JP2012208397A - Optical film, polarizer, liquid crystal display and homeotropic surfactant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical film that includes an optical anisotropic layer excellent in adhesiveness between the optical anisotropic layer and an alignment film.SOLUTION: An optical film comprises a base 1, a rubbed alignment film 2 and an optical anisotropic layer 3 including a liquid crystal compound, in this order. The optical anisotropic layer includes at least one type of onium compound represented by general formula (I). In the general formula (I), a ring A represents a quaternary ammonium ion of nitrogen-containing heterocyclic ring, X represents an anion, Lrepresents a divalent linking group, Lrepresents a singly-bonded or divalent linking group, Yrepresents a divalent linking group including a five- or six-membered ring as a partial structure, Z represents a divalent linking group including an alkylene group of Cto Cas a partial structure, and Pand Pindividually and independently represent a monovalent substituent including a polymerizable unsaturated ethylene group.

Description

  The present invention relates to an optical film useful for optical compensation of a liquid crystal display device, a vertical alignment agent, a polarizing plate having the same, and a liquid crystal display device.

  Conventionally, it has been proposed to use an optically anisotropic layer formed by fixing the hybrid alignment state of liquid crystal molecules for optical compensation of a TN mode liquid crystal display device. In particular, in recent years, various discotic liquid crystal compounds having high Δn and low wavelength dispersion have been developed, and use of these compounds in optical compensation members is expected (for example, Patent Documents 1 and 2).

  Here, “hybrid alignment of discotic liquid crystal molecules” means that the angle (hereinafter referred to as “tilt angle”) between the disc surface and the layer surface of the discotic liquid crystal molecules changes (increases or decreases) in the layer thickness direction. Orientation state. Since the optically anisotropic layer is generally formed by orienting a composition containing a discotic liquid crystal compound on the surface of the alignment film, the layer has an alignment film interface and an air interface. To do. In hybrid alignment, the tilt angle is large on the alignment film interface side and small on the air interface side (that is, the tilt angle is decreased from the alignment film interface toward the air interface, hereinafter, “ `` Reverse hybrid orientation ''), and the aspect in which the tilt angle is small on the alignment film interface side and large on the air interface side (that is, the tilt angle increases from the alignment film interface toward the air interface, There are two modes (hereinafter referred to as “positive hybrid orientation”). Conventionally, as the optical compensation film using discotic liquid crystal molecules, the latter mode, that is, the positive hybrid alignment is generally used.

  Various optical films having an optically anisotropic layer in which the reverse hybrid orientation of a liquid crystal compound is fixed have been proposed (for example, Patent Documents 3 and 4). By the way, for example, when the discotic liquid crystal compound molecules are aligned perpendicularly to the alignment film surface (hereinafter referred to as “vertical alignment”) on the rubbing-treated surface of the alignment film, the discotic liquid crystal molecules In general, the vertical orientation is performed with the disk surface fitted in the groove formed by rubbing. Therefore, in the reverse hybrid alignment state realized in the past, most of the discotic liquid crystal molecules vertically aligned at the alignment film interface are vertically aligned with the disk surface parallel to the rubbing direction. In such an optically anisotropic layer in which the conventional reverse hybrid orientation is fixed, the discotic liquid crystal molecules are oriented with the disc surface parallel to the rubbing direction at the orientation film surface interface, and the slow axis is It appears in a direction parallel to the rubbing direction. On the other hand, in continuous production, rubbing is generally performed along the conveying direction of a long film. Therefore, when the optically anisotropic layer in which the reverse hybrid orientation is fixed is continuously produced in the form of a long film, the slow axis is parallel to the longitudinal direction. However, even if an optically anisotropic layer having such characteristics is continuously produced in a long shape, it cannot be bonded with the long polarizer so that the longitudinal direction coincides. It has become a negative effect of practical use.

  As a method for increasing the tilt angle on the alignment film interface side including the discotic liquid crystal compound and the rod-shaped liquid crystal compound, that is, for vertically aligning the liquid crystal compound, for example, an alignment controller is included in the optically anisotropic layer. It has been proposed (for example, Patent Documents 4 and 5).

JP 2006-76992 A JP 2006-2220 A JP 2002-122736 A Japanese Patent No. 4512468 JP 2006-106662 A

  As described above, conventionally, as an optical compensation film using liquid crystal molecules, an optical compensation film having an optically anisotropic layer formed by fixing positive hybrid alignment is generally used. As a result of intensive studies by the present inventors, the alignment of liquid crystal molecules in the positive hybrid alignment state is slightly disturbed at the micro level, and this micro level of alignment disorder is caused by the micro-alignment axis deviation of the optical anisotropic layer. It has been found that, when used in a liquid crystal display device as an optical compensation member, it becomes a cause of lowering the front contrast (CR). In particular, in recent years, the increase in front contrast has been remarkable, and it has been demanded to solve the cause of the decrease in front CR, which has not been regarded as a problem in the past. On the other hand, in the aspect using the conventional reverse hybrid orientation, as described above, there are manufacturing problems.

In order to form reverse hybrid alignment, it is necessary to vertically align liquid crystal molecules at the alignment film interface. In order to stably vertically align the liquid crystal molecules at the alignment film interface, it is effective to use an alignment control agent exhibiting high uneven distribution at the alignment film side interface. However, when an alignment control agent having such characteristics is used, there is a problem that the adhesion at the interface between the optically anisotropic layer and the alignment film is lowered.
The present invention has been made in view of the above problems, and an optical film in which liquid crystal molecules are in a stable vertical alignment state at the alignment film interface and has excellent adhesion between the alignment film and the optically anisotropic layer. Another object of the present invention is to provide a vertical alignment agent that can be used in the production thereof, and a polarizing plate and a liquid crystal display device having the same.

一般式（Ｉ）中、環Ａは含窒素複素環の第４級アンモニウムイオンを表し；Ｘはアニオンを表し；Ｌ¹は二価の連結基を表し；Ｌ²は単結合又は二価の連結基を表し；Ｙ¹は５又は６員環を部分構造として有する２価の連結基を表し；ＺはＣ₂〜₂₀のアルキレン基を部分構造として有する２価の連結基を表し；Ｐ¹及びＰ²はそれぞれ独立に重合性エチレン性不飽和基を有する一価の置換基を表す。
［２］ 前記少なくとも１種の一般式（Ｉ）で表されるオニウム化合物が、下記一般式（Ｉ−１）又は（Ｉ−２）で表される化合物である［１］の光学フィルム：

一般式（Ｉ−１）及び（Ｉ−２）の各記号の定義は、一般式（Ｉ）中のそれぞれと同義であり；Ｌ³及びＬ⁴はそれぞれ独立に二価の連結基を表し；Ｙ²及びＹ³はそれぞれ独立に置換基を有していてもよい６員環であり；ｍは１又は２を表し、ｍが２の場合、二つのＬ⁴および二つのＹ³は、互いに同一でも異なっていてもよく；ｐは１〜１０の整数を表す。
［３］ 前記少なくとも１種の一般式（Ｉ）で表されるオニウム化合物が、下記一般式（Ｉ−３）又は（Ｉ−４）で表される化合物の少なくともいずれかである［２］の光学フィルム：

一般式（Ｉ−３）及び（Ｉ−４）の各記号の定義は、一般式（Ｉ−１）及び（Ｉ−２）中のそれぞれと同義であり；Ｒ’は、置換基を表し；ｂは１〜４の整数を表す。
［４］ 前記配向膜が、変性又は未変性ポリビニルアルコールを主成分として含有する膜である［１］〜［３］のいずれかの光学フィルム。
［５］ 前記光学異方性層が、さらに、少なくとも１種のフルオロ脂肪族基を有する繰り返し単位を含む共重合体を含有する［１］〜［４］のいずれかの光学フィルム。
［６］ 前記液晶化合物の分子の配向膜側チルト角が、空気界面側チルト角より大きい配向状態に固定される［１］〜［５］のいずれかの光学フィルム。
［７］ 前記光学異方性層の遅相軸方向が、前記配向膜のラビング方向と直交する［１］〜［６］のいずれかの光学フィルム。
［８］ 前記液晶化合物が、ディスコティック液晶化合物である［１］〜［７］のいずれかの光学フィルム。
［９］ 前記ディスコティック液晶化合物が、下記式（Ｘ）を円盤状コアとして有するディスコティック液晶化合物である［８］の光学フィルム：

式（Ｘ）中、Ｒはそれぞれ式（Ｘ）の化合物が液晶性を示すために必要な有機置換基を表す。
［１０］ 前記オニウム化合物の添加量が、前記液晶化合物１００質量部に対し、０．５〜３質量部である［１］〜［９］のいずれかの光学フィルム。
［１１］ 前記フルオロ脂肪族基を有する繰り返し単位を含む共重合体の添加量が、前記液晶化合物１００質量部に対し、０．２〜２．０質量部である［５］〜［１０］のいずれかの光学フィルム。
［１２］ 偏光膜と、［１］〜［１１］のいずれかの光学フィルムと、を少なくとも有する偏光板。
［１３］ ［１２］の偏光板を少なくとも有する液晶表示装置。
［１４］ ＴＮモードである［１３］の液晶表示装置。
［１５］ 下記一般式（Ｉ）で表されるオニウム化合物を含むことを特徴とする垂直配向剤：

一般式（Ｉ）中、環Ａは含窒素複素環の第４級アンモニウムイオンを表し；Ｘはアニオンを表し；Ｌ¹は二価の連結基を表し；Ｌ²は単結合又は二価の連結基を表し；Ｙ¹は５又は６員環を部分構造として有する２価の連結基を表し；ＺはＣ₂〜₂₀のアルキレン基を部分構造として有する２価の連結基を表し；Ｐ¹及びＰ²はそれぞれ独立に重合性エチレン性不飽和基を有する一価の置換基を表す。 Means for solving the above problems are as follows.
[1] An optical film having a support, a rubbing-treated alignment film, and an optically anisotropic layer containing a liquid crystal compound in this order,
The optically anisotropic layer contains at least one onium compound represented by the following general formula (I):

In general formula (I), ring A represents a quaternary ammonium ion of a nitrogen-containing heterocycle; X represents an anion; L ¹ represents a divalent linking group; L ² represents a single bond or a divalent linking group. represents a group; Y ¹ represents a divalent linking group having a 5- or 6-membered ring as a partial structure; Z represents a divalent linking group having an alkylene group of C ₂ ~ ₂₀ as a partial structure; P ¹ and P ² independently represents a monovalent substituent having a polymerizable ethylenically unsaturated group.
[2] The optical film of [1], wherein the at least one onium compound represented by the general formula (I) is a compound represented by the following general formula (I-1) or (I-2):

The definition of each symbol of general formula (I-1) and (I-2) is synonymous with each in general formula (I); L < ³ > and L < ⁴ > represent a bivalent coupling group each independently; Y ² and Y ³ are each independently a 6-membered ring optionally having a substituent; m represents 1 or 2, and when m is 2, two L ⁴ and two Y ³ are They may be the same or different; p represents an integer of 1 to 10.
[3] The onium compound represented by the general formula (I) is at least one of the compounds represented by the following general formula (I-3) or (I-4): Optical film:

The definitions of the symbols in the general formulas (I-3) and (I-4) are as defined in the general formulas (I-1) and (I-2); R ′ represents a substituent; b represents an integer of 1 to 4;
[4] The optical film according to any one of [1] to [3], wherein the alignment film is a film containing a modified or unmodified polyvinyl alcohol as a main component.
[5] The optical film according to any one of [1] to [4], wherein the optically anisotropic layer further contains a copolymer containing a repeating unit having at least one fluoroaliphatic group.
[6] The optical film according to any one of [1] to [5], wherein the alignment film side tilt angle of the molecules of the liquid crystal compound is fixed in an alignment state larger than the air interface side tilt angle.
[7] The optical film according to any one of [1] to [6], wherein a slow axis direction of the optically anisotropic layer is orthogonal to a rubbing direction of the alignment film.
[8] The optical film according to any one of [1] to [7], wherein the liquid crystal compound is a discotic liquid crystal compound.
[9] The optical film of [8], wherein the discotic liquid crystal compound is a discotic liquid crystal compound having the following formula (X) as a discotic core:

In formula (X), each R represents an organic substituent necessary for the compound of formula (X) to exhibit liquid crystallinity.
[10] The optical film according to any one of [1] to [9], wherein an addition amount of the onium compound is 0.5 to 3 parts by mass with respect to 100 parts by mass of the liquid crystal compound.
[11] The amount of the copolymer including the repeating unit having a fluoroaliphatic group is 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the liquid crystal compound. Any optical film.
[12] A polarizing plate having at least a polarizing film and the optical film of any one of [1] to [11].
[13] A liquid crystal display device having at least the polarizing plate of [12].
[14] The liquid crystal display device according to [13], which is a TN mode.
[15] A vertical alignment agent comprising an onium compound represented by the following general formula (I):

In general formula (I), ring A represents a quaternary ammonium ion of a nitrogen-containing heterocycle; X represents an anion; L ¹ represents a divalent linking group; L ² represents a single bond or a divalent linking group. represents a group; Y ¹ represents a divalent linking group having a 5- or 6-membered ring as a partial structure; Z represents a divalent linking group having an alkylene group of C ₂ ~ ₂₀ as a partial structure; P ¹ and P ² independently represents a monovalent substituent having a polymerizable ethylenically unsaturated group.

  According to the present invention, an optical film in which liquid crystal molecules are in a stable vertical alignment state at the alignment film interface and excellent in adhesion between the alignment film and the optically anisotropic layer, and a vertical alignment agent that can be used in the production thereof In addition, a polarizing plate and a liquid crystal display device including the same can be provided.

It is a cross-sectional schematic diagram of an example of the optical film of this invention.

Hereinafter, the present invention will be described in detail.
In the description of this embodiment, “parallel” or “orthogonal” means that the angle is within a strict angle of less than ± 5 °. The error from the exact angle is preferably less than 4 °, more preferably less than 3 °.
Regarding the angle, “+” means the clockwise direction, and “−” means the counterclockwise direction.
The “slow axis” means the direction in which the refractive index is maximized, and the measurement wavelength of the refractive index is a value in the visible light region (λ = 550 nm) unless otherwise specified.

  In the description of this embodiment, the term “polarizing plate” is used to mean both a long polarizing plate and a polarizing plate cut into a size incorporated in a liquid crystal device unless otherwise specified. Yes. Here, “cutting” includes “punching” and “cutting out”. In the description of the present embodiment, “polarizer” and “polarizing plate” are distinguished from each other, but “polarizing plate” is a laminate having a transparent protective film for protecting the polarizer on at least one surface of “polarizer”. It shall mean the body.

  In the description of the present embodiment, the “molecular symmetry axis” refers to a symmetry axis when the molecule has a rotational symmetry axis, but strictly requires that the molecule is rotationally symmetric. is not. In general, in a discotic liquid crystalline compound, the molecular symmetry axis coincides with an axis perpendicular to the disc surface passing through the center of the disc surface, and in a rod-like liquid crystalline compound, the molecular symmetry axis is the long axis of the molecule. Match.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. Re (λ) is measured with KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.) by making light having a wavelength of λ nm incident in the normal direction of the film. In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like. When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method. This measuring method is also partially used for measuring the average tilt angle on the alignment film side of the discotic liquid crystal molecules in the optically anisotropic layer, which will be described later, and the average tilt angle on the opposite side.
Rth (λ) is the film surface when Re (λ) is used and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) (if there is no slow axis) Measurement is performed at a total of 6 points by injecting light of wavelength λ nm from each inclined direction in steps of 10 degrees from the normal direction to 50 ° on one side with respect to the film normal direction (with any rotation direction as the rotation axis). Then, KOBRA 21ADH or WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value. In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or WR after changing its sign to negative. The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Rth can also be calculated from the following formula (A) and formula (III) based on the value, the assumed value of the average refractive index, and the input film thickness value.

なお、上記のＲｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値をあらわす。また、式（Ａ）におけるｎｘは、面内における遅相軸方向の屈折率を表し、ｎｙは、面内においてｎｘに直交する方向の屈折率を表し、ｎｚは、ｎｘ及びｎｙに直交する方向の屈折率を表す。
Ｒｔｈ＝｛（ｎｘ＋ｎｙ）／２−ｎｚ｝×ｄ・・・・・・・・・・・式（ＩＩＩ）

Note that Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In the formula (A), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz is the direction orthogonal to nx and ny. Represents the refractive index.
Rth = {(nx + ny) / 2−nz} × d (formula (III))

When the film to be measured is a film that cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λ) is calculated by the following method. Rth (λ) is from −50 ° to the normal direction of the film, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotary axis). Measured at 11 points by making light of wavelength λ nm incident in 10 ° steps up to + 50 °, and based on the measured retardation value, average refractive index assumption value and input film thickness value. KOBRA 21ADH or WR is calculated. In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. If the average refractive index is not known, it can be measured with an Abbe refractometer. Examples of the average refractive index values of main optical films are given below:
Cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).
The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.
The measurement wavelength of the refractive index is a value at λ = 550 nm in the visible light region unless otherwise specified, and the measurement wavelength of Re and Rth is 550 nm unless otherwise specified.

(Measurement of tilt angle)
In an optically anisotropic layer in which a discotic liquid crystalline compound is aligned, the tilt angle on one surface of the optically anisotropic layer (the physical target axis in the discotic liquid crystalline compound forms the interface of the optically anisotropic layer) It is difficult to directly and accurately measure θ1 (the angle is the tilt angle) and the tilt angle θ2 of the other surface. Therefore, in this specification, θ1 and θ2 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 of some optical properties of the optical film.
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 including a layer containing a discotic liquid crystalline compound. Further, the minimum unit layer (assuming that the tilt angle of the discotic liquid crystalline compound is uniform in the layer) is assumed to be 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 the 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 value 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 θ1 on one surface of the isotropic layer and the tilt angle θ2 on the other surface as variables, and θ1 and θ2 are calculated.
Here, known values such as literature values and catalog values can be used for no and ne. 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.

1. TECHNICAL FIELD The present invention relates to an optical film having a transparent support, an alignment film, and an optically anisotropic layer. The optical film of the present invention is characterized in that the optically anisotropic layer contains a liquid crystal compound and an onium compound represented by the following formula (I). In the present specification, “containing the onium compound represented by the formula (I)” means not only the state in which the onium compound of the formula (I) is contained unreacted, but also a terminal polymerizable group. Is also included in a state of being polymerized and contained in a state of being combined with other components. The same applies to the liquid crystal compound.

  As described above, the reverse hybrid alignment state has less microscopic alignment disturbance than the optically anisotropic layer in which the positive hybrid alignment is fixed, and can be said to be more useful depending on the use of the optical compensation film or the like. In order to obtain the reverse hybrid alignment state, it is necessary to vertically align the liquid crystal molecules at the alignment film interface. In order to stably align the liquid crystal molecules vertically at the alignment film interface, it is effective to use an alignment control agent exhibiting high uneven distribution at the alignment film side interface. When the agent is used, there is a problem that the adhesion at the interface between the optically anisotropic layer and the alignment film is lowered.

  As a result of intensive studies by the present inventors, the onium compound represented by the following general formula (I) having a specific structure is used for forming an optically anisotropic layer, whereby liquid crystal molecules are stably vertically aligned at the alignment film interface. It has been found that it can be oriented and the adhesion between the optically anisotropic layer and the alignment film interface can also be improved.

FIG. 1 shows a schematic cross-sectional view of an example of the optical film of the present invention. In FIG. 1, the liquid crystal molecules LC are discotic liquid crystal molecules, but are not limited thereto.
The optical film shown in FIG. 1 has a support 1 made of a polymer film or the like, an alignment film 2 and an optically anisotropic layer 3. In the optically anisotropic layer 3, the liquid crystal molecules LC are aligned at an angle (tilt angle) βa between the disk surface and the surface of the alignment film 2 in the vicinity of the interface A with the alignment film 2. Further, in the optically anisotropic layer 3, the liquid crystal molecules LC are aligned in the vicinity of the air interface B at an angle (tilt angle) βb formed by the disk surface and the layer surface B. The tilt angle βa of the alignment film interface A and the tilt angle βb of the air interface B satisfy the relationship βb <βa, that is, the liquid crystal molecules LC are fixed in the reverse hybrid alignment state.
The reverse hybrid alignment state can reduce the micro-alignment misalignment due to the alignment disorder of the liquid crystal molecules LC than the normal hybrid alignment state (βa <βb). The micro-alignment axis misalignment causes a decrease in front contrast when used in a liquid crystal display device as an optical compensation member. The optical film of the present invention has an advantage that it contributes to optical compensation without lowering the front contrast.

As shown in FIG. 1, the surface of the alignment film 2 is rubbed along the rubbing direction R. Conventionally, when molecules of a liquid crystal compound are aligned on the rubbing treatment surface of the alignment film, the molecules are generally aligned with the disk surface parallel to the rubbing direction. However, in the present invention, the molecules of a predetermined liquid crystal compound are aligned in the presence of two predetermined additives, so that the discotic liquid crystal molecules LC in the vicinity of the alignment film interface A rub the disk surface. It is oriented at a tilt angle βa perpendicular to the direction R. As a result, the slow axis S of the optically anisotropic layer appears in a direction orthogonal to the rubbing direction R.
In continuous production, a rubbing treatment is performed in the longitudinal direction while conveying a support which is a long polymer film. That is, the rubbing direction R coincides with the transport direction (longitudinal direction of the film). When an optically anisotropic layer is formed continuously, the slow axis S of the optically anisotropic layer appears in a direction orthogonal to the rubbing direction R as shown in FIG. As a result, when integrating with a long polarizing film, it can be bonded while keeping the longitudinal direction coincident. In the conventional reverse hybrid, for example, the discotic liquid crystal molecules are aligned at the interface of the alignment film with the disk surface parallel to the rubbing direction. The present invention can solve such an adverse effect.

  In an example of the optical film of the present invention, the tilt angle βa of the liquid crystal molecules at the alignment film interface is 90 to 70 ° (preferably 90 to 80 °); on the other hand, the tilt angle βb at the air interface is 0 to 30 °. (Preferably 0 to 20 °). The reverse hybrid alignment in which the tilt angle of each interface is in the above range is suitable for viewing angle compensation of a TN mode liquid crystal display device.

According to the embodiment shown in FIG. 1, the effect of improving the adhesion between the optically anisotropic layer and the alignment film, which is the effect of the present invention, is obtained, and the optical anisotropy in which the hybrid alignment state of the conventional liquid crystal compound is fixed. It is possible to reduce the micro-alignment disorder of the layer and the resulting micro-alignment misalignment. That is, according to the embodiment of FIG. 1, the adhesion can be improved, and the decrease in front contrast caused by the optical film having the optically anisotropic layer in which the hybrid alignment state of the liquid crystal compound is fixed can be reduced.
However, this invention is not limited to the example shown in FIG. 1, For example, the optical film etc. which have the optically anisotropic layer formed by fixing the vertical alignment state of a liquid crystal compound may be sufficient.

Hereinafter, the material and manufacturing method used for manufacturing the optical film of the present invention will be described in detail.
(1) Optically anisotropic layer The optical film of the present invention is characterized in that the optically anisotropic layer containing a liquid crystal compound contains at least one onium compound represented by the following general formula (I). The onium compound acts as a vertical alignment agent for promoting vertical alignment at the alignment film interface of the liquid crystal compound, and also contributes to improving the adhesion at the interface between the optically anisotropic layer and the alignment film. The optically anisotropic layer also contains an air interface side orientation control agent (for example, a copolymer containing a repeating unit having a fluoroaliphatic group) for controlling the orientation on the air interface side, if necessary. May be.

(1) -1 Vertical alignment agent (onium compound represented by general formula (I))
The onium compound represented by the general formula (I) is added for the purpose of controlling the alignment of the liquid crystal compound at the alignment film interface, and has the effect of increasing the tilt angle in the vicinity of the alignment film interface of the molecules of the liquid crystal compound.

In general formula (I), ring A represents a quaternary ammonium ion composed of a nitrogen-containing heterocycle, X represents an anion; L ¹ represents a divalent linking group; L ² represents a single bond or a divalent group. Y ¹ represents a divalent linking group having a 5- or 6-membered ring as a partial structure; Z represents a divalent linking group having 2 to 20 alkylene groups as a partial structure; P ¹ and P ² independently represents a monovalent substituent having a polymerizable ethylenically unsaturated group.

  Ring A represents a quaternary ammonium ion composed of a nitrogen-containing heterocyclic ring. Examples of ring A include pyridine ring, picoline ring, 2,2′-bipyridyl ring, 4,4′-bipyridyl ring, 1,10-phenanthroline ring, quinoline ring, oxazole ring, thiazole ring, imidazole ring, pyrazine ring , Triazole ring, tetrazole ring and the like, preferably quaternary imidazolium ion and quaternary pyridinium ion.

  X represents an anion. Examples of X include a halogen anion (for example, fluorine ion, chlorine ion, bromine ion, iodine ion, etc.), sulfonate ion (for example, methanesulfonate ion, trifluoromethanesulfonate ion, methylsulfate ion, vinylsulfonate ion) , Allyl sulfonate ion, p-toluene sulfonate ion, p-chlorobenzene sulfonate ion, p-vinylbenzene sulfonate ion, 1,3-benzene disulfonate ion, 1,5-naphthalene disulfonate ion, 2,6- Naphthalenedisulfonate ion), sulfate ion, carbonate ion, nitrate ion, thiocyanate ion, perchlorate ion, tetrafluoroborate ion, picrate ion, acetate ion, benzoate ion, p-vinylbenzoate ion, formate ion The trifle B acetate ion, phosphoric acid ion (e.g., hexafluorophosphate ion), such as a hydroxide ion. Preferred are halogen anions, sulfonate ions, and hydroxide ions. In particular, chlorine ion, bromine ion, iodine ion, methanesulfonic acid ion, vinylsulfonic acid ion, p-toluenesulfonic acid ion, and p-vinylbenzenesulfonic acid ion are preferable.

L ¹ represents a divalent linking group. Examples of L ¹ include an alkylene group, —O—, —S—, —CO—, —SO ₂ —, —NRa— (where Ra is an alkyl group having 1 to 5 carbon atoms or a hydrogen atom. ), A divalent linking group having 1 to 20 carbon atoms, which is a combination with an alkenylene group, an alkynylene group or an arylene group. L ¹ is preferably -AL-, -O-AL-, -CO-O-AL-, or -O-CO-AL- having 1 to 10 carbon atoms, and -AL having 1 to 10 carbon atoms. -And -O-AL- are more preferable, and -AL- and -O-AL- having 1 to 5 carbon atoms are most preferable. AL represents an alkylene group.

L ² represents a single bond or a divalent linking group. Examples of L ² include an alkylene group, —O—, —S—, —CO—, —SO ₂ —, —NRa— (where Ra is an alkyl group having 1 to 5 carbon atoms or a hydrogen atom. ), A divalent linking group having 1 to 10 carbon atoms consisting of a combination with an alkenylene group, an alkynylene group or an arylene group, a single bond, —O—, —O—CO—, —CO—O—, —O -AL-O-, -O-AL-O-CO-, -O-AL-CO-O-, -CO-O-AL-O-, -CO-O-AL-O-CO-, -CO -O-AL-CO-O-, -O-CO-AL-O-, -O-CO-AL-O-CO-, -O-CO-AL-CO-O-, and the like can be given. AL represents an alkylene group. L ² is preferably a single bond, -AL- having 1 to 10 carbon atoms, -O-AL-, or -NRa-AL-O-, a single bond, -AL- having 1 to 5 carbon atoms, —O—AL— and —NRa—AL—O— are more preferable, and —O—AL— and —NRa—AL—O— having a single bond and 1 to 5 carbon atoms are most preferable.

Y ¹ represents a divalent linking group having a 5- or 6-membered ring as a partial structure. Examples of Y ¹ include a cyclohexyl ring, an aromatic ring or a heterocyclic ring. Examples of the aromatic ring include a benzene ring, an indene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, a biphenyl ring, and a pyrene ring, and a benzene ring, a biphenyl ring, and a naphthalene ring are particularly preferable. The hetero atom constituting the hetero ring is preferably a nitrogen atom, an oxygen atom or a sulfur atom. For example, a furan ring, thiophene ring, pyrrole ring, pyrroline ring, pyrrolidine ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole Ring, imidazole ring, imidazoline ring, imidazolidine ring, pyrazole ring, pyrazoline ring, pyrazolidine ring, triazole ring, furazane ring, tetrazole ring, pyran ring, dioxane ring, dithiane ring, thiine ring, pyridine ring, piperidine ring, oxazine ring Morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring and triazine ring. The heterocycle is preferably a 6-membered ring. The divalent linking group having a 5- or 6-membered ring represented by Y ¹ as a partial structure may further have a substituent.

  Examples of the substituent include a halogen atom, a cyano group, an alkyl group having 1 to 12 carbon atoms (more preferably 1 to 10, more preferably 1 to 5), and 2 to 12 carbon atoms (more preferably). An alkenyl group having 2 to 10 and more preferably 2 to 5), an alkoxy group having 1 to 12 carbon atoms (more preferably 1 to 10, more preferably 1 to 5), and the like can be mentioned. The alkyl group and the alkoxy group have an acyl group having 2 to 12 carbon atoms (more preferably 2 to 10 and more preferably 2 to 5) or 2 to 12 carbon atoms (more preferably 2 to 10 and more preferably). May be substituted with an acyloxy group of 2-5). The acyl group is represented by —CO—R, the acyloxy group is represented by —O—CO—R, and R is an aliphatic group (alkyl group, substituted alkyl group, alkenyl group, substituted alkenyl group, alkynyl group, substituted alkynyl group) or aromatic. Group (aryl group, substituted aryl group). R is preferably an aliphatic group, and more preferably an alkyl group or an alkenyl group.

The divalent linking group represented by Y ¹ is preferably a divalent linking group having two or more 5- or 6-membered rings, and preferably has a structure in which two or more rings are connected by a linking group. More preferred. Examples of linking groups include linking groups represented by L ¹ and L ^2, and —C≡C—, —CH═CH—, —CH═N—, —N═CH—, —N═N— and the like. Can be mentioned.

Z represents a divalent linking group having a combination of —O—, —S—, —CO—, and —SO ₂ — with a C 2-20 alkylene group as a partial structure, and an alkylene group May have a substituent. Examples of the divalent linking group include an alkyleneoxy group and a polyalkyleneoxy group. The number of carbon atoms of the alkylene group represented by Z is more preferably 2 to 16, more preferably 2 to 12, and particularly preferably 2 to 8.

P ¹ and P ² each independently represent a monovalent substituent having a polymerizable ethylenically unsaturated group. Examples of the monovalent substituent having the polymerizable ethylenically unsaturated group include the following formulas (M-1) to (M-8). That is, the monovalent substituent having a polymerizable ethylenically unsaturated group may be a substituent consisting only of an ethenyl group as in (M-8).

In formulas (M-3) and (M-4), R represents a hydrogen atom or an alkyl group, preferably a hydrogen atom or a methyl group. Among the above formulas (M-1) to (M-8), (M-1), (M-2) and (M-8) are preferable, and (M-1) or (M-8) is more preferable. . In particular, (M-1) is preferable as P ¹ . P ² is preferably (M-1) or (M-8), and in the compound in which ring A is a quaternary imidazolium ion, P ² is (M-8) or (M-1). And in compounds where ring A is a quaternary pyridinium ion, P ² is preferably (M-1).

一般式（Ｉ−１）及び（Ｉ−２）の各記号の定義は、一般式（Ｉ）中のそれぞれと同義であり；Ｌ³及びＬ⁴はそれぞれ独立に二価の連結基を表し；Ｙ²及びＹ³はそれぞれ独立に置換基を有していてもよい６員環であり；ｍは１又は２を表し、ｍが２の場合、二つのＬ⁴および二つのＹ³は、互いに同一でも異なっていてもよく；ｐは１〜１０の整数を表す。 The onium compounds represented by the general formula (I) include onium compounds represented by the following general formulas (I-1) and (I-2).

The definition of each symbol of general formula (I-1) and (I-2) is synonymous with each in general formula (I); L < ³ > and L < ⁴ > represent a bivalent coupling group each independently; Y ² and Y ³ are each independently a 6-membered ring optionally having a substituent; m represents 1 or 2, and when m is 2, two L ⁴ and two Y ³ are They may be the same or different; p represents an integer of 1 to 10.

L ³ represents a divalent linking group, and examples of L ³ include a single bond, —O—, —O—CO—, —CO—O—, —O—AL—O—, —O—AL. -O-CO-, -O-AL-CO-O-, -CO-O-AL-O-, -CO-O-AL-O-CO-, -CO-O-AL-CO-O-, -O-CO-AL-O-, -O-CO-AL-O-CO-, and -O-CO-AL-CO-O-. Note that AL represents an alkylene group having 1 to 10 carbon atoms. L ³ represents a single bond, —O—, —O—AL—O—, —O—AL—O—CO—, —O—AL—CO—O—, —CO—O—AL—O—, — CO-O-AL-O-CO-, -CO-O-AL-CO-O-, -O-CO-AL-O-, -O-CO-AL-O-CO-, -O-CO- AL-CO-O- is preferable, a single bond or -O- is more preferable, and -O- is most preferable.

L ⁴ represents a divalent linking group, and examples of L ⁴ include a single bond, —O—, —O—CO—, —CO—O—, —C≡C—, —CH═CH—, -CH = N-, -N = CH-, -N = N-, -NH-CO-, -CO-NH-. L ⁴ is preferably a single bond, —O—CO—, —CO—O—, —C≡C—, —NH—CO—, —CO—NH—, and preferably a single bond, —O—CO—, —CO. —O— is more preferable, and —O—CO— and —CO—O— are most preferable.

Y ² and Y ³ each independently represent a 6-membered ring optionally having a substituent, and the 6-membered ring includes an aliphatic ring, an aromatic ring (benzene ring) and a heterocyclic ring. Examples of the aliphatic 6-membered ring include a cyclohexane ring, a cyclohexene ring, and a cyclohexadiene ring. Examples of the aromatic ring include a benzene ring, an indene ring, a naphthalene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, a biphenyl ring, and a pyrene ring. Examples of 6-membered heterocycles include pyran ring, dioxane ring, dithiane ring, thiine ring, pyridine ring, piperidine ring, oxazine ring, morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring, triazine ring Etc. Further, another 6-membered ring or a 5-membered ring may be condensed with the 6-membered ring. Y ² and Y ³ are preferably a cyclohexane ring, a pyridine ring, a pyrimidine ring or a benzene ring, more preferably a pyrimidine ring or a benzene ring, and most preferably a benzene ring.

Examples of the substituent include a halogen atom, a cyano group, an alkyl group having 1 to 12 carbon atoms (more preferably 1 to 10, more preferably 1 to 5), an alkoxy group having 1 to 12 carbon atoms, and the like. Is mentioned. The alkyl group and the alkoxy group may be substituted with an acyl group having 2 to 12 carbon atoms or an acyloxy group having 2 to 12 carbon atoms. The acyl group is represented by —CO—R, the acyloxy group is represented by —O—CO—R, and R is an aliphatic group (alkyl group, substituted alkyl group, alkenyl group, substituted alkenyl group, alkynyl group, substituted alkynyl group) or aromatic. Group (aryl group, substituted aryl group). R is preferably an aliphatic group, and more preferably an alkyl group or an alkenyl group.
In formulas (I-1) and (I-2), at least one Y ³ is preferably a substituted benzene ring, preferably a benzene ring having one or more halogen groups, alkyl groups or alkoxy groups. Is more preferable, and a benzene ring having two or more alkyl groups or alkenyl groups is more preferable.

m represents an integer of 1 or 2, and when m is 2, two L ⁴ and two Y ³ may be different.

C _p H _2p represents a chain alkylene group which may have a branched structure. C _p H _2p is preferably a linear alkylene group (— (CH ₂ ) _p —).

  p represents an integer of 1 to 10, more preferably 1 to 5, and most preferably 1 to 2.

The onium compounds represented by the general formula (I) include onium compounds represented by the following general formulas (I-3) and (I-4).

  The definition of each symbol of general formula (I-3) and (I-4) is synonymous with each in general formula (I-1) or (I-2); R 'represents a substituent; b represents an integer of 1 to 4.

Examples of R ′ are the same as the examples of the substituent of the 6-membered ring represented by Y ² and Y ³ in general formula (I-1) or (I-2), and the preferred ranges are also the same. . That is, R ′ is preferably a halogen group, an alkyl group or an alkoxy group.
b represents an integer of 1 to 4, more preferably 1 to 3, and still more preferably 2 to 3.

  Specific examples of the compound represented by the general formula (I) are shown below.

  The onium compound of the general formula (I) can be generally synthesized by alkylating a nitrogen-containing heterocycle (Menstokin reaction).

(1) -2 Liquid crystal compound The optically anisotropic layer contains a liquid crystal compound.
The liquid crystal compound used for forming the optically anisotropic layer may be a rod-like liquid crystal compound or a discotic liquid crystal compound. Among them, a discotic liquid crystal compound is preferable, a triphenylene compound, and a 3-substituted benzene compound in which 1, 3, and 5 positions of benzene are substituted are preferable, and particularly, for example, a tri-substituted compound having the following formula (X) as a discotic core Benzene compounds are preferred.

In formula (X), R represents an organic substituent necessary for the compound of formula (X) to exhibit liquid crystallinity, and has the same meaning as R ¹ , R ² and R ³ in formula (1).

  Since the discotic liquid crystal compound represented by the formula (X) exhibits high Δn and low wavelength dispersion, an optical film having an optically anisotropic layer formed by fixing the molecular orientation of the compound is a liquid crystal. It is highly useful as an optical compensation film for display devices. Among them, an optical film having an optically anisotropic layer formed by fixing molecules of the discotic liquid crystal compound of formula (X) to “vertical alignment” or “reverse hybrid alignment” is an optical compensation film for liquid crystal display devices. Especially useful as.

  The compound of formula (X) is described in detail in JP-A-2002-90545, JP-A-2006-276203, and Japanese Patent Application No. 2009-68293, and the same applies to specific examples. .

  The discotic liquid crystalline compound preferably has a polymerizable group so that it can be fixed by polymerization. For example, a structure in which a polymerizable group is bonded as a substituent to a discotic core of a discotic liquid crystalline compound is conceivable. However, when a polymerizable group is directly connected to the discotic core, the alignment state is maintained in the polymerization reaction. It becomes difficult. Therefore, a structure having a linking group between the discotic core and the polymerizable group is preferable. That is, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula (II).

In the formula, Y ¹¹ , Y ¹² and Y ¹³ each independently represent a methine or nitrogen atom which may be substituted; L ¹ , L ² and L ³ each independently represent a single bond or a divalent linking group. H ¹ , H ² and H ³ each independently represent a group of the general formula (IA) or (IB); R ¹ , R ² and R ³ each independently represent the following general formula Represents (IR);

In the general formula (IA), YA ¹ and YA ² each independently represents a methine or nitrogen atom; XA represents an oxygen atom, a sulfur atom, methylene or imino; * represents the above general formula (1) Represents a position bonded to the L ^{1 to} L ³ side; ** represents a position bonded to the R ^{1 to} R ³ side in the general formula (1);

In the general formula (IB), YB ¹ and YB ² each independently represent a methine or nitrogen atom; XB represents an oxygen atom, a sulfur atom, methylene or imino; * represents the above general formula (1) Represents a position bonded to the L ^{1 to} L ³ side; ** represents a position bonded to the R ^{1 to} R ³ side in the general formula (1);

General formula (IR)
*-(-L ²¹ -Q ² ) _n1 -L ²² -L ²³ -Q ¹
In the general formula (IR), * represents a position bonded to the H ^{1 to} H ³ side in the general formula (1); L ²¹ represents a single bond or a divalent linking group; Q ² is at least 1 It represents the type of divalent group having a cyclic structure (cyclic group); n1 represents an integer of 0 to 4; L ²² is, ** - O -, ** - O-CO -, ** - CO -O -, ** - O-CO -O -, ** - S -, ** - NH -, ** - SO 2 -, ** - CH 2 -, ** - CH = CH- or ** —C≡C—; L ²³ represents —O—, —S—, —C (═O) —, —SO ₂ —, —NH—, —CH ₂ —, —CH═CH— and —C. Represents a divalent linking group selected from the group consisting of ≡C— and combinations thereof; Q ¹ represents a polymerizable group or a hydrogen atom;

  For preferred ranges of the respective symbols of the trisubstituted benzene-based discotic liquid crystalline compound represented by the formula (II) and specific examples of the compound of the formula (II), refer to paragraph [0013] of JP 2010-244038 A. ] To [0077], [Chemical 13] to [Chemical 43] of [0052] of JP-A-2006-76992, and [Chemical 13] to [0063] of [0040] of JP-A-2007-2220. The description of Chemical Formula 36] can be referred to. However, the discotic liquid crystalline compound that can be used in the present invention is not limited to the trisubstituted benzene-based discotic liquid crystalline compound of the formula (II).

  Examples of the discotic liquid crystal compound include a triphenylene compound, and examples of the triphenylene compound include the compounds described in paragraphs [0062] to [0067] of JP-A-2007-108732. It is not limited to these.

  Examples of the discotic liquid crystal compound include a disubstituted benzene compound substituted at the 1,3-position of benzene. Examples of the disubstituted benzene compound include paragraphs [0020] to [0064] of Japanese Patent Application No. 2009-68293. However, the present invention is not limited to these.

  Other examples of discotic compounds that can be used in the present invention include benzene derivatives (described in the research report of C. Destrade et al., Mol. Cryst. 71, 111 (1981)), and truxene derivatives (C. Destrade). Et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990)), cyclohexane derivatives (B. Kohne et al., Angew. Chem. 96, 70 (1984)) and azacrown or phenylacetylene macrocycles (J.M. Lehn et al., J. Chem. Commun., 1794 (1985), J. Zhang et al., J. Am. Chem. Soc., 116, 265 Page (1994) described) are included.

  Examples of rod-like liquid crystalline compounds that can be used for forming the optically anisotropic layer include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexane. , Cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only the above low-molecular liquid crystalline compounds but also high-molecular liquid crystalline compounds can be used. It is more preferable to fix the alignment of the rod-like liquid crystal compound by polymerization. As the liquid crystalline compound, those having a partial structure capable of causing polymerization or crosslinking reaction by actinic rays, electron beams, heat, or the like are suitably used. The number of the partial structures is preferably 1 to 6, more preferably 1 to 3. As the polymerizable rod-like liquid crystalline compound, Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. No. 5,770,107, International Publication WO95 / 22586. No. 95/24455, No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, and No. 7-110469. 11-80081 and JP-A-2001-328773, etc. can be used.

  The alignment state of the liquid crystal molecules in the optically anisotropic layer is not particularly limited, but a vertical alignment state or a reverse hybrid alignment state is preferable. In addition, when the discotic liquid crystal molecules are aligned vertically or reversely hybrid, the orientation of the discotic molecules is such that the disc surface and the direction in which the alignment film is rubbed are parallel (hereinafter also referred to as “parallel alignment”). ) And the case of orientation (hereinafter also referred to as “orthogonal orientation”) such that the normal direction of the disc surface and the rubbing direction are parallel to each other. In actual production, since continuous production is used, rubbing is generally performed along the lengthwise direction of the film. Therefore, when it is considered that the long polarizer and the long direction are bonded together, “orthogonal alignment” is desired instead of “parallel alignment”.

(1) -3 Copolymer containing a repeating unit having a fluoroaliphatic group A copolymer containing a repeating unit having a fluoroaliphatic group is mainly represented by a liquid crystal compound (for example, the general formula (1)). It is added for the purpose of controlling the orientation of the discotic liquid crystal compound) at the air interface, and has the effect of reducing the tilt angle of the molecules of the discotic liquid crystal compound in the vicinity of the air interface.

  A copolymer containing a repeating unit having a fluoroaliphatic group includes a structural unit derived from a fluoroaliphatic group-containing monomer described in [0051] to [0052] of JP-A-2008-257205, and [0055] to [ [0056] Copolymers (preferred examples [0054]) comprising constituent units derived from the monomers described in JP-A-2008-257205, JP-A-2008-111110, JP-A-2007-272185, and JP-A-2007-272185. The compounds described in each publication of 2007-217656 are mentioned.

(1) -4 Preparation of Composition The optically anisotropic layer is formed from a composition containing at least a liquid crystal compound and an onium compound represented by the general formula (I). In the composition, a liquid crystal compound is used as a main component. Although there is no restriction | limiting in particular about compounding quantity, The mass ratio with respect to the discotic liquid crystal compound of each compound of the onium compound represented by the said general formula (I), and the copolymer containing the repeating unit which has a fluoro aliphatic group, It is preferable to adjust in order to obtain a disordered alignment state. In this respect, the addition amount of the onium compound of the formula (I) is preferably 0.5 to 3 parts by mass, and more preferably 1 to 3 parts by mass with respect to 100 parts by mass of the liquid crystal compound.
On the other hand, the addition amount of the compound containing a copolymer containing a repeating unit having a fluoroaliphatic group is preferably 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the liquid crystal compound. More preferably, it is 1.0 part by mass.
When the addition amount of the copolymer containing a repeating unit having a fluoroaliphatic group is less than 0.2 parts by mass, the variation of the tilt angle with respect to the aging temperature may increase, which may be unfavorable for production suitability. The surface condition may deteriorate due to wind unevenness during drying. If it exceeds 2.0 parts by mass, the liquid crystal compound may easily cause alignment failure.

  The composition can be prepared as a coating solution. As a solvent used for preparation of a coating liquid, an organic solvent is preferable. 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 Is preferred. The said organic solvent may be used individually by 1 type, and may use 2 types together. It is preferable that the surface tension of the coating solution is 25 mN / m or less (more preferably 22 mN / m or less) because an optically anisotropic layer with high uniformity can be formed.

  Moreover, it is preferable that the said composition is curable, and it is preferable to contain the polymerization initiator in the said aspect. The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator, but a photopolymerization initiator is preferable from the viewpoint of easy control. Examples of photopolymerization initiators that generate radicals by the action of light include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670) and acyloin ethers (described in US Pat. No. 2,448,828). ), Α-hydrocarbon substituted aromatic 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), triarylimidazole dimers and p-amino Combination with phenyl ketone (described in US Pat. No. 3,549,367), acridine and phenazine compounds (described in JP-A-60-105667, US Pat. No. 4,239,850) and oxadiazole compounds (US Pat. No. 4,221,970) Description), acetophenone series Compounds, benzoin ether compounds, benzyl compounds, benzophenone compounds, thioxanthone compounds and the like are preferable.

  In addition to a polymerization initiator, a sensitizer may be used for the purpose of increasing sensitivity. Examples of the sensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, thioxanthone and the like. Multiple photopolymerization initiators may be combined, and the amount used is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the solid content of the coating solution. The light irradiation for the polymerization of the liquid crystal compound preferably uses ultraviolet rays.

  Apart from the polymerizable liquid crystal compound, the composition may contain a non-liquid crystalline polymerizable monomer. As the polymerizable monomer, a compound having a vinyl group, a vinyloxy group, an acryloyl group or a methacryloyl group is preferable. Note that it is preferable to use a polyfunctional monomer having two or more polymerizable reactive functional groups, for example, ethylene oxide-modified trimethylolpropane acrylate because durability is improved. Since the non-liquid crystalline polymerizable monomer is a non-liquid crystalline component, the addition amount thereof does not exceed 15% by mass with respect to the liquid crystal compound, and is preferably about 0 to 10% by mass.

(1) -5 Formation of optically anisotropic layer An example of a method for forming the optically anisotropic layer is as follows.
A composition containing at least the liquid crystal compound prepared as a coating liquid and the onium compound represented by the general formula (I) is applied to the rubbing-treated surface of the alignment film. Application methods include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, wire bar method, etc. A well-known coating method is mentioned.

  The coating film of the composition is dried to bring the liquid crystal compound molecules into a desired alignment state. At this time, it is preferable to heat. In particular, when heated at 50 to 120 ° C., for example, the molecules of the discotic liquid crystal compound can be in a reverse hybrid alignment state, and the slow axis can be expressed in a direction perpendicular to the rubbing direction. It can be formed stably. When heated below 50 ° C., the orientation is more disturbed. On the other hand, when heated above 120 ° C., the reverse axis is obtained, but the slow axis is in an aligned state that is parallel to the rubbing direction. Tend. It is more preferable to heat at 70-100 degreeC. Further, the heating time is preferably about 60 to 300 seconds, and more preferably about 90 to 300 seconds.

After the molecules of the liquid crystal compound are brought into a desired alignment state, they are cured by polymerization, the alignment state is fixed, and an optically anisotropic layer is formed. X-rays, electron beams, ultraviolet rays, visible rays, or infrared rays (heat rays) can be used as the irradiation light. Among these, it is preferable to use ultraviolet rays. The light source is preferably a low-pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), high-pressure discharge lamp (high-pressure mercury lamp, metal halide lamp) or short arc discharge lamp (super-high pressure mercury lamp, xenon lamp, mercury xenon lamp). Used. Exposure dose is preferably about 50~6000mJ / cm ^2, and still more preferably about 100 to 2000 mJ / cm ^2. In order to control the alignment in a short time, it is preferable to irradiate light while heating. The heating temperature is preferably about 40 to 140 ° C.

  The thickness of the optically anisotropic layer formed in this manner is not particularly limited, but is preferably 0.1 to 10 μm, and more preferably 0.5 to 5 μm.

(2) Alignment film In the present invention, modified or unmodified polyvinyl alcohol is used as the material of the alignment film. Not only a known material for the vertical alignment film but also a known material for the horizontal alignment film can be selected. Modified or unmodified polyvinyl alcohol is also used as a horizontal alignment film. By adding the onium compound of the above formula (I) to the composition for forming an optically anisotropic layer, the onium compound and the alignment film are used. The liquid crystal molecules can be vertically aligned at the interface of the alignment film by the action of and the action of the onium compound and the liquid crystal compound. Among the modified polyvinyl alcohols, it is preferable to use an alignment film containing a modified polyvinyl alcohol containing a unit having a polymerizable group, since the adhesion to the optically anisotropic layer can be further improved. Polyvinyl alcohol in which at least one hydroxyl group is substituted with a group having a vinyl moiety, an oxiranyl moiety, or an aziridinyl moiety is preferable. Is preferred.

  The alignment film that can be used in the present invention has a rubbing treatment surface that has been subjected to rubbing treatment. In the present invention, a general rubbing processing method can be used. For example, it can be carried out by rubbing the surface of the alignment film with a rubbing roll. In an aspect in which an alignment film is continuously formed on a support made of a long polymer film, the rubbing treatment direction (rubbing direction) coincides with the longitudinal direction of the polymer film from the viewpoint of production suitability. Is preferred.

(3) Support body There is no restriction | limiting in particular about a support body. Various polymer films can be used. An example is a polymer film that is transparent and has small optical anisotropy, but is not limited thereto. Here, that the support is transparent means that the light transmittance is 80% or more. Further, the small optical anisotropy specifically means that the in-plane retardation (Re) is 20 nm or less, and more preferably 10 nm or less. The transparent support may be a long and roll-shaped shape, or a size of the final product, for example, a rectangular sheet shape. It is preferable to use a long polymer film wound up in a roll shape as a support, continuously form an alignment film and an optically anisotropic layer, and then cut into a required size.

  Examples of polymer films that can be used as the support include films of cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate, cyclic polyolefin, and the like. A cellulose acylate film is preferred, and a cellulose acetate film is more preferred. When a cellulose acylate film is used, a decrease in front contrast is further suppressed.

  Although there is no restriction | limiting in particular about the polymer film thickness used as a support body, Generally, it is preferable that it is 20-500 micrometers, and it is more preferable that it is 30-200 micrometers.

  The polymer film for the support may be a film produced by either a solution casting method or a melt casting method. About a cellulose acylate film, the film manufactured by the solvent cast method is preferable. Further, in order to improve the adhesion with the alignment film provided on the polymer film used as the transparent support, surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment, Saponification treatment) may be performed. An adhesive layer (undercoat layer) may be provided on the transparent support.

2. Polarizing plate The present invention also relates to a polarizing plate having at least a polarizing film and the optical film of the present invention. One embodiment of the polarizing plate of the present invention is a polarizing plate in which the optical film of the present invention is laminated on one surface of a polarizing film and a protective film is laminated on the other surface. In this aspect, it is preferable that the back surface (the surface on which the alignment film and the optically anisotropic layer are not formed) of the support of the optical film of the present invention is bonded to one surface of the polarizing film. There is no restriction | limiting in particular about the protective film bonded on the other surface, It is preferable to select from the example of the polymer film which can be utilized as the said support body. A preferred example of the protective film is a cellulose acylate film such as a triacetyl cellulose film.

  Examples of the polarizing film include an iodine-based polarizing film, a dye-based polarizing film using a dichroic dye, and a polyene-based polarizing film, and any of them may be used in the present invention. The iodine polarizing film and the dye polarizing film are generally produced using a polyvinyl alcohol film.

  A long polarizing film and a long optical film of the present invention can be continuously bonded to produce a polarizing plate. As described above, in the production of an optical film, it is preferable to perform a rubbing treatment along the longitudinal direction of the support from the viewpoint of production suitability. In the optical film of the present invention, the slow axis of the optically anisotropic layer is in a direction orthogonal to the rubbing direction, that is, in a direction orthogonal to the longitudinal direction. Therefore, when laminating the optical film of the present invention with the longitudinal direction coincided when pasting with the long polarizing film, the slow axis of the optically anisotropic layer and the absorption axis of the polarizing film are orthogonal to each other. The polarizing plate can be easily and continuously produced.

3. Liquid crystal display device TECHNICAL FIELD This invention relates also to the liquid crystal display device which has the polarizing plate of this invention. The optical film of the present invention is suitable for optical compensation of a TN liquid crystal display device. Therefore, a preferred embodiment of the liquid crystal display device of the present invention is a TN type liquid crystal display device. TN mode liquid crystal cells and TN type liquid crystal display devices have been well known. The Δn · d of the liquid crystal cell is about 300 to 500 nm. The polarizing plate of the present invention is preferably disposed with the optical film of the present invention facing the liquid crystal cell. If there is a macro disturbance in the optically anisotropic layer used for optical compensation, for example, it contributes to a decrease in the front contrast of the liquid crystal display device. Since the optically anisotropic layer of the optical film of the present invention is a layer in which the reverse hybrid orientation of the discotic liquid crystal molecules is fixed, the macro alignment disorder is very small compared to the layer in which the positive hybrid is fixed. Therefore, according to the present invention, sufficient optical compensation can be achieved by the optical film of the present invention without reducing the front contrast of the 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.

1. Production of optical film (1) Production of transparent support <Preparation of support>
The following composition was put into a mixing tank and stirred while heating to 30 ° C. to dissolve each component to prepare a cellulose acylate solution.
────────────────────────────────────
Cellulose acylate solution composition (parts by mass) Inner layer Outer layer ────────────────────────────────────
Cellulose acylate with an acetylation degree of 60.9% 100 100
Triphenyl phosphate (plasticizer) 7.8 7.8
Biphenyl diphenyl phosphate (plasticizer) 3.9 3.9
Methylene chloride (first solvent) 293 314
Methanol (second solvent) 71 76
1-butanol (third solvent) 1.5 1.6
Silica fine particles (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.)
0 0.8
The following retardation increasing agent 1.3 1.3
────────────────────────────────────

  The obtained inner layer dope and outer layer dope were cast on a drum cooled to −10 ° C. using a three-layer co-casting die. With respect to 100 parts by mass of cellulose acylate, a film having a residual solvent amount of 290 parts by mass is peeled off from the drum, both ends are fixed with a pin tenter, and the draw ratio in the conveyance direction is 115% while conveying at a supply temperature of 70 ° C. When the residual solvent amount reached 40 parts by mass, drying was performed at an air supply temperature of 140 ° C. Thereafter, the cellulose acylate film is dried at a supply air temperature of 140 ° C. for 10 minutes and the residual solvent is 0.2% by mass (outer layer thickness: 3 μm, inner layer thickness: 74 μm (total thickness: 80 μm), length. : 2000 m, width: 1490 mm).

  About the produced cellulose acylate film, using an ellipsometer (M-150, manufactured by JASCO Corporation), an in-plane direction retardation value (Re) and a thickness direction retardation value (Rth) at a wavelength of 632.8 nm are used. Was measured. The slow axis was orthogonal to the transport direction, Re was 15 nm, and Rth was 100 nm.

(Alkaline saponification treatment)
After passing the cellulose acylate film through a dielectric heating roll at a temperature of 60 ° C. and raising the film surface temperature to 40 ° C., the coating amount of an alkali solution having the composition shown below is applied to one side of the film using a bar coater. It was transported for 10 seconds under a steam far-infrared heater manufactured by Noritake Co., Ltd., which was applied at 14 ml / m ² and heated to 110 ° C. Subsequently, 3 ml / m ^{2 of} pure water was applied using the same bar coater. Next, washing with a fountain coater and draining with an air knife were repeated three times, and then transported to a drying zone at 70 ° C. for 10 seconds and dried to prepare an alkali saponified cellulose acylate film.

────────────────────────────────────
Alkaline solution composition ────────────────────────────────────
Potassium hydroxide 4.7 parts by weight Water 15.8 parts by weight Isopropanol 63.7 parts by weight Surfactant SF-1: C ₁₄ H ₂₉ O (CH ₂ CH ₂ O) ₂₀ H 1.0 part by weight Propylene glycol 14. 8 parts by mass ────────────────────────────────────

  The cellulose acylate film thus produced was used as a support.

(2) Formation of Alignment Film An alignment film coating solution having the following composition was continuously applied to the saponified surface of the above prepared support with a # 14 wire bar. The alignment film was formed by drying with warm air of 60 ° C. for 60 seconds and further with warm air of 100 ° C. for 120 seconds.
────────────────────────────────────
Composition of coating solution for alignment film formation ────────────────────────────────────
Denatured polyvinyl alcohol 10 parts by weight Water 371 parts by weight Methanol 119 parts by weight Photopolymerization initiator (Irgacure 2959, manufactured by Ciba Japan) 0.3 parts by weight ─────────────── ─────────────────────

  The surface of the formed alignment film was rubbed along the longitudinal direction of the film.

(3) Formation of optically anisotropic layer An optically anisotropic layer coating solution having the following composition was applied at a coating amount of 4 ml / m ² using a bar coater. The liquid crystal compound was aligned by heating for 120 seconds at the aging temperature shown in the following table. Thereafter, the temperature is maintained, and an ultraviolet ray irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m) is irradiated with ultraviolet rays having an illuminance of 600 mW / cm ² for 4 seconds to advance the crosslinking reaction, thereby producing a liquid crystal compound. Was fixed in that orientation. Then, it was allowed to cool to room temperature and wound into a cylindrical shape to obtain a roll-shaped optical film.

────────────────────────────────────
Optically anisotropic layer coating composition ─────────────────────────────────────
100.0 parts by mass of a liquid crystal compound shown in the following table Mass parts shown in the following table Mass parts shown in the following table Copolymers containing repeating units having a fluoroaliphatic group shown in the following table Mass parts shown in the following table Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 3.0 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1.0 part by mass Methyl ethyl ketone 341.8 parts by mass ────────── ──────────────────────────

(4) Evaluation of optical film (4) -1 Orientation evaluation About each produced optical film, according to the said method using KOBRA-21ADH (made by Oji Scientific Instruments), the discotic liquid crystal compound molecule | numerator of alignment film interface The tilt angle and the tilt angle of the molecules of the discotic liquid crystal compound at the air interface were measured. The results are shown in the following table. In the following table, “vertical” represents a tilt angle of 70 ° to 90 °, and “horizontal” represents a tilt angle of 0 ° to 30 °. For ranges other than the above, the measurement angle is shown.
Moreover, about each optical film, the direction of the slow axis of the optically anisotropic layer was determined according to the said method using KOBRA-21ADH (Oji Scientific Instruments Co., Ltd. product).
The following table shows the relationship between the slow axis of the optically anisotropic layer and the rubbing direction of the alignment film.

(4) -2 Adhesion evaluation The surface on the side having the liquid crystal layer of each of the produced optical films was cut into 11 vertical and 11 horizontal cuts with a cutter knife in a total of 100 1 mm squares. A square grid was cut, and a polyester adhesive tape “No. 31B” manufactured by Nitto Denko Corporation was pressure-bonded to perform an adhesion test. The presence or absence of peeling was visually observed, and the following four-stage evaluation was performed.
◎: No peeling was observed in 100 squares ○: No peeling was observed in 100 squares within 2 squares Δ: peeling was observed in 100 squares Of 3 to 10 cm x: those in which peeling was observed in 100 cells exceeded 10 cm. The results are shown in the following table.

2. Production and Evaluation of Liquid Crystal Display (1) Production of Polarizing Plate A polyvinyl alcohol (PVA) film having a thickness of 80 μm is dyed by immersing in an aqueous iodine solution having an iodine concentration of 0.05 mass% at 30 ° C. for 60 seconds, and then While immersed in an aqueous boric acid solution having a boric acid concentration of 4 mass% for 60 seconds, the film was stretched longitudinally to 5 times the original length. Then, it was dried at 50 ° C. for 4 minutes to obtain a polarizing film having a thickness of 20 μm.
A commercially available cellulose acetate film was immersed in an aqueous sodium hydroxide solution at 55 ° C. at 1.5 mol / L, and then the sodium hydroxide was sufficiently washed away with water. Then, after being immersed for 1 minute in 35 degreeC dilute sulfuric acid aqueous solution at 0.005 mol / L, it was immersed in water and the dilute sulfuric acid aqueous solution was fully washed away. Finally, the sample was thoroughly dried at 120 ° C.
The optical film produced by the above method and a commercially available cellulose acetate film subjected to saponification treatment were combined and bonded using a polyvinyl alcohol-based adhesive so as to sandwich the polarizing film to obtain a polarizing plate. Here, it arrange | positioned so that the optically anisotropic layer of an optical film might come outside. As a commercially available cellulose acetate film, Fujitac TF80UL (manufactured by FUJIFILM Corporation) was used. At this time, since the polarizing film and the protective films on both sides of the polarizing film were produced in the form of rolls, the longitudinal directions of the roll films were parallel to each other and were bonded together. Therefore, the roll longitudinal direction of the optical film (the casting direction of the cellulose acetate film) and the polarizer absorption axis were parallel to each other.

(2) Production of TN mode liquid crystal display device A pair of polarizing plates provided in a liquid crystal display device (AL2216W, manufactured by Nippon Acer Co., Ltd.) using a TN type liquid crystal cell is peeled off, and the produced polarizing plate is used instead. Were attached to the observer side and the backlight side one by one with an adhesive such that the optical film was on the liquid crystal cell side, that is, the optically anisotropic layer was most on the liquid crystal cell side. At this time, the transmission axis of the polarizing plate on the observer side and the transmission axis of the polarizing plate on the backlight side were arranged orthogonal to each other.

(3) Evaluation of TN mode liquid crystal display device Using the luminance meter (TOPCON BM-5), the front black state luminance and the white state luminance are measured and the front contrast is calculated for the manufactured liquid crystal display device. did. The front contrast was evaluated according to the following criteria.
A: 1200 or more and less than 2000 ○: 800 or more and less than 1200 Δ: 400 or more and less than 800 ×: less than 400 The results are shown in the following table.

In addition, viewing angle characteristics in the vertical and horizontal directions were evaluated. Specifically, the vertical / horizontal viewing angle contrast during black display was measured using a measuring instrument (Ez-contrast 160D, manufactured by ELDIM) and evaluated according to the following criteria.
◎ ... Sum of upper and lower polar angles where CR> 10 is 350 or more ○ ... Sum of upper, lower, left and right polar angles where CR> 10 is 250 or more and less than 350 Δ ・ ・ ・ Upper and lower where CR> 10 The sum of the left and right polar angles is 150 or more and less than 250 ×... CR> 10.

From the results shown in the above table, Examples 1 to 24 using the onium compound represented by the predetermined formula (I) are all excellent in adhesion between the optically anisotropic layer and the alignment film. Can understand.
In particular, in Examples 1 to 10 and Examples 13 to 21 using a 3-substituted benzene type discotic liquid crystal compound as the liquid crystal compound, the hybrid is in the reverse hybrid orientation and the slow axis is expressed in a direction orthogonal to the rubbing direction. It can be understood that an optically anisotropic layer was obtained.
On the other hand, Comparative Examples 1 to 5 using an onium compound (CI-1 to CI-5) outside the range of the formula (I), which has no polymerizable group or only at one end, In Comparative Examples 8 to 9, it can be understood that the adhesion between the optically anisotropic layer and the alignment film is significantly inferior to that of the example.
In Comparative Examples 6 and 7 in which no onium compound was added, considering that the adhesion was as high as in the examples, when the onium compound was added, the onium compound was unevenly distributed in the vicinity of the interface of the alignment film. It can be presumed that this is a cause of lowering the adhesion between the optically anisotropic layer and the alignment film. On the other hand, in order to utilize the alignment control ability of the onium compound, it is necessary to make it unevenly distributed in the vicinity of the alignment film. In the conventional technology using an onium compound as an alignment film side interface control agent, a stable reverse hybrid alignment state and high adhesion between the optically anisotropic layer and the alignment film are achieved at the same time. Was difficult.
According to the examples of the present invention, both stable formation of the reverse hybrid alignment state and high adhesion between the optically anisotropic layer and the alignment film, which are difficult in the comparative example using the conventional onium compound, are achieved. Achieved at the same time.

Further, from the results shown in the above table, in Examples 1 to 10 and Examples 13 to 21, an optical film having an optically anisotropic layer formed by fixing the reverse hybrid alignment state is used for optical compensation of a liquid crystal display device. Therefore, it can be understood that the viewing angle is compensated almost without being affected by the decrease in the front CR by the optical film.
In addition, since Example 11 and Examples 22-24 were not able to achieve a reverse hybrid orientation state, they were not suitable as a viewing angle compensation film of a TN mode liquid crystal display device.
Further, Comparative Example 7 is used for optical compensation of a liquid crystal display device having an optically anisotropic layer formed by fixing a positive hybrid alignment state horizontally aligned on the alignment film interface side and aligned at a high tilt angle on the air interface side. Therefore, the front CR was lower than that in the reverse hybrid alignment example.

Reference example:
An optically anisotropic layer was formed in the same manner as in Example 8 except that a polyimide film was used as the alignment film to obtain an optical film. However, the alignment of the liquid crystal molecules is disturbed, and a desired alignment state cannot be obtained, and the adhesion between the optically anisotropic layer and the alignment film is poor. From this result, it can be understood that it is preferable to use an alignment film mainly composed of modified polyvinyl alcohol, particularly modified polyvinyl alcohol having a repeating unit having a polymerizable group.

DESCRIPTION OF SYMBOLS 1 Support body 2 Alignment film 3 Optically anisotropic layer

Claims (15)

An optical film having a support, a rubbing-treated alignment film, and an optically anisotropic layer containing a liquid crystal compound in this order,
The optically anisotropic layer contains at least one onium compound represented by the following general formula (I):

In general formula (I), ring A represents a quaternary ammonium ion of a nitrogen-containing heterocycle; X represents an anion; L ¹ represents a divalent linking group; L ² represents a single bond or a divalent linking group. represents a group; Y ¹ represents a divalent linking group having a 5- or 6-membered ring as a partial structure; Z represents a divalent linking group having an alkylene group of C ₂ ~ ₂₀ as a partial structure; P ¹ and P ² independently represents a monovalent substituent having a polymerizable ethylenically unsaturated group. The optical film according to claim 1, wherein the at least one onium compound represented by the general formula (I) is a compound represented by the following general formula (I-1) or (I-2):

The definition of each symbol of general formula (I-1) and (I-2) is synonymous with each in general formula (I); L < ³ > and L < ⁴ > represent a bivalent coupling group each independently; Y ² and Y ³ are each independently a 6-membered ring optionally having a substituent; m represents 1 or 2, and when m is 2, two L ⁴ and two Y ³ are They may be the same or different; p represents an integer of 1 to 10. The optical system according to claim 2, wherein the at least one onium compound represented by the general formula (I) is at least one of the compounds represented by the following general formula (I-3) or (I-4). the film:

The definitions of the symbols in the general formulas (I-3) and (I-4) are as defined in the general formulas (I-1) and (I-2); R ′ represents a substituent; b represents an integer of 1 to 4; The optical film according to claim 1, wherein the alignment film is a film containing a modified or unmodified polyvinyl alcohol as a main component. The optical film according to claim 1, wherein the optically anisotropic layer further contains a copolymer containing a repeating unit having at least one fluoroaliphatic group. The optical film according to claim 1, wherein the alignment film side tilt angle of the molecules of the liquid crystal compound is fixed in an alignment state larger than the air interface side tilt angle. The optical film according to claim 1, wherein a slow axis direction of the optically anisotropic layer is orthogonal to a rubbing direction of the alignment film. The optical film according to claim 1, wherein the liquid crystal compound is a discotic liquid crystal compound. The optical film according to claim 8, wherein the discotic liquid crystal compound is a discotic liquid crystal compound having the following formula (X) as a discotic core:

In formula (X), each R represents an organic substituent necessary for the compound of formula (X) to exhibit liquid crystallinity. The optical film of any one of Claims 1-9 whose addition amount of the said onium compound is 0.5-3 mass parts with respect to 100 mass parts of said liquid crystal compounds. The addition amount of the copolymer containing the repeating unit having the fluoroaliphatic group is 0.2 to 2.0 parts by mass with respect to 100 parts by mass of the liquid crystal compound. The optical film as described. The polarizing plate which has a polarizing film and the optical film of any one of Claims 1-11 at least. A liquid crystal display device having at least the polarizing plate according to claim 12. The liquid crystal display device according to claim 13, which is in a TN mode. A vertical alignment agent comprising an onium compound represented by the following general formula (I):

In general formula (I), ring A represents a quaternary ammonium ion of a nitrogen-containing heterocycle; X represents an anion; L ¹ represents a divalent linking group; L ² represents a single bond or a divalent linking group. represents a group; Y ¹ represents a divalent linking group having a 5- or 6-membered ring as a partial structure; Z represents a divalent linking group having an alkylene group of C ₂ ~ ₂₀ as a partial structure; P ¹ and P ² independently represents a monovalent substituent having a polymerizable ethylenically unsaturated group.

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