JP2001089657A - Liquid crystal orientated film, optical compensation sheet, stn-type liquid crystal display device and orientating discotic liquid crystalline molecule - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical compensating sheet suitable for a STN-type liquid crystal display device by mono domain-orientating a discotic liquid crystalline molecule substantially in a vertical and uniform direction. SOLUTION: A polyamic acid having a repeating unit containing a polymerizable group represented by the formula is employed to obtain the objective orientated film (wherein X is a tetravalent group including an aromatic ring, an alicyclic ring or a heterocyclic ring; Y is a divalent group including an aromatic ring provided that at least one of X and Y has a 10-100C hydrocarbon group as a substituent group; L0 is a divalent connecting group selected from a group composed of a single bond, -O-, -CO-, -S-, -SO2-, -NH-, an alkylene group, an alkenylene group, alkynylene group, an arylene group and a combination thereof; Q is a polymerizable group; R1 is -L0-Q or -O-M; M is an atom or a group selected from a group composed of a hydrogen atom, an alkali metal atom and an ammonium group which may have a substituent group).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal alignment film provided on a support for aligning a liquid crystal. The present invention also relates to a method for orienting liquid crystalline molecules at an average inclination angle in the range of 50 to 90 degrees with respect to the plane of the support. Furthermore, the present invention also relates to an optical compensation sheet having an optically anisotropic layer formed from discotic liquid crystalline molecules on a transparent support. Furthermore, the present invention relates to S
The invention also relates to a TN liquid crystal display device.

[0002]

2. Description of the Related Art An STN-type liquid crystal display device has a structure including an STN-type liquid crystal cell, two polarizing plates, and an optical compensation sheet (retardation plate) provided between the STN-type liquid crystal cell and the polarizing plate. The liquid crystal cell is composed of 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 STN type liquid crystal cell,
An alignment film for aligning rod-like liquid crystal molecules is provided on two substrates. Further, using a chiral agent, the rod-like liquid crystal molecules are twist-aligned at an angle of 90 degrees or more, particularly 180 to 360 degrees.

In an STN type liquid crystal display device without an optical compensation sheet, a display image is colored blue or yellow due to the birefringence of the rod-like liquid crystal molecules. Coloring of the displayed image is inconvenient in both monochrome display and color display. The optical compensation sheet is used to eliminate such coloring and obtain a bright and clear image. The optical compensation sheet also
In some cases, a function of increasing the viewing angle of the liquid crystal cell is provided. As the optical compensation sheet, a stretched birefringent film has been conventionally used. S using stretched birefringent film
Optical compensatory sheets for TN liquid crystal display devices are described in JP-A-7-104284 and JP-A-7-13021.

It has been proposed to use an optical compensatory sheet having an optically anisotropic layer containing discotic liquid crystal molecules on a transparent support instead of an optical compensatory sheet comprising a stretched birefringent film. The optically anisotropic layer is formed by aligning discotic liquid crystal molecules and fixing the alignment state. Discotic liquid crystalline molecules generally have a large birefringence. The discotic liquid crystal molecules have various alignment forms. The use of discotic liquid crystal molecules makes it possible to produce an optical compensatory sheet having optical properties that cannot be obtained with a conventional stretched birefringent film. An optical compensatory sheet using discotic liquid crystal molecules is disclosed in JP-A-6-214116, US Pat.
Nos. 3,679, 5,646,703 and German Offenlegungsschrift 3,911,620 A1. However, these optical compensation sheets are designed assuming a TN type liquid crystal display device as a main use.

[0005] In the STN type liquid crystal display device, as described above, rod-like liquid crystal molecules having a super-twist orientation larger than 90 degrees are used in the birefringence mode. The STN-type liquid crystal display device has a feature that even in a simple matrix electrode structure having no active element (thin film transistor or diode), a large capacity clear display is possible by time division driving. In order to optically compensate an STN-type liquid crystal cell using discotic liquid crystal molecules, it is necessary to align the discotic liquid crystal molecules substantially vertically (homogeneous alignment). Preferably, the discotic liquid crystalline molecules are further twisted.

Japanese Patent Application Laid-Open No. 9-26572 discloses an optical compensation sheet in which discotic liquid crystal molecules are twisted. Further, the drawings of the publication show a state in which the discotic liquid crystalline molecules are substantially vertically aligned. In the method disclosed in the publication,
After applying and drying a material containing discotic liquid crystal molecules on a glass substrate, a magnetic field is applied in parallel to the substrate, whereby the discotic liquid crystal molecules are oriented substantially vertically.

However, in the above method, a special device is required for the alignment of the discotic liquid crystal molecules, and it is considered that it is difficult to obtain high reproducibility of the alignment.

[0008] Researches have been made to align rod-like liquid crystalline molecules used in liquid crystal cells substantially vertically (homeotropic alignment) using an alignment film. However, it is considered difficult to align discotic liquid crystal molecules substantially vertically from the alignment film interface to the air interface only by using the alignment film for rod-like liquid crystal molecules. Therefore, there is a need for a method for aligning discotic liquid crystal molecules substantially vertically from the alignment film interface to the air interface without using a special device. In addition, in order to improve the durability of the liquid crystal element, it is necessary to make the alignment film have the function.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for aligning liquid crystal molecules (particularly discotic liquid crystal molecules) substantially vertically and imparting a function of improving the durability of a liquid crystal element. Another object of the present invention is to provide a liquid crystal alignment film having a function of adhering to an optically anisotropic layer and enabling vertical alignment. Another object of the present invention is to provide a method for stably aligning liquid crystal molecules in a vertical and uniform direction. Still another object of the present invention is to provide an optical compensation sheet particularly suitable for an STN type liquid crystal display device. Still another object of the present invention is to provide an STN type liquid crystal display device capable of obtaining a clear image with high contrast.

[0010]

The present invention is directed to a liquid crystal alignment film provided on a transparent support, wherein the liquid crystal alignment film contains a polymer having a repeating unit represented by the following formula. Liquid crystal alignment film:

[0011]

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[Wherein, X represents a tetravalent group containing an aromatic ring, an aliphatic ring or a heterocyclic ring; Y represents a divalent group containing an aromatic ring; At least one of them has a hydrocarbon group having 10 to 100 carbon atoms as a substituent; L ⁰ is a single bond, -O-, -CO-,-
_{S -, - SO 2 -,} - NH-, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a divalent linking group selected from the group consisting of; Q represents a polymerizable group R ¹ represents -L ⁰ -Q or -OM; M represents a hydrogen atom, an alkali metal atom,
And an atom or group selected from the group consisting of an ammonium group which may have a substituent.

A preferred embodiment of the liquid crystal alignment film of the present invention is a liquid crystal alignment film characterized in that the hydrocarbon group having 10 to 100 carbon atoms has a steroid group.

The present invention also provides an optical compensatory sheet having, in this order, a liquid crystal alignment film and an optically anisotropic layer formed from discotic liquid crystalline molecules on a transparent support. formula:

[0015]

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[Wherein, X represents a tetravalent group containing an aromatic ring, an aliphatic ring or a hetero ring; Y represents a divalent group containing an aromatic ring; At least one of them has a hydrocarbon group having 10 to 100 carbon atoms as a substituent; L ⁰ is a single bond, -O-, -CO-,-
_{S -, - SO 2 -,} - NH-, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a divalent linking group selected from the group consisting of; Q represents a polymerizable group R ¹ represents -L ⁰ -Q or -OM; M represents a hydrogen atom, an alkali metal atom,
And an atom or a group selected from the group consisting of an ammonium group which may have a substituent.] And a discotic liquid crystalline molecule having a repeating unit represented by 50 to the transparent support surface. There is also an optical compensatory sheet characterized in that the optical compensatory sheet is oriented at an average inclination angle in a range of from 90 to 90 degrees.

In a preferred embodiment of the optical compensatory sheet of the present invention, the discotic liquid crystalline molecules in the optically anisotropic layer are twisted and oriented, and the twist angle is in the range of 90 to 360 degrees. It is an optical compensation sheet.

The present invention further provides an STN type liquid crystal cell, a polarizing plate disposed on both sides of the STN type liquid crystal cell, and an STN comprising an optical compensation sheet disposed between the STN type liquid crystal cell and one or both polarizing plates. Type liquid crystal display device, wherein the optical compensation sheet has a transparent support, a liquid crystal alignment film and an optically anisotropic layer formed from discotic liquid crystal molecules in this order from the polarizing plate side, and the liquid crystal alignment film is formula:

[0019]

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[In the formula, X represents a tetravalent group containing an aromatic ring, an aliphatic ring or a hetero ring; Y represents a divalent group containing an aromatic ring; At least one of them has a hydrocarbon group having 10 to 100 carbon atoms as a substituent; L ⁰ is a single bond, -O-, -CO-,-
_{S -, - SO 2 -,} - NH-, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a divalent linking group selected from the group consisting of; Q represents a polymerizable group R ¹ represents -L ⁰ -Q or -OM; M represents a hydrogen atom, an alkali metal atom,
And an atom or group selected from the group consisting of an ammonium group which may have a substituent], and a discotic liquid crystal molecule in the optically anisotropic layer is a polymer having a repeating unit represented by The STN type liquid crystal display device is characterized in that the liquid crystal display device is oriented at an average inclination angle of 50 to 90 with respect to the surface of the transparent support while being twisted in the range of 90 to 360 degrees.

The present invention further provides the following formula:

[0022]

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[In the formula, X represents a tetravalent group containing an aromatic ring, an aliphatic ring or a heterocyclic ring; Y represents a divalent group containing an aromatic ring; At least one of them has a hydrocarbon group having 10 to 100 carbon atoms as a substituent; L ⁰ is a single bond, -O-, -CO-,-
_{S -, - SO 2 -,} - NH-, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a divalent linking group selected from the group consisting of; Q represents a polymerizable group R ¹ represents -L ⁰ -Q or -OM; M represents a hydrogen atom, an alkali metal atom,
And represents an atom or group selected from the group consisting of an ammonium group which may have a substituent] by using a liquid crystal alignment film containing a polymer having a repeating unit represented by the following formula: There is also a method of aligning discotic liquid crystalline molecules at an average tilt angle in the range of from 90 to 90 degrees.

In the present specification, the average tilt angle of the discotic liquid crystal molecules means the average angle between the disc surface of the discotic liquid crystal molecules and the surface of the support (or the surface of the alignment film). The state in which the discotic liquid crystal molecules are oriented at an average tilt angle in the range of 50 to 90 degrees is referred to as the discotic liquid crystal molecules being substantially vertically oriented.

[0025]

As a result of research, the present inventor has found that a polymer having a repeating unit of a partial condensate of a tetracarboxylic acid having a polymerizable group and a diamine as a repeating unit is used as a liquid crystal alignment film, and that the liquid crystal alignment is improved with respect to the alignment film surface. The molecules were successfully oriented vertically. The liquid crystal alignment film having the above polymer has a better function as a vertical alignment film than a conventional alignment film, and can stably align liquid crystal molecules in a substantially vertical and uniform direction. In a conventional vertical alignment film, liquid crystal molecules are vertically aligned by injecting liquid crystal molecules between two substrates having a vertical alignment film. However, when the number of substrates having a vertical alignment film was one, the tilt angle of liquid crystal molecules near the interface (air interface) opposite to the substrate was small, and the vertical alignment of liquid crystal molecules was insufficient. When the liquid crystal alignment film of the present invention is used, vertical alignment of liquid crystalline molecules can be achieved using only one substrate. In addition, when two substrates are used, a better vertical alignment can be achieved than in the past. Further, by using the vertical alignment film of the present invention, the polymer and a liquid crystal molecule having a polymerizable group,
Since it can be chemically bonded via the interface between the vertical alignment film and the optically anisotropic layer, the adhesion between the vertical alignment film and the transparent support or the optically anisotropic layer is improved. Thereby, the durability of the liquid crystal element using the liquid crystal alignment film can be improved. By obtaining a means for stably aligning discotic liquid crystalline molecules in a substantially vertical and uniform direction and a means for further improving adhesion, ST
It has become possible to manufacture an optical compensation sheet suitable for an N-type liquid crystal display device. By using an optical compensation sheet in which discotic liquid crystal molecules are substantially vertically aligned (preferably, further twisted), a clear image with high contrast can be obtained.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an alignment state of rod-like liquid crystal molecules in a liquid crystal cell and a discotic liquid crystal in an optically anisotropic layer in a pixel portion of a STN type liquid crystal display device where no voltage is applied (off). FIG. 3 is a cross-sectional view schematically illustrating an orientation state of a hydrophilic molecule. As shown in FIG. 1, the liquid crystal cell includes an upper substrate (1
1) Between the lower alignment film (12) and the upper alignment film (14) of the lower substrate (15), rod-like liquid crystal molecules (13a-1)
3e) has a liquid crystal layer formed therein. Alignment film (1
Due to the functions of the chiral agent added to the liquid crystal layer and the chiral agent added to the liquid crystal layer, the rod-like liquid crystal molecules (13a to 13e) are twisted as shown in FIG. Although omitted in FIG. 1, the upper substrate (11) and the lower substrate (15) of the liquid crystal cell each have an electrode layer. The electrode layer has a function of applying a voltage to the rod-like liquid crystal molecules (13a to 13e). S
When the applied voltage of the TN type liquid crystal cell is 0 (when no voltage is applied), as shown in FIG.
3e) is oriented substantially parallel (in the horizontal direction) to the plane of the alignment films (12, 14). Then, rod-like liquid crystalline molecules (1
3a to 13e) are oriented in such a manner as to form a spiral in a horizontal plane (approximately 240 degrees counterclockwise from 13a to 13e in FIG. 1) while being twisted along the thickness direction. When a voltage is applied (turned on) to the STN-type liquid crystal cell, the rod-like liquid crystal molecules (13b to 13b) at the center of the liquid crystal cell are applied.
13d) is oriented more vertically (rearranged in parallel to the direction of the electric field) as compared to when no voltage is applied (off). Alignment film (1
The alignment state of the rod-like liquid crystal molecules (13a, 13e) near (2, 14) does not substantially change even when a voltage is applied.

An optical compensation sheet is disposed below the liquid crystal cell. The optical compensation sheet shown in FIG. 1 has an alignment film (22) and an optically anisotropic layer on a transparent support (23) in this order. The optically anisotropic layer is a layer obtained by aligning discotic liquid crystal molecules (21a to 21e) and fixing the molecules in the aligned state. In the present invention, as shown in FIG. 1, discotic liquid crystal molecules (21a
21e) is oriented substantially perpendicular to the plane of the alignment film (22). And, as shown in FIG.
The discotic liquid crystal molecules (21a to 21e) spiral in a horizontal plane while being twisted along the thickness direction (in FIG. 1, approximately 24 clockwise from 21a to 21e).
(0 degree). In FIG. 1, rod-like liquid crystal molecules and discotic liquid crystal molecules are 13a and 21e, 13b and 21d, and 13c and 21c.
c, 13d and 21b, and 13e and 21a have a corresponding relationship. That is, the discotic liquid crystal molecules 21e optically compensate the rod-like liquid crystal molecules 13a, and similarly, the discotic liquid crystal molecules 21a optically compensate the rod-like liquid crystal molecules 13e. Each correspondence will be described with reference to FIG.

FIG. 2 is a schematic diagram showing the refractive index ellipsoids of the rod-like liquid crystal molecules of the liquid crystal cell and the discotic liquid crystal molecules of the optical compensatory sheet which has a relationship of optically compensating the rod-like liquid crystal molecules. The refractive index ellipsoid (13) of the rod-like liquid crystal molecules of the liquid crystal cell has a refractive index (1) in a plane parallel to the alignment film.
3x, 13y) and the refractive index (13) in the thickness direction of the liquid crystal cell.
z). In the STN type liquid crystal cell, the refractive index (13x) in one direction in a plane parallel to the alignment film has a large value, and the refractive index (13y) in the plane perpendicular to the direction and the refractive index (13x) in the thickness direction of the liquid crystal cell (13x). 13z) is a small value. Therefore, the refractive index ellipsoid (13) has a shape in which a rugby ball is laid horizontally as shown in FIG. In such a liquid crystal cell having a non-spherical refractive index ellipsoid,
Angle dependence of birefringence occurs. This angle dependency is eliminated by using an optical compensation sheet.

The refractive index ellipsoid (21) of the discotic liquid crystal molecules of the optical compensatory sheet which has a relation of optically compensating the rod-like liquid crystal molecules also has a refractive index (21x, 21y) in a plane parallel to the alignment film. It is formed by the refractive index (21z) in the thickness direction of the optically anisotropic layer. In the present invention, by aligning the discotic liquid crystal molecules substantially vertically, the refractive index (21x) in one direction in a plane parallel to the alignment film becomes a small value, and the in-plane refraction in the direction perpendicular to that direction is reduced. Rate (2
1y) and the refractive index (21z) in the thickness direction of the optically anisotropic layer
Is a large value. Therefore, the refractive index ellipsoid (21)
Has an upright disk shape as shown in FIG. From the above relationship, the retardation generated in the liquid crystal cell (1) can be offset by the optical compensation sheet (2). That is, the refractive index (13x, 13
y, 13z), the refractive index of discotic liquid crystal molecules (21x, 21y, 21z), the thickness of a rod-shaped liquid crystal molecule layer having the same director direction (13t), and the thickness of the discotic liquid crystal molecule layer (21t) If the liquid crystal display device is designed so as to satisfy the following expression, the angle dependence of the liquid crystal cell can be eliminated. │ (13x-13y) × 13t│ = │ (21x-21
y) × 21t││ (13x-13z) × 13t│ = │ (21x-21
z) × 21t│

FIG. 3 is a schematic diagram showing the layer structure of the STN type liquid crystal display device. In the liquid crystal display device shown in FIG. 3A, the lower polarizing plate (3) is sequentially arranged from the backlight (BL) side.
a), a lower optical compensation sheet (2a), an STN type liquid crystal cell (1), and an upper polarizing plate (3b) in this order. In the liquid crystal display device shown in FIG. 3B, in order from the backlight (BL) side, a lower polarizing plate (3a), a lower optical compensation sheet (2a), an upper optical compensation sheet (2b), and an STN type liquid crystal cell ( 1) and an upper polarizing plate (3b). In the liquid crystal display device shown in FIG. 3 (c), the lower polarizing plate (3a), ST
An N-type liquid crystal cell (1), an upper optical compensation sheet (2b), and an upper polarizing plate (3b) are arranged in this order. In the liquid crystal display device shown in FIG.
From the side, a lower polarizing plate (3a), an STN liquid crystal cell (1), a lower optical compensation sheet (2a), an upper optical compensation sheet (2b), and an upper polarizing plate (3b) are arranged in this order. In the liquid crystal display device shown in FIG. 3E, the lower polarizing plate (3a), the lower optical compensation sheet (2a), the STN type liquid crystal cell (1), and the upper optical compensation sheet ( 2b), and an upper polarizing plate (3b).

FIG. 3 shows the lower polarizing plate (3a) as an arrow.
, The normal (director) direction (DDa) of the discotic liquid crystal molecules near the alignment film of the lower optical compensation sheet (2a) (DDa), and the vicinity of the liquid crystal cell of the lower optical compensation sheet (2a). Direction (DDb) of discotic liquid crystal molecules in the normal direction (director), rubbing direction (RDa) of lower alignment film of liquid crystal cell (1), rubbing direction (RDb) of upper alignment film of liquid crystal cell (1) , The normal (director) direction (D) of the disc surface of the discotic liquid crystalline molecules near the liquid crystal cell of the upper optical compensation sheet (2a).
Dc), the normal (director) direction (DDd) of the discotic liquid crystal molecules near the alignment film of the upper optical compensation sheet (2a) (DDd), and the transmission axis (TAb) of the upper polarizer (3b). . The exact angles are described in FIGS. 4 and 5.

FIG. 4 is a plan view showing preferable optical directions for each element of the STN type liquid crystal display device. FIG.
Is an arrangement that emphasizes front contrast. FIG. 4 (a) shows the lower polarizing plate and ST as shown in FIG. 3 (a).
This is a case where one optical compensation sheet is provided between the liquid crystal cell and the N-type liquid crystal cell. (B) of FIG. 4, as shown in (b) of FIG.
This is a case where two optical compensation sheets are provided between the lower polarizing plate and the STN type liquid crystal cell. FIG. 4 (c) is the same as FIG. 3 (c).
As shown in (1), there is a case where one optical compensation sheet is provided between the STN type liquid crystal cell and the upper polarizing plate. FIG. 4D
FIG. 3D shows a case where two optical compensation sheets are provided between the STN type liquid crystal cell and the upper polarizing plate as shown in FIG. FIG. 4E shows one optical compensation sheet between the lower polarizing plate and the STN liquid crystal cell and between the STN type liquid crystal cell and the upper polarizing plate as shown in FIG. This is a case where one optical compensation sheet is provided in total. X is the standard (0
Degrees), and the meaning of each arrow is shown in FIG.
As described in the above. The transmission axis of the lower polarizing plate (TA
The arrangement may be such that a) and the transmission axis (TAb) of the upper polarizing plate are interchanged.

FIG. 5 is a plan view showing another preferred optical direction for each element of the STN type liquid crystal display device.
FIG. 5 shows an arrangement in which color is emphasized. (A) of FIG.
As shown in FIG. 3A, this is a case where one optical compensation sheet is provided between the lower polarizing plate and the STN type liquid crystal cell. FIG. 5B shows a case where two optical compensation sheets are provided between the lower polarizing plate and the STN liquid crystal cell, as shown in FIG. 3B. FIG. 5C shows a case where one optical compensation sheet is provided between the STN type liquid crystal cell and the upper polarizing plate as shown in FIG. 3C. FIG. 5D shows a case where two optical compensation sheets are provided between the STN liquid crystal cell and the upper polarizing plate, as shown in FIG. 3D. FIG. 5 (e) shows the lower polarizing plate and ST as shown in FIG. 3 (e).
One optical compensation sheet and ST between the N-type liquid crystal cell
This is the case where two optical compensation sheets are provided between the N-type liquid crystal cell and the upper polarizing plate. X is a reference direction (0 degree), and the meaning of each arrow is as described with reference to FIG. The transmission axis (TAa) of the lower polarizing plate and the transmission axis (TAb) of the upper polarizing plate may be interchanged.

Next, each component of the liquid crystal display device will be described in detail. [Support] The type of the support is determined according to the use of the aligned liquid crystal molecules. When liquid crystal molecules are used in a liquid crystal cell, a glass substrate provided with a transparent electrode layer (eg, ITO) is commonly used as a support. Two substrates each having the above-mentioned liquid crystal alignment film formed on the transparent electrode layer are prepared, arranged so that the liquid crystal alignment films face each other, and provided in the gap (described later).
A liquid crystal cell is formed by enclosing rod-like liquid crystal molecules. The gap is formed by the spacer. When liquid crystal molecules are used for the optical compensation sheet, a transparent support made of a polymer film is usually used. It is preferable to use a polymer film having a small optical anisotropy as the transparent support. Transparent support means that the light transmittance is 80% or more. To be small in optical anisotropy, specifically, the in-plane retardation (Re) is preferably 20 nm or less, more preferably 10 nm or less, and most preferably 5 nm or less. Further, the retardation (Rth) in the thickness direction is 100
nm or less, more preferably 50 nm or less, and most preferably 30 nm or less. The in-plane retardation (Re) and the retardation in the thickness direction (Rth) are defined by the following equations, respectively. Re = (nx−ny) × d Rth = [{(nx + ny) / 2} −nz] × d where nx and ny are in-plane refractive indices of the transparent support, and nz is the thickness of the transparent support. Is the refractive index in the direction, and d is the thickness of the transparent support.

Examples of polymers include cellulose esters,
Includes polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate. Cellulose esters are preferred, acetyl cellulose is more preferred, and triacetyl cellulose is most preferred. The polymer film is preferably formed by a solvent casting method. The thickness of the transparent support is
It is preferably 20 to 500 μm, and 50 to 2 μm.
More preferably, it is 00 μm. In order to improve the adhesion between the transparent support and the layer provided thereon (adhesive layer, vertical alignment film or optically anisotropic layer), the transparent support is subjected to a surface treatment (eg, glow discharge treatment, corona discharge treatment, Ultraviolet (UV) treatment, flame treatment) may be performed. An adhesive layer (undercoat layer) may be provided on the transparent support.

[Alignment Film] In the present invention, a polyamic acid or polyamic acid salt containing a partial condensate of a tetracarboxylic acid containing a polymerizable group and a diamine as a repeating unit is used for the liquid crystal alignment film. By introducing a polymerizable group into at least one of the carboxyl groups derived from tetracarboxylic acid, a polymer having the partial condensate as a repeating unit and a liquid crystal molecule having a polymerizable group are optically different from the liquid crystal alignment film. Chemical bonding can be achieved via the interface with the isotropic layer, and the adhesion between the liquid crystal alignment film and the optically anisotropic layer can be improved. Thereby, the durability of the liquid crystal element using the liquid crystal alignment film can be improved. The type of the polymerizable group is determined according to the type of the polymerizable group of the liquid crystal molecule described below.

The repeating unit which is a partial condensate of a tetracarboxylic acid containing a polymerizable group and a diamine is represented by the following formula (I).

[0038]

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In the above formula, X represents a tetravalent group containing an aromatic ring, an aliphatic ring or a heterocyclic ring. Y represents a divalent group containing an aromatic ring. According to the research of the present inventor, in order to vertically align liquid crystal molecules (particularly discotic liquid crystal molecules), the surface energy of the alignment film is reduced by the functional groups of the polymer, and thereby the liquid crystal molecules are set up. State. As the functional group that lowers the surface energy of the alignment film, a hydrocarbon group having 10 to 100 carbon atoms is effective. Therefore, at least one of X and Y is
As a substituent, a hydrocarbon group having 10 to 100 carbon atoms is used.

R ¹ represents -L ⁰ -Q or -OM. L ⁰ is a single bond, -O-, -CO-, -S-, -S
Represents a divalent linking group selected from the group consisting of O ₂ —, —NH—, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a combination thereof. L
⁰ is -O-, -NH-, -O-alkylene-, -NH
-Alkylene-, -O-alkylene-O-, -NH-alkylene-O-, -O-alkylene-CO-O-, -N
H-alkylene-CO-O-, -NH-alkylene-C
O-NH-, -O-alkylene-O-CO-, -O-arylene-O-alkylene-O-CO-, -O-arylene-O-alkylene-O-, -O-arylene, -N
H-alkylene-O-CO- and -NH-arylene-O-alkylene-O-CO- are preferred. Q represents a polymerizable group described in [optically anisotropic layer] described below. The type of the polymerizable group is determined according to the type of the polymerizable group (Q) of the discotic liquid crystal molecule described below. The polymerizable group (Q) of the liquid crystal molecule is, as described later,
It is preferably an unsaturated polymerizable group (Q1 to Q7 exemplified below), an epoxy group (Q8) or an aziridinyl group (Q9), more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Most preferably, it is a group (Q1 to Q6). Similarly, the polymerizable group of the polymer of the alignment film is preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Is most preferred. M represents an atom or a group selected from the group consisting of a hydrogen atom, an alkali metal atom, and an ammonium group which may have a substituent. Considering that an alignment film can be formed with an aqueous solvent, R ¹ preferably represents —OM, and M preferably represents a group or an atom other than a hydrogen atom. The polymer may have two or more polymerizable groups.

Examples of the aromatic ring include a benzene ring, an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring,
Includes biphenylene, naphthacene, triphenylene and pyrene rings. The aromatic ring is preferably a benzene ring, and particularly preferably a tolan group in which two benzene rings are bonded by ethynylene. The heterocyclic ring preferably contains the most double bonds. Examples of the heterocycle include a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazane ring, a pyran ring, a pyridine ring, a pyridazine ring, and a pyrimidine ring. And a pyrazine ring. The heterocyclic ring is preferably a pyran ring. The aliphatic ring is preferably a saturated aliphatic ring. Examples of saturated aliphatic rings include:
Cyclobutane, cyclopentane, cyclohexane and cycloheptane rings are included. The saturated aliphatic ring is preferably a cyclohexane ring. The alkylene group may have a branched or cyclic structure. The number of carbon atoms of the alkylene group is preferably 1 to 30, more preferably 1 to 20,
It is more preferably 1 to 15, and most preferably 1 to 12. The alkenylene group may have a branched or cyclic structure. The number of carbon atoms of the alkylene group is preferably 1 to 20, more preferably 1 to 15, further preferably 1 to 10, and most preferably 1 to 6. The alkynylene group may have a branched or cyclic structure. The number of carbon atoms in the alkylene group is 1 to 2
It is preferably 0, more preferably 1 to 15, further preferably 1 to 10, and 1
It is most preferably from 6 to 6. The arylene group is preferably phenylene or naphthylene, more preferably phenylene, and most preferably p-phenylene. The arylene group may have a substituent. As the alkali metal atom,
Preferably it is sodium or potassium. The ammonium group which may have a substituent includes N
_{H (C 2 H 5) 3} , NH (CH 2 CHOHCH 3) 3, NH 3
_{C 2 H 5, NH 3 (} n-C 3 H 7), NH 3 (n-C 4 H 9),
NH ₂ (C ₂ HOH) ₂ , NH ₂ (C ₂ H ₅ ) ₂ , NH ₂ (i
_{-C 3 H 7) 2, NH} 2 (n-C 3 H 7) 2, NH 2 CH
_{3 (n-C 4 H 9} ) , NH ₂ (CH ₃ ) ₂ , NH ₂ (n-C _{4
H 9) 2, NHC 2 H} 5 (i-C 3 H 7) and NHCH
₃ (nC ₄ H ₉ ) ₂ .

The hydrocarbon group is an aliphatic group, an aromatic group or a combination thereof. The aliphatic group may be cyclic, branched, or linear. The aliphatic group is preferably an alkyl group (may be a cycloalkyl group) or an alkenyl group (may be a cycloalkenyl group). The hydrocarbon group may have a substituent that does not show strong hydrophilicity, such as a halogen atom. The number of carbon atoms in the hydrocarbon group is preferably 10 to 100, more preferably 10 to 60, and more preferably 10 to 60.
Most preferably, it is from 40 to 40. The hydrocarbon group preferably has a steroid structure. The steroid structure corresponds to a hydrocarbon group having 10 to 100 carbon atoms and has a function of vertically aligning discotic liquid crystal molecules. In the present specification, a steroid structure refers to a cyclopentanohydrophenanthrene ring structure or a ring structure in which a part of the bond of the ring is a double bond in the range of an aliphatic ring (range in which an aromatic ring is not formed). means. Further, the hydrocarbon group preferably has a fluorine-substituted hydrocarbon group.

Specific examples of a polyamic acid or a polyamic acid salt containing, as a repeating unit, a partial condensate of a tetracarboxylic acid having a polymerizable group and a diamine are described as follows. The repeating unit derived from a tetracarboxylic acid having a polymerizable group (I) will be described below, and the repeating unit derived from a diamine will be described later. Tetracarboxylic acid and Y
Is represented by using X and Y in the general formula (I), respectively, as the main skeleton of the structure. The following example is when it is substituted by the two carboxylic groups are both -L ⁰ -Q.

[0044]

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[0045]

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[0046]

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[0047]

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[0048]

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The degree of polymerization of the polyamic acid or polyamic acid salt is preferably from 200 to 5,000, more preferably from 300 to 3,000. The molecular weight of the polyamic acid or polyamic acid salt is 9
000 to 200,000, preferably 130
It is particularly preferred that it is from 00 to 130,000. Two or more kinds of polyamic acids or polyamic acid salts may be used in combination. Here, the polyamic acid and the polyamic acid salt can be obtained as follows. The polyamic acid is synthesized by a partial condensation reaction between a tetracarboxylic acid and a diamine. That is, two of the four carboxylic acid groups of the tetracarboxylic acid are reacted with the diamine to form an amide bond. In addition, polyamic acid salt,
It is obtained by neutralizing the polyamic acid synthesized as described above with a base. As the base, an alkali metal hydroxide (eg, KOH, NaOH), ammonia, and an organic base are preferably used. As the organic base, an aliphatic amine is preferred. Polyimide forms an imide bond by reacting four carboxyl groups of a tetracarboxylic acid with a diamine.

The polyamic acid (or polyamic acid salt) is a repeating unit consisting of only a tetracarboxylic acid having a polymerizable group before the partial condensation of the tetracarboxylic acid and the diamine (actually, the tetracarboxylic acid source is repeated). As a unit), this may form a copolymer with the above-described polyamic acid (or polyamic acid salt). The above-described polyamic acid (or polyamic acid salt) may be converted to polyimide, and a copolymer may be formed with this. The above polyamic acid (or polyamic acid salt) used to form the copolymer
May be those having a polymerizable group introduced into at least one of two carboxyl groups, or those having no polymerizable group introduced into any of the two carboxyl groups.

The copolymer (PA) of a repeating unit derived from a tetracarboxylic acid having a polymerizable group and a partial condensate of a tetracarboxylic acid and a diamine is preferably represented by the following formula. (PA)-(PAA) x- (I) y- wherein PAA is a partial condensate of a tetracarboxylic acid and a diamine, and I is a tetracarboxylic acid-derived repetition having a polymerizable group described above. Is a unit. x is 5 to 99 mol% (preferably 3 to 95 mol%);
y is 1 to 95 mol% (preferably 1 to 70 mol%). Preferred repeating units (PAA) are represented by the following formula.

[0052]

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In the above formula, X and Y are each a general formula
It has the same meaning as X and Y described in (I). R ² and R ³ independently of each other have the same meaning as R ¹ in formula (I).

When a polymerizable group is introduced into any of the two carboxyl groups in the repeating unit (I) derived from tetracarboxylic acid, the partial condensate (PAA) of tetracarboxylic acid and diamine is , R ² or R ³ is preferably a condensate in which either one is -OM,
It is particularly preferred that R ² and R ³ are both condensates of —OM. Preferably, the copolymer is a copolymer of a polyamic acid salt. Therefore, M is preferably an alkali metal atom or an ammonium group which may have a substituent.

Specific examples of the partial condensate (PAA) of a tetracarboxylic acid and a diamine are divided into a repeating unit derived from a tetracarboxylic acid (the nitrogen atom of the imide structure is derived from a diamine) and a repeating unit derived from a diamine. Shown in order. First, examples of preferred repeating units derived from tetracarboxylic acid are shown below.

[0056]

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[0057]

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[0058]

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[0059]

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[0060]

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(A8) M: Na (A9) M: NH (C_TwoH_Five)_Three  (A10) M: NH (CH_TwoCHOHCH_Three)_Three  (A11) M: NH_ThreeC_TwoH_Five  (A12) M: NH_Threen-C_ThreeH₇  (A13) M: NH_Threen-C_FourH₉  (A14) M: NH_Two(C_TwoH_FourOH)_Two  (A15) M: NH_Two(C_TwoH_Five)_Two  (A16) M: NH_Two(I-C_ThreeH₇)_Two  (A17) M: NH_Two(N-C_ThreeH₇)_Two  (A18) M: NH_TwoCH_Threen-C_FourH₉  (A19) M: NH_Two(CH_Three)_Two  (A20) M: NH_Two(N-C_FourH₉)_Two  (A21) M: NHC_TwoH_Fivei-C_ThreeH₇  (A22) M: NHCH_Three(N-C_FourH₉)_Two

Examples of repeating units derived from a diamine are shown below.

[0063]

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[0064]

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[0065]

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[0066]

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[0067]

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[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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A group different from the repeating unit may be bonded to the terminal of the formula (PA). Examples of the terminal group are shown below.

[0074]

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[0075]

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Examples of the polyamic acid salt copolymer having a polymerizable group introduced into at least one of the carboxyl groups include a repeating unit (A) derived from tetracarboxylic acid, a repeating unit (B) derived from diamine, and a polymerizable group. Are shown with reference to the numbers of the repeating unit (I) and the terminal group (E) derived from a tetracarboxylic acid having the formula: The proportion of repeating units in the copolymer is mol%.

[0077] _{PA1 :-( A9-B1) 98 -} (I8) 2 - PA2 :-( A1-B1) 95 - (I1) 5 - PA3 :-( A1-B1) 90 - (A1-B2) 7 - (I1)
_{3 - PA4 :-( A2-B4)} 98 - (I2) 2 - PA5 :-( A3-B8) 98 - (I3) 2 - PA6 :-( A2-B11) 98.5 - (I2) 1.5 - PA7: - _{(A2-B11) 50 - (} A4-B21) 48 -
_{(I2) 2 - PA8 :-( A4} -B11) 96 - (I4) 4 - PA10 :-( A5-B13) 98.5 - (I5) 1.5 - PA11 :-( A6-B23) 97 - (I6) 3 - _{PA12 :-( A6-B23) 97 -} (I6) 3 - PA13 :-( A7-B1) 98 - (I7) 2 - PA14 :-( A7-B6) 98 - (I7) 2 - PA15 :-( A8 _{-B12) 98.5 - (I8) 1.5} - PA16 :-( A9-B19) 98 - (I8) 2 - PA17 :-( A10-B22) 98 - (I8) 2 - PA18 :-( A11-B25) 98.5 - _{(I8) 1.5 - PA19: E1-} (A4-B1) 97 - (I4) 3 -E4 PA20: E3- (A6-B21) 98 - (I6) 3 -E6

[0078] _{PA21 :-( A9-B1) 98 -} (I9) 2 - PA22 :-( A9-B1) 98 - (I10) 2 - PA23 :-( A9-B1) 98 - (I11) 2 - PA24: _{- (A9-B1) 98 -} (I12) 2 - PA25 :-( A9-B1) 98 - (I13) 2 - PA26 :-( A9-B1) 98 - (I14) 2 - PA27 :-( A9-B1 _{) 98 - (I15) 2 -} PA28 :-( A9-B1) 98 - (I16) 2 - PA29 :-( A9-B1) 98 - (I17) 2 -

The above-mentioned copolymer of a polyamic acid salt having a polymerizable group can be obtained by, for example, activating a carboxyl group by a known method, and combining the carboxyl group with an isocyanate compound, an alcohol compound, or a compound having a polymerizable group in the presence of a base. It can be easily synthesized by reacting with an amine compound or the like. Other known reactions can be used for the amide bond with the carboxyl group, the ester bond with the carboxyl group, and the like.

The polymer used for the liquid crystal alignment film may be crosslinked. The crosslinking reaction is preferably carried out simultaneously with or after the application of the coating liquid for the liquid crystal alignment film. Crosslinking of the polymer can be formed using a crosslinking agent. Examples of the crosslinking agent include epoxy compounds (eg, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, polyethylene glycol diglycidyl ether), aldehydes (eg, formaldehyde, glyoxal, glutaraldehyde, malonaldehyde, phthalaldehyde, terephthalaldehyde, Succinaldehyde, isophthalaldehyde, dialdehyde starch), N-methylol compound (eg, dimethylol urea, methylol dimethylhydantoin), dioxane (eg, 2,3-dihydroxy dioxane), carbenium, 2-naphthalate sulfonate, 1, 1-bispyrrolidino-1-chloropyridinium, 1-morpholinocarbonyl-3- (sulfonatoaminomethyl), active vinyl compound (eg, 1,3,5-tria Acryloyl - hexahydro -s- triazine, bis (vinylsulfone) methane, N, N'-methylenebis -
[Β- (vinylisulfonyl) propionamide), active halogen compounds (eg, 2,4-dichloro-6-hydroxy-s-triazine) and isoxazoles. When the polymer is polyimide or polyamic acid (or a salt thereof), it is preferable to use an epoxy compound as a crosslinking agent.

A liquid crystal alignment film can be formed by applying a coating solution of a polyamic acid (or a salt thereof) on a support. The thickness of the alignment film is 0.1 to 10 μm
It is preferable that In forming the alignment film, a rubbing treatment is preferably performed. The rubbing treatment is performed by rubbing the surface of the film containing the polyamic acid (or a salt thereof) several times in a certain direction with paper or cloth. After aligning the liquid crystal molecules substantially vertically using the alignment film, the liquid crystal molecules are fixed in the aligned state to form an optically anisotropic layer, and the optically anisotropic layer is transparently supported. It may be transcribed on the body. The liquid crystalline molecules fixed in the alignment state can maintain the alignment state without the alignment film. The alignment film of the present invention is particularly effective when used for discotic liquid crystal molecules.

[Liquid Crystal Layer] The liquid crystal molecules to be aligned by the alignment film form a liquid crystal layer. The above-mentioned alignment film has a function of aligning liquid crystal molecules substantially vertically at an average tilt angle in the range of 50 to 90 degrees. As the liquid crystal molecules, rod-shaped liquid crystal molecules or discotic liquid crystal molecules are preferable. The tilt angle of the rod-like liquid crystal molecules means the angle between the major axis direction of the rod-like liquid crystal molecules and the substrate plane, and the tilt angle of the discotic liquid crystal molecules is the angle between the discotic liquid crystal molecules and the substrate plane. Means When the liquid crystal element is used as a liquid crystal cell, it is particularly preferable to use rod-like liquid crystal molecules. Azomethines, as rod-like liquid crystal molecules,
Azoxys, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxane, tolanes and alkenylcyclohexyl Benzonitrile is preferably used. As a liquid crystal cell in which rod-like liquid crystal molecules are substantially vertically aligned, VA (Vertically Alignment) is used.
An ed) mode liquid crystal cell is typical. For a liquid crystal display device using a VA mode liquid crystal cell, see Nikkei Micro Device No. 136, 147 (1996), JP-A-2-176625 and Patent No. 286637.
It is described in Japanese Patent Publication No.

[Optical Anisotropic Layer] The optically anisotropic layer contains discotic liquid crystal molecules. In the optically anisotropic layer,
Using the above-mentioned alignment film, the disc surface of the discotic liquid crystalline molecules is substantially perpendicular to the alignment film (50 to 9).
(An average inclination angle in a range of 0 degree). It is preferable that the discotic liquid crystal molecules are fixed in the optically anisotropic layer while maintaining a vertical (homogeneous) alignment state. More preferably, the discotic liquid crystalline molecules are fixed by a polymerization reaction. Discotic liquid crystal molecules are described in various literatures (C. Destrade et al., Mol. Crysr. Liq. Cry
st., vol. 71, page 111 (1981); edited by The Chemical Society of Japan, quarterly chemistry review, No. 22, Chemistry of Liquid Crystal, Chapter 5, Chapter 10, Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. C
hem. Comm., page 1794 (1985); J. Zhang et al., J.
Am. Chem. Soc., Vol. 116, page 2655 (1994)). The polymerization of discotic liquid crystal molecules is described in JP-A-8-27284. In order to fix discotic liquid crystalline molecules by polymerization,
It is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecule. However, when a polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain an oriented state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Therefore, the discotic liquid crystalline molecule having a polymerizable group is preferably a compound represented by the following formula.

D (-LQ)_n  Wherein D is a discotic core; L is a divalent linking group
Q is a polymerizable group; and n is an integer of 4 to 12.
Is a number. An example of the discotic core (D) of the above formula is shown below.
You. In each of the following examples, LQ (or QL)
Means a combination of a linking group (L) and a polymerizable group (Q)
I do.

[0085]

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[0086]

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[0087]

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[0088]

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[0089]

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[0090]

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[0091]

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[0092]

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In the above formula, the divalent linking group (L) is
Alkylene group, alkenylene group, arylene group, -CO
It is preferably a divalent linking group selected from the group consisting of-, -NH-, -O-, -S- and a combination thereof. The divalent linking group (L) is an alkylene group, an alkenylene group, an arylene group, -CO-, -NH-, -O-
And a group obtained by combining at least two divalent groups selected from the group consisting of and -S-.
The divalent linking group (L) is most preferably a group obtained by combining at least two divalent groups selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, -CO- and -O-. The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The arylene group preferably has 6 to 10 carbon atoms. The alkylene group, alkenylene group and arylene group may have a substituent (eg, an alkyl group, a halogen atom, a cyano, an alkoxy group, an acyloxy group). 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 bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene 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-AL-AR-O-AL-O-CO-L17: -O-CO-AR-O-AL-CO-L18: -O-CO-AR-O-AL-O-CO-L19: -O-CO-AR-O-AL-O-AL-OC
O-L20: -O-CO-AR-O-AL-O-AL-OA
L-O-CO-L21: -S-AL-L22: -S-AL-O-L23: -S-AL-O-CO-L24: -S-AL-S-AL-L25: -S-AR -AL-

When an asymmetric carbon atom is introduced into AL (alkylene group or alkenylene group), the discotic liquid crystal molecule can be twisted in a helical manner.
Examples of AL * containing an asymmetric carbon atom are given below. The left side is the disc-shaped core (D) side, and the right side is the polymerizable group (Q) side. The carbon atom (C) marked with * is an asymmetric carbon atom. The optical activity may be either S or R.

AL * 1: —CH ₂ CH ₂ —C * HCH ₃ —CH ₂ CH
_{2 CH 2 - AL * 2:} -CH 2 CH 2 CH 2 -C * HCH 3 -CH
_{2 CH 2 - AL * 3:} -CH 2 -C * HCH 3 -CH 2 CH 2 CH
_{2 CH 2 - AL * 4:} -C * HCH 3 -CH 2 CH 2 CH 2 CH 2
_{CH 2 - AL * 5: -CH} 2 CH 2 CH 2 CH 2 -C * HCH 3
_{-CH 2 - AL * 6: -CH} 2 CH 2 CH 2 CH 2 CH 2 -C * H
_{CH 3 - AL * 7: -C} * HCH 3 -CH 2 CH 2 CH 2 CH 2
_{- AL * 8: -CH 2 -C} * HCH 3 -CH 2 CH 2 CH
_{2 - AL * 9: -CH 2} CH 2 -C * HCH 3 -CH 2 CH
_{2 - AL * 10: -CH 2} CH 2 CH 2 -C * HCH 3 -CH
_{2 - AL * 11: -CH 2} CH 2 CH 2 CH 2 -C * HCH 3
- AL * 12: -C * HCH 3 -CH 2 CH 2 CH 2 - AL * 13: -CH 2 -C * HCH 3 -CH 2 CH 2 - AL * 14: -CH 2 CH 2 -C * HCH 3 _{-CH 2 - AL * 15: -CH} 2 CH 2 CH 2 -C * HCH 3 -

AL * 16: -CH ₂ -C * HCH ₃ -AL * 17: -C * HCH ₃ -CH ₂ -AL * 18: -C * HCH ₃ -CH ₂ CH ₂ CH ₂ CH _{2
CH 2 CH 2 - AL * 19} : -CH 2 -C * HCH 3 -CH 2 CH 2 CH
_{2 CH 2 CH 2 - AL *} 20: -CH 2 CH 2 -C * HCH 3 -CH 2 CH
_{2 CH 2 CH 2 - AL *} 21: -CH 2 CH 2 CH 2 -C * HCH 3 -CH
_{2 CH 2 CH 2 - AL *} 22: -C * HCH 3 -CH 2 CH 2 CH 2 CH 2
_{CH 2 CH 2 CH 2 - AL} * 23: -CH 2 -C * HCH 3 -CH 2 CH 2 CH
₂ CH ₂ CH ₂ CH ₂ -AL * 24: -CH ₂ CH ₂ -C * HCH ₃ -CH ₂ CH
_{2 CH 2 CH 2 CH 2 -} AL * 25: -CH 2 CH 2 CH 2 -C * HCH 3 -CH
_{2 CH 2 CH 2 CH 2 -} AL * 26: -C * HCH 3 - (CH 2) 8 - AL * 27: -CH 2 -C * HCH 3 - (CH 2) 8 - AL * 28: -CH 2 _{-C * HCH 2 CH 3 - AL} * 29: -CH 2 -C * HCH 2 CH 3 -CH 2 - AL * 30: -CH 2 -C * HCH 2 CH 3 -CH 2 CH
₂ −

AL * 31: —CH ₂ —C * HCH ₂ CH ₃ —CH ₂ CH
_{2 CH 2 CH 2 - AL *} 32: -CH 2 -C * H (n-C 3 H 7) -CH 2
_{CH 2 - AL * 33: -CH} 2 -C * H (n-C 3 H 7) -CH 2
_{CH 2 CH 2 CH 2 - AL} * 34: -CH 2 -C * H (OCOCH 3) -CH 2
_{CH 2 - AL * 35: -CH} 2 -C * H (OCOCH 3) -CH 2
_{CH 2 CH 2 CH 2 - AL} * 36: -CH 2 -C * HF-CH 2 CH 2 - AL * 37: -CH 2 -C * HF-CH 2 CH 2 CH 2 C
_{H 2 - AL * 38: -CH} 2 -C * HCl-CH 2 CH 2 - AL * 39: -CH 2 -C * HCl-CH 2 CH 2 CH 2
_{CH 2 - AL * 40: -CH} 2 -C * HOCH 3 -CH 2 CH 2 - AL * 41: -CH 2 -C * HOCH 3 -CH 2 CH 2 C
_{H 2 CH 2 - AL * 42} : -CH 2 -C * HCN-CH 2 CH 2 - AL * 43: -CH 2 -C * HCN-CH 2 CH 2 CH 2
_{CH 2 - AL * 44: -CH} 2 -C * HCF 3 -CH 2 CH 2 - AL * 45: -CH 2 -C * HCF 3 -CH 2 CH 2 CH
₂ CH ₂ −

The polymerizable group (Q) in the above formula is determined according to the type of the polymerization reaction. Examples of the polymerizable group (Q) are shown below.

[0101]

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The polymerizable group (Q) is an unsaturated polymerizable group (Q1
To Q7), an epoxy group (Q8) or an aziridinyl group (Q9), more preferably an unsaturated polymerizable group, and more preferably an ethylenically unsaturated polymerizable group (Q
1 to Q6) are most preferred. In the above formula, n is an integer of 4 to 12. The specific numbers are
It is determined according to the type of discotic core (D). The combination of a plurality of L and Q may be different, but is preferably the same. Two or more discotic liquid crystal molecules may be used in combination. For example, a molecule having an asymmetric carbon atom in the divalent linking group and a molecule having no asymmetric carbon atom can be used in combination. Further, a molecule having a polymerizable group (Q) and a molecule having no polymerizable group (Q) may be used in combination. It is particularly preferable to use a molecule having an asymmetric carbon atom and having no polymerizable group in combination with a molecule having a polymerizable group and having no asymmetric carbon atom. In this case, only molecules having a polymerizable group and having no asymmetric carbon atom function as discotic liquid crystal molecules, and molecules having an asymmetric carbon atom and having no polymerizable group are chiral agents. (Described later).

The non-polymerizable discotic liquid crystalline molecules are
Polymerizable group of the above-mentioned polymerizable discotic liquid crystalline molecule
Compound in which (Q) is changed to a hydrogen atom or an alkyl group
It is preferred that That is, non-polymerizable discotheque
Is a compound represented by the following formula:
Is preferred. D (-LR)_n  Wherein D is a discotic core; L is a divalent linking group
R is a hydrogen atom or an alkyl group;
Is an integer of 4 to 12. Disc-shaped core of the above formula (D)
Is an example of changing LQ (or QL) to LR (or RL).
Except for further modifications, the polymerizable discotic liquid crystal molecules described above
Is the same as in the example. Examples of the divalent linking group (L) also include
The same as the example of the polymerizable discotic liquid crystal molecules described above.
You. The alkyl group for R has 1 to 40 carbon atoms
And more preferably 1 to 30.
No. Chain alkyl groups are preferred over cyclic alkyl groups
Straight chain alkyl rather than branched chain alkyl group
Groups are preferred. R represents a hydrogen atom or a carbon atom number;
Particularly preferred is a linear alkyl group of 1 to 30.
No.

Instead of introducing an asymmetric carbon atom into the divalent linking group (L) of the discotic liquid crystal molecule, a compound having an asymmetric carbon atom and exhibiting optical activity (chiral agent) is used as an optically anisotropic layer. , The discotic liquid crystalline molecules can be helically twisted and aligned. As the compound containing an asymmetric carbon atom, various natural or synthetic compounds can be used. The same or similar polymerizable group as the discotic liquid crystalline molecule may be introduced into the compound containing an asymmetric carbon atom. When a polymerizable group is introduced, the discotic liquid crystal molecules are aligned substantially vertically (homogeneously) and then fixed, and at the same time, the compound containing an asymmetric carbon atom is also optically anisotropic by the same or similar polymerization reaction. Can be fixed in the functional layer.

A fluorine-containing surfactant or a cellulose ester can be added to the optically anisotropic layer in order to align the discotic liquid crystal molecules substantially vertically (homogeneously) and uniformly on the air interface side. . The fluorinated surfactant is composed of a hydrophobic group containing a fluorine atom, a nonionic, anionic, cationic or amphoteric hydrophilic group and an optionally provided linking group. Fluorine-containing surfactant consisting of one hydrophobic group and one hydrophilic group,
It is represented by the following equation. Rf-L ⁵ -Hy In the formula, Rf is a monovalent hydrocarbon group substituted with a fluorine atom, L ⁵ is a single bond or a divalent linking group,
Hy is a hydrophilic group. The above Rf functions as a hydrophobic group. The hydrocarbon group is preferably an alkyl group or an aryl group. The alkyl group preferably has 3 to 30 carbon atoms, and the aryl group preferably has 6 to 30 carbon atoms. Some or all of the hydrogen atoms contained in the hydrocarbon group are substituted with fluorine atoms. It is preferable to replace 50% or more of the hydrogen atoms contained in the hydrocarbon group with a fluorine atom.
More preferably, 0% or more is substituted, more preferably 70% or more is substituted, and most preferably 80% or more is substituted. The remaining hydrogen atoms may be further substituted with another halogen atom (eg, chlorine atom, bromine atom). Examples of Rf are shown below.

Rf1: nC ₈ F ₁₇ -Rf2: nC ₆ F ₁₃ -Rf3: Cl— (CF ₂ —CFCl) ₃ —CF ₂ —Rf 4: H— (CF ₂ ) ₈ —Rf5: H— _{(CF 2) 10 - Rf6:} n-C 9 F 19 - Rf7: pentafluorophenyl _{Rf8: n-C 7 F 15} - Rf9: Cl- (CF 2 -CFCl) 2 -CF 2 - Rf10: H- (CF _{2) 4 - Rf11: H- (} CF 2) 6 - Rf12: Cl- (CF 2) 6 - Rf13: C 3 F 7 -

In the above formula, the divalent linking group is an alkylene group, an arylene group, a divalent heterocyclic residue, -CO
—, —NR— (R is an alkyl group having 1 to 5 carbon atoms or a hydrogen atom), —O—, —SO ₂ — and a divalent linking group selected from the combination thereof. preferable. Examples of L ⁵ in the formula shown below. The left side is bonded to a hydrophobic group (Rf), and the right side is a hydrophilic group (Hy).
To join. AL represents an alkylene group, AR represents an arylene group, and Hc represents a divalent heterocyclic residue. Incidentally, an alkylene group, an arylene group and a divalent heterocyclic residue are
It may have a substituent (eg, an alkyl group).

[0108] L0: single bond _{L51: -SO 2 -NR- L52: -AL} -O- L53: -CO-NR- L54: -AR-O- L55: -SO 2 -NR-AL-CO-O- L56: -CO-O- L57: -SO 2 -NR-AL-O- L58: -SO 2 -NR-AL- L59: -CO-NR-AL- L60: -AL-O-AL- L61: - _{hc-AL- L62: -SO 2 -NR} -AL-O-AL- L63: -AR- L64: -O-AR-SO 2 -NR-AL- L65: -O-AR-SO 2 -NR- L66 : -O-AR-O-

Hy in the above formula is any one of a nonionic hydrophilic group, an anionic hydrophilic group, a cationic hydrophilic group and an amphoteric hydrophilic group. Nonionic hydrophilic groups are particularly preferred. An example of Hy in the above formula is shown below.

Hy1:-(CH_Two CH_Two O)_n -H (n is 5 to 30)
Hy2:-(CH_Two CH_Two O)_n -R¹ (N is 5 to 3
An integer of 0, R¹ Is an alkyl group having 1 to 6 carbon atoms) Hy3:-(CH_Two CHOHCH_Two )_n -H (n is 5no
Hy4: -COOM (M is a hydrogen atom, an alkali metal atom)
Hy5: -SO_Three M (M is a hydrogen atom, an alkali metal atom
Or dissociated state) Hy6:-(CH_Two CH_Two O)_n -CH_Two CH_Two CH_Two 
-SO_Three M (n is an integer of 5 to 30, M is a hydrogen atom or
Is an alkali metal atom) Hy7: -OPO (OH)_Two  Hy8: -N⁺ (CH_Three )_Three ・ X^- (X is halogen source
Child) Hy9: -COONH_Four

Nonionic hydrophilic groups (Hy1, Hy2, H
y3) is preferable, and a hydrophilic group (Hy1) composed of polyethylene oxide is most preferable. A fluorine-containing surfactant having two or more hydrophobic or hydrophilic groups containing a fluorine atom may be used. Two or more fluorine-containing surfactants may be used in combination. For fluorinated surfactants, see various references (eg, Hiroshi Horiguchi, “New Surfactants”, Sankyo Publishing (197
5), MJ Schick, Nonionic Surfactants, Marcell Dek
ker Inc., New York, (1967), JP-A-7-13293). The amount of the fluorinated surfactant is preferably in the range of 0.01 to 30% by weight, more preferably 0.05 to 10% by weight, and more preferably 0.1 to 5% by weight of the amount of the discotic liquid crystal molecules. % Is more preferable.

As the cellulose ester, a lower fatty acid ester of cellulose is preferably used. The “lower fatty acid” in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is preferably 2 to 5, more preferably 2 to 4. A substituent (eg, hydroxy) may be bonded to the fatty acid. Two or more fatty acids may form an ester with cellulose. Examples of lower fatty acid esters of cellulose include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose hydroxypropionate, cellulose acetate propionate, and cellulose acetate butyrate. Cellulose acetate butyrate is particularly preferred. The butyrylation degree of cellulose acetate butyrate is preferably 30% or more, and preferably 3% or more.
More preferably, it is 0 to 80%. The acetylation degree of cellulose acetate butyrate is preferably 30% or less, more preferably 1 to 30%. Cellulose ester is used in an amount of 0.005 to 0.5.
Preferably, it is used in an amount in the range of 5 g / m ² ,
The range is more preferably from 0.01 to 0.45 g / m ² , still more preferably from 0.02 to 0.4 / m ² , and more preferably from 0.03 to 0.35 / m ^2. Is most preferred. It is also preferable to use 0.1 to 5% by weight of the discotic liquid crystal molecules.

The optically anisotropic layer is composed of a discotic liquid crystal molecule, a compound containing an asymmetric carbon atom, if necessary, a fluorinated surfactant, a cellulose ester, or the following polymerization initiators and other additives. Is formed by applying a coating solution containing As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of the organic solvent include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethylsulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, ,
Chloroform, dichloromethane), ester (eg, methyl acetate, butyl acetate), ketone (eg, acetone, methyl ethyl ketone), ether (eg, tetrahydrofuran,
1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

The coating solution can be applied by a known method (eg, extrusion coating, direct gravure coating, reverse gravure coating, die coating, bar coating). Discotic liquid crystalline molecules that are substantially vertically (homogeneously) aligned are fixed while maintaining the alignment state. Immobilization is
Polymerizable group (Q) introduced into discotic liquid crystal molecules
It is preferable to carry out the polymerization reaction. 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 photopolymerization initiators include α-carbonyl compounds (described in U.S. Pat. Nos. 2,367,661 and 2,367,670) and acyloin ethers (U.S. Pat.
No. 8), α-hydrocarbon substituted aromatic acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (US Pat. Nos. 3,046,127 and 2951).
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-60-105667, US Pat. No. 4,239,850). Oxadiazole compounds (described in US Pat. No. 4,221,970).

The amount of the photopolymerization initiator used is preferably from 0.01 to 20% by weight of the solid content of the coating solution.
More preferably, it is 5 to 5% by weight. Light irradiation for the polymerization of discotic liquid crystalline molecules preferably uses ultraviolet light. The irradiation energy is 20 mJ /
cm ^{2 to} 50 J / cm ² , preferably 10
More preferably, it is 0 to 2000 mJ / cm ² . Light irradiation may be performed under heating conditions to promote the photopolymerization reaction. The thickness of the optically anisotropic layer is preferably 0.1 to 50 μm, more preferably 1 to 30 μm, and most preferably 5 to 20 μm. When two optical compensatory sheets are used in the liquid crystal display device, the thickness may be half the thickness of the optically anisotropic layer (the above-mentioned preferred range) required when using one optical compensatory sheet. The average tilt angle of the discotic liquid crystalline molecules in the optically anisotropic layer is 50 to 90 degrees. The angle of inclination is preferably as uniform as possible. However, if the tilt angle changes continuously along the thickness direction of the optically anisotropic layer, there is no problem even if there is a slight change.

The twist angle of the discotic liquid crystal molecules (twist angle) is similar (preferably 180 to 360 degrees, preferably more than 180 degrees to 270 degrees) according to the twist angle of the STN type liquid crystal cell. It is preferable to adjust the angle to be within ± 10 degrees. When one optical compensation sheet is used for a liquid crystal display device, the twist angle of the discotic liquid crystal molecules is 180 to 36.
It is preferable that the angle is in the range of 0 degrees. When two optical compensation sheets are used in a liquid crystal display device, the twist angle of the discotic liquid crystal molecules is preferably in the range of 90 to 180 degrees. When the optical compensation sheet is used in an STN-type liquid crystal display device, the wavelength dependence (Δn (λ)) of the birefringence of the optically anisotropic layer depends on the wavelength dependence of the birefringence of the liquid crystal of the STN type liquid crystal cell. Preferably, the values are close.

[Liquid Crystal Display Device] As described above, the present invention is particularly effective in a liquid crystal display device using an STN type liquid crystal cell. The STN type liquid crystal display device includes an STN type liquid crystal cell, one or two optical compensatory sheets disposed on one or both sides of the liquid crystal cell, and a pair of polarizing plates disposed on both sides thereof. The relationship between the alignment direction of the rod-like liquid crystal molecules in the liquid crystal cell and the alignment direction of the discotic liquid crystal molecules is determined by the director of the liquid crystal cell closest to the optical compensation sheet (the long axis direction of the rod-like molecules) and the liquid crystal. The director of the discotic liquid crystalline molecules of the optical compensation sheet closest to the cell (the normal direction of the disk-shaped core plane)
Seen from the normal direction of the liquid crystal cell, substantially the same direction (± 1
(Less than 0 degrees). The transparent support of the optical compensation sheet can also function as a protective film on the liquid crystal cell side of the polarizing film. In this case, the transparent support should be arranged so that the slow axis (the direction in which the refractive index is maximized) and the transmission axis of the polarizing film are substantially perpendicular or substantially parallel (less than ± 10 degrees). Is preferred.

[0118]

[Example 1] (Preparation of polyamic acid salt) An aqueous solution of a polyamic acid salt (PA1) represented by the following formula was mixed with 1 g of the corresponding polyamic acid (carboxylic acid amount: 2.71 mg equivalent). 1N
It was prepared by dissolving in 50 mL of an aqueous triethyleneamine solution.

[0119]

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(Preparation of Alignment Film) A 100 μm thick, 270 mm × 100 mm triacetyl cellulose film (Fujitac, manufactured by Fuji Photo Film Co., Ltd.) was used as a transparent support. The aqueous solution of the polyamic acid salt (PA1) prepared above was applied to a thickness of 1 μm on a transparent support using a bar coater.

The coating layer was dried with hot air at 80 ° C. for 10 minutes, and further heated at 120 ° C. for 30 minutes. The surface was rubbed to form an alignment film. On the alignment film, a coating solution having the following composition was applied by an extrusion method.

(Preparation of Optical Compensation Sheet) On the alignment film,
A coating solution having the following composition was applied using a spin coater at 1000 rpm, and dried at room temperature.

<< Coating Liquid for Optically Anisotropic Layer >>デ ィ ス The following discotic liquid crystalline compound (1) 91 parts by weight The following chiral agent (1) 1.6 parts by weight Cellulose acetate butyrate having a degree of acetylation of 2.0%, a degree of butyrylation of 52.0%, and a number average molecular weight of 30,000 (CAB-551-0.2, manufactured by Eastman Chemical Company) 0 .25 parts by weight Cellulose acetate butyrate having a degree of acetylation of 3.0%, a degree of butyrylation of 50.0%, and a number average molecular weight of 40,000 (CAB-531-1, manufactured by Eastman Chemical Company) 0.25 parts by weight Ethylene oxide modified Trimethylolpropane triacrylate (V # 3 60, manufactured by Osaka Organic Chemical Co., Ltd.) 9 parts by weight Photopolymerization initiator (Irgacure 907, manufactured by Nippon Ciba Geigy) 3 parts by weight Sensitizer (Kayacure-DETX, manufactured by Nippon Kayaku) 1 weight Parts methyl ethyl ketone 120 parts by weight ────────────────────────────────────

[0124]

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[0125]

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The coating layer was heated at 130 ° C. for 2 minutes to orient the discotic liquid crystal compound substantially vertically. At that temperature, ultraviolet rays were irradiated for 4 seconds to polymerize the discotic liquid crystalline compound and fix the alignment state. In this manner, an optically anisotropic layer in which the discotic liquid crystalline compound was vertically and twisted was formed, and an optical compensation sheet was produced. Δn of the obtained optical compensation sheet
When d was measured at a wavelength of 550 nm, 440n
m. The twist angle of the discotic liquid crystal compound was 120 degrees. When a cellophane tape was attached to the optically anisotropic layer and the tape was pulled in parallel with the optically anisotropic layer and peeled off, no layer was adhered to the surface of the peeled tape.

Separately, except that the discotic liquid crystal compound (1) was removed from the coating liquid for the optically anisotropic layer, the discotic liquid crystal compound was substantially vertically oriented, but twisted. No optical compensatory sheet made. For this sheet, using an ellipsometer,
The in-plane retardation (Re) was measured, and the average inclination angle with respect to the support surface was determined from the angle dependence.
It was 85 degrees.

Example 2 An optical compensatory sheet was prepared and evaluated in the same manner as in Example 1 except that a coating liquid for an optically anisotropic layer having the following composition was used.

<< Coating Liquid for Optically Anisotropic Layer >>デ ィ ス The following discotic liquid crystalline compound (2) 91 parts by weight The following chiral agent (2) 2.0 parts by weight cellulose acetate butyrate having a degree of acetylation of 2.0%, a degree of butyrylation of 52.0% and a number average molecular weight of 30,000 (CAB-551-0.2, manufactured by Eastman Chemical Company) .25 parts by weight Cellulose acetate butyrate having a degree of acetylation of 3.0%, a degree of butyrylation of 50.0%, and a number average molecular weight of 40,000 (CAB-531-1, manufactured by Eastman Chemical Company) 0.25 parts by weight Ethylene oxide modified Trimethylolpropane triacrylate (V # 3 60, manufactured by Osaka Organic Chemical Co., Ltd.) 9 parts by weight Photopolymerization initiator (Irgacure 369, manufactured by Nippon Ciba Geigy Co., Ltd.) 3 parts by weight Methyl ethyl ketone 120 parts by weight ──────────────────────

[0130]

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[0131]

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The Δnd of the obtained optical compensation sheet was set to a wavelength of 5
It was 880 nm when measured at 50 nm. The twist angle of the discotic liquid crystalline compound was 240 degrees. Furthermore, when the alignment state of the discotic liquid crystalline molecules was confirmed with a polarizing microscope, all the molecules were uniformly aligned (monodomain alignment).

[Example 3] (Production of STN type liquid crystal display device) Twist angle was 240
Under the STN liquid crystal cell having an １nd of 880 nm, one optical compensation sheet prepared in Example 2 and the optically anisotropic layer were faced to each other. Lamination was performed so that the directors of the molecules (the normal direction of the disc surface of the discotic liquid crystalline molecules) coincided. The optical compensation sheet was attached to the liquid crystal cell such that the discotic liquid crystal molecules and the director of the rod-like liquid crystal molecules of the liquid crystal cell coincided on the surface where the optical compensation sheet and the liquid crystal cell were bonded. Further, a pair of polarizing plates were attached in a crossed Nicol arrangement to produce an STN liquid crystal display device. When the manufactured STN liquid crystal display device was compared with the STN liquid crystal display device without the optical compensation sheet, a remarkable effect of improving the viewing angle by the optical compensation sheet was recognized.

[Example 4] Polyamic acid salt (PA1)
Is replaced by a polyamic acid salt represented by the following formula (PA1
An optical compensatory sheet was prepared and evaluated in the same manner as in Example 1, except that the same amount of 5) was used. The average tilt angle of the discotic liquid crystal molecules was 80 degrees.

[0135]

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When a cellophane tape was attached to the optically anisotropic layer and the tape was pulled in parallel with the optically anisotropic layer and peeled off, no layer was adhered to the surface of the peeled tape. Was.

[Example 5] Polyamic acid salt (PA1)
Is replaced by a polyamic acid salt represented by the following formula (PA2
An optical compensatory sheet was prepared and evaluated in the same manner as in Example 1 except that 2) was used in the same amount. The average tilt angle of the discotic liquid crystalline molecules was 85 degrees.

[0138]

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When a cellophane tape was attached to the optically anisotropic layer and the tape was pulled in parallel with the optically anisotropic layer and peeled off, no layer was adhered to the surface of the peeled tape. Was.

[Brief description of the drawings]

FIG. 1 shows the alignment state of rod-like liquid crystal molecules in a liquid crystal cell and the alignment state of discotic liquid crystal molecules in an optically anisotropic layer in a pixel portion of a STN type liquid crystal display device where no voltage is applied (off). It is sectional drawing which shows typically.

FIG. 2 is a schematic diagram showing respective refractive index ellipsoids of rod-like liquid crystal molecules of a liquid crystal cell and discotic liquid crystal molecules of an optical compensation sheet which has a relation of optically compensating the rod-like liquid crystal molecules.

FIG. 3 is a schematic view illustrating a layer configuration of an STN liquid crystal display device.

FIG. 4 is a plan view showing preferred optical directions for each element of the STN liquid crystal display device.

FIG. 5 is a plan view showing another preferred optical direction for each element of the STN type liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Liquid crystal cell 2, 2a, 2b Optical compensation sheet 3, 3a, 3b Polarizer 11 Upper substrate of a liquid crystal cell 12, 14 Alignment film of a liquid crystal cell 13 Refractive index ellipsoid of a rod-like liquid crystal molecule 13a-13e Rod-like liquid crystal molecule 13t Thickness of rod-like liquid crystalline molecule layer 13x, 13y Refractive index of rod-like liquid crystalline molecule in plane parallel to alignment film 13z Refractive index of rod-like liquid crystalline molecule in thickness direction 15 Lower substrate of liquid crystal cell 21 Refraction of discotic liquid crystalline molecule Index ellipsoids 21a to 21e Discotic liquid crystal molecules 21t Thickness of discotic liquid crystal molecule layer 21x, 21y Refractive index in a plane parallel to the alignment film of discotic liquid crystal molecules 21z Refraction in the thickness direction of discotic liquid crystal molecules Ratio 22 Alignment film 23 Transparent support BL Backlight DDa, DDb, DDc, DDd Discotic liquid crystal Normal direction RDa of the disc face of the child, the direction the rubbing direction TAa, the transmission axis X criteria TAb polarizing plate alignment film RDb liquid crystal cell

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G02F 1/1337 520 G02F 1/1337 520 4J043 F-term (Reference) 2H049 BA06 BA42 BC02 BC22 2H090 HB09Y HB10Y HB13Y LA06 MA01 MA11 MB01 2H091 FA11X FA11Z FB02 FC23 FD10 GA06 HA10 KA03 LA12 4F100 AH10C AJ06 AK80B AK80K AR00B AR00C AT00A BA03 BA07 BA10A BA10C EH46 GB41 JL11 JN01A JN10 4J002 CM041 GP00 GQ0B01 PC01 PC00 UA132 UA151 UA232 UA262 UB021 UB131 UB161 UB162 UB211 UB281 ZA09 ZB23

Claims (6)

[Claims] 1. A liquid crystal alignment film provided on a transparent support, wherein the liquid crystal alignment film contains a polymer having a repeating unit represented by the following formula: ] [Wherein, X represents a tetravalent group containing an aromatic ring, an aliphatic ring or a heterocyclic ring; Y represents a divalent group containing an aromatic ring; provided that at least one of X and Y One has a hydrocarbon group having 10 to 100 carbon atoms as a substituent; L ⁰ is a single bond, -O-, -CO-, -S-, -S
Q represents a divalent linking group selected from the group consisting of O ₂ —, —NH—, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a combination thereof;
Represents a polymerizable group; R ¹ represents -L ⁰ -Q or -OM; M is selected from the group consisting of a hydrogen atom, an alkali metal atom, and an optionally substituted ammonium group. Represents an atom or group that is 2. The method according to claim 1, wherein the hydrocarbon group having 10 to 100 carbon atoms has a steroid group.
The liquid crystal alignment film according to 1. 3. An optical compensation sheet having a liquid crystal alignment film and an optically anisotropic layer formed of discotic liquid crystal molecules on a transparent support in this order, wherein the liquid crystal alignment film has the following formula: 2] [Wherein, X represents a tetravalent group containing an aromatic ring, an aliphatic ring or a heterocyclic ring; Y represents a divalent group containing an aromatic ring; provided that at least one of X and Y One has a hydrocarbon group having 10 to 100 carbon atoms as a substituent; L ⁰ is a single bond, -O-, -CO-, -S-, -S
Q represents a divalent linking group selected from the group consisting of O ₂ —, —NH—, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a combination thereof;
Represents a polymerizable group; R ¹ represents -L ⁰ -Q or -OM; M is selected from the group consisting of a hydrogen atom, an alkali metal atom, and an optionally substituted ammonium group. Wherein the discotic liquid crystal molecules are oriented at an average tilt angle of 50 to 90 degrees with respect to the transparent support surface. Optical compensation sheet. 4. The discotic liquid crystalline molecules in the optically anisotropic layer are twisted and oriented with a twist angle of 90 to 3.
The optical compensatory sheet according to claim 4, wherein the angle is within a range of 60 degrees. 5. An STN type liquid crystal display device comprising an STN type liquid crystal cell, polarizing plates disposed on both sides of the STN type liquid crystal cell, and an optical compensation sheet disposed between the STN type liquid crystal cell and one or both polarizing plates. Wherein the optical compensation sheet has a transparent support, a liquid crystal alignment film, and an optically anisotropic layer formed from discotic liquid crystalline molecules in this order from the polarizing plate side, and the liquid crystal alignment film has the following formula: 3] [Wherein, X represents a tetravalent group containing an aromatic ring, an aliphatic ring or a heterocyclic ring; Y represents a divalent group containing an aromatic ring; provided that at least one of X and Y One has a hydrocarbon group having 10 to 100 carbon atoms as a substituent; L ⁰ is a single bond, -O-, -CO-, -S-, -S
Q represents a divalent linking group selected from the group consisting of O ₂ —, —NH—, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a combination thereof;
Represents a polymerizable group; R ¹ represents -L ⁰ -Q or -OM; M is selected from the group consisting of a hydrogen atom, an alkali metal atom, and an optionally substituted ammonium group. The optically anisotropic layer has a discotic liquid crystalline molecule having a twisted orientation in the range of 90 to 360 degrees. 50-9 for surface
An STN liquid crystal display device, wherein the liquid crystal display device is oriented at an average inclination angle in a range of 0. 6. The following formula: [Wherein, X represents a tetravalent group containing an aromatic ring, an aliphatic ring or a heterocyclic ring; Y represents a divalent group containing an aromatic ring; provided that at least one of X and Y One has a hydrocarbon group having 10 to 100 carbon atoms as a substituent; L ⁰ is a single bond, -O-, -CO-, -S-, -S
Q represents a divalent linking group selected from the group consisting of O ₂ —, —NH—, an alkylene group, an alkenylene group, an alkynylene group, an arylene group, and a combination thereof;
Represents a polymerizable group; R ¹ represents -L ⁰ -Q or -OM; M is selected from the group consisting of a hydrogen atom, an alkali metal atom, and an optionally substituted ammonium group. Using a liquid crystal alignment film containing a polymer having a repeating unit represented by the following formula: and aligning the discotic liquid crystal molecules at an average tilt angle of 50 to 90 degrees with respect to the surface of the transparent support. How to let.