JP2006259129A - Optical compensation sheet, liquid crystal display device using the same, and method of manufacturing optical compensation sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical compensation sheet which is free from a defect such as a schlieren defect and wherein alignment of a liquid crystalline compound is precisely controlled. <P>SOLUTION: The optical compensation sheet has an optical anisotropic layer on a supporting body. The optical anisotropic layer contains at least one liquid crystal compound and a polymer containing a fluoroaliphatic group having a photo-reactive group. The optical compensation sheet is obtained by irradiating the optical anisotropic layer with light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel optical compensation sheet, a method for producing the optical compensation sheet, and a liquid crystal display device.

Optical compensation sheets are used in various liquid crystal display devices in order to eliminate image coloring and expand the viewing angle. Conventionally, stretched birefringent films have been used as optical compensation sheets.In recent years, instead of stretched birefringent films, optical compensation sheets having an optically anisotropic layer made of a discotic liquid crystalline compound on a support are used. It is proposed to use. In this optically anisotropic layer, a composition containing a discotic liquid crystalline compound is usually applied on an alignment film, and heated to a temperature higher than the alignment temperature to align the discotic liquid crystalline compound, and the alignment state is changed. It is formed by fixing.
In general, the discotic liquid crystalline compound has a large birefringence and various alignment forms. By using a discotic liquid crystalline compound, it has become possible to realize optical properties that cannot be obtained with conventional stretched birefringent films.

  On the other hand, since various orientation forms exist in the discotic liquid crystalline compound, it is necessary to control the orientation of the discotic liquid crystalline compound in the optically anisotropic layer in order to develop desired optical characteristics. In particular, to achieve optical compensation performance, it is important to realize a so-called “hybrid alignment” state in which the tilt angle of the discotic liquid crystalline compound is aligned so as to change with the distance from the support surface. It is the most important factor that determines the performance of the compensation sheet, that is, the viewing angle expansion, the contrast reduction due to the viewing angle change, the gradation inversion, the black-and-white inversion, and the hue change. This hybrid alignment is the difference between the tilt angle of the alignment film surface provided on the support for the purpose of regulating the orientation angle of the discotic liquid crystalline compound and the tilt angle of the air-side interface that is the outermost surface of the optical compensation sheet. It is realized by using. After applying and drying the optical compensation sheet using the discotic liquid crystalline compound, the discotic liquid crystalline compound is monodomain aligned at a stable tilt angle at both the air interface and the alignment film interface. As a result, an alignment state in which the tilt angle continuously changes in the thickness direction of the film is formed. The discotic liquid crystalline compound has a property of having a high tilt angle of 50 ° or more at the air interface. Therefore, in order to realize the hybrid alignment, the tilt angle at the alignment film interface must be significantly smaller than the tilt angle at the air interface. An alignment film using polyvinyl alcohol is suitably used for realizing the target hybrid alignment because the tilt angle is close to 0 ° (see, for example, Patent Document 1).

  On the other hand, in order to obtain a desired optical compensation function, it is necessary to precisely control the tilt angle on the air interface side. As a method of obtaining an angle exceeding 50 ° which is a tilt angle obtained at a normal air interface, a method of adding a partially esterified cellulose (for example, see Patent Document 2) or a fluorine-substituted alkyl group and a hydrophilic group (a sulfo group is a linking group) There has been proposed a method of adding a compound having a bond to a benzene ring via (see, for example, Patent Document 3). However, when the present inventors actually used these optical compensation sheets, light leakage from the oblique direction of the polarizing plate was observed, and the viewing angle did not expand sufficiently (to the extent that could be expected theoretically). It turns out that there is also. One reason for the insufficient optical compensation function may be that the tilt angle of the discotic liquid crystalline compound is not sufficiently controlled.

  Furthermore, in these methods, since the discotic liquid crystalline compound cannot be uniformly regulated in the azimuth direction at the air interface, regions having different azimuth directions are generated, and alignment defects (Schlieren defects) are likely to occur as a result. Form a state. When a schlieren defect occurs in the optically anisotropic layer, there is a problem that light scattering occurs and optical properties are impaired. Schlieren defects are eliminated over time by changing the azimuthal direction of the alignment so that the discotic liquid crystalline compound cancels the defects if the liquid crystal state is maintained by temperature control and sufficient aging time is given. In particular, it becomes monodomain to achieve defect-free hybrid orientation. For this reason, if the ripening time is shortened for the purpose of manufacturing efficiency, there is a problem that the occurrence of schlieren defects tends to become remarkable, and it is necessary to develop a technique that can shorten the monodomainization time. In particular, when the above compound is added to increase the tilt angle on the air interface side in order to obtain the desired optical performance, the defect disappearance rate is significantly delayed, resulting in extremely inefficient manufacturing. Therefore, there has been a strong demand for the development of a technology that can efficiently promote the hybrid alignment of liquid crystal compounds and precisely control the tilt angle of the air interface.

Here, as an alignment control method other than rubbing, a photo-alignment technique using light is known, and a polymer substituted with an azo group is used as an alignment film of a discotic liquid crystalline compound, and this is irradiated with light. Thus, a technique for imparting orientation has already been disclosed (for example, Patent Document 4). However, even if the tilt angle of the alignment film interface can be controlled by this method, it is difficult to efficiently promote the hybrid alignment and to precisely control the tilt angle of the air interface, which are the aforementioned problems.
Moreover, the low molecular weight compound containing a fluoro aliphatic group is disclosed as an orientation control agent of a liquid crystalline compound (patent document 5). However, with such a fluoroaliphatic group-containing low molecular weight compound, it is difficult to sufficiently control the tilt angle when the alignment ripening time is short.

JP-A-8-50206 JP-A-8-95030 JP 2001-330725 A JP 10-278123 A JP 2002-38157 A

  An object of the present invention is to provide a manufacturing method suitable for rapid and mass production of an optical compensation sheet that is free from defects such as schlieren defects and in which the orientation angle of a liquid crystal compound is precisely controlled. Another object of the present invention is to provide an optical compensation sheet having high optical uniformity and an excellent optical compensation function. It is another object of the present invention to provide a liquid crystal display device using the optical compensation sheet.

（一般式（１）中、Ｒ¹は水素原子または置換基を表し、Ｌ¹は単結合または２価の連結基を表し、Ａは光反応性基を表す。また、Ｙ¹は−ＮＲ^a−（Ｒ^aは炭素原子数１〜５のアルキル基または水素原子を表す。）または−Ｏ−を表す。）
一般式（２）

（一般式（２）中、Ｒ²は水素原子または置換基を表し、Ｌ²は単結合または２価の連結基を表し、Ｒｆは一部または全部がフッ素原子で置換されたアルキル基を表す。Ｙ²は−ＮＲ^a−（Ｒ^aは炭素原子数が１〜５のアルキル基または水素原子を表す。）または−Ｏ−を表す。）
（３）前記光照射は、単一方向からの光照射である、（１）または（２）に記載の光学補償シート。
（４）前記光学補償シートは、配向膜を有し、該配向膜の配向機能を、ラビング処理、単一方向からの非偏光照射、または単一方向からの偏光照射によって付与してなる、（１）〜（３）のいずれかに記載の光学補償シート。
（５）前記少なくとも１種の液晶性化合物がディスコティック液晶性化合物である、（１）〜（４）のいずれかに記載の光学補償シート。
（６）前記ディスコティック液晶性化合物がハイブリッド配向で固定されている、（１）〜（５）のいずれかに記載の光学補償シート。
（７）（１）〜（６）のいずれかに記載の光学補償シートを有することを特徴とする、液晶表示装置。
（８）支持体上に配向膜と光学異方性層とを有する光学補償シートの製造方法であって、前記光学異方性層が少なくとも１種の液晶化合物および光反応性基を有するフルオロ脂肪族基含有ポリマーを含有し、該光学異方性層に光照射を行うことを特徴とする前記光学補償シートの製造方法。 Means for solving the above problems are as follows.
(1) An optical compensation sheet having an optically anisotropic layer on a support, wherein the optically anisotropic layer contains at least one liquid crystal compound and a fluoroaliphatic group-containing polymer having a photoreactive group. The optical compensation sheet obtained by irradiating the optically anisotropic layer with light.
(2) The fluoroaliphatic group-containing polymer having a photoreactive group is a repeating unit derived from at least one monomer represented by the following general formula (1), and a monomer represented by the following general formula (2) The optical compensation sheet according to (1), which is a copolymer containing a repeating unit derived from at least one of the above.
General formula (1)

(In General Formula (1), R ¹ represents a hydrogen atom or a substituent, L ¹ represents a single bond or a divalent linking group, A represents a photoreactive group, and Y ¹ represents —NR ^a. — (R ^a represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom) or —O—.
General formula (2)

(In General Formula (2), R ² represents a hydrogen atom or a substituent, L ² represents a single bond or a divalent linking group, and Rf represents an alkyl group partially or entirely substituted with a fluorine atom. Y ² represents —NR ^a — (R ^a represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom) or —O—.
(3) The optical compensation sheet according to (1) or (2), wherein the light irradiation is light irradiation from a single direction.
(4) The optical compensation sheet has an alignment film, and the alignment function of the alignment film is imparted by rubbing treatment, non-polarized light irradiation from a single direction, or polarized light irradiation from a single direction. The optical compensation sheet according to any one of 1) to (3).
(5) The optical compensation sheet according to any one of (1) to (4), wherein the at least one liquid crystalline compound is a discotic liquid crystalline compound.
(6) The optical compensation sheet according to any one of (1) to (5), wherein the discotic liquid crystalline compound is fixed in a hybrid orientation.
(7) A liquid crystal display device comprising the optical compensation sheet according to any one of (1) to (6).
(8) A method for producing an optical compensation sheet having an alignment film and an optically anisotropic layer on a support, wherein the optically anisotropic layer has at least one liquid crystal compound and a photoreactive group. A method for producing an optical compensation sheet, comprising a group group-containing polymer and irradiating the optically anisotropic layer with light.

  The optical compensation sheet of the present invention is an optical compensation sheet in which the tilt angle is precisely controlled even when the alignment aging time is short as compared with the conventional optical compensation sheet.

BEST MODE FOR CARRYING OUT THE INVENTION

  Hereinafter, the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

  The optical compensation sheet of the present invention is characterized in that the optically anisotropic layer contains a fluoroaliphatic group-containing polymer having a photoreactive group. By using a fluoroaliphatic group-containing polymer having a photoreactive group as a photoalignment material, it is possible to impart alignment ability on the air interface side of the liquid crystalline compound by irradiating the optically anisotropic layer with light. Thereby, it is possible to obtain an optical compensation sheet that is free from defects such as schlieren defects, has high optical uniformity, and the orientation of the liquid crystalline compound is precisely controlled.

1-1. Air interface alignment controller (fluoroaliphatic group-containing polymer having photoreactive groups)
In the present invention, the fluoroaliphatic group-containing polymer used as the air interface alignment controller of the liquid crystalline compound has a photoreactive group. The photoreactive group is, for example, a functional group capable of orienting a liquid crystalline compound due to a change in the chemical structure of the functional group or the orientation state of the molecule having the functional group by light irradiation from a single direction. Refers to the group. Specifically, azobenzene derivatives, cinnamic acid derivatives, chalcone derivatives, stilbenes, styrylpyridine derivatives, α-hydrazono-β-ketoesters, coumarin derivatives, benzylidenephthalimidines, retinoic acid derivatives, spiropyrans, spirooxazines , Anthracene derivatives, benzophenone derivatives, polyimide and the like. Of these, preferred are a coumarin derivative, a styrylpyridine derivative, an azobenzene derivative, a cinnamic acid derivative and a chalcone derivative, and more preferred are an azobenzene derivative, a cinnamic acid derivative and a chalcone derivative.

The fluoroaliphatic group is an alkyl group substituted with a fluorine atom, and the substitution rate of the fluorine atom is such that 50% or more of the hydrogen atoms contained in the alkyl group are substituted with a fluorine atom. Preferably, 60% or more is more preferably substituted. Preferably terminal functional groups are CF ₃ group or CF ₂ H group, and particularly preferably a CF ₃ group.

  One of the fluoroaliphatic groups in the fluoropolymer according to the present invention is derived from a fluoroaliphatic compound produced by a telomerization method (also referred to as a telomer method) or an oligomerization method (also referred to as an oligomer method). It is. Regarding the production method of these fluoroaliphatic compounds, for example, “Synthesis and function of fluorine compounds” (supervision: Nobuo Ishikawa, published by CMC Co., 1987), “Chemistry of Organic Fluorine Compounds” II "(Monograph 187, Ed by Milos Hudlicky and Attila E. Pavlath, American Chemical Society 1995), pages 747-752. The telomerization method is a method of synthesizing a telomer by radical polymerization of a fluorine-containing vinyl compound such as tetrafluoroethylene using an alkyl halide having a large chain transfer constant such as iodide as a telogen (example in Scheme-1). showed that).

  The obtained terminal iodinated telomer is usually subjected to appropriate terminal chemical modification such as [Scheme2], and led to a fluoroaliphatic compound. These compounds are further converted into a desired monomer structure as necessary, and used for the production of a fluoroaliphatic group-containing polymer.

  In addition, as the type of the polymer, any of the polymer types described in “Revised Chemistry of Polymer Synthesis” (Takayuki Otsu, published by Kagaku Dojin Co., 1968), pages 1 to 4, For example, polyolefins, polyesters, polyamides, polyimides, polyurethanes, polycarbonates, polysulfones, polycarbonates, polyethers, polyacetals, polyketones, polyphenylene oxides, polyphenylene sulfides, polyarylates, four Examples thereof include fluorinated ethylene (PTFE), polyvinylidene fluoride, and cellulose derivatives. The fluoroaliphatic group-containing polymer is preferably a polyolefin.

（一般式（１）中、Ｒ¹は水素原子または置換基を表し、Ｌ¹は単結合または２価の連結基を表し、Ａは光反応性基を表す。また、Ｙ¹は−ＮＲ^a−（Ｒ^aは炭素原子数１〜５のアルキル基または水素原子を表す。）または−Ｏ−を表す。）

（一般式（２）中、Ｒ²は水素原子または置換基を表し、Ｌ²は単結合または２価の連結基を表し、Ｒｆは一部または全部がフッ素原子で置換されたアルキル基を表す。Ｙ²は−ＮＲ^a−（Ｒ^aは炭素原子数が１〜５のアルキル基または水素原子を表す。）または−Ｏ−を表す。） Examples of the fluoroaliphatic group-containing polymer having a photoreactive group include a repeating unit derived from at least one monomer represented by the following general formula (1) and a monomer represented by the following general formula (2). A copolymer containing a repeating unit derived from at least one kind is preferably used.

(In General Formula (1), R ¹ represents a hydrogen atom or a substituent, L ¹ represents a single bond or a divalent linking group, A represents a photoreactive group, and Y ¹ represents —NR ^a. — (R ^a represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom) or —O—.

(In General Formula (2), R ² represents a hydrogen atom or a substituent, L ² represents a single bond or a divalent linking group, and Rf represents an alkyl group partially or entirely substituted with a fluorine atom. Y ² represents —NR ^a — (R ^a represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom) or —O—.

The substituent represented by R ¹ in the general formula (1) or the substituent represented by R ² in the general formula (2) represents a substituent selected from the substituent group exemplified below. .
(Substituent group)
Examples of the substituent group include an alkyl group (preferably an alkyl group having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, and particularly preferably 1 to 8 carbon atoms, such as a methyl group, an ethyl group, and an isopropyl group. Group, tert-butyl group, n-octyl group, n-decyl group, n-hexadecyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group and the like, alkenyl group (preferably having 2 to 20 carbon atoms, more preferably). Is an alkenyl group having 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, and examples thereof include a vinyl group, an aryl group, a 2-butenyl group and a 3-pentenyl group, and an alkynyl group (preferably a carbon atom). An alkynyl group having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, such as a propargyl group, 3 A pentynyl group), an aryl group (preferably an aryl group having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, and particularly preferably 6 to 12 carbon atoms, such as a phenyl group and p-methyl group). A phenyl group, a naphthyl group, etc.), a substituted or unsubstituted amino group (preferably a carbon number of 0-20, more preferably a carbon number of 0-10, particularly preferably a carbon number of 0-6, For example, an unsubstituted amino group, a methylamino group, a dimethylamino group, a diethylamino group, an anilino group, etc.)

An alkoxy group (preferably having 1 to 20 carbon atoms, such as a methoxy group, an ethoxy group or a butoxy group), an alkoxycarbonyl group (preferably having 2 to 20 carbon atoms, more preferably having 2 to 16 carbon atoms, Particularly preferably, it is 2 to 10, for example, methoxycarbonyl group, ethoxycarbonyl group and the like, acyloxy group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms). For example, an acetoxy group, a benzoyloxy group, etc.), an acylamino group (preferably an acylamino group having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, and particularly preferably 2 to 10 carbon atoms). Acetylamino group, benzoylamino group, etc.), alkoxycarbonylamino group ( Preferably an alkoxycarbonylamino group having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as a methoxycarbonylamino group), aryloxycarbonylamino A group (preferably an aryloxycarbonylamino group having 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as a phenyloxycarbonylamino group), a sulfonyl An amino group (preferably a sulfonylamino group having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, and particularly preferably 1 to 12 carbon atoms, and examples thereof include a methanesulfonylamino group and a benzenesulfonylamino group. ), A sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably A sulfamoyl group having a prime number of 0 to 16, particularly preferably 0 to 12 carbon atoms, and examples thereof include a sulfamoyl group, a methylsulfamoyl group, a dimethylsulfamoyl group, and a phenylsulfamoyl group), a carbamoyl group ( Preferably it is C1-C20, More preferably, it is C1-C16, Most preferably, it is C1-C12 carbamoyl group, for example, unsubstituted carbamoyl group, methylcarbamoyl group, diethylcarbamoyl group, phenylcarbamoyl group Etc.),

An alkylthio group (preferably an alkylthio group having 1 to 20 carbon atoms, more preferably an alkylthio group having 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as a methylthio group and an ethylthio group), an arylthio group ( Preferably it is C6-C20, More preferably, it is C6-C16, Most preferably, it is C6-C12 arylthio group, for example, a phenylthio group etc. are mentioned, A sulfonyl group (preferably C1-C1). 20, more preferably a sulfonyl group having 1 to 16 carbon atoms, particularly preferably a sulfonyl group having 1 to 12 carbon atoms, such as a mesyl group and a tosyl group, and a sulfinyl group (preferably having a carbon number of 1 to 20, more A sulfinyl group having 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms is preferable. Zensulfinyl group and the like), ureido group (preferably a ureido group having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms, for example, an unsubstituted ureido group , Methylureido group, phenylureido group, etc.), phosphoric acid amide group (preferably having 1 to 20 carbon atoms, more preferably having 1 to 16 carbon atoms, particularly preferably having 1 to 12 carbon atoms). Yes, for example, diethyl phosphoric acid amide group, phenyl phosphoric acid amide group, etc.), hydroxy group, mercapto group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, Carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (preferably having a carbon number of 1 to 0, more preferably a heterocyclic group of 1 to 12, for example, a heterocyclic group having a heteroatom such as a nitrogen atom, an oxygen atom, a sulfur atom, such as an imidazolyl group, a pyridyl group, a quinolyl group, a furyl group , Piperidyl group, morpholino group, benzoxazolyl group, benzimidazolyl group, benzthiazolyl group and the like), silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably A silyl group having 3 to 24 carbon atoms, and examples thereof include a trimethylsilyl group and a triphenylsilyl group).
These substituents may be further substituted with these substituents. Further, when two or more substituents are present, they may be the same or different. If possible, they may be bonded to each other to form a ring.

In the general formula (1) or the general formula (2), R ¹ or R ² is preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Each is preferably a hydrogen atom or a methyl group.

In the general formula (1) or the general formula (2), L ^{1 and} L ² each represent a single bond or a divalent linking group. In the case of a divalent linking group, an alkylene group, an alkenylene group, a divalent aromatic group, a divalent heterocyclic residue, -CO-, -NR ^a- (R ^a has 1 to And a divalent linking group selected from the group consisting of —O—, —S—, —SO—, —SO ₂ — and combinations thereof. The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The number of carbon atoms in the arylene group is preferably 6-10. The alkylene group, alkenylene group and arylene group may be substituted with an alkyl group, a halogen atom, a cyano group, an alkoxy group, an acyloxy group or the like, if possible. L ¹ in the general formula (1) includes a single bond, —O—, —CO—, —NR ^a — (R ^a is an alkyl group having 1 to 5 carbon atoms or a hydrogen atom) or an alkylene group. It is particularly preferable that it contains a single bond, —O—, or an alkylene group. L ¹ or L ² may be the same or different.

Specific examples of L ¹ or L ² are shown below, but the present invention is not limited to these specific examples. Moreover, the combination of the following specific example is also preferable. In specific examples, L ¹ is preferably L-1 to L-12, and more preferably L-1, L-2, L-4, L-7 to L-12. In specific examples, L ² is preferably a combination of two or more of L-1, L-19, L-20, or L-19.

  A in the general formula (1) is a photoreactive group, preferably a coumarin derivative, a styrylpyridine derivative, an azobenzene derivative, a cinnamic acid derivative or a chalcone derivative, more preferably an azobenzene derivative, cinnamic acid derivative or chalcone. Is a derivative.

  In the general formula (2), the alkyl group substituted with a fluorine atom represented by Rf may have a cyclic structure or a branched structure. The number of carbon atoms is preferably 1-20, more preferably 4-16, and even more preferably 4-12.

In the alkyl group substituted with a fluorine atom represented by Rf, the substitution rate of the fluorine atom is preferably such that 50% or more of the hydrogen atoms contained in the alkyl group are substituted with a fluorine atom, and 60% or more are substituted. More preferably. Rf is preferably terminated with a CF ₃ group or a CF ₂ H group, more preferably a CF ₃ group.
Incidentally, the fluoroaliphatic group-containing polymer having a photoreactive group in the present invention is composed of only one kind of the monomer represented by the general formula (1) and the monomer represented by the general formula (2). Alternatively, one or both of them may be composed of two or more.

  Although the specific example of the monomer which comprises the repeating unit which has a photoreactive group represented by General formula (1) below is given, this invention is not restrict | limited to the following specific examples.

  Specific examples of the monomer represented by the general formula (2) are given below, but the present invention is not limited to the following specific examples.

  In the fluoroaliphatic group-containing polymer having a photoreactive group in the present invention, the amount of the monomer represented by the general formula (1) is preferably 30% by mass or more of the total amount of monomers constituting the polymer. More preferably, it is at least 50% by mass, and even more preferably at least 50% by mass. In the fluoroaliphatic group-containing polymer, the amount of the monomer represented by the general formula (2) is preferably 5 to 50% by mass of the total amount of monomers constituting the polymer.

  The mass average molecular weight of the fluoroaliphatic group-containing polymer having a photoreactive group in the present invention is preferably 1,000 to 1,000,000, more preferably 1,000 to 500,000. More preferably, it is from 100,000 to 100,000. The mass average molecular weight can be measured as a value in terms of polystyrene (PS) using gel permeation chromatography (GPC).

  The polymerization method of the fluoroaliphatic group-containing polymer having a photoreactive group in the present invention is not particularly limited. For example, polymerization methods such as cationic polymerization, radical polymerization, or anionic polymerization using a vinyl group Among these, radical polymerization can be used for general purposes, and is particularly preferable. As the polymerization initiator for radical polymerization, known compounds such as radical thermal polymerization initiators and radical photopolymerization initiators can be used, and it is particularly preferable to use radical thermal polymerization initiators. Here, the radical thermal polymerization initiator is a compound that generates radicals by heating to a decomposition temperature or higher. Examples of such radical thermal polymerization initiators include diacyl peroxide (acetyl peroxide, benzoyl peroxide, etc.), ketone peroxide (methyl ethyl ketone peroxide, cyclohexanone peroxide, etc.), hydroperoxide (hydrogen peroxide, tert- Butyl hydroperoxide, cumene hydroperoxide, etc.), dialkyl peroxides (di-tert-butyl peroxide, dicumyl peroxide, dilauroyl peroxide, etc.) peroxyesters (tert-butyl peroxyacetate, tert-butyl) Peroxypivalate, etc.), azo compounds (azobisisobutyronitrile, azobisisovaleronitrile, etc.), persulfates (ammonium persulfate, sodium persulfate, potassium persulfate) Umm, etc.) and the like. Such radical thermal polymerization initiators can be used alone or in combination of two or more.

  The radical polymerization method is not particularly limited, and an emulsion polymerization method, suspension polymerization method, bulk polymerization method, solution polymerization method and the like can be employed. Solution polymerization, which is a typical radical polymerization method, will be described more specifically. The outlines of other polymerization methods are the same, and details thereof are described in, for example, “Polymer Chemistry Experimental Methods” edited by Polymer Society (Tokyo Kagaku Dojin, 1981).

  An organic solvent is used to perform the solution polymerization. These organic solvents can be arbitrarily selected as long as the objects and effects of the present invention are not impaired. These organic solvents are usually organic compounds having a boiling point in the range of 50 to 200 ° C. under atmospheric pressure, and organic solvents that uniformly dissolve each component are desirable. Examples of preferable organic solvents include alcohols such as isopropanol and butanol, ethers such as dibutyl ether, ethylene glycol dimethyl ether, tetrahydrofuran and dioxane, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, ethyl acetate and acetic acid. Examples thereof include esters such as butyl, amyl acetate and γ-butyrolactone, and aromatic hydrocarbons such as benzene, toluene and xylene. In addition, these organic solvents can be used individually by 1 type or in combination of 2 or more types. Furthermore, a water-mixed organic solvent in which water is used in combination with the above organic solvent is also applicable from the viewpoint of the solubility of the monomer and the polymer to be produced.

  Further, the solution polymerization conditions are not particularly limited, but for example, it is desirable to heat within a temperature range of 50 to 200 ° C. for 10 minutes to 30 hours. Furthermore, it is desirable to perform an inert gas purge not only during solution polymerization but also before the start of solution polymerization so that the generated radicals are not deactivated. Usually, nitrogen gas is suitably used as the inert gas.

  In order to obtain the fluoroaliphatic group-containing polymer having a photoreactive group in the present invention within a preferable molecular weight range, a radical polymerization method using a chain transfer agent is particularly effective. Examples of the chain transfer agent include mercaptans (for example, octyl mercaptan, decyl mercaptan, dodecyl mercaptan, tert-dodecyl mercaptan, octadecyl mercaptan, thiophenol, p-nonylthiophenol, etc.), polyhalogenated alkyls (for example, carbon tetrachloride). , Chloroform, 1,1,1-trichloroethane, 1,1,1-tribromooctane, etc.) and low-activity monomers (α-methylstyrene, α-methylstyrene dimer, etc.) can be used, but preferably Is a mercaptan having 4 to 16 carbon atoms. The amount of these chain transfer agents to be used is significantly affected by the activity of the chain transfer agent, the combination of the monomers, the polymerization conditions, and the like, and requires precise control, but is usually 0 with respect to the total number of moles of monomers used. It is about 0.01 mol% to 50 mol%, preferably 0.05 mol% to 30 mol%, particularly preferably 0.08 mol% to 25 mol%. These chain transfer agents may be present in the system simultaneously with the target monomer whose degree of polymerization is to be controlled in the polymerization process, and the addition method is not particularly limited. It may be added after being dissolved in the monomer, or may be added separately from the monomer.

  Specific examples of the fluoroaliphatic group-containing polymer having a photoreactive group used in the present invention are shown below, but the compound used in the present invention is not limited thereto. In addition, the number in a formula shows the mass percentage of each monomer component. Mw represents a mass average molecular weight.

  The addition amount of the fluoroaliphatic group-containing polymer having a photoreactive group is preferably 0.01 to 20% by mass, more preferably 0.05 to 10% by mass, more preferably 0.05 to 1% by mass is most preferred. In this invention, 1 type of the fluoro aliphatic group containing polymer which has the said photoreactive group may be used, and 2 or more types may be used.

  In the optical compensation sheet of the present invention, the fluoroaliphatic group-containing polymer having the photoreactive group is irradiated with light, thereby imparting an alignment regulating force on the air interface side of the liquid crystalline compound. As a light irradiation method, it is preferable that the film (optically anisotropic layer) is irradiated with light from a single direction. In this case, X-rays, electron beams, ultraviolet rays, visible rays or infrared rays (heat rays) are used as the irradiation light, and it is particularly preferable to use ultraviolet rays. The wavelength of the ultraviolet light is preferably 400 nm or less, and more preferably 250 nm to 360 nm. As the light source, a low-pressure mercury lamp, a high-pressure discharge lamp, or a short arc discharge lamp is preferably used.

  It is preferable to irradiate the film with light aligned in a single direction as much as possible. This “single direction” means a single direction in the film plane (direction in which the direction of light is projected onto the film plane), and includes a direction horizontal or perpendicular to the film plane. However, it is preferable to irradiate from an oblique direction with respect to the film plane. The irradiation direction can be adjusted according to the direction in which the discotic liquid crystal compound is desired to be aligned. The light irradiation may be either non-polarized light irradiation or polarized light irradiation.

The light used in the present invention may be linearly polarized light or non-polarized light. Irradiation dose is preferably ^{10mJ / cm 2 ~30000mJ / cm 2} , further preferably ^{20mJ / cm 2 ~6000mJ / cm 2} .

1-2. Liquid crystalline compound Examples of the liquid crystalline compound used for the optically anisotropic layer include a rod-like liquid crystalline compound or a discotic liquid crystalline compound. The rod-like liquid crystalline compound or the discotic liquid crystalline compound may be a high molecular liquid crystalline compound or a low molecular liquid crystalline compound, and further includes those in which the low molecular liquid crystalline compound is cross-linked and no longer exhibits liquid crystallinity. A rod-like liquid crystal compound and a discotic liquid crystal compound may be used in combination. More preferably, it is a discotic liquid crystalline compound.

[Bar-shaped liquid crystalline compound]
Examples of rod-like liquid crystalline compounds 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. The rod-like liquid crystalline compound includes a metal complex. Moreover, the liquid crystal polymer which contains a rod-shaped liquid crystalline compound in a repeating unit can also be used as a rod-shaped liquid crystalline compound. In other words, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer. For rod-like liquid crystalline compounds, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemical Review Vol. 22 Liquid Crystal Chemistry (1994) edited by the Chemical Society of Japan, and the 142nd Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.
The birefringence of the rod-like liquid crystalline compound is preferably in the range of 0.001 to 0.7. The rod-like liquid crystalline compound preferably has a polymerizable group in order to fix the alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable group described in paragraphs [0064] to [0086] of JP-A-2002-62427. And polymerizable liquid crystal compounds.

[Discotic liquid crystalline compounds]
Examples of discotic liquid crystalline compounds include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

  As a discotic liquid crystalline compound, a compound having liquid crystallinity in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. The optically anisotropic layer formed from the discotic liquid crystalline compound does not necessarily require that the compound finally contained in the optically anisotropic layer is a discotic liquid crystalline compound. Also included are compounds that have a group that reacts with heat or light, and that eventually polymerize or cross-link by reaction with heat or light to increase the molecular weight and lose liquid crystallinity. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. Moreover, about superposition | polymerization of a discotic liquid crystalline compound, Unexamined-Japanese-Patent No. 8-27284 has description.

  In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, and the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraph numbers [0151] to [0168] in JP-A No. 2000-155216.

In the production method of the present invention, the aging time of the discotic liquid crystalline compound can be about 30 to 60 seconds. As a result, the manufacturing time can be shortened.
In hybrid alignment, the angle between the long axis (disk surface) of the discotic liquid crystalline compound and the plane of the polarizing film increases or decreases in the thickness direction of the optically anisotropic layer and with increasing distance from the plane of the polarizing film. is doing. The angle preferably decreases with increasing distance. Further, the change in angle can be continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and continuous decrease, or intermittent change including increase and decrease. The intermittent change includes a region where the tilt angle does not change in the middle of the thickness direction. Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.

  The average direction of the major axis of the discotic liquid crystalline compound on the polarizing film side can be generally adjusted by selecting the material of the discotic liquid crystalline compound or the alignment film, or by selecting the rubbing treatment method. . Further, the major axis (disk surface) direction of the discotic liquid crystalline compound on the surface side (air side) is generally adjusted by selecting the discotic liquid crystalline compound or the type of additive used together with the discotic liquid crystalline compound. be able to. Examples of the additive used together with the discotic liquid crystalline compound include the air interface alignment control agent (fluoro aliphatic group-containing polymer), the fluoropolymer and cellulose ester described later, a plasticizer, and a surfactant. And polymerizable monomers and polymers. The degree of change in the orientation direction of the major axis can be adjusted by selecting the liquid crystal compound and the additive as described above.

  The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

1-3. Fluoropolymer The optical compensation sheet of the present invention includes a fluoroaliphatic group-containing polymer (may be abbreviated as “fluorine polymer”) in addition to the above-described fluoroaliphatic group-containing polymer having a photoreactive group. It may be contained in the optically anisotropic layer. The fluoropolymer functions as an unevenness preventing agent for the optical compensation sheet. Therefore, by applying the optical compensation sheet to a large liquid crystal display device, it is possible to display an image with high display quality without causing unevenness.

As such a fluoropolymer, an acrylic resin or a methacrylic resin is preferable.
More preferably, the fluoropolymer used in the present invention is a polymer containing a repeating unit derived from a monomer represented by the following general formula (3), or a repeating unit derived from a monomer represented by the following general formula (3). And a polymer containing a repeating unit derived from a monomer represented by the following general formula (4), and a polymer obtained by copolymerizing a vinyl monomer copolymerizable with these monomers.

（一般式（３）中、Ｒ¹⁰は水素原子またはメチル基を表し、Ｘ¹⁰は酸素原子、イオウ原子または−Ｎ（Ｒ¹¹）−を表し、Ｈｆは水素原子またはフッ素原子を表し、ｒは１〜６の整数、ｓは２〜４の整数を表す。Ｒ¹¹は水素原子または炭素数１〜４のアルキル基を表す。） General formula (3)

(In General Formula (3), R ¹⁰ represents a hydrogen atom or a methyl group, X ¹⁰ represents an oxygen atom, a sulfur atom or —N (R ¹¹ ) —, Hf represents a hydrogen atom or a fluorine atom, and r represents an integer from 1 to 6, s is .R ¹¹ represents an integer of 2 to 4 represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

In the general formula (3), R ¹¹ is preferably a methyl group, an ethyl group, a propyl group or a butyl group, more preferably a hydrogen atom or a methyl group. X ¹⁰ is preferably an oxygen atom.
In general formula (3), r is preferably 1 or 2.
As for s in General formula (3), 2 or 3 is preferable.
Two or more monomers represented by the general formula (3) may be used.

（一般式（４）中、Ｒ²⁰は水素原子またはメチル基を表し、Ｙ²⁰は２価の連結基を表し、Ｒ²¹は置換基を有してもよいポリ（アルキレンオキシ）基または、置換基を有してもよい炭素数１〜２０の直鎖、分岐または環状のアルキル基を表す。） General formula (4)

(In the general formula (4), R ²⁰ represents a hydrogen atom or a methyl group, Y ²⁰ represents a divalent linking group, and R ²¹ represents a poly (alkyleneoxy) group which may have a substituent or a substituted group. Represents a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms which may have a group.)

In the general formula (4), the divalent linking group for Y ²⁰ is preferably an oxygen atom, a sulfur atom or N (R ²² ) —. Here, R ²² is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably a methyl group, an ethyl group, a propyl group, a butyl group, or the like. More preferred forms of R ²² are a hydrogen atom and a methyl group. Y ²⁰ is more preferably an oxygen atom, —N (H) — or N (CH ₃ ) —.
The poly (alkyleneoxy) group of R ²¹ can be represented by (R ²³ O) _x , where R ²³ is an alkylene group having 2 to 4 carbon atoms, such as —CH ₂ CH ₂ —, —CH ₂ CH _{2. CH 2 -, - CH (CH} 3) CH 2 -, or _{-CH (CH 3) CH (CH} 3) - is preferably.
The alkyleneoxy units in the poly (alkyleneoxy) group may be the same as in poly (propyleneoxy), or two or more different types of alkyleneoxy may be randomly distributed. It may be linear or branched propyleneoxy or ethyleneoxy units, or may be present as a linear or branched block of propyleneoxy units and a block of ethyleneoxy units.
In this poly (alkyleneoxy) chain, a plurality of poly (alkyleneoxy) units are linked to each other by one or more chain bonds (for example, -CONH-Ph-NHCO-, -S-, etc., where Ph represents a phenylene group) .) Can also be included. If the linkage in the chain has a valence of 3 or more, this provides a means for obtaining branched alkyleneoxy units. When this copolymer is used in the present invention, the molecular weight of the poly (alkyleneoxy) group is suitably from 250 to 3,000.

Examples of the linear, branched or cyclic alkyl group having 1 to 20 carbon atoms represented by R ²¹ include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, which may be linear and branched, Heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, octadecyl group, eicosanyl group, etc., and monocyclic cycloalkyl groups such as cyclohexyl group, cycloheptyl group and the like A polycyclic cycloalkyl group such as a bicycloheptyl group, a bicyclodecyl group, a tricycloundecyl group, a tetracyclododecyl group, an adamantyl group, a norbornyl group, or a tetracyclodecyl group is preferably used.

Examples of the substituent of the poly (alkyleneoxy) group or alkyl group represented by R ²¹ include a hydroxyl group, an alkylcarbonyl group, an arylcarbonyl group, an alkylcarbonyloxy group, a carboxyl group, an alkyl ether group, an aryl ether group, a fluorine atom, Examples include, but are not limited to, halogen atoms such as chlorine atom and bromine atom, nitro group, cyano group and amino group.

  The monomer represented by the general formula (4) is particularly preferably alkyl (meth) acrylate or poly (alkyleneoxy) (meth) acrylate.

  Specific examples of the fluoroaliphatic group-containing monomer represented by formula (3) or (4) and other fluoroaliphatic-containing monomers that can be used in the present invention are shown below, but the present invention is limited to these. It is not a thing.

Poly (alkyleneoxy) acrylate and methacrylate are commercially available hydroxypoly (alkyleneoxy) materials such as “Pluronic” (Pluronic (Asahi Denka Kogyo Co., Ltd.)), “Adeka Polyether” (Asahi Denka Kogyo ( “Carbowax” [Carbowax], “Triton” [Toriton (Rohm and Haas)) and “PEG” (Daiichi Kogyo Seiyaku Co., Ltd.) It can be produced by reacting a commercially available product with acrylic acid, methacrylic acid, acrylic chloride, methacrylic chloride or acrylic acid anhydride by a known method.
Separately, poly (oxyalkylene) diacrylate produced by a known method can also be used.

  The fluoropolymer of the present invention is preferably a homopolymer of the monomer represented by the general formula (3) or a copolymer of the monomer represented by the general formula (3) and a polyalkyleneoxy (meth) acrylate. It is particularly preferable to contain polyethyleneoxy (meth) acrylate or polypropyleneoxy (meth) acrylate.

  The copolymer of the monomer represented by the general formula (3) and the monomer represented by the general formula (4) used in the present invention is added with a monomer copolymerizable with these in addition to the above monomers. It may be a copolymer reacted in the above manner. A preferable copolymerization ratio of the copolymerizable monomer is 20 mol% or less, more preferably 10 mol% or less in all monomers. Such monomers include Polymer Handbook 2nd ed. , J .; Brandrup, Wiley interscience (1975) Chapter 2 Pages 1-483 can be used. For example, a compound having one addition polymerizable unsaturated bond selected from acrylic acid, methacrylic acid, acrylic esters, methacrylic esters, acrylamides, methacrylamides, allyl compounds, vinyl ethers, vinyl esters, etc. I can give you.

Specifically, the following monomers can be mentioned.
Acrylic esters:
Furfuryl acrylate, tetrahydrofurfuryl acrylate, etc. Methacrylates:
Furfuryl methacrylate, tetrahydrofurfuryl methacrylate, etc.

Allyl compounds:
Allyl esters (for example, allyl acetate, allyl caproate, allyl caprylate, allyl laurate, allyl palmitate, allyl stearate, allyl benzoate, allyl acetoacetate, allyl lactate, etc.), allyloxyethanol, etc.

Vinyl ethers:
Alkyl vinyl ethers (for example, hexyl vinyl ether, octyl vinyl ether, decyl vinyl ether, ethyl hexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, chloroethyl vinyl ether, 1-methyl-2,2-dimethylpropyl vinyl ether, 2-ethylbutyl vinyl ether, hydroxyethyl vinyl ether) , Diethylene glycol vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, butylaminoethyl vinyl ether, benzyl vinyl ether, tetrahydrofurfuryl vinyl ether, etc.)

Vinyl esters:
Vinyl bitylate, vinyl isobutyrate, vinyl trimethyl acetate, vinyl diethyl acetate, vinyl valerate, vinyl caproate, vinyl chloroacetate, vinyl dichloroacetate, vinyl methoxyacetate, vinyl butoxyacetate, vinyl lactate, vinyl-β-phenyl Butyrate, vinyl cyclohexyl carboxylate, etc.

Dialkyl itaconates:
Dialkyl or monoalkyl esters of fumaric acid such as dimethyl itaconate, diethyl itaconate, dibutyl itaconate, etc .:
Dibutyl fumarate, etc.Crotonic acid, itaconic acid, acrylonitrile, methacrylonitrile, maleilonitrile, styrene, etc.

The amount of the fluoroaliphatic group-containing monomer represented by the general formula (4) in the fluorine-based polymer used in the present invention is preferably 5 mol% or more, more preferably 20 mol% or more of the total monomer constituting the polymer. Yes, more preferably 30 mol% or more.
The amount of the monomer represented by the general formula (4) in the fluoropolymer of the present invention is preferably 5 mol% or more, more preferably 5 to 70 mol%, still more preferably, of the total amount of constituent monomers of the fluoropolymer. 5 to 60 mol%.

The mass average molecular weight of the fluoropolymer used in the present invention is preferably 3000 to 100,000, more preferably 6,000 to 80,000. The mass average molecular weight can be measured as a value converted to polystyrene (PS) using gel permeation chromatography (GPC).
Furthermore, the preferable content of the fluoropolymer according to the present invention with respect to the coating composition (a coating component excluding the solvent) mainly comprising a liquid crystalline compound is in the range of 0.005 to 8% by mass, more preferably 0. The range is 0.01 to 1% by mass, and more preferably 0.05 to 0.5% by mass. It is more effective when the addition amount of the fluorine-based polymer is 0.005% by mass or more, and when it is 8% by mass or less, the coating film is not sufficiently dried, or as an optical compensation sheet. It is possible to more effectively suppress adverse effects on performance (for example, uniformity of retardation).

  The fluorine-based polymer used in the present invention can be produced by a known and conventional method. For example, a general-purpose radical polymerization initiator is added and polymerized in an organic solvent containing monomers such as (meth) acrylate having a fluoroaliphatic group and (meth) acrylate having a polyalkyleneoxy group. Can be manufactured. Further, in some cases, other addition-polymerizable unsaturated compounds can be further added and produced by the same method as described above. Depending on the polymerizability of each monomer, a dropping polymerization method in which a monomer and an initiator are added dropwise to a reaction vessel is also effective for obtaining a polymer having a uniform composition.

  Hereinafter, although the example of the specific structure of the fluorine-type polymer used by this invention is shown, this invention is not limited to these. In addition, the number in a formula shows the mass percentage of each monomer component. Mw represents a mass average molecular weight.

1-5. Polymerization initiator The aligned liquid crystalline compound can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. 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 aromatics. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US patents) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970).
The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.
Light irradiation for the polymerization of the liquid crystalline compound is preferably performed using ultraviolet rays.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, more preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

1-6. Anti-repelling agent Generally, a polymer compound (polymer) can be suitably used as an anti-repelling agent for use with a discotic liquid crystalline compound to prevent repelling during coating. The polymer that can be used as the repellency inhibitor is not particularly limited as long as it is compatible with the liquid crystal compound and does not significantly inhibit the tilt angle change or orientation of the liquid crystal compound. Examples of the polymer that can be used as the repellency inhibitor are described in JP-A-8-95030, and particularly preferred specific polymer examples include cellulose esters. Examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose, and cellulose acetate butyrate. The addition amount of the polymer used for the purpose of preventing repellency is preferably in the range of 0.1 to 10% by mass with respect to the liquid crystal compound so as not to inhibit the alignment of the liquid crystal compound. More preferably in the range of mass%, still more preferably in the range of 0.1 to 5 mass%.

1-7. Other compositions that can be contained in the optically anisotropic layer In addition to the above composition, the optically anisotropic layer can be used in combination with a plasticizer, a surfactant, a polymerizable monomer, etc. In addition, the strength of the film, the orientation of the liquid crystal compound, and the like can be improved. These are preferably compatible with the liquid crystal compound and can change the tilt angle of the liquid crystal compound or 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] of JP-A No. 2002-296423. The amount of the compound added is preferably in the range of ˜50 mass%, more preferably in the range of 5 to 30 mass% with respect to the discotic liquid crystalline compound.

  Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] of JP-A No. 2001-330725.

2. Next, the support used for the optical compensation sheet of the present invention will be described in detail.
The support used for the optical compensation sheet of the present invention is preferably a transparent support made of glass or a transparent polymer film.
The transparent support preferably has a light transmittance of 80% or more. Examples of the polymer constituting the polymer film include cellulose esters (for example, monoacylate, diacylate and triacylate of cellulose), norbornene-based polymers and polymethyl methacrylate. A commercially available polymer (for Norbornene-based polymers, both Arton and Zeonex are trade names)) may be used. In addition, even a conventionally known polymer such as polycarbonate or polysulfone that easily develops birefringence can be improved in birefringence by modifying the molecule as described in International Publication WO 00/26705 pamphlet. If controlled, it can also be used in the optical compensation sheet of the present invention.

Among these, cellulose esters are preferable, and lower fatty acid esters of cellulose are more preferable. Lower fatty acid means a fatty acid having 6 or less carbon atoms. In particular, cellulose acylate having 2 to 4 carbon atoms is preferable. Cellulose acetate is particularly preferred. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may be used.
The viscosity average degree of polymerization (DP) of cellulose acetate is preferably 250 or more, and more preferably 290 or more. Cellulose acetate preferably has a narrow molecular weight distribution of Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight) by gel permeation chromatography. A specific value of Mw / Mn is preferably 1.0 to 1.7, and more preferably 1.0 to 1.65.

As the polymer film, it is preferable to use cellulose acetate having an acetylation degree of 55.0 to 62.5%. The acetylation degree is more preferably 57.0 to 62.0%.
The degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The degree of acetylation is determined by measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like).

In cellulose acetate, the hydroxyl groups at the 2-position, 3-position and 6-position of cellulose are not evenly substituted, but the substitution degree at the 6-position tends to be small. In the polymer film used in the present invention, it is preferable that the degree of substitution at the 6-position of cellulose is the same or greater than that at the 2- and 3-positions.
The ratio of the substitution degree at the 6-position to the total substitution degree at the 2-position, the 3-position, and the 6-position is preferably 30 to 40%, more preferably 31 to 40%, and more preferably 32 to 40%. Most preferably it is. The substitution degree at the 6-position is preferably 88% or more.
These specific acyl groups and the method for synthesizing cellulose acylate are described in detail on page 9 of the Japan Society for Invention and Innovation (Technical Number 2001-1745, published on March 15, 2001). .

When using a polymer film for an optical compensation sheet, the polymer film preferably has a desired retardation value. In this specification, Re and Rth respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ.
Re is measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) by making light of wavelength λ nm incident in the normal direction of the film. Rth was measured by making light having a wavelength λ nm incident from a direction inclined + 40 ° with respect to the normal direction of the film with the slow axis in the plane (determined by KOBRA 21ADH) as the tilt axis (rotation axis). A retardation value and a retardation value measured by making light having a wavelength λ nm incident from a direction inclined −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis). KOBRA 21ADH is calculated based on the retardation value measured in the direction. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical compensation sheets can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of the main optical compensation sheets are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49) Polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness.

  When two optically anisotropic layers are used in a liquid crystal display device, the retardation value (Rth) of the polymer film is preferably in the range of 70 to 250 nm. When one optically anisotropic layer is used for the liquid crystal display device, the retardation value (Rth) of the polymer film is preferably in the range of 150 to 400 nm.

  In addition, it is preferable that the birefringence ((DELTA) n: nx-ny) of a polymer film exists in the range of 0.00028-0.020. In particular, the birefringence {(nx + ny) / 2−nz} in the thickness direction of the cellulose acetate film is preferably in the range of 0.001 to 0.04.

  In order to adjust the retardation of the polymer film, a method of applying an external force such as stretching is common, but a retardation increasing agent for adjusting optical anisotropy may be added. For example, in order to adjust the retardation of a cellulose acylate film, it is preferable to use an aromatic compound having at least two aromatic rings as a retardation increasing agent. The aromatic compound is preferably used in the range of 0.01 to 20 parts by mass with respect to 100 parts by mass of cellulose acylate. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic hetero ring in addition to the aromatic hydrocarbon ring. For example, compounds described in European Patent 0911656A2, JP-A Nos. 2000-1111914, 2000-275434 and the like can be mentioned.

Furthermore, the hygroscopic expansion coefficient of the cellulose acetate film used for the optical compensation sheet of the present invention is preferably 30 × 10 ⁻⁵ /% relative humidity (RH) or less. The hygroscopic expansion coefficient is preferably 15 × 10 ⁻⁵ /% RH or less, and more preferably 10 × 10 ⁻⁵ /% RH or less. The hygroscopic expansion coefficient is preferably small, but usually it is 1.0 × 10 ⁻⁵ /% RH or more.
The hygroscopic expansion coefficient indicates the amount of change in the length of the sample when the relative humidity is changed at a constant temperature.
By adjusting the hygroscopic expansion coefficient, it is possible to prevent a frame-like transmittance increase (light leakage due to distortion) while maintaining the optical compensation function of the optical compensation sheet.
Hereinafter, a method for measuring the hygroscopic expansion coefficient will be described. A sample having a width of 5 mm and a length of 20 mm was cut out from the produced polymer film, and one end was fixed and suspended in an atmosphere of 25 ° C. and 20% RH (R ⁰ ). A weight of 0.5 g was hung from the other end and left for 10 minutes, and the length (L ⁰ ) was measured. Next, with the temperature kept at 25 ° C., the humidity was set to 80% RH (R ¹ ), and the length (L ¹ ) was measured. The hygroscopic expansion coefficient was calculated by the following equation. The measurement was performed 10 samples for the same sample, and the average value was adopted.
Hygroscopic expansion coefficient [/% RH] = {(L ¹ −L ⁰ ) / L ⁰ } / (R ¹ −R ⁰ )

  In order to reduce the dimensional change due to moisture absorption of the polymer film, it is preferable to add a compound having a hydrophobic group or fine particles. As the compound having a hydrophobic group, a material corresponding to a plasticizer or a degradation inhibitor having a hydrophobic group such as an aliphatic group or an aromatic group in the molecule is particularly preferably used. It is preferable that the addition amount of these compounds exists in the range of 0.01-10 mass% with respect to the solution (dope) to adjust. In addition, the free volume in the polymer film may be reduced. Specifically, the smaller the amount of residual solvent during film formation by the solvent casting method described later, the smaller the free deposition. It is preferable to dry under the condition that the residual solvent amount with respect to the cellulose acetate film is in the range of 0.01 to 1.00% by mass.

  Additives described above to be added to the polymer film or additives that can be added in accordance with various purposes (for example, UV inhibitors, release agents, antistatic agents, deterioration inhibitors (for example, antioxidants, peroxide decomposers, The radical inhibitor, metal deactivator, acid scavenger, amine), infrared absorber and the like may be solid or oily. Moreover, when a film is formed from a multilayer, the kind and addition amount of the additive of each layer may differ. For these details, the materials described in detail on pages 16 to 22 of the Japan Society of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, Invention Association of March 15, 2001) are preferably used. The amount of these additives to be used is not particularly limited as long as the amount of each material exhibits its function, but it is preferably used in the range of 0.001 to 25% by mass in the entire polymer film composition.

[Production method of polymer film]
The polymer film is preferably produced by a solvent cast method. In the solvent cast method, a film is produced using a solution (dope) in which a polymer material is dissolved in an organic solvent.
The dope is cast on a drum or band and the solvent is evaporated to form a film. The concentration of the dope before casting is preferably adjusted so that the solid content is 18 to 35%. The surface of the drum or band is preferably finished in a mirror state.
The dope is preferably cast on a drum or band having a surface temperature of 10 ° C. or less. After casting, it is preferable to dry it by applying air for 2 seconds or more. The obtained film can be peeled off from the drum or band and further dried with high-temperature air whose temperature is successively changed from 100 to 160 ° C. to evaporate the residual solvent. The above method is described in Japanese Patent Publication No. 5-17844. According to this method, it is possible to shorten the time from casting to stripping. In order to carry out this method, it is necessary for the dope to gel at the surface temperature of the drum or band during casting.

In the casting step, one type of cellulose acylate solution may be cast as a single layer, or two or more types of cellulose acylate solutions may be cast simultaneously and / or sequentially.
As a method of co-casting a plurality of cellulose acylate solutions of two or more layers as described above, for example, a solution containing cellulose acylate from a plurality of casting openings provided at intervals in the traveling direction of the support. A method of casting and laminating each (for example, a method described in JP-A-11-198285), a method of casting a cellulose acylate solution from two casting ports (described in JP-A-6-134933) Method), a method of wrapping a flow of a high-viscosity cellulose acylate solution with a low-viscosity cellulose acylate solution and simultaneously extruding the high-viscosity and low-viscosity cellulose acylate solutions (described in JP-A-56-162617) Method). The present invention is not limited to these.
The manufacturing process of these solvent casting methods is described in detail on pages 22 to 30 of the Japan Society of Invention and Innovation Technical Bulletin (Public Technical Number 2001-1745, Invention Association of March 15, 2001). (Including co-casting), metal support, drying, peeling, stretching and the like.

  The thickness of the support of the present invention is preferably 15 to 120 μm, more preferably 30 to 80 μm.

[Surface treatment of support]
The support (polymer film) is preferably subjected to a surface treatment. Surface treatment includes corona discharge treatment, glow discharge treatment, flame treatment, acid treatment, alkali treatment and ultraviolet irradiation treatment. Details of these are described in detail on pages 30 to 32 of the Japan Society for Invention and Innovation Technical Report (Technical Number 2001-1745, Invention Association issued on March 15, 2001). Of these, alkali saponification treatment is particularly preferred, and is particularly effective as a surface treatment for cellulose acylate films.
The alkali saponification treatment may be performed by immersing in a saponification solution or applying a saponification solution. Examples of the coating method include a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method. Examples of the alkali saponification solution include potassium hydroxide solution and sodium hydroxide solution, and the prescribed concentration of hydroxide ions is preferably in the range of 0.1 to 3.0 mol / l. Further, the alkaline treatment liquid contains a solvent having good wettability to the support (eg, isopropyl alcohol, n-butanol, methanol, ethanol, etc.), a surfactant, a wetting agent (eg, diols, glycerin, etc.). As a result, the wettability of the saponification solution to the support, the stability of the saponification solution over time, and the like are improved. Specifically, description of the content is mentioned, for example in Unexamined-Japanese-Patent No. 2002-82226 and international publication WO02 / 46809 pamphlet.

  As a means to be performed in addition to the surface treatment method described above, or a means to be used instead, an undercoat layer (described in JP-A-7-333433) or a resin layer such as gelatin containing both a hydrophobic group and a hydrophilic group A single layer method in which only one layer is applied, a layer (hereinafter abbreviated as the undercoat first layer) is provided as a first layer, which adheres well to a polymer film, and a gelatin, etc., which adheres well to an alignment film as a second layer thereon There is a so-called multi-layer method (for example, a method described in JP-A No. 11-248940) in which a hydrophilic resin layer (hereinafter referred to as an undercoat second layer) is applied.

3. Alignment film The optical compensation sheet of the present invention is preferably provided with an alignment film between the support surface-treated as described above and the optically anisotropic layer provided thereon. The alignment film has a function of defining the alignment direction of the liquid crystalline compound.

  The alignment film is an organic compound (for example, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film that generates an alignment function by light irradiation can also be used. For example, a methacrylate polymer described in JP-A-10-278123 can be applied to the present invention.

In the present invention, it is preferable to impart alignment ability to the alignment film by rubbing treatment or light irradiation, and it is more preferable to impart alignment ability to the alignment film by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning the liquid crystal compound.
In the present invention, in addition to the function of aligning the liquid crystalline compound, the crosslinking having the function of binding a side chain having a crosslinkable functional group (for example, a double bond) to the main chain or aligning the liquid crystalline compound. It is preferable to introduce a functional functional group into the side chain.
As the polymer used in the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can also be used.

  Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohols and modified polyvinyl alcohols, poly (N-methylol acrylamide) described in paragraph No. [0022] of JP-A-8-338913, for example. , Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (for example, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferable, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol are more preferable, and polyvinyl alcohol and modified polyvinyl alcohol are more preferable. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization.

  The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

The side chain having the function of aligning the liquid crystal compound generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal compound and the required alignment state.
For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Examples include substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy groups, dialkoxy groups, monoalkoxy groups), and the like. Specific examples of these modified polyvinyl alcohol compounds include those described in, for example, paragraph numbers [0022] to [0145] of JP-A No. 2000-155216 and paragraph numbers [0018] to [0022] of JP-A No. 2002-62426. Etc.

When the side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer or the crosslinkable functional group is introduced into the side chain having the function of aligning the liquid crystal compound, the alignment film polymer and the optically anisotropic film The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, by introducing a crosslinkable functional group into the alignment film polymer, the strength of the optical compensation sheet becomes more remarkable.
The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] of JP-A No. 2000-155216.

  Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent. Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [0024] of JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high-temperature and high-humidity atmosphere for a long time, sufficient durability without generation of reticulation can be obtained.

  The alignment film is preferably formed by applying an alignment film composition containing the polymer and a crosslinking agent, which are alignment film forming materials, onto a support, followed by heat drying (crosslinking) and rubbing treatment. As described above, the crosslinking reaction can be carried out at any time after coating on the support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (for example, 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 alignment film and also an optically anisotropic layer can be suppressed more effectively.

  The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heat drying can be preferably performed at 20 to 110 ° C. In order to form sufficient crosslinking, 60 ° C to 100 ° C is more preferable. The drying time is preferably 1 minute to 36 hours, and more preferably 1 minute to 30 minutes. The pH is also preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, pH 4.5 to 5.5 is preferable, and 5 is particularly preferable.

  The alignment film is preferably provided on the support or the undercoat layer. The alignment film is preferably obtained by rubbing the surface after crosslinking the polymer layer as described above.

  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. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.

Next, the alignment film is functioned to align the 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.

4). Coating of optically anisotropic layer on support The optically anisotropic layer is formed by applying a coating liquid containing a liquid crystalline compound, a fluoroaliphatic group-containing polymer, and other optional components on the alignment film, and then desired. The alignment state (preferably hybrid alignment) is used.

As the solvent used for preparing the coating liquid for the optically anisotropic layer, 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, tetrachloroethane), 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 (for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, or a die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and still more preferably 1 to 10 μm.

  In the present invention, the liquid crystalline compound is aligned at the tilt angle of the alignment film at the interface with the alignment film, and is aligned at the tilt angle of the air interface at the interface with air. Although it is not the actual situation by uniformly aligning the liquid crystal compound (monodomain alignment), when expressed in an image, the tilt of the liquid crystal compound is directed from the air interface to the alignment film interface, that is, in the thickness direction of the optically anisotropic layer. Hybrid orientation with continuously changing corners can be realized. An optical compensation sheet having an optically anisotropic layer formed by hybrid alignment of the liquid crystalline compound and fixing to the alignment state contributes to an increase in the viewing angle of the liquid crystal display device, and contrast to a change in viewing angle. This contributes to preventing reduction, gradation or black-and-white reversal, and hue change.

Here, the “tilt angle” refers to the normal between the major axis direction of the liquid crystal compound molecule (for example, the normal of the disc surface of the discotic liquid crystal compound) and the interface (alignment film interface or air interface). In the present invention, the tilt angle on the alignment film side is preferably 3 ° to 30 °, and the tilt angle on the air interface side is preferably 40 to 80 °. The tilt angle on the alignment film side is further preferably 5 ° to 50 °, more preferably from the viewpoint of achieving both the shortening of the monodomain formation time and the preferable optical performance as the optical compensation sheet. Is 10 to 50 °, particularly preferably 10 to 30 °. By setting the tilt angle on the alignment film side to 3 ° or more, the time required for monodomain alignment of the liquid crystal compound, particularly the discotic liquid crystal compound, can be shortened, and the tilt angle on the alignment film side is set to 80 ° or less. As a result, more preferable optical performance can be obtained as an optical compensation sheet. Moreover, the preferable tilt angle on the air interface side is 40 to 80 °, more preferably 50 to 80 °, and particularly preferably 60 to 80 °. In particular, the tilt angle θ ¹ of the discotic liquid crystalline compound at the interface of the alignment layer of the optically anisotropic layer preferably satisfies 10 ° ≦ θ ¹ ≦ 30 °.

  If the liquid crystalline compound is aligned and the state thereof is fixed by polymerization or the like, the alignment state can be maintained without an alignment film. Therefore, after the optically anisotropic layer is formed on an alignment film (for example, an alignment film formed on a temporary support), only the optically anisotropic layer is transferred onto another support, thereby the present invention. It is also possible to produce an optical compensation sheet. That is, the optical compensation sheet produced by the production method of the present invention includes an optical compensation sheet that does not include an alignment film.

<Application of optical compensation sheet>
The optical compensation sheet of the present invention can be used for a polarizing plate (elliptical polarizing plate) in combination with a polarizing film. Furthermore, by applying to a transmissive liquid crystal display device in combination with a polarizing film, it contributes to an increase in viewing angle. The elliptically polarizing plate and liquid crystal display device using the optical compensation sheet of the present invention will be described below.

[Elliptically polarizing plate]
The elliptically polarizing plate can be produced by laminating the optical compensation sheet of the present invention and a polarizing film. By using the optical compensation sheet of the present invention, an elliptically polarizing plate capable of expanding the viewing angle of the liquid crystal display device can be provided. Examples of the polarizing film include an iodine polarizing film, a dye polarizing film using a dichroic dye, and a polyene polarizing film. The iodine-based polarizing film and the dye-based polarizing film can be generally produced using a polyvinyl alcohol film. The polarization axis of the polarizing film corresponds to a direction perpendicular to the stretching direction of the film.

  The polarizing film is laminated on the optically anisotropic layer side of the optical compensation sheet. It is preferable to form a protective film on the surface of the polarizing film opposite to the side on which the optical compensation sheet is laminated. The protective film is preferably a protective film (transparent protective film) having a light transmittance of 80% or more. As the transparent protective film, a cellulose ester film is preferably used, more preferably a triacetyl cellulose film. The cellulose ester film is preferably formed by a solvent cast method. The thickness of the protective film is preferably 20 to 500 μm, and more preferably 50 to 200 μm.

[Liquid Crystal Display]
By using the optical compensation sheet of the present invention, it is possible to provide a liquid crystal display device having a wide viewing angle. In addition, a liquid crystal display device that can display a high-quality image without display unevenness can be provided. An optical compensation sheet for a liquid crystal cell in a TN (Twisted Nematic) mode is disclosed in JP-A-6-214116, U.S. Pat. Nos. 5,583,679 and 5,646,703, and German Patent Publication 3911620A1. There is description in the gazette. An optical compensation sheet for a liquid crystal cell in an IPS (In-Plane Switching) mode or a FLC (Ferroelectric Liquid Crystal) mode is described in JP-A-10-54982. Furthermore, optical compensation sheets for liquid crystal cells in OCB (Optically Compensatory Bend) mode or HAN (Hybrid Aligned Nematic) mode are described in US Pat. No. 5,805,253 and WO 96/37804. Furthermore, an optical compensation sheet for liquid crystal cells in STN (Super Twisted Nematic) mode is described in JP-A-9-26572. An optical compensation sheet for liquid crystal cells in a VA (Vertically Aligned) mode is described in Japanese Patent No. 2866372.

  In the present invention, optical compensation sheets for liquid crystal cells of various modes can be produced with reference to the above publication. The optical compensation sheet of the present invention can be applied to a liquid crystal display device in combination with a liquid crystal cell driven in the various modes described above. The optical compensation sheet of the present invention is particularly effective in a TN mode or OCB mode liquid crystal display device.

  The present invention will be described more specifically with reference to the following 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. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[Example 1]
(Production of polymer substrate)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.

Cellulose acetate solution composition:
Cellulose acetate (linter) with an acetylation degree of 60.9% 80 parts by mass Cellulose acetate (linter) with an acetylation degree of 60.8% 20 parts by mass Triphenyl phosphate (plasticizer) 7.8 parts by mass Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by mass Methylene chloride (first solvent) 300 parts by mass Methanol (second solvent) 54 parts by mass 1-butanol (third solvent) 11 parts by mass

Into the 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 and stirred while heating to prepare a retardation increasing agent solution.
A dope was prepared by mixing 474 parts by mass of the cellulose acetate solution with 25 parts by mass of the retardation increasing agent solution and stirring sufficiently. The addition amount of the retardation increasing agent was 3.5 parts by mass with respect to 100 parts by mass of cellulose acetate.

Retardation raising agent

The obtained dope was cast using a band casting machine. After the film surface temperature on the band reached 40 ° C., it was dried for 1 minute, peeled off, and then the polymer base material (PK-1) having a residual solvent amount of 0.3 mass% with 140 ° C. drying air Manufactured.
The obtained polymer substrate (PK-1) had a width of 1500 mm and a thickness of 65 μm. When the retardation value (Re) at a wavelength of 632.8 nm was measured using KOBRA-21ADH (manufactured by Oji Scientific Instruments), it was 4 nm. Moreover, it was 78 nm when the retardation value (Rth) in wavelength 632.8nm was measured.

(Surface treatment of polymer substrate and formation of alignment film)
The polymer substrate (PK-1) was immersed in a 2.0 mol / l potassium hydroxide solution (25 ° C.) for 2 minutes, neutralized with 2.0 mol / l sulfuric acid, washed with pure water and dried. The surface energy was determined by a contact angle method and found to be 63 mN / m. On this polymer substrate (PK-1), an alignment film coating solution having the following composition was coated at a coating amount of 28 ml / m ² with a # 16 wire bar coater. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 90 ° C. for 150 seconds.

Alignment film composition:
The following modified polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Glutaraldehyde (crosslinking agent) 0.5 parts by weight

Modified polyvinyl alcohol

  Next, the alignment film was rubbed in a direction parallel to the slow axis (measured at a wavelength of 632.8 nm) of the polymer substrate (PK-1).

(Formation of optically anisotropic layer)
On the alignment film,
The following discotic liquid crystalline compound 41.01 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 4.06 parts by mass Illustrative compound of fluoroaliphatic group-containing polymer: P- 10 0.16 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 1.35 parts by mass sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.45 parts by mass of 102 parts by mass It melt | dissolved in methyl ethyl ketone and it was set as the liquid crystalline composition (coating liquid), and this was apply | coated with the wire bar of # 3.4. This is heated and matured for 30 seconds in a constant temperature zone of 120 ° C., and further, using a 200 mW / cm high-pressure mercury lamp, non-polarized ultraviolet rays are irradiated from the 45 ° direction (single direction) to the support surface to produce a discotic. The liquid crystal compound was aligned. The irradiation dose at this time was 3 J / cm ² . Then, it stood to cool to room temperature. Thus, an optically anisotropic layer was formed, and an optical compensation sheet (KH-60) was produced.

Discotic liquid crystalline compounds

(Preparation of polarizing plate)
Using a polyvinyl alcohol-based adhesive, KH-60 (optical compensation sheet) was attached to one side of the polarizing film (HF-1). Further, a saponification treatment was performed on a 80 μm thick triacetyl cellulose film (TD80U: manufactured by Fuji Photo Film Co., Ltd.), and the film was attached to the opposite side of the polarizing film using a polyvinyl alcohol-based adhesive.
The transmission axis of the polarizing film and the slow axis of PK-1 were arranged in parallel. The transmission axis of the polarizing film and the slow axis of the triacetyl cellulose film were arranged so as to be orthogonal to each other. In this way, a polarizing plate (HB-1) was produced.

[Examples 2 to 4]
Production of the support and formation / rubbing of the alignment film were carried out in the same manner as in Example 1.
In the preparation of the liquid crystal composition, the fluoroaliphatic group-containing polymer was changed as shown in Table 1.
[Comparative Example 1]
An optical compensation sheet was produced in the same manner as in Example 1 except that the fluoroaliphatic group-containing polymer was not added in the preparation of the liquid crystalline composition.
[Comparative Example 2]
An optical compensation sheet was prepared in the same manner as in Comparative Example 1 except that the alignment aging time was changed from 30 seconds to 3 minutes in the aging of the liquid crystalline composition.

(Evaluation with TN liquid crystal cell)
A pair of polarizing plates provided in a liquid crystal display device (AQUAS LC20C1S, manufactured by Sharp Corporation) using a TN type liquid crystal cell is peeled off, and the polarizing plate (HB-1) prepared in Example 1 is optically replaced. The compensation sheets (KH-80-1) were attached to the observer side and the backlight side one by one through an adhesive so that the compensation sheet (KH-80-1) was on the liquid crystal cell side. The transmission axis of the polarizing plate on the viewer side and the transmission axis of the polarizing plate on the backlight side were arranged to be in the O mode.
About the produced liquid crystal display device, the viewing angle was measured in eight steps from black display (L1) to white display (L8) using the measuring machine (EZ-Contrast160D, ELDIM company make).
The viewing angles were similarly measured for Examples 2 to 4 and Comparative Example 1. The measurement results are shown in Table 1.

(Tilt angle evaluation of liquid crystalline compounds)
In an optically anisotropic layer in which a discotic compound or rod-like compound is oriented, it is difficult to directly and accurately measure the tilt angles θ ¹ and θ ² of the optically anisotropic layer. Therefore, in this specification, θ ¹ and θ ² are calculated by the following method. Although this method does not accurately represent the actual orientation state of the present invention, it is effective as a means for expressing the relative relationship between some optical characteristics of the optical compensation sheet.
In this method, in order to facilitate calculation, the following two points are assumed and the tilt angle at the two interfaces of the optically anisotropic layer is used.
1. The optically anisotropic layer is assumed to be a multilayer body composed of layers containing a discotic liquid crystalline compound or a rod-like liquid crystalline compound. Further, it is assumed that the minimum unit layer (the tilt angle of the discotic liquid crystal compound or the rod-like liquid crystal compound is uniform in the layer) constituting it is optically uniaxial.
2. It is assumed that the tilt angle of each layer changes monotonically with a linear function along the thickness direction of the optically anisotropic layer.
The specific calculation method is as follows.
(1) In a plane in which the tilt angle of each layer changes monotonically with a linear function along the thickness direction of the optically anisotropic layer, the incident angle of the measurement light to the optically anisotropic layer is changed, and three or more The retardation value is measured at the measurement angle. In order to simplify measurement and calculation, it is preferable to measure the retardation value at three measurement angles of −40 °, 0 °, and + 40 °, with the normal direction to the optically anisotropic layer being 0 °. Such measurements include KOBRA-21ADH and KOBRA-WR (manufactured by Oji Scientific Instruments), transmission ellipsometer AEP-100 (manufactured by Shimadzu Corporation), M150 and M520 (manufactured by JASCO Corporation) ), ABR10A (manufactured by UNIOPT Co., Ltd.).
(2) In the above model, the refractive index of ordinary light in each layer is no, the refractive index of extraordinary light is ne (ne is the same in all layers, and no is the same), and the thickness of the entire multilayer body is d And Further, based on the assumption that the tilt direction of each layer and the uniaxial optical axis direction of the layer coincide with each other, the calculation of the angular dependence of the retardation value of the optically anisotropic layer agrees with the measured value. Fitting is performed using the tilt angle θ ^{1 on one} surface of the isotropic layer and the tilt angle θ ² on the other surface as variables, and θ ¹ and θ ² are calculated.
Here, for no and ne, known values such as literature values and catalog values can be used. If the value is unknown, it can also be measured using an Abbe refractometer. The thickness of the optically anisotropic layer can be measured by an optical interference film thickness meter, a cross-sectional photograph of a scanning electron microscope, or the like.
Based on the above method, the tilt angle near the alignment film of the liquid crystalline compound and the tilt angle near the air interface in the optically anisotropic layer of each optical compensation sheet were measured. The measurement wavelength is 632.8 nm, and the results are shown in Table 1.

As can be seen from the results of Comparative Example 1 shown in Table 1 above, the optically anisotropic layer containing no fluoroaliphatic group-containing polymer of the present invention does not lose schlieren defects when the aging time is short, and the optical compensation sheet It was not preferable as. Further, from the results of Comparative Example 2 and Examples 1 to 4, by using the fluoroaliphatic group-containing polymer of the present invention, the schlieren defect does not disappear with the conventional technology, and the liquid crystalline compound can be obtained without schlieren defect in a short aging time. It was possible to align it, and it became more excellent in improving the production efficiency.
In the optical compensation sheet containing the exemplary compound of the present invention in the optically anisotropic layer, the tilt angle at the air interface of the liquid crystalline compound is controlled to an optimum value, and thus the viewing angle expansion effect is excellent.

Claims (8)

An optical compensation sheet having an optically anisotropic layer on a support, wherein the optically anisotropic layer contains at least one liquid crystal compound and a fluoroaliphatic group-containing polymer having a photoreactive group, The optical compensation sheet obtained by irradiating the anisotropic layer with light. The fluoroaliphatic group-containing polymer having a photoreactive group is a repeating unit derived from at least one monomer represented by the following general formula (1), and at least one monomer represented by the following general formula (2) The optical compensation sheet according to claim 1, wherein the optical compensation sheet is a copolymer containing a repeating unit derived from
General formula (1)

(In General Formula (1), R ¹ represents a hydrogen atom or a substituent, L ¹ represents a single bond or a divalent linking group, A represents a photoreactive group, and Y ¹ represents —NR ^a. — (R ^a represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom) or —O—.
General formula (2)

(In General Formula (2), R ² represents a hydrogen atom or a substituent, L ² represents a single bond or a divalent linking group, and Rf represents an alkyl group partially or entirely substituted with a fluorine atom. Y ² represents —NR ^a — (R ^a represents an alkyl group having 1 to 5 carbon atoms or a hydrogen atom) or —O—. The optical compensation sheet according to claim 1, wherein the light irradiation is light irradiation from a single direction. The optical compensation sheet has an alignment film, and the alignment function of the alignment film is imparted by rubbing, non-polarized light irradiation from a single direction, or polarized light irradiation from a single direction. 4. The optical compensation sheet according to any one of 3 above. The optical compensation sheet according to claim 1, wherein the at least one liquid crystalline compound is a discotic liquid crystalline compound. The optical compensation sheet according to claim 1, wherein the discotic liquid crystalline compound is fixed in a hybrid orientation. A liquid crystal display device comprising the optical compensation sheet according to claim 1. A method for producing an optical compensation sheet having an alignment film and an optically anisotropic layer on a support, wherein the optically anisotropic layer contains at least one liquid crystal compound and a fluoroaliphatic group having a photoreactive group A method for producing an optical compensation sheet, comprising a polymer, wherein the optically anisotropic layer is irradiated with light.