried for 60 seconds with warm air of 60 ° C. and further for 150 seconds with warm air of 90 ° C. Next, a rubbing treatment was performed on the formed film in the longitudinal direction of the cellulose acetate film (transparent support).

<< Composition of Alignment Film Coating Solution >>変 性 The following modified polyvinyl alcohol: 8 parts by mass Unmodified polyvinyl alcohol (PVA217, manufactured by Kuraray Co., Ltd.) 2 parts by mass Water 371 parts by mass Methanol 119 parts by mass Glutaraldehyde (crosslinking agent) 0.5 part by mass ─────────────────────────── ─────────

[0100]

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(Formation of Optically Anisotropic Layer) On the alignment film, 41.01 g of the following discotic liquid crystal molecules, and ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 2.03
g, dipentaerythritol hexaacrylate (KY
ARAD DPHA, Nippon Kayaku Co., Ltd.) 2.03 g,
Cellulose acetate butyrate (CAB551-0.
2. 0.90 g of Eastman Chemical Co., Ltd., 0.23 g of cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co.), 1.35 g of photopolymerization initiator (Irgacure 907, Ciba Geigy), sensitization (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.4
A coating solution of 5 g dissolved in 102 g of methyl ethyl ketone was applied with a # 4 wire bar. This was affixed to a metal frame and heated in a thermostat at 130 ° C. for 2 minutes to align discotic liquid crystal molecules. Next, at 80 ° C
In an atmosphere of about 100 ° C. in an atmosphere of
Ultraviolet rays were irradiated for 0.4 seconds using a W / cm high-pressure mercury lamp to copolymerize the discotic liquid crystal molecules, the polyfunctional monomer (dipentaerythritol hexaacrylate), and the alignment film polymer (modified polyvinyl alcohol). Then, it was left to cool to room temperature. In this way, an optically anisotropic layer was formed, and an optical compensation sheet was produced. When the retardation value of the optically anisotropic layer was measured at a wavelength of 633 nm, the Re retardation value was 48 nm. The average angle (average tilt angle) between the disc surface of the discotic liquid crystal molecules and the transparent support surface was 42 °.

[0102]

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(Preparation of Polarizing Plate) A polarizing film was prepared by adsorbing iodine on a stretched polyvinyl alcohol film. Next, the transparent support back layer side of the produced optical compensation sheet was adhered to one side of the polarizing film using a polyvinyl alcohol-based adhesive. It was arranged so that the slow axis of the transparent support was parallel to the transmission axis of the polarizing film. A commercially available cellulose triacetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) is saponified, and a polyvinyl alcohol-based adhesive is used as a transparent protective film on the opposite side of the polarizing film (with no optical compensation sheet attached). Side). The slow axis of the transparent protective film and the transmission axis of the polarizing film were arranged so as to be orthogonal to each other. Thus, a polarizing plate with an optical compensation sheet was produced.

(Evaluation of Reworkability) The produced polarizing plate with an optical compensation sheet was adhered to a glass plate via an adhesive. The polarizing plate was arranged such that the optical compensation sheet side (optically anisotropic layer side) of the polarizing plate was on the glass surface side. The polarizing plate with an optical compensation sheet attached to a glass plate was aged at 50 ° C. and 5 atm for 6 hours. The condition was returned to 25 ° C. and the relative humidity was 60 ° C., and the polarizing plate with the optical compensation sheet was peeled off from the glass plate. When the above test operation was performed on 100 polarizing plates, all 100 polarizing plates could be peeled off from the glass plate without any problem (no peeling).

(Preparation of Liquid Crystal Display Device) A pair of polarizing plates provided in a commercially available TN mode liquid crystal display device (6E-A3, manufactured by Sharp Corporation) was peeled off, and two polarizing plates prepared instead were used. Then, the optical compensation sheet was bonded to the liquid crystal cell side via an adhesive. Thus, a liquid crystal display device was manufactured. The transmission axis of the polarizing plate on the observer side and the transmission axis on the backlight side were arranged so as to be in the O mode. About the manufactured liquid crystal display device, a measuring device (EZ-Co
The viewing angle was measured in eight steps from black display (L1) to white display (L8) using an Ntrast 160D (manufactured by ELDIM). As a specific viewing angle, the contrast ratio is 1
0 or more, black side gradation inversion (inversion between L1 and L2)
There was no angle sought. As a result, a wide viewing angle of 70 ° on the upper side, 45 ° on the lower side, and 160 ° on the left and right sides was obtained.

Example 2 (Preparation of Cellulose Acetate Solution) Two types of cellulose acetate solutions (inner layer dope and outer layer dope) comprising the following compositions were prepared. The dope for the inner layer is 5
The solution was filtered at 0 ° C. with a filter paper (# 63, manufactured by Toyo Roshi Kaisha, Ltd.) having an absolute filtration accuracy of 0.01 mm. The dope for the outer layer is 50
Filter paper (FH0) with an absolute filtration accuracy of 0.0025 mm
25, manufactured by Pall Corporation).

組成 Composition of Cellulose Acetate Solution Dope for Inner Layer Dope for Outer Layer ─ ─────────────────────────────────── Degree of acetylation 60.5% Cellulose acetate 100 parts by mass 100 parts by mass Triphenyl phosphate 7.8 parts by mass 7.8 parts by mass Biphenyldiphenyl phosphate 3.9 parts by mass 3.9 parts by mass Retardation increasing agent used in Example 1 3.0 parts by mass 3.0 parts by mass methylene chloride 1 solvent) 450 parts by mass 481 parts by mass Methanol (second solvent) 39 parts by mass 42 parts by mass ───────

(Preparation of Transparent Support) Using a three-layer co-casting die, the dope for the inner layer was placed inside and the dope for the outer layer was placed on both sides, and discharged on the metal support at the same time. Then, it was layered and cast. The casting amount is 45 μm for the inner layer.
m and the thickness of the outer layer were each set to 5 μm. The cast film was peeled off from the support, uniaxially stretched 30% horizontally with a tenter, and dried to produce a cellulose acetate film. After drying at 70 ° C. for 3 minutes and at 120 ° C. for 5 minutes, the film was peeled off from the support, and dried at 130 ° C.
Drying was carried out stepwise at 30 ° C. for 30 minutes to obtain a cellulose acetate film used as a support. The residual solvent amount is
It was 0.5% by mass. When the retardation value of the produced cellulose acetate film at a wavelength of 633 nm was measured using an ellipsometer (M-150, manufactured by JASCO Corporation), the Re retardation value was 38 nm, and the Rth retardation value was 230 nm.
Met.

(Saponification of Transparent Support)
After being immersed in a 2.0 N aqueous solution of potassium hydroxide at 25 ° C. for 2 minutes, it was neutralized with sulfuric acid, washed with pure water, and dried. Thereafter, when the surface energy of the transparent support was determined by a contact angle method, it was 63 mN / m.

(Formation of Alignment Film) On a saponified transparent support, an alignment film coating solution having the composition used in Example 1 was coated with # 16.
Was applied with a wire bar coater of 28 ml / m ² . 6
Drying was performed with hot air at 0 ° C. for 60 seconds and further with hot air at 90 ° C. for 150 seconds. Next, a rubbing treatment was performed on the formed film in a direction at an angle of 45 ° to the longitudinal direction of the cellulose acetate film (transparent support).

(Formation of Optically Anisotropic Layer) On the alignment film, the discotic liquid crystalline molecules 41.01 used in Example 1 were formed.
g, ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.)
1.22 g, polyfunctional acrylate monomer (NK ester A-TMMT, manufactured by Shin-Nakamura Chemical Co., Ltd.) 2.84
g, cellulose acetate butyrate (CAB551-
0.2, 0.90 g of Eastman Chemical Co., Ltd., 0.23 g of cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co.), 1.35 g of photopolymerization initiator (Irgacure 907, Ciba Geigy),
Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.)
A coating solution in which 0.45 g was dissolved in 102 g of methyl ethyl ketone was applied using a # 4 wire bar. This was affixed to a metal frame and heated in a thermostat at 130 ° C. for 2 minutes to align discotic liquid crystal molecules. next,
In a state where the film surface temperature becomes about 100 ° C. in an atmosphere of 80 ° C.,
Ultraviolet rays were irradiated for 0.4 seconds using a 120 W / cm high-pressure mercury lamp to copolymerize the discotic liquid crystalline molecules, the polyfunctional acrylate monomer, and the alignment film polymer (modified polyvinyl alcohol). Then, it was left to cool to room temperature. In this way, an optically anisotropic layer was formed, and an optical compensation sheet was produced. When the retardation value of the optically anisotropic layer was measured at a wavelength of 633 nm, the Re retardation value was 45 nm. The average angle (average tilt angle) between the disc surface of the discotic liquid crystal molecules and the transparent support surface was 39 °.

(Preparation of Polarizing Plate) Using the prepared optical compensatory sheet, the slow axis of the transparent support and the transmission axis of the polarizing film were 4
A polarizing plate was produced in the same manner as in Example 1 except that the polarizing plate was arranged at an angle of 5 °.

(Evaluation of Reworkability) The produced polarizing plate was bonded to a glass plate via an adhesive. The optical compensation sheet was disposed so as to be on the glass surface side. The polarizing plate attached to the glass plate was aged at 50 ° C. and 5 atm for 6 hours. After returning to 25 ° C. and a relative humidity of 60 ° C., the polarizing plate was peeled off from the glass plate. When the above test operation was performed on 100 polarizing plates, all 100 polarizing plates were
The film could be peeled off from the glass plate without any problem (no peeling).

(Preparation of Bend Alignment Liquid Crystal Cell) A polyimide film was provided as an alignment film on a glass substrate with an ITO electrode, and the alignment film was subjected to a rubbing treatment. The two glass substrates thus obtained were opposed to each other in an arrangement in which the rubbing directions were parallel, and the cell gap was set to 6 μm. A rod-like liquid crystalline molecule having a Δn of 0.1396 (ZLI113
2, manufactured by Merck Co., Ltd.) to produce a bend alignment liquid crystal cell.

(Preparation of Liquid Crystal Display) Two polarizing plates were attached so as to sandwich the prepared bend alignment cell. The optically anisotropic layer of the polarizing plate was arranged so as to face the cell substrate, and the rubbing direction of the liquid crystal cell was antiparallel to the rubbing direction of the optically anisotropic layer facing the cell substrate. A rectangular wave voltage of 55 Hz was applied to the liquid crystal cell of the manufactured liquid crystal display device. A normally white mode of 2 V for white display and 5 V for black display was set. The transmittance ratio (white display / black display) is defined as a contrast ratio, and a measuring device (EZ-Contrast 160D, EL
DIM) from black display (L1) to white display (L
The viewing angle was measured in eight steps up to 8). As a specific viewing angle, an angle having a contrast ratio of 10 or more and no black-side gradation inversion (inversion between L1 and L2) was determined. As a result, 80 ° on the upper side, 80 ° on the lower side, and 8 on the left and right
A wide viewing angle of 0 ° was obtained.

Example 3 (Preparation of Cellulose Acetate Solution) A cellulose acetate solution (dope) comprising the following composition was prepared.

<< Composition of Cellulose Acetate Solution >>セ ル ロ ー ス 100 parts by mass of cellulose acetate having a degree of acetylation of 59.5% 7.8 parts by mass of triphenyl phosphate Biphenyldiphenyl phosphate 3.9 parts by mass Retardation enhancer used in Example 1 2.0 parts by mass Methyl acetate 306 parts by mass Cyclohexanone 122 parts by mass Methanol 30.5 parts by mass Ethanol 30.5 parts by mass Silica having an average particle diameter of 20 nm Fine particles 1.0 parts by mass ────────────────────────────────────

(Preparation of Transparent Support) The prepared dope was cast on a metal support. After drying at 70 ° C. for 3 minutes and at 120 ° C. for 5 minutes, the film was peeled off from the support, and dried at 130 ° C.
For 50 minutes to obtain a cellulose acetate film used as a support. The residual solvent amount was 0.8% by mass. About the produced cellulose acetate film, an ellipsometer (M-150, JASCO Corporation)
The retardation value at a wavelength of 633 nm was measured using the following method.
The m and Rth retardation values were 50 nm.

(Saponification of Transparent Support)
2.0N aqueous potassium hydroxide solution is applied at 70 ° C.
After 0 second, the product was washed with pure water and dried. Thereafter, when the surface energy of the transparent support was determined by the contact angle method, it was 6
It was 5 mN / m.

(Formation of Alignment Film and Optically Anisotropic Layer) The surface of the cellulose acetate film on the saponified side was
An alignment film and an optically anisotropic layer were formed in the same manner as in Example 1 (without providing an undercoat layer). In this way,
An optical compensation sheet was produced.

[Example 4] (Saponification treatment of transparent support) A 1.5N potassium hydroxide solution (solvent: water / isopropyl alcohol / polyethylene glycol = 14 /
86/15% by volume) was applied at 5 ml / m ² and kept at 60 ° C. for about 10 seconds. The potassium hydroxide remaining on the film surface was washed with water and dried. When the surface energy of the transparent support was determined by the contact angle method, it was 63 mN / m.

(Formation of Alignment Film and Optically Anisotropic Layer) On the saponified side of the cellulose acetate film,
An alignment film and an optically anisotropic layer were formed in the same manner as in Example 1 (without providing an undercoat layer). In this way,
An optical compensation sheet was produced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a basic configuration of a transmission type liquid crystal display device.

FIG. 2 is a schematic diagram showing another basic configuration of a transmission type liquid crystal display device.

FIG. 3 is a schematic diagram showing still another basic configuration of the transmission type liquid crystal display device.

FIG. 4 is a schematic diagram showing a basic configuration of a reflection type liquid crystal display device.

[Explanation of symbols]

 BL backlight RP reflector 1, 1a, 1b, 3, 3a, 3b Transparent protective film 2, 2a, 2b Polarizing film 4, 4a, 4b Transparent support 5, 5a, 5b Optically anisotropic layer 6a, 6b Liquid crystal cell Substrates 7 Rod-like liquid crystalline molecules

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H049 BA06 BA42 BB03 BB49 BC09 BC22 2H091 FA11X FA11Z FB02 GA06 LA02 4F205 AA01 AG03 GA07 GB02 GB26 GC02 GC07

Claims (12)

[Claims] 1. An optical compensation sheet comprising an optically anisotropic layer formed from liquid crystal molecules and a transparent support, wherein the optically anisotropic layer further comprises four or more double bonds in the molecule. An optical compensation sheet comprising a polymer of a functional monomer. 2. The optical compensation sheet according to claim 1, wherein the polyfunctional monomer is an ester of a polyol having four or more hydroxyls in a molecule and acrylic acid or methacrylic acid. 3. The optical compensation sheet according to claim 1, wherein the liquid crystal molecules are discotic liquid crystal molecules. 4. The optical compensation sheet according to claim 3, wherein the discotic liquid crystalline molecule has a double bond, and the discotic liquid crystalline molecule and a polyfunctional monomer are copolymerized. 5. The optical compensation sheet according to claim 1, wherein an alignment film is provided between the optically anisotropic layer and the transparent support. 6. The optical compensation sheet according to claim 5, wherein the alignment film comprises a polymer having a double bond in a side chain, and the polymer of the alignment film and a polyfunctional monomer are copolymerized. 7. The optical compensation sheet according to claim 1, wherein the transparent support has a Re retardation value of 0 to 50 nm and an Rth retardation value of 70 to 400 nm. 8. The transparent support has a content of 59.0 to 61.5%.
The optical compensation sheet according to claim 1, comprising a cellulose acetate film having a degree of acetylation. 9. The cellulose acetate film contains an aromatic compound having at least two aromatic rings in an amount of 0.01 to 20 parts by mass per 100 parts by mass of cellulose acetate.
The optical compensatory sheet according to claim 8, comprising parts by mass. 10. The optical compensation sheet according to claim 8, wherein the cellulose acetate film is formed by a co-casting method. 11. A cellulose acetate film is formed from a cellulose acetate solution using an ether having 2 to 12 carbon atoms, a ketone having 3 to 12 carbon atoms or an ester having 2 to 12 carbon atoms as a solvent. An optical compensation sheet according to claim 8. 12. A liquid crystal display device comprising a liquid crystal cell and two polarizing plates disposed on both sides thereof, wherein at least one optical compensation sheet is disposed between the liquid crystal cell and at least one polarizing plate. The optical compensation sheet has an optically anisotropic layer formed from liquid crystal molecules and a transparent support, and the transparent support may function as a transparent protective film of the polarizing plate. And a polymer of a polyfunctional monomer having four or more double bonds in the molecule.