JP2005275083A - Alignment layer, phase difference layer and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an alignment layer useful to produce a liquid crystal alignment layer and a phase difference layer for a liquid crystal display, having an in-plane switching mode for performing display by the in-plane rotation of a liquid crystalline compound. <P>SOLUTION: The alignment layer for liquid crystal has at least one structural unit, selected from two prescribed expressions and at least one structural unit selected from two prescribed expressions. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to an in-plane switching mode liquid crystal display device that performs display by applying a horizontal electric field to a liquid crystal compound oriented in the horizontal direction. The present invention also relates to a retardation film and an alignment film useful for producing the retardation film.

  As a liquid crystal display device, a so-called TN mode, in which a liquid crystal layer in which nematic liquid crystal is twisted and arranged between two orthogonal polarizing plates, and an electric field is applied in a direction perpendicular to the substrate is widely used. In this method, since the liquid crystal rises with respect to the substrate during black display, birefringence due to the liquid crystalline compound occurs when viewed from an oblique direction, and light leakage occurs. To solve this problem, a system for optically compensating the liquid crystal cell and preventing this light leakage by using a film in which liquid crystal molecules are hybrid-aligned has been put into practical use. However, even if liquid crystal molecules are used, it is very difficult to completely optically compensate the liquid crystal cell without any problem, resulting in a problem that gradation reversal in the lower direction of the screen cannot be suppressed.

In order to solve such a problem, a liquid crystal display device using a so-called in-plane switching (IPS) mode in which a lateral electric field is applied to the liquid crystal, or a liquid crystal having a negative dielectric anisotropy is vertically aligned in the panel. A vertical alignment (VA) mode in which alignment is divided by protrusions and slit electrodes has been proposed and put into practical use. In recent years, these panels have been developed not only for monitor applications but also for TV applications, and screen brightness has been greatly improved accordingly.
For this reason, slight light leakage in the diagonally oblique incidence direction during black display, which has not been considered as a problem in these operation modes, has become apparent as a cause of deterioration in display quality.

As one means for improving the color tone and the viewing angle of black display, the arrangement of an optical compensation material having birefringence characteristics between the liquid crystal layer and the polarizing plate is also studied in the IPS mode. For example, a white display or halftone display is viewed directly from an oblique direction by placing a birefringent medium having optical axes orthogonal to each other between the substrate and the polarizing plate to compensate for the increase / decrease in retardation of the liquid crystal layer during tilting. It is disclosed that the coloring in the case can be improved (for example, refer to Patent Document 1). In addition, a method using an optical compensation film made of a styrenic polymer having a negative intrinsic birefringence or a discotic liquid crystalline compound (see, for example, Patent Documents 2 to 4) or an optical axis as an optical compensation film having a positive birefringence. Is a method of combining a film in the plane of the film with a film having a positive birefringence and an optical axis in the normal direction of the film (see, for example, Patent Document 5), biaxiality with a retardation of half wavelength The method using the optical compensation sheet (for example, see Patent Document 6), a method of using a film having a negative retardation as a protective film of a polarizing plate, and providing an optical compensation layer having a positive retardation on this surface ( For example, see Patent Document 7).
Patent Document 4 discloses a film in which the disc surface of the discotic liquid crystalline compound is aligned and fixed so that the disc surface is substantially perpendicular to the surface direction of the support. Such a discotic liquid crystalline compound is disclosed. An alignment film having a special molecular structure is disclosed as a technique for orienting the film substantially vertically (see, for example, Patent Documents 8 to 11).

Japanese Patent Laid-Open No. 9-80424 Japanese Patent Laid-Open No. 10-54982 JP-A-11-202323 Japanese Patent Laid-Open No. 9-292522 JP 11-133408 A JP-A-11-305217 JP-A-10-307291 JP 2000-56310 A JP 2000-104073 A JP 2000-105316 A JP 2002-90545 A

  However, many of the proposed methods are methods that improve the viewing angle by canceling the birefringence anisotropy of the liquid crystal in the liquid crystal cell, so the polarization axis crossing angle when the orthogonal polarizing plate is viewed from an oblique direction. There is a problem that the light leakage based on the deviation from orthogonality cannot be solved sufficiently. Even in a system that can compensate for this light leakage, it is very difficult to completely optically compensate the liquid crystal cell without any problem. Furthermore, in the optical compensation sheet for IPS mode liquid crystal cell that performs optical compensation with the stretched birefringent polymer film, it is necessary to use a plurality of films. As a result, the thickness of the optical compensation sheet increases, and the display device becomes thinner. It is disadvantageous. Moreover, since an adhesive layer is used for lamination | stacking of a stretched film, the adhesive layer contracted by the temperature / humidity change, and defects, such as peeling and curvature between films, may generate | occur | produce. In order to solve these problems, a technique for aligning the discotic liquid crystalline compound substantially vertically as described later in the present invention is required. However, in the conventional technique, an alignment defect occurs, There was a problem such as a rush.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an IPS liquid crystal display device with a simple configuration and not only display quality but also a viewing angle that is remarkably improved. Another object of the present invention is to provide an optical compensation sheet that contributes to an improvement in the viewing angle of a liquid crystal display device, particularly an IPS liquid crystal display device, and an alignment film useful for the production of the optical compensation sheet.

  The object of the present invention has been achieved by the alignment films (1) to (4) below, the retardation films (5) to (7) below, and the liquid crystal display devices (8) to (15).

  Hereinafter, embodiments of the alignment film, the optical compensation sheet, and the liquid crystal display device of the present invention will be sequentially described. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. FIG. 1 is a schematic diagram showing an example of a pixel region of the liquid crystal display device of the present invention. FIG. 2 is a schematic view of an embodiment of the liquid crystal display device of the present invention.

（一般式（Ｉ）中、Ｒ¹は水素原子、メチル基、ハロゲン原子、またはシアノ基を表し、Ｌ¹¹は単結合、脂肪族基、２価の芳香族基または２価のヘテロ環基あるいはそれらの組み合わせからなる２価の連結基を表し、Ｐ¹¹は−Ｏ−、−ＮＲ¹¹−、−ＣＯ−、−Ｓ−、−ＳＯ−または−ＳＯ₂−あるいはそれらの組み合わせからなる２価の連結基を表し、Ｒ¹¹は水素原子または炭素数１〜６のアルキル基を表し、Ｌ¹²は２価の脂肪族基、２価の芳香族基または２価のヘテロ環基あるいはそれらの組み合わせからなる２価の連結基を表し、Ｘ¹は水素結合性基を表し、ｎ１は０〜３の整数を表す。ｎ１が２以上のとき、それぞれの、Ｐ¹¹およびＬ¹²は同一でも異なっていてもよい。）
一般式（II）

（一般式（II）中、Ｌ²¹は単結合、脂肪族基、２価の芳香族基または２価のヘテロ環基あるいはそれらの組み合わせからなる２価の連結基を表し、Ｐ²¹は−Ｏ−、−ＮＲ²¹−、−ＣＯ−、−Ｓ−、−ＳＯ−または−ＳＯ₂−あるいはそれらの組み合わせからなる２価の連結基を表し、Ｒ²¹は水素原子または炭素数が１〜６のアルキル基を表し、Ｌ²²は２価の脂肪族基、２価の芳香族基または２価のヘテロ環基あるいはそれらの組み合わせからなる２価の連結基を表し、Ｘ²は水素結合性基を表し、ｎ２は０〜３の整数を表す。ｎ２が２以上のとき、それぞれの、Ｐ²¹およびＬ²²は同一でも異なっていてもよい。）
一般式（III）

（一般式（III）中、Ｒ³は水素原子、メチル基、ハロゲン原子、またはシアノ基を表し、Ｌ³¹は単結合、２価の芳香族基または２価のヘテロ環基を表し、Ｐ³¹は−Ｏ−、−ＮＲ³¹−、−ＣＯ−、−Ｓ−、−ＳＯ−または−ＳＯ₂−あるいはそれらの組み合わせからなる２価の連結基を表し、Ｒ³¹は水素原子または炭素数が１〜６のアルキル基を表し、Ｌ³²は単結合、２価の脂肪族基、２価の芳香族基または２価のヘテロ環基あるいはそれらの組み合わせからなる２価の連結基を表し、Ｘ³は脂肪族基、芳香族基またはヘテロ環基あるいはそれらの組み合わせからなる基を表し、ｎ３は０〜３の整数を表す。ｎ３が２以上のとき、それぞれの、Ｐ³¹およびＬ³²は同一でも異なっていてもよい。）
一般式（IV）

（一般式（IV）中、Ｌ⁴¹は２価の芳香族基または２価のヘテロ環基を表し、Ｐ⁴¹は−Ｏ−、−ＮＲ⁴¹−、−ＣＯ−、−Ｓ−、−ＳＯ−または−ＳＯ₂−あるいはそれらの組み合わせからなる２価の連結基を表し、Ｒ⁴¹は水素原子、または炭素数が１〜６のアルキル基を表し、Ｌ⁴²は単結合、２価の脂肪族基、２価の芳香族基または２価のヘテロ環基あるいはそれらの組み合わせからなる２価の連結基を表し、Ｘ⁴は脂肪族基、芳香族基またはヘテロ環基あるいはそれらの組み合わせからなる基を表し、ｎ４は０〜３の整数を表す。ｎ４が２以上のとき、それぞれの、Ｐ⁴¹およびＬ⁴²は同一でも異なっていてもよい。） (1) Liquid crystal alignment having at least one structural unit selected from the following general formula (I) and general formula (II) and at least one structural unit selected from general formula (III) and general formula (IV) film.
Formula (I)

(In the general formula (I), R ¹ represents a hydrogen atom, a methyl group, a halogen atom, or a cyano group, and L ¹¹ represents a single bond, an aliphatic group, a divalent aromatic group, a divalent heterocyclic group, or Represents a divalent linking group composed of a combination thereof, and P ¹¹ represents a divalent group composed of —O—, —NR ¹¹ —, —CO—, —S—, —SO— or —SO ₂ — or a combination thereof. R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, L ¹² represents a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof. X ¹ represents a hydrogen bonding group, and n1 represents an integer of 0 to 3. When n1 is 2 or more, each P ¹¹ and L ¹² are the same or different. May be.)
Formula (II)

(In the general formula (II), L ²¹ represents a single bond, an aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and P ²¹ represents —O —, —NR ²¹ —, —CO—, —S—, —SO—, —SO ₂ — or a combination thereof, represents a divalent linking group, and R ²¹ represents a hydrogen atom or a carbon number of 1-6. Represents an alkyl group, L ²² represents a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and X ² represents a hydrogen bonding group. N2 represents an integer of 0 to 3. When n2 is 2 or more, each P ²¹ and L ²² may be the same or different.
General formula (III)

(In the general formula (III), R ³ represents a hydrogen atom, a methyl group, a halogen atom or a cyano group, L ³¹ represents a single bond, a divalent aromatic group or a divalent heterocyclic group, and P ³¹ Represents a divalent linking group composed of —O—, —NR ³¹ —, —CO—, —S—, —SO— or —SO ₂ — or a combination thereof, and R ³¹ represents a hydrogen atom or a carbon number of 1; Represents an alkyl group of ˜6, L ³² represents a divalent linking group consisting of a single bond, a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and X ³ Represents an aliphatic group, an aromatic group, a heterocyclic group or a group thereof, and n3 represents an integer of 0 to 3. When n3 is 2 or more, each of P ³¹ and L ³² may be the same May be different.)
Formula (IV)

(In the general formula (IV), L ⁴¹ represents a divalent aromatic group or a divalent heterocyclic group, and P ⁴¹ represents —O—, —NR ⁴¹ —, —CO—, —S—, —SO—. Or -SO ₂ -or a divalent linking group composed of a combination thereof, R ⁴¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and L ⁴² represents a single bond or a divalent aliphatic group. Represents a divalent linking group comprising a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and X ⁴ represents a group comprising an aliphatic group, an aromatic group, a heterocyclic group or a combination thereof. N4 represents an integer of 0 to 3. When n4 is 2 or more, P ⁴¹ and L ⁴² may be the same or different.

(2) having a structural unit represented by the general formula (I), wherein R ¹ is a hydrogen atom or a methyl group, and L ¹¹ is a single bond, a divalent aromatic group or a divalent group. A divalent linking group comprising a heterocyclic group or a combination thereof; and P ¹¹ is a divalent linking group comprising —O—, —NR ¹¹ —, —CO— or —SO ₂ — or a combination thereof. Yes, R ¹¹ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n1 is an integer of 1 to 3, according to the above (1).
(3) having a structural unit represented by the general formula (III), wherein P ³¹ is —COO— or —CONR ³¹ —, and R ³¹ is a hydrogen atom or an alkyl having 1 to 6 carbon atoms. The alignment film for liquid crystal according to (1) or (2), which is a group.
(4) It has a structural unit represented by the general formula (III), and the L ³¹ is a divalent divalent group consisting of a single bond, a divalent aromatic group, a divalent heterocyclic group or a combination thereof. The liquid crystal according to any one of (1) to (3), wherein the liquid crystal is a linking group, and L ³² is a divalent linking group comprising a divalent aromatic group, a divalent heterocyclic group, or a combination thereof. Alignment film.

(5) A retardation film obtained by aligning and fixing a discotic liquid crystalline compound on the alignment film for liquid crystal according to any one of (1) to (4).
(6) The surface of the alignment film for liquid crystal is rubbed, and a liquid crystal composition containing the discotic liquid crystalline compound is applied and aligned on the surface of the alignment film for liquid crystal thus processed. The retardation film as described in (5).
(7) The retardation film according to (6), wherein the liquid crystal composition contains at least one additive that makes the discotic liquid crystal compound substantially vertically aligned.

(8) a first polarizing film;
An optical compensation film having a first retardation region provided on the first polarizing film and a second retardation region provided in contact with the first retardation region;
A first substrate provided on the second retardation region side of the optical compensation film; a second substrate provided opposite to the first substrate; the first substrate; A liquid crystal layer made of a nematic liquid crystal material provided between two substrates,
And the liquid crystal display device in which the liquid crystalline compound of the nematic liquid crystal material is aligned in parallel with the surfaces of the first substrate and the second substrate during black display,
The first retardation region has an in-plane retardation (Re) represented by the following formula (1) of 20 nm or less, and a thickness direction retardation (Rth) represented by the following formula (2). 20 nm to 120 nm,
The second retardation region has an optically anisotropic layer having the retardation film according to any one of (5) to (7),
The liquid crystal display device, wherein a delay axis of the second retardation region is parallel to a transmission axis of the first polarizing film and a slow axis direction of a liquid crystal compound during black display.
Expression (1) Re = (nx−ny) × d
Formula (2) Rth = ((nx + ny) / 2−nz) × d
(In the formula (1) and the formula (2), nx and ny represent the refractive index in the film (nx ≧ ny), nz represents the refractive index in the thickness direction of the film, and d represents the film Represents thickness.)

(9) The liquid crystal display device according to (8), wherein a second polarizing film is provided on the second substrate.
(10) The liquid crystal display device according to (8) or (9), wherein Re in the second retardation region is 50 nm to 200 nm.
(11) The first retardation region is composed of a plurality of layers, and at least one layer in contact with the second retardation region among the plurality of layers is as described in (1) to (4) above. The liquid crystal display device according to any one of (8) to (10), which is the alignment film according to any one of the above.
(12) The second polarizing film has a protective film on at least a film surface close to the liquid crystal layer, and the protective film has the Rth of 20 nm or less. The liquid crystal display device according to any one of the above.

(13) The liquid crystal display device according to (12), wherein the protective film is a cellulose acylate film or a norbornene film.
(14) The liquid crystal display device according to (12), wherein the protective film includes a cellulose acylate film and a layer containing a vertically aligned rod-like liquid crystal compound.
(15) The first polarizing film has a protective film on at least a film surface close to the first retardation region, and the first retardation region includes a plurality of layers. The liquid crystal display device according to claim 8, wherein one layer of the plurality of layers also serves as a protective film for the first polarizing film.

  In the present specification, “parallel” and “orthogonal” mean that the angle is within a range of strictly less than ± 10 °. In this range, an error from a strict angle is preferably less than ± 5 °, and more preferably less than ± 2 °. Further, “substantially vertical” means within a range of less than ± 20 ° from a strict vertical angle. In this range, an error from a strict angle is preferably less than ± 15 °, and more preferably less than ± 10 °. Further, the “slow axis” means a direction in which the refractive index is maximized. Further, the measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified. In addition, the description of “provided on a support” or “provided on a polarizing film” in the present invention includes the case where the support is provided on the support, etc. This also includes the case where some layer (film) is included between the body and the like.

  In this specification, “polarizing plate” is cut into a size to be incorporated into a long polarizing plate and a liquid crystal device unless otherwise specified (in this specification, “cutting” includes “punching” and “cutting out”. It is used in the meaning including both of the polarizing plates. In this specification, “polarizing film” and “polarizing plate” are distinguished from each other. “Polarizing plate” means a laminate having a transparent protective film for protecting the polarizing film on at least one side of the “polarizing film”. It shall be.

Hereinafter, the alignment film of the present invention, the retardation film of the present invention, and the liquid crystal display device will be sequentially described.
[Alignment film]
The alignment film used in the present invention includes at least one structural unit selected from the following general formula (I) or general formula (II), and at least one structural unit selected from general formula (III) or general formula (IV). It is the alignment film for liquid crystals which has.
First, general formula (I) will be described.
In general formula (I), R ¹ represents a hydrogen atom, a methyl group, a halogen atom or a cyano group, preferably a hydrogen atom, a methyl group or a halogen atom, more preferably a hydrogen atom or a methyl group. .
L ¹¹ represents a single bond, an aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a divalent linking group composed of a combination thereof, a single bond, a divalent aromatic group or a divalent group. A heterocyclic group is preferred, and a single bond is more preferred. Among the divalent aliphatic groups, the alkylene group is preferably an alkylene group having 1 to 10 carbon atoms, more preferably an alkylene group having 1 to 6 carbon atoms. For example, a methylene group, an ethylene group, a trimethylene group, etc. are mentioned. The alkenylene group preferably has 2 to 30 carbon atoms, more preferably 2 to 15 carbon atoms, and most preferably 2 to 12 carbon atoms. The alkynylene group preferably has 2 to 30 carbon atoms, more preferably 2 to 15 carbon atoms, and most preferably 2 to 12 carbon atoms. The divalent cycloaliphatic group is preferably a cyclohexane-1,2-diyl group, a 1,4-cyclohexane-1,4-diyl group, or a cyclobutane-1,3-diyl group, more preferably 1,4- A cyclohexane-1,4-diyl group and a cyclobutane-1,3-diyl group.

The alkylene group, divalent aromatic group, and divalent heterocyclic group may have a substituent. Examples of the substituent include an aliphatic group, aromatic group, heterocyclic group, halogen atom, alkoxy group (for example, methoxy group, ethoxy group, methoxyethoxy group), aryloxy group (for example, phenoxy group), arylazo group ( For example, phenylazo group), alkylthio group (for example, methylthio group, ethylthio group, propylthio group), alkylamino group (for example, methylamino group, propylamino group), arylamino group (for example, phenylamino group), acyl group (for example, , Formyl group, acetyl group, propanoyl group, octanoyl group, benzoyl group), acyloxy group (for example, acetoxy group, pivaloyloxy group, benzoyloxy group), hydroxy group, mercapto group, amino group, carboxy group, sulfo group, carbamoyl group , Sulfamoyl group, ureido group Murrell.
Examples of the aromatic ring of the divalent aromatic group include a benzene ring, an indene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, and an anthracene ring, and a benzene ring and a naphthalene ring are preferable. Examples of the divalent aromatic group include 1,4-phenylene group, 1,3-phenylene group, 1,2-phenylene group, 1,2-naphthylene group, 1,3-naphthylene group, 1,4-naphthylene group. 1,5-naphthylene group, 1,8-naphthylene group, 2,6-naphthylene group, more preferably 1,4-phenylene group, 1,3-phenylene group, 1,4-naphthylene group, 1, 5-naphthylene group and 2,6-naphthylene group.
The hetero ring of the divalent hetero ring group is preferably a 5-membered, 6-membered or 7-membered hetero ring, more preferably a 5-membered ring or a 6-membered ring. As the hetero atom constituting the hetero ring, a nitrogen atom, an oxygen atom and a sulfur atom are preferable. Examples of the hetero ring include furan ring, thiophene ring, pyrrole ring, pyrrolidine ring, oxadiazole ring, isoxadiazole ring, thiazole ring, isothiazole ring, imidazole ring, imidazoline ring, imidazolidine ring, pyrazole ring, Pyrazoline ring, pyrazolidine ring, triazole ring, furazane ring, pyran ring, thiyne ring, oxadiazole ring, thiadiazole ring, pyridine ring, piperidine ring, oxazine ring, morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, Examples of the divalent heterocyclic group containing a piperazine ring and a triazine ring include pyridine-2,5-diyl group, pyridine-2,4-diyl group, pyrimidine-2,5-diyl group, and pyrimidine-2. , 4-diyl group and 1,3,5-triazine-2,4-diyl group are preferred. There.

P ¹¹ represents a divalent linking group composed of —O—, —NR ¹¹ —, —CO—, —S—, —SO—, —SO ₂ or a combination thereof, preferably —O—, —NR ¹¹ -or -CO- or a divalent linking group composed of a combination thereof, R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, preferably a hydrogen atom or 1 to 4 carbon atoms. An alkyl group, more preferably a hydrogen atom, a methyl group or an ethyl group.

L ¹² represents a divalent aliphatic group (the aliphatic group may be cyclic), a divalent aromatic group, a divalent heterocyclic group, and a divalent linking group composed of a combination thereof; Preferably, it is a divalent aromatic group.
n1 is an integer of 0 to 3, preferably 1. When n1 is 2 or more, each P ¹¹ and L ¹² may be the same or different.
A divalent aliphatic group of L ^12, a divalent aromatic group, the divalent heterocyclic group is preferably used those mentioned L ^11.

X ¹ represents a hydrogen bonding group. As the hydrogen bonding group, a hydroxyl group, a carboxy group, a carbamoyl group, a sulfamoyl group, an acylamino group or a ureido group is preferable, and a carboxy group, a carbamoyl group, a sulfamoyl group and a ureido group are more preferable. n1 represents an integer of 1 to 3.

Next, general formula (II) will be described.
L ²¹ represents a divalent linking group composed of a single bond, an aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and the divalent fat in L ¹¹ of the general formula (I) It is synonymous with an aromatic group, a divalent aromatic group or a divalent heterocyclic group, preferably a single bond, a divalent aromatic group or a divalent heterocyclic group, more preferably a divalent aromatic group.
P ²¹ represents a divalent linking group composed of —O—, —NR ²¹ —, —CO—, —S—, —SO—, —SO ₂ —, or a combination thereof.
L ²² represents a divalent linking group composed of a divalent aliphatic group (the aliphatic group may be cyclic), a divalent aromatic group, a divalent heterocyclic group, or a combination thereof.
X ² represents a hydrogen bonding group and has the same meaning as X ^{1 in} formula (I), and the preferred range is also the same.
n2 is an integer of 0 to 3, preferably 0 or 1, and more preferably 0. When n2 is 2 or more, each P ²¹ and L ²² may be the same or different.

  Although the specific example of the repeating unit represented by general formula (I) and general formula (II) of this invention below is shown, this invention is not limited to this.

In the general formula (III), R ³ represents a hydrogen atom, a methyl group, a halogen atom or a cyano group, L ³¹ represents a single bond, a divalent aromatic group or a divalent heterocyclic group, and P ³¹ represents A divalent linking group consisting of —O—, —NR ³¹ —, —CO—, —S—, —SO— or —SO ₂ — or a combination thereof, R ³¹ represents a hydrogen atom or a carbon number of 1 Represents an alkyl group of ˜6, L ³² represents a divalent linking group consisting of a single bond, a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and X ³ Represents a group composed of a cyclic aliphatic group, an aromatic group, a heterocyclic group and a combination thereof, and n3 is an integer of 0 to 3. When n3 is 2 or more, each P ³¹ and L ³² may be the same or different.

In general formula (III), R < ³ > is synonymous with R < ¹ > of general formula (I), and its preferable range is also synonymous.
Divalent aromatic groups and divalent heterocyclic groups of L ³¹ has the same meaning as L ^11, P ³¹ has the same meaning as P ¹¹ in the general formula (I). These preferable ranges are also synonymous.
The divalent aliphatic group represented by L ³² (the aliphatic group may be cyclic), a divalent aromatic group, a divalent heterocyclic group and a combination thereof are represented by the general formula: the same meaning as L ¹¹ in (I). A preferred range is a divalent linking group comprising a divalent aliphatic group, a divalent aromatic group, or a combination thereof.
X ³ represents an aliphatic group, an aromatic group, a heterocyclic group, or a group consisting of a combination thereof.
Examples of the aliphatic group include a linear or branched alkyl group, and a cyclic aliphatic group. As an alkyl group, a C1-C15 alkyl group is preferable, More preferably, a C1-C10 alkyl group is preferable. Examples thereof include a methyl group, an ethyl group, a butyl group, a 2-ethylhexyl group, a t-butyl group, and a t-amyl group. The cycloaliphatic group is preferably a cyclohexyl group, a cyclopentyl group, a cyclobutyl group, or an adamantyl group, more preferably a cyclohexyl group or an adamantyl group. The aromatic ring of the aromatic group includes a benzene ring, an indene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, and an anthracene ring, and a phenyl group and a naphthyl group are preferable. The hetero ring of the hetero ring group is preferably a 5-membered, 6-membered or 7-membered hetero ring, more preferably a 5-membered ring or a 6-membered ring. As the hetero atom constituting the hetero ring, a nitrogen atom, an oxygen atom and a sulfur atom are preferable. Examples of heterocycles include furan ring, thiophene ring, pyrrole ring, pyrrolidine ring, oxadiazole ring, isoxadiazole ring, thiazole ring, isothiazole ring, imidazole ring, imidazoline ring, imidazolidine ring, pyrazole ring, Pyrazoline ring, pyrazolidine ring, triazole ring, furazane ring, pyran ring, thiyne ring, oxadiazole ring, thiadiazole ring, pyridine ring, piperidine ring, oxazine ring, morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, Examples of the heterocyclic group including a piperazine ring and a triazine ring include a 4-pyridyl group, a 2-pyridyl group, a 2-pyrimidyl group, a 4-pyrimidyl group, and a 1,3,5-triazin-2-yl group. preferable.
The alkyl group, aromatic group, and heterocyclic group may have a substituent. Examples of the substituent include aliphatic groups (for example, alkyl groups), aromatic groups, heterocyclic groups, halogen atoms (fluorine atoms, chlorine atoms, bromine atoms, iodine atoms), cyano groups, alkoxy groups (for example, methoxy groups). Group, ethoxy group, methoxyethoxy group), aryloxy group (for example, phenoxy group) arylazo group (for example, phenylazo), alkylthio group (for example, methylthio, ethylthio, propylthio), alkylamino group (for example, methylamino, propylamino) , Arylamino group (for example, phenylamino), acyl group (for example, formyl, acetyl, propanoyl, octanoyl, benzoyl), acyloxy group (for example, acetoxy, pivaloyloxy, benzoyloxy), hydroxy group, mercapto group, amino group, carboxy group Group, sulfo group A carbamoyl group, a sulfamoyl group, include ureido group. Further, these substituents may further have a substituent such as the above-mentioned substituents without departing from the gist of the present invention.

n3 represents an integer of 0 to 3, preferably 1 or 2. When n3 is 2 or more, each P ³¹ and L ³² may be the same or different.

Next, general formula (IV) will be described.
L ⁴¹ represents a divalent aromatic group or a divalent heterocyclic group, and is synonymous with the divalent aromatic group or divalent heterocyclic group of L ¹¹ in formula (I), and the preferred range is also synonymous. It is. P ⁴¹ represents a divalent linking group composed of —O—, —NR ⁴¹ —, —CO—, —S—, —SO— or —SO ₂ — or a combination thereof, and P ⁴¹ represents the formula (I). It has the same meaning as in P ^11, a divalent linking group preferably consisting of -O- or -CO-, or a combination thereof.
L ⁴² represents a single bond or a divalent linking group composed of a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group, or a combination thereof, and has the same meaning as L ^{32 in} formula (III). And preferably a single bond or a divalent aromatic group.
X ⁴ represents an aliphatic group (preferably a cycloaliphatic group), an aromatic group, a heterocyclic group, or a group thereof, and has the same meaning as X ^{3 in} formula (III). n4 is an integer of 0 to 3, preferably 0 or 1. When n4 is 2 or more, each of P ⁴¹ and L ⁴² may be the same or different.

  Specific examples of the repeating unit represented by the general formula (III) or the general formula (IV) are shown below, but the present invention is not limited thereto.

  The liquid crystal alignment film of the present invention may be a copolymer of a structural unit represented by general formula (I) or (II) or general formula (III) or (VI) and other structural units. As the structural unit other than the structural unit represented by the general formula (I) or (II), the general formula (III) or (VI), any structural unit may be used as long as it is copolymerizable. As the polymerization structural unit, for example, vinyl monomers (for example, acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, acrylic amides, methacrylic amides, vinyl alcohol, acyloxyvinyls, styrenes, Maleic acid, maleic acid esters, maleinamides, acrylonitrile, vinyl alkyl ketones and the like) are structural units obtained by sequential polymerization.

Polymers obtained by copolymerization with the structural units represented by general formula (I) or (II) and general formula (III) or (VI) include water-soluble groups (for example, hydroxyl group, carboxy group, sulfo group). , A quaternary ammonium group, an amino group, a phospho group, etc.) are preferred, and those substituted with a hydroxyl group or a carboxy group are particularly preferred. These substituents may be substituted with the structural unit represented by the general formula (I) or (II), or may be substituted with other structural units.
The combination of the structural unit represented by the general formula of the present application includes the structural unit represented by the general formula (I) and the structural unit represented by the general formula (III). And a structural unit represented by the general formula (IV) and a structural unit represented by the general formula (II) and a structural unit represented by the general formula (III) are preferable, The case where the structural unit represented by general formula (I) and the structural unit represented by general formula (III) are included is more preferable.

  When the liquid crystal alignment film of the present invention is a copolymer containing structural units represented by general formula (I) or (II) and general formula (III) or (VI), the general formula (I) Alternatively, the total content of the structural units represented by (II) and the general formula (III) or (VI) is preferably 1 to 100% by weight, more preferably 10 to 100% by weight, and 20 to 100% by weight. Most preferred. The total content of the structural units represented by the general formula (I) or (II) is preferably 1 to 90% by weight, more preferably 10 to 90% by weight, and most preferably 20 to 80% by weight. The total content of the structural units represented by the general formula (III) or (VI) is preferably 1 to 90% by weight, more preferably 10 to 90% by weight, and most preferably 20 to 80% by weight. Further, the composition ratio (weight ratio) of the copolymer containing the structural unit represented by the general formula (I) or (II) and the general formula (III) or (VI) is the general formula (I) or (II ) Is preferably 0.2 to 1.1, more preferably 0.5 to 0.7.

  The liquid crystal alignment film of the present invention preferably further contains a structural unit having a crosslinkable group. By including a crosslinkable group, the liquid crystal alignment film of the present invention and the liquid crystal compound are cross-linked, and the adhesion between the liquid crystal alignment film layer and the optically anisotropic layer is often improved. The crosslinkable group contained in the liquid crystal alignment film used in the present invention can be used without particular limitation such as an addition, condensation, and substitution reactive group. On the other hand, the liquid crystalline compound itself is preferably introduced by introducing an ethylenically unsaturated group such as an acryloyl group or a methacryloyl group, and fixed by irradiation with ultraviolet light using a photo radical polymerization initiator, and the polymer used in the present invention is also ultraviolet light. It preferably has a crosslinkable group that can be cross-linked by irradiation. As a preferable example of a reaction that can be cross-linked by ultraviolet irradiation, a ring-opening polymerization reaction of a heterocyclic compound such as an epoxy ring or an oxetane ring combined with a compound that generates a cation by ultraviolet irradiation and a compound that generates a radical by ultraviolet irradiation are used in combination. The radical polymerization reaction of the compound which has an ethylenically unsaturated group is mentioned. Among these, the most preferable crosslinkable group contained in the polymer is an ethylenically unsaturated group (for example, acryloyl group, methacryloyl group, styryl group, etc.). The method for introducing a crosslinkable group into the polymer of the present invention is not particularly limited.

  Although the preferable specific example of the structural unit containing a crosslinkable group is shown below, this invention is not limited to these.

  The polymer formation reaction of the liquid crystal alignment film of the present invention is not particularly limited such as addition, condensation, and substitution reaction, but the structural unit represented by the general formula (I) or (II) and the general formula (III) or (VI) It is the simplest and preferable to form by the radical polymerization reaction of the ethylenically unsaturated compound derived. On the other hand, when the liquid crystal alignment film used in the present invention has a structural unit substituted with a crosslinkable group, (a) rather than synthesizing by a method of directly introducing an ethylenically unsaturated group by polymerizing the corresponding monomer ( b) It is preferable to synthesize by a method in which an ethylenically unsaturated group is introduced into a polymer obtained by polymerizing a monomer having an arbitrary functional group by a polymer reaction. In the polymer reaction, for example, I) a functional group conversion (elimination reaction, oxidation reaction) is performed after a polymer containing a functional group obtained by precuring an ethylenically unsaturated group that removes hydrochloric acid from a 2-chloroethyl group, for example. , A reduction reaction, a deprotection reaction, etc.) to induce ethylenically unsaturated groups, and II) after a polymer containing any functional group is formed, a bond formation reaction with the functional group in the polymer proceeds. And a method of reacting a compound having both a functional group capable of forming a covalent bond and an ethylenically unsaturated group (hereinafter referred to as “reactive monomer”). These methods I) and II) may be performed in combination. The bond formation reaction referred to here can be used without particular limitation as long as it is a reaction that forms a covalent bond in the bond formation reaction generally used in the field of organic synthesis. On the other hand, the ethylenically unsaturated group contained in the polymer may be thermally polymerized and gelled during the reaction, so that the reaction proceeds at the lowest possible temperature (preferably 60 ° C. or less, particularly preferably room temperature or less). Is preferred. A catalyst may be used for the purpose of promoting the progress of the reaction, and a polymerization inhibitor may be used for the purpose of suppressing gelation.

  A preferable ratio when the liquid crystal alignment film of the present invention includes a repeating unit substituted with a crosslinkable group is 0.1 to 60% by weight, more preferably 0.3 to 50% by weight, and particularly preferably 0.5. -40% by weight.

  The preferred molecular weight range of the liquid crystal alignment film used in the present invention is 1,000 to 1,000,000, more preferably 2000 to 200,000 in terms of weight average molecular weight. Most preferably, it is 3000-100,000.

  Although the preferable example of the liquid crystal aligning film used for this invention below is shown in Table 1, this invention is not limited to this. In addition, the structural unit represented by the general formula (I) or (II), the general formula (III) or (VI), and the structural unit containing a crosslinkable substituent, which are specific examples described above, are listed above. It represents with the number of the specific example, and added the copolymerization composition ratio in weight%.

  The synthesis of the liquid crystal alignment film used in the present invention can be easily obtained by applying a known method. Although the specific synthesis example of the polymer used for this invention is described below, the synthesis example of the polymer of this invention is not limited to this.

Synthesis example of (AL-1) N, N-dimethylacetamide (300 ml) was added to a 500 mL three-necked flask to dissolve 4-aminobenzoic acid (40.3 g, 0.294 mol) and cooled to 0 ° C. Acrylic acid chloride (30.0 g, 0.331 mol) was slowly added dropwise. After completion of the dropwise addition, the reaction solution was heated to 40 ° C., and further heated and stirred for 2 hours. Then, the reaction solution was added to 3 L of water, and the precipitated solid was separated by filtration under reduced pressure, dried by blowing and quantified I-1. Obtained.
In the synthesis method of I-1, 4-aminobenzoic acid was changed to 3,5-bis (trifluoromethyl) aniline, and the same procedure was followed to quantitatively obtain III-9.
N, N-dimethylformamide (10 ml) was placed in a 100 mL three-necked flask, heated to 65 ° C. while flowing nitrogen at a flow rate of 35 ml / min, and an initiator (V-65, 7 manufactured by Wako Pure Chemical Industries, Ltd.) was used. 0.5 mg) of N, N-dimethylformamide (4 ml) was added. After 10 minutes, 6 g of I-1, 4 g of III-9, and an initiator ((Wako Pure Chemical Industries, Ltd. V-65, 18.5 mg) in N, N-dimethylformamide (20 ml) were added over 3 hours. After completion of the addition, an N, N-dimethylformamide (2 ml) solution of an initiator (V-65, 3.8 mg, manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the reaction was allowed to proceed for 3 hours at the same temperature. Thereafter, the reaction system was returned to room temperature, and then slowly poured into stirred water (800 mL), and the precipitated polymer was taken out by suction filtration and further dried. 8.7 g of AL-1) was obtained, and it was confirmed by 1H-N.M.R that the obtained solid was a polymer.

Liquid crystal alignment film coating liquid 1) Solvent Examples of the solvent used in the liquid crystal alignment film coating liquid of the present invention include water, alcohols (for example, methanol, ethanol, isopropanol, etc.), amides (for example, N, N -Dimethylformamide, etc.), acetonitrile, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate and the like, and water, alcohols, and mixed solvents thereof are preferable.

2) Concentration The liquid crystal alignment film of the present invention is 0.1 wt% to 40 wt%, preferably 0.5 wt% to 20 wt%, more preferably 2 wt% to 10 wt% in the solvent. Something is preferable.

3) Viscosity The viscosity of the coating solution in which the liquid crystal alignment film of the present invention is dissolved is 0.1 cp to 100 cp, preferably 0.5 cp to 50 cp.

4) Additive In addition to this, an additive may be appropriately added to the coating liquid containing the liquid crystal alignment film of the present invention. For example, when it is difficult to dissolve in a water-soluble solvent, for example, a basic compound (for example, sodium hydroxide, lithium hydroxide, triethylamine, etc.) or an acidic compound (for example, hydrochloric acid, acetic acid, succinic acid, etc.) is added. May be dissolved.

  The content of the polymer in the composition for forming an alignment film (a composition excluding the solvent in the case of a coating solution) is preferably 5% by mass to 100% by mass, and 10% by mass to 100% by mass. More preferably.

  The alignment film can be basically formed by applying the polymer as an alignment film forming material and a solution containing an additive as required onto a transparent support, followed by heat drying and rubbing treatment. . In the alignment film of the present invention, since a water-soluble polymer is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an orientation film and also an optically anisotropic layer reduces remarkably.

  The alignment film is preferably provided in direct contact with the transparent support. The alignment film can be obtained by drying the polymer layer and then rubbing the surface. For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. In general, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are flocked on average.

  Next, the alignment film is caused to function to align the discotic liquid crystalline compound of the optically anisotropic layer provided on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent. The thickness of the alignment film is preferably in the range of 0.1 to 10 μm.

Production of retardation plate [Optical compensation sheet]
The optical compensation sheet of the present invention has an optically anisotropic layer formed from a discotic liquid crystalline compound whose orientation is controlled on the alignment film of the present invention. The alignment film of the present invention is useful for vertically aligning molecules of a discotic liquid crystalline compound. Therefore, by using the alignment film of the present invention, it is possible to easily form a layer exhibiting optical anisotropy expressed by vertically aligning the molecules of the discotic liquid crystalline compound. The optical compensation sheet of the present invention may consist of only one optically anisotropic layer or a laminate of two or more layers. Moreover, the laminated body with the optically anisotropic layer and / or polymer film which consist of another liquid crystal composition may be sufficient.

  When the optical compensation sheet of the present invention is applied to an IPS type liquid crystal display device, the optical compensation sheet of the present invention is a composition containing at least the alignment film of the present invention and a discotic liquid crystalline compound (preferably triphenylene liquid crystal). And a retardation region composed of an optically anisotropic layer in which molecules of the discotic liquid crystalline compound are substantially vertically aligned, Re (defined later) is 20 nm or less, and Rth (defined) An embodiment comprising a retardation region of 20 nm to 150 nm is preferable.

  The composition used for forming the optically anisotropic layer contains at least a discotic liquid crystalline compound. The composition of the present invention may contain an additive that produces a state in which the molecules of the discotic liquid crystalline compound are substantially vertically aligned. The composition preferably contains an air interface side vertical alignment agent that contributes to vertical alignment of the molecules of the discotic liquid crystalline compound on the air interface side. Further, the composition may contain an alignment film interface side vertical alignment agent that contributes to the vertical alignment of the molecules of the discotic liquid crystalline compound.

(Discotic liquid crystalline compounds)
The discotic liquid crystalline compound contained in the composition of the present invention is more preferably a triphenylene liquid crystal. Discotic liquid crystalline compounds are disclosed in various documents (C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); edited by The Chemical Society of Japan, Quarterly Chemical Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794 (1985); J. Zhang et al., J Am.Chem.Soc., Vol.116, page 2655 (1994)). The polymerization of discotic liquid crystalline compounds is described in JP-A-8-27284.

The discotic liquid crystalline compound preferably has a polymerizable group so that it can be fixed by polymerization. For example, a structure in which a polymerizable group is bonded as a substituent to a discotic core of a discotic liquid crystalline compound is conceivable. However, when a polymerizable group is directly connected to the discotic core, the alignment state is maintained in the polymerization reaction. It becomes difficult. Therefore, a structure having a linking group between the discotic core and the polymerizable group is preferable. That is, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula.
D (-LP) n
In the formula, D is a discotic core, L is a divalent linking group, P is a polymerizable group, and n is an integer of 4 to 12. Preferred specific examples of the discotic core (D), the divalent linking group (L) and the polymerizable group (P) in the above formula are (D1) to (D15) described in JP-A No. 2001-4837, respectively. ), (L1) to (L25), and (P1) to (P18), and the contents described in the publication can be preferably used.
In addition, the discotic nematic liquid crystal phase-solid phase transition temperature of the liquid crystal compound is preferably 70 to 300 ° C, and more preferably 70 to 170 ° C.

(Polymerization initiator)
The vertically aligned discotic liquid crystalline compound is preferably fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction of the polymerizable group (P) introduced into the liquid crystal compound. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Description), acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).

The amount of the photopolymerization initiator used is preferably 0.01 to 20% by weight, more preferably 0.5 to 5% by weight, based on the solid content of the coating solution. The light irradiation for polymerizing the molecules of the discotic liquid crystalline compound preferably uses ultraviolet rays. The irradiation energy is preferably ^{20mJ / cm 2 ~50J / cm 2} , further preferably 100 to 800 mJ / cm ^2. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions. The thickness of the retardation layer is preferably 0.1 to 10 μm, more preferably 0.5 to 5 μm, and most preferably 1 to 5 μm.

(Air interface side vertical alignment agent)
Since normal discotic liquid crystalline compounds have the property of being tilted and aligned on the air interface side, in order to obtain a uniformly vertically aligned state, the discotic liquid crystalline compound must also be vertically controlled on the air interface side. is required. As the air interface side vertical alignment agent of the discotic liquid crystalline compound, the compounds described in JP-A Nos. 2002-20363 and 2002-129162 are used as the air interface side vertical alignment agent. be able to. Also, paragraph numbers 0072 to 0075 of Japanese Patent Application No. 2002-212100, paragraph numbers 0038 to 0040 and 0048 to 0049 of Japanese Patent Application No. 2002-243600, and paragraph numbers 0037 to 0039 of Japanese Patent Application No. 2002-262239. The matters described in Paragraph Nos. 0071 to 0078 of Japanese Patent Application No. 2003-91752 can also be appropriately applied to the present invention. When used for forming an optically anisotropic layer, the composition (in the case of a coating solution, the composition excluding the solvent is preferably 0.005 to 8% by mass, and 0.01 to 5% by mass. More preferably, it is 0.05 to 1% by mass.

(Other additives for optically anisotropic layers)
Along with the liquid crystal compound, a plasticizer, a surfactant, a polymerizable monomer, and the like can be used in combination to improve the uniformity of the coating film, the strength of the film, the orientation of the liquid crystal compound, and the like. These materials are preferably compatible with the liquid crystal compound and do not inhibit the alignment.
Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the polymerizable group-containing liquid crystalline compound. Examples thereof include those described in paragraph numbers 0018 to 0020 in JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specifically, for example, the compounds described in paragraph Nos. 0028 to 0056 in JP-A-2001-330725 and the compounds described in paragraph Nos. 0069 to 0126 in Japanese Patent Application No. 2003-295212 are exemplified. .

  The polymer used together with the liquid crystal compound is preferably capable of thickening the coating solution. A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph No. 0178 in JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and in the range of 0.1 to 8% by mass with respect to the liquid crystal molecules so as not to inhibit the alignment of the liquid crystal compound. It is more preferable.

  One embodiment of the optical compensation sheet of the present invention can be produced by applying the composition on the alignment film of the present invention and vertically aligning the molecules of the discotic liquid crystalline compound. After applying the composition on the alignment film, if necessary, the alignment film polymer is reacted with the polyfunctional monomer contained in the optically anisotropic layer, or the alignment film polymer is crosslinked using a crosslinking agent. May be.

(Coating solvent)
As the solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination. The coating liquid can be applied by a known method (eg, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

[Support]
In the present invention, a transparent support may be used. As the transparent support, it is preferable to use a polymer film having a small wavelength dispersion. The transparent support preferably has a small optical anisotropy. That the support is transparent means that the light transmittance is 80% or more. Specifically, the small chromatic dispersion means that the ratio of Re ₄₀₀ / Re ₇₀₀ is preferably less than 1.2. Specifically, the small optical anisotropy means that in-plane retardation (Re) is preferably 20 nm or less, and more preferably 10 nm or less. Examples of the polymer include cellulose ester, 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 cast method. The thickness of the transparent support is preferably 20 to 500 μm, and more preferably 50 to 200 μm. In order to improve adhesion between the transparent support and the layer (adhesive layer, vertical alignment film or retardation layer) provided thereon, surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet light (UV) ) Treatment, flame treatment). An adhesive layer (undercoat layer) may be provided on the transparent support. Moreover, the average particle diameter is 10 to 100 nm in order to provide the transparent support or the long transparent support with slipperiness in the conveying process or to prevent the back surface and the surface from sticking after winding. It is preferable to use what formed the polymer layer which mixed the inorganic particle of about 5%-40% by solid content weight ratio by the application | coating or co-casting with the support body on the one side of the support body.

  Next, an embodiment in which the present invention is used for an optical compensation film of an IPS type liquid crystal display device having an optically anisotropic layer formed using the alignment film of the present invention will be described. FIG. 1 is a schematic diagram showing an example of a pixel region of the liquid crystal display device of the present invention. FIG. 2 is a schematic view of an embodiment of the liquid crystal display device of the present invention.

[Liquid Crystal Display]
The liquid crystal display device shown in FIG. 2 includes a first polarizing film 8, an optical compensation film 10, a first substrate 14, a liquid crystal layer 16, a second substrate 18, and a second polarizing film 21. Have. The first polarizing film 8 and the second polarizing film 21 are sandwiched between protective films 7a and 7b and 20a and 20b, respectively. The optical compensation film 10 includes a first retardation region 11 including a protective film 7 b in contact with the first polarizing film 8 and a second retardation region 12 in contact with the first phase region 11.

  In the liquid crystal display device of FIG. 2, the liquid crystal cell includes a first substrate 14 and a second substrate 17, and a liquid crystal layer 16 sandwiched therebetween. The product Δn · d of the thickness d (μm) of the liquid crystal layer and the refractive index anisotropy Δn is optimal in the range of 0.2 to 0.4 μm for the IPS type having no twisted structure in the transmission mode. In this range, the white display luminance is high and the black display luminance is small, so that a bright and high-contrast display device can be obtained. An alignment film (not shown) is formed on the surfaces of the substrates 14 and 18 that are in contact with the liquid crystal layer 16 so that the liquid crystal molecules are aligned substantially parallel to the surface of the substrate and are rubbed on the alignment film. By the processing directions 15 and 19 and the like, the alignment direction of liquid crystal molecules in a state in which no voltage is applied or in a low application state is controlled. An electrode (not shown in FIG. 2) capable of applying a voltage to the liquid crystal molecules is formed on the inner surface of the substrate 14 or 17.

  FIG. 1 schematically shows the alignment of liquid crystal molecules in one pixel region of the liquid crystal layer. FIG. 1 shows the alignment of liquid crystal molecules in a very small area corresponding to one pixel of the liquid crystal layer 16 in FIG. 2 in the rubbing direction 4 of the alignment film formed on the inner surfaces of the substrates 14 and 18; It is the schematic diagram shown with the electrodes 2 and 3 which can apply a voltage to the liquid crystal molecule formed in the inner surface of the board | substrates 14 and 18. FIG. When active driving is performed using a nematic liquid crystal having positive dielectric anisotropy as a field effect liquid crystal, the liquid crystal molecule alignment directions in a no voltage application state or a low application state are 5a and 5b. A display is obtained. When applied between the electrodes 2 and 3, the liquid crystal molecules change their alignment direction in the directions of 6 a and 6 b in accordance with the voltage. Usually, bright display is performed in this state.

  In FIG. 2 again, the transmission axis 9 of the first polarizing film 8 and the transmission axis 22 of the second polarizing film 21 are arranged orthogonally. The optical compensation film 10 is composed of two regions, a first retardation region 11 and a second retardation region 12. The slow axis 13 of the second retardation region 12 is parallel to the transmission axis 9 of the first polarizing film 8 and the slow axis direction 17 of the liquid crystal molecules in the liquid crystal layer 16 during black display, and The second retardation region 12 is disposed closer to the liquid crystal layer 16 than the first retardation region 11. In the second retardation region, a composition containing a discotic liquid crystalline compound is applied on the alignment film of the present invention, and molecules of the discotic liquid crystalline compound are substantially vertically aligned and fixed in that state. The optically anisotropic layer formed by The optical characteristics of the two regions constituting the optical compensation film will be described later.

  The liquid crystal display device shown in FIG. 2 shows a configuration in which the first polarizing film 8 is sandwiched between the two protective films 7a and 7b, but the protective film 7b may be omitted. In the case of disposing the protective film 7b, in the present invention, the protective film 7b is one of the layers constituting the first retardation region 11. In the liquid crystal display device shown in FIG. 2, the second polarizing film 21 is also sandwiched between two protective films 20a and 20b. The thickness direction retardation Rth of the protective film 20a on the side close to the liquid crystal layer 16 is preferably 20 nm or less.

  In addition, in FIG. 2, although the aspect of the display device of the transmission mode provided with the upper side polarizing plate and the lower side polarizing plate was shown, this invention may be the aspect of the reflection mode provided with only one polarizing plate, In such a case, since the optical path in the liquid crystal cell is doubled, the optimum value of Δn · d is about the above half value.

  The liquid crystal display device of the present invention is not limited to the configuration shown in FIGS. 1 and 2, and may include other members. For example, a color filter may be disposed between the liquid crystal layer and the polarizing film. Further, an antireflection treatment or a hard coat may be applied to the surface of the protective film of the polarizing film. Moreover, you may use what gave electroconductivity to the structural member. In the case of use as a transmission type, a cold cathode or a hot cathode fluorescent tube, or a backlight having a light emitting diode, a field emission element, or an electroluminescent element as a light source can be disposed on the back surface. In addition, a reflective polarizing plate, a diffusion plate, a prism sheet, or a light guide plate can be disposed between the liquid crystal layer and the backlight. In addition, the liquid crystal display device of the present invention may be of a reflective type. In such a case, only one polarizing plate may be disposed on the observation side, and reflected on the back surface of the liquid crystal cell or the inner surface of the lower substrate of the liquid crystal cell. Place the membrane. Of course, it is also possible to provide a front light using the light source on the liquid crystal cell observation side.

  The liquid crystal display device of the present invention includes an image direct view type, an image projection type, and a light modulation type. The present invention is particularly effective when applied to an active matrix liquid crystal display device using a three-terminal or two-terminal semiconductor element such as TFT or MIM. Of course, a mode applied to a passive matrix liquid crystal display device called time-division driving is also effective.

(First retardation region of optical compensation film)
The optical characteristics of the first retardation region are represented by Re = (nx−ny) × using in-plane refractive indexes nx and ny (nx ≧ ny), a refractive index nz in the thickness direction, and a thickness d of the film. The in-plane retardation (Re) defined by d is 20 nm or less, more preferably 10 nm or less, and even more preferably 5 nm or less. The thickness direction retardation Rth defined by Rth = ((nx + ny) / 2−nz) × d is 20 nm to 120 nm, and more preferably 40 nm to 100 nm. When the protective film 7b that protects the first polarizing film 8 has optical anisotropy, the protective film 7b is a layer that constitutes the first retardation region 11, and therefore the Rth of the protective film. And the sum of Rth of other layers is required to be 40 nm to 100 nm.

  The retardation region having this optical characteristic includes a retardation region composed of a birefringent polymer film, and an optically anisotropic layer formed by applying or transferring a low-molecular or high-molecular liquid crystalline compound on a transparent support. Although there is a phase difference region, any of them can be used in the present invention.

  The retardation region composed of the birefringent polymer film having the optical characteristics can be easily formed by biaxially stretching the polymer film. In addition, cellulose acylates that exhibit this optical property by simply casting without stretching can be suitably used. As such cellulose acylate, those described in JP-A-2002-90541 can be used. As a material for the polymer film, a synthetic polymer (eg, polycarbonate, polysulfone, polyethersulfone, polyacrylate, polymethacrylate, norbornene resin, cellulose acylate) is generally used.

  As a retardation region formed on a transparent support by coating or transfer, a rod-like cholesteric liquid crystal composition containing a chiral structural unit is aligned after its helical axis is oriented substantially perpendicular to the substrate, Examples thereof include those obtained by horizontally aligning a discotic liquid crystalline compound having a negative intrinsic birefringence (the director is perpendicular to the substrate) and those obtained by casting and fixing a polyimide polymer on the substrate.

(Second retardation region of optical compensation film)
The second retardation region is formed on the alignment film of the present invention by optically aligning the molecules of the discotic liquid crystalline compound substantially vertically in the presence of the fluorine-based polymer or the fluorine-containing compound. It consists of an isotropic layer. The optically anisotropic layer is formed by applying a composition containing a discotic liquid crystalline compound and an air interface side vertical alignment control agent on the alignment film of the present invention. In the isotropic layer, the molecules of the discotic liquid crystal compound are fixed in a substantially vertically aligned state and exhibit predetermined optical characteristics. The optical compensation film is arranged so that the slow axis of the second retardation region is parallel to the transmission axis of the first polarizing film and the slow axis direction of the liquid crystal compound in the liquid crystal layer during black display. The The Re of the second retardation region is preferably 50 nm to 200 nm, and more preferably 80 nm to 160 nm. This adjustment of Re is performed by controlling the thickness of the discotic liquid crystal layer to be formed by coating. Further, the discotic liquid crystalline compound needs to be aligned substantially perpendicular to the film surface (average inclination angle in the range of 70 to 90 degrees). When the average inclination angle is smaller than this, the light leakage distribution becomes asymmetric. Substantially perpendicular means that the average angle (average inclination angle) between the disk surface and the surface of the optically anisotropic layer is in the range of 70 ° to 90 °. These discotic liquid crystalline compounds may be aligned obliquely or may be changed so that the inclination angle gradually changes (hybrid alignment). Even in the case of oblique orientation or hybrid orientation, the average inclination angle is preferably 70 ° to 90 °, more preferably 75 ° to 90 °, and most preferably 80 ° to 90 °. As described above, the polymer represented by the general formula (1) and the quaternary onium salt contribute to making the discotic liquid crystalline compound (preferably triphenylene liquid crystal) in such a vertically aligned state.

  The second retardation region may consist only of an optically anisotropic layer formed from the composition of the present invention, or may consist of the optically anisotropic layer and other layers. Also good. In the latter case, a laminate with a stretched polystyrene film or a laminate with an optically isotropic film such as a cycloolefin can be suitably used.

(Second protective film for polarizing plate)
The second polarizing plate protective film preferably has no absorption in the visible light region, a light transmittance of 80% or more, and a small retardation based on birefringence. Specifically, the in-plane 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 preferably 20 nm or less, more preferably 10 nm or less, and most preferably 5 nm or less. Any film having this property can be preferably used, but from the viewpoint of durability of the polarizing film, a cellulose acylate or norbornene film is more preferable. As a method for reducing the Rth of the cellulose acylate film, it is effective to mix a liquid crystalline compound into the film.

(Bar-shaped liquid crystalline compound)
The liquid crystal display device of the present invention may have a retardation layer formed from a composition containing a rod-like liquid crystalline compound. As will be described later, the protective film of the second polarizing film is preferably a retardation layer formed from a composition containing a polymer film, preferably a cellulose acylate polymer film, and a rod-like liquid crystalline compound. . Examples of the rod-like liquid crystal compound used for forming the optically anisotropic layer include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, Cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only the low-molecular liquid crystalline molecules as described above but also high-molecular liquid crystalline molecules can be used.

  In the liquid crystal display device of the present invention, it is preferable to use an optically anisotropic layer in which rod-like liquid crystalline compounds are substantially vertically aligned. In the case of a rod-like liquid crystalline compound, “substantially perpendicular” means that the angle formed by the film surface and the director of the rod-like liquid crystalline compound is in the range of 70 ° to 90 °. The rod-like liquid crystalline compound may be oriented obliquely or may be changed so that the inclination angle gradually changes (hybrid orientation). Even in the case of oblique orientation or hybrid orientation, the average inclination angle is preferably 70 ° to 90 °, more preferably 75 ° to 90 °, and most preferably 80 ° to 90 °.

(Vertical alignment film)
In order to align the rod-like liquid crystalline compound vertically on the alignment film side, it is important to reduce the surface energy of the alignment film. Specifically, the surface energy of the alignment film is lowered by the functional group of the polymer, thereby bringing the rod-like liquid crystal compound into a standing state. As the functional group for reducing the surface energy of the alignment film, a fluorine atom and a hydrocarbon group having 10 or more carbon atoms are effective. In order to make a fluorine atom or a hydrocarbon group exist on the surface of the alignment film, it is preferable to introduce a fluorine atom or a hydrocarbon group into the side chain rather than the main chain of the polymer. The fluoropolymer preferably contains fluorine atoms in a proportion of 0.05 to 80% by weight, more preferably in a proportion of 0.1 to 70% by weight, and in a proportion of 0.5 to 65% by weight. More preferably, it is most preferably contained in a proportion of 1 to 60% by weight. 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 exhibit strong hydrophilicity, such as a halogen atom. The number of carbon atoms of the hydrocarbon group is preferably 10 to 100, more preferably 10 to 60, and most preferably 10 to 40. The main chain of the polymer preferably has a polyimide structure or a polyvinyl alcohol structure.

  Polyimide is generally synthesized by a condensation reaction of tetracarboxylic acid and diamine. A polyimide corresponding to a copolymer may be synthesized using two or more kinds of tetracarboxylic acids or two or more kinds of diamines. The fluorine atom or hydrocarbon group may be present in the repeating unit derived from tetracarboxylic acid, may be present in the repeating unit derived from diamine, or may be present in both repeating units. When introducing a hydrocarbon group into a polyimide, it is particularly preferable to form a steroid structure in the main chain or side chain of the polyimide. The steroid structure present in the side chain corresponds to a hydrocarbon group having 10 or more carbon atoms and has a function of vertically aligning the liquid crystalline compound. In this specification, the steroid structure is a cyclopentanohydrophenanthrene ring structure or a ring structure in which a part of the ring bond is a double bond in the range of an aliphatic ring (a range that does not form an aromatic ring). means.

  Further, as a means for vertically aligning the rod-like liquid crystal compound, a method of mixing an organic acid with a polymer of polyvinyl alcohol or polymide can be suitably used. As the acid to be mixed, carboxylic acid, sulfonic acid and amino acid are preferably used. You may use what shows the acidity among the below-mentioned air interface aligning agent. The mixing amount is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, based on the polymer.

(Air interface side vertical alignment agent)
Ordinary rod-like liquid crystalline compounds have the property of being tilted and oriented on the air interface side, so it is necessary to control the orientation of the rod-like liquid crystal compound vertically on the air interface side in order to obtain a uniformly vertically aligned state. It is. As the air interface side vertical alignment agent of the rod-like liquid crystal compound, the same compound as the air interface side vertical alignment agent of the discotic liquid crystal compound can be used, and the preferred range of the amount used is also the same. In addition, the compounds described in JP 2002-20363 A and JP 2002-129162 A can be used as the air interface side vertical alignment agent. Also, paragraph numbers 0072 to 0075 of Japanese Patent Application No. 2002-212100, paragraph numbers 0038 to 0040 and 0048 to 0049 of Japanese Patent Application No. 2002-243600, and paragraph numbers 0037 to 0039 of Japanese Patent Application No. 2002-262239. The matters described in Paragraph Nos. 0071 to 0078 of Japanese Patent Application No. 2003-91752 can also be appropriately applied to the present invention.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Accordingly, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Example 1]
<Preparation of IPS mode liquid crystal cell 1>
The electrodes shown in FIG. 1 were provided on a single glass substrate so that the distance between adjacent electrodes was 20 μm, and a polyimide film was provided as an alignment film thereon, and a rubbing treatment was performed. The rubbing process was performed in the direction shown in FIG. A polyimide film was provided on one surface of a separately prepared glass substrate, and a rubbing treatment was performed to obtain an alignment film. Two glass substrates are laminated and bonded so that the alignment films face each other, the distance between the substrates (gap; d) is 3.9 μm, and the rubbing directions of the two glass substrates are parallel. A nematic liquid crystal composition having a refractive index anisotropy (Δn) of 0.0769 and a dielectric anisotropy (Δε) of 4.5 was enclosed. The value of d · Δn of the liquid crystal layer was 300 nm.

<Preparation of optical compensation film 1>
(Production of first retardation region)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution having the following composition.
Composition of cellulose acetate solution Cellulose acetate with an acetylation degree of 60.9% 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Methylene chloride (first solvent) 300 Mass part Methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass In another mixing tank, 16 parts by mass of the following retardation increasing agent, 80 parts by mass of methylene chloride, and 20 parts by mass of methanol were added. Then, the mixture was stirred while heating to prepare a retardation increasing agent solution. A dope was prepared by mixing 7 parts by mass of the retardation increasing agent solution with 487 parts by mass of the cellulose acetate solution and stirring sufficiently.

  The obtained dope was cast using a band casting machine. After the film surface temperature on the band reached 40 ° C., the film was dried with warm air of 60 ° C. for 1 minute, and the film was peeled off from the band. Next, the film was dried with a drying air at 140 ° C. for 10 minutes to produce a cellulose acetate film 1 having a thickness of 80 μm.

  The optical properties of this film were determined by measuring the dependency of Re on the light incident angle using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments). Re = 8 nm, Rth = 82 nm there were.

(Production of second retardation region)
After the surface of the cellulose acetate film 1 was saponified, an alignment film coating solution having the following composition was applied onto the film with a wire bar coater at 20 ml / m ² . The film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds. Next, the formed film was rubbed in a direction parallel to the slow axis direction of the film to obtain an alignment film.
Composition of alignment film coating solution Polymer (AL-1) 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Triethylamine 0.5 parts by weight

  Next, 1.8 g of the following discotic liquid crystalline compound, 0.2 g of ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.), a photopolymerization initiator (IRGA) Cure 907, manufactured by Ciba Geigy Co., Ltd.) 0.06 g, sensitizer (Kaya Cure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.02 g, air interface side vertical alignment agent (fluorine polymer, compound P-15 below) 0.0072 g A solution of 3.9 g in methyl ethyl ketone (hereinafter referred to as a discotic liquid crystal composition) was applied with a wire bar # 3.4. This was affixed to a metal frame and heated in a thermostatic bath at 125 ° C. for 3 minutes to align the discotic liquid crystalline compound. Next, UV irradiation was performed for 30 seconds using a 120 W / cm high pressure mercury lamp at 100 ° C. to crosslink the discotic liquid crystalline compound. Then, it stood to cool to room temperature. Thus, the optical compensation film 1 was produced.

化合物Ｐ−１５

Compound P-15

  Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependency of Re of the optical compensation film 1 is measured, and the pre-measured contribution of the cellulose acetate film is subtracted. As a result, the optical characteristics of only the discotic liquid crystal layer were calculated. Re was 131 nm, Rth was −66 nm, the average tilt angle of the liquid crystal was 89.8 °, and the discotic liquid crystal was aligned perpendicular to the film surface. I was able to confirm. The slow axis direction was parallel to the rubbing direction of the alignment film.

  A polarizing film was produced by adsorbing iodine to a stretched polyvinyl alcohol film. Using the polyvinyl alcohol-based adhesive, the produced optical compensation film 1 was attached to one side of the polarizing film so that the cellulose acetate film was on the polarizing film side. The transmission axis of the polarizing film and the slow axis of the optical compensation film (the slow axis of the second retardation region also coincides with this) were arranged in parallel. A commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) was saponified and attached to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive. This is done so that the slow axis of the optical compensation film 1 is parallel to the rubbing direction of the liquid crystal cell on one of the IPS mode liquid crystal cells 1 produced above (that is, the slow axis of the second retardation region is The discotic liquid crystal application surface side was attached to the liquid crystal cell side so that it was parallel to the slow axis direction of the liquid crystal molecules during black display. Subsequently, a commercially available polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) was attached to the other side of the IPS mode liquid crystal cell 1 in a crossed Nicol arrangement to produce a liquid crystal display device.

<Measurement of leakage light of the manufactured liquid crystal display device>
The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 70 ° was 0.20%.

[Example 2]
In the production of the second retardation region of Example 1, alignment films using AL-2, AL-5, and AL-8, respectively, instead of AL-1 were produced as alignment films, and the same as in Example 1. A second retardation region was prepared, and optical compensation films 1-a, 1-b and 1-c were obtained in this order. A liquid crystal display device was manufactured in the same manner as in Example 1, and leakage light was measured when the liquid crystal display device was observed from the left oblique direction of 70 °. The results are shown in Table 2.

  As shown in Table 1, when the alignment film of the present invention is used, an optical compensation film in which the discotic liquid crystalline compound is vertically aligned is obtained in the same manner as in Example 1, and the optical compensation film IPS liquid crystal display device is obtained. As a result, a liquid crystal display device with little light leakage was obtained.

[Example 3]
<Preparation of optical compensation film 2>
Using a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., Re = 3 nm, Rth = 45 nm) as the first retardation region, the surface is saponified, The same alignment film coating solution as in Example 1 was applied at 20 ml / m ² with a wire bar coater. The film was dried with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds. Next, the formed film was rubbed in a direction parallel to the slow axis direction of the film.

  Subsequently, 1.8 g of the discotic liquid crystalline compound used in Example 1 and ethylene oxide-modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) were used on the alignment film prepared in Example 1. 0.2 g, photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 0.06 g, sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.02 g, air interface side vertical alignment agent (fluorine-containing compound) Then, a solution (liquid crystal composition) obtained by dissolving 0.0036 g of the following compound IV-48) in 3.9 g of methyl ethyl ketone was applied with a # 3 wire bar. This was affixed to a metal frame and heated in a thermostatic bath at 125 ° C. for 3 minutes to align the discotic liquid crystalline compound. Next, UV irradiation was performed for 30 seconds using a 120 W / cm high pressure mercury lamp at 100 ° C. to crosslink the discotic liquid crystalline compound. Then, it stood to cool to room temperature. Thus, the optical compensation film 2 was produced.

Compound IV-48

  Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependency of Re of the optical compensation film 2 is measured, and the pre-measured contribution of the cellulose acetate film is subtracted. Thus, the optical characteristics of only the discotic liquid crystal retardation layer were calculated. Re was 116 nm, Rth was −56 nm, the average tilt angle of the liquid crystal was 89.7 °, and the discotic liquid crystal was perpendicular to the film surface. It was confirmed that they were oriented. The slow axis direction was parallel to the rubbing direction of the alignment film.

  One of the IPS mode liquid crystal cells 1 produced above is placed on the optical compensation sheet 2 produced above so that its slow axis is parallel to the rubbing direction of the liquid crystal cell (that is, the slow phase of the second retardation region). The disc was adhered so that the axis was parallel to the slow axis direction of the liquid crystal molecules during black display) and the discotic liquid crystal application surface side was the liquid crystal cell side. Subsequently, a commercially available polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) is pasted on the optical compensation sheet 2 so that the transmission axis is parallel to the rubbing direction of the liquid crystal cell. The same polarizing plate was attached to the other side in a crossed Nicol arrangement to produce a liquid crystal display device.

(Measurement of leakage light of the manufactured liquid crystal display device)
The leakage light of the liquid crystal display device thus manufactured was measured. Light leakage when observed from the left oblique direction of 70 ° was 0.21%.

[Example 4]
<Production of Second Polarizing Plate 1>
Using a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd., Re = 3 nm, Rth = 45 nm), the surface was saponified, and a commercially available vertical alignment film (JALS- 204R, manufactured by Nippon Synthetic Rubber Co., Ltd. was diluted 1: 1 with methyl ethyl ketone, and then 2.4 ml / m ^{2 was} applied with a wire bar coater. Immediately, it was dried with warm air of 120 ° C. for 120 seconds.

(Formation of vertically aligned rod-like liquid crystal compound layer)
On the alignment film, 1.8 g of the following rod-like liquid crystal compound, 0.06 g of photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy), 0.02 g of sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) A solution prepared by dissolving 0.002 g of the air interface side vertical alignment agent in 9.2 g of methyl ethyl ketone was applied with a # 2 wire bar. This was attached to a metal frame and heated in a constant temperature bath at 100 ° C. for 2 minutes to align the rod-like liquid crystalline compound. Next, using a 120 W / cm high-pressure mercury lamp at 100 ° C., UV irradiation was performed for 30 seconds to crosslink the rod-like liquid crystalline compound. Then, it stood to cool to room temperature. In this way, a protective film 1 for the second polarizing plate was produced.

  Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependency of Re of the protective film 1 was measured. As a result, Re was 3 nm and Rth was 5 nm.

  Next, iodine is adsorbed to the stretched polyvinyl alcohol film to produce a polarizing film, and using the polyvinyl alcohol-based adhesive, the protective film 1 thus prepared is arranged on one side of the polarizing film so that the cellulose acetate film is on the polarizing film side. Pasted on. Subsequently, a commercially available cellulose acetate film (Fujitac TD80UF, manufactured by Fuji Photo Film Co., Ltd.) is subjected to saponification treatment, and is attached to the opposite side of the polarizing film using a polyvinyl alcohol adhesive. Formed. Further, in the same manner as in Example 1, the optical compensation film 1 was attached to one side of the polarizing film so that the cellulose acetate film was on the polarizing film side, and a commercially available cellulose acetate film was attached to the opposite side of the polarizing film. 1 is placed on one of the IPS mode liquid crystal cells 1 produced in Example 1 so that the slow axis of the optical compensation film 1 is parallel to the rubbing direction of the liquid crystal cell (that is, the second retardation region). The slow axis is parallel to the slow axis direction of the liquid crystal molecules during black display), and the discotic liquid crystal application surface side is pasted to the liquid crystal cell side. The transmission axis of this polarizing plate and the rubbing direction of the liquid crystal cell are parallel. Furthermore, a second polarizing plate is attached to the other side of the liquid crystal cell so that the transmission axis is perpendicular to the rubbing direction of the liquid crystal cell and the surface of the protective film 1 is on the liquid crystal cell side. Was made.

(Measurement of leakage light of the manufactured liquid crystal display device)
The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 70 ° was 0.07%.

[Comparative Example 1]
A commercially available polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) was attached to both sides of the produced IPS mode liquid crystal cell 1 in a crossed Nicol arrangement to produce a liquid crystal display device. An optical compensation film was not used. In the liquid crystal display device, as in Example 1, the polarizing plate was attached so that the transmission axis of the upper polarizing plate was parallel to the rubbing direction of the liquid crystal cell. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left diagonal direction of 70 ° was 0.55%.

[Comparative Example 2]
Compared to the IPS mode liquid crystal cell 1 produced in Example 1, the optical compensation sheet 2 produced in Example 3 is such that its slow axis is perpendicular to the rubbing direction of the liquid crystal cell and the discotic liquid crystal application surface side is liquid crystal Affixed to the cell side. Subsequently, a commercially available polarizing plate (HLC2-5618, manufactured by Sanritz Co., Ltd.) is attached on the optical compensation sheet 2 so that the transmission axis is parallel to the rubbing direction of the liquid crystal cell. The same polarizing plate was attached to the other side in a crossed Nicol arrangement to produce a liquid crystal display device. The leakage light of the liquid crystal display device thus manufactured was measured. The leakage light when observed from the left oblique direction of 70 ° was 1.52% and was extremely large.

[Comparative Example 3]
A liquid crystal display device was prepared and leakage light was measured in the same manner as in Example 1 except that the air interface side vertical alignment agent (P-15) was removed from the discotic liquid crystal composition in Example 1.
The light leakage when observed from the left diagonal direction of 70 ° was 1.2% and was extremely large.

It is the schematic which shows the pixel area example of the liquid crystal display device of this invention. It is the schematic which shows the example of the liquid crystal display device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal element pixel area 2 Pixel electrode 3 Display electrode 4 Rubbing direction 5a, 5b Director of liquid crystal compound at the time of black display 6a, 6b Director of liquid crystal compound at the time of white display 7a, 7b Protection for the first polarizing film Film 8 First polarizing film 9 Polarization transmission axis 10 of first polarizing film Optical compensation film 11 First retardation region 12 Second retardation region 13 Slow axis 14 of second retardation region First Substrate 15 First substrate rubbing direction 16 Liquid crystal layer 17 Slow axis direction 18 of liquid crystalline compound Second substrate 19 Second substrate rubbing directions 20a and 20b Second polarizing film protective film 21 Second polarizing film 22 Second polarizing film polarization transmission axis

Claims (15)

An alignment film for liquid crystal having at least one structural unit selected from the following general formula (I) and general formula (II) and at least one structural unit selected from general formula (III) and general formula (IV).
Formula (I)

(In the general formula (I), R ¹ represents a hydrogen atom, a methyl group, a halogen atom, or a cyano group, and L ¹¹ represents a single bond, an aliphatic group, a divalent aromatic group, a divalent heterocyclic group, or Represents a divalent linking group composed of a combination thereof, and P ¹¹ represents a divalent group composed of —O—, —NR ¹¹ —, —CO—, —S—, —SO— or —SO ₂ — or a combination thereof. R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, L ¹² represents a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof. X ¹ represents a hydrogen bonding group, and n1 represents an integer of 0 to 3. When n1 is 2 or more, each P ¹¹ and L ¹² are the same or different. May be.)
Formula (II)

(In the general formula (II), L ²¹ represents a single bond, an aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and P ²¹ represents —O —, —NR ²¹ —, —CO—, —S—, —SO—, —SO ₂ — or a combination thereof, represents a divalent linking group, and R ²¹ represents a hydrogen atom or a carbon number of 1-6. Represents an alkyl group, L ²² represents a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and X ² represents a hydrogen bonding group. N2 represents an integer of 0 to 3. When n2 is 2 or more, each P ²¹ and L ²² may be the same or different.
General formula (III)

(In the general formula (III), R ³ represents a hydrogen atom, a methyl group, a halogen atom or a cyano group, L ³¹ represents a single bond, a divalent aromatic group or a divalent heterocyclic group, and P ³¹ Represents a divalent linking group composed of —O—, —NR ³¹ —, —CO—, —S—, —SO— or —SO ₂ — or a combination thereof, and R ³¹ represents a hydrogen atom or a carbon number of 1; Represents an alkyl group of ˜6, L ³² represents a divalent linking group consisting of a single bond, a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and X ³ Represents an aliphatic group, an aromatic group, a heterocyclic group or a group thereof, and n3 represents an integer of 0 to 3. When n3 is 2 or more, each of P ³¹ and L ³² may be the same May be different.)
Formula (IV)

(In the general formula (IV), L ⁴¹ represents a divalent aromatic group or a divalent heterocyclic group, and P ⁴¹ represents —O—, —NR ⁴¹ —, —CO—, —S—, —SO—. Or -SO ₂ -or a divalent linking group composed of a combination thereof, R ⁴¹ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and L ⁴² represents a single bond or a divalent aliphatic group. Represents a divalent linking group comprising a divalent aromatic group, a divalent heterocyclic group or a combination thereof, and X ⁴ represents a group comprising an aliphatic group, an aromatic group, a heterocyclic group or a combination thereof. N4 represents an integer of 0 to 3. When n4 is 2 or more, P ⁴¹ and L ⁴² may be the same or different. The structural unit represented by the general formula (I), wherein R ¹ is a hydrogen atom or a methyl group, and L ¹¹ is a single bond, a divalent aromatic group or a divalent heterocyclic group. Or a divalent linking group composed of a combination thereof, and P ¹¹ is a divalent linking group composed of —O—, —NR ¹¹ —, —CO— or —SO ₂ — or a combination thereof; ^The alignment film for liquid crystal according to claim 1, wherein ¹¹ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n1 is an integer of 1 to 3. The structural unit represented by the general formula (III), P ³¹ is —COO— or —CONR ³¹ —, and R ³¹ is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. The alignment film for liquid crystal according to claim 1 or 2. The structural unit represented by the general formula (III), and the L ³¹ is a divalent linking group comprising a single bond, a divalent aromatic group, a divalent heterocyclic group or a combination thereof. The liquid crystal alignment film according to claim 1, wherein L ³² is a divalent linking group comprising a divalent aromatic group, a divalent heterocyclic group, or a combination thereof. A retardation film obtained by aligning and fixing a discotic liquid crystalline compound on the alignment film for liquid crystal according to any one of claims 1 to 4. The surface of the alignment film for liquid crystal is rubbed, and a liquid crystal composition containing the discotic liquid crystalline compound is applied and aligned on the surface of the alignment film for liquid crystal thus treated. The retardation film described. The retardation film according to claim 6, wherein the liquid crystal composition contains at least one additive that makes the discotic liquid crystal compound substantially vertically aligned. A first polarizing film;
An optical compensation film having a first retardation region provided on the first polarizing film and a second retardation region provided in contact with the first retardation region;
A first substrate provided on the second retardation region side of the optical compensation film; a second substrate provided opposite to the first substrate; the first substrate; A liquid crystal layer made of a nematic liquid crystal material provided between two substrates,
And the liquid crystal display device in which the liquid crystalline compound of the nematic liquid crystal material is aligned in parallel with the surfaces of the first substrate and the second substrate during black display,
The first retardation region has an in-plane retardation (Re) represented by the following formula (1) of 20 nm or less, and a thickness direction retardation (Rth) represented by the following formula (2). 20 nm to 120 nm,
The second retardation region has an optically anisotropic layer having the retardation film according to any one of claims 5 to 7,
The liquid crystal display device, wherein a delay axis of the second retardation region is parallel to a transmission axis of the first polarizing film and a slow axis direction of a liquid crystal compound during black display.
Expression (1) Re = (nx−ny) × d
Formula (2) Rth = ((nx + ny) / 2−nz) × d
(In the formula (1) and the formula (2), nx and ny represent the refractive index in the film (nx ≧ ny), nz represents the refractive index in the thickness direction of the film, and d represents the film Represents thickness.) The liquid crystal display device according to claim 8, further comprising a second polarizing film on the second substrate. The liquid crystal display device according to claim 8 or 9, wherein Re of the second retardation region is 50 nm to 200 nm. The first retardation region is composed of a plurality of layers, and at least one layer in contact with the second retardation region among the plurality of layers is according to any one of claims 1 to 4. The liquid crystal display device according to claim 8, wherein the liquid crystal display device is an alignment film. The said 2nd polarizing film has a protective film on the film | membrane surface at the side close | similar to the said liquid-crystal layer at least, and this protective film has Rth of 20 nm or less. Liquid crystal display device. The liquid crystal display device according to claim 12, wherein the protective film is a cellulose acylate film or a norbornene-based film. The liquid crystal display device according to claim 12, wherein the protective film has a cellulose acylate film and a layer containing a vertically aligned rod-like liquid crystal compound. The first polarizing film has a protective film on at least a film surface close to the first retardation region, and the first retardation region is composed of a plurality of layers, The liquid crystal display device according to claim 8, wherein one of the plurality of layers also serves as a protective film for the first polarizing film.

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